Tuesday, March 9, 2010
461: "Simply Einstein..." 2004 reading notes
Hubble Telescope photo; Photo of Charlie Chaplin and Albert Einstein, 1931, from website of Dr. Andreas Aste, University of Basel.
The Hebrew University (see them online at http://www.huji.ac.il/huji/eng/) will be celebrating Mr. Einstein with events on campus and online through March 2010. Mr. Einstein took personal interest in The Hebrew University, left many of his papers to the Israeli school; my scruffy copy from internet of Einstein's June 30, 1905 paper, "On the Electrodynamics of Moving Bodies."
Undated, unpublished reading notes by Lurene Helzer, undated, but likely early 2004 notes.
Lurene's email in 2014: email@example.com
The book (on tape) was “Simply Einstein: Relativity Demystified” by Richard Wolfson, published in late 2003 by W.W. Norton and Co. in New York.
I do not remember why I decided to check out the Wolfson book, but I was obviously looking for something energizing to read in early 2004. I found these notes in scrap box just today, February 28, 2010.
I like such notes for my blogs because it gives people an opportunity to discover the magic of physics and philosophy. While taking these fun notes in 2004, I felt like a child watching cartoons Saturday morning.
I thought I'd studied relativity while at the Hebrew University of Jerusalem as a visiting student, but I reviewed my records in July of 2010 and see the class on relativity was actually taken by me at San Francisco State University, Fall 1988. Still, in 2010 I enjoy re-learning Einstein's theories at libraries.
It was a summary course for science-outsiders like me; I did some routine study, but no memorable writing about physics or Albert Einstein while in school. (These quick-style notes should be for glancing only. Those truly curious should examine the book by Mr. Wolfson, or Mr. Einstein's works.)
But the course planted with me a genuine interest in physics and, by extension, philosophy. Physics and philosophy are closely related, as this book cheerfully reminded me once again:
PHYSICS AND PHILOSOPHY
1 -- “THE PROBLEM OF GRAVITY”
PROF. R. WOLFSON
Gen. Theory of Relativity is about gravity. The same laws of physics for all references. The same for all observers. When dealing with acceleration, it changes. Newton laid down general principles of gravity. But unsatisfying for special relativity. Problem with distances, which are not always well defined. Depends on observer. [like consciousness.]
General Relativity – Galileo discovers force of gravity same on two objects. Same acceleration, regardless of mass. The force of gravity proportional to object’s mass. Weight related directly to mass. They fall at same rate – tennis ball and basketball – because one has more gravitational mass than the other.
Einstein said principle of equivalence says effects of gravity and acceleration indistinguishable. Falling ball in elevator example. Astronauts seem weightless because they are accelerating with/inside an object. Both are falling. Uniform motion. We can “eliminate” gravity in free fall. Until one drops, that is.
Freefalling is the closest we can come to the frame of reference to gravity free frame.
EINSTEIN’S RELATIVITY AND QUANTUM REV.
General Theory – theory of gravity, laws of physics same for all observers? No. Un-Uniform, accelerating motion is the case with Einstein’s case scenario.
Newton’s theories don’t work in wider spheres because action is delayed over distance, and distance calculations can be relative to the observer.
Goes back to Galileo, saying things fall at same speed. Force of gravity proportional to its mass.
Inertial Mass – equivalent w/Gravitational mass same thing. “Principal of Equivalence.” This means a man in a falling elevator has same speed of falling than elevator, man, and ball he takes out of his pocket.
Weightlessness in space is because they are all being accelerated at same rate. Falling freely is still under influence of gravity.
OR if one is acting OUTSIDE gravity, in interstellar space, there is weightlessness.
This is what is meant by principle of equivalence.
Free fall is closest we can come to uniformly-moving frame of reference.
Time does not have an objective reality, as is [does] gravity. It’s not real.
Tidal forces are real, falling objects stretch and move closer together. This is dramatic with large sources of gravity. Geometry of space-time forces two balls together as they fall. The geometry of the universe is not normal. It is curved. Ball (curved) vs. flat board (Euclid).
Straightest possible line in curved space-time is how an object moves. That’s why airplane has to use different lines than a falling board.
Parallel straight lines intersect in curved space-time. This is why two falling objects converge as they fall close to earth.
Gravity IS the curve of space-time.
What causes space-time to curve? Matter and energy. General theory – published 1914.
Math for curved space-time is non-Euclidian – very complex. This describes laws of physics. Einstein developed this theory by himself. He had to try experimental math, because no way to prove it.
SpaceTime is four-dimensional.
Large and small ball on saran-wrapped surface. The small ball is moving in the straightest possible path in its curved space-time field. This is the geometry of space-time.
So what predictions from relativity? In places where gravity is not weak, where Einstein is relevant, things are different.
Orbital Precession -- Happens in solar system – Mercury. Mercury is closest to sun. Orbital behavior of Mercury just a bit different. 1/100s degree of angle per century.
Neutron Star, very dense, or Pulsars – collapsed stars. Very massive.
Time runs slower where gravity is strong, or space-time is greatly curved. 1960 – 74-foot tower experiment. Saw shift in decay of atom.
Can also see slower emissions from compact bodies like the sun.
This should not be confused with regular time dilation.
This is practical when working with satellites. Relativity is abstract, but relevant.
General relativity predicts light must be bent.
< LIGHT BEAM >
STAR SUN EARTH
Beam of light [represented by arrows above] is bent by gravity.
Gravitational Lensing – Caught by Hubble Space Telescope. Einstein Cross.
Micro Lensing, Gravitational waves, go the speed of light.
Special relativity predicts black holes, too. #
Gravity decreases with distance – its force weakens. Takes finite amount of energy to escape gravity. There is an escape speed – 7 miles a second for earth. Escape speed from sun is more. [400 m – per second from the sun.] After it escapes, it keeps going.
Concentration of mass – works on escape speed. Can be so dense that even light cannot escape.
It takes major compression to make gravity that strong.
A Black Hole – not even light can escape – Gravity too intense.
Event horizon – point of no return by Black Hole.
Gravitational Time Dilation – at event horizon, time dilation infinite.
Russians call them Frozen Stars.
We don’t see what happens past event horizon because of time dilation. They don’t suck things in, but if you run into one, you can’t go back.
You would be crushed inside hole, eventually. But you’re in “infinite future.” – all of eternity has passed back home after you fall into black hole.
Supernovas are the end of stars. We are made from material from Supernova. Can’t sustain itself against its own gravity, which is why it must turn into Frozen Star.
Binary Star system – Black Hole, accretion disk, distorted star, x-rays, as stream.
Newton’s, Einstein’s, laws tell us what a black hole is. Energy emitted is less, or about to be absent.
Black Holes are standard in space. But scientists did not easily accept them. They’re bizarre. Very massive black holes in most or all galaxiesm, including our own. Compact, but contain matter of 40 million plus suns. Quasars may be black holes at heart.
Mass, charge, rotation speed. That’s all they mean. They destroy everything that goes in.
Wormholes may exist though black holes, but who knows? Black holes are simply bizarre. #
INTO HEART OF MATTER
In quantum realm, our language is insufficient. It is more abstract. Realm of philosophy.
Quantum physics: About the nature of matter. Sub-atomic world. Makes the stuff of which we are constructed, and live. Very small, very large. Deep, profound philosophical questions. String theory.
Democritus – atoms, indivisible, made up universe, he said. 460 – 370 bce. Greek. First description of atomic theory. Atoms, he said, indivisible.
1766-1844 John Dalton, arranged elements by atomic weight.
No. of electrons-charged-Atomic No.
Dmitri Mendeleev [Менделеев] 1834 – 1907 Russian
mass of atom is atomic weight.
Mendeleev made Periodic Table of the Elements – by # of electrons. How it reacts w/other atoms. Chemistry.
Becquerel 1852 – 1908; Uranium, film image. Discovered radioactive material.
Curries – discovered other properties of radiation. Discovered atoms are dividable.
Cathode Rays – JJ Thompson, born 1856 – died 1940 – discovered electron.
Lord Kelvin – “Plum Pudding” 1900. Atoms have no charge, but electrons in atom make it neutral??
Matter comes in discrete chunks/packets.
1909-1911 Rutherford in England. Particle tracks. Could not accelerate particles, but used radioactive particles. Gold foil. Geiger was his partner. All alpha particles went through, some did not go through gold foil. Marsten, too, was scientist. They said there must be nucleus in atom that carries most of the mass. 1911. More like a solar system. Now, matter was being discovered more as it is, though it’s still early in science.
Problems: Energy in Rutherford’s atom is not explainable and colors it emits are strange, inconsistent. Also, color shifts. Red – toward yellow – blue – ultra violet. “Ultra-Violet Catastrophe.” #
Classical physics in question by turn of century. The photoelectric effect, senses light differently.
Quantum Mechanics: Wave or Particle?
Is light a wave or particle? 1629-1695 – Huygens – 1600s – worked on light
Thomas Young 1775-1829 – Wave interference. Slits. Light must be particles…Continue later in notes #
Energy of Light is in Photons. Almost as if light is a particle. Einstein said light behaves like particles. Light bounces, bends, produces color. Wave Interference experiment. Screen and barrier. You get two patterns of semi-circular waves. Places were wave crests and troughs meet. Destructive and constructive interference. Alternating light, dark bands show on screen. Red and green lights have separate patterns. Maxwell, 1860s, showed magnetic fields. Light bundles are photons, Einstein says. So, in 1905, light is dual, in the way that science understood it.
Compton – hit electron with X-rays electromagnetic wave. Classical explanation of scattering. But quantum, says electron hit by photon, photon loses some energy, goes to lower wavelengths. Called “Compton Shift.” This is particle behavior.
So, which is it? Particle or wave? Quantum physics says both.
If you take same barrier, block one slit, no wave behavior. Particle like because you’ve destroyed interference pattern! Alternating bands of light on screen.
So light is wave and particle. No way around it. It does both things. The photons “know” what you’re doing! More likely to find photon with strong light. Probability depends on amplitude of light. The connection between two is fuzzy. Complimentary aspects of the same reality, Niels Bohr. Not contradiction. Never both behaviors, light, particle, at same time. It depends on what you want to do with the light. Complimentary Principle of Light.
This seemed absurd: 1901-1976 Hiesenberg; Can nature be as absurd as it appears to us in these atomic experiments? #
QUANTUM UNCERTAINTY, TAPE 2
Heisenberg uncertainty principle. There’s a limit to the amount of investigation we can do in our investigations, because we affect the result by examining it.
Wave Packet – Broad or narrow, varying frequencies. Broad – Photon not localized, long wavelength, low freq.
Narrow – Photon localized, short wave length, high frequency.
Quantum Light Experiment – Shine light on electron. Detect where electron is. “A Thought Experiment.” Localize photon first, interacts with electron. Unfortunately, though, the high frequency electron is disturbed by high energy photon, takes off with unknown velocity.
So, you destroy the information. Can try lower frequency, minimize disturbance. But, photon was not localized, don’t know where electron was, is.
Can’t measure Position and Velocity. Not simultaneously. Not with high precision.
The product of the uncertainty in position with the uncertainty in momentum (mass x velocity) cannot be less than Planck’s Constant h.
▲V – How uncertain? What is velocity and how uncertain is it? = h
M = mass
▲x – Uncertainty of position
Mass /times uncertainty of position/uncertainty of velocity > h Planck’s Constant (33 zeros) 1/1,000,000,000,000…..
It’s the smallness involved in h that makes it so uncertain. You don’t know where anything is.
Logical Positivism – Philosophy that says immeasurable things are not worth talking about. Copenhagen Interpretation. Most physicists subscribe to this interpretation. Or they do quantum mechanics and try not to ponder philosophy of it at all, because Quantum is useful in real world! It makes no sense to say it has a given Velocity.
Language fails us in quantum mechanics. Niels Bohr – Copenhagen position. Electron is uncertain, fuzzy. You can’t give precise information. We can’t determine future behavior. Farewell to the determined, clockwork universe.
Bohr, Einstein disagreed. E. said “God doesn’t play dice.”
“It is hard to sneak a look at God’s cards, but that he would play dice with the world is something I cannot believe for a single moment.”
Other physicists, philosophers working still on Einstein.
Many now say it looks like E. was wrong. It looks like Quantum Mechanics has given us a new, strange philosophical picture of the world. Very imprecise, fuzzy. #
PARTICLE OR WAVE
Light is both particle and wave. But matter? 1923 de Broglie. Wavelength of particles associated with particle.
H – Planck’s Constant
Wavelength = ―
MV – Particle mass times its speed
There’s a limit to how much you can subdivide things. Wavelength is difference between two wavecrests: ~~~~~
Light travels in wavelengths far different than the wavelengths of sound. Light is pretty small.
Even a moving tennis ball has a wavelength, small, we do not notice, because it’s matter. But for atoms, or electron, the wavelength is comparable to the size of the object itself. Quantum effects. Absolute Zero temperature will slow down wavelength activity. Low-Temp Physics – Double slit experiment. So, light and matter are both wave and particle. Beautiful symmetry. Both light and matter have aspects of wave behavior.
Erwin Schrodinger 1887-1961
1926, E.S. came up with equation for matter waves. It gives us probability that we’ll find particle, or electron. Where wave is big, we’ll find matter particle. This is view of Quantum Physics. Classical physics wanted particle behavior equation and wave behavior equation. Now, the wave equation told us probability of finding a particle.
We gain understanding of orbits in atoms for electrons. Allowed orbits, strings that connect.
Quantum Tunneling – Matter wave easily found between barriers. Harder to find particle outside barrier.
Quantum Tunneling device – coral – using absolute zero temps. Trap electrons inside barrier.
Matter wave – continuous. Wavelength, hence velocity, precisely known. Infinite uncertainty about where particle is. But wave packet, position well known. Have to use many wavelengths, though. So you can’t measure both wave and particle aspects simultaneously. Uncertain and fuzzy. #
SCHRODINGER’S CAT AND QUANTUM WEIRDNESS:
Super-position state. Wave nature is important. Two waves is a superposition. Ambiguous states. Electron is in a superposition when talking about waves. Can’t have an atom in between, electron. Lower or upper. Mix of two possible positions of electron.
But measuring it forces it into one of two states. Wave behavior vanishes. What, then, does measurement mean? It interacts with system itself! Forces system in definite state.
So, process of measurement destroys what you were trying to gauge. Lose old properties of system. When you are not looking at it, you put atom in a definite place. Before, it was equally likely to be in either of 2 places.
Can this have bearing on macroscopic world? Schrodinger’s Cat experiment. This is example of Quantum laws affecting every day world because 50/50 chance of cat dying of radioactive effects. Random Event. Not clockwork. Not deterministic. No going deeper than 50/50 in quantum world. [note from Lurene: I’ve never quite accepted this theory, but enjoy learning about it.]
But according to Copenhagen school, it’s in both places. Cat is half-dead, half-alive. Strict interpretation. But if you open the box, it determines a posit. Because when you open box, wave system is collapsed. Then, further question of cat’s consciousness as part of quantum system.
Does universe bifurcate between two possibilities? Does universe split into each possible outcome? Multiple universes, one for each outcome possible? Put yourself in cat’s position? Many world theory. Both/all universes are realized each time I open the box. Logically consistent with quantum physics.
Where is boundary between classical and Quantum? Where is mid-scale – is that where consciousness is? Between the classical, Quantum world system of physics?
EINSTEIN, PODOLSKY, ROSEN EXPERIMENT –
Particle with undetermined spin. If I determine spin as up, right is down. Before it went through detector, though, it was indeterminate. As if the two particles communicate. Copenhagen interpretation of Q. Mechanics.
In 1964 in Switzerland, John Bell, put second spin detector in play. Showed spin is created by measurement itself. Now, different locations in Switzerland show same dynamic. [For example, measuring spin of particle in Hayward determines spin orientation of particle in Fremont. ]
“Spooky action at a distance,” said Einstein.
We don’t know what the spin is going to be, however. Somehow, 1st and 2nd particle, even at a distance, are connected in Quantum way. Big realization for theosophy and philosophy, especially. ##
THE PARTICLE ZOO
By 1990s, complete theory developed. Particle physics. The structure of matter; Molecules; Atoms; electron; electron appears to be structureless.
Can’t take it apart. Building block of universe probably. Lasts forever. Rutherford.
Nucleus is atom, composed of nucleons, which are Protons (H) and Neutrons (neutral). Protons, neutrons made up of Quarks. Quarks carry fractional electron charge. Up and down Quarks. Gives each a charge. Quarks are probably structureless. Quarks and electrons. Quarks up or down charge. Electrons, quarks fundamental building blocks of universe. Neurons not stable.
Quarks/Anti-Quarks = Mezzans.
All this held together by “force.” 3 fundamental forces:
1) Gravity. Weakest force. Geometry of Spacetime. More apparent in presence of enormous bodies of matter.
2) Electroweak Force, electromagnetic force, magnetic force, weak force-nuclear. Aspect of force.
3) Color Force – Binds Quarks. Can’t do this. Does not decrease with distance. So you will never see an isolated quark.
Standard model: Leptons, neutrinos – which hardly interact with matter at all. Very small mass. Particles in Standard Family model:
1st Family 2nd 3rd
Up Quark charmed Quark Top Quark
Down Quark Strange Quark Bottom Quark
Electron Muon Tan
Electron- muon-neutrino tan neutrino (2)
(1) All necessary for standard matter, approximately
(2) Tan neutrino can oscillate to other neutrino forms to left, i.e., electron-neutrino or muon-neutrino
Only the first family stable. Other two play modest, unstable role. Early universe had more role for 2nd, 3rd family.
Force carrier – Virtual photon → Photon. Virtual photon is temporary particle. Other force carrying particles – W, Z boson, gluon for color force. Gravitation for gravity force.
Graviton is a shady subject in quantum. Particle accelerator in Switzerland will shed more light on these particles. [March 9, 2010 note from Lurene: We presume.] #
Our universe is expanding, and has certain beginning. Edwin Hubble – 1889-1953 – finds all galaxies moving away. Further away, moving faster. Knew this from sound wave frequencies – Doppler effect.
what happened in past if galaxies are expanding, 12-15 billion years ago, Universe began – big bang.
Theory – Cosmic Microwave Radiation. 1960s. Cosmic Microwave Background remnants. Fuzz on television is this. Very old.
Advances in particle physics – confirmed big bang theory.
Universe starts out incredibly dense. Cosmic Timeline: Planck time, Quantum Gravity…Cosmic inflation…Protons, Neutrons form…Helium Nucliei form…etc.
Universe overall 75% Hydrogen, Helium, etc.
Then, Atoms form after Nuclei are formed. Universe emits electromagnetic radiation. Fossil remnant of universe still there now. 100 million years after B. Bang, galaxies form. 5 billion years ago – Earth forms. 10 Billion, 15 Billion years out, intelligence forms. Many physicists believe it is natural outcome of matter made intelligence in lots of other places, too.
Cosmic Futures – Universe expands forever. Spacetime curved OR just barely expands forever OR universe eventually collapses.
Expansion could be accelerating, too. Recycled Einstein theories that he threw out.
Dark Matter – We do not know what it is. Most of matter we don’t even know about, probably. We might be insignificant.
We are children of big bang. Star children, literally.
Dyson – said intelligence could continue to exist and communicate with itself. Princeton.
Intelligence once established continues to exist.#
TOWARD A THEORY OF EVERYTHING
We have no idea of WHY things are as they are. WHY? Why are there 3 forces? We DO have Theory of Relativity, and Quantum Physics. We don’t have theory that puts those 2 together. We’ve never had reason to have to use them together.
“Quantum Gravity” is this theoretical missing discipline. When would this matter? At center of Black Hole.
Richard Feynman – 1918-1988 – Quantum electrodynamics – Theory of Physical Reality. Other than black hole, beginning seconds of universe Quantum gravity would be relevant, if we could do it.
History of Physics – Unification of Physical Forces
Things are more complex now than they were at beginning.
Electricity and Magnetism lead to Electromagnetism. From there, we see Electroweak Force, Weak Force in Nuclear Reactions, important to Sun, Color Force (Binds Quarks), Theory of Grand Unified Force, THEORY OF EVERYTHING….
Force underlying all others, String Theory.
String, vibrates, Planck length, all matter. Tiny, tiny entities. Nothing smaller. 1970 theory. 1995 stunning breakthroughs in String Theory.
Strings vs. Particles. If particles were loops of string, interaction is continuous. No unique point in spacetime.
String theory – 10 space dimensions, one time. THE ELEGANT UNIVERSE.
11 dimensions in total instead of 4, like compactified tube. Curled up. Strings vibrate.
Is this the end of physics? No. We still use classical physics, usually. Also, there may be other eras with new realities, and dark matter. Also, there is a rich future unfolding.
Probably no conceivable end to physics. ## END OF ALL TAPES/COURSE
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