http://sifter.org/~aglisi/JournalG/20071114.html

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Tom Galvin wrote:
> http://sifter.org/~aglisi/JournalG/20071114.html

My main experience with this has been the feeling of "boy, I wish I knew 
enough physics to judge this paper's merits for myself".  It is sort of 
interesting to watch though, I have to admit.

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Le 17.11.2007 02:55, Kevin Wampler nous fit lire :
> Tom Galvin wrote:
>> http://sifter.org/~aglisi/JournalG/20071114.html
> 
> My main experience with this has been the feeling of "boy, I wish I knew
> enough physics to judge this paper's merits for myself".  It is sort of
> interesting to watch though, I have to admit.

Interestingly enough, 8 dimensions spaces does have a
cross-product... sort of.

-- 
The superior man understands what is right;
the inferior man understands what will sell.
-- Confucius

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One thing I have never really understood is why they are so vehemently
trying to find a "unified theory of everything".

  We have models which describe how things work at quantum scale, and we
have models which describe how things work at macroscale (including high
speeds and high masses). Neither model describes well the other, but why
is this such a big deal? Why can't we have two (or more) models at the
same time?

  This may be a far-fetched analogy, but we have theories and models of
how car engines should be built, and we have theories and models of how
skyscrapers should be built. Neither model can be used to describe the
other situation, but so what? That doesn't cause any problems. If you
are building a car engine, use the car engine model. If you are building
a skyscraper, use the skyscraper model. Where's the problem? Why would
we even need a "unified model" which describes both car engines and
skyscrapers at the same time? There's no need, and it would only completely
unnecessarily complicate things.

  Is it just a question of coolness, or is there some practical issue
in play here?

-- 
                                                          - Warp

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Following links from there, I found this an interesting read:

http://cosmicvariance.com/2007/11/01/dark-matter-still-existing/

-- 
                                                          - Warp

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Warp nous apporta ses lumieres en ce 2007/11/17 06:31:
>   Following links from there, I found this an interesting read:
> 
> http://cosmicvariance.com/2007/11/01/dark-matter-still-existing/
> 
The defenition of "dark matter":
Any matter that we can't directly observe.
What can it be? Diffuse gases, dust clouds, "sand" clouds, "gravel" cloud, 
cluster of rogue planets, failed and dead stars, brown stars, IR stars. The list 
goes from the easiest to detect to the hardest.

-- 
Alain
-------------------------------------------------
When the bosses talk about improving productivity, they are never talking about 
themselves.

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Warp wrote:
>   One thing I have never really understood is why they are so vehemently
> trying to find a "unified theory of everything".

	Probably different people have different answers/reasons.

	Theoretical physicists are rarely concerned with what is practical. An 
underlying assumption among many is that there *is* a universal theory, 
and since there is, the models they currently have don't describe the 
"truth" (although they may describe all of it).

	Also, if they find such a theory, they may be able to predict phenomena 
not seen otherwise. His paper predicts a number of new particles, for 
example. Perhaps no one would have observed them (assuming its true) in 
experiments had they not been guided on where to look by such a theory.

	And, I assume, there are still phenomena that current physics doesn't 
explain adequately. So they assume a universal theory will do a better job.

	I remember as an undergrad arguing with my engineering professors on a 
very similar concept. In circuits, we learn certain equations (Ohm's 
Law, oscillating systems, etc). However, most professors don't point out 
the analogy between those systems and mechanical ones (the equations are 
of the exact same mathematical form).  Later when the students studied 
mechanics courses, almost no one saw the relationship and they 
re-learned all those properties. And I'm sure they'd do it again for any 
other oscillating system they'd study.

	When I took basic physics courses, they did things differently. They 
first studied the mathematical properties of that class of equations 
(perhaps motivated by a real world example). Once all the math was taken 
care of, they went through one physical system after another, showed 
that their governing equations had the same form, and then obtained the 
basic physical properties of all those systems in one fell swoop.

	Now they sure could have gone the route that the engineers did. But I 
think everyone would agree they "understood" the systems better once 
they understood the unifying principles (the properties of the 
mathematical equations in abstract).

-- 
Why do the Alphabet song and Twinkle, Twinkle Little Star have the same 
tune?


                     /\  /\               /\  /
                    /  \/  \ u e e n     /  \/  a w a z
                        >>>>>>mue### [at] nawazorg<<<<<<
                                    anl

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Warp wrote:
>   One thing I have never really understood is why they are so vehemently
> trying to find a "unified theory of everything".
> 
>   We have models which describe how things work at quantum scale, and we
> have models which describe how things work at macroscale (including high
> speeds and high masses). Neither model describes well the other, but why
> is this such a big deal? Why can't we have two (or more) models at the
> same time?
Because there is a medium scale and mixed scales?
For example one of the things we cannot describe at the moment (IIRC) is 
the behaviour of one electron in a big gravitational field e.g. close to 
a black hole. You need both quantum mechanics and relativity for that.
One of the jokes of one of my quantum teachers was that you can see the
progress of science in what systems of particles you can solve. In 
newtonian physics the three body system is unsolvable. Then with general 
relativity the 2 body problem becomes analytically unsolvable. With the 
addition of quantum mechanics the behaviour of a single particle is 
beyond reach (see above) and nowadays we cannot even solve the vacuum 
anymore.

> 
>   This may be a far-fetched analogy, but we have theories and models of
> how car engines should be built, and we have theories and models of how
> skyscrapers should be built. Neither model can be used to describe the
> other situation, but so what? That doesn't cause any problems. If you
> are building a car engine, use the car engine model. If you are building
> a skyscraper, use the skyscraper model. Where's the problem? Why would
> we even need a "unified model" which describes both car engines and
> skyscrapers at the same time? There's no need, and it would only completely
> unnecessarily complicate things.
Unless you want to build a movable skyscraper. Trust me, someone will 
one day.

> 
>   Is it just a question of coolness, or is there some practical issue
> in play here?
> 
Whether there is a practical advantage will only show after unification. 
But of course the main problem is that it is bloody annoying at parties.

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Warp wrote:
>   One thing I have never really understood is why they are so vehemently
> trying to find a "unified theory of everything".

As Mueen stated, it's probably to predict what currently can't be 
predicted. He was talking about the properties of particles which still 
have yet to be discovered, but the implications could reach farther. In 
fact, if we could determine *all* the factors present during the Big 
Bang, we will be one step closer to predicting future events. Of course, 
to accurately model the Universe we must use other parallel universes 
for computational purposes. I don't think we will ever reach such an 
advanced state (assuming such a thing is possible). We will most likely 
wipe ourselves out long before making such progress.

>   This may be a far-fetched analogy, but we have theories and models of
> how car engines should be built, and we have theories and models of how
> skyscrapers should be built. Neither model can be used to describe the
> other situation, but so what? That doesn't cause any problems. If you
> are building a car engine, use the car engine model. If you are building
> a skyscraper, use the skyscraper model. Where's the problem? Why would
> we even need a "unified model" which describes both car engines and
> skyscrapers at the same time? There's no need, and it would only completely
> unnecessarily complicate things.

In light of our current state of knowledge regarding basic physics, your 
assumption makes sense. But what if we do find a unified theory of all 
existence which makes us reconsider our severely limited knowledge of 
low-level physics? We might find that the approach to engineering a 
skyscraper and our approach to engineering a car engine becomes, er, 
more unified :)

>   Is it just a question of coolness, or is there some practical issue
> in play here?
> 
There are always practical issues regarding the advancement of knowledge.

Sam

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Warp wrote:
>   Is it just a question of coolness, or is there some practical issue
> in play here?

I think it's more a combination of two things:

One - that the two theories are incompatible. Relativity requires 
continuous functions. Quantum disallows continuous functions. If space 
(including gravity etc) is smoothly continuous at the smallest levels, 
quantum theory would give the wrong answer. If space were discontinuous 
at the smallest levels, relativity would give the wrong answers, even at 
the big sizes. So, basically, people *know* that one of them is "wrong", 
even though both are giving the right answers to the precision with 
which they can be measured. And QED at least has been measured and 
matches predictions to something like 15 decimal places, which is an 
incredible precision.

Two - figuring out the combination might lead to all kinds of new 
discoveries. Just as an example, in 1890 or so, people thought they knew 
all about how light worked, and so on, except for one or two little 
anomalies, like black-body radiation and the photoelectric effect at low 
light levels. It took a whole new shift to quantum calculations to be 
able to understand those effects. That resulted in lasers, 
semiconductors, understanding genetics at the individual protein level, 
and so on.

If you can unify the operations of gravity and quantum interactions, you 
might be able to make electrogravitics, anti-gravity, gravity-powered 
light bulbs, stuff like that. Who knows? If you could get quantum 
miracles(*) to work reliably over space-like distances, you could get 
teleportation, time travel, stuff like that.

Plus, it might explain *why* quantum stuff is random, and whether 
there's any underlying unmeasurable rules, and so on, even if you can't 
manipulate it.


(*) AKA very low probability quantum teleportation events, like in 
tunnel diodes only long distances.
-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

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