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Thu Jan 10, 2013, 01:37 PM

Einstein Was Right: Space-Time Is Smooth, Not Foamy

Space-time is smooth rather than foamy, a new study suggests, scoring a possible victory for Einstein over some quantum theorists who came after him.

In his general theory of relativity, Einstein described space-time as fundamentally smooth, warping only under the strain of energy and matter. Some quantum-theory interpretations disagree, however, viewing space-time as being composed of a froth of minute particles that constantly pop into and out of existence.

It appears Albert Einstein may have been right yet again.

A team of researchers came to this conclusion after tracing the long journey three photons took through intergalactic space. The photons were blasted out by an intense explosion known as a gamma-ray burst about 7 billion light-years from Earth. They finally barreled into the detectors of NASA's Fermi Gamma-ray Space Telescope in May 2009, arriving just a millisecond apart.

more
http://www.space.com/19202-einstein-space-time-smooth.html

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Reply Einstein Was Right: Space-Time Is Smooth, Not Foamy (Original post)
n2doc Jan 2013 OP
Mnemosyne Jan 2013 #1
Peace Patriot Jan 2013 #2
Speck Tater Jan 2013 #3
tama Jan 2013 #5
tama Jan 2013 #4
bananas Jan 2013 #7
bananas Jan 2013 #6

Response to n2doc (Original post)

Thu Jan 10, 2013, 01:57 PM

1. Maybe a dumb question, but how are these photons affected based on the GP-B test results?

Hope I am clear enough, just trying to learn.

Thanks!

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Response to n2doc (Original post)

Thu Jan 10, 2013, 02:48 PM

2. I don't pretend to understand this science, but the article itself says the result is very iffy.

So the headline is inaccurate ("Einstein was right") and does NOT reflect the content of the article. Read down a few paragraphs and the article says...

---------

"...the new study is a strike against the foam's existence as currently imagined, though not a death blow."
http://www.space.com/19202-einstein-space-time-smooth.html

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It goes on to explain the iffiness of the study's results. So the truth is that this result does NOT prove Einstein right and other physicists wrong. It may even point to "other physics"--that neither "side" is right or wrong; both just don't know enough. I can understand the study's authors wanting to get known for proving Einstein "right" but news editors and headline writers should not buy into ambition--but rather try to stick to the facts.

The headline should read: "Einstein MAY HAVE BEEN Right: Space-Time Is Smooth, Not Foamy.

Inaccuracy like this affects people and affects science. There may be some young budding physicist somewhere who reads that headline and is discouraged about proving Einstein wrong. I hope he or she is literate enough to read further, and learn that the study does not support the headline--that the question is still open and that "new physics" may be required to understand the true nature of space-time. But sometimes genius in math and physics does not go hand in hand with literary savvy. Maybe that kid will give up--abandon, forget, not pursue--some germ of an idea that might have overturned Einstein later on, or opened up a entirely new chapter in our understanding of the Universe.

Truth in reporting is THAT important. Or maybe there are some existing physicists in need of grants to further pursue the "foam" (as opposed to "smooth") theory--and some idiot politician has read that headline and laughs in their faces. ('Prove Einstein WRONG?" he will spout, 'Next you'll be trying to prove that God does not exist!') (We do have such idiot politicians in control of lots and lots of money!)

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Aside from all this, I am quite awed by scientific investigation that can trace three photons over 7 billion light years. Whether or not their conclusions (or perhaps it's more accurate to say 'educated guesses'), as to the meaning of the condition of these three photons upon arrival at Planet Earth, are correct, is another matter--which the article itself says needs more experiment and study (and perhaps "new physics"). But the pursuit of this and other knowledge, and all that it has taken to mount the pursuit--in lives, courage and treasure, over the centuries--is truly inspiring, and this particular investigation literally made my jaw drop in admiration. Three photons. 7 billion light years. Jiminy Crickets!** That's a lo-o-o-o-ong frigging amount of space-time!

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**("When You Wish Upon A Star.")

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Response to n2doc (Original post)

Thu Jan 10, 2013, 03:21 PM

3. What about the Casimir Effect?

 

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

It's my understanding that the Casimir effect pretty conclusively proves the existence of virtual particles in the Quantum Foam.

And doesn't the tunnel diode, the keystone of model computer chips, depend on quantum tunneling which only happens if virtual pairs pop into and out of existence in the quantum foam?

And what about Hawking Radiation from black holes. Isn't that also a quantum foam, or tunneling effect? A pair of virtual particles pops into existence, one inside the event horizon and one outside. The outside one escapes becoming a real particle, thus causing mass to evaporate from the black hole.

As usual, fluff pieces written for general consumption oversimplify to the point of becoming silly.

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Response to Speck Tater (Reply #3)

Thu Jan 10, 2013, 04:17 PM

5. Indeed

 

Mentioned Casimir Effect in my post below, but as for Hawking Radiation, it's not empirical science but axiomatic deduction (as are black hole singularities in general, theory dependent predictions and thought experiments of GR which are not empirically confirmed and it is questionable if they can be confirmed).

Here's a good explanation of the problem of uniting QM and GR:
http://www.infoplease.com/cig/theories-universe/quantum-mechanics-vs-general-relativity.html

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Response to n2doc (Original post)

Thu Jan 10, 2013, 03:55 PM

4. Wheeler's idea

 

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

Space-time "bubbling" with vacuum fluctuations of virtual particle pairs is considered the explanation of e.g. Casimir Effect (http://en.wikipedia.org/wiki/Casimir_effect).

On cosmic scales the issue is dependent from finding theory of quantum gravity, which is still very much work in progress. Wiki on Quantum foam mentions empirical evidence of gamma ray delays in support of this approach: http://www.news.ucdavis.edu/search/news_detail.lasso?id=8364

How Wheeler's delayed choice experiment (http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment) on cosmic scale relates to this question and empirical results is a... good question.

Too bad the OP article is so sloppy and has no link to the actual article.

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Response to tama (Reply #4)

Thu Jan 10, 2013, 05:30 PM

7. I think I found the abstract

http://adsabs.harvard.edu/abs/2013AAS...22115209N

Title: Limits on Cosmological Dispersion from Photon Bunches in GRB 090510 from Fermi LAT Data
Authors: Nemiroff, Robert J.; Connolly, R.; Kostinski, A.
Affiliation: AA(Michigan Technological Univ.), AB(Michigan Technological Univ.), AC(Michigan Technological Univ.)
Publication: American Astronomical Society, AAS Meeting #221, #152.09
Publication Date: 01/2013
Origin: AAS
Abstract Copyright: (c) 2013: American Astronomical Society
Bibliographic Code: 2013AAS...22115209N

Abstract

Three photons spanning about 30 GeV arrived within about one millisecond from the Fermi-detected GRB 090510A at a redshift of about 0.9. Although conceivably a > 3 sigma statistical fluctuation, when taken at face value, this photon bunch -- quite possibly a classic GRB pulse -- leads to a relatively tight bound on the ability of our universe to disperse high energy photons. Specifically given a generic dispersion relation where the time delay is proportional to the photon energy to the first power the limit on the dispersion strength is k1 < 1.61 x 10-5 sec Gpc-1 GeV-1. Two other short duration photon bunches bolster the statistical significance of this limit. In the context of some theories of quantum gravity this conservative bound translates into an minimum energy scale greater than 525 m_Planck suggesting that spacetime is smooth at energies perhaps a factor of 1000 below the Planck length.

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Response to n2doc (Original post)

Thu Jan 10, 2013, 05:22 PM

6. Spacetime more like Einsteinian whiskey than foamy beer

I like this title better!
http://www.indianexpress.com/news/spacetime-more-like-einsteinian-whiskey-than-foamy-beer/1057455/0

Spacetime more like Einsteinian whiskey than foamy beer

ANI : Washington, Thu Jan 10 2013, 15:39 hrs

Spacetime may be less like foamy quantum beer and more like smooth Einsteinian whiskey, according to a physicist.

Robert Nemiroff of Michigan Technological University and his team reached this heady conclusion after studying the tracings of three photons of differing wavelengths recorded by NASA’s Fermi Gamma-ray Space Telescope in May 2009.

The photons originated about 7 billion light-years away from Earth from a gamma-ray burst and arrived at the orbiting telescope a mere millisecond apart.

“Gamma-ray bursts can tell us some very interesting things about the universe,” Nemiroff said.

<snip>



ANI is Asian News International: http://en.wikipedia.org/wiki/Asian_News_International

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