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/

Post a reply to this message

"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.

Post a reply to this message

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

Post a reply to this message

>  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?

Post a reply to this message

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?)

Post a reply to this message

"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.

Post a reply to this message

scott <sco### [at] scottcom> 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?

  That would be step #3 above.

  What Einstein did not do is to observe a black hole, notice that it did
not conform to his theory, but tried to make it conform anyways.

  That's what I feel QM is doing.

-- 
                                                          - Warp

Post a reply to this message

Invisible <voi### [at] devnull> wrote:
> It's not uncommon for a new theory to explain observed phenomina but 
> also predict something that nobody has seen before.

  Actually that's one of the requisites in order to change a hypothesis into
a theory. (Ok, not a requisite per se, but if it the hypothesis does predict
something and later it results that the prediction was correct, that's a
strong incentive into making the hypothesis a theory.)

-- 
                                                          - Warp

Post a reply to this message

somebody <x### [at] ycom> wrote:
> In an ideal world, QM should be dead wrong. Unfortunately, it's been
> verified beyond any reasonable (and unreasonable) doubt.

  *Part* of it has been verified. As we have seen, it's currently unsuitable
to explain everything.

-- 
                                                          - Warp

Post a reply to this message

>  What Einstein did not do is to observe a black hole, notice that it did
> not conform to his theory, but tried to make it conform anyways.
>
>  That's what I feel QM is doing.

Maybe I missed something, but has anything been observed with regard to 
gravity that doesn't conform to QM?  I thought the issue is with gravity 
that they just haven't been able to come up with a way to prove or disprove 
the predictions that QM makes.

Post a reply to this message