Opinions on Physics - Puzzles, mysteries, that sort...

How does science work? And what's all this about quantum mechanics?

Moderators: AMod, iMod

converge
Posts: 113
Joined: Thu Feb 03, 2011 1:18 am

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by converge » Tue Mar 15, 2011 10:31 pm

Hi Mike,

I'm not an expert in quantum physics but i know a bit about it. The main problem with the dice analogy is that it doesn't really show the core foundations of quantum theory. When you're shaking an actual die in your hand, you don't know which face is currently facing up, but it does have one particular face pointing up at any time. So it's not really a cloud of probabilities. It is in one distinct position at any particular time; you, personally, just don't know what that position is.

A "quantum" die, on the other hand, is actually physically in a state where it is simultaneously in every position at the same time; it is simultaneously showing 1, 2,... 6, on the top face, all at the same time. If you could see it, you would see it sort of like a long-exposure photograph of the die rolling around... it would be a blur of every position at once. It's not just spinning really fast though, it's just in every position at the same time. Quite unlike anything we ever experience in everyday life. If you then did something that required the die to be showing a particular face, like, touched it, it would collapse into one solid state.

That's the key idea with a probability cloud. A lot of people mistake it to mean that the electron is buzzing around in a particular way, and we just "don't know" where it is exactly, so we can only say where it might be and what the probability of it being there is. But that's not really what it means. A probability cloud means the electron actually is in every place within the cloud at once. Performing some action that causes us to pinpoint the electron doesn't just mean we "found" it, we actually caused it to be in that position by collapsing the cloud.

converge
Posts: 113
Joined: Thu Feb 03, 2011 1:18 am

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by converge » Tue Mar 15, 2011 10:43 pm

Mike Strand wrote: The experiment shows that the pattern differs depending on whether or not we observed each electron's path before it made a contribution to the pattern! It's as if watching them makes them "behave" as particles, or tiny bullets; otherwise they behave like wild and crazy wavelets. Could we find a way to "sneak" a look without "influencing" them?
Yes, this is basically it. But it's not just us looking at them that causes it. That's the more human-centric idea that a lot of new age quantum mysticism is about. (For example, the movie What The Bleep Do We Know). Scientists would say it's not the act of us observing it that causes the collapse, it's more like "Anything that requires the photon to need a specific position causes it to have a specific position". So when you set up the detectors on the sides, the photons "have" to be there in order for the universe to make sense, so they take on positions. When the detectors aren't there, the photons don't "have" to have a specific position because nothing large-scale is affected by that, so they don't. So the experiment would look the same even if no one were looking at it. There's no way to sneak a look because any possible action that would require it to have a position or velocity would cause it to have a position or velocity.

Whenever the particle "has" to have a certain state, that's when the waveform collapses. To be honest, I'm still a bit confused on how they determine exactly what constitutes a situation where waveform collapse has to happen.

User avatar
Cerveny
Posts: 573
Joined: Thu Mar 11, 2010 9:35 pm
Location: Czech Republic
Contact:

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Cerveny » Tue Mar 15, 2011 10:55 pm

The essence of Quantum Mechanics is based on the demand of no changing (of density) of state's probability during the measurement (better, during the interaction) ||fi^2||. Every interaction (measurement) fixes particular (possible) system's status to the history, glues new time sediment to the history...

Mike Strand
Posts: 406
Joined: Wed Jan 06, 2010 6:54 am
Location: USA

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Mike Strand » Wed Mar 16, 2011 1:44 am

Thanks, converge and Cerveny, for your intriguing comments. I point to converge's statement:
Whenever the particle "has" to have a certain state, that's when the waveform collapses. To be honest, I'm still a bit confused on how they determine exactly what constitutes a situation where waveform collapse has to happen.
I'm just as confused as you are, converge, and I also wonder: Has quantum theory been able to characterize the situations which require or entail waveform collapse?

My next question: Is there any conceivable way to observe the electron "passively" that would reveal its supposed non-collapsed probability-wave state? For until we can make such an observation, we're only assuming that the electron is everywhere in that "probability cloud" at once. It seems to me we are only hypothesizing that the electron, in essence, is truly a wavelet-like disturbance in space-time. I would still like to think, with Schroedinger himself, that his equations express a probability distribution, not a physical waveform.

In everyday life, during daylight, I can look at an elephant and perceive it passively. I'm not sending out any kind of a signal (am I?) to detect it, as I would apparently have to in the double slit experiment to observe an electron. The light from the sun reflecting from the elephant and into my eyes causes me to see it. Would anyone be willing to claim that the sunlight causes the waveform of the elephant to collapse, just so I can see it?

Now, let's try going from an elephant to an electron: Surely an electron is continuously interacting with bits or fields of energy other than the slit experiment's detection device. Would these background interactions keep the hypothetical electron waveform collapsed, or at least in a collapsed state much of the time? Could some way be found to passively capture these background interactions in order to "see" the electron? What would we see? A particle? A vibrating string? A wavelet?

Observation itself implies sub-atomic interactions, whether passively detected, or obtained through sending out signals from the observing equipment. How can we possibly distinguish the phenomenon of observation from what we're trying to observe? This could mean very high measurement error, of a nature and magnitude totally different from the error in measuring, say, the speed of a moving car.

Probability theory is the tool we use in an attempt to make sense of our fuzzy and ambiguous "observations" of sub-atomic entities. And the probability equations themselves may not reflect perfectly what's going on, because of hidden factors. Probability theory is limited because of hidden factors even in its application to larger phenomena, like waiting time in queues.

We at least have evidence that electrons exist. Given this, electrons are what they are, but we may not have much of a clue as to what they are. I'm just speculating that our measurements are fooling us into ideas and theories that appear to make these pesky entities appear almost magical, with "minds" of their own. Our attempts to compare them with either particles or waveforms may be inadequate models for describing any sub-atomic entity, like the old solar system model was for the atom.

In quantum physics, I'm speculating that we may be reaching beyond the limits of our human biological capacity to observe. In a way, quantum physics may be like the old geocentric theory of astronomy -- able to make predictions, but somehow missing the larger picture. For example, the geocentric theory could predict -- or at least describe and quantify -- the precession of planetary orbits, but it seemed weird in that theory that the planets would actually behave that way. This motion is only apparent and not weird at all under the heliocentric view. In contrast, it may turn out that we are incapable of going beyond quantum theory to see the larger picture, because of inherent limitations in our ability to observe the world of sub-atomic entities.

For example (exaggerating, perhaps, to make a point), in the double-slit experiment, do we really know what an electron is, and if not, how do we know when or whether we're projecting them at the double-slit plate, let alone one at a time? Or even that we are observing an electron when we think we are? If we are measuring a mysterious combination or interaction of two sets of phenomena - one associated with our observation tools and the other with what we are trying to observe - how do we separate the two aspects in the resulting "measurements"?

Mike Strand
Posts: 406
Joined: Wed Jan 06, 2010 6:54 am
Location: USA

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Mike Strand » Wed Mar 16, 2011 5:13 am

Question: Is the observational apparatus in the double-slit experiment, used to detect which slit the electron goes through, a "passive" device, or does it put out some kind of energy or other signal, which interacts with the electron, in order to make this observation? I assumed in my last post that it was the latter, and I may be off base.

Another question: Could we somehow use an apparatus to simply send out energy to interact with the electron as it approaches the two-slit plate, without actually checking on what happens -- that is, ignore the informational output of the apparatus, or suppress it? Wouldn't this have the effect of collapsing the electron wavelets into particles, thus producing the two-band pattern? Or, because we really didn't observe the electron before it gets to the plate, but only the resulting pattern, would we get the wave-related interference pattern?

This is trying to get at what "observation" means, or, getting back to converge's remark, what has to happen for the waveform to collapse. Isn't there enough background stuff impinging on the electrons to get them to "collapse" to particles, even if we don't set up any kind of apparatus? Can an electron "tell the difference" between background interference with its journey, and interference from our observational equipment?
Last edited by Mike Strand on Wed Mar 16, 2011 5:38 am, edited 1 time in total.

Izzywizzy
Posts: 155
Joined: Fri Feb 18, 2011 3:52 pm

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Izzywizzy » Wed Mar 16, 2011 5:32 am

hi Mike the double slit experiment has been discussed by me on my "what is consciousness " post
Interestingly the double slit experiment shows that by simply observing them we can collapse the wave function of electrons
It seems electron wave responds to our minds over its matter

http://www.youtube.com/watch?v=DfPeprQ7oGc
there is more to it than this link but its a start..for instance light cant be both wave and particles its an either or?..which loses quantum and goes to ether..which is discussed by me on my aether thread ie "what is ether"..if your hungry for answers look further than a science which can`t say one frome the other but makes them two and the same..ask why to asking why not

Mike Strand
Posts: 406
Joined: Wed Jan 06, 2010 6:54 am
Location: USA

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Mike Strand » Wed Mar 16, 2011 5:49 am

Thanks, izzywizzy, I'll check it out.

I can't help, though, sticking for the time being to the scientific approach, and critically examine our scientific techniques. The old geocentric picture of planetary orbital precession was counter-intuitive (weird), but this disappeared with the heliocentric picture -- more data and observations resulted in a better theory.

My concern is we can't get a better picture or theory than quantum theory, due to inherent limitations in our human ability, even with clever tools, to "observe" things at the atomic level and below: Especially if the act of human observation itself always involves sub-atomic phenomena which become entangled with the phenomena of the sub-atomic entity we are trying to observe. If this is the case, and since human observation appears to involve our "consciousness", whatever that is, then maybe we do need to learn more about the human psyche, as you appear to suggest.

Izzywizzy
Posts: 155
Joined: Fri Feb 18, 2011 3:52 pm

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Izzywizzy » Wed Mar 16, 2011 5:58 am

I certainly didn`t say otherwise mike ..i said ask the science that says not stick to its bias..aether is proven by science..but which science are you sticking to? the science that says quantum? was disproved 70 yrs ago to my knowledge..but call me a stickler for real science..you seem to think scinece means one thing one branch..it doesn`t and never has...no more than religion does..there are many branches of religion and science..please don`t think i am asking you not to be scientific..that is not the case..i insist you become more scientific..i am insisiting you take the scientific approach.

Mike Strand
Posts: 406
Joined: Wed Jan 06, 2010 6:54 am
Location: USA

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Mike Strand » Wed Mar 16, 2011 6:09 am

OK, izzywizzy. Maybe I should have said, let's see if, within the current field of physics and physical experiments involving sub-atomic particles, we can improve techniques -- of observing and analyzing the results.

Science itself is larger than this, in a sense. I view it as any method of inquiry involving human perceptions and observations, aided or not aided by tools, which can be repeated and verified publicly, and based upon which theories are developed which can be tested (verified or refuted) and changed if warranted by new information or better reasoning. It is a self-critical and self-correcting method of inquiry, and includes the work being done currently in physics, but also in other areas, like neuroscience.

Izzywizzy
Posts: 155
Joined: Fri Feb 18, 2011 3:52 pm

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Izzywizzy » Wed Mar 16, 2011 6:25 am

let me put it this way Mike
Do you question if relativity and quantum mechanics is an effective model that only seems to provide the maths to describe things, not actually the explanation? The maths for the Heisenberg Uncertainty Principle explains it mathematically but only if thats true ? it is maths to suit an observation, not really to explain it. I don`t think any theory can be correct unless it can be explained with and or without math.

Quantum physics and Special Relativity contradicts our life experiences.

Aether at least explains a fifth fundamental force better than quantum and special relativity does.
The idea Aether is charged particles (although not conventional charge )well have you seen a mathematical description of that? What charge are we talking about? If its not EM, weak, Strong, or gravitational, then it should be the fifth fundamental force.
describtion from a website
"...Aether (a fabric of quantum rotating magnetic field) is equally as important as the matter that resides within it. From here, we can derive a single force that gives birth to the Aether and maintains the existence of subatomic particles [I'll just put in here that there is a lot of mention of angular momentum and how that makes subatomic particles]. The theory implies the Aether has the qualities of reciprocal mass and charge in addition to the dimensions of length and time. Aether is also the source of curved geometry as expressed by Albert Einstein in his General Relativity Theory..."
any theory worth its salt should be able to be explained in laymans terms.

User avatar
Aetixintro
Posts: 319
Joined: Tue Jan 08, 2008 7:44 pm
Contact:

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Aetixintro » Wed Mar 16, 2011 6:45 am

Quantum physics and Special Relativity contradicts our life experiences.
I contest this! If they are properly described, they can't contradict our life experiences.

Mike Strand
Posts: 406
Joined: Wed Jan 06, 2010 6:54 am
Location: USA

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Mike Strand » Wed Mar 16, 2011 6:57 am

Thanks again, Izzywizzy! I certainly do question the ability of current scientific theories to explain, beyond mathematical description. But that's the case even with Newton's law of gravity -- what is it about two masses that cause them to "attract" each other over a large distance, seemingly instantaneously? Even in relativity theory, the analogy of mass bending space, like a marble on the surface of a membrane, is really only a geometric picture, and still doesn't tell us how or why mass can bend or distort space.

I also have to apologize to all readers of this thread -- I've been using "planetary orbital precession" as an example, but I really meant to say "retrograde motion of planets in their orbits". It's retrograde motion that looked weird in the geocentric view, and came to be seen only as an apparent motion, not weird at all, under the heliocentric view.

Finally, I have to confess my ignorance about ether (or aether) theory. I thought the idea of ether, as the medium through which light travels, went out with the Michelson-Morely experiment. But now I realize there has been more speculation among scientists (including Einstein himself) about something called Aether since then... pardon me while I try to bring myself up to date. I hope it might improve the ability of a layman like myself to understand things like gravity and quantum physics -- does it, Izzywizzy?

converge
Posts: 113
Joined: Thu Feb 03, 2011 1:18 am

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by converge » Wed Mar 16, 2011 6:13 pm

Mike Strand wrote: Finally, I have to confess my ignorance about ether (or aether) theory. I thought the idea of ether, as the medium through which light travels, went out with the Michelson-Morely experiment. But now I realize there has been more speculation among scientists (including Einstein himself) about something called Aether since then... pardon me while I try to bring myself up to date. I hope it might improve the ability of a layman like myself to understand things like gravity and quantum physics -- does it, Izzywizzy?
I'm sure izzy will be infuriated with me saying this, but you are right that Aether/Ether (they're just two spellings of the same thing) went out with the Michelson-Morley experiment. There isn't actually any speculation among modern scientists (nor Einstein; he was disproving Aether). There are, however, a lot of crackpot conspiracy websites that think that relativity and quantum physics must be a lie because they sound so strange, and a bunch of people trying to drag physics back to the medieval ages by insisting that there must be some explanation for all the weirdness using good old simple elementary physics. But there isn't. All the websites fail to really understand how QM and Relativity work, and use a lot of fancy words to make it sound like they are saying something scientific, but they're not. Classic physics is gone; the last eighty years of progress is not going to be undone no matter how many conspiracy websites pop up.

Mike Strand
Posts: 406
Joined: Wed Jan 06, 2010 6:54 am
Location: USA

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by Mike Strand » Wed Mar 16, 2011 7:40 pm

Converge, thanks for your input. But isn't it a little dangerous to claim that a theory, even QM, despite it's long life, will never be supplanted by a better one? Not that the last eighty years of progress will be undone -- only supplemented, by theory based on new evidence, new data, new thinking. It may not happen for a thousand years, due to the seeming brick wall of an inherent limitation in our ability to measure. Human progress in physics may even end with QM. But that is not to say a better theory is inconceivable and may be developed by a species of intelligent life of whom we will be a common ancestor. And the new theory may not look anything like either QM or so-called "classical" physics.

I agree that any replacement theory (if that should ever happen) will have to meet the rigorous standards of testability and challenge that are part of the scientific method. Newton's theories of motion stood for a long time before Einstein improved on them with new observations and thinking, as did the geocentric theory of the motions of stars and planets.

Think of the real line (the set of real numbers) in mathematics. No matter how small the interval between two selected numbers, there is a number between them. Any interval, no matter how small, can be subdivided into a million -- a billion -- even more, intervals. Could the granularity of quantum "reality" only be an artifact of our inability to measure smaller intervals? Just speculation, and personal caution based on my own reading of the history of scientific theories.

Taking the set of real numbers is overkill, to make this point. Just take the set of rational numbers -- those that can be expressed as the ratio of two integers. This set is countably infinite and a proper subset of the real numbers (uncountably infinite). And yet, for any interval defined by two rational numbers, however close together, there is a rational number between them. Intervals of arbitrary smallness can be obtained from using only the rational numbers. Is it too much to speculate that someday someone will be able to measure much smaller intervals in "space" than is now possible?

Jupiter's moons were discovered using a more powerful telescope than available up to then. Better power to discriminate. In the other direction, microscopes and other devices can measure the extremely small, down to the point of our best equipment. Cannot more powerful devices for discriminating even smaller intervals someday be developed?

converge
Posts: 113
Joined: Thu Feb 03, 2011 1:18 am

Re: Opinions on Physics - Puzzles, mysteries, that sort...

Post by converge » Wed Mar 16, 2011 9:12 pm

Mike Strand wrote:Converge, thanks for your input. But isn't it a little dangerous to claim that a theory, even QM, despite it's long life, will never be supplanted by a better one? Not that the last eighty years of progress will be undone -- only supplemented, by theory based on new evidence, new data, new thinking. It may not happen for a thousand years, due to the seeming brick wall of an inherent limitation in our ability to measure. Human progress in physics may even end with QM. But that is not to say a better theory is inconceivable and may be developed by a species of intelligent life of whom we will be a common ancestor. And the new theory may not look anything like either QM or so-called "classical" physics.
Oh yes, I definitely think we'll continue to discover more and more, but QM is definitely not "wrong" in the sense that aether supporters believe. Newtonian physics isn't really "wrong" either. It works perfectly well when dealing with normal sized objects in our everyday world. Newtonian physics stop working at a really small scale though, which is where QM comes in. And they stop working at a really large scale, which is where relativity comes in. When QM came around, it didn't prove that Newtonian physics are false; it didn't say "Ha! All along you thought that apples that break off a tree would fall to the earth, and in actuality they don't!" Discovering QM didn't mean that apples actually float away when they break off the branch. It just showed that the calculations are slightly different than what we expect. Aether supporters want relativity to be fundamentally "wrong", they expect that at some point someone will say "Ha! All along you thought that time moves slowly for fast moving objects, but you were wrong!" That will never be the case; it has been solidly proven to be true. even if we change the formulas slightly after discovering more detail, we are never going to discover that time dilation is fake, just like we will never discover that apples don't fall down when they are detached from the branch.
I agree that any replacement theory (if that should ever happen) will have to meet the rigorous standards of testability and challenge that are part of the scientific method. Newton's theories of motion stood for a long time before Einstein improved on them with new observations and thinking, as did the geocentric theory of the motions of stars and planets.
Yes, I agree, but the problem with Aether is that they refuse to believe the results of all the experiments in the last eighty years; they think that it's a conspiracy, and that there is no real evidence. Much like creationists insist there is no evidence for evolution, and Republicans insist there is no evidence for climate change, and that all of the supposed evidence for both is actually a big conspiracy.
Think of the real line (the set of real numbers) in mathematics. No matter how small the interval between two selected numbers, there is a number between them. Any interval, no matter how small, can be subdivided into a million -- a billion -- even more, intervals. Could the granularity of quantum "reality" only be an artifact of our inability to measure smaller intervals? Just speculation, and personal caution based on my own reading of the history of scientific theories.
I was just watching some youtube videos last night about "digital physics", which explores this idea, of how there must be an eventual "smallest unit" of distance or time (the Planck distance and time) in order for anything to actually work, and that this is apparently how the universe functions. That even though the equations behind it all are linear like the real numbers (with infinite divisibility), that it seems the universe itself is actually running in steps, like frames in a movie or video game, where each frame is computed using the underlying formulas.
Taking the set of real numbers is overkill, to make this point. Just take the set of rational numbers -- those that can be expressed as the ratio of two integers. This set is countably infinite and a proper subset of the real numbers (uncountably infinite). And yet, for any interval defined by two rational numbers, however close together, there is a rational number between them. Intervals of arbitrary smallness can be obtained from using only the rational numbers. Is it too much to speculate that someday someone will be able to measure much smaller intervals in "space" than is now possible?
It's possible, but currently it seems there is a fundamental limit on space and time (the Planck space and Planck time) where, beneath which, space and time have no meaning. It is not that we just don't have powerful enough microscopes to see it, it appears that it the universe is fundamentally "pixelated" like a computer screen no matter how much we zoom in, and that particles can only "jump" from one pixel to the next; they never move through the space between.
Jupiter's moons were discovered using a more powerful telescope than available up to then. Better power to discriminate. In the other direction, microscopes and other devices can measure the extremely small, down to the point of our best equipment. Cannot more powerful devices for discriminating even smaller intervals someday be developed?
Well, I'd never say never, especially since I'm still not that well-versed in QM, but there are differences between the two cases. When we couldn't see Jupiter's moons, it wasn't because we thought there was a fundamental property of the universe stopping us from seeing that far; we knew we could probably see that far, we just didn't know how to build a strong enough telescope. With QM, we have observed the universe on a very small scale and it appears that it is fundamentally working in discrete "steps"; the particle just pops from one pixel to the next. No matter how closely we look, it won't change the fact that the particle is not moving "through" the space in between. If there is anything to "see" in that zoomed in space between jumps, it won't be particles or energy as we normally think of them, it would be something else entirely.

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests