Theory Unifies Dark Matter and Dark Energy

In a bit of a shrug, as krakatoa calls it, the theory also seems to say "...and don't bother trying to confirm the existence of either of these around earth, because its very nature will prevent it from every showing itself."

I don't really understand it very well but it seems interesting as all hell. Possibly because the old idea of "ether" is being revived.

The two biggest mysteries in cosmology may be one. A new theory says that dark matter and dark energy could arise from a single dark fluid that permeates the whole universe. And this could mean Earth-based dark matter searches will come up empty.

Dark matter, as originally hypothesized, is extra hidden mass that astrophysicists calculate is necessary for holding together fast-turning galaxies. The most popular notion is that this matter is made of some yet-to-be-identified particle that has almost no interactions with light or ordinary matter. Yet it seems to be everywhere, acting as a scaffolding for galaxy clusters and the whole structure of the universe.

On the other hand, dark energy is needed to explain the more recently-discovered acceleration of the universe's expansion. It supposedly exists all throughout space, delivering a pressure that counteracts gravity.

It's counterintuitive that one substance could be both a gravitational anchor for galaxies and anti-gravity force for the universe. However, HongSheng Zhao of the University of St Andrews in Scotland claims that a fluid-like dark energy can act like dark matter when its density becomes high enough.

...

"[Our theory] involves positing a preferred time direction, in some sense a special time frame," Ferreira said. "It has the interesting effect of modifying Einstein's theory of general relativity."

The idea is similar to the "ether," an invisible medium that physicists once thought light waves travelled through. Einstein's relativity did away with the need for such a medium, but cosmologists have recently found that an ether-like substance can mimic dark matter.

The presence of such a substance changes the way gravity works. This is most noticeable in the distant outskirts of a galaxy, where the galaxy's gravitational pull would be expected to be small, but the ether makes it much stronger.

The ether "effectively softens space-time in regions of low [gravitational] acceleration making it more sensitive to the presence of mass than usual," Ferreira explained.

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Christian Boehmer from University College London thinks it "compelling" that Zhao's model can reproduce so much galaxy data.

posted by Ace at 01:56 PM

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