Posted on 02/21/2008 7:47:47 PM PST by NormsRevenge
Which means, you don't know, either, and thus your confidently expressed opinion about the non-existence of "dark matter" is rather presumptuous.
Nope. Dark matter started as a mathematical construct, and no direct evidence has shown it to be anything else.
I would venture to say that the fact of something causing gravitational lensing is sufficient to say that whatever it is, is a bit more than a "mathematical construct."
Nope. For one thing, our galaxy isn’t headed in the direction of that supposed “dark matter.”
It may be lensing, but it’s just a camera lens, not gravity from an unknown source pulling objects toward it.
True, but the whole thing could just go OBAMA, just like THAT...NOT!
Sigh. Well, I guess you must be much smarter and more capable than the fellows doing the math for this study....
Sigh...the lack of gravitational pull on physical objects is a fatal flaw. Whether I’m smarter than them or not, they’ve got to deal with such demonstrable flaws.
Until they do (which they may not), dark matter can only be accurately stated to be a fictional mathematical construct useful for modeling.
No. Like neutrinos from the Sun, the particles responsible for dark matter are moving at close to the speed of light. ~5*1013 solar neutrinos pass though your body every second and you were completely unaware of that.
1. Galileo might be taken as the initiator of this unfortunate tendency to reduce everyting to math.
2. Maybe it has, but since mathematical reductionism is the law, who would know.
It is bent space. In order for space to be curved, and energy density must be responsible for that curvature. Since no other interaction can be observed in the region, the particles responsible for the energy density must be non, or very weakly interacting.
"No."
"Right there! That's it...that's the stuff! Dark M-A-T-T-E-R!"
"I don' see nuthin'."
"Right! That's how we knows it's there!"
"Hmm...I should see somethin' shouldn' I?"
No, no, no! It's D-A-R-K Matter! Now be careful not to stumble over it in the light..."
To give you an idea of how idiotic the claim really is, consider the nature of the emptiness of space. By pure chance, there are about as many inches in a mile as there are astronomical units ( AUs) in a light year. If you make that your scale, i.e. one inch equals one AU, then our solar system is about a yard in diameter, the sun is about the diameter of a human hair, the Earth is an inch from the sun, and the nearest other star is over four miles away.
Now, obviously, there is no way in hell gravity can hold two dust motes together from four miles distance. Nonetheless the idiots who believe in this business claim that all that is needed is a 20-fold increase in mass, via "dark matter".
Nonetheless and equally obviously, that would not work any better; it amounts to a claim that if you put a dust mote every fifth of a mile over four miles distance, gravity WILL hold the thing all together. Bull****. The distance between our sun and Alpha Centauri is pretty typical of stellar distances and even in dense star clusters which glow in clusters, the individual distances between stars are relatively similar to the sun-AlphaCentauri distance.
The basic hard, cold reality is that EM forces which are 40 orders of magnitude more powerful than gravity hold galaxies together, and gravity does not. Once you understand that, you no longer need "dark matter(TM)"...
That's right, but they are part of the dark matter which comprises about 25% of the critical energy density of the universe.
"Now, obviously, there is no way in hell gravity can hold two dust motes together from four miles distance."
No, not obviously. There is a gravitational interaction and there will be dynamics. What the dynamics looks like will depend on the particulars.
"The basic hard, cold reality is that EM forces which are 40 orders of magnitude more powerful than gravity hold galaxies together, and gravity does not."
That's not supported by any evidence and it's ridiculous. The solar system is governed by an approximate inverse square law, not an inverse cube law, that would occur if dipolar and higher dielectric forces were in play.
"you no longer need "dark matter""
The rotational dynamics of galaxies indicate a constant angular velocity with radial distance from the center. Given that the galactic binding energy is contained in the gravitational field, the presence of dark matter is clearly indicated.
The fact that the total energy of the universe is zero means the positive energy contained in the various particles is balanced by the negative energy of the gravitational field.
No, not obviously. There is a gravitational interaction and there will be dynamics. What the dynamics looks like will depend on the particulars.
Mooooooo, plop, plop.......
Dark matter is really more than a theory or a mathematical construct — it is a reasonable explanation for observed phenomenon based on what is known about physics. From my reading of the matter of dark matter ;O> I’m betting that the evidence it does exist is solid, the controversy is over what it exactly is. At any rate, I have no grudge against dark matter :O> and I hope the article below is correct because I love it when the mysteries of the universe and the big bang are probed and understood as far as possible and all the hard work done by scientists has a successful outcome.
http://news.bbc.co.uk/2/hi/science/nature/6235751.stm
“With the aid of 7,000 separate measurements, the researchers have been able to establish that the galaxies contain about 400 times the amount of dark matter as they do normal matter.”
Nope. Dark Matter is a mathematical fudge factor. Einstein, you see, said that our universe was static.
Hubble, however, observed that our universe was expanding at an ever increasing rate. This observation disproved Einstein, general relativity, and the Big Bang Theory...unless there was some unknown matter at the edges of the universe whose Gravity was causing the acceleration of all known galaxies.
By working backwards from Hubble’s observations, mathematicians were able to say how much “unkown matter” would be required to exist in the universe for Einstein and the Big Bang to both have a chance at being correct.
They called that fudge factor “dark matter” and then included it as “fact” in calculations based on Einstein’s general relativity formulas. Poof! Now there was an explanation (matter has gravity, after all) for why galaxies were speeding up as they headed toward the edges of the universe.
But where “dark matter” is inevitably inferred to exist, such as in the picture for this thread, mathematicians and scientists have a problem in that our known galaxies aren’t heading toward those areas of supposed “dark matter.”
This leaves “dark matter” as remaining still yet unproven (or more accurately: disproven by all known observations).
But since no one wants to claim that Einstein was wrong about general relativity (other than Hubble, who won fame, a space telescope, and caused much rewriting in Einsteinian work), everyone has to pretend that “dark matter” somehow still exists so that we can keep using the old formulas to explain why galaxies are speeding up.
This didn't come from that link. normal matter comprises ~4% and dark matter comprises ~23% of the critical energy density of the universe. Galaxies couldn't contain 400x mare dark, than normal matter.
Ah! Then it is a conspiracy of sorts. (Roll eyes and back slowly out of the thread.)
No, it just means that we don’t know why galaxies are speeding up.
“Dark matter” is a shot in the dark at that, but it isn’t faring well against evidence and observations.
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