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#37449 - 02/14/11 08:53 PM General relativity on large scales.
Bill S. Offline
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General relativity, we are told, breaks down at the smallest scales, but does it necessarily hold good on a cosmic scale.

Non-local correlations can exist over cosmic distances and require collapse of the wave function to occur over such distances simultaneously with the measurement. At a minimum the notion of simultaneity requires a synchronous coordinate system for spacetime.

This does not sit well with relativity which militates against the concept of an absolute time frame.
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#37450 - 02/14/11 09:24 PM Re: General relativity on large scales. [Re: Bill S.]
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This is one of the weird things about quantum theory (QT). Quantum entanglement has been experimentally verified, so there is no question that it happens. There have been 3 suggested explanations for how it happens. None of the 3 is particularly probable, but experiments have been performed that invalidate all 3 individually. Last year an experiment was performed that invalidated 2 of them at the same time. But it is highly improbable that the remaining one is true, especially since it has been invalidated by itself. People are still working on it and hope to come up with an experiment that invalidates all 3 explanations at the same time.

In 1935 Albert Einstein, Podolsky, and Rosen wrote a paper (the EPR paper) about entanglement in which they explained it away using one of the 3 explanations. The EPR paper has become a very highly cited paper in QT. In the 1960s somebody showed that that explanation was not satisfactory, so that explanation is no longer considered valid. Einstein himself didn't like entanglement, calling it "Spooky action at a distance". But quantum theory calls for it and in the 1970s the first experimental proof was found.

Yes it is a bit of a problem. It does seem to require communication between the entangled particles that is faster than light speed. As far as I know there is no theoretical explanation of how it works, other than the fact that QT calls for it. It is just one of those things about QT that will drive you crazy if you really try to comprehend it.

I have a pretty good book about entanglement "The Dance of the Photons" by Anton Zeilinger The book was written in German, and was translated into English last year.

Bill Gill
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#37471 - 02/19/11 06:06 PM Re: General relativity on large scales. [Re: Bill]
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Bill, from the little I know of Zeilinger's book I suspect that it is very different from the general run of P S books. Would you recommend it to a non-scientist?
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#37477 - 02/20/11 01:13 AM Re: General relativity on large scales. [Re: Bill S.]
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Yes, I would. "The Dance of the Photons" is not highly technical, but I think it gives a pretty good overview of quantum entanglement for the average person who has just a little knowledge of QT. The thing I most like about it is that it concentrates mostly on quantum entanglement, rather than trying to cover the whole field of QT. I suppose somebody who has never heard anything about it might have a problem, but from your posts I think you would have no problem. Now that I have said that I will say that not everything he said made perfect sense to me. I will have to reread it when I get it back from my daughter. Of course the first time I read something I usually wind up not catching on to everything in it.

Bill
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#37482 - 02/20/11 04:29 PM Re: General relativity on large scales. [Re: Bill]
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Thanks, Bill. I have quite a large pile of books to work through, and somewhat limited time, but if/when I get round to this one I have no doubt there will be bits that don't make sense to me. As long as they are not the same bits that don't make sense to you, we may be able to help each other out. smile
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#39632 - 08/20/11 12:42 PM Re: General relativity on large scales. [Re: Bill S.]
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The war between Einstein and QT. Haha. It's so interesting to know how QT wronged and how Einstein wronged.

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#39651 - 08/21/11 08:15 PM Re: General relativity on large scales. [Re: gan]
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I am not sure too many buy the waveform collapse interpretation much anymore Bill S. You have to be a real die hard QM zealot to believe it to many problems with experiment observations.
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#39653 - 08/21/11 11:07 PM Re: General relativity on large scales. [Re: Orac]
Bill S. Offline
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Quote:
I am not sure too many buy the waveform collapse interpretation much anymore Bill S.


OK, but something seems to happen over a distance, so the situation remains much the same.
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#39663 - 08/22/11 10:18 AM Re: General relativity on large scales. [Re: Bill S.]
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Correct .. now remember our pesky attempt to kill QM information ... so we can start to add in some of the background.

The nasty part is GR is at odds with how you need to close it which is interesting as Hawking found out.

Results from LHC will be out Tuesday can't wait to see what it has to say ... I am still backing no stinking Higgs :-)
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#39705 - 08/24/11 12:22 AM Re: General relativity on large scales. [Re: Orac]
Bill S. Offline
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Originally Posted By: Orac
. now remember our pesky attempt to kill QM information ... so we can start to add in some of the background.


Explain, please.
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#39712 - 08/24/11 03:07 AM Re: General relativity on large scales. [Re: Bill S.]
Orac Offline
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The background is called the limits of uncertainy under QM.

A full discussion was published for New Scientist Magazine here is the copy (http://www.hermanusastronomy.co.za/wp-content/uploads/Uncertainty-untangled-June-2011-newsletter.doc)

Quote:

The uncertainty principle also applies to other pairs of quantities such as energy and time, and the spins and polarisations of particles in various directions. The energy-time uncertainty relation is the reason why quantum particles can pop out of nothingness and disappear again. As long as the energy, ΔE, they borrow to do that and the time, Δt, for which they hang around don't bust the uncertainty bound, the fuzzy logic of quantum mechanics remains satisfied.


It is for that reason we say with certainy that there are limits to what you can do with Quantum Information.

An attempt to delete quantum information it will change time as seen by the delayed-choice quantum eraser or it will change space position as seen by entanglement energy transportation.

Hence we say with certainty Quantum Information can not be created nor destroyed only changed from one form to another within our physical world.

Does this law sound familar .. a variant goes by the name of the 1st law of thermodynamics?

Perhaps you need us to demonstrate a Quantum Bomb to make you believe as Einstein had to for E=MC2 to be accepted :-)

Hey we have made a start its called a bose-nova (http://en.wikipedia.org/wiki/Bosenova).

I always loved Weiman's comment
Quote:

The 'missing' atoms are almost certainly still around in some form, but just not in a form that we can detect them in our current experiment,"


Hey we blew them to another time or another location but there around somewhere we just don't know where :-)

So yes Quantum Information can really blow you up!!!!!


Edited by Orac (08/24/11 04:08 AM)
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#39772 - 08/27/11 08:52 PM Re: General relativity on large scales. [Re: Orac]
Bill S. Offline
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To re-phrase the question in the OP: Does QT imply non-relative simultaneity?
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#39805 - 08/29/11 02:15 AM Re: General relativity on large scales. [Re: Bill S.]
Orac Offline
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I am not sure the question is actually valid for QM there is "no 3D space" in the quantum world thats why two entangled entities react simultaneously no matter how far apart you take them.

Relative in the way you are using them I take it means "relative space"????

The problem stems back to that problem of trying to resolve QM into classic physics the interpretation is always flawed at some point which is what we have spent 100 years studying and failing.

The bosenova explosion (http://en.wikipedia.org/wiki/Bosenova) really cemented how different a world QM is. Up until that moment many refused to think of QM information as real or important when it can rip matter apart and create energy from seemingly nowhere and classic physics can't explain it you really have a massive problem with classic physics.

Since then bosenova explosions have been studied and studied because classic physics has no way to explain it

http://www.nist.gov/public_affairs/releases/bosenova.cfm
http://physics.aps.org/articles/v1/13
http://physicsworld.com/cws/article/news/35556
http://www.physorg.com/news171188983.html


Edited by Orac (08/29/11 02:25 AM)
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#39815 - 08/29/11 08:29 AM Re: General relativity on large scales. [Re: Orac]
Orac Offline
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Funny while I was looking up what bosenova data was actually on the net I ran across this ... quite funny or not depends on your take.

http://blogs.nature.com/news/2008/09/scare_story_firefighting_a_wor.html
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#39825 - 08/29/11 07:51 PM Re: General relativity on large scales. [Re: Orac]
Bill S. Offline
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Originally Posted By: Orac
there is "no 3D space" in the quantum world


Can you say a bit more about this for the benefit of those of us who need to be spoon-fed?
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#39828 - 08/30/11 04:02 AM Re: General relativity on large scales. [Re: Bill S.]
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Quantum Mechanics is all about evolution of time when you break it down (http://en.wikipedia.org/wiki/Time_evolution)

It is the change of state brought about by the passage of time that is why it is described in terms of wave equations or probability.

So when I talk about a sine wave or tossing head/tails I don't need to describe a 3D space I am describing and arbitary space and an outcome waveform or probability even in these basic examples.

Classic mechanics deals with 3D world of physical stuff but what is time in this world it is an abstract thing. Why does time go one way .. as Brian Greene would say ... why do you see eggs fall and break but you never see broken eggs jump up of the floor and form a full egg. There is no way under classic physics to explain time and it's direction you basically have to accept it just is.

There is an equally important law in classic physics that is seldom discussed called Newtons 3rd law. It is seldom discussed becasue it is what many call a trivial or deduced law. Most do not realize there entire view of the world revolves around this trivial law that has no proof it is an observational law. It is also the most misunderstood law of physics .... http://en.wikipedia.org/wiki/Reaction_(physics)

The most important part of the 3rd law is actually that a body at rest will stay at rest. You don't see things get up and move without the application of a force and that force will be opposed.

So lets look at the classic physics pillars that have no explaination you just have to accept

- Energy can not be created nor destroyed only converted to other forms
- Time has direction and just is
- Newtons 3rd law
- Entropy


Quantum mechanics can provide answers to each of those

- Quantum information can not be created nor destroyed only converted from one form to another.
- Time describes the progression of the state transitions in a quantum system
- Quantum systems to be stable must have a ground state (http://en.wikipedia.org/wiki/Ground_state)
- Having a ground state imparts an entropic gradient


Do you see why we say the two great physics systems need to merge and why current QM physicists think it is unlikely QM will be rolled into classic physics.

So we move onto virtual partciles (http://en.wikipedia.org/wiki/Virtual_particle)

Quote:

The virtual particle forms of massless particles, such as photons, do have mass (which may be either positive or negative) and are said to be off mass shell. They are allowed to have mass (which consists of "borrowed energy") because they exist for only a temporary time, which in turn gives them a limited "range". This is in accordance with the uncertainty principle which allows existence of such particles of borrowed energy, so long as their energy, multiplied by the time they exist, is a fraction of Planck's constant


So we can now have virtual partciles which are borrowing energy because they exist for only a described time in an explict waveform and the space domain is of no consequence to them.


So if we have got you through all that you are now at the current QM point which says the universe is a quantum mechanical system the physical 3D space is a projectivism in which we experience this QM system.


So what does the QM universe really look like ... thats anybody's guess QM really has nothing to say about it at all. It could be like our real world with stuff hiding in the gaps like string theory says or we could be a complete hologram. QM systems demand no shape or space thats a demand of classic physics.


Thats my bad english attempt to give a layman's view Bill S. It's very touchie feely and light on detail but you can either read or ask if you need areas filled in with more background. I have avoided trying to give a particular QM story because obviously there are different views of what the QM universe looks like.

And if we got you through all that we can next discuss Quantum Discord (http://en.wikipedia.org/wiki/Quantum_discord). Sometimes QM doesn't need such a weird world after all :-)


Edited by Orac (08/30/11 04:52 AM)
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#39830 - 08/30/11 01:37 PM Re: General relativity on large scales. [Re: Orac]
Orac Offline
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Okay so above as Bill S wanted we discussed how and why many QM theorists thinks GR should be bought in under it.

The argument goes we have spent 100 years and countless small fortunes and brilliant minds and none could merge QM in GR. Infact the last great hope Mr Hawkings has officially given up
(http://www.newscientist.com/blogs/cultur...everything.html)

String theory and SUSY look in deep trouble with LHC findings classicality has a crisis.

So it's time to look seriously at the reverse.

The problem is the QM world is very messy as we discussed above because it really doesn't care for structure which as humans we tend to care very much about.

So enter the half way house we call Quantum Discord (http://en.wikipedia.org/wiki/Quantum_discord).

The argument goes QM needs no physical structure classic physics wants structure so let them both co-exist simultaneously on top of each other.

This is a very very new interpretation (birtdate 2001) and hence we represent the system as two sets of entropy because that is the big common between the two systems



This half way house is probably the last bastion of our hope for some degree of classical physics to survive if this falls we really are in the deep end with a full QM universe.

So are there any results that support the halfway house model.

Well there are tentative yes results

http://www.physorg.com/news/2011-08-quantum-entanglement.html
http://www.physorg.com/news/2011-08-entanglement-macroscopic-dissipation.html

For the more technical of you there is a presentation discussion that might interest you
http://qols.ph.ic.ac.uk/qi_ims/slides/slides_2010_08_10.pdf
http://www.physics.utoronto.ca/~alqasimi/talks/QES.pdf
http://arxiv.org/ftp/arxiv/papers/1106/1106.5097.pdf



Edited by Orac (08/30/11 01:49 PM)
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#39834 - 08/30/11 06:36 PM Re: General relativity on large scales. [Re: Orac]
Bill Offline
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Orac, I looked through your first reply to Bill S. I must say that I didn't pick up on everything you said, but one thing I think I got out of it is that QM is about the evolution of states with time, but you don't think classical physics is. Classical physics does incorporate evolution with time. After all calculating the orbit of a planet around the Sun certainly depends on time. And in GR Einstein developed a system that implicitly includes time as a part of the system (SpaceTime).

Now GR doesn't work when you come down to the atomic level, even at the level of many atoms. But QM doesn't work at all well when you come up to the level of solar systems. Trying to calculate the orbit of a planet from a QM perspective would be pretty much impossible.

So I figure that trying to get to GR from QM is going to be enormously difficult, if not impossible. But the problem is just as bad trying to go the other way. We need something different that will wind up incorporating both GR and QM.

Bill Gill
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#39835 - 08/31/11 12:44 AM Re: General relativity on large scales. [Re: Bill]
Orac Offline
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The interesting thing about GR Bill is remember we have a spacetime loaf. So GR involves time but it's a static backdrop there is no evolution involved infact time is a quite static thing in GR. Thats one of the problems of visualizing it in the GR backdrop.
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#39836 - 08/31/11 01:47 AM Re: General relativity on large scales. [Re: Orac]
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Originally Posted By: Orac
It is the change of state brought about by the passage of time


Could it not be equally true to say it is change brought about by physical processes, such as those designated by the laws of thermodynamics, and that time is simply an arbritrary measure of that change? This would seem particularly appropriate if we are dispensing with the concept of spacetime.

Quote:
So we can now have virtual partciles which are borrowing energy because they exist for only a described time in an explict waveform and the space domain is of no consequence to them.


How can virtual particles be said to exist hey are if not in space?
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