Dark Energy Confirmed

bill_mcgonigle writes "By correlating the results of the Sloan Digital Sky Survey and the Wilkinson Microwave Anisotropy Probe, astronomers have confirmed the existence of dark energy. While gravity attracts, dark energy repels, so by comparing the positions of millions of galaxies and their red-shifts with the temperature map of the early universe, evidence was found for dark energy on the scale of 100 million light years. "Dark energy, whatever it is, is something that is not attracted by gravity" said David Spergel, a Princeton University cosmologist and a member of the WMAP science team. "We are finding that most of the stuff in our universe is abnormal in that it is gravitationally repulsive rather than gravitationally attractive," said Albert Stebbins of the Fermi National Accelerator Laboratory. The universe is expanding at an accelerating rate, a switch that happened about 6.3 billion years ago, before which the expansion was decelerating."

Comments

Occam's razor

[ka9dgx]

Rather than assuming some bizarre physics of gravitons where they pull something they ram into, why not take a simpler approach and assume that they push things along, just like a baseball and the milk bottle at the faire?

The earth stops some of them passing through, and thus the ones from above us push us down. All the standard laws of physics still work on the local level, and nobody has to get a migrane trying to wrap their heads around weird concepts.

This is much simpler than "dark energy"... the farther you are from the source (or field) of gravitons (?? I have no idea where they come from), the less the "gravitational constant" appears to be.

--Mike--

Re:Occam's razor

[GeoGreg]

The whole trick here will be to fit all the observations together into a consistent model. People have been trying for a long time now to reconcile general relativity (i.e., the concept that gravity is equivalent to warped space-time) with quantum mechanics. Nobody has yet done it, and dark energy and dark matter seem to be bringing up more problems. My semi-educated guess is that significant new physics will be required to reconcile everything. It might be revolutionary on the same scale as Einstein, Bohr, etc. were. It may turn out that relativity is a special case of the "new physics", just as Newtonian gravity is a special case of general relativity. Maybe, for example, the speed of light is not quite as constant as we think it is. I don't know if that's true, but I feel that's the sort of paradigm shift that might be required.

Re:Occam's razor

[ka9dgx]

Ok, I'm mystified by the /. rating system sometimes myself.

I understand electromagnetic polarity, opposites attracting, etc... I don't want to play with the physics of that right now... just those darned unipolar gravitons.

If you assume a very high flux of gravitons, all with a very low mass (or energy), and a low probability of interacting with a given unit of mass, the following conditions start to fall out of the math:

• a sufficiently dense mass will stop a very small, but consistent fraction of the gravitons that pass through it.
• If the flux of gravitons is uniform from all directions, the net effect on a single mass is zero.
• A mass in a uniform graviton flux will create a graviton shadow in which there will be a gradient of less gravitons nearer the mass.
• Two masses near each other will be effected by the graviton shadown with a result just like that of Mr Newton, except that "Big G" isn't really a constant, just a constant times the overall ambient graviton flux.
• The push of the two objects together is from an EXTERNAL source of gravitons. (Left over from the big bang?)

Prediction: If a material is found that shields gravity... it will effect materials in an unorthodox manner in the eyes of physicists as follows:

• A mass below a said "shield" will be lighter. If you could stop 100% of gravitons in their tracks, you'd have a very effective artificial black hole.
• A mass above the shield will get heavier.
• The material will have the appearance of having a great deal of mass, which might be greatly different than it's inertial mass.
• It'll be hard to find, because it'll just appear to be a dense material. A material based on an interference filter might be the only possible hope for an efficient gravity stop.

I haven't done tons of simulations, but I'd be willing to do them if someone were to take the idea seriously, and make it worth my time.

--Mike--

Dark matter vs. our matter

[tsuliga]

When I first studied cosmology, I wanted the theories to work out so our universe would be a series of Big Bangs that would go on infinitely. This would mean we were all part of a never ending series of events that can lead to sentient life. Now that Dark Matter is gaining acceptence, it changes things.

If the Big Bang was a one time event, and the Universe will expand forever then the question is how did this first and only Big Bang happen. What forces were at work prior to the Big Bang?

While this knowledge won't have a meterial effect on me, as I age, it's nice to know things of such a grand scale especially if the knowledge is confirmed to be true.

I hope physicists continue to make progress on Dark Matter and that Slashdot keeps posting such articles. Although I would prefer it to be on the main page.

Re:Dark matter vs. our matter

[stevelinton]

What forces were at work prior to the Big Bang?

"Prior to the big bang" is almost exactly as meaningful as "North of the North pole". The 3+1 dimensional coordinate system (3 space, 1 time) that can be neatly spplied to events in most regions of the universe fails in the presence of too much energy, as in a black hole, or at the big bang.

Refuted by Feynman

[Anonymous Coward]

Feynman discusses, and refutes, a similar theory of gravity in The Character of Physical Law .

If I recall correctly it is in the chapter where he establishes why physical law must be expressed in terms of equations. Common sense ideas like the one you mentioned are tempting, but don't seem to fit the facts we know.