Einstein’s Revenge

Vinnie’s always been a sucker for weird-mutant sci-fi films so what Jennie says gets him going.  “So you got these teeny-tiny neutrinos and they mutate?  What do they do, get huge and eat things?”

“Nothing that interesting, Vinnie — or uninteresting, depending on what you’re keen on.  No, what happens is that each flavor neutrino periodically switches to another flavor.”

“Like an electron becomes a muon or whatever?”

“Hardly.  The electron and muon and tau particles themselves don’t swap.  Their properties differ too much —  the muon’s 200 times heaver than the electron and the tau’s sixteen times more massive than that.  It’s their associated neutrinos that mutate, or rather, oscillate.  What’s really weird, though, is how they do that.”

“How’s that?”

“As I said, they cycle through the three flavors.  And they cycle through three different masses.”

“OK, that’s odd but how is it weird?”

“Their flavor doesn’t change at the same time and place as their mass does.”Neutrino braid with sines

“Wait, what?”

“Each kind of neutrino, flavor-wise, is distinct — it reacts with a unique set of particles and yields different reaction products to what the other kinds do.  But experiments show that the mass of each kind of neutrino can vary from moment to moment.  At some point, the mass changes enough that suddenly the neutrino’s flavor oscillates.”

“That makes me think each mass could be a mix of three different flavors, too.”

“Capital, Vinnie!  That’s what the math shows.  It’s two different ways of looking at the same coin.”

“The masses oscillate, too?”

“Oh, indeed.  But no-one knows exactly what the mass values are nor even how the mass variation controls the flavors.  Or the other way to.  We know two of the masses are closer together than to the third but that’s about it.  On the experimental side there’s loads of physicists and research money devoted to different ways of measuring how neutrino oscillation rates depend on neutrino energy content.”

“And on the theory side?”

“Tons of theories, of course.  Whenever we don’t know much about something there’s always room for more theories.  The whole object of experiments like IceCube is to constrain the theories.  I’ve even got one I may present at Al’s Crazy Theory Night some time.”

“Oh, yeah?  Let’s hear it.”

“It’s early days, Al, so no flogging it about, mm?  Do you know about beat frequencies?”

“Yeah, the piano tuner ‘splained it to me.  You got two strings that make almost the same pitch, you get this wah-wah-wah effect called a beat.  You get rid of it when the strings match up exact.”  He grabs a few glasses from the counter and taps them with a spoon until he finds a pair that’s close.  “Like this.”

“Mm-hmm, and when the wah-wahs are close enough together they merge to become a note on their own.  You can just imagine how much more complicated it gets when there are three tones close together.”

I see where she’s going and bring up a display on Old Reliable —an overlay of three sine waves.   “Here you go, Jennie.  The red line is the average of the three regular waves.”Three sines on Old Reliable“Thanks, Sy.  Look, we’ve got three intervals where everything syncs up.  See the new satellite peaks half-way in between?  There’s more hidden pattern where things look chaotic in the rest of the space.”

“Yeah, so?”

“So, Vinnie, my crazy theory is that like a photon’s energy depends on its wave frequency in the electromagnetic field, a neutrino is a combination of three weak-field waves of slightly different frequency, one for each mass.  When they sync up one way you’ve got an electron neutrino, when they sync up a different way you’ve got a muon neutrino, and a third way for a tau neutrino.”

I’ve got to chuckle.  “Nothing against your theory, Jennie, though you’ve got some work ahead of you to flesh it out and test it.  I just can’t help thinking of Einstein and his debates with Bohr.  Bohr maintained that all we can know about the quantum realm are the averages we calculate.  Einstein held that there must be understandable mechanisms underlying the statistics.  Field-based theories like yours are just what Einstein ordered.”

“I could do worse.”Neutrino swirl around Einstein

~~ Rich Olcott

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Prelude to A Shell Game

Big Vinnie barrels into the office.  “Hey, Sy, word is that you’ve been trash-talking Niels Bohr.  What’s the story?”

“Nothing against Bohr, Vinnie, he was a smart guy who ran a numbers game out of C-town —”

“Which C-town, Cincy or Cleveland?”

“Copenhagen.  But he got caught short at payoff time.  Trouble is, some people still think the game’s good which it’s not.”

Hydrogen spectrum

Hydrogen spectrum, adapted from work by Caitlin Jo Ramsey
(CC BY-SA 3.0)
via Wikimedia Commons

“Which numbers game was this — policy, mutuale, bolita?”

“Rydberg.”

“Never heard of that one.”

“Rydberg was a Swedish physicist in the late 1800s.  He systemized a pile of lab and astronomy data about how hydrogen gas interacts with light.  Physicists like Lyman and Balmer showed how hydrogen’s complicated pattern (the white lines on black on this diagram) could be broken down to subsets that all have a similar shape (the colored lines).  Rydberg found a remarkably simple formula that worked for all the subsets.  Pick a line, measure its waves per meter. There’ll be a pair of numbers n1 and n2 such that the wave count is given by  Rydberg equationZ is the nuclear charge, which they’d just figured out how to measure, and R is a constant.  Funny how it just happens to be Rydberg’s initial.”

“Any numbers?”

“Small whole numbers, like 1, 2, up to 20 or so.  Each subset has the same n1 and a range of values for n2. The Lyman series, for instance, is based on n1=1, so you’ve got 1/1–1/4=3/4, 1/1–1/9=8/9, 15/16, 24/25, and so on. See how the fractions get closer together just like those lines do?”

“Nice, but why does it work out that way?”

“Excellent question, but no-one had an answer to that for 25 years until Bohr came up with his model.  Which on the one hand was genius and on the other was so bogus I can’t believe it’s still taught in schools.”

“So what did he say?”

“He suggested that an atom is structured like a solar system, planar, with electrons circling a central nucleus like little planets in their orbits. Unlike our Solar System, multiple electrons could share an orbit, chasing each other around a ring.  The 1/n² numbers are the energies of the different orbits, from n=1 outwards.  An electron in a close-in orbit would be tightly held by the nuclear electrical field; not so much for electrons further out.”

“Yeah, that sounds like what they taught us, alright.”

“Bohr then proposed that an incoming lightwave (he didn’t believe in photons) energizes an electron, moves it to a further-out orbit.  Conversely, a far-away electron can fall inward, emitting energy in the form of a lightwave.  Either way, the amount of energy in the lightwave depends only on the (1/n1²–1/n2²) energy difference between the two orbits.  The lightwave’s energy shows up in that wave number — more energy means more waves per meter and bluer light.”

“Ah, so that Ly series with n1=1 is from electrons falling all the way to the lowest-energy orbit and that’s why it’s all up in the … is that ultra-violet?”

“Yup, and you got it.  The Balmer series is the one with four lines in the visible.”

“Uhh… why wouldn’t everything just fall into the middle?”

“Bohr said each orbit would have a capacity limit, beyond which the ring would crinkle and eject surplus electrons.  He worked out limits for the first half-dozen elements but then things get fuzzy, with rings maybe colliding and swapping places.  Not satisfactory for predictions.  Worse, the physics just doesn’t work for his basic model.”No Bohr

“Really?  Bohr was a world-class physicist.”

“This was early days for atomic physics and people were still learning what to think about.  The Solar System is flat, more or less, so Bohr came up with a flat model.  But electrons repel each other.  They wouldn’t stay in a ring, they’d pop out to the corners of a regular figure like a tetrahedron or a cube.  That’d blow all his numbers.  The breaker payout, though, is his orbiting electrons must continually radiate lightwaves but don’t have an energy source for that.”

“Was he right about anything?”

“The model’s only correct notion was that lightwaves participate in shell transitions.  Schools should teach shells, not orbits.”

~~ Rich Olcott

Abstract Horses

It was a young man’s knock, eager and a bit less hesitant than his first visit.

“C’mon in, Jeremy, the door’s open.”

“Hi, Mr Moire, it’s me, Jerem…  How did ..?  Never mind.  Ready for my black hole questions?”

“I’ll do what I can, Jeremy, but mind you, even the cosmologists are still having a hard time understanding them.  What’s your first question?”

“I read where nothing can escape a black hole, not even light, but Hawking radiation does come out because of virtual particles and what’s that about?”

“That’s a very lumpy question.  Let’s unwrap it one layer at a time.  What’s a particle?”

“A little teeny bit of something that floats in the air and you don’t want to breathe it because it can give you cancer or something.”

“That, too, but we’re talking physics here.  The physics notion of a particle came from Newton.  He invented it on the way to his Law of Gravity and calculating the Moon’s orbit around the Earth.  He realized that he didn’t need to know what the Moon is made of or what color it is.  Same thing for the Earth — he didn’t need to account for the Earth’s temperature or the length of its day.  He didn’t even need to worry about whether either body was spherical.  His results showed he could make valid predictions by pretending that the Earth and the Moon were simply massive points floating in space.”

Accio abstractify!  So that’s what a physics particle is?”

“Yup, just something that has mass and location and maybe a velocity.  That’s all you need to know to do motion calculations, unless the distance between the objects is comparable to their sizes, or they’ve got an electrical charge, or they move near lightspeed, or they’re so small that quantum effects come into play.  All other properties are irrelevant.”

“So that’s why he said that the Moon was attracted to Earth like the apple that fell on his head was — in his mind they were both just particles.”

“You got it, except that apple probably didn’t exist.”

“Whatever.  But what about virtual particles?  Do they have anything to do with VR goggles and like that?”

“Very little.  The Laws of Physics are optional inside a computer-controlled ‘reality.’  Virtual people can fly, flow of virtual time is arbitrary, virtual electrical forces can be made weaker or stronger than virtual gravity, whatever the programmers decide will further the narrative.  But virtual particles are much stranger than that.”

“Aw, they can’t be stranger than Minecraft.  Have you seen those zombie and skeleton horses?”Horses

“Yeah, actually, I have.  My niece plays Minecraft.  But at least those horses hang around.  Virtual particles are now you might see them, now you probably don’t.  They’re part of why quantum mechanics gave Einstein the willies.”

“Quantum mechanics comes into it?  Cool!  But what was Einstein’s problem?  Didn’t he invent quantum theory in the first place?”

“Oh, he was definitely one of the early leaders, along with Bohr, Heisenberg, Schrödinger and that lot.  But he was uncomfortable with how the community interpreted Schrödinger’s wave equation.  His row with Bohr was particularly intense, and there’s reason to believe that Bohr never properly understood the point that Einstein was trying to make.”

“Sounds like me and my Dad.  So what was Einstein’s point?”

“Basically, it’s that the quantum equations are about particles in Newton’s sense.  They lead to extremely accurate predictions of experimental results, but there’s a lot of abstraction on the way to those concrete results.  In the same way that Newton reduced Earth and Moon to mathematical objects, physicists reduced electrons and atomic nuclei to mathematical objects.”

“So they leave out stuff like what the Earth and Moon are made of.  Kinda.”

“Exactly.  Bohr’s interpretation was that quantum equations are statistical, that they give averages and relative probabilities –”

“– Like Schrödinger’s cat being alive AND dead –”

“– right, and Einstein’s question was, ‘Averages of what?‘  He felt that quantum theory’s statistical waves summarize underlying goings-on like ocean waves summarize what water molecules do.  Maybe quantum theory’s underlying layer is more particles.”

“Are those the virtual particles?”

“We’re almost there, but I’ve got an appointment.  Bye.”

“Sure.  Uhh… bye.”

~~ Rich Olcott

Reflections in Einstein’s bubble

There’s something peculiar in this earlier post where I embroidered on Einstein’s gambit in his epic battle with Bohr.  Here, I’ll self-plagiarize it for you…

Consider some nebula a million light-years away.  A million years ago an electron wobbled in the nebular cloud, generating a spherical electromagnetic wave that expanded at light-speed throughout the Universe.

Last night you got a glimpse of the nebula when that lightwave encountered a retinal cell in your eye.  Instantly, all of the wave’s energy, acting as a photon, energized a single electron in your retina.  That particular lightwave ceased to be active elsewhere in your eye or anywhere else on that million-light-year spherical shell.

Suppose that photon was yellow light, smack in the middle of the optical spectrum.  Its wavelength, about 580nm, says that the single far-away electron gave its spherical wave about 2.1eV (3.4×10-19 joules) of energy.  By the time it hit your eye that energy was spread over an area of a trillion square lightyears.  Your retinal cell’s cross-section is about 3 square micrometers so the cell can intercept only a teeny fraction of the wavefront.  Multiplying the wave’s energy by that fraction, I calculated that the cell should be able to collect only 10-75 joules.  You’d get that amount of energy from a 100W yellow light bulb that flashed for 10-73 seconds.  Like you’d notice.

But that microminiscule blink isn’t what you saw.  You saw one full photon-worth of yellow light, all 2.1eV of it, with no dilution by expansion.  Water waves sure don’t work that way, thank Heavens, or we’d be tsunami’d several times a day by earthquakes occurring near some ocean somewhere.

Feynman diagramHere we have a Feynman diagram, named for the Nobel-winning (1965) physicist who invented it and much else.  The diagram plots out the transaction we just discussed.  Not a conventional x-y plot, it shows Space, Time and particles.  To the left, that far-away electron emits a photon signified by the yellow wiggly line.  The photon has momentum so the electron must recoil away from it.

The photon proceeds on its million-lightyear journey across the diagram.  When it encounters that electron in your eye, the photon is immediately and completely converted to electron energy and momentum.

Here’s the thing.  This megayear Feynman diagram and the numbers behind it are identical to what you’d draw for the same kind of yellow-light electron-photon-electron interaction but across just a one-millimeter gap.

It’s an essential part of the quantum formalism — the amount of energy in a given transition is independent of the mechanical details (what the electrons were doing when the photon was emitted/absorbed, the photon’s route and trip time, which other atoms are in either neighborhood, etc.).  All that matters is the system’s starting and ending states.  (In fact, some complicated but legitimate Feynman diagrams let intermediate particles travel faster than lightspeed if they disappear before the process completes.  Hint.)

Because they don’t share a common history our nebular and retinal electrons are not entangled by the usual definition.  Nonetheless, like entanglement this transaction has Action-At-A-Distance stickers all over it.  First, and this was Einstein’s objection, the entire wave function disappears from everywhere in the Universe the instant its energy is delivered to a specific location.  Second, the Feynman calculation describes a time-independent, distance-independent connection between two permanently isolated particles.  Kinda romantic, maybe, but it’d be a boring movie plot.

As Einstein maintained, quantum mechanics is inherently non-local.  In QM change at one location is instantaneously reflected in change elsewhere as if two remote thingies are parts of one thingy whose left hand always knows what its right hand is doing.

Bohr didn’t care but Einstein did because relativity theory is based on geometry which is all about location. In relativity, change here can influence what happens there only by way of light or gravitational waves that travel at lightspeed.

In his book Spooky Action At A Distance, George Musser describes several non-quantum examples of non-locality.  In each case, there’s no signal transmission but somehow there’s a remote status change anyway.  We don’t (yet) know a good mechanism for making that happen.

It all suggests two speed limits, one for light and matter and the other for Einstein’s “deeper reality” beneath quantum mechanics.

~~ Rich Olcott

Is there stuff behind the stats?

dragon plate 3It would have been awesome to watch Dragon Princes in battle (from a safe hiding place), but I’d almost rather have witnessed “The Tussles in Brussels,” the two most prominent confrontations between Albert Einstein and Niels Bohr.

The Tussles would be the Fifth (1927) and Seventh (1933) Solvay Conferences.  Each conference was to center on a particular Quantum Mechanics application (“Electrons and Photons” and “The Atomic Nucleus,” respectively).  However, the Einstein-Bohr discussions went right to the fundamentals — exactly what does a QM calculation tell us?

Einstein’s strength was in his physical intuition.  By all accounts he was a good mathematician but not a great one.  However, he was very good indeed at identifying important problems and guiding excellent mathematicians as he and they attacked those problems together.

Einstein 187Like Newton, Einstein was a particle guy.  He based his famous thought experiments on what his intuition told him about how particles would behave in a given situation.  That intuition and that orientation led him to paradoxes such as entanglement, the EPR Paradox, and the instantaneously collapsing spherical lightwave we discussed earlier.  Einstein was convinced that the particles QM workers think about (photons, electrons, etc.) must in fact be manifestations of some deeper, more fine-grained reality.

bohr 187Bohr was six years younger than Einstein.  Both Bohr and Einstein had attained Directorship of an Institute at age 35, but Bohr’s has his name on it.  He started out as a particle guy — his first splash was a trio of papers that treated the hydrogen atom like a one-planet solar system.  But that model ran into serious difficulties for many-electron atoms so Bohr switched his allegiance from particles to Schrödinger’s wave theory.  Solve a Schrödinger equation and you can calculate statistics like average value and estimated spread around the average for a given property (position, momentum, spin, etc).

wittgenstein 187Here’s where Ludwig Wittgenstein may have come into the picture.  Wittgenstein is famous for his telegraphically opaque writing style and for the fact that he spent much of his later life disagreeing with his earlier writings.  His 1921 book, Tractatus Logico-Philosophicus (in German despite the Latin title) was a primary impetus to the Logical Positivist school of philosophy.  I’m stripping out much detail here, but the book’s long-lasting impact on QM may have come from its Proposition 7: Whereof one cannot speak, thereof one must be silent.

I suspect that Bohr was deeply influenced by the LP movement, which was all the rage in the mid-1920s while he was developing the Copenhagen Interpretation of QM.

An enormous literature, including quite a lot of twaddle, has grown up around the question, “Once you’ve derived the Schrödinger wave function for a given system, how do you interpret what you have?”  Bohr’s Copenhagen Interpretation was that the function can only describe relative probabilities for the results of a measurement.  It might tell you, for instance, that there’s a 50% chance that a particle will show up between here and here but only a 5% chance of finding it beyond there.

Following Logical Positivism all the way to the bank, Bohr denounced as nonsensical or even dangerously misleading any attachment of further meaning to a QM result.  He went so far as to deny the very existence of a particle prior to a measurement that detects it.  That’s serious Proposition 7 there.

I’ve read several accounts of the Solvay Conference debates between Einstein and Bohr.  All of them agree that the conversation was inconclusive but decisive.  Einstein steadfastly maintained that QM could not be a complete description of reality whilst Bohr refused to even consider anything other than inscrutable randomness beneath the statistics.  The audience consensus went to Bohr.

None of the accounts, even the very complete one that I found in George Musser’s book Spooky Action at A Distance, provide a satisfactory explanation for why Bohr’s interpretation dominates today.  Einstein described multiple situations where QM’s logic appeared to contradict itself or firmly established experimental results.  However, at each challenge Bohr deflected the argument from Einstein’s central point to argue a subsidiary issue such as whether Einstein was denying the Heisenberg Uncertainty Principle.

Albert still stood at the end of the bouts, but Niels got the spectators’ decision on points.  Did the ref make the difference?

~~ Rich Olcott

Gin And The Art of Quantum Mechanics

“Fancy a card game, Johnny?”
“Sure, Jennie, deal me in.  Wot’re we playin’?”
“Gin rummy sound good?”


Great idea, and it fits right in with our current Entanglement theme.  The aspect of Entanglement that so bothered Einstein, “spooky action at a distance,” can be just as spooky close-up.  Check out this magic example — go ahead, it’s a fun trick to figure out.

Spooky, hey?  And it all has to do with cards being two-dimensional.  I know, as objects they’ve got three dimensions same as anyone (four, if you count time), but functionally they have only two dimensions — rank and suit.gin rummy hand

When you’re looking at a gin rummy hand you need to consider each dimension separately.  The queens in this hand form a set — three cards of the same rank.  So do the three nines.  In the suit dimension, the 4-5-6-7 run is a sequence of ranks all in the same suit.Gin rummy chart

A physicist might say that evaluating a gin rummy hand is a separable problem, because you can consider each dimension on its own. <Hmm … three queens, that’s a set, and three nines, another set.  The rest are hearts.  Hey, the hearts are in sequence, woo-hoo!> 

“Gin!”

If you chart the hand, the run and sets and their separated dimensions show up clearly even if you don’t know cards.

A standard strategy for working a complex physics problem is to look for a way to split one kind of motion out from what else is going on.  If the whole shebang is moving in the z-direction, you can address  the z-positions, z-velocities and z-forces as an isolated sub-problem and treat the x and y stuff separately.  Then, if everything is rotating in the xy plane you may be able to separate the angular motion from the in-and-out (radial) motion.

But sometimes things don’t break out so readily.  One nasty example would be several massive stars flying toward each other at odd angles as they all dive into a black hole.  Each of the stars is moving in the black hole’s weirdly twisted space, but it’s also tugged at by every other star.  An astrophysicist would call the problem non-separable and probably try simulating it in a computer instead of setting up a series of ugly calculus problems.Trick chart

The card trick video uses a little sleight-of-eye to fake a non-separable situation.  Here’s the chart, with green dots for the original set of cards and purple dots for the final hand after “I’ve removed the card you thought of.”  The kings are different, and so are the queens and jacks.  As you see, the reason the trick works is that the performer removed all the cards from the original hand.

The goal of the illusion is to confuse you by muddling ranks with suits.  What had been a king of diamonds in the first position became a king of spades, whereas the other king became a queen.  You were left with an entangled perception of each card’s two dimensions.

In quantum mechanics that kind of entanglement crops up any time you’ve got two particles with a common history.  It’s built into the math — the two particles evolve together and the model gives you no way to tell which is which.

Suppose for instance that an electron pair has zero net spin  (spin direction is a dimension in QM like suit is a dimension in cards).  If the electron going to the left is spinning clockwise, the other one must be spinning counterclockwise.  Or the clockwise one may be the one going to the right — we just can’t tell from the math which is which until we test one of them.  The single test settles the matter for both.

Einstein didn’t like that ambiguity.  His intuition told him that QM’s statistics only summarize deeper happenings.  Bohr opposed that idea, holding that QM tells us all we can know about a system and that it’s nonsense to even speak of properties that cannot be measured.  Einstein called the deeper phenomena “elements of reality” though they’re currently referred to as “hidden variables.”  Bohr won the battle but maybe not the war — Einstein had such good intuition.

~~ Rich Olcott