Science Inquiry Final

Planck's constant

A fundamental constant, h, that relates the energy of light quanta to their frequency: h = 6.6 X 10^-34 joule·second

Week 5 Part 27: Einstein light quanta hypothesis (What did Einstein Asked?)

Asked: If light can appear to be composed of lumps, or quanta, in emission, couldn't the same thing happen in the absorption of light? Could the energy of the light be concentrated in lumps, and then be proportional to the frequency?

What are human beings made of?

Atoms

Week 2 Part 6: What is an Isotope?

Beryllium-7: 4 protons 3 neutrons trace Beryllium-9: 4 protons 5 neutrons almost 100% Beryllium-10: 4 protons 6 neutrons trace They all have the same chemical and physical properties, they are all isotopes.

Week 2 Part 1: What was the first question Luis Alvarez asked when his son Walt presented him with a rock preserved in transparent plastic that he found in the wall of a gorge at Gubbio in the Apennines of Italy

He asked why the clay layer had formed and how long had its formation taken?

Triangle P and X

Triangle P (delta P) The corresponding uncertainty in the other quantity we need to know when we are trying to pin down a particle, namely, its momentum, p, also along the x-axis. Triangle X (delta X) A symbolic way of representing the best we can possibly do, the closest we can come, or the residual uncertainty, in measuring the position of an electron along the x-axis of coordinates

Superposition of States (double slit experiment)

Two objects being at both places at the same time

Week 4 Part 24: constructive wave interference

the variation of wave amplitude that occurs when waves of the same or different frequency come together and the wave is increased

Week 2 Part 14: Scientific Inquiry according to Richard Feynman

-If it disagrees with experiment, it's WRONG. -In that simple statement is the key to science. -It doesn't make any difference how beautiful your guess is, it doesn't matter how smart you are who made the guess, or what his name is... If it disagrees with experiment, it's wrong. That's all there is to it."

Week 8 Part 11: What is the correct explanation of physical particles using Schrödinger's wavefunctions?

-Most accurate explanation: There is no electron, but only Schrodinger wave function of a electron. The wave function goes through both slits. We call that the different parts of the wave function are in superposition. No electrons, just wavefunction.

Gravitational fields

the region of space surrounding a body in which another body experiences a force of gravitational attraction.

Week 5 Part 24: Gravitational fields

the region of space surrounding a body in which another body experiences a force of gravitational attraction.

White objects

-Reflects all colors -Composed of equal amounts of the different colors of light -We can take the colors of light and combine them to make white light

Week 5 Part 7: electric field

the space around a charged object in which another charged object experiences an electric force

Schrodinger's Wavefunction

-Solution to Schrodinger's equation, done purely by mathematics, created a very unique way of solving these problems .-His angle of looking at things: everything is and is modeled by a wave, and describes electrons, photons, etc-in mathematical terms-as a wave

Week 2 Part 19: How did Luis Alvarez come up with his idea of the Impact Theory of Mass Extinction? Part 1

-"I invented a new scheme every week for six weeks and shot them down one by one." -Alvarez starting looking into incoming asteroids and comets and considered such an object passing through the atmosphere but missing Earth's surface -Because of this, he believed the object would then fragment into dust that would be captured by the Earth's gravity and fall into its surfacer

electric field

the space around a charged object in which another charged object experiences an electric force

Week 4 Part 17: Quantitative understanding of speed of light

-186,000 miles per second (299,792,458 meters per second) -Thunder and lightning, which one comes first and why? -1 second delay is about 370 yards away -The Sun is 91,663,000 miles from the Earth, how long does it take light to reach us? 493 seconds or 8'13" -How far is one light year? -Seconds in a year = 365x24x60x60=31,536,000 -Distance = 31,536,000 x 186,000=5,865,696,000,000 miles

Week 5 Part 23: magnetic fields

the space around a magnet where the force of a magnet can act, created by magnets for electrical currents

A Quantum Paddle - Where is the Dividing Line?

-2010: Andrew Cleland of UCSB (Santa Barbara) observed the FIRST visible object to be put into a superposition of quantum states. An object with a trillion atoms, or a billion times larger than the previous record. -Quantum Paddle: Size of a hair, but VISIBLE TO THE NAKED EYES.

Flipping a coin three times: possible outcomes

-8 possible outcomes: HHH, HHT, HTH, HHT, HTT, THT, TTH, TTT -Possibility of obtaining 3 heads: 1/8 -Possibility of obtaining 2 heads: 3/8 -Possibility of obtaining 1 head: 3/8 -Possibility of obtaining 0 heads: 0/8

Week 5 Part 30: Einstein wrote in 1905:

"... energy in a beam of light ... consists of a finite number of energy quanta, localized at points of space which move without subdividing and which are absorbed and emitted only as units." -In December 1926, American physical chemist Gilbert Lewis coined the name "photon" for Einstein's light quanta in a letter to Nature. -Energy is not smoothed out over all electrons, but concentrate on single electrons. -A fleet of boats is tethered off shore with firmly set anchors in a sea breeze. -Quantum picture:NO boats are waving, except one boat gets lifted by the wind. (all energy is concentrated in a single boat in dimmest light) -This agrees Hertz's experimental evidence, but difficult to understand by common sense

Bohr's response when people pointed out his arbitrary assumptions in his Atomic Model

"If you don't like it, get used to it, because they work, they don't ask why because if you assume that's the cate, you agree 100% with the experiments.

Week 8 Part 6: When Bohr says "get used to it", how do you understand it in the context of scientific method?

"If you don't like it, get used to it, because they work, they don't ask why because if you assume that's the cate, you agree 100% with the experiments. -Communication

Name of Heisenberg's fundamental paper

"On A Quantum Theoretical Reinterpretation of Kinematic and Mechanical Relations"

E=mc^2

-Bohr agreed that the loss of mass has an impact on the gravitational field -According to Einstein's Theory Of General Relativity, gravitational redshift affects the speed of the clock, yielding uncertainty triangle t in time measurement, which is required for the pointer to return to its original position.

Ole Romer

-A Danish astronomer who in 1676 made the first quantitative measurements of the speed of light., 300,000,000 meters per second (186,000 miles) -Originally used his telescope to measure the motion of the moons of Jupiter, where he discovered there was often a lag in the time that the moons disappeared and reappeared from behind Jupiter at the beginning and end of an eclipse. -The time lag was dependent on Jupiter's distance to Earth that changed over the course of a year on Earth -Romer realized he was observing an effect due to the finite speed of light

What is the smallest thing a microscope can observe in our natural light and why?

-A cell -But we cannot even observe things smaller than a cell, especially things inside the cell, even the nucleus -Why is that the case? This answer can be determined by physics -The answer is that it has something too do with the light's wavelength -If you want to see the details inside the cell, you need a good resolution and you need to use a shorter wavelength (ex: purple) -Poor resolution would be a red light, which is blurry because your lights wavelength is longer

Week 4 Part 22: Double-slit experiment

-A demonstration that light and matter can display characteristics of both classically defined waves and particles. -Thomas Young's most famous was the double slit experiment-a demonstration that light and matter can display characteristics of both classically defined waves and particles and the first of many experiments illustrating the wave property of interference

Hydrogen Spectrum

-A glowing solid gives out visible light for all frequencies, a gas at a low pressure gives out sharp spectral lines, which represent certain well-defined frequencies because on a solid, the atoms are so close together that they interfere with one another so that they cannot express themselves by the radiations characteristic of their undisturbed mode of behavior -Gasses in the discharge tube cause atoms to separate widely. -Johann Balmer (1825 - 1898) was a Swiss mathematician and mathematical physicist, he discovered an empirical formula in 1885, later called the Rydberg formula. RHis measured in experiments. -He could not explain why -Simplest type of spectrum -Look at pictures on phone

Week 8 Part 14: What's Heisenberg's major contribution to quantum physics? (Uncertainty principle) Part 2

-A result from Heisenberg's "Matrix Algebra", which he used to explain/calculate all the spectral lines -Many people may refer things as an uncertainty principle to explain them -The more accurately you measure an object's position, the more uncertain you will be about its speed and vice versa, no matter how good your equipment may be. -And this is not due to issues with measuring equipment. Its part of nature. -Your error measuring the position and speed has to be greater than some constant -We cannot tell the difference between speed and position in real time but according to quantum physics, there is a difference even if you can't see it -With this principle, Heisenberg was able to give a very good explanation of Niels Bohr's hypothesis: the electrons running around the nucleus will have the smallest orbit, that they cannot go further in the nucleus, which had puzzled many beforehand -Look at numbers in the slide of the same name on your phone, 4/1/20

Week 9 Part 5 What are the key concepts of the Copenhagen Interpretation? (also refer to week 10 learning) Part 1

-A year after Schrodinger's equation, Niels Bohr (the leader of this interpretation) recognized that there was something very important coming out of Heisenberg's and Schrodinger's equations. -This made him realized that physics had encountered the observer and that the issue had to be addressed.-The other major contributor to this interpretation was Bohr's young colleague, Heisenberg -Strongly supported by Max Born, Wolfgang Pauli, Bohr and Heisenberg. -Adopts the simple view that only the observed properties of microscopic objects exist. There is no objective reality.

Week 4 Part 21: Thomas Young Part 3

-About a decade later, a French physicist, Augustin Fresnel confirmed and extended Young's results, leading to the idea of light as waves to be established. -The idea of light as waves was established which led to the design of many refined optical instruments, from microscopes to telescopes, based on light waves.

Week 8 Part 13: What's the main idea of Experiment 7 (longer waves)

-According to Einstein's Photoelectric Effect, a softer kick means lower frequency photon, or redder color (longer wavelength) -If we can use "gentler" light perhaps we can avoid disturbing the electrons so much and to reduce the intensity/number of kicks by moving to a longer wavelength (red color). -By doing this, we don't disturb the fragile electrons -So we keep repeating the same experiment while changing the color of light from white to red

Week 6 Part 16: An Immediate Problem

-According to Maxwell's theory, an electron moving around the nucleus would: ->radiate electromagnetic energy -> lose energy -> the circular orbit would diminish -> a corresponding increase of frequency. -Just as a satellite spirals to a crash on earth as it loses energy to the drag of atmospheric friction. Planetary atoms could exist for about one millionth of a second. -But we know Balmer series is not continuous and all of us and the atoms in our body are fine. -This was a fatal flaw for Rutherford's model. Thomson plum pudding hypothesis -> Rutherford gold foil -> mini-solar system hypothesis -> conflict with Maxwell theory -> another hypothesis?

Week 10 Part 8: What's Copenhagen Interpretation's view on reality?

-Adopts the simple view that only the observed properties of microscopic objects exist. There is no objective reality.

Einstein's Second Challenge To The Uncertainty Principle Part 3: Bohr Triumphs

-After a sleepless night, Bohr finally figured out the flaw in Einstein's second challenge. -The flaw was that Einstein violated his own general theory of relativity. -Years later, Bohr revisited this triumph with a nuts-and bolts caricature of Einstein's Photon In A Box experiment illustrating his general rule preventing such refutation: -In any quantum experiment, one must consider the macroscopic apparatus actually used. -Bohr's arguments convinced Einstein that the theory was at least consistent and that its predictions would always be correct. -A humbled Einstein went home from the conference to concentrate on general relativity, his theory of gravity

Week 5 Part 32: 1905, The Year in Science

-Albert Einstein (1879 - 1955) No previous year rivals it, none has matched it since. -In 1905: The theory of relativity was put forth practically full blown The photon hypothesis was proposed The atomic nature of matter was firmly established. -It was all done by the same man in his spare time as he earned his living as "Technical Expert, Third Class" in the Swiss patent office.

Week 11 Part 10: Understand how the experiments are set up to test Bell's Theorem (see first slide, 4/29/20)

-Alice & Bob each have a special "detector", a three-stage wheel with a polarizer to measure the orientation of the photon -The wheel can only randomly stop at A (0 degrees), B (120 degrees), and C (240 degrees) with equal probability (1/2) -Two lights on the wheel (red and green) -Measurement can only take place in that blue circle/window -Alice and Bob each spin the wheel separately until the wheel stops, the light source then fires a pair of photons. Alice & Bob then measure the orientation's photon (top position) through the wheel's window. -Can only stop at 1 of 3 positions. 120 degrees between each pair of all 3 positions.

Week 11 Part 13: Understand how the instruction sets work

-Alice and Bob are required to have the same instruction set because this is how the photon pair is produced. -The photons will carry the instructions (how we set color, ex: if a photons lands on A, what color should we see) to both detectors -An instruction set for both detectors might read: If the detector is set to A then it flashes red, if set to B then flash red, if set to C then flash green: -ABC arrow RRG (A is R, B is R, C is G) -What colors will the detectors flash? It depends on the orientation settings of the two detectors. We will use our knowledge of probability to figure it out: -Ex: Suppose Alice's detector is set to C, and Bob's detector is set to A, then Alice will see a red light and Bob a green light, therefore for this scenario. we label it as: -CA arrow (GR) (Alice Bob orientations) arrow (Alice Bob colors) -List all possible outcomes. There are 9 possible outcomes in this experiment. What is the probability Alice and Bob will see the same color? 5/9 times.

Week 5 Part 12: Ultraviolet catastrophe (look also at the other definition)

-All material emits light. -Most objects radiate the same way when heated. -Maxwell's electromagnetic radiation predicts that intensity is proportional to number of waves in a unit square. -Same square can pack more blue waves than red waves, thus more energy in the blue. -Infinite amount of energy at shorter waves, violation of conservation of energy, the "Ultraviolet Catastrophe"

Week 6 Part 11: Experiment 3, the conundrum of electrons Part 1 (Set-up)

-All the electrons will have (nearly) the same energy, similar to photons with same color (frequency) [at production] -We hear sharp "clicks" from the detector (that is, from the loudspeaker). And all "clicks" are the same. There are no "half-clicks." -So whatever arrives at the backstop arrives in "lumps." [at detection] -All the "lumps" are the same size: only whole "lumps" arrive, and they arrive one at a time at the backstop. -We shall say: "Electrons always arrive in identical lumps." (discrete) -We count number of clicks as we did in the bullet experiment.

Week 2 Part 20: How did Luis Alvarez come up with his idea of the Impact Theory Of Mass Extinction? Part 2

-Alvarez first used the comet that fragmented over Tunguska, Siberia in 1908, which destroyed many square miles of forest. -He realized he could show the deceleration of a 10 kilometer diameter asteroid or comet passing through the atmosphere was the same as the acceleration of gravity on the Earth. Not enough force (rain drops) -Alvarez then used his father's 1888 volume on the Krakatoa volcano. -Using George Storkes' measurements of Krakatoa dust particles: "I concluded that a ten-kilometer piece of solar system debris hit the earth sixty-five million years ago and threw dust into the stratosphere that made the sky dark as midnight for several years"

Week 2 Part 16: Chris McKee

-Alvarez's astronomy consultant who suggested that the iridium could have been deposited by a ten-kilometer asteroid hitting the Earth. -Credit where credit is due in science: "Our Science paper didn't carry the acknowledgment we originally wrote of Chris's contribution, because a referee said the idea was obvious."

Week 5 Part 17: What is thought experiment

-An analysis of a well-defined hypothetical question where reasoning is applied through what-if scenarios. -Originated from German Gedanken-Experiment. -Physicists such as Einstein, Schrodinger used thought experiments extensively. -It may not be possible to conduct thought experiments in labs. -Can thought experiments be used to support a hypothesis in scientific inquiry?

Week 9 Part 6,: What are the key concepts of the Copenhagen Interpretation? (also refer to week 10 learning) Part 2

-An atom's wavefunction and the atom itself are the same thing. -So when you talk about the atom, you are really talking about the wavefunction. The only way to explain everything consistently -"No microscopic property is a property until it is an observed property". John Wheeler, Cosmologist. -Classical physics is modified, only a special case of quantum physics -For all practical purposes, big things allow a classical description. And, according to Copenhagen, that all we need to concern ourselves with.

Blackbody

-An idealized object that absorbs all the light incident on them (all colors or all frequencies). -It does not reflect light

de Brogile Part 4: Experimental Confirmation: An Accident

-At AT&T's research, scientists Clinton Davidsson and Lester Germer from New Jersey in Bells Lab observed the first interference of electron waves -But they did this to study the surface of the nickel initially, not to confirm de Brogile's hypothesis, which they had no prior knowledge of. -They were studying the properties of vacuum tubes by shooting springs of electrons at various metal surfaces. -In 1927, in an effort to clean the surface of a metal by heating it, Davidsson accidentally crystalized it. Electrons bounced off the clean metal surface showed interference patterns, which fit de Brogile's results beautifully: Electrons are just like light waves. -These crucial "electron diffraction" experiments verified the de Brogile connection between momentum and wavelength, and was the first experimental confirmation of the wavelength of electrons

Week 9 Part 7: What are the key concepts of the Copenhagen Interpretation? (also refer to week 10 learning) Part 3

-Atomic-scale objects do not exist on the physical world. If so, it's okay that they don't make sense-It promotes the collapse of the wave function upon measurement. -It is generally based on the following: 1) The uncertainty principle 2) The complementary principle 3) The statistical interpretation of Born, based on probability determined by the wave function. -Now we can calculate everything, but the problem on the philosophical level was that objective reality was called into question

Week 2 Part 15: The Scientific Process

-Basic elements: Observation, Hypothesis, Experimentation, Communication -However, each step can interact with any other step, not necessarily in the same order. -Any theory is not final, but the process is the same.

Week 2 Part 21: Challenges of Alvarez's Discovery (Weak)

-Bill Clemens, a Berkeley paleontology professor, insisted that the dinosaurs went extinct 20,000 years before the asteroid impact. (Frank and Helen found the iridium layer three meters or 20,000 years, above the most recent dinosaur bone) -No convincing reasoning backs up the idea, it seems like one outlier sampling error. (cherry picking and statistics) -Bill agreed to disagree. Bill finally accepted the impact theory but denied its connection with the sudden dinosaur extinction, for which he offers no competing explanation. (I once said, "Bill's theory is that our theory is wrong.")

Week 6 Part 12: Experiment 3, the conundrum of electrons Part 2 (Actual Experiment)

-Blocking one opening (2) decreases the number in some cases (maxima). -Blocking one opening (1)increases the number in some cases (minima). -How do we reconcile both? -We know it was a "lump" at production, as well as detection, but we seem to have lost all that information in between... -The electrons arrive in lumps, like particles, and the probability of arrival of these lumps is distributed like the distribution of intensity of a wave. -Electron behaves "sometimes like a particle and sometimes like a wave."

Week 8 Part 7: What is Bohr's Principle of Correspondence? Part 1

-Bohr and Heisenberg adopted this principle during their stay in Copenhagen -It would later be part of the Copenhagen Interpretation, and the first part of the interpretation developed -Quantum laws should be so constructed as to blend seamlessly with classical laws when the systems described get large enough. -In other words, when quantum laws are applied to an everyday object in the microscopic world, they should agree with Newton's laws (classical physics) when we move from electrons to cars and baseballs. (No conflict between the two)

Einstein's Second Challenge To The Uncertainty Principle Part 2: Bohr is Shocked, According to Leon Rosenfeld's journal

-Bohr was shocked -This challenge put Bohr through a sleepless night -At first, Bohr could not even think of a solution to Einstein's challenge. -He tried to persuade other scientists that Einstein's challenge could not be true -If Einstein was right, Bohr believed, it would be the end of physics

Week 9 Part 1: The Copenhagen Interpretation What's the Born Rule? What's the significance to science?

-Born's most famous contribution -Was formulated by Max Born in a 1926 paper, a key quantum mechanical principle -First person to explain how we CAN BETTER UNDERSTAND QUANTUM MECHANICS -He was also able to explain the meaning of the wavefunction -A few months after Schrodinger announced his equation, Max Born realized the idea of "matter waves" that approximate the shape of a particle doesn't work as an interpretation of Schrodinger'ss wavefnction -Born realized that the waviness in a region was probability, providing a new physical interpretation of the wavefunction, which was strongly influenced by Heisenberg's Uncertainty Principle

Schrodinger and Heisenberg's experiments today

-Both are used today -This more mathematically tractable Schrodinger version is generally used today to picture, while Heisenberg's is used to try to calculate, especially larger systems. -Heisenberg's is easier for computers to handle large amounts of data

Week 2 Part 18: Challenges of Alvarez's Discovery (Additional Evidence)

-Boundary clay iridium could have been precipitated by a sudden change in ocean chemistry rather than brought in by an asteroid. We countered with a prediction that iridium would be found in rocks formed on continental sites, far from any ocean. -We prepared a proposal for a federal grant to examine a Montana site. The proposal was rejected because a peer reviewer reported, in effect, that we'd be wasting money looking at a continental site since everyone knew the iridium was precipitated out of the ocean chemically. -The Los Alamos group found iridium at New Mexico's Raton Basin. The K/T iridium didn't come from the ocean. It was deposited on the continents as well as on the ocean floor. The Los Alamos discovery added great strength to our theory.

Week 5 Part 5: What causes a bright or a dark fringe

-Bright fringe: When the difference of distances from each slit to P corresponds to one cycle or wavelength -Dark fringe: When the difference of distances from each slit to P corresponds to one half cycle or half wavelength

Week 4 Part 14: Classical physicist's worldview

-By the end of the 19th century, Newton's classical mechanics and Maxwell's electromagnetism gave scientists a powerful set of intellectual tools to explain the universe in classical terms. The worldview is what we call today "classical physics":(1) Determinism (2) Physical reality

Week 2 Part 7: What is half-life?

-C-14-5,700 years -Beryllium-10-1,390,000 years -Iridium-77-75,000,000 years It's all about counting "by half"

Week 9 Part 18: Malus's law (cosine) itself is not required but the conclusion is important (probability is ¼ at 120 and 240 degrees), what he says "Number of photons/energy passing polarizer 2 is close square 2 (0 with line in the middle)" and how it is used to calculate overall probability of light passing two polarizers.

-Calculate Cosine 90, which is 0, which is why you get no light coming out of the second polarizer when you rotate it -Polarizer 2: These different angles, you can use the law to calculate the probability. We are particular interested in the 120 degree angle (Polarizer 2, Probability 1/4) -Cosine 120, the square of that is 1/4-25% of light can come through the second polarizer if it is 120 degrees away from the first one here. -If the second polarizer is the same 0 degrees, all the light will come through, cosine 0 is 1, meaning 100% it will come through3rd one: Polarizer 2: 240 degrees -Calculate cosine 240 and the square of that is the same, 1/4 -This is how we use Mulas' Law to calculate the probability of a photon going through the second polarizer, depending on the angle

Week 2 Part 22: Challenges Of Alvarez's Discovery (Flawed)

-Charles Officer and Charles Drake of Dartmouth College. -They published two articles in Science claiming that volcanic activity explained the experimental evidence better than an impact. (a flawed paper gets published, as well as real scientific breakthroughs get rejected, but that's ok). -They stated that they found sanidine spherules almost everywhere above and beyond the clay layer, in sharp disagreements with our team's observations-Walt countered that they hadn't cleaned their samples of surface contaminants, leading the other scientists to burst into laughter

Week 11 Part 5: Understand the similarities and differences among the classical, semi-classical and quantum Alice and Bob thought experiments: Classic

-Classical analogy: We know Alice and Bob's cars (which are pushed apart by a strong spring and go at the same speed in opposite directions) are physical reality, and which way they are going. Alice, who gets her car first cause its closer, instantly knows the position of Bob's car. EPR claims the position of Bob's car is a physical reality, meaning it was created without Bob seeing it.

Week 8 Part 9: Where does Schrödinger's reaction to Heisenberg's matrix mechanics fall in the context of scientific method (which step)?

-Communication

Addition of Waves with Different Wavelengths (How can we use waves to describe a particle?)

-Constructive (add 2 together=1 big wave) and destructive interference (add 2 together=complete cancellation) in Thomas Young's double slit experiment were explained using the exact same waves, with identical wavelength. -But what if this time, we use different wavelengths? What would we see? -1 red wave (full wavelength) +2 green waves (same space)=blue wave (bit higher on the center, lower on the side) -1 red wave+2 green waves+3 purple waves=blue wave (Peak is slightly higher than the blue wave in the first equation)

The Copenhagen Interpretation: Complementarily

-Copenhagen invokes the "complementary" principle to confront a spooky aspect of observation: the instantaneous collapse of an object's wavefunction everywhere by an observation anywhere. -Central idea of complementarity is a WORLD THAT IS SOMEWHAT DIFFICULT TO UNDERSTAND, the CORE of the Copenhagen Interpretation -The two aspects of a microscopic object, its particle aspect and its wave aspect, are "complementary", and a complete description requires both contradictory aspects to describe nature in a consistent way, but we must consider only one aspect at a time. -We have never been able to observed a wave and a particle at the same time. -Physicists and scientists still working on it to this day.

Week 4 Part 15: What are some of light's interesting behaviors?, basic ideas of diffraction, refraction, reflection and polarization

-Danish physicist Erasmus Bartholinus (1625-1698) discovered polarization of light in 1669. -Light coming from a lamp or the Sun has all kinds of polarizations, Light through a polarizer has only one polarization. -Light through a pair of polarizers at 0o, 90oor between (45o).

de Brogile Part 5: Just Another Double Slit Experiment

-Davidsson had just accidentally built the right double slit to see the interference of electron waves. At certain angles, there would be constructive interference. -de Brogile: Won the Nobel Prize in 1929 -Davidson and Germer: Won the Nobel Prize in 1937

Week 1 Part 4: What is Quantum?

-Describe how "little things" behave -Complicated math-The outcome of an experiment cannot, in general, be predicted exactly-2⁄3 of US economy depends on quantum theory, trillions of dollarsCell phone, LED light, TV, computer, MRI, Laser, X-Ray, CD/DVD, MicrowaveAll of chemistry and biology Superconductivity, Cryptology, Superfluidity...

Schrodinger's Reaction To Probability

-Did not accept that after the old Newtonian world of absolute certainties, Mother Nature does roll dice at a more fundamental level.-But according to quantum physics, you have to give up Newtonian classical physics cause it doesn't work that way.-Made his comments in the first few Solvay conferences

Week 8 Part 2: What's the main idea of Experiment 6 (dimmer light)?

-Einstein says that we need to turn the brightness down, so that the light waves will be weaker and not disturb the electrons as much. -There would be fewer photons flying around, decreasing the chance that these photons will hit the electrons. -Reduce the number of kicks -The flashes of light scattered from the electrons as they pass by do not get weaker (same strength). It is always the same-sized flash. -Dimmer light means fewer photons but with the same energy (Einstein's photoelectric effect) -Electrons go one at a time

Week 4 Part 9: Michael Faraday

-Electromagnetic induction -Asked in reverse if a magnetic field can produce an electrical field and it does when it varies in time. -Faraday discovered this by running a large electoral current through a tightly wound coil to create a strong magnetic field. He then used a charged wire as a probe when he tested for an electric field, it wasn't seen. -So he reduced his magnetic field to zero -It was seen briefly before stepping back into 0, which revealed the presence of an electric field -Experimental physicist, Law of Induction

Week 7: Part 1: Everything is a Wave! Matter wave hypothesis and its first experimental confirmation, modern evidence of matter wave

-Electromagnetic radiation was somehow both an extended wave and an extended stream of compact particles -Around this time, de Brogile tried to figure out what a photon is -Sometimes light is a wave, and other times, it is a particle -If light waves seemed to have particle properties, maybe the reverse is true?-MAYBE ALL PARTICLES DEMONSTRATE WAVE PROPERTIES -The concept of photons was well received. -Matter was made of particles. It was a collection of atoms, little objects whose size was well known (Rutherford). -And atoms were made of tiny hard nuclei surrounded by electrons (compact little objects) -But were other things such as atoms and electrons, etc? Could these particles be waves? We know photons are particles.

Week 2 Part 27: The Scientific Process: Unanswered Questions (Alvarez)

-Eugene Shoemaker, an expert on earth-crossing asteroids and moon craters, calculated that a ten-kilometer asteroid should hit the earth once every 100 million years. -There have been five major extinctions since the Cambrian period began, about 500 million years ago. -High level of iridium has not been found in all five boundaries, partly due to limits of equipment sensitivity, mishandling of rock samples etc.

Week 5 Part 31: Was Einstein's photon hypotheses accepted when he won the Nobel Prize for it in 1921?

-Even when Einstein was awarded the Nobel Prize in 1921, the citation discreetly avoided explicit mention of the then seventeen-year old, but still unaccepted, photon hypothesis. -An Einstein biographer writes: "From 1905 to 1923, [Einstein] was a man apart in being the only one, or almost the only one, to take the light-quantum seriously".-Einstein never won the Nobel prize for his theories of relativity.

Overall view On Quantum Theory About the World

-Experiment 1: Bullets, no interference -Experiment 2: Water waves, interference, wave behavior -Experiment 3: Electrons, one opening at a time, particle behavior, both openings, wave behavior -Experiment 4: Single electron, initially random and particle behavior, after a while, interference and wave behavior -Experiment 5: Watching electrons with a bright light, no interference, particle behavior -Experiment 6: Watching electrons with a dimmer light, some behaved like a particle (when seen), some behave like a wave (when unseen) -Experiment 7: Watching elections using a longer wavelength light, unable to tell which opening they go through and there is interference pattern, wave behavior.

Week 4 Part 2: What's the significance of Galileo's contribution to problem solving? #1

-Experiments to test a hypothesis -One of the first to try to pin down the velocity of light. -With two assistants, they counted out loud and tried to discern a delay as the distance to an observer was increased. It failed since the speed of light is too large to measure this way. -The speed of sound is 1,000 feet per seconds, so it will take 5 seconds for the thunder clap to travel 5,000 feet in a mile.

Week 11 Part 14: Understand how the probability is calculated for a given instruction set

-For a given instruction set which determines Alice's & Bob's color flashes for one of the nine possible orientations, five of them lead to the same color flashes. -Alice and Bob are required to have the same instructions because this is how the pair of photons are produced at the source. -There are eight possible outcomes 1. ABC arrow RRR 2. ABC arrow GGG 3. ABC arrow RRG 4. ABC arrow RGR 5. ABC arrow GRR 6. ABC arrow RGG 7. ABC arrow GRG 8. ABC arrow GGR

Week 4 Part 26: Interference Of Waves

-For these two crests to arrive at the same time, the waves from B must have travelled exactly one full wavelength more than those from A. -When the distance is exactly one-half wavelength farther from one opening than the other, crests from A arrive along with troughs from B. Interference of Waves -Waves from two sources add "constructively" to give a maximum of waviness--brightness, in the case of light, or add "destructively" to give a minimum of waviness-- darkness. While we talk of light waves, what we say holds for any wave.

Week 4 Part 11: James Clerk Maxwell (1831-1879) Part 1

-Formulated that electricity, magnetism and light are manifestations of the same phenomenon. -Found there was no symmetrical analogue of Faraday's law of induction -Theoretical physicist. -A changing (moving) electric field(E) can also produce a magnetic field(B), the waxing and waning of the electromagnetic waves would travel at speed of light (prediction)

Week 4 Part 12: James Clerk Maxwell (1831-1879) Part 2

-Found that his electromagnetic fields could escape from the proximity of wires and magnets that produced them and would then move through space with a speed equal to 186,000 miles per second. -Concluded that light is a electromagnetic disturbance, a tightly coupled mixture of pure oscillating electric and magnetic fields, propagating through space at a velocity of c=300,000 kilometers per second -A teacher-student relationship between Faraday and Maxwell

Week 2 Part 11: What were the results when the first hypothesis was tested again?

-Frank and Helen are careful scientists. Despite their certainty that they had detected the anticipated amount of Pu-244 in the boundary clay, they repeated their entire difficult and tedious procedure with a second sample of the same clay to confirm their results. -To their great consternation they found no Pu-244. -It turns before their first examination, a sample of manmade Pu-244 had been bombarded in the Radiation's Lab's linear accelerator, leading a Pu-244 particle to dislodge from their target and rest in their tiny beaker. -Alvarez immediately cancelled the talk

Frequency

-Fundamental characteristic of radiation -The rate at which crests or troughs pass a given point in space -Speed of light divided by its wavelength

Week 5 Part 22: Heinrich Hertz (1857-1894)

-German scientist who put to the test Maxwell's electromagnetic hypothesis of light.-Generated electric and magnetic waves and demonstrated that they obeyed the laws of reflection, refraction, diffraction, and interference

Week 8 Part 14: Surprise of Experiment 7 -Green...Yellow...Red...a terrible thing happens -We start to see a big fuzzy flash in the middle that we no longer can tell which opening the electron went through!

-Green...Yellow...Red...a terrible thing happens -We start to see a big fuzzy flash in the middle that we no longer can tell which opening the electron went through!

Plum Pudding Model

In 1905, Thomson had proposed a model of the atom in which the positive charge is dispersed evenly throughout a sphere covering the entire atom, with electrons embedded in it like plums in a pudding

Week 10 Part 9: What's Einstein's view on reality?

-He insisted that even little things have reality, whether or not anyone is looking. And if quantum theory said otherwise, it had to be wrong "God does not play dice"

The Born Rule/Waviness Of Probability: How did Schrodinger solved his equation

-He used the hydrogen atom. -However, at the time, no one really understood what the wavefunction meant because it had something unusual inside (square root of -1, which doesn't exist in nature). -That was when Max Born realized the waviness in a region was a probability

Week 2 Part 4:What was the first action taken by Luis Alvarez

-He wanted to see how long the clay layer took to form so Luis and Walt looked in the clay for traces of radioactive isotopes -But the suggestion later fell through when the half-life of the closest isotope, beryllium 10, was ten times two short (1.5 million years)

Week 11 Part 3: What are "hidden variables"? How does that support EPR's arguments?

-Hidden variables are unseen influences that affect the outcome of events. -In an EPR Experiment, what may seem to be instant could actually be driven by hidden variables that we don't know how to describe. -It supports EPR's arguments because according to their argument, if hidden variables are present, then quantum theory is incomplete -Very difficult to describe hidden variables, however, in physics, we know there is a way to do that.

Week 11 Part 9: What is "spooky action at a distance"?

-How Eisntein referred to the idea that any objects that have ever interacted continue to instantaneously influence each other. -Ex of this: Events at the edge of the galaxy influence what happens at the edge of your garden. -The two photons are "entangled" in a superposition state demonstrating a wave-like behavior until it's observed by Alice where wavefunctions collapse instantaneously.

Probability of Getting a Vertical Photon Part 2 (Actual experiment and conclusion): Look at slide with the same name 4/9/20

-How do we do this: We shoot 100 photons this way into the 2nd polarizer. 1st polarizer is not changing (not moving at all, always stays vertical). -When shooting 100 photons, we randomly set the 2nd polarizer to take one of the three positions. How many photons do we get in the end? -There is a probability of photons getting through each position. Let's look at the 3 different scenarios: -If Polarizer 1 is vertical and Polarizer 2 is at A, chance of getting a vertical photon is? 1 (100%) (100% chance it will go through) -If Polarizer 1 is vertical and Polarizer 2 is a B, chance of getting a vertical photon is? 1/4 (25%) -If Polarizer 1 is vertical and Polarizer 2 is at C, chance of getting a vertical photon is? 1/4 (25%) -The total probability will be the sum of all 3 scenarios: -A: (1/3 x 1) + B: (1/3 x 1/4) + C: (1/3 x 1/4) = 1/2 or 50%, meaning we get 50 photons in the end -Same applies if everything is horizontal -This is how we apply the probability calculation in quantum physics. -Chance of landing at position

Week 10 Part 2: Understand the conceptual significance of the probability of a person going through the wall is not zero.

-If a person was considered as a single object, like a gigantic "electron", moving at 1 (m/s), penetrating a wall of 2 (m) high and 0.1 (m) thick -Look at slide with similar title for equation, 4/20/20-it has 10 over 35 before you find an actual number -Suppose a million people try to walk through this wall a trillion times a second since the beginning of the universe 13.7 billion years ago, that is 1,000,000,000,000 (persons) x 1,000,000,000,000 (times) x 13, 700,000,000 (years) x 365 (days) x 24 (hours) x 60 (minutes) x 60 (seconds) = 4 x 10 over 41 times, multiplied by the above number, the probability is still zero, meaning it will take practically forever for it to happen -But, even if the probability is too small, it is not zero! There is no conflict between quantum objects and everyday objects!

Week 7 Part 2: Quantitative understanding of matter waves

-If light waves seemed to have particle properties, maybe the reverse is true? -MAYBE ALL PARTICLES DEMONSTRATE WAVE PROPERTIES -The concept of photons was well received. -Matter was made of particles. It was a collection of atoms, little objects whose size was well known (Rutherford). -And atoms were made of tiny hard nuclei surrounded by electrons (compact little objects) -But were other things such as atoms and electrons, etc? Could these particles be waves? We know photons are particles.

What is the simple way to tell the difference between correlation and causation.

-If we take out A, will B still happen? -Do a randomized trial, take out the cause and see if the effect still happens

Week 9 Part 19: Dangers of using statistics (biases)

-If you try to convince people of these numbers, you will be successful most of the time because people are not trained statistically, which is we found the quantum physics so hard to understand/to explain because our brain is not trained to understand statistics -Think of statistical numbers carefully, don't jump to conclusions. This is how we stay objective and independent -Ex: 31st had less speeding tickets than the 28th and 30th. This is wrong because there are only 7 months with 31 days so the person who did the survey only counted 7 months, not 12 months. This is how they hide information

Week 4 Part 6: Newton's corpuscular theory of light

-In 1672 Isaac Newton offered Corpuscles theory to explain other properties (deflection, refraction, traveling in a straight line etc). -Light is "a shower of tiny invisible particles" -Until a light beam contacts an object, which could exerted a "force", the light travels in a straight line. -It reflects at an angle equal to its incident angle like a bouncing ball. -Newton thus declared light to be a stream of "corpuscles", little bodies, or particles. -Light is a bunch of photons when they travel through space, they hit something and bounce back to our eyes. -Refraction (look at definition) -Newton says the glass or water medium "pulls" the particles to change direction, rainbow of colors-The particle picture triumphed. Many say that the weight and authority of Newton tipped the scales for more than 100 years.

Week 5 Part 16: Compton's experiment as a supporting evidence of the light quanta idea

-In 1923, Arthur Compton dramatically showed that light behaved like a stream of tiny billiard balls, photons. -Compton did not arrive at his radical explanation for the scattering process until all his previous attempts at an explanation had failed. -Arthur Compton was awarded the 1927 Nobel Prize and played a major role in the development of 20th century physics in the USA -Light is a particle. -What happens if we put light particles through a double slit?

Week 10 Part 4: Connect Schrödinger's cat with Experiment 4 (single electron double slit) in terms of superposition, collapse of wavefunction in explaining what happens in both cases

-In both cases, the wave function collapse when the objects are observed (the cat in Schrodinger and the dots in experiment 4)

Week 7 Part 8: Experiment 5, compared to experiment 4, what did we learn?

-In experiment 4, we learned that after we shoot particles one at a time for a while, they go from initially random and particle behaviors but after a while, we get an interference pattern and wave behavior -In experiment 5, we conclude that when we look at the electrons the distribution of them on the screen is different than when we do not look. Nothing is going through both openings, just like the bullets who go through 1 and 2. We know what the electron is doing between production and detection but we lost the interference pattern. BY LOOKING, WE ARE CHANGING NATURE

Week 4 Part 10: How do we know Maxwell's theory is correct?, what's his main contributions to science?

-In the field of electromagnetism, Maxwell formulated that electricity, magnetism and light are manifestations of the same phenomenon. -German experimental physicist Heinrich Hertz experimentally generated electric and magnetic waves and demonstrated that they obeyed the laws of reflection, refraction, diffraction, and interference. (confirmation)

Week 11 Part 17: Relate the single electron double slit experiment to the Alice and Bob experiment, what do they have in common? How Copenhagen Interpretation explains both on a consistent basis?

-In the single electron double slit experiment, where the electron is not being observed, its wavefunctions are spread-out in space in superposition. -Upon hitting the screen, it is being observed and the wavefunctions instantaneously collapse into a particle, even if the wavefunctions are in the entire universe, its collapse is instantaneous and takes no time, just like when Alice gets to know her photon, she knows Bob's photon at the same time. -So quantum theory is self-consistent

de Brogile Part 3: What is the ultimate test of a wave?

-Interference -But de Brogile's theory was still a hypothesis because it was not experimental -de Brogile connected the Newtonian momentum of an electron (mass times velocity) to the wavelength of the "electron wave" through Planck's formula. But electrons are particles? Where is the wave? -de Brogile looked around for some yet unexplained experimental observations that could be understood only in terms of his new hypothesis but found none. -No one had ever seen an interference phenomenon with electrons or any other material particle. -Look at requirement in your phone (Slide 6, 3/25/20) -The double slit would not work because of the size of a few atomic diameters. It is just impossible to ask a machinist to cut it. -There is no way we can find the right double slit to see the interference pattern

Week 4 Part 5: How do we know Newton's laws work?

-Isaac Newton (1643-1727) -Three laws of motion and law of gravity that predict how everyday objects move (and confirmed by baseballs, cars, rockets, planets etc.) -Same set of rules govern terrestrial as well as celestial bodies. -The universe can be explained by math. -Predicted that Neptune is the eighth and farthest known planet from the Sun in the Solar System. -It was mathematically predicted by Newton's Laws and was observed on the night of September 23-24, 1846,at the Berlin Observatory, by astronomer Johann Gottfried Gall

Week 8 Part 15: Surprise of Experiment 7 Explained

-It is impossible to arrange the light in such a way that one can tell which opening the electron went through, and at the same time not disturb the pattern. -According to Heisenberg, the new laws of nature governing quantum objects could only be consistent if such limitation exists. -If an apparatus is capable of determining which opening the electron goes through, it cannot be so delicate that it does not disturb the pattern in an essential way. -No one has ever found or even thought of a way around the uncertainty principle since the establishment of quantum physics 100 years ago, not even Einstein, who also failed to challenge the uncertainty principle. -So we must assume that it describes a basic characteristic of nature.

Week 1 Part 2: Why Scientific Inquiry?

-It is not about any subject in science, it is about how to think critically. -It is about how to find truth.

Week 6 Part 19: The Nucleus - The Rutherford Model

-J.J. Thomson's rice puddings hypothesis was wrong -Atoms have a heavy and positively charged core at the center, the nucleus, the electrons are orbiting the nucleus to maintain neutrality -Hypothesis -> Experimentation -> New hypothesis -The modified hypothesis: The mini-solar system.

Week 6 Part 20: J.J. Balmer and the Hydrogen Spectrum

-Johann Balmer (1825 - 1898) was a Swiss mathematician and mathematical physicist, he discovered an empirical formula in 1885, later called the Rydberg formula. RHis measured in experiments. -He could not explain why

Week 2 Part 29: The Scientific Process: Lead to More Questions (Alvarez)

-Late in 1983 two Chicago paleontologists, Dave Raup and John Sepkoski, offered evidence that during the past 240 million years extinctions have occurred about every 26 million years, - periodicity. -Alvarez showed these findings to Rich Muller, who believed these findings were valid and proposed that the Sun has a companion star that orbits, along with the sun, their mutual center of gravity every 26 million years -The hypothesis of Nemesis, a companion star to our Sun, the closest star to Earth, 2.5 light years away, that could affect the orbit of objects in the far outer solar system, sending them on a collision course with Earth to cause periodic mass extinction. -Only a small number of scientists thinks Nemisis exists. -"But only time will tell the real story."

Week 6 Part 10: Why were there negative reactions to Bohr's ideas initially?

-Lord Rayleigh (Nobel prize in physics 1904): "I saw it was no use to me." -O.W. Richardson (Nobel prize in physics 1928): "Although the assumptions conflict with dynamical ideas they are of a very simple and elementary character. The fact that they conflict with dynamics does not appear to be a valid objection to them." (Richardson The electron theory of matter 1914, p587) -The mechanism of such "quantum jumps" is not dealt with in the Bohr model of the atom. They just mysteriously happen.

Armand Fizeau and Jean Foucault

-Made the first precise non-astronomical measurements of the speed of light on Earth

Carbon

-Main atom in our body -All the organic molecules have carbon atoms inside

Week 2 Part 30: Scientific Attitude: Malvin Ruderman

-Malvin Ruderman, a proponent of the supernova theory, responded immediately to our preprint with a brief and pointed note. "Dear Luie," he wrote: "You are right and we were wrong. Congratulations." -Mal's response exemplifies science at its best, a physicist reacting instantly to evidence that destroys a theory in which he previously believed.

Week 11 Part 18: What did you learn from this course of quantum physics when it comes to everyday problem solving?

-To keep an open mind and follow the COMPLETE process of scientific inquiry, which is the essence of this class (Observation, Hypothesis, Experimentation, and Communication)

Week 2 Part 17: Falsifiability

-Many laymen apparently believe that scientific theories can be verified experimentally. -That's not true. Theories make predictions that can be confirmed, which leads to a theory's acceptance. -But most theories can never be proved, only disproved. Ex: Newton's famous theory of gravitation was eventually proved false by Einstein -Fundamental physical science involves observing how the universe functions and trying to find regularities that can be encoded into laws. To test if these are right, we do experiments. We hope that the experiments won't always work out, because it is when our ideas fail that we extend our experience. The art of research is to ask the right questions and discover where your understanding breaks down.

Week 2 Part 26: The Scientific Process: Theory Modified and Strengthened (Alvarez)

-Marine paleontologists disagreed with the proposed three years of darkness because so long a period would kill off most plant and animal life in the sea. (3-6 months) -Modified the theory that the asteroid or comet would vaporize itself and ten to a hundred times its weight of rock, and that the fine dust would fall over a period of three years, which would give the winds the power to transfer it worldwide -> dust would fall in a few months aided by computer simulations used by Brian Toons -Dust particles would collide and form larger particles, and fall faster and explained a more rapid transport mechanism which was lacking. -Clay layer with high iridium was found in many parts of the world.

Who were some of Max Born's Students?

-Max Delbruck, Nobel in Physiology or Medicine, 1969 -J. Robert Oppenheimer, theoretical physicist, Leader of the scientific side in Manhattan Project and was head of an institute in Princeton, political problems during Mccarthyism -Maria Goeppert-Mayer, Nobel in Physics, 1963 -Enrico Femi, Nobel In Physics, 1938, experimental physicist, Italian-American, was the first one to successfully perform the chain reaction right before we realized that it is possible to build the atomic bomb, director of the Fermi National Lab in Chicago

Week 5 Part 13: problem with classical theory and the quantized energy hypothesis

-Maxwell's classical electromagnetic theory predicts energy depends on intensity of light, but not color (frequency) of light, energy is spread out over a huge number of atoms. -Either increasing light intensity or shining for longer period would pop out more electrons, color of light should have no impact. -A fleet of boats is tethered off shore with firmly set anchors in a sea breeze. -Classical picture: All boats are waving smoothly in the wind with similar magnitudes. (energy is averaged out among all boats) -This is in direct contradiction to Hertz's experimental evidence.

Week 4 Part 1: What's ancient Greek's approach to problem solving?

-Metaphysics, the School of Athens -Aristotle: Physics, 350 B.C.E -The world can be understood Only by logic -Many schools of thoughts. -"The heavier the object, the faster it drops to the ground, the desire for rest at the cosmic center"

Week 9 Part 3: How is (and is not) waviness explained using the Born Rule?

-Most difficult to believe: PROBABILITY IS A FUNDAMENTAL COMPONENT OF NATURE -We can no longer make exact statements about the familiar positions and motions of things (ex: I know I can be back home by 3pm), we must be content with a probabilistic description of Nature. -The waviness in a region is the probability of finding the object in that region. -The waviness is NOT the probability of the object being there. -Because the quantum sets are so small, we can't tell in our everyday life. It is there but it is too small for us to see. -THE OBJECT WAS NOT THERE BEFORE YOU FOUND IT THERE. YOU HAPPENING TO FIND IT CAUSED IT TO BE THERE (collapse of wave functions)

Week 6 Part 17: Rutherford Ignored

-Most physicists would rather ignore Rutherford's occasional large-angle alpha scatterings than accept a radical violation of the Maxwell theory of electromagnetism. That cornerstone of physics had proven itself in every test. -Also ignored was that strange assumption Max Planck used to derive the formula for thermal radiation. -Albert Einstein was no exception, his "reckless" proposal to account for the ejection of electrons by light. -These outlandish ideas were ignored by most physicists. They assumed there would soon be more reasonable explanations.

Week 4 Part 27: Light is a wave

-Newton's particle hypothesis can not explain "a ping-pong ball + a ping-pong ball = darkness" -Young's constructive and destructive interference successfully explained the fringes around 1801. -About a decade later, a French physicist, Augustin Fresnel, confirmed and extended Young's results. and the idea of light as waves was established which led to the design ofmany refined optical instruments, from microscopes to telescopes, based on light waves.

Week 6 Part 18: Niels Bohr

-Nobel Prize in Physics 1922. -Completed his PhD in 1911 at the University of Copenhagen, Denmark -One who first showed the wide possibilities of the nuclear scheme of the atom in fields other than radioactivity -Bohr's scheme was based on the fundamental discovery of Max Planck, who first announced that radiation, such as light, was emitted not continuously, but in little packers of radiant energy, which he called quanta (singular, quantum) -Became a postdoc at Rutherford's lab in 1912. -Rutherford assigned him the job of explaining how the planetary atom might be stable. -It was Bohr's work that forced physicists and chemists to realize that quantum theory was of particular importance

Week 4 Part 8: What's Faraday's contribution to our society today?

Law of Induction: a changing magnetic field produces electricity. Invented the electric generator that powers almost all of our economy today.

Week 9 Part 9: What's the observer's (measurement) problem?

-Observation is a kind of measurement -By observing a system, we are also interacting with it and changing it -When we are not looking, it is a wave -When we are looking, it becomes a particle -The way we see light (colors) is what is reflected off an object, photons will have interacted with the object before they hit our eyes, so what we observed is an altered state. -Measurement will cause a collapse of wave functions, and they become dots/particles as a result of observation/measurement -Outcome: Everything is a wavefunction. Nothing is real until it is being observed.

Einstein's Second Challenge To The Uncertainty Principle Part 1: The Einstein Box

-Occurred at the Sixth Solvay International Conference in 1930 -A box contains electromagnetic radiation and a clock that controls the opening of a shutter which covers a hole. -The shutter opens the hole for triangle t with great accuracy .-During the opening, a photon escapes through the hole. -The box is weighed before and after the event, and energy of the photon is determined by E=mc square(2) -In conclusion, both time and energy can be determined simultaneously: the Uncertainty Principle is wrong.

Example Of Difference Between The Ordinary & The Quantum World: Glove in a tin example in the Robert Llewellyn video

-Ordinary World: To find out if a glove in the tin is right handed or left handed, you just need to take a look. We just revealed what nature already knew, what we are all used to. -Quantum World: Not as simple. Before we open the tin, there is an EQUAL CHANCE that the glove could be left or right handed.

Week 2 Part 25: The Scientific Process: Predict and Confirm (Alvarez) #2

-Our theory predicted that the relative abundances of siderophilic elements in the boundary clay would be the same as those for solar system debris, the most common of which is stony meteorites. -This was confirmed by R. Ganapathy. -Frank and Helen found abundance ratios for iridium, platinum, and gold that were consistent with those of meteorites but quite unlike those of any crustal rocks listed in the literature. -We predicted that the iridium enhancement would appear just above the highest (and last known) dinosaur fossils, not a speciesextinction. -Several orders of reptiles, including giant marine reptiles, went completely extinct. All land animals weighing more than fifty pounds disappeared from the fossil record.

Week 4 Part 3: What's the significance of Galileo's contribution to problem solving? #2

-Our theory predicted that the relative abundances of siderophilic elements in the boundary clay would be the same as those for solar system debris, the most common of which is stony meteorites. -This was confirmed by R. Ganapathy. -Frank and Helen found abundance ratios for iridium, platinum, and gold that were consistent with those of meteorites but quite unlike those of any crustal rocks listed in the literature. -We predicted that the iridium enhancement would appear just above the highest (and last known) dinosaur fossils, not a speciesextinction. -Several orders of reptiles, including giant marine reptiles, went completely extinct. All land animals weighing more than fifty pounds disappeared from the fossil record.

Difference between particles and waves Part 2

-Particles have a well-defined location in space at any time and moves on a trajectory unlike a wave, which is spread over space. -Particles have energy and momentum which can be transferred to other particles in collisions.

Difference between particles and waves Part 1

-Particles process the quality of discreteness -Take two glasses: one of water, and one of fine, dry sand. Both can be poured and swirled. -Can look similar if you don't look too closely, but the liquid is continuous and smooth while the sand consists of countable, discrete grains. -A small scoop will always pick up a volume of smooth liquid but only a countable number of grains of sand.

de Brogile Part 2: The Ph.D. Thesis (de Brogile)

-Paul Langevin needed help and sent the manuscript to Albert Einstein. -Einstein was not ambivalent. -Writing back, he called de Brogile's brief calculation "has lifted a corner of a great veil", and incorporated it into his quantum studies -de Brogile got his Ph.D.

Entire purpose of all 7 Experiments. Did we fail or succeed?

-Pin down the electron, know where they are in the process, and we failed. -We are no longer able to observe these electrons while maintaining any interference pattern on the backstop

Example of thermal radiation: Egg and water

-Place a cold egg in a pan of hot water -The cold egg will heat, absorbing energy from the water -The hot water will slightly cool down, yielding energy to the egg -After a while, the egg and water will have the SAME temperature

Week 5 Part 14: if Planck couldn't explain why his hypothesis worked, why is he scientific?

-Planck didn't really take his own theory seriously. He called it "an act of desperation." -But he is scientific because you can not change evidence!

Week 5 Part 35: Planck's Energy Quanta

-Planck's solution to the "Ultraviolet Catastrophe", which stated that the intensity of radiant light depends on both the frequency of color and the number of waves (energy quanta)-Blue waves (high frequency) take larger chunk of energy, the number of quanta is actually smaller in the same square.-Energy stops flowing continuously, but jumps in steps!

Week 9 Part 11: How to figure out probability using counting (and without a formula)?: Understand how ALL probabilities are calculated in the examples (on the slides), please do not memorize

-Probability equation: number of successful outcomes (top, numerator) divided by number of all possible outcomes (bottom, denominator) equals the probability of success -Construct all possible outcomes first -Ex: Coin: Probability go getting heads is 1/2 -Ex: Dice: probability of getting 2: 1/6 -A coin or a dice has an equal chance of landing on each side. -Look at first few slides of 4/9/20 on your phone, and spend time trying to understand them as much as possible! -"And" in probability equations: Means to multiply -"Or" in probability equations: Means to add

Week 9 Part 17: Malus's law (cosine) itself is not required but the conclusion is important (probability is ¼ at 120 and 240 degrees), what he says "Number of photons/energy passing polarizer 2 is close square 2 (0 with line in the middle)" and how it is used to calculate overall probability of light passing two polarizers.

-Probability is ¼ at 120 and 240 degrees Polarizer 1: 0 Polarizer 2: 45 degrees, with a probability of 1/2 Polarizer 2: 90 degrees Polarizer 2: 120 degrees, probability 1/4 Polarizer 2: 240 degrees, probability 1/4 -If polarizers are perpendicular to each other, you get no light coming out of the second one. -Look at picture on slide: Probability of Photons Passing -0 with line in the middle is angle between the Two Polarizers (1st one is vertical and 2nd one is horizontal). Incident Beam (unpolarized). They make up a vertically polarized light wave. -Angle is 90 between Polarizer 1 (0 degrees) and Polarizer 2 (90 degrees) because they are perpendicular to each other

Week 11 Part 7: Understand the similarities and differences among the classical, semi-classical and quantum Alice and Bob thought experiments: Quantum

-Quantum analogy: Instead of gloves being sent to the galaxies, a pair of polarized photons are sent. Alice (10 million light years) is closer to Earth to Bob (15 million light years), so she receives her photon first. -There is only one type of photon (part horizontal and part vertical), a superimposed state, where the orientations of the pair are always the same, but no one knows if it is horizontal or vertical before they are measured -Photons are not physical reality, and we don't know which way they are going. -Like the last two experiments, Alice gets her photon (which is vertical or horizontal) first and she immediately knew Bob's would be the same -EPR: impossible for Bob's photon, 20 million light years away, to have been mechanically distributed by Alice's photon. Nothing can travel faster than the speed of light. The only way to change Bob's state is hidden variables. -EPR: There is reality for Bob before being observed -Copenhagen Interpretation: Even if Alice knew the orientation, it does not mean Bob knew his, meaning there is no physical reality for Bob.

Week 4 Part 13: What are the radiation types in the electromagnetic spectrum?

-Radio, Scale of frequency: 10 over 3, Approx. Scale of Wavelength: Buildings -Microwave, Scale of frequency: 10 over -2 Approx. Scale of Wavelength: Between Humans and Butterflies. -Infrared, Scale of frequency: 10 over -5 Approx. Scale of Wavelength: Needlepoint -Visible, Scale of frequency: 0.5 x 10 over -6 Approx. Scale of Wavelength: Protozoans -Ultraviolet, Scale of frequency: 10 over -8 Approx. Scale of Wavelength: Molecules -X ray, Scale of frequency: 10 over -10 Approx. Scale of Wavelength: Atoms -Gamma ray, Scale of frequency: 10 over -12 Approx. Scale of Wavelength: Atomic Nuclei

Week 4 Part 16: How we see colors, what are the early ideas about light, who were the main players

-Robert Hooke (1635-1703) English Physicist -In 1672 Robert Hooke offered a wave theory to explain diffraction, the bending of light rays around corners. -It is called single slit diffraction. -Squint your eyes at a light source. -Among many things, Newton was interested in light. -Much of the history of physics can be written as a history of the nature of light. -Isaac Newton's Corpuscles Theory -Newton's particle hypothesis can not explain "a ping-pong ball + a ping-pong ball = darkness"

Who were the four key pioneers of quantum physics?

-Schrodinger and Heisenberg (first two) -Third was Paul Gerock, who in 1930 incorporated Einstein's relativity into quantum physics. -Last was Richard Feynman, awarded the Nobel Prize in 1965. Along with two other physicists, Feynman completed the grand theory of quantum physics.

Week 7 Part 7: Schrödinger's initial attempt to explain what wave functions mean

-Schrodinger described electron-in mathematical terms-as a wave and argued particles were a new type of wave: a matter wave -Elections move from one form of vibration to another

Week 9 Part 8: What's wrong with Schrödinger's original interpretation of his wavefunctions?

-Schrodinger speculated that an object's waviness was the smeared out object itself. The electron itself would thus be smeared over the extent of its waviness as it goes through the double slit. But it is wrong -We don't have any electrons, we have smeared out electrons -No, that doesn't work. Einstein made it very clear, there will be no partial photons (electrons) -How could an electron be a particle localized in space and at the same time a spread out wave?

Week 7 Part 5: Schrödinger's reaction to the Bohr model

-Schrodinger's trouble with Bohr's atomic model: while electrons moved only in "allowed orbits" and then, without cause, abruptly jumped from one orbit to another. -Stated to Bohr that the "whole idea of quantum jumps necessarily leads to nonsense". He claimed that "according to Maxwell's theory, it must radiate." -Did not like quantum jumps, he did not like that Bohr was not able to explain why these electrons are only allowed on some orbits, not all.

Week 2 Part 28: The Scientific Process: Confirmation Bias (Alvarez)

-Some earth scientists complained that we have looked for iridium only where there are extinctions and that we might otherwise find it elsewhere, perhaps everywhere, in the geological record. -Extensive tests are required, thanks to technology improvements on sensitivity and speed (from a full weekend to 7 minutes per sample) -Followed Ernest Lawrence to share the "know-how" with scientific community -Frank and Helen have searched through long stretches of sediments and have found iridium at the level of only thirty parts per trillion elsewhere than at extinction boundaries, the amount expected from the steady infall of meteoric dust.

Week 8 Part 3: What's the "surprise" of Experiment 6?

-Sometimes we hear a click from the detector/backstop but see no flash at either 1 or 2. The electron has gone by without being "seen". -Now lightbulb is not "bright" enough -We did not see all 100 electrons, we miss some, we need to find a way to fix that. -We add a third column to try again -1 and 2 are reproducible this time, we add them up and get a bump but only for 1 and 2. What about 3? -3 has the interference pattern but is seen by neither, we don't know which opening the electron goes through because the light is too dark and we can't observe them. -Observed: Nice bump, electrons behave like particles/bullets -Unobserved: Interference pattern, electrons behave like a water wave

Week 5 Part 6: wave theory of light

-States that light consists of a series of waves rather than individual particles -Stated that light is emitted as the vibrations (very fast, thousand trillion cycles per second) of atoms

Overall view On Quantum Theory About the World

-States there is an absolute limit to what we can know about what goes on in nature at the atomic level -States the universe is run on chance, nothing is certain -It's the theory that predicts how the world behaves at an atomic level, and it gave birth to a second industrial revolution with the invention of modern electronic devices

Week 2 Part 10: What were the original results of the first hypothesis?

-Supernova nucleosynthesis calculations predicted the Pu-244-to-iridium ratio that Frank and Helen quickly detected. -Alvarez telephoned the president of the National Academy of Sciences and asked him if I could describe our discovery at the next annual meeting, which would celebrate the U.S. Geological Survey's hundredth anniversary. He put me on the program and congratulated us

Probability of Getting a Vertical Photon Part 1 (Set-up)

-Suppose Polarizer 1 is always vertical, and Polarizer 2 can only be at positions A, B, and C randomly with equal chance. They are 120 degrees apart from each other. -Probability : 1/4 for the first two, probability is 1 for the last one. -Turn polarizer 2, which has an equal chance of landing on A, B, and C each. -What is the probability of getting a vertical photon after polarizer 2? (probability of a vertical photon at A or B or C)

Week 5 Part 37: The Reception of Einstein's Photon Hypothesis

-Ten years after Einstein's work on the photoelectric effect, the American physicist Robert Millikan said in 1915 that Einstein's photon hypothesis is "wholly untenable" and "reckless". -The physics community received the photon hypothesis "with disbelief and skepticism bordering on derision". -When Einstein was proposed for membership in the Prussian Academy of Science, Planck in his letter of recommendation asked that Einstein be pardoned for his photons; he wrote: " ... that he may sometimes have missed the target in his speculations, as, for example, in his hypothesis of light quanta, cannot really be held too much against him ... "

Week 11 Part 1: The EPR Paradox, Bell's Theorem What are the main arguments of the EPR Paradox?

-The EPR Paradox (gedanken experiment) was Einstein's third attempt to challenge the uncertainty principle and fault quantum theory -Along with two other young colleagues (Boris Podolsky and Nathan Rosen), the paper was published 1935 -The two main arguments of the EPR Paradox 1. Physical Reality: If a property can be measured without "disturbing" it, then we can predict it with certainty. There is reality that is not observer created. 2. Locality: Information can only travel from A to B by going through every point in space, one at a time. Nothing can travel faster than the speed of light. There is no instant effect at a remote place, or there is no "spooky action at a distance" -If there is physical reality and locality, then quantum theory is incomplete. If a theory is incomplete, there must be "hidden variables", which are unseen influences that affect the outcome of events. -In response, Bohr published a paper with the exact same title ("Can Quantum Mechanical Description of Physical Reality Be Considered Complete) Answer: Yes

Week 11 Part 4: Explain the determinism using "hidden variables" to explain the tossing of a coin

-Tossing a coin and describing its motions... -It is a very complicated motion, it is nonetheless possible to describe it by physics laws precisely. -Classical physics: We can definitely describe the motion of this coin but it is so complicated

The Uncertainty Principle

-The complete theory of quantum mechanics which we now use to describe atoms and, in fact, all matter depends on the correctness of the uncertainty principle. -A fundemental cornerstone of quantum theory -Since quantum mechanics is such a successful theory, our belief in the uncertainty principle is reinforced. -But if a way to "beat" the uncertainty principle were ever discovered, quantum mechanics would give inconsistent results and would have to be discarded as a valid theory of nature. -The Uncertainty Principle saves the quantum theory -Not final, not saying it is correct, but the more evidence we have, the more confident we are about this principle.

Week 8 Part 15: Uncertainty Principle

-The complete theory of quantum mechanics which we now use to describe atoms and, in fact, all matter depends on the correctness of the uncertainty principle. -A fundemental cornerstone of quantum theory-Since quantum mechanics is such a successful theory, our belief in the uncertainty principle is reinforced. -But if a way to "beat" the uncertainty principle were ever discovered, quantum mechanics would give inconsistent results and would have to be discarded as a valid theory of nature. -The Uncertainty Principle saves the quantum theory. -Not final, not saying it is correct, but the more evidence we have, the more confident we are about this principle.

ultraviolet catastrophe

-The contradiction between the classical model of blackbody radiation with experimental results in the early twentieth century; resolved by the Planck hypothesis -The supposed preference for the ultraviolet doesn't occur in the data. -If it did, fires wouldn't glow red at lower temperatures, they would glow blue

Momentum

-The force or speed with which something moves -A significant characteristic of the motion of matter -For photons, the momentum is the energy divided by the velocity of the light, c. -This is an important concept because the total momentum of all the objects about to collide is conserved. -Quantity that describes a property of an object -Momentum mv: particle property

Week 5 Part 34: Planck's Formula

-The fundamental thing about the quantum of radiant energy is that its size depends upon the frequency of the radiation in question. -In fact, the size of the quantum of energy of a particular radiation is the frequency of the radiation multiplied by a very small number, always denoted by h, called Planck's Constant. -It is for this reason that the frequency was said earlier to be the fundamental characteristic of radiation. Thus the quantum of X Rays of a certain frequency is much larger than quantum which is characteristic of a particular kind of visible light -It it as if we can only buy things at a fixed unit of price Ex: 12 quanta of diamonds: $1200, 12 quanta of squashes: $1.20 -The concept of radiant energy in packets, of which is very proportional to the frequency, may seem strange but it is deeply involved in modern atomic theory -Planck hypothesized that energy comes not smoothly, but in lumps, it depends on frequency (color) ΔE = hf -Planck chose a number for h which gave the best fit with the experimental data .-We now call this number "Planck's constant", a new fundamental constant of the universe. h = 0.00000000000000000000000000000000067 joule-seconds = 6.7 x 10-34 joule-seconds

Week 5 Part 10: black body radiation Part 1

-The generic pattern of the electromagnetic radiation that all systems have in common when they are simplified, or so well-blended together that the special atomic color effects get avenged out. -Thermal radiation is also called and produced by black body radiation, the study of this was a rich new subject that conjoined two fields of physics: 1. The study of heat and thermal equilibrium 2. The study of light in radiation

Week 6 Part 4: Rutherford gold foil experiment, miniature solar system hypothesis and its problems

-The gold foil experiment in Manchester University laboratory in England in 1909. -Shooting positively charged alpha particles at a thin gold foil. -Prediction by the plum pudding model: all alpha particles should always go right through. -A chance of 1 out of 8000 -Rutherford: "It was as if you fired a fifteen-inch artillery shell at a piece of tissue paper and it came back and hit you." -That was when Rutherford realized that there must be a positively charged massive core at the center of an atom, the (very small) nucleus. -Rutherford's estimate: the nucleus is about 1/8,000 of an atom in radius (length) Just how small is the nucleus compared to an atom? -If the nucleus was the size of a dime (0.7 inch or 18mm), how big would an atom be? -The radius of an atom would be 0.7 inch x 8,000 = 5,600 inch = 467 ft The size of the Yankees Stadium-Can you verify one trillionth of the volume? 8,000 x 8,000 x 8,000 = 512,000,000,000: The nucleus was one trillionth of the atom, even though 99% of the mass' atom was in the nucleus -Matter and most of the atom is mostly empty space! (Ex: The solid chair you sit on is overwhelmingly composed of nothing)

Week 6 Part 21: The Acceptance of Bohr's Model

-The intuitively reasonable laws of classical physics worked unfailingly in the heavens and for all on earth one could actually see. It was a complete and beautiful system. -Bohr's proposed modification went against all scientific intuition: Energy in an atom is "quantized". An object could orbit only at certain distances--and no others. -Truly new science always involves an inspired guess (hypothesis). It can be a completely new law of physics. It has to satisfy a single criterion: -Every prediction of the new law must be supported by experiment.Bohr's theory offered precise prediction, same as -Newton's Laws. It's hard to argue with that kind of striking success. -Most physicists gave up trying. Many looked to Bohr for guidance.

Week 7 Part 3: The historical development of wave-particle duality

-The observation that quantum-scale objects such as subatomic particles exhibit properties of both particles and waves -de Brogile tried to come up with an idea of how to measure the wavelength of a matter wave. -Electron is a particle, moving around in an atom 3,000 meters per second, close to 9,000 feet per second (very fast) -How de Brogile came up with the idea of the wavelength of a matter wave is unclear. He never revealed it. -One possible thought process is: fundamentally, an electron has mass and velocity, since this is a quantum phenomenon, it should also have the Planck's constant, and the formula must result in length, meters.(Look at picture of slide 3, 3/25/20, on your phone) PH'D Thesis -de Brogile's theory was revolutionary at the time because nobody was thinking of wavelength of electrons, atoms, etc. They were just little particles, not extended waves in space like water waves. -de Brogile's "new physics" (called that because everything we call particles are also waves) was more objectionable than Bohr's. It seems so arbitrary to the consensus of the scientific community in the 1920s.

Week 11 Part 16: Probability & Nature

-The only way to explain nature is by probability and the only way out of the conundrum The best bet is to follow the scientific method. According to Issac Asimov, "so the universe is not quite as you thought it was. You'd better rearrange your beliefs, then. Because you certainly can't rearrange the universe."

Week 10 Part 5: What's the debate at the 1927 Solvey Conference? How did Einstein challenge the Copenhagen Interpretation?

-The physics community was divided in two camps: one who believed in the uncertainty principle (led by Bohr and Heisenberg, and one who doesn't believe in the uncertainty principle (led by Einstein and Schrodinger)

Week 5 Part 3: Frequency

-The rate at which crests or troughs pass a given point in space -Speed of light divided by its wavelength

Week 5 Part 9: Color of thermal radiation and temperature

-The red-hot wire in the toaster -the glowing coals in the fire -But you are watching a quantum phenomenon! -The sun all radiate electromagnetic energy because they are hot. -High school chemistry lab: The Bunsen Burner -Color -> Frequency -> Temperature

Color of thermal radiation and temperature

-The red-hot wire in the toaster, the glowing coals in the fire -But you are watching a quantum phenomenon!the sun all radiate electromagnetic energy because they are hot. -High school chemistry lab: The Bunsen BurnerColor -> Frequency -> Temperature

Week 10 Part 3: Understand all details of the Schrödinger's cat thought experiment.

-The set up is that the radioactive material will decay by releasing some kind of particle. In order to detect these particles, with a Geiger counter, but in this case, instead of triggering the Geiger counter, you will actually trigger a hammer, breaking the glass bottle of cyanide (poison), killing the cat -There is a 50/50 chance that one of the atoms in the radioactive material will decay and that the detector (a Geiger counter) will record a particle. -The decay process is a pure quantum phenomenon -According to the Copenhagen Interpretation, a radioactive atom is in a superposition of states of both decayed and not decayed, a glass vessel of poison that is neither broken nor unbroken, and a cat that is BOTH DEAD AND ALIVE, NEITHER ALIVE NOR DEAD. -We have NO WAY OF KNOWING THE OUTCOME OF THIS EXPERIMENT UNTIL WE OPEN THE BOX TO LOOK INSIDE -Just as in the two slit experiment, there is an equal probability that the electron goes through both slits, and the two overlapping possibilities produce a superposition of states. Experiments would later show that Schrodinger's cat would indeed exist in a a mixed states, so quantum physics triumphs once again!

Waves Of Probability

-The single electron interference is formed by individual flashes on the screen. -Where each electron hits on the screen cannot be determined, we are only allowed to calculate the probability of hitting a particular spot -With probability, comes the weird quantum effect: walking through a wall

Week 9 Part 2: The Born Rule/Waves Of Probability Part 2

-The technical expression for the probability is the "absolute square of the wave function", or amplitude. it is the probability of finding the object in that region. i over 2 (square) = -1 -All of a sudden, the square (-1) had a meaning -Born was the first to realize that if you can square the wavefunction, you can actually picture it -Everything we deal with is a PROBABILITY-THE BORN RULE ENDED THE DETERMINISM OF QUANTUM PHYSICS -Look at picture on your phone with slide of the same name for equations, April 8 2020

Reaction to Schrodinger's Wave Mechanics

-The work was instantly recognized as a triumph and solved a lot of problems -Possibly accelerated the progress of quantum physics -Was very convenient for physicists to use and could be applied to any system requiring a quantum treatment -It gave the correct values of the vibrating energy levels of the electrons in an atom, which emits light of definite energy (the spectral lines of light) and these are now seen to be associated with the electrons hopping from one vibrational wave state of motion to another. -Einstein said it sprang from "true genius" -Planck called it "epoch making" -Schrodinger himself was delighted to think that he had gotten rid of quantum jumping. -However, there were still a lot of people that were doubtful of Schrodinger's equation.

Week 2 Part 9: Original hypothesis Of Luis and Walt Alvarez

-Their mystery: the origin of the clay layer iridium appeared to be extraterrestrial. -They first guessed that it had come from a nearby supernova explosion. -Since elements heavier than nickel are believed to be made in the neutron-intense environment of stellar explosions, other heavy elements should have been present in anomalous amounts in the boundary clay. -Key isotope to look for: Plutonium 244, which had a half-life of 75 million years, andterm -59 had decayed away in ordinary rocks formed 4.7 billion years ago

Difference between theoretical and experimental physicists

-Theoretical: Works on theories and does not do experiments -Experimental: Does experiments

Week 11 Part 15: Understand how the probability is calculated for a given instruction set: The Bell Inequality

-There are eight possible outcomes 1. ABC arrow RRR 2. ABC arrow GGG 3. ABC arrow RRG 4. ABC arrow RGR 5. ABC arrow GRR 6. ABC arrow RGG 7. ABC arrow GRG 8. ABC arrow GGR If all instruction sets are chosen randomly (1/8 each), the overall probability of flashing the same color is: (1 x 1/8) + (1 x 1/8) + (5/9 x 1/8) + (5/9 x 1/8) + (5/9 x 1/8) + (5/9 x 1/8) + (5/9 x 1/8) + (5/9 x 1/8) = 2/3 -According to John Bell, if there are hidden variables as claimed by Einstein in any instruction set scheme, the detectors will flash the same color with probability 5/9: 55.5% or greater than equal to 55.5% -Anything less than that will violate the inequality, therefore there would be no hidden variable, meaning Einstein would be wrong. -The only way to confirm this is to do experiments, which were done by John Clauser, Alain Aspect, and Anton Zeilinger. Their work on the Bell Theroem proved Einstein wrong, and Bohr right.

Ex: of how Quantum theory is a superset of classical theory

-This means quantum theory can describe everything Newton's laws describe and also can't describe -But it cannot describe how electrons move. -Newton's laws can only cover certain parts of nature but is cannot describe everything in nature

Max Planck's inspired formula in simplest "the energy of quantum light is directly proportional to its frequency"

-This means that electromagnetic radiation comes out in lumps such that each "lump" has an energy equal to some constant, h, times the frequency -The total intensity of light at any given frequency is the number of quanta that are being detected at that frequency times the energy of those quanta -When you plug in Planck's equations and dialed the given temperature, the predicted blackbody curve agreed precisely with the data

Week 4 Part 19: Thomas Young Part 1

-Thomas Young's most famous was the double slit experiment-a demonstration that light and matter can display characteristics of both classically defined waves and the first of many illustrating the wave property of interference. -It also produced data that was inconsistent with Newton's concept of light as "corpuscles" (stream of particles) -Young, realizing this, prefixed his arguments with selections from Newton's old writings that expressed some doubts on the subject of the wave vs. particle model

Differences between Schrodinger and Heisenberg's processes for coming to the same conclusion

-Unlike Schrodinger's "Wave Mechanics" (in which we can use waves to picture what's happening), Heisenberg's "Matrix Mechanics" was an abstract mathematical method (you cannot picture it when you calculate it) for obtaining numerical results. -It denied any pictorial description of what was going on.

Week 6 Part 6: Quantitative understanding of the Balmer series and it's predictions

-Wave numbers: number of waves in a centimeter (cm) -1 meter = 109 nanometer, therefore 1 cm = 107 nanometers (1 cm = 107 nm) -The 1st line(n=3): 109,677x(1/4 - 1/9)=15233 (cm-1), wavelength ƛ = 107/15233 = 656 (nm) -The 2nd line(n=4): 109,677x(1/4 - 1/16)=20564 (cm-1), wavelength ƛ = 107/20564 = 486 (nm) -The 3rd line(n=5): 109,677x(1/4 - 1/25)=23032 (cm-1), wavelength ƛ = 107/23032 = 434 (nm) -The 4th line(n=6): 109,677x(1/4 - 1/36)=24372 (cm-1), wavelength ƛ = 107/24372 = 410 (nm) -Balmer also predicted another line at 397 nm (n=7), which was discovered by others. -Look at picture on your phone

Week 5 Part 8: Wavelength and Frequency of Light

-Wavelength measures length from peak to peak. -Frequency (Hz) measures number of waves per second (how many time it vibrates in 1 second) -Frequency (cm-1 wavenumbers) = measures number of waves in 1 cm -Speed of light is constant at 300,000,000 meters/second -1 nanometer = 10-9 meter -Amplitude is the height of a peak above zero. -Shorter wavelength = higher frequency = higher energy -Longer wavelength = lower frequency = lower energy

Week 4 Part 18: Wavelength frequency and d amplitude, colors and their relative frequencies

-Wavelength: length of a wave (red laser 680nm, 1 nanometer=0.000 000 001 meter) -Speed of light = wavelength x frequency -Frequency: number of waves per second, same as energy, -frequency=speed of light/wavelength = 300,000,000 (m)/0.000 000 68(m)=440,871,261,764,706 or 4.4x1014, about 440 trillion times per second -Speed of light is constant (Einstein) -Red color: low energy, long wavelength (680 nm). -Green color: high energy, short wavelength (520-570 nm)

How do we bring waves and particles together?

-Waves: All spread out in space everywhere -Particle: Localized dot and position, only over one small area

Week 11 Part 19: Another Example of Bell's Theorem

-We gaze into a tropical aquarium with several fish species -We soon notice that every fish has one of two colors: red or blue -From a logical point of view, this is "binary", either a fish is blue or not blue and not blue is equivalent to red and vice versa -We soon further notice that every fish, while either blue or red, is also either large or small -We then see each fish has spots or no spots. -We have three binary attributes here now: red or not red, large or small, spots or no spots. -Theorem: The number of red fish that are small, plus the number of big fish that are spotted is always greater than or equal to the number of red fish that are spotted.

Week 2 Part 23: The Scientific Process: Postdictions (Alvarez)

-We predicted that the boundary clay should show signs of exceedingly high temperatures and pressures from the impact shock (these were actually postdictions; they followed directly from the theory. but we hadn't the temerity to articulate them before other groups observed them). -The shocked quartz convinced the few remaining geological skeptics; it was evidence they understood and found persuasive. -Additional supporting evidence previously unsure.

Week 2 Part 24: The Scientific Process: Predict and Confirm (Alvarez) #1

-We predicted that the boundary clay was different from the clay in the adjacent limestones above and below, which we said would be identical. -We predicted that the iridium enhancement would be seen worldwide, as were the boundary clays and extinctions. -By 1986, iridium enhancements had been found at nearly one hundred sites by nine groups, and only at two or three paleontologically defined K/T boundaries was there no iridium.

How To Explain Quantum Behavior?

-We start with classical intuition using everyday objects (7 behavior though experiments) -We started with a classical intuition in Experiment 1, then water waves, and migrated towards microscopic objects -Then we use that to try to understand how quantum objects behave, moving away from classic objects, and we realized there are new laws of nature -The new laws can describe both quantum and classical behavior consistently, there are no exceptions so far -We were seeing strange behaviors (sometimes electrons behave like a wave, sometimes they behave like particles) .-Thanks to quantum theory, we are able to calculate/predict everything we were not able to see before but we still have problems -We need to give up classical behavior all together and accept this new theory, which is a superset of quantum physics. No conflict between the two. Quantum physics can describe everything quantum physics can't. (Ex: Baseball, de Brogile wave, wavelength, etc) -A consistent way to explain all that is PROBABILITY, which took many physicists a long time to understand what it really means.

Week 8: Part 1: Light is Uncertain The impact of "looking" how does it happen and what's the effect?

-We understand how we see things, but what really happens during the process? -A photon (electric field of light) kicks an electron (Compton effect). So if we shine a light on an electron, there are photons hidden in electrons. The light kicks the electron somehow, to some extent. -We have changed the photon or electron's motion by observing it Ex: If a chair is red under the sun, it means all other colors are absorbed, except the red color, which is reflected into our eyes.-Our eyes can only see the red color

Week 7 Part 4: Experiment 4, single electron interference

-We use a single electron at a time, and later on, scientists use a single photon at a time -Originally, when shooting one electron at a time, you get only random dots -But as time goes on, you get more electrons/dots, less random but most are still random on screen B -But as time goes on, we see dots everywhere but they are mapped out through the whole screen, making then even less random and giving us interference patterns. Its almost like they know where they should land. -Only 1 electron throughout the entire apparatus, through the double slit experiment. We have two openings instead of shooting bullets -Electrons are shot one at a time, so there should 1 electron in the system in the entire process. -On the righthand side of the screen, we see one dot (particle) at a time

square root of (-1) (Schrodinger's Wave Functions)

-We use it to represent that quantity and it still doesn't make sense that a negative value cannot have a square root -Anything that's squared cannot be negative

After the Born Rule, Physics now deals with what as a fundamental element of a physical theory

-What=probability -We now simply can't make exact statements about position and motion

Week 8 Part 8: What is Bohr's Principle of Correspondence? Part 2

-Whatever quantum physics predicts, it has to agree with the microscopic world -Bohr did not specify how large is large, but physicists take the view that whenever the Planck constant h has a negligible effect, it is considered a classical system -Bohr and Heisenberg did not specify what is considered microscopic, still not clear to this day. -Ex: baseball is about 0.145 kg (classical), where an electron is about 9x10 over -31 kg (quantum) -Because of the vagueness, scientists are now trying to test the boundary.

Week 5 Part 11: blackbody radiation Part 2

-When heated, emits only thermal radiation and gas none of the special color effects of fireworks -A physicists idealization that everyday objects can only approximate -These would become clues for the establishment of the quantum properties of light and the atom -Blackbody -Approximation -All objects radiate and absorb energy from their surroundings and the higher the object temperature, the greater the amount of energy it radiates, happens even if you lie on a beach on a hot day

Week 10 Part 1: Cat under the Light, Einstein's Challenges Understand why tunneling effect happens, how it is explained by quantum physics. (hint: it is not that some electrons with higher energy can go over the wall, electrons with energy lower than the wall, thus impossible in the classical world to go over the barrier, can go through the wall), calculations are NOT required.

-When throwing an electron at a wall, the electron would bounce back if the wall is thick, which seems normal -But the electron is a quantum particle and also behaves like a wave -The electron may be found on both sides of the wall if it is thin, which means that electrons can sometimes go through the wall. This is not possible in the classical world.

Week 2 Part 31: Scientific Attitude: Phil Abelson

-When we sent the paper to Science, Phil Abelson, the editor, returned it. -It was too long, he said, and Science had published several papers in recent years purporting to explain the K/T extinction. -"At least n-1 of them must be wrong," Phil remarked. -He finally agreed to publish a shortened version of our paper, a courageous decision that earned our gratitude.

Example of thermal radiation: You lying on a hot sunny day

-When you lie on beach on a hot sunny day, you are radiating and absorbing electromagnetic radiation -There is energy radiated to you by the sun -Your body adjusts and throws off energy to maintain the correct temperature (98.6 degrees) You continuously radiate about 100 watts of energy in your surroundings -Your body maintains a thermal equilibrium to sustain the chemistry of life -If the outside world is very cold, your body need to produce or retain more energy -If the outside world is hot, the body must throw off radiation to keep. Sweat absorbs additional thermal energy out of the skin and provides a kind of air-conditioning effect while transferring the energy to the outside atmosphere.

Why quantum theory is one of the best theories discovered by scientists

-While we can only use quantum physics to describe a small world and cannot use to describe how cars are moving, it is not always the case in physics -Literally all other theories, except quantum, has been updated within the last 100 years -We are still very far from a grand theory that can explain everything, making quantum physics an exception.

Week 11 Part 2: Bell's Theorem (John Stuart Bell)

-With this, John Bell found an experimental way of solving the problem if whether or not there were hidden variables in quantum physics. -Called "the most profound discovery in science in the last half of the twentieth century" -As a result of Bell's Theorem and the experiments it stimulated, a once purely philosophical question could now be answered in a lab. By the 1970s, work motivated by EPR showed that Einstein's "spooky interactions" actually do exist. Einstein was wrong -Any objects that have ever interacted continue to instantaneously influence each other. Events at the edge of the galaxy influence what happens at the edge of your garden. -When the paper first came out in 1964, experiments to test them were not available until the 1970s.

Week 7 Part 6: The historical narratives of the Schrödinger equation Schrödinger's initial attempt to explain what wave functions mean

-Wouldn't it make more sense to say that part of each electron goes through each slit if the electron can split into two? -Schrodinger speculated that an object's waviness was the smeared out object itself. The electron itself would thus be smeared over the extent of its waviness as it goes through the double slit. But it is wrong -We don't have any electrons, we have smeared out electrons -No, that doesn't work. Einstein made it very clear, there will be no partial photons (electrons) -How could an electron be a particle localized in space and at the same time a spread out wave? -Most accurate explanation: There is no electron, but only Schrodinger wave function of a electron. -The wave function goes through both slits. We call that the different parts of the wave function are in superposition. No electrons, just wavefunction.

Week 4 Part 20: Thomas Young Part 2

-Young's constructive and destructive interference successfully explained the fringes around 1801. -He stated, under certain circumstances, adding two beams of light can result in darkness-destructive interference when a wave crest adds to a trough. This a classic feature of an interference pattern, and it screams "wave phenomenon" -Concluded that under certain circumstances, adding two beams of light results in darkness

According to quantum physics,

...WE WILL NEVER UNDERSTAND THE FUNDAMENTAL LEVEL OF THE UNIVERSE -Our language is not enough to allow us to describe what we observe in our experiments.

Multiply the wavelength by the vibratory frequency...

...and you get the velocity

We see most objects around us, not because they emit light, but...

...because they reflect life and this reflection is imperfect except for a smooth mirror. -Ex: A red object reflecting white light from the sun reflects only the red part and absorbs the rest

The energy content of light according ti Maxwell's classical theory...

...depended on only the intensity, not the color or frequency

In many factors of science, everything remains the same while...

...one factor changes

Colors are the...

...physiological effect of the wavelength of light absorbed in the retina

Bohr insists...

...that the lack of physical reality is the ONLY consistent way to explain quantum physics

In this class, we are learning...

...the essence and history of quantum physics

If the Schrodinger Equation predicts 90% of the wave is reflected & 10% transmitted...

...this means out of a thousand electrons, something like 900 will be reflected and 100 transmitted

If you are puzzled, according to Bohr,

...you start to get quantum physics

Week 1 Part 3: The four goals of this class: Scientific Inquiry

1. Basic understanding of the fundamental concepts of quantum mechanics (the weirdness) 2. Milestones of the history 3. Scientific inquiry and the interplay of its variousaspects 4. The power of reason in everyday problem solving

Week 5 Part 39: Assumptions (which were against the accepted or classical) of the laws of electromagnetism (Bohr's Model Of The Atom, who adopted Rutherford's nuclear atom)

1. Electrons circulating in these orbits did not radiate 2. Of all the infinite variety of orbits that were permitted by the classical laws, only certain widely separated ones were actually possible, these possible ones being determined by a special quantum condition. An atom in which the electrons were all circulating steadily in orbits allowed by this condition were said to be in a stationary state. -Various definitely different stationary states could occur, according to which of the permitted orbits were actually occupied Ex: If a sparsely inhabited country automobiles are only allowed to drive along certain roads, this does not mean all the legal roads must necessarily have traffic in them.

Rydberg's Constant

109,677 The wave number of the first line of the series is, to five figures, 15,233

Week 9 Part 15: How to figure out probability using counting (and without a formula)?: Understand how ALL probabilities are calculated in the examples (on the slides), please do not memorize

180x20= 3,600, Theo. average is 100 -Yellow sample: 3,600 trials, 180 rolls, just keep counting for each number -Probability of 1/1=108, which is equal to the number of possible outcomes -13/360 = 1/36 -Ex: Probability of rolling a 1 first and a 5 second, 36 possible scenarios (red). 89/3,600=number of successful outcomes 89/3,600=1/36, 36 right numbers Probability of always rolling a 1 first: 1/6 Probability of never rolling a 2 first: 5/6 Rolling a two digit number between 20 and 39. 1/3 Rolling a number that is either a 2 or 6: 16/36 or 20/36: Ask Patty

Week 5 Part 4: harmonic wave

A regular cyclic change in the position of something that continually repeats itself-starting from 0, rising to a peak, then sinking through 0 down to a trough and back up to 0. A wave.

Week 4 Part 4: What's Newton's contribution to problem solving?

A theoretical framework (a refined hypothesis) and prediction, confirmed in nature.

Week 6 Part 7: The Bohr model, its hypotheses, how it explains the transition from quantum world to our everyday world Part 1

Bohr's Atomic Model -Electrons circulating in these atomic orbits do not radiate. -Allowed States: electrons are only allowed on certain orbits. -Light is released or absorbed when electrons jump to a different orbit. The frequency of the radiation was given by the difference of energy between the two stationary states. ΔE = hf -There was a smallest possible orbit. Electrons do not crash into the nucleus, atoms are stable. -Bohr calculated RH only using basic physics constants. -The predicted frequencies agree exactly with experimental observations. -Energy does not change continuously, it only jumps. -Those allowed orbits cannot be anywhere else, has to be either step 1 or 2, it can't be in between -Works beautifully cause it allows Bohr to calculate the frequency of these spectrum lines, spectral lines, which agreed exactly with experimental observations/measurements.

Week 6 Part 8: The Bohr model, its hypotheses, how it explains the transition from quantum world to our everyday world Part 2

Bohr's Energy Levels - Quantum Behavior -When n is small, closer to the nucleus: -A photon can be either emitted or absorbed by an atom. The electron jumps downstairs/upstairs. -The energy of the photon must exactly match an energy difference between the initial atomic state and some higher state. - no partial photons as per Einstein Bohr's Energy Levels-Classical Behavior -When n is large, away from the nucleus: -The gaps of quantum jumps decrease between lines, energy is continuous at high level, transition from quantum to our everyday world. -No more "quantum jumps".

Week 10 Part 7: What's the debate at the 1927 Solvey Conference? How did Einstein challenge the Copenhagen Interpretation?

Bohr's Reaction -Bohr pointed out the flaw in Einstein's reasoning: -For Einstein demonstration, one would have to know simultaneously both the barrier's initial position and any motion it might have had. -The uncertainty principle limits the accuracy with which both position and motion can be simultaneously known-Because of this, it is impossible to know which way the barrier moves. -With simple algebra, Bohr was able to show that this uncertainty would be large enough to foil Einstein's demonstration.

Week 2 Part 8: Neutron Activation Analysis, What's the Finding?

Bombarding a sample with neutrons to make some stable element (iridium, in our case) radioactive so that one can calculate its abundance by measuring the radiation level.

Week 9 Part 4: What's the difference between the classical and quantum probabilities? (shell-game example)

Classical probability: There is a physical pea under a shell, if someone peaked and saw the pea under the right-hand shell, it becomes certainty to that person, but to the operator of that game, IT IS STILL 50/50 CHANCE: -Even after the shell is lifted, I did not see the pea. Quantum probability: Collapse of wavefunctions -If someone happened to see the atom at a particular spot, that look would collapse the spread out wavefunction of the atom to be concentrated at that particular spot for all subsequent observers. -IT BECOMES 100% CERTAINTY FOR EVERYONE, even if I did not see it, the whole world would know even if they didn't see it. -The atom's wavefunction and the atom are the same thing

Week 9 Part 10: How are experiments 3, 4 and 5 explained using the collapse of the wavefunctions?

Collapse Of Wavefunctions: Experiment 3: Electrons are particles at production and detection (a form of measurement), but are interfering waves during flight (because there is no measurement/observation) Collapse Of Wavefunctions: Experiment 4: -In production and detection, they are particles but in between, because nobody was observing it, the electron was a wave -A single electron's wavefunction can interfere with itself during flight if it is not being observed/measured, because it is a wave -Its wavefunction continue to extend over space until it hits (measured) by the backstop. Collapse Of Wavefunctions: Experiment 5 -Once electrons are being observed/measured, the wavefunction collapses, it stops behaving as a wave and turns into a particle, no interference is observed on the backstop. -Collapse of the wavefunction is very powerful and is very consistent to explain everything throughout our series of thought experiments

Week 8 Part 10: What is Heisenberg's Uncertainty Principle? Explain using the constructive and destructive methods of waves Ask Patty

Constructive: the variation of wave amplitude that occurs when waves of the same or different frequency come together and the wave is increased Destructive: When crests and troughs interact, partially canceling all of the waves, creating composite waves with heights smaller than those of the original waves

Week 5 Part 28: Einstein light quanta hypothesis (What did Einstein Asked?)

Determined: Light quantum must have a threshold frequency so that hF is bigger than or equal to W to cause the electron to escape from the metal as long as the light's frequency is greater than F. Blue, not red, can do it. This completely explains all the logic of the experimental data on the photocentric effect

Week 11 Part 8: Summary Of Alice & Bob Experiment by EPR and Copenhagen

EPR -Physical reality: There is physical reality because once Alice measures, Bob's state is known without being disturbed -Locality: Impossible to communicate faster than the speed of light, there must be hidden variables to help change Bob's state Copenhagen Interpretation -No physical reality: There is no physical reality, Alice knows Bob's photon, but Bob doesn't until he measure himself (and disturbs the photon) -Nonlocality: Bob's state changes instantly, but no violation of the speed of light because there is no communication, you can't send an instantaneous greeting card this way and there are no hidden variables.

Week 10 Part 6: What's the debate at the 1927 Solvey Conference? How did Einstein challenge the Copenhagen Interpretation?

Einstein's first challenge -Send electrons toward a two-slit barrier one at a time. let the barrier be movable, say, on a light spring. -Consider the simplest case, an electron that landed in the central maximum of the interference pattern. -If that electron happened to come toward the bottom slit, it had to be deflected upward by the barrier. -In reaction, the electron would kick the barrier downward. And vice versa if the electron was on the top slit. -By measuring the movement of the barrier after each electron has passed, one could know through which slit it went. -Einstein's conclusion: Quantum theory was wrong in explaining the interference pattern by claiming each electron to be a wave passing through both slits.

Week 5 Part 29: Einstein light quanta hypothesis

Einstein's hypothesis: ● Light is a stream of discrete, compact, and indivisible photons each of energy ΔE = hf. ● A photon is the smallest amount of energy at a particular frequency; there is no such thingas a half photon. ● One photon is emitted/absorbed by one electron in an all-or-nothing way. -Einstein gave us a new interpretation of Planck's idea in the quantum property of light -Light quanta are not just some complex mechanism associated with emission of absorption in the thermal blackbody balls as Planck had thought. -Rather the quantum property is intrinsic to light itself and began to be called photons, which light is composed of.

Week 8 Part 4: What principle was followed by using a dimmer light? (hint, photoelectric effect)

Einstein's photoelectric effect

Week 5 Part 18: Experiment 1 Bullets Part 1

Experimental setup: -"What is the probability that a bullet which passes through the openings in the wall will arrive at the backstop ?" -"probability" means counting the number of bullets which arrive at the detector at a certain position. -Bullets are indestructible, always one identical lump or nothing on the backstop (discrete).Experimentation: 3 parts1 open, 2 closed1 closed, 2 open1 and 2 both open.Probability: P12= P1 + P2The probabilities just add together. The effect with both open is the sum of the effects with each open alone.We conclude: The bullets go through either opening 1 or opening 2. "no interference."

Week 6 Part 1: Experiment 2

Experimental setup: -We measure intensity instead of counting bullets. -The intensity of the wave can have any value (continuous). -We would not say that there was any "lumpiness" in the wave intensity.

Week 6 Part 2: Experiment 2

Experimentation: 3 parts -1 open, 2 closed -1 closed, 2 open -1 and 2 both open. -The intensity 1 over 12 when both are open is certainly not the sum of I over 1 and I over 2. -We say that there is "interference" of the two waves. -1 over 12 ≠ 1 over 1 + I over 2 -Constructive and destructive interference

Week 5 Part 19: Experiment 1 Bullets Part 2

Experimentation: 3 parts 1 open, 2 closed 1 closed, 2 open 1 and 2 both open. Probability: P12= P1 + P2 The probabilities just add together. The effect with both open is the sum of the effects with each open alone.

de Brogile's goal

Find a way to describe wavelength of particle

Week 6 Part 13: Experiment 3, the conundrum of electrons Part 3 (Conclusion)

For electrons,P12 ≠ P1+P2 -When electrons arrive at a double slit, they seem to interfere and we all make sure these are all single electrons at the time so these electrons are produce one at a time. -Backstop: Detector to make a noise. When an electron lands on the detector, you hear a click, so we make sure on the backstop, all we hear are a bunch of clicks. -Since the number that arrives at a particular point is not equal to the number that arrives through 1 plus the number that arrives through 2, as we would have concluded from Hypothesis A, undoubtedly we should conclude that Hypothesis A is false. -What we observe after is unexpected to us. We observe interference patterns/big bump on the backstop. -If we block one and open the other one and vice versa, we get two bumps if the bullet goes through either 1 or 2 -If we add them, we get a one round big bump on the backstop -As expected, bullets behave like particles -It is not true that the electrons go either through 1 or 2.

Week 2 Part 5: Who were the names of the scientists Luis and Walt enlisted as coworkers

Frank Asaro and Helen Michel

Week 5 Part 26: difference between frequency and intensity (Einstein light quanta hypothesis)

Frequency of light: strength of one kick (color of light) Intensity of light: number of kicks with the same strength (brightness of light) -The threshold is determined by the color (frequency) of light, a low energy photon can not overcome the threshold. -The dimmest of dim beams, a single photon, can still eject a single electron. Dim light simply means fewer kicks, doesn't mean the kick is weak.

Week 11 Part 12: Test of Bell's Theorem: If Bohr or Einstein is correct

If Bohr is Correct -If there is indeed a "spooky action in the distance", Bell's Theorem predicts that the two detectors will flash the same color with probability of 1/2 If Einstein is Correct -There must be hidden variables, a instruction set that governs each detector. The two detectors has the same color with probability of more than 5/9

Week 5 Part 33: Max Planck (Background)

In 1875 when young Max Planck announced his interest in physics, the chairman of his physics department of the University of Munich suggested he find something more exciting. "All the important discoveries have already been made." -The major still unexplained phenomenon was "thermal radiation (black body radiation)", the light given off by hot bodies. That became Planck's focus. -Max Planck struggled for a decade seeking to derive a theoretical formula that matched the experimental data without success -Out of frustration, he tried to work the problem backwards. Why not first try to just guess a formula that agrees with the data, and then with that presumably correct equation as a solid hint, try to develop the proper theoretical explanation. The formula fits data extremely well.

Week 5 Part 21: Photoelectric effect (Hertz)

In 1887, Heinrich Hertz discovered: ● if a polished metal surface is struck by light, electrons will pop out. ● Red (long wavelength, low frequency) won't do the trick; only green/blue/ultra violet (UV,high-frequency) will. ● The speed of electron flying out depends on color (frequency) ● For each metal, there is a minimum frequency (color) to pop out the electrons. (threshold)

Week 6 Part 5: Quantitative understanding of the size of an atom

In the late 1800s, what's inside an atom was still unknown, there was no testable hypotheses either. -As "classical physics" matured, atoms became an increasingly important research interest. But atoms are TOO SMALL to look at using a microscope. -J. J. Thomson (1856 - 1940), Nobel Physics 1906, discovered the electrons in 1897, the first subatomic particle. Made people realized that there is some structure within an atom -The Thomson Model: rice puddings (or plum pudding model) -If you can't examine an object with your eyes, how else might you find out about its size, shape, or composition? -One way is to toss little rocks at it and see how they bounce off.

Week 1 Part 1: Monkey & Gun: What does common sense tell you?

It is common sense that we should aim below the monkey.

Why Scientific Inquiry?

It is not about any subject in science, it is about how to think critically. It is about how to find truth.

Why does the size of energy radiant packets, involved in modern atomic theory, be proportional to the frequency?

It works

Week 2 Part 2: Characteristics Of Walt Alvarez's Rock

Lower section: White limestone Middle section: Half-inch layer of clay Upper section: Red limestone The rock was laid on the ocean floor 65 million years ago at the K/T Boundary 95% calcium carbonate from complicated seashells and 5% clay from continental error Walt wrongly concluded that the clay layer took 5,000 years to form

Who was the one who coined the term quantum mechanics?

Max Born

Light sometimes behaves like a wave, and other times, its a particle

Maxwell

"Anyone not shocked by quantum mechanics has not yet understood it"

Niels Bohr

Week 5 Part 15: The demonstration of the photoelectric effect experiment

Red: no electrons Green: slow speed electrons Blue/UV: high speed electrons Look at picture on your phone

How is "Martix Algebra" different from the algebra you learned in high school?

Regular algebra: A x B is the same as B x A Matrix algebra: A x B and B x A are not the same

Week 9 Part 16: How to figure out probability using counting (and without a formula)?: Understand how ALL probabilities are calculated in the examples (on the slides), please do not memorize

Possible outcomes of flipping a dice and coin simultaneously -12 possible outcomes: 1H, 2H, 3H, 4H, 5H, 6H, 1T, 2T, 3T, 4T, 5T, 6T Rolling a Die Twice and Sum it up: -Probability of 22: 1/6x1/6=1/36 -Probability of 13: 1/6x1/6=1/36 -Probability of 31: 1/6x1/6=1/36 -Probability of a sum of 4 means to get 22 or 13 or 31 Probability that the sum is four is 22 + 13 + 31= 1/6x1/6 + 1/6x1/6 + 1/6x1/6 = 1/12

Light determined to be a stream of particles

Quantum Theory is born

Week 5 Part 38: Light is determined to be a stream of particles

Quantum physics is born

Week 9 Part 12: How to figure out probability using counting (and without a formula)?: Understand how ALL probabilities are calculated in the examples (on the slides), please do not memorize

Rolling A Dice Once and Counting It More or Less -Roll dice one at a time -20 x 3 rolls= Roll the dice 60 times Number facing up: Every time, write it down: Roll 1: 6, Roll 2: 3, Roll 3: 4, etc (look at purple boxes in slide 2) -Total=60 different rolls/trials, all possible outcomes purple -1: 10 times, 2: 7 times, 3: 9 times, 4: 13 times, 5: 9 times, 6: 12 times=60 -Calculate = Probability = Successful outcomes/ possible outcomes: -Probability of getting 1: 10/60=1/6 -Single Roll: 6 outcomes -3x20 theoretical average is 10 -We now expand our trial to explain why 2=7, 3=9, etc -30x20 theoretical average is 100! Bigger sample size/trials=600/numbers are in yellow Probability of 1 now=approx. 99/600=16.5%, still 1/6 since 99 is close to 100. Every time the number can be slightly different, but they are very close, which is nature of statistics

Week 9 Part 13: How to figure out probability using counting (and without a formula)?: Understand how ALL probabilities are calculated in the examples (on the slides), please do not memorize

Rolling A Dice Once and Counting It More or Less Part 2 Difference between the two stamps of samples -1st one: 60 trials -2nd one: 600 trials -The more you increase the number of trials, you error is reduced -Ex:Smaller sample: 3/10 or Error is 30% -Ex: Larger sample: 13/100 or Error is 13% -We need to have enough samples. Sample size is very important. If you only do it 10 times, your number will be all over the place. -But the more samples you have, the closer your number will be to the theoretical number -First important probability rule: We need to have a big enough sample size in order to have a stable result. No formula, just counting

Week 9 Part 14: How to figure out probability using counting (and without a formula)?: Understand how ALL probabilities are calculated in the examples (on the slides), please do not memorize

Rolling A Dice Twice and Counting It More or Less Double Rolls: 36 outcomes Purple set of trials: smaller sample size Yellow set of trials: Larger set of sample size 18x20= 360, Theoretical average is 10 -Most important thing you want to do when you calculate probability is to construct all possible outcomes. If you roll a die twice, you have to get two numbers. What are the possible combinations of the two number? 6 possible combinations, 1/1, 1/2, 1/3, 1/4, 1/5, 1/6 -Ex: First roll 2, second one will change from 1/6 -Total: 6 sets, 36 outcomes -Red numbers: All possible outcomes -Bottom purple: First one is 52, second one is 55, third one is 42, etc, keep doing it many times, for a total of 360 times -Each roll: 20 trials so you need 18 rolls for 36 different outcomes because you need to make a round number. If each roll has 20, I need 18 more to make 360, so that ideally, for each pot, I have 36 pots here. Each pot on average should have 10 -Count all the numbers for each outcome. Ex: 1st roll is 1, 2nd roll is 1=13, keep counting for everything

Week 11 Part 11: Test of Bell's Theorem: Scenarios 1 and 2

Scenario 1 -If the two detectors have the same orientation, and both wheels stop at A, they always flash the same color. -A is in both observing windows in the blue circle Scenario 2 -Alice: A -Bob: B -If the detectors stop at different spots, they are not always the same (not always A and not always B). In this case, one of them is A and the other one is B. -If the two detectors have different orientation, they might or might not flash the same color. -Suppose Bob's wheel stops at B instead of A, the right photon has a probability of 1/2 of being vertical so Bob's light will flash red 1/2 (half) the time, and green 1/2 (half) the time -Regardless of orientation, the two detectors flash the same color with a probability of a half.

Week 11 Part 6: Understand the similarities and differences among the classical, semi-classical and quantum Alice and Bob thought experiments: Semi-classic

Semi-classical analogy: We know gloves (which were each put in separate boxes and sent to Alice's planet A and Bob's planet B) are physical reality, but we don't know which way they are going (it is completely random). -Alice's glove arrives first cause her planet is closer, and when she finds out her glove is right handed, she instantly knows Bob will get a left handed glove even though he hasn't received it yet. -But it is impossible too know which one Alice gets until she checks it. -EPR also argued that it was impossible that the right box, 20 million miles away from Alice's measurement, could have been mechanically disturbed by the measurement of the left box. (Locality)

Randomized Trials

Subjects are randomly selected into two groups :-Group 1: the control group (no intervention is provided) -Group 2: the experimental group (where the intervention occurs/is assessed) -You then compare the experimental group with the control group

Superposition of waves (20 waves) Superposition of waves (100 waves)

Superposition of waves (20 waves) -Each frame has one more wave with a different wavelength added to it. -20 waves with different wavelengths are added together, the peak, or the amplitude, becomes more concentrated in a small area with a very sharp peak at the center. Superposition of waves (100 waves) -You don't see waves cause everything is flat -But you still have a very sharp peak at the center within a small area. -Doesn't that describe a particle? With high concentration in one small area, and nothing else? -Significantly localized amplitude, almost point-like, or a particle -We see how the waves evolve into a particle -This answers the question: How do we use Schrodinger's wave idea to describe a particle?

Symbol Y (x, t) over 2 (square) Symbol Y (x, t) over 2 (square) = 0 Symbol Y (x, t) over 2 (square) is large Symbol Y (x, t) (wave function)

Symbol Y (x, t) over 2 (square) Probability of finding particle at position x at the time t Symbol Y (x, t) over 2 (square) = 0 The electron never turns up Symbol Y (x, t) over 2 (square) is large There is a large probability of finding an electron Symbol Y (x, t) (wave function) Represents the square root of a wave of probability

Week 8 Part 12: What is the only consistent way of explaining how electrons behave in the double slit experiment?

The Copenhagen Interpretation

Week 8 Part 8: What is the only consistent way of explaining how electrons behave in the double slit experiment?

The Copenhagen Interpretation

Week 8 Part 5: What's Heisenberg's major contribution to quantum physics? (Uncertainty principle and One man Paper)

The One Man Paper (Heisenberg) -On June 7, 1925, Heisenberg went to the island of Helgoland in the Black Sea to recover from a severe attack of hay fever. -Then at 3am one morning, Heisenberg got the bright idea and figured it all out with his newly formed "matrix agenda" -There he completed the calculation of his "matrix algebra" approach predicting the spectral lines. -Returning to Gottingen on June 19, 1925, Heisenberg composed his fundamental paper: "On A Quantum Theoretical Reinterpretation of Kinematic and Mechanical Relations". It was completed on July 9, 1925 and published in German that month. -In this paper, the starting point for a new quantum mechanics, Heisenberg announced as the leading philosophical principle of quantum mechanics that only observable quantities are allowed in the theoretical description of atoms. -Heisenberg reported his new results during visits shortly thereafter in Cambridge.

Week 6 Part 14: Review of Planck and Einstein

The early days of the quantum idea: -Max Planck: Radiation of energy was emitted not continuously, as seemed natural, but in little packets of radiant energy. -The size of the energy depends on the frequency: ΔE = hf -Albert Einstein: Light is also packets of energy, light is a particle, light quanta. -Frequency of light: strength of kicks Intensity of light: number of kicks

Week 5 Part 36: thermal equililbrium

The state of two or more objects or substances in thermal contact when they have reached a common temperature

Why do we not observe quantum phenomenon from our everyday objects?

There is no conflict with quantum physics.

Week 2 Part 13: How do scientists (Luis Alvarez etc.) announce their research findings?

Two ways: 1. Through scientific journals 2. Through scientific conferences

Week 6 Part 15: Receptions by the science community during the 1900s of Einstein and Planck's early quantum ideas

Very few took the idea seriously. There is something more disturbing at that time...

Week 5 Part 20: Experiment 1 Bullets Part 3

We conclude: The bullets go through either opening 1 or opening 2. "no interference."

Week 6 Part 3: Experiment 2

We conclude: there is interference

Week 2 Part 12: What is a referee?

When a peer reviews your work and determines whether or not it should be published

Week 4 Part 25: destructive wave interference

When crests and troughs interact, partially canceling all of the waves, creating composite waves with heights smaller than those of the original waves

Dark spot in experiment 4

Where fewer electrons will land

Week 5 Part 25: Could fields be measurable despite being invisible?

Yes

Black objects

absorb all colors

Basic properties of a wave

amplitude (how big it is), wavelength, frequency, and speed

Week 4 Part 7: Refraction

bending of light by transparent materials such as glass and plastic

Week 4 Part 23: Wave interference patterns

collision of two or more wave systems, constructive and destructive

Week 5 Part 2: wave velocity

frequency x wavelength

How is momentum measured?

mass x speed

Dot in thought experiments are...

particles

"c"

speed of light, and one of the most important pieces of the puzzle that constitutes the whole physical media universe

The Cretaceous and Tertiary (Paleogene) periods

the K/T boundary when the dinosaurs and most other forms of life on earth abruptly became extinct 65 millions years ago.

Week 2 Part 3: The Cretaceous and Tertiary (Paleogene) periods

the K/T boundary when the dinosaurs and most other forms of life on earth abruptly became extinct 65 millions years ago.

Week 5 Part 1: Amplitude

the height of a wave's crest above a calm sea surface

Amplitude

the height of a wave's crest above a calm sea surface -The technical expression for the probability is the "absolute square of the wave function". -It is the probability of finding the object in that region.