Re: LIGO.
- From: cliff wright <c.c.wright@xxxxxxxxxxxxxxx>
- Date: Wed, 21 Feb 2007 12:09:55 +1300
Tom Roberts wrote:
cliff wright wrote:
Now we have a vast "zoo" of particles, despite valiant efforts to simplify things and can "see" out to a rerasonable sample of the universe, if the simple "Big Bang" theory is accepted.
We now need "missing mass" as WIMPS or MACHOS or something even more esoteric, "dark energy", mysterious anti-gravity forces and divers other "odds and sods" like cosmic strings.
Sorry if it offends you, but as a science historian this begins to remind me of Crystal Spheres and Epicycles and other pre Copernican
machinery.
Yes. There is currently a "crisis" [#] in theoretical physics, and has been one for many decades: the incompatibility between GR and quantum mechanics. And a large number of theorists are attempting to address this issue -- that's what string theory is all about (not to mention loop quantum gravity and ...).
[#] See Kuhn, _The_Structure_of_Scientific_Revolutions_.
IMO it is well past time that physics in particular took stock of the situation and re evaluated the "big picture" by giving more attention to
simplifying theories.
GR is quite clearly the "simplest" theory within its domain, for essentially any meaning of "simplest" based on a theory's foundations or concepts. This may come as a surprise, as GR it quite complicated to apply, but its theoretical foundations are quite simple: the equivalence principle, local Lorentz invariance, and coordinate independence.
My experience in science over 45 years has always been that real advances tend to come at the interface between disciplines rather than from those deeply centred in them.
Yes. The intersection between GR and QM is a hotbed....
As to " emotional reactions" to heterodox ideas well a year or two back a modified theory of gravity at very large distances was proposed which appeared to remove most of the "missing mass" problem. The reaction I saw from some physicists was practically a howl of rage.
Hmmm. My interpretation of that was not "rage" but incredulity -- surprise anyone would think it made sense. It is not science to "tweak" a theory with the sole purpose of making it agree with observations, and such theories are FAR more complicated than GR (even Newtonian mechanics is more complicated than GR, in this sense). IIRC such theories have as many free parameters as observations to fit, so it's no surprise they can fit them, but they don't "teach" anything -- what you get out is just what you put in.
Tom Roberts
Good Day Tom.
Well there we agree, there is indeed a crisis in Physics and ubfortunately it has gone on now for decades with very little resolution. Perhaps that is why so much esoterica keeps bubbling up in what looks like increasingly desperate attempts to salvage a coherent "world view" from the chaos.
The multi universe implications of some string theories I fine especially philosophically interesting but the only, very dubious test I have heard for any of this so far is an examination of the variations in the "cosmic background" radiation which looks to me neither very sensitive or inherently reliable.
GR is indeed the simplest available theory of "almost everything" to date but then we already know that GR does NOT apply in quantum mechanics and some of its predictions lead to far too many infinities for my taste. Here of course we run into the boundary (if any) between Philosophy and science.
No argument at all, about the interface between disciplines. I still reckon the whole problem about the "cold fusion" phenomenon was that chemists didn't fully understand Physics and vice versa.
Now here is where we do differ-
Historically science is full of what you describe as "tweaks".
Kepler did a lot of them with his laws of planeatary motion for example based on Tycho Brahe's observations.
In my day we called really bad tweaking "Cook's Constant".
In any case postulating invisible and almost undetectable matter and energy to fit the observations is EXACTLY what modern cosmology has done.
One poster pointed out about Gravitational lensing as a "proof" of the existence of "dark matter", but since this has proved completely undetectable except in so far as it saves the theory how is it in any way superior to a modification of Newtonian/Einsteinian gravity at extreme distances. Indeed "dark matter" has to be very selective in its location to have anything like the effects we observe.
I'm getting pretty sure in my old age that much of the problem stems from the very poor standard of science teaching these days. In my time (the 1950's) we did lots of hands on experimentation, I'm sure that we ended up with a far better grasp of the realities of science and experiment than modern students have.
Cliff Wright.
.
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