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

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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

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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

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>  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.

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scott wrote:
> 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.

I thought that QM simply doesn't describe gravity *at all*, and that was 
the problem.

Then again, I know nothing about QM, so.....

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Warp wrote:
>   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.

The basic "faith" of science is that physical laws are consistent 
everywhere, everywhen, etc.  (Except perhaps for singularities like black 
holes or the big bang or whatever.)  The assumption, in other words, that 
the *true* theory of gravity is consistent with the *true* theory of QM is 
taken on faith.

Since QM is much, much easier to measure, we have much, much better evidence 
that it's correct at the energies well below LHC levels. Since QM seems very 
correct, the assumption is that at levels where we can't currently measure 
gravity, it's likely to act like QM does.

> 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.

They *are* revising the theory. It's the theory of gravity they're revising.

I think there are also constant revisions of QM being proposed that 
harmonize it with gravity. I've seen people suggest that gravity is caused 
by the nearness of QM "multi-worlds", or that string theory predictions that 
relate the two, etc.

> and devising a new theory which does fit observed phenomena.

In what way is quantum gravity not devising a new theory? The problem you're 
seeing, I think, is that it's easier to measure QM effects than gravity 
effects, since gravity is many orders of magnitude weaker than the weakest 
QM interaction.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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Invisible wrote:
> I thought that QM simply doesn't describe gravity *at all*, and that was 
> the problem.

There are a number of different theories of "QM", depending on what you're 
looking at.

QM of photons interacting with electrons is QED, Quantum Electrodynamics. 
That covers everything but nuclear reactions and gravity. I.e., all of 
chemistry and everything that's based on chemistry, as well as why electrons 
"orbit" the nucleus, *why* the periodic table of elements is how it is, 
electricity, friction, lasers, pauli exclusion, partial and total 
reflections, diffraction gratings, polarization, etc.

There's a kind of QM (whose name I don't know) that accounts for the strong 
and weak nuclear forces. It has muons an mesons and stuff like that acting 
like photons, with neutrons and protons acting like electrons, and etc. (I'm 
probably messing all that up, but...) It's essentially the same formula with 
different numbers plugged in. This theory is not so well confirmed, because 
the numbers are a couple orders of magnitude bigger - i.e., the same 
difference between a chemical bomb and a nuclear bomb.

QCD is quantum chromodynamics, which I think accounts for all the different 
subatomic particles based on quarks. Again, it's essentially the same 
process, with a few extra kinds of numbers thrown in (but which behave the 
same way). Kind of like having polarization in other directions.

So given that every other "action at a distance" seems to follow the same 
basic formulas and seems to move at the speed of light, and that gravity 
itself seems to move at the speed of light, it's not surprising that gravity 
is thought to maybe follow the same basic formulas.

Just like people thought photons were waves because they followed the same 
basic formulas as waves do, but it turns out they're 100% always particles, 
it's sort of like gravity perhaps follows the same math as curved space 
time, but maybe is exchange particles after all.  I have never heard of us 
actually measuring actual curved space-time unambiguously. I'd be interested 
in hearing if we did.

Or, it's possible that gravity works in a way that's just incompatible with 
QM and the two physically cannot be unified regardless of theory chosen. :)

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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Warp wrote:
> 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.

What's missing in QM? Or, rather, what has QM predicted that it's unsuitable 
to explain?

That QM doesn't explain relativity doesn't mean QM is wrong. It just means 
it doesn't explain QM, any more than relativity explains nuclear reactions.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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Darren New wrote:

> QM of photons interacting with electrons is QED, Quantum 
> Electrodynamics. That covers everything but nuclear reactions and 
> gravity. I.e., all of chemistry and everything that's based on 
> chemistry, as well as why electrons "orbit" the nucleus, *why* the 
> periodic table of elements is how it is, electricity, friction, lasers, 
> pauli exclusion, partial and total reflections, diffraction gratings, 
> polarization, etc.

Wait, back up a sec - you mean there's a *reason* why the transition 
metals exist? And people actually know WTF this reason is??

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
> Wait, back up a sec - you mean there's a *reason* why the transition 
> metals exist? And people actually know WTF this reason is??

Yes.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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