http://www.scientificamerican.com/article.cfm?id=splitting-time-from-space

I never really did like the notion of inseparable spacetime, tbqh.

--
Tim Cook
http://empyrean.freesitespace.net

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Tim Cook wrote:
> http://www.scientificamerican.com/article.cfm?id=splitting-time-from-space

Very cool.  I recently saw another approach, in which the collapse of the 
quantum probability wave forms is caused by gravity waves, which are too 
weak at the sub-atomic level to actually have an effect.  It'll be 
fascinating to see how all this plays out.

-- 
Darren New, San Diego CA, USA (PST)
   You know the kamikaze monsters in Serious Sam
     with the bombs for hands, that go AAAAAHHHHHHHH!
   I want that for a ring tone.

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Why do I always get the feeling that quantum gravity reverses the normal
scientific process of discovery-theory? In other words, normally a new
unknown phenomenon is discovered, studied, measured and then theories are
developed to explain how it works and perhaps why.

  With quantum gravity the direction seems reversed: They have formed the
theory of a gravitational quantum *first*, and now they are really hard
trying to discover it somehow.

-- 
                                                          - Warp

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Warp wrote:
>   With quantum gravity the direction seems reversed: They have formed the
> theory of a gravitational quantum *first*, and now they are really hard
> trying to discover it somehow.

The problem is that both relativity and QED (quantum electrodynamics - 
quantum mechanics for non-nuclear interactions) seem to be very accurate in 
their appropriate timescales. But QED assumes absolute time (AFAIK), and 
relativity assumes continuously differentiable space (and hence energy 
levels), so we know we can't resolve those two into one theory without 
changing one or the other. (At least, that's my understanding of the problem.)

The approach that QED uses has been successfully applied to nuclear 
interactions with the strong and weak nuclear forces, as well as 
interactions between quarks (quantum chromodynamics). In other words, it 
looks like every force *except* gravity behaves like 
two-dimensional-probability "waves" traveling at the speed of light on average.

Hence the assumption that gravity is likely to also play by that rule, with 
gravitons mediating the effects of gravity on the small scale with 
statistical properties making it look smooth and consistent and "not 
quantum" over larger scales.

tl;dr - relativity and quantum are mathematically incompatible, and quantum 
accurately describes everything *except* gravity, so the assumption is 
gravity is wrong.

-- 
Darren New, San Diego CA, USA (PST)
   You know the kamikaze monsters in Serious Sam
     with the bombs for hands, that go AAAAAHHHHHHHH!
   I want that for a ring tone.

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Warp wrote:
>   Why do I always get the feeling that quantum gravity reverses the normal
> scientific process of discovery-theory? In other words, normally a new
> unknown phenomenon is discovered, studied, measured and then theories are
> developed to explain how it works and perhaps why.
> 
>   With quantum gravity the direction seems reversed: They have formed the
> theory of a gravitational quantum *first*, and now they are really hard
> trying to discover it somehow.

Had a look at String Theory lately? ;-)

http://www.xkcd.com/171/

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:4b0cf846@news.povray.org...

> In other words, normally a new
> unknown phenomenon is discovered, studied, measured and then theories are
> developed to explain how it works and perhaps why.

This is a very neat and tidy, but ultimately wrong synopsis of how science,
or at least physics, has been working for over the last century, during
which time theories have often ventured far beyond what needs to be
explained. Of course they have simultaneously been falling far short of
explaining what needs to be explained, so it's a really complex picture.

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somebody <x### [at] ycom> wrote:
> "Warp" <war### [at] tagpovrayorg> wrote in message
> news:4b0cf846@news.povray.org...

> > In other words, normally a new
> > unknown phenomenon is discovered, studied, measured and then theories are
> > developed to explain how it works and perhaps why.

> This is a very neat and tidy, but ultimately wrong synopsis of how science,
> or at least physics, has been working for over the last century, during
> which time theories have often ventured far beyond what needs to be
> explained. Of course they have simultaneously been falling far short of
> explaining what needs to be explained, so it's a really complex picture.

  Well, *usually* science goes through the cycle:

1) We observe some phenomenon,
2) We study and measure the phenomenon.
3) We formulate hypotheses, and if these hypotheses can make enough accurate
   predictions which match new observations, they are made into theories.
4) If new observations and measurements contradict the existing theories,
   they are revised, or entirely new hypotheses are formulated, so we go
   back to step 1.

  In this particular case, however, I have the feeling that an observed
phenomenon (gravity) is tried to forcefully be fit into an existing theory
(quantum mechanics) even though it's contradicting it. In other words,
the theory is that "everything must be quantized", and they are observing
that "gravity doesn't seem to be quantized", and rather than revising the
theory they are trying to forcefully make gravity quantized to fit the
theory.

  Somehow I get the feeling that it's a bit the same as saying "the Newtonian
gravity laws are the truth" and then trying really hard to make the mechanics
of Mercury fit into the Newtonian laws of gravity, rather than accepting that
it doesn't fit, and devising a new theory which does fit observed phenomena.

-- 
                                                          - Warp

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>  Well, *usually* science goes through the cycle:
>
> 1) We observe some phenomenon,
> 2) We study and measure the phenomenon.
> 3) We formulate hypotheses, and if these hypotheses can make enough 
> accurate
>   predictions which match new observations, they are made into theories.
> 4) If new observations and measurements contradict the existing theories,
>   they are revised, or entirely new hypotheses are formulated, so we go
>   back to step 1.

Didn't Einstein predict black holes before we found any?

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scott wrote:
>>  Well, *usually* science goes through the cycle:
>>
>> 1) We observe some phenomenon,
>> 2) We study and measure the phenomenon.
>> 3) We formulate hypotheses, and if these hypotheses can make enough 
>> accurate
>>   predictions which match new observations, they are made into theories.
>> 4) If new observations and measurements contradict the existing theories,
>>   they are revised, or entirely new hypotheses are formulated, so we go
>>   back to step 1.
> 
> Didn't Einstein predict black holes before we found any?

It's not uncommon for a new theory to explain observed phenomina but 
also predict something that nobody has seen before. The interesting 
question is whether the thing is seen later.

(Isn't there some theory that predicts that Weakly Interacting Massive 
Particles exist, yet nobody has ever seen one?)

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:4b0e5f8a@news.povray.org...

>   In this particular case, however, I have the feeling that an observed
> phenomenon (gravity) is tried to forcefully be fit into an existing theory
> (quantum mechanics) even though it's contradicting it. In other words,
> the theory is that "everything must be quantized", and they are observing
> that "gravity doesn't seem to be quantized", and rather than revising the
> theory they are trying to forcefully make gravity quantized to fit the
> theory.

In an ideal world, QM should be dead wrong. Unfortunately, it's been
verified beyond any reasonable (and unreasonable) doubt. So what are
physicists to do? If one could revise QM+QED+QCD+SM to fit GR in gracefully,
it would have been done.

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