Great Ideas Final
frequency
# of vibrations that occur in 1 unit of time - 1/period - measured in hertz
photoelectric effect (Einstein)
- assumes that light is not continuous and instead made up of invisible particles called photon - light isn't a wave - because otherwise this occurrence wouldn't happen, it was the frequency of the electromagnetic wave that determined the energy transferred not the intensity
throughout time (steps for next few cards)
- big bang occurs -exotic law of physics - era dominated by the development of quarks/ anti quarks - the grand unified theory develops, matter wins over anti matter (dont know why)
relativity of length 2
- measured lengths cannot be equal - a MOVING OBJECT SHRINKS (but only in the direction of motion) - the length of an object decreases the faster it moves relative to the observer (length contradiction)
if waves behave like particles, can particles behave like waves?
- when individual photons are subject to the double slit experiment, one at a time we see an interference pattern - if light were only particles, this would suggest that particles can interfere with themselves - effect is specifically related to the probability of a particles motion
example of relativity
-person standing still throws a ball forward, to that person the ball appears to move away at some velocity away from him - to a person traveling in the same direction at the same velocity as the moving ball, even appears as the ball is standing still and the thrower is moving backwards - person moving is in a different reference frame than the person standing still
cat dead or alive 2 (LR)
1. cat is both dead and alive, while being neither at the same time 2. after opening the box, probability is collapsed into cat-life or cat-death depending on the measurement of the coin flip 3. able to perfectly measure the state of the cat, probability collapses into zero uncertainty
important factors to this research
1. how much matter is actually in the universe "dark matter" 2. other kind of energy gently varying the expansion of the universe "dark energy" - this may lead to a "big rip" where the expansion of universe speeds up and rips itself apart
death of the universe
3 different situations in which the universe can eventually end up
Leptons
Electrons are their own quark, and belong to a class of particles called Leptons
mass and energy
MASS AND ENERGY ARE THE SAME THING - increasing velocity increases mass and energy - energy and mass are directly related - mass is actually the physical representation of potential energy
positrons
Positrons behave as electrons moving backward in time • Same particle o As time moves further, we see the annihilation of electrons and positrons into high energy photons
relative momentum 2
THE MASS OF AN OBJECT INCREASES AS IT MOVES FASTER - no particles can be accelerated to the speed of light - mass approaches infinity as v approaches c ... it would take an infinite force to accelerate an infinite mass
the quantum zeno paradox
Take an unstable system (such as an excited electron in an atom) and subject it to repeated measurement, collapsing the wave function of time
properties of waves
Waves transmit energy and information from one place to another without any material object A wave can represent any repeating motion "wave particle duality" basis of modern day physics
is the cat dead or alive (LR)
after the coin falls, probability of the cat being alive is 50-50 - before we open the box to measure what happened (collapse the probability fuction) we cant assume the cat to be either dead or alive
Beginning of the universe
all of the universe was confined into 1 tiny point of infinite density which exploded sending the universe expanding in all different directions - as the universe cooled, particles became attracted to each other and formed all the objects currently in existence - universe is still expanding
gravitational fields
arise from the presence of some mass, so mass must warp space-time to form the curve surface - mass acts as weight, and particles that have enough energy can escape the bowl, but all others will fall to earth -the more massive an object is, the more it will curve the space-time around it and fewer objects will be able to escape
the doppler effect 2
as the source moves away from the observer, the distance between the waves increases -frequency of sound will decrease
cloud of probability
atoms look like a mess; the consist of a nucleus surrounded by a "cloud of probability" which provides the possible positions and energies of the electrons because we can't know exactly where they are
how atoms look
atoms look nothing like the bohr model, but its useful for purposes of demonstration -quantum physics showed us that the position and motion of everything is based on probability
constructive interference
both waves have a positive amplitude -sum of the two waves is greater than either of individual waves
general relativity
covers non-inertial (accelerating) reference frames
nuclear explosion from the sun
creates hydrogen and a bunch of energy - this is the energy the sun burns - this is self perpetuating because the gravity is causing it to constantly pull itself into the center - gravity pulls in and the explosion pushes outward which holds the sun in stable position
special theory of relativity
deals with inertial reference frames
the doppler effect 1
describes the change in frequency as a sound emitting object moves with respect to an observer - the waves are closer together as they approach the observer - wavelength is smaller - velocity of sound is not changing - frequency that observer hears, increases to compensate for decrease in wavelength
electromagnetic spectrum
different frequencies (or wavelengths) have different appearances - including visible light - most frequencies are invisible to humans
light as a probability wave
diffraction pattern of maxima and minima will appear on the screen - although we cannot tell where a photon will strike the screen, we see that the relative probability of a photon striking the screen at a certain point is proportional to the intensity of light at that point
Amplitude
distance from midline to the top of the crest - maximum displacement from equilibrium position - measures in units of displacement (meters)
wavelength
distance required to complete vibration - distance between 2 crests or 2 troughs - measured in units of length
elements
elements (types of atoms) are displayed on the periodic table where the columns and rows provide info on elements with similar properties
electrons changing energy levels
emits or absorbs a single photon, the energy of which has to match the energy difference between the atomic energy levels
cosmic background radiation
energy is form of light (radiation) and is known as the cosmic background of radiation - radiation exists everywhere in space supporting the notion that it originates at some central point and moves outward
beginning 2
everything in the universe is moving away from everything else - speed at which galaxies are moving from us is directly proportional to their distance from us, implying they all started from the same place - if rate of expansion is constant, the age of the universe is 13.7*10^9 years old
light as a probability wave 2
for every point in a light wave, we can ascribe a probability that a photon can be detected at that point - this probability will look exactly like our diffraction pattern - we can describe the motions and interactions of light as a probability wave
relativistic energy
force and kinetic energy are related to the momentum of a system, thus will also behave relativistically - rest energy of a particle, similar to the potential energy of an object - Total energy E of a particle must be conserved
Heisenberg uncertainty principle (long response)
found that the product of all uncertainties of position and momentum could not exceed a specific amount - uncertainty is the opposite of accuracy - if uncertainty is zero, accuracy is perfect - if uncertainty of either property is zero, then the other has infinite uncertainty
probabilistic interpretation
helps to explain what will happen if only one photon passes through the slits - if only 1 photon is directed at the slits, diffraction pattern will still occur, contrary to descriptions of interference - because no matter how many photons are incident on the slits, the probability of them striking a certain point doesnt change
Nuclear fusion
how the sun and other stars burn - huge gravitational force can fuse small atoms together and make larger atoms, and the energy given off in the form of light and heat - how all the matter in the universe was created
mass and energy 2 (E=mc2)
if a particle has mass it also has energy -Manhattan project world war 2 atomic bomb - process for releasing nuclear energy relies on changing the mass of particles(atoms) - most large atoms are not very stable, they can decay into smaller atoms and have different mass after decay - mass that was lost was being turned into energy
cover slits
if we cover one of the slits, the pattern of the photon intensity on screen is destroyed - resulting pattern resembles a single peak of probability - without the second opening, probability of the photons final destination is not affected by interference through 2nd slit - photons are smart - they act differently based on the probability of different situations they may encounter
nuclear fission
in the process of triggering rapid decay of a huge # of atoms which all release their mass at the same time
probabilistic interpretation 2
it doesnt require 2 photons to interfere to create a diffraction pattern - imagine photon interfering with itself as it passes through the slits - the photon effectively passes through both slits at once, interfering with itself on the other side
basis of theory
its a principle of equivalence - state that there is no difference between a uniformly accelerating reference frame and one which is in a uniform gravitational field
light and the theory
light can be deflected by a gravitational field - light does travel the shortest path through space, which can only occur if space itself is curved not flat
matter (3)
matter and radiation energy begin to become separate identities - matter begins to cluster together forming the extra-stellar objects such as stars, quasars, and proto-galaxies. larger starts to begin to produce heavier elements
matter waves 2
matter waves can be treated in the same probabilistic manner as photons - MOTION OF PARTICLES IS SIMPLY A PROBABILITY - shown by sending electrons one at a time through a double slit apparatus
doppler effect measurement
measure the motion of objects reflecting sound waves off to the object - if reflected waves are high in frequency, the object is moving toward the observer - how much frequency changes tells us how fast it is traveling
spectroscopy
measures the photons that are emitted by atoms, different colors of light implies photons of different energys
Realistic viewpoint
measuring the property that the particle already had • Implies that quantum physics is an incomplete theory • Still cant determine the properties with all of our info so there must be more
light behaves like a wave
moves through space as a wave and it exhibits diffraction and interference effects - there is no way that a wave can produce the results from the photoelectric experiment, (a light would have to focus all of its energy on only one particle)
throughtime 4
new galaxies continue to form, along with solar systems such as our own - elemental atoms begin to bond and link together in order to form more complex systems (such as molecules of life forms) - NOW
many worlds interpretation
o Every time a quantum particle is forced to collapse its wave function by measurement, it actually collapses into all of the possibilities instead of just one. • If a particle is equally probable to be in a State A or B when we measure it, the wave function collapses into both state A and B o We only observe wave function collapse into one of the states because the other collapse is only observed in a parallel universe
Energy time uncertainty 2
o In terms of tunneling, this implies that the particle can borrow enough energy to overcome the barrier, as long as it pays the energy back in an appropriately small time o The longer the time needed, the less likely that the energy will change • Spontaneous change of energy has been observed in electron transitions within atoms, using spectroscopy
tunneling 2
o The wave moves around the particles o For each particle you add, you get harmonics of the wave o As we lower the sides of the box, the wave gets wider • But when the wave widens, there becomes a probability that the particle isn't in the box But this is true, particles can escape walls • This is called tunneling o Tunneling- the probability that the particle exists out the barrier
black holes
objects of enormous mass that have collapsed into a zero volume - create a very deep bowl whose sides are practically vertical - not even light has enough energy to escape this bowl
observer on a cart with mirror example
observer will see the light move in the same manner as if they were standing still another observer watches cart go by - they will see the light take different path than observer on the cart - observer 2 sees the light as moving to the right and up and down, to them light travels at a greater difference than it does for observer 1 - the light is traveling at the same speed for both observers
Interference
occurs when multiple waves overlap each other, resulting in a different final product
Diffraction
occurs when waves are forced to move around objects in their path
curved surface
on a curved surface, the shortest distance between 2 points will be a curve, making light move in a curve path - these curves in space only appear in an accelerating reference frame - same as a gravitational field
the relativity of time
people measure events differently based on their position, implying space and time are all related - speed of light is constant in all reference frames ******
agnostic viewpoint
philosophical or metaphysical and irrelevant to understanding the quantum world
Hydrogen
primary element in the universe - first element created in the world and all that exist are remnants of the first few minutes of the creation of the universe
standard model of particles
provides all of the particles discovered and theorized that make up everything in the universe - most complete theory of matter and energy in the universe, all interactions modeled on the exchange of particles
Schroedingers cat (long response)
put a cat in a sealed box with poison gas - hammer is attached to a falling coin - is coin lands heads, the hammer will smash the vial and kill the cat, if tails nothing will happen and cat will live
matter waves
quantum mechanical description of particles such as protons and electrons
matter waves
relationships between the wave and particle nature of light - relation wavelength and momentum in terms of the de broglie wavelength - the wave particle duality extends beyond light to cover all matter - even things we obviously see as particles will exhibit wave behavior, specifically behaving like matter waves - De Brogile wavelength of a matter wave depends solely on the momentum of a particle
matter waves 3
resulting pattern on screen was identical to that of light passing through a double slit apparatus - electrons passing through the slits interfered with themselves to produce diffraction patterns - probabilistic nature of particles applies to everything - very massive objects (us) exhibit such small wave behavior that we don't notice
maxwells equations about light
shine light onto a metal plate - electrons are ejected from metal which can be detected as current - this was explainable, the electric field vector of an electromagnetic wave can interact with the electrons giving them kinetic energy
mechanical waves
some type of physical medium transmits waves - water, sound, seismic
sun 2
sun will keep getting larger as it keeps burning bigger and bigger atoms as it makes fuel - this will happen until gravity cant pull these particles anymore and that is why the sun will die
orthodox viewpoint
the act of measuring created a property which we measure. The particle neither had no didn't have the property until the measurement • Something peculiar about the measurement process • Collapsing the wave function destroys some of the probabilistic nature we know exists
velocity
the distance a crest (or trough) travels in time
mapping electron levels
the electron levels of an atom can be mapped by measuring the photons which are given off by electrons which move from level to level
proof of photons
the fact that light emitted from electrons only occured at specific energies, proves the existence of photons and quantum mechanics
3.
the force of gravity and the energy supplied by the big bang are perfectly matched - expansion will slow down and approach zero, but the universe will never contact and we dont know what will happen - evidence suggests that the universe is very close the 3rd possibility
Relativity
the measure of event which occur in space and time - concerned with where and when events happen and how the events are separated in space and time - events appear from different reference frames
wormhole
the possibility of an object having enough mass to curve space time around on itself, allowing object to travel to different parts of the universe without have to actually move very far or fast
combination of quark (2)
the quarks then combine and form protons, neutrons, and electrons - from the protons and electrons come principle elements such as hydrogen, helium, lithium, and deuterim
electron transition
there is no "in-between" for electron transition, it is either a single complete transition or none at all - if their were an "in-between" you would see a gradual spectrum of colors for every transition
1.
there is not enough mass in the universe for the force of gravity to overcome the energy supplied initially by the big bang - universe will just continue to expand
2.
there is plenty of mass in the universe and the force of gravity will overcome the expansion of the universe - the expansion of the universe will slow down and reverse, with the end coming in a "big crunch" (100 billion years)
Heisenberg uncertainty principle 2 (long response)
this effect occurs for any particle which can be treated as a wave and occurs in most dimensions - this is not a problem of measurement - it is inherently associated with the principles of physics themselves
time is not absolute
time dilation equation- tells us that an object traveling at velocity v experiences different time interval than one standing still - time slows down the faster you travel - things that move quickly live longer
period
time required to complete 1 vibration
the relativity of length
to measure the length of something moving at a high velocity, both end points need to be noted simultaneously in reference frame length- relative concept - because of time dilution, the relative times each observer notes the same event cannot be equal
relative momentum
total momentum of objects (mass x velocity) involved in a collision would be conserved by all observers in any reference frame - momentum of an object increases as the particle moves faster relative to an observer (v increase)
light behaves like a particle
wave/ particle duality is one of the strangest effects that can be attributed to quantum mechanics
Oscillation
waves are defined as vibration or wiggle that repeats in time or space whatever does the wiggling determines the type of wave
destructive interference
waves cancel out "in phase" and "out phase"
electromagnetic wave
waves in electric and magnetic fields that don't require a medium - travel at the speed of light - radio waves, light, microwaves, x-rays
transverse waves
when the motion/amplitude is at right angles to the direction of propagation (where it is created) - string vibrating, water wave, electromagnetic wave
longitudinal waves
when the motion/amplitude is parallel to the direction of propagation (where it is created)
sun
works on the basis of nuclear fusion - sun has a huge force due to gravity associated with it - pulls particles towards its center - it pulls particles with so much energy that they are rammed together and fused creating a nuclear explosion
ultimate heat death
would occur around 1 trillion years from now ( another possibility if the universe lived that long)
tunneling
• A particle has a total mechanical energy E which is constant, but the potential energy U(x) is a function of position and can change o As long as E is greater than U at the same position, the particle can move freely • Finding the probability wave from schredingers equation in three different regions (left, right, and inside barrier) we find definite probability that our electron will pass (tunnel) through the barrier
probabilistic paradoxes
• A wave function describing a particles properties does not uniquely determine the outcome of a measurement of those properties, it provides a probability of all of the possible results
Energy time uncertainty
• Another way to look at tunneling, in terms of momentum and position • Quantum particles can spontaneously change its energy by a small amount for a short period of time, as long as the product of these changes doesn't violate our inequality
Energy time uncertainty 3
• Particles can be created out of nothing as long as they only exist for a short time • When matter and anitmater collide, they annihilate each other, producing a high energy photon o Light doesn't "see" time, there fore we can reverse the arrows of the photons without affecting them
