Atheistforums
Science Section => Science General Discussion => Physics & Cosmology => Topic started by: Unbeliever on January 04, 2018, 07:40:25 PM

This is just really neat! I wonder what y'all think about it:
https://www.youtube.com/watch?v=WIyTZDHuarQ

Quantum mechanics, as a theory (not the phenomena, they are as old as the universe) started with Max Planck. He was asked to research how to make that new invention, the incandescent light bulb, more efficient. Edison either did or didn't invent that ... but most of us have seen one. The light coming from a light bulb, is the most obvious example of quantum mechanics visible to ordinary people.

I don't know enough about quantum mechanics to think about what it looks like. I always pictured particles streaking through a cloud chamber, but leaving short paths from when they disappear from existence. I assume that at a university, there would be something like a seminar where advanced students sit and speculate philosophically on what might be happening at that level.
I don't want to push this thread too far off track, but there doesn't seem to be much actual information about the subject. At least I don't encounter it in articles. Outside of this video, I haven't heard anyone try to explain much about quantum mechanics. It's treated academically and in science fiction more like a device to denote the speaker's high degree of intelligence, but it's seldom explained. It's referred to like someone engaged in name dropping. Just randomly insert the words "quantum physics" or "Heisenberg" in your dialog, and the listener is subconsciously conditioned to believe anything the speaker tells him, but not expected to understand a bit of it, because well, the speaker is really smart and the listener is just a dufus.
The theory of relativity can be explained quite simply and straight forward enough so that it can be understood in grammar school. Theories are not that difficult unless you want to linger on the mathematical equations. Quantum mechanics doesn't seem to be well enough understood that anyone has been able to simplify it enough to explain it, or for that matter, to have come up with an elegant equation. At one time, the theory of relativity held that kind of status. A correspondent from he LA Times who once interviewed Einstein, inaccurately reported that only three people in the world could understand relativity. But Since then, it has been explained simply so that most anyone can understand it. I keep thinking quantum mechanics is currently at a similar stage as where relativity once was, a stage where you are encouraged not to think about it, but to leave the heavy lifting to the genius types.

Einstein said, that you don't understand something, unless you can explain it to a six year old. Unfortunately Quantum Mechanics hasn't found any six year old smart enough yet ;)
On the video, I like it (and he is correct, this is a model of a quantum system (like sticks and balls is a solar system) not an actual quantum system). An incandescent light bulb is a quantum system (and so much for the Equipartition Law ... it doesn't work with an incandescent light bulb ... because the noncontinuous aspect of that phenomena, prevents it from being valid). This is expressed in Boltzmann statistics (classical) vs Fermi statistics and Bose statistics (both quantum). HS math is enough to understand models displaying each of these statistics.
Technically he speaks of "pilot waves" but that is nonstandard QM, developed originally by DeBroglie, which was the immediate predecessor to "wave mechanics" of Schroedinger.
https://en.wikipedia.org/wiki/Pilot_wave ... it applied to nonrelativisitc QM in particular but became obsolete with Heisenberg's "matrix mechanics", and the relativization of classical QM by Dirac, Feynman et al. But people today are still trying to bring it back ... because we love to equate phenomena to mechanical things we can see/understand (hence mechanical models of the luminiferous Ether overturned by Relativity). Feynman said however, that anyone claiming to understand QM, didn't. Or maybe he as just being Socrates.
http://hyperphysics.phyastr.gsu.edu/hbase/hph.html
This is the best undergraduate physics web page.
http://hyperphysics.phyastr.gsu.edu/hbase/quantum/statcn.html#c1
This subpage, clearly explains, to me, how quantum statistics works. I was able to reproduce the arguments, when I was studying QM thru Stanford (online) 2.5 years ago (studying quantum computing).
It is still a damn mystery, at least to megafauna like us humans, that an individual electron, can behave statistically, even if no other electron is present. The idea of a trajectory, like a moving car, is simply a megascopic simplification (if you accept QM).

I'm wondering if a quantum particle, such as an electron, can have a "worldline" given that it is not localized, but "spread out" so that it has no definite location before it's measured.

I'm wondering if a quantum particle, such as an electron, can have a "worldline" given that it is not localized, but "spread out" so that it has no definite location before it's measured.
With Relativity, your spacetime coordinates are fuzzed out differently than in QM. That is why Classical QM is relatively understandable (no Relativity to further fuzzy that worldline) and Relativistic QM is a bitch. Dirac invented it, and couldn't believe it or understand it himself at first (he did it as a formal exercise, not because of any physical intuition) because one conclusion was antimatter! ... physical intuition is what Einstein did, he worked out a physical intuition, saw contradictions (early modern EM theory) and beat the illogic out of it, like Sherlock Holmes ... that if we have eliminated the possible, and found no answer, then we have to accept that the impossible is true (your rest mass varies relative to the speed of the person measuring it). I don't have a problem with Classical QM, but there isn't a lot you can do with Relativistic QM, because it doesn't have closed solutions (like Classical Relativity and nonRelativity QM), instead you have to use slowly converging series expansions of functions (basically an equation with a nonfinite number of nonzero terms). A closed solution is simply an infinite series of functions, where all but a finite number of terms are zero ;)
https://www.youtube.com/watch?v=ZacggH9wB7Y
Notice, the DeBroglie approach got zero votes
Trying to follow the argument, leads to absurdities. If you get different absurdities depending on which interpretation you use (aka it isn't objective, or there would be one answer, no matter what interpretation you use). So the problem of Schrodinger's Cat vs Many Worlds. But a logician would say, that is proof of a prior mistake in reasoning. So maybe we can forget about logic? Fuzzy Logic is an attempt to use nondiscrete states (not even multiple logic states, but continuous). One error is Pythagoras, and another is his greatest follower, Plato. The world isn't number (discrete) it is continuous (different cardinal numbers). We extended the notion of number, to include continuous variables, but that isn't what Pythagoras was talking about. For him, the discrete numbers are real, and continuous valued are unreal ... leading to Plato, where the numbers are generalized to the World of Forms, and the continuous values are considered unreal. Exactly opposite of the case.

Einstein said, that you don't understand something, unless you can explain it to a six year old. Unfortunately Quantum Mechanics hasn't found any six year old smart enough yet ;)
What would be the purpose of explaining quantum mechanics to a six year old? To punish him? To bore him to death? Anyway, by the time he was 20, and in college, he would realize much of what you told him was incorrect.

What would be the purpose of explaining quantum mechanics to a six year old? To punish him? To bore him to death? Anyway, by the time he was 20, and in college, he would realize much of what you told him was incorrect.
Twenty year olds, do know it all. The purpose of explaining QM to a six year old, isn't for the six year old ... but for the one doing the explanation. This is why QM is still thuzzy finking. We haven't found that special six year old yet ;)

It's an excellent visualization, and provides the best commonsense explanation for the twoslit experiment I've seen yet (assuming you accept pilot wave theory). But it is, of course a model and therefore a simplification. I'd say that this is what QM kind of looks like.

Notice, the DeBroglie approach got zero votes
Physics isn't done by voting, it isn't a democratic process.

Physics isn't done by voting, it isn't a democratic process.
When two or more explanations have the same experimental result ... then people vote with their feet. There was Feynman, there was Schwinger and there was Tomonaga. Not even Pilot Waves. Everyone voted with their feet ... to Feynman, not because his results were different, but his method was easier to comprehend. Whether Pilot Waves is true or not, remains open. In fact, I don't consider science to the true or false ... just useful more or less. Newtonian mechanics is the most useful, and is used 100 times per day more than Relativity mechanics ... so people vote with their feet that way, even though the predictions are different, they aren't different enough to make a difference in most cases.

For the experimentallyminded, here's how to build your own quantum oil drop rig (https://staticcontent.springer.com/esm/art%3A10.1007%2Fs1265001603835/MediaObjects/12650_2016_383_MOESM6_ESM.pdf).