The Warring States of NPF - "Good bye Dark Matter, Hello General Relativity?"

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"Good bye Dark Matter, Hello General Relativity?"

http://www.cerncourier.com/main/article/45/8/8

Quote:

General relativity versus exotic dark matter

Determinations of the rotation speed of stars in galaxies (galactic rotation curves) based on the assumption that Newtonian gravity is a good approximation have led to the inference that a large amount of dark matter must be present - more than can be accounted for by non-luminous baryonic matter. While there are plenty of attractive theoretical candidates for the additional dark matter, such as a lightest supersymmetric particle (LSP), it is also interesting to look into the details of the calculations that suggest the need for such exotica. Now F I Cooperstock and S Tieu of the University of Victoria have reworked the problem using general relativity in place of Newtonian gravity, and they find no need to assume the existence of a halo of exotic dark matter to fit the observed rotation curves.

This is because even for weak fields and slow speeds, well-known nonlinearities change the character of the solution dramatically. The success of Newtonian mechanics in situations like our solar system can be traced to the fact that in this case the planets are basically "test particles", which do not contribute significantly to the overall field. However, in a galaxy this approximation is not a good one - all the rotating matter is also the source of the gravitational field in which everything rotates.

Diiiiscuss.

Discuss how? Give us some direction, yo. Frankly not being a scientist or nuclear physicist or atomic whatthehellicist I have little idea what the gist of this is. Please start discussion topics with more than "[Posted article] Discuss!"

Interesting... I never really put a whole Hell of a lot of stock in the Dark Matter theory, personally. I can't really say why, but it always just sort of rubbed me the wrong way, you know? It always seemed rather like the "here there be monsters" solution. I guess it's not terribly surprising that scientists would rely on the idea of some unknown sort of crap flaoting around wehre we can't detect it rather than admit that they might have just worked the problem wrong - but I still find it quite refreshing to see someone looking for the simple (well, simpler) explanation. Of course Raltivity is not proven fact, either, but to my eyes, at least, it seem a bit more rational than dark Matter.

Sorry bout that shiney: I only know a little about this, and I knew there were many people onthis board who debated topics similar to this at great length, so I was hoping they could give more of a springboard.

Relativity in general and specific has been expirementally proven just about as well as Newtons Laws. The proof comes in every day from particles traveling farther than they should with their given half-lifes and atomic cloaks running slower at high speeds on a plane and faster in orbit due to the lack of gravity. Only two predictions remain untested for general relativity and those are frame dragging and gravity waves and we should have answers to them in a few years.

Now there are several types of dark matter and energy. This type was introduced to explain the shape of galaxies but the other stuff that has been used to explain the motion of galaxies and the apparant shape of the universe is still there. The good news is we have a pretty good idea what this energy keeping the universe more or less flat. We like to call it the Zero point field. Of course I'd be interested to know if the calculation of total energy in the Zero point field has increased now that this other darkmatter isn't needed. After all it was taken into account as being there when the amount of matter still needed to make the universe flat and expanding was calculated.

I know a website that attempts to disprove the theory of dark matter, but it is kind of on the religious side. But, the author seems to be very educated in his field. I have his book. It's purpose is to provide logical explainations to things like this.

Would it be okay for me to link it? The entire book is archived on the site, but you'd only have to read one four-five page section on the dark matter topic.

Upheld in testing is not remotely the same as proving... That's why so much of science is the Theory of This and the Theory of That... not to mention the Theory of the Other Thing. It's incredibly hard to prove something like that scientifically true, although you can have it be generally accepted. Scientists tend to be realists enough to know that many theories just cannot be proven, and resign themselves to that, working from theory as though it were law because it constantly applies.

Well from that stance you can't call Newtons laws laws either. A certain amount of skeptacism is healthy but at a certain point you have to have a little faith. If every expierment ever done matches with the theory and there's essentally nothing left to test its a good chance your right. There is very nearly as much evidence for Relativity as for Newtons laws. The real difference is that Newtons laws or more intuative and easier to understand. Plus it relies on more basic everyday expierence.

But really the only way to prove something is to prove it wrong, at least from a scientific standpoint. Which means it's impossible to absolutely 100% without any lose ends prove something. So you can go around spouting how this and that are just a theory but like it or not you have to work inside them most of the time. There are a few with little to no proof and those you should avoid. But theories that have beat every critic for over 50 years and have had near every prediction varified might as well be considered proved. That's as close as you're ever going to get.

Also it's hard to talk for a segment of a population, I've done this myself and realize how impossible it is. Even if you're part of that segment it's really hard to know what all your peers are thinking. Even more so when there are at least several million worldwide.

Quote:

But theories that have beat every critic for over 50 years and have had near every prediction varified might as well be considered proved. That's as close as you're ever going to get.

I was disscussing with a friend of mine how we could essentially be under a fabricated system of understanding - How the scientific laws we use might in some ways be arbitrary designations.

The only way to illustrate this I can think of would go something like.

'Law' 1 is generally accepted, but not nessecerily true. 'Law' 2 works becuase it has been developed from 'Law' 1. 'Law' 3 works in conjunction with 'Law's 1 & 2, etc... Later, 'Law' 1 is proven wrong, and all studies and designations and measurments from 1-3 are thrown out as innaccurate.

Of course, its much more detailed than that in real life, and the studies can generally be verified to a satisfying degree, but its an interesting 'what if'.

Anyway, I'd very much like to get the gist of Locke's posted article - does it mean that dark matter with lots of gravity doesn't nessecerily exisist or what? I'm lost.

It means that if these guys are correct, then there's no need for Dark Matter to exist. Newtonian laws describe how gravity works very accurately in a macroscopic setting. But they don't work at all in the microscopic world. Newtonian formulae just don't make sense once you get to subatomic particles. It seems they also tend to break down in a, let's say, super-macroscopic setting.

Neither of these limitations should be too shocking since Newton could only make theories and formulas to describe his observable world. That world consisted of the Earth and a few planets. Thanks to a few hundred years of scientific progress, we've expanded the observable world far beyond anything Newton could've imagined in his day. It'd certainly be convenient of his theories could extend to our new horizons, but it should come to no surprise that an architect's tools, training, and experience aren't well suited for making jet fighters.

Enter Einstein and Quantum Mechanics for super-macroscopic and microscopic settings respectively. If you plug a QM formula in place of Newtonian ones, suddenly you can predict subatomic behavior. Similarly, these guys have plugged Einstein's work in place of Newton's and suddenly we've got a model for the universe that doesn't need Dark Matter.

Frankly, any scientist who ever took Dark Matter seriously needed to have his head (and credentials) examined. I know this development hasn't disproven Dark Matter, but I've always thought the idea that 95%+ of the universe's mass is supposed to be made up of a material that is impossible to detect is far more ludicrous than the idea that, maybe, we didn't have the calculations quite right in the first place. It's such absurd hubris.

"Hm, according to our theory here, the universe can't possibly work. Maybe we should rethink our approach."

"No, no. It's the universe that's wrong."

"What?"

"Hear me out. There could be, I don't know, loads of extra matter out there that we've never detected."

"Why haven't we?"

"Because it's impossible to detect directly!"

"Why?"

"I told you. It just is. See? It proves itself. I'm a genius."

And just so I don't seem like a Johnny McIt'sSoObviousNowThatSomeoneElseFiguredItOut, I was mocking Dark Matter's feasibility years ago in my book. So nya!