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Theoretical physics: The origins of space and time
Nature ^ | 8/28/13 | Zeeya Merali

Posted on 08/28/2013 3:33:35 PM PDT by LibWhacker

Many researchers believe that physics will not be complete until it can explain not just the behaviour of space and time, but where these entities come from.

“Imagine waking up one day and realizing that you actually live inside a computer game,” says Mark Van Raamsdonk, describing what sounds like a pitch for a science-fiction film. But for Van Raamsdonk, a physicist at the University of British Columbia in Vancouver, Canada, this scenario is a way to think about reality. If it is true, he says, “everything around us — the whole three-dimensional physical world — is an illusion born from information encoded elsewhere, on a two-dimensional chip”. That would make our Universe, with its three spatial dimensions, a kind of hologram, projected from a substrate that exists only in lower dimensions.

This 'holographic principle' is strange even by the usual standards of theoretical physics. But Van Raamsdonk is one of a small band of researchers who think that the usual ideas are not yet strange enough. If nothing else, they say, neither of the two great pillars of modern physics — general relativity, which describes gravity as a curvature of space and time, and quantum mechanics, which governs the atomic realm — gives any account for the existence of space and time. Neither does string theory, which describes elementary threads of energy.

Van Raamsdonk and his colleagues are convinced that physics will not be complete until it can explain how space and time emerge from something more fundamental — a project that will require concepts at least as audacious as holography. They argue that such a radical reconceptualization of reality is the only way to explain what happens when the infinitely dense 'singularity' at the core of a black hole distorts the fabric of space-time beyond all recognition, ...

(Excerpt) Read more at nature.com ...


TOPICS: Science
KEYWORDS: bang; big; origin; physics; space; stringtheory; theoretical; time
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To: PoloSec

I loved that article.

Makes perfect sense and only reinforced what I’d always known but had never seen explained.


21 posted on 08/28/2013 4:58:41 PM PDT by jodyel
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To: LibWhacker
Some interesting pull-quotes & observations from the various sections in the article:
[i]f theories cannot be tested, “then to me, they are not science. They are just religious beliefs, and they hold no interest for me.”
The reversed cosmos contracted towards the Big Bang, as expected. But as it approached the fundamental size limit dictated by loop quantum gravity, a repulsive force kicked in and kept the singularity open, turning it into a tunnel to a cosmos that preceded our own... [a]n observer travelling deep into the heart of a black hole would encounter not a singularity, but a thin space-time tunnel leading to another part of space.
“It is early days and our job is hard because we are fishes swimming in the fluid at the same time as trying to understand it,”
[a]dding causality changed everything. After all, says Loll, the dimension of time is not quite like the three dimensions of space. “We cannot travel back and forth in time,” she says. So the team changed its simulations to ensure that effects could not come before their cause — and found that the space-time chunks started consistently assembling themselves into smooth four-dimensional universes with properties similar to our own... [s]ome suggest that the appearance of dark energy is a sign that our Universe is now growing a fourth spatial dimension.
[t]he three-dimensional universe is being held together by quantum entanglement on the boundary — which means that in some sense, quantum entanglement and space-time are the same thing.
22 posted on 08/28/2013 5:15:43 PM PDT by mikrofon (Humpday BUMP-ty)
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To: kabumpo

Any favorites? I like Solaris and A Perfect Vacuum.


23 posted on 08/28/2013 5:15:56 PM PDT by dr_lew
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To: no-to-illegals

Some people think “time” doesn’t even exist—that it’s just a concept to help us deal with mortality and sequences of events in the eternal now.


24 posted on 08/28/2013 5:15:58 PM PDT by Trod Upon (Every penny given to film and TV media companies goes right into enemy coffers. Starve them out!)
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To: John Valentine
The biggest difference between a duffer and a PhD theoretical Physicist when it comes to cosmology is that the Physicist knows how to make his ideas sound sophisticated - he knows the language of his trade.

Rather simplistic and naïve.

The difference between a duffer and a PhD theoretical Physicist is mathematics.

A theoretical Physicist cosmologist can test his theory with mathematical models. A sound cosmological theory will have a mathematical model that will confirm or disprove its possibility. If the mathematics determine that the theory is possible then a physical experiment can be designed to test the theory’s relationship to the real world.

A duffer would be hard pressed to design a mathematical model to demonstrate that the universe resides on the back of a turtle or any other theory he may dream up and be harder pressed to design an experiment to provide physical proof to backup that theory.

25 posted on 08/28/2013 5:21:04 PM PDT by Pontiac (The welfare state must fail because it is contrary to human nature and diminishes the human spirit.)
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To: mikrofon
[t]he three-dimensional universe is being held together by quantum entanglement on the boundary — which means that in some sense, quantum entanglement and space-time are the same thing.

Heh. This is physics today, "held together by quantum entanglement at the boundary." All dressed up and nowhere to go.

26 posted on 08/28/2013 5:23:47 PM PDT by dr_lew
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To: Pontiac

Simplistic and naive, maybe. I agree.

But I did say that the physicist knows the language of his trade. Maybe you didn’t understand what I was getting at, but that language IS mathematics.

I will disagree with you on one point: mathematical models will NOT always prove or disprove a theory. They will ten k to confirm or disconfirm, but the mathematics is always also subject to inspection and investigation. The history of physics is replete with theories once confirmed by mathematical models which were later shown - both the theory and the model - to be incomplete or inadequate.

My point was and is that cosmology is supremely speculative.


27 posted on 08/28/2013 5:29:18 PM PDT by John Valentine (Deep in the Heart of Texas)
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To: LibWhacker

Pass the Dutchie ‘pon the left hand side, man.


28 posted on 08/28/2013 5:38:13 PM PDT by Lawgvr1955 (You can never have too much cowbell !!)
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To: jodyel

Thanks for the link.

I’m told that gravity bends space. I know relativity bends my mind. Schroeder’s work continues the process.

I think it is standard relativity theory that time dilation depends on the (location and velocity of the) observer. The passage of time as seen from earth today would likely differ from the passage of time as seen by an observer at the time and location of the big bang. Could 15 billion years be consistent with 6 thousand years? Maybe so.


29 posted on 08/28/2013 6:21:30 PM PDT by ChessExpert (The unemployment rate was 4.5% when Democrats took control of Congress in 2006.)
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To: dr_lew

Quantum Entanglement & Space-Time

30 posted on 08/28/2013 6:22:34 PM PDT by mikrofon (Cosmic Threads)
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To: John Valentine

As a physics major I always looked at my major as trying to figure out the language of God....but I know what you mean there were always a few of “those types”.


31 posted on 08/28/2013 6:47:18 PM PDT by reed13k (For evil to triumph it is only necessary for good men to do nothing.)
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To: ChessExpert

Another freeper posted the article and we both came to the conclusion that determining the age depends on whose perspective one is looking from.....anyone outside time and space (God) or those inside time and space (us, angels, demons).

My post like the above is 92 and OP agreed on 94.

http://www.freerepublic.com/focus/f-religion/3051495/posts

Interesting stuff.


32 posted on 08/28/2013 6:50:10 PM PDT by jodyel
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To: null and void
I have a way of explaining inflation without breaking the speed limit. I’d like to fly it by someone skilled in the art in private so I don’t embarrass my self in public with an obvious mistake...

Dude, knock yourself out. "Inflation" is a bunch of hand-waving for observations of the existing universe that they just can't explain. Your theory is as good as any.

33 posted on 08/28/2013 7:24:33 PM PDT by zeugma (Is it evil of me to teach my bird to say "here kitty, kitty"?)
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To: zeugma

Can’t? Never say never...


34 posted on 08/28/2013 7:27:16 PM PDT by null and void (Frequent terrorist attacks OR endless government snooping and oppression? We can have both!)
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To: Pontiac
A theoretical Physicist cosmologist can test his theory with mathematical models. A sound cosmological theory will have a mathematical model that will confirm or disprove its possibility. If the mathematics determine that the theory is possible then a physical experiment can be designed to test the theory’s relationship to the real world.

One of the fundamental problems with modern physics IMO is that they are chasing down the 'string theory' rabbit hole. String theory isn't even wrong, and pretty much can't really be tested.

35 posted on 08/28/2013 7:31:09 PM PDT by zeugma (Is it evil of me to teach my bird to say "here kitty, kitty"?)
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To: Pontiac

the trouble is that something like string theory appears to mathematically beautiful to many physicists but it is neither prescriptive or descriptive of reality. That is, the math doesn’t describe any part of visible reality nor can the math be used to solve real life problems.


36 posted on 08/28/2013 7:55:49 PM PDT by ckilmer
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To: 6SJ7; AdmSmith; AFPhys; Arkinsaw; allmost; aristotleman; autumnraine; backwoods-engineer; ...

Thanks LibWhacker, and thanks to anyone whose pings I missed.

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37 posted on 08/28/2013 8:34:45 PM PDT by SunkenCiv (It's no coincidence that some "conservatives" echo the hard left.)
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To: LibWhacker

So what is on the other side of the Universe?....


38 posted on 08/28/2013 9:14:20 PM PDT by Intolerant in NJ
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To: LibWhacker

The holographic image of me ruling the entire universe isn’t far off now.


39 posted on 08/28/2013 9:50:32 PM PDT by Bullish (Psalm 46)
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To: no-to-illegals
I consider time to not be relevant, therefore my conclusion is the universe is one dimensional.

Get to the point!

40 posted on 08/28/2013 9:59:38 PM PDT by Sirius Lee (All that is required for evil to advance is for government to do "something")
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