Physics of Human Affairs UARK

Possible Shapes of galaxies

Closed - curved in on itself Parallel lines intersect Flat - no overall curvature Parallel lines remain parallel Open - saddle shaped Parallel lines diverge

Newtonian Reality

Energy Mass Time No speed limit

Newton

Energy conservation Force at a distance Given enough information, everything can be predicted Separate parts of universe for independent study

Quantum

Energy conservation Force at a distance Single experiments are not predictable Measurement affects answer. Everything is connected

Cosmology

How the universe works and how it is changing Predict how it started

Equivalence Principle

No experiment performed inside a closed room can tell you whether you are at rest in the presence of gravity or accelerating in the absence of gravity.

Recap: Galilean Relativity

No speed limit Based on Newton's Laws, make assumptions about the nature of Space Time Not quite right; problems at High speed Large distances Other problems at small distances - not due to relativity

Thought Experiment; Law of Motion

Velma and Mortimer each have 1 kg object Velma is still traveling in her fast rocket Mortimer applies a 1 N force to both objects Mort's object → a = 1 m/s2 (a = F/m) Velma's object; 2 possibilities Galilean: a=1m/s2 Einstein: a<1m/s2 ;length is contracted, time is dilated For Mort, Velma's object seems to have more inertia (inertia - body's resistance to acceleration) For Mort, Velma's object has more mass Mass is relative At 0.7c 1 kg mass would act like a 1.4 kg mass

Light Clock on Rocket

Velma sees light travel 300,000 km in one second Constant lightspeed means Mort sees Velma's light travel at c distance is larger than 300,000 km; takes longer to travel Mort's clock counts more than one second between Velma's ticks Velma's clock is slow according to Mort

Rocket Observing Light Clock

Velma watching Mort's clock Sees light beam of his clock travel more than 300,000 km Velma sees Mort's clock running slow

Thought Experiment: Mother and Child

You at 5 years, mom at 30 Mom goes to Vega, 26 light years away, stays for 3 years and returns Light year: 9.46 x 1012 km Travels at 0.999c; time dilation factor of 22.4 Mom gone 26+26+3=55 years Travel time for mom, 52/22.4 = 2.3 years Mom only ages 5.3 years (2.3 + 3 years) You age 55 years You are older than mom when she returns

general relativity

-large distance -large mass

2) You are a passenger in a moving car, and you drop a coin from your right hand, holding your left hand directly below the point of release. If the car is moving at unchanging velocity, the coin will come down A) in your left hand. B) in front of your left hand. C) behind your left hand. D) to the side of your left hand

A) in your left hand.

1) Velma is in a train moving north at 20 m/s. She throws a stone toward the rear of the train, at 5 m/s relative to herself. Mort, standing beside the tracks, sees the stone move A) north at 15 m/s. B) south at 25 m/s. C) north at 20 m/s. D) north at 25 m/s. E) south at 15 m/s.

A) north at 15 m/s.

6) We proved, using Einstein's two basic principles, that if Velma is moving past Mort then Mort should observe Velma's clock to go slow. This behavior of Velma's clock occurs because, as observed by Mort, A) the light beam in her light-clock travels further than 300,000 km during one of Velma's ticks. B) the light beam in her light-clock travels less than 300,000 km during one of Velma's ticks. C) Velma's light-clock shortens along its direction of motion. D) the light beam in Velma's light-clock travels at faster than the normal lightspeed. E) the light beam in Velma's light-clock travels at slower than the normal lightspeed.

A) the light beam in her light-clock travels further than 300,000 km during one of Velma's ticks.

32) One line of evidence supporting the big bang theory is A) the observed abundance of very light elements in our galaxy is just what is predicted by the big bang theory. B) the nuclear fission products observed in our galaxy are just what is predicted by the big bang theory. C) neutron stars have just the masses and frequencies of rotation that are predicted by the big bang theory. D) the observed abundance of very heavy elements in our galaxy is just what is predicted by the big bang theory. E) the density of galaxies observed in the universe is just what is predicted by the big bang theory

A) the observed abundance of very light elements in our galaxy is just what is predicted by the big bang theory.

In the preceding question, the velocity of the ball relative to Mort, who is standing beside the tracks, is: A. 50 m/s eastward B. 50 m/s westward C. 20 m/s eastward D. 20 m/s westward E. 70 m/s eastward F. 70 m/s westward

A. 50 m/s eastward

Velma flies past Mort in her rocket at 0.8 c. Velma is holding 10 kg book. Mort measures the mass of the book to be A. Greater than 10 kg B. Less than 10 kg C. 10 kg D. Impossible to know.

A. Greater than 10 kg

We proved, using Einstein's two basic principles, that if Velma is moving past Mort then Mort should observe Velma's clock to go slow. This behavior of Velma's clock occurs because, as observed by Mort, A. the light beam in her light-clock travels further than 300,000 km during one of Velma's ticks. B. the light beam in her light-clock travels less than 300,000 km during one of Velma's ticks. C. Velma's light-clock shortens along its direction of motion. D. the light beam in Velma's light-clock travels at faster than the normal lightspeed. E. the light beam in Velma's light-clock travels at slower than the normal lightspeed.

A. the light beam in her light-clock travels further than 300,000 km during one of Velma's ticks.

gENERAL THEORY OF RELATIVITY

Accelerating reference frames Earth (accelerating?)

7) Is it possible, according to Einstein's relativity, for a child to be biologically older than his or her parents? A) Yes, if the child goes on a long and fast trip and returns to Earth. B) Yes, if the parents go on a long and fast trip and return to Earth. C) No, because it is not possible to actually move backward through time. D) No, because the principles of relativity don't have anything to do with actual biological aging. E) No, because the "relativity of time" does not allow the actual order of events in time to be switched around

B) Yes, if the parents go on a long and fast trip and return to Earth.

23) According to the principle of equivalence, gravity is equivalent to A) energy. B) acceleration. C) velocity. D) net force. E) the state of free-fall.

B) acceleration.

21) Velma passes Mort at a high speed. Velma and Mort each have identical light-clocks. Mort and Velma both observe both clocks to "tick" simultaneously at 12 noon on both clocks. Mort observes that Velma's next tick occurs A) only after the second drink. B) after his own clock ticks. C) at the same time as the tick on his clock. D) before or after or at the same time as his own tick, depending on Velma's precise speed. E) before his own clock ticks.

B) after his own clock ticks.

25) Galaxies seem to be made mostly of dark matter. One type of evidence for this comes from observations of the A) energy emitted by distant quasars, which is far larger than can be explained by the visible matter in the quasars. B) gravitational bending of light from distant galaxies as it passes other galaxies on its way to Earth. C) redshift in the light from the explosions of distant supernovas. D) redshift in the light from the earliest galaxies in the universe. E) force of gravity acting on laboratory objects.

B) gravitational bending of light from distant galaxies as it passes other galaxies on its way to Earth.

13) One phenomenon that supports the wave theory of radiation is A) the transference of energy by a light beam. B) interference effects with light. C) the tiny flashes when an electron beam strikes a screen. D) the tiny flashes when a light beam strikes a screen. E) None of the above.

B) interference effects with light.

29) If a microscopic particle's uncertainty in velocity is reduced, A) its uncertainty in position must decrease enough to satisfy the uncertainty principle. B) its uncertainty in position must increase enough to satisfy the uncertainty principle. C) its uncertainty in position must remain unchanged.

B) its uncertainty in position must increase enough to satisfy the uncertainty principle.

16) In the context of the double-slit experiment, quantum uncertainty refers to A) the fact that each interaction with the screen occurs over a broad area of the screen. B) our inability to precisely predict the point at which a spread-out matter field or EM field will interact with the screen. C) the fact that the electron beam or light beam goes through both slits rather than only one. D) the fact that the particles of matter or radiation are instantaneously replaced by a spread-out matter field or EM field when the particles impact the screen. E) the fact that the entire matter field or EM field instantaneously collapses to the single interaction point when the field interacts with the screen.

B) our inability to precisely predict the point at which a spread-out matter field or EM field will interact with the screen.

3) Mort stands on Earth. Velma moves away from him in a rocket, at 299,000 km/s (1000 km/s slower than lightspeed). Mort sends a laser beam toward Velma. As the tip of the beam passes her rocket, Velma observes that A) the laser beam moves past her at just 1000 km/s. B) the laser beam moves past her at 300,000 km/s. C) Both of the above. D) the laser beam never catches up with her. E) Mort has turned into a giant frog.

B) the laser beam moves past her at 300,000 km/s.

12) Which of the following colors has the most energy per photon? A) yellow B) violet C) red D) all the same E) The answer depends on the intensity of the light.

B) violet

Velma moves away from Mort at 0.75c. She turns on 2 lasers, one pointed forward and the other pointed backward. According to Galilean relativity, how fast should the forward and backward beams move, as observed by Mort? A. 0.25c and 1.75c B. 1.75c and 0.25c C. 0.25c and 0.75c D. 0.75c and 0.25c E. c and c

B. 1.75c and 0.25c

If you drop a coin in a car that is slowing down, where will the coin land? A. Straight down B. Ahead of you C. Behind you

B. Ahead of you

The gold nuclei in the universe were A. Created in the big bang B. All created sometime after the big bang C. Created partly during the big bang, and partly after

B. All created sometime after the big bang

Since acceleration can mimic the effects of gravity, acceleration should be able to cancel gravity. Thus a person could experience weightlessness by: A. Blasting off from Earth at 1 g B. Falling from a high place (diving board, skydiving) C. Orbiting Earth D. Standing on the surface of the moon

B. Falling from a high place (diving board, skydiving) C. Orbiting Earth

If you drop a coin inside a car that is turning right, where will the coin land? A. Straight down B. To the left C. To the right D. Behind

B. To the left

Galaxies seem to be made mostly of dark matter. One type of evidence for this comes from observations of the A. energy emitted by distant quasars, which is far larger than can be explained by the visible matter in the quasars. B. gravitational bending of light from distant galaxies as it passes other galaxies on its way to Earth. C. redshift in the light from the explosions of distant supernovas. D. redshift in the light from the earliest galaxies in the universe. E. force of gravity acting on laboratory objects.

B. gravitational bending of light from distant galaxies as it passes other galaxies on its way to Earth.

In the context of the double-slit experiment, quantum uncertainty refers to A. the fact that each interaction with the screen occurs over a broad area of the screen. B. our inability to precisely predict the point at which a spread-out matter field or EM field will interact with the screen. C. the fact that the electron beam or light beam goes through both slits rather than only one. D. the fact that the particles of matter or radiation are instantaneously replaced by a spread-out matter field or EM field when the particles impact the screen. E. the fact that the entire matter field or EM field instantaneously collapses to the single interaction point when the field interacts with the screen.

B. our inability to precisely predict the point at which a spread-out matter field or EM field will interact with the screen.

According to the theory of relativity, iseverything relative? A) No, velocity is not relative. B) No, time and space are not relative. C) No, lightspeed is not relative. D) Yes. E) No, mass is not relative.

C) No, lightspeed is not relative.

18) Which of the following is a feature of quantum physics but not a feature of Newtonian physics? A) Force at a distance: Objects can exert forces on other objects that are some distance away, across empty space. B) The principle of conservation of energy. C) The observation process must be included as part of the theory. D) Determinism: The future is entirely determined by the present. E) All of the above.

C) The observation process must be included as part of the theory.

A particle of light is called A) a neutron. B) a quark. C) a photon. D) a proton.

C) a photon.

11) During the double-slit experiment with light, the region between the slits and the screen contains A) photons. B) a matter field. C) an electromagnetic field. D) electrons. E) None of the above

C) an electromagnetic field.

Einstein and Energy According to Einstein's E=mc2 and the "field view of reality," A. an atom's mass arises from the energy of its own fields. B. atoms are entirely empty space--containing only fields. C. Both of the above. D. atoms are mostly empty space, and consist of very tiny indestructible material particles that are attached to the atom by means of electromagnetic and other fields.

C. Both of the above. D is "before Einstein"

The electron microscope is based on the use of A. high-frequency sound waves. B. mesons. C. matter waves. D. electromagnetic waves. E. X-rays.

C. matter waves.

Einstein's Special Relativity

COMBINES TWO PRINCIPLES - Principle of Relativity - all physical laws are the same in all non-accelerating reference frames Principle of Constancy of Light Speed - speed of light (lightspeed) is the same in all nonaccelerating reference frame (Both principles require that the reference frame of the observer is not accelerating)

Constancy of Light Speed

Constancy of Light Speed The speed of light (and other electromagnetic radiation) in empty space is the same for all non-accelerated observers, regardless of the motion of the light source or of the observer.

Schroedinger equation

Correctly described electron motion Applied to electrons in atoms, predictions agree with observations

Special Relativity

Cosmic speed limit

The graph above, which we discussed in class, shows the relativity of time, space, and mass [you will need to figure out which graph goes with which effect]. As measured by Velma, her spaceship has a mass of 10,000 kg and a length of 100 m. She moves at 70% of lightspeed relative to Mort. According to Mort's measurements, the mass and the length of her spaceship are A) 7000 kg and 70 m. B) 7000 kg and 140 m. C) 14,000 kg and 140 m. D) 14,000 kg and 70 m. E) This question cannot be answered without knowing which observer is really at rest.

D) 14,000 kg and 70 m.

5) Velma, who is carrying a "light clock," passes Mort at a high speed. Velma observes that, during one tick of her own light clock, the light beam on her clock travels A) further than 300,000 km. B) less than 300,000 km. C) a distance of one light year. D) 300,000 km. E) no distance at all.

D) 300,000 km.

9) What feature of Einstein's theory of relativity is demonstrated by the phenomenon of matter-antimatter annihilation? A) the relativity of time B) the constancy of lightspeed C) the relativity of mass D) E = mc2 E) that too much television will give you gas pains and make you froth at the mouth

D) E = mc2

24) Which chemical elements were created during the first few minutes of the "big bang" that started our universe? A) All 92 of the naturally-occurring chemical elements. B) Only the elements through iron in the periodic table, i.e., only elements 1 through 26. C) Only the heaviest elements, having atomic numbers higher than that of lead. D) Only the first three elements: hydrogen, helium, and lithium. E) No elements were produced during the big bang--all the normal chemical elements were produced much later.

D) Only the first three elements: hydrogen, helium, and lithium.

31) What happens in the double-slit experiment with electrons if we place an electron detector just behind one of the slits? A) This provides no information concerning which slit each electron comes through, and has no effect on the pattern formed on the screen. B) We can then predict the precise point at which the electron will strike the screen. C) This tells us which slit each electron comes through, and has no effect on the pattern formed on the screen. D) This tells us which slit each electron comes through, but it also changes the pattern formed on the screen. E) This provides no information concerning which slit each electron comes through, but it does change the pattern formed on the screen.

D) This tells us which slit each electron comes through, but it also changes the pattern formed on the screen.

27) A photon is A) an electron that has been ejected from a metal surface by electromagnetic radiation. B) a high-energy electromagnetic wave. C) the "anti-particle" to the electron. D) a particle-like quantum of radiation. E) one of the two types of nuclear particles.

D) a particle-like quantum of radiation.

20) When an atom undergoes a "quantum jump" into a lower-energy state, the atom A) absorbs a photon. B) emits an electron. C) absorbs an electron. D) emits a photon. E) None of the above

D) emits a photon.

Velma passes Mort at a high speed. Each holds a meter stick, oriented parallel to the direction of relative motion. Mort observes that A) his meter stick is longer than 1 m, and Velma's meter stick is 1 m long. B) his meter stick and Velma's meter stick are both shorter than 1 m. C) his meter stick is 1 m long, and Velma's meter stick is longer than 1 m. D) his meter stick is 1 m long, and Velma's meter stick is less than 1 m long. E) his meter stick and Velma's meter stick are both 1 m long

D) his meter stick is 1 m long, and Velma's meter stick is less than 1 m long.

19) Referring to the figure above, the photons of highest energy are produced by A) quantum jumps from state 2 to state 1. B) state 1. C) the ground state. D) quantum jumps from state 4 to state 1. E) Impossible to determine without further information

D) quantum jumps from state 4 to state 1.

Velma's normal ball-throwing speed is 20 m/s. She is in a train moving eastward at 70 m/s and throws a ball toward the rear of the train. The velocity of the ball relative to Velma is: A. 50 m/s eastward B. 50 m/s westward C. 20 m/s eastward D. 20 m/s westward E. 70 m/s eastward F. 70 m/s westward

D. 20 m/s westward

Velma flies past Mort in her rocket at 0.8 c. Mort sees Velma's A. Clock and pulse faster than Mort's B. Clock faster but pulse slower than Mort's C. Clock slower but pulse faster than Mort's D. Clock and pulse slower than Mort's

D. Clock and pulse slower than Mort's

Which chemical elements were created during the first few minutes of the "big bang" that started our universe? A. All 92 of the naturally-occurring chemical elements. B. Only the elements through iron in the periodic table, i.e., only elements 1 through 26. C. Only the heaviest elements, having atomic numbers higher than that of lead. D. Only the first three elements: hydrogen, helium, and lithium. E. No elements were produced during the big bang--all the normal chemical elements were produced much later.

D. Only the first three elements: hydrogen, helium, and lithium.

Velma flies past Mort in her rocket at 0.8 c lengthwise over Mort's garden. Velma sees Mort's garden's A. Width increase and length decrease B. Width decrease and length remain the same C. Width stay the same and length increase D. Width stay the same and length decrease

D. Width stay the same and length decrease

The double-slit experiment with electrons illustrates the surprising idea that A. electrons sometimes behave like tiny particles. B. the microscopic behavior of matter is entirely predictable. C. light is a wave D. electrons sometimes behave like waves. E. light is composed of tiny particles.

D. electrons sometimes behave like waves.

Velma passes Mort at a high speed. Each holds a meter stick, oriented parallel to the direction of relative motion. Mort observes that A. his meter stick is longer than 1 m, and Velma's meter stick is 1 m long. B. his meter stick and Velma's meter stick are both shorter than 1 m. C. his meter stick is 1 m long, and Velma's meter stick is longer than 1 m. D. his meter stick is 1 m long, and Velma's meter stick is less than 1 m long. E. his meter stick and Velma's meter stick are both 1 m long.

D. his meter stick is 1 m long, and Velma's meter stick isless than 1 m long.

When we say that an electromagnetic field is "quantized," we mean that it A. it is really made of particles known as electrons. B. it fills up a region of space. C. it is really made of particles known as photons. D. is allowed to have only certain particular values of total energy. E. it vibrates at one particular frequency.

D. is allowed to have only certain particular values of total energy.

22) Which of the following processes will increase the mass of the system? A) A rock is made to move faster and faster. B) Two magnets that are initially held together by their magnetic forces are separated. C) Both of the above. D) A cup of coffee is heated. E) All of the above

E) All of the above

30) Which of the following is a consequence of Heisenberg's uncertainty principle? A) The uncertainties involved in determining a person's genetic inheritance when DNA molecules are combined. B) The overall layout of the universe. C) Both of the above. D) The unpredictability of radioactive decay. E) All of the above.

E) All of the above.

14) The wave that arises in experiments such as the double-slit experiment with electrons is best described as A) a wave of electric charge. B) a pressure wave. C) a heat wave. D) an electromagnetic wave. E) a matter wave

E) a matter wave

26) One unusual aspect of dark matter is A) it exerts a new kind of fundamental force, never observed before. B) it moves faster than lightspeed. C) it exerts no gravitational force. D) its gravitational force pushes (or repels) instead of pulling. E) it does not interact with electromagnetic radiation.

E) it does not interact with electromagnetic radiation.

In quantum theory, a "wave packet" A) represents one particle having a range of possible positions but a specific velocity. B) represents many particles, each one having both a specific position and a specific velocity. C) represents many particles, each one having a range of possible positions and a range of possible velocities . D) represents one particle having a specific position but a range of possible velocities. E) represents one particle having a range of possible positions and a range of possible velocities.

E) represents one particle having a range of possible positions and a range of

28) In the context of the double-slit experiment, quantum nonlocality refers to A) the fact that the electron beam or light beam goes through both slits rather than only one. B) our inability to precisely predict the point at which a spread-out matter field or EM field will interact with the screen. C) the fact that each interaction with the screen occurs over a broad area of the screen. D) the fact that the particles of matter or radiation are instantaneously replaced by a spread-out matter field or EM field when the particles impact the screen. E) the fact that the entire matter field or EM field instantaneously collapses to the single interaction point when the field interacts with the screen

E) the fact that the entire matter field or EM field instantaneously collapses to the single interaction point when the field interacts with the screen

Which of the following is a consequence of Heisenberg's uncertainty principle? A. The uncertainties involved in determining a person's genetic inheritance when DNA molecules are combined. B. The overall layout of the universe. C. Both of the above. D. The unpredictability of radioactive decay. E. All of the above.

E. All of the above.

What does Mort actually observe in the preceding question? A. 0.25c and 1.75c B. 1.75c and 0.25c C. 0.25c and 0.75c D. 0.75c and 0.25c E. c and c

E. c and c

Intergalactic matter

Empty space between galaxies as a lot of hydrogen

Principle of Relativity

Every non-accelerated observer observes the same laws of nature. In other words, no experiment performed within a sealed room moving at an unchanging velocity can tell you whether you are standing still or moving

Thought Experiment 1 Velma in rocket, Mortimer on Earth Rocket at speed of 0.25c away from Mortimer Velma points a laser forward Velma sees light moving at what speed? c or 300,000 km/s Mortimer sees light moving at what speed?

Galilean relativity would say 1.25c Einstein's relativity would say c

Special Theory of Relativity

Known as Einstein's relativity Principle of Relativity; laws same in all frames Lightspeed constant in all frames As long as the reference frames are NOT accelerating

Quantum events cannot be predicted

Nature doesn't know ahead of time what the result is going to be Can't predict location of impact

Galilean Relativity

No speed limit Everyday relativity Velma on moving train and throws a ball toward frontof train Mortimer on ground and watches ball thrown Do Velma and Mortimer see the ball travel at the same speed? strain = 70 m/s sball = 20 m/s on train How fast does Mortimer see the ball traveling? Ground: sball=20m/s+70m/s

Two Forms of Relativity

Special Theory of Relativity General Theory of Relativity

Uncertainty Principle

The position and velocity of every material particle are uncertain. Although either uncertainty can take on any value, its product must approximately equal Planck's constant divided by the particles mass. In symbols DELTA X TIMES DELTA V = H/ M Uncertainty principle relates uncertainties to mass of the particle

If you are watching a system moving relative to you:

Time is lengthened in the moving frame. Mass increases in the moving frame. Distance is shortened in the moving frame if the distance is parallel to the motion.

Simple clock - Light Clock

Two parallel mirrors: 150,000 km apart Light pulse travels from one to other and back In one second light makes one round trip; tick Every second, light travels 300,000 km

Neutrinos

Very light particles that don't interact with light but do interact a little

What about acceleration - can this be detected without looking outside? A. Yes, you can do a simple experiment to tell B. Yes, but the experiment involves light C. No

a

Constant light speed is

a law of nature.

Maxwell

all disturbances in electromagnetic fields travel at c

Einstein:

all laws of nature should be the same in all reference frames Electromagnetic waves move at c in all frames Regardless of the speed of the frame

Newton's law of motion;

allows predictions of future from past

Theory of Relativity

answers questions concerning observers in relative motion; observers in different reference frames

Mass increases, uncertainty ______________

decreases

Electrons form an

interference pattern

Symmetry principle:

laws of physics are the same in any reference frame moving at constant velocity Constant speed Constant direction

Reference Frame

location from which an observer makes an observation

Relative Motion

observers moving at different velocities

Quantum physics;

position and velocity not precisely known; uncertainty is related Quanta of energy in a matter field spread over x and v Reduce one the other must increase h/m similar to area

Galactic matter

stars, planets gas clouds Luminous

Quantum physics

very small

Particles of matter exhibit

wave properties