Quantum

Discussion of the nature of Ultimate Reality and the path to Enlightenment.
Dave Toast
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Post by Dave Toast »

Interestingly, in the last few months, new experimental data has come to light which might prove to be a nail in the coffin of both the Copenhagen AND Many Worlds interpretations. This is because the data seems to violate them both, whilst confirming the Transactional interpretation. This interpretation posits that quantum events propagate influences not only forwards in time but also backwards.

This means that determinism comes straight back into the picture - no more paradoxes and the attendant mysticism. Here's where it gets really interesting because this interpretation relies upon the literal physical reality of nonlocality, both in space and time (in both directions). Put another way, all events are instantaneously and intrinsically connected in space, and both forwards AND backwards in time.

So, under Copenhagen, an experimenter testing whether 14 billion year old light from stars exhibits either particle or wave behaviour was seen to be determining (or deciding) whether the light was actually emitted as a particle or a wave, all that time ago. Under Transactional, instead of the experimenter 'deciding', they are instantaneously communicating their mode of measurement 14 billion years back in time across 14 billion light years of space.

All very causal.
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David Quinn
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Post by David Quinn »

I assume this doesn't contravene the idea that nothing can travel faster than the speed of light? I can't imagine scientists are about to discard that traditional assumption, so they would have to invoke the concept of higher dimensions or something like that, I guess.

Also, the idea of causing events backwards in time is nonsensical to me, as it violates the very meaning of these terms. So if such a thing appears to be happening, I dare say it is an illusion generated by our own limited perspective.

-
Dave Toast
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Post by Dave Toast »

Nonlocality does violate the supposed universal speed limit. Scientists aren't generally pleased with nonlocality. But it's been proven that spatially separate particles can behave as though there is an instantaneous link between them. Make of it what you will.

I'm not really thinking of it as backwards causality, going off what I know about it. I'm thinking more of the iron blockish nature of a wholly determined system. Things could not be any other way than they are, things will not be any other way than they will be, and things could not have been any other way than they were. Communicating causality backwards in time is just an easy way of conceptualising the additional instantaneous interconnectedness this theory would have us understand as operating at all possible levels, everywhere and everywhen, simultaneously.
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Post by Kevin Solway »

Dave Toast wrote:Like you say, virtually all the energy is removed from a bunch of squashed together atoms by cooling them to almost absolute zero. Because we can now know the energy state (and therefore the momentum) of all these atoms very precisely, we can no longer know their position (the conjugate variable of momentum) very precisely at all.
Yet we know where all the atoms are, or whatever they have become, to a matter of micrometers.

I would call that a fairly precise measurement, given what we are dealing with, since I would think that the lower their energy, the harder it is to measure them.
If it were the case that this was just a limitation of our perception, then we'd expect that the atoms' positions are actually definite but we just can't percieve them definitively, and that therefore, the atoms would carry on acting as though their position were definite. But that's not the case
How can we measure whether such atoms are acting as though their individual positions were definite, if we lose the ability to see their individual definite effects? If we were able to see such effects of atoms in definite positions, that would be the same as seeing the definite positions of the atoms.

To themselves the atoms might be acting as though their positions were definite - for example, the atoms might not be bumping into or overlapping one another, and their electron shells may still be repelling one another - even though we have lost the ability to detect this?

It seems to me that it would be impossible to prove otherwise, but science must go with what it observes, rather than what is.

Can you provide a clarification, or another example?
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Nonlocality

Post by Kevin Solway »

Dave Toast wrote:I'm not really thinking of it as backwards causality, going off what I know about it. I'm thinking more of the iron blockish nature of a wholly determined system. Things could not be any other way than they are, things will not be any other way than they will be, and things could not have been any other way than they were. Communicating causality backwards in time is just an easy way of conceptualising the additional instantaneous interconnectedness this theory would have us understand as operating at all possible levels, everywhere and everywhen, simultaneously.
Yes, in my view there doesn't need to be any "communication" as such, since the two things communicating are not two separate things, but are part of the same "iron block" as you put it.
Last edited by Kevin Solway on Tue Aug 16, 2005 4:21 pm, edited 1 time in total.
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Jamesh
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Post by Jamesh »

The Uncertainty principle is for 'real'. It decribes a physical actuality, not a limitation of perception.

Rubbish. It is meaningless to philosophy. It is only meaningful to physicists, because it is about accuracy and predictibility, which by default means it is about appearances.
Dave Toast
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Post by Dave Toast »

Hence the inverted commas around the word 'real' and the careful use of the word 'physical', even though the distinction you're making is taken as read around here.

Try to be a little less condescending in making your initial posts and points, such as they are.
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DHodges
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Bose-Einstein Condensation

Post by DHodges »

Dave Toast wrote:Because the Exclusion principle only applies to Fermions. Bose-Einstein condensates are made with, you guessed it, Bosons.
From what I was reading (which was, admittedly, the cartoon version for fourth graders), they were using atoms of rubidium.

Does an atom act like a boson here? I was thinking it would act like a fermion, since it is composed of fermions.
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Matt Gregory
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Bell test

Post by Matt Gregory »

Well, I'm trying to understand this EPR paradox and the Bell test experiments, but they don't explain very much about the test. Why do they shoot the particles in opposite directions? Why not the same direction? Why do they think that the apparatus that produces the particles has no effect on the particles?
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Post by Leyla Shen »

Bosons and fermions are subatomic particles -- unless they've changed the rules again. Seems like someone's trying to turn force into matter.

Dave Toast! Where are you??
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Post by Leyla Shen »

You're doing better than I am then, Matt. I'm still trying to work out how a massless particle has "spin." Blimey.
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DHodges
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Re: Bell test

Post by DHodges »

Matt Gregory wrote:Well, I'm trying to understand this EPR paradox and the Bell test experiments, but they don't explain very much about the test. Why do they shoot the particles in opposite directions? Why not the same direction? Why do they think that the apparatus that produces the particles has no effect on the particles?
The direction the particles go is of no importance, other than that they go to separate detectors.

It would help to know what you are reading. Have you looked at the wikipedia articles?
http://en.wikipedia.org/wiki/EPR_paradox
http://en.wikipedia.org/wiki/Bell%27s_theorem
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Matt Gregory
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Re: Bell test

Post by Matt Gregory »

DHodges wrote:
Matt Gregory wrote:Well, I'm trying to understand this EPR paradox and the Bell test experiments, but they don't explain very much about the test. Why do they shoot the particles in opposite directions? Why not the same direction? Why do they think that the apparatus that produces the particles has no effect on the particles?
The direction the particles go is of no importance, other than that they go to separate detectors.

It would help to know what you are reading. Have you looked at the wikipedia articles?
http://en.wikipedia.org/wiki/EPR_paradox
http://en.wikipedia.org/wiki/Bell%27s_theorem
Sorry, I thought I said that, I must have erased it. Yeah, it was Wikipedia.

I don't even think it matters what the Bell experiment is, I think it's just smoke and mirrors. You can't conclude that there are no hidden variables no matter what empirical experiment you do, can you? I mean, that's a philosophical conclusion.
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Matt Gregory
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Post by Matt Gregory »

Leyla Shen wrote:You're doing better than I am then, Matt. I'm still trying to work out how a massless particle has "spin." Blimey.
It's very confusing. Mostly because the writing on it sucks. Like this article:

http://en.wikipedia.org/wiki/Superposition_principle

What they're talking about is simple, but they make it sound like something really complicated. All they're saying is that the amplitudes of two overlapping waves are added together. It's just common sense, really.

Science should be banned.
Dave Toast
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Post by Dave Toast »

ksolway wrote:
Dave Toast wrote:Like you say, virtually all the energy is removed from a bunch of squashed together atoms by cooling them to almost absolute zero. Because we can now know the energy state (and therefore the momentum) of all these atoms very precisely, we can no longer know their position (the conjugate variable of momentum) very precisely at all.
Yet we know where all the atoms are, or whatever they have become, to a matter of micrometers.

I would call that a fairly precise measurement, given what we are dealing with, since I would think that the lower their energy, the harder it is to measure them.
Precision is obviously relative, so you could say we can measure them 'fairly precisely' but then fairly precise isn't very precise. It's fairly precise to say that 7 lies between 1 and 10 but not as precise as saying it lies between 6 and 8.
ksolway wrote:
Dave Toast wrote:If it were the case that this was just a limitation of our perception, then we'd expect that the atoms' positions are actually definite but we just can't percieve them definitively, and that therefore, the atoms would carry on acting as though their position were definite. But that's not the case
How can we measure whether such atoms are acting as though their individual positions were definite, if we lose the ability to see their individual definite effects?
Basically, by theorising how they would act if their position were not definite and then testing this theory against observation.

We don't lose the ability to do this as we can still observe the effects and theorise as to whether they are those of individual definite position, or not. All this is according, of course, to what we know.
ksolway wrote:If we were able to see such effects of atoms in definite positions, that would be the same as seeing the definite positions of the atoms.
I can see what you're getting at but you don't need to measure the wind to to know that there is wind if the leaf is moving, according to what we know of leaves and wind.
ksolway wrote:To themselves the atoms might be acting as though their positions were definite - for example, the atoms might not be bumping into or overlapping one another, and their electron shells may still be repelling one another - even though we have lost the ability to detect this?
That could well be the case. But when we theorise a definite observable behaviour for groups of atoms acting as though without definite position, according to what we know of how they do act with definite position, and then we observe this behaviour under experiment; we have a scientific theory which predicts, describes and explains the mechanics of this behaviour.
ksolway wrote:It seems to me that it would be impossible to prove otherwise, but science must go with what it observes, rather than what is.
Well quite. But that is the context of 'real' that we were talking about, i.e. our scientific understanding of physical reality.
Dave Toast
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Re: Bose-Einstein Condensation

Post by Dave Toast »

DHodges wrote:
Dave Toast wrote:Because the Exclusion principle only applies to Fermions. Bose-Einstein condensates are made with, you guessed it, Bosons.
From what I was reading (which was, admittedly, the cartoon version for fourth graders), they were using atoms of rubidium.

Does an atom act like a boson here? I was thinking it would act like a fermion, since it is composed of fermions.
Depends on what isotope of Rubidium you use. Rb-85 is a boson, the rest are fermions.
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Post by Dave Toast »

Leyla Shen wrote:Bosons and fermions are subatomic particles -- unless they've changed the rules again. Seems like someone's trying to turn force into matter.
Bosons are not only the force carriers. Protons and nuclei, which are 'matter' particles, can also be bosons.
Leyla Shen wrote:I'm still trying to work out how a massless particle has "spin." Blimey.
We've spoken about this before though. The spin of quantum mechanics is not like the spin of a spinning top or an asteroid. It has no direct analogy in the macro world.
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Post by Leyla Shen »

Yes, you are right -- we have. Unfortunately, it has also been that long since I've seriously revisited the subject.

Having briefly reviewed it anew, I realise my problem is not so much with the notion of (particle) spin any more as it is with abstract mathematics. I shall have to tie up my children for several months. I don't think I'm likely to master it as a snack between the main courses in my life.
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DHodges
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Post by DHodges »

Dave Toast wrote:Bosons are not only the force carriers. Protons and nuclei, which are 'matter' particles, can also be bosons.
I did not realize that. I thought of 'normal' matter as being fermions. It seems like this might have implications beyond the BEC stuff. I'll have to think about it.
The spin of quantum mechanics is not like the spin of a spinning top or an asteroid.
Yeah, maybe 'spin' was a bad word choice. They might have been better to call it something like 'charm' like they did with quarks. Calling it 'spin' makes you think you should have an intuitive grasp of how it works.
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Diebert van Rhijn
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Post by Diebert van Rhijn »

<insertion of some relativity and humor>

One could wonder if the models and interpretations of quantum physics are perhaps revealing more of our own thought processes or faith in our 'objectivity' than it's really helping describing Reality.

The following article might describe one of the consequences of this: that we are discovering how our daily world behaves the same as our theories describe fundamental particles!

Human relationships behave like atomic nuclei, says physicist
At the root of the system, says Mr Ecob, is the similarity between the probability of the nucleus of an atom decaying and that of a couple breaking up.

The decay of a nucleus is described in terms of "transit states": the series of change it has been through to get to its current situation.

The probability of someone having been in two relationships, for example, is the same as that of a nucleus decaying twice.
<end insertion>
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Matt Gregory
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Post by Matt Gregory »

If it could stimulate us into understanding ourselves better that would be a more worthwhile product of quantum mechanics than using it to create some new gadget that we can strap on our wrist and receive instant message with or whatever.

That theory of Ecob's is pretty damn silly, though. I can't believe writing a computer program that supports some pet theory is considered "research".

Science should be banned.
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Matt Gregory
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Post by Matt Gregory »

I don't know if anyone noticed, but right after I made that post, the database on the other end decided to take a snooze and I couldn't access the board (not sure how long it was down, though, since I went to bed). That's another great example of why science should be banned. Although I'm joking when I say I that, I do think people get carried away with new research. We acquire results and create technology so fast that we can't understand the science behind it, so we're slowly losing control of it. By the time we figure out how to keep a PC running, we'll have advances in nanotechnology, quantum computing, genetics, medicine, and so on and so on to deal with.

We don't take any time to assimilate our research to try and come to an understanding of it as a species, we just press on with the fact gathering hoping that this gathering in itself will give us understanding, but it will come to a point where we will judge the success of a technology by how few people it kills. That will be the research. It's already come to that point to some extent. If scientific knowledge isn't accessible to the wider public, then there are no checks on the scientists who publish the results. Corruption exists in science as much as it does in politics. All it takes are a few outspoken believers who have no idea what they are talking about to create a huge swarm of the same.

Back in the old days people had decades to think about a scientific advance before a new one came along, so when it did, people already had a good idea of what it meant. We don't have that luxury nowadays.
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Post by Sapius »

Sevens: Kevin, Do you believe the reports of yogis, shamans, buddhas and sorcerers being able to develop bi-location siddhis?

Kevin: I don't beleive this has ever been demonstrated.
It has been witnessed, but not demonstrated as such, but the fact is that you have not witnessed it, and you will never believe unless it has been demonstrated to you, hence no point in discussing. If one wants to witness it, he should have enough interest and time to trace and locate such a person, and even then, there is no guaranty of a “show”. May be they are simply not interested in an illusory world and hence live a very reclusive life, and they do not do it to simply demonstrate or prove anything to anyone. It is absolutely personal to them. Basically, I think one needs to be in the right place at the right time, and then, only then, one might get lucky.

I can simply say just one thing, keep an open mind, we really do not know all that much about existence as yet, Ultimate Truths aside.

David wrote:
There is also the question of why a sage would want to bifuricate into two positions in the first place. Does he want to join the circus or something?
I don’t get it. Does anyone ever really ‘wants to’? Are you implying free-will here, David? Is it only you that is guided by nature, and cause and effect? Are only your experiences valid because someone else confirms by agreeing to it?

To quote Dave Toast:
"Interestingly, in the last few months, new experimental data has come to light……"

…and that too is not the end of it.
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