Thursday, October 2, 2008

Dark energy, go gently into that good night ... and take the "Copernican Principle" with you ... ?

In "Scientists: Earth May Exist in Giant Cosmic Bubble" (October 01, 2008) Clara Moskowitz of Fox News reports,
Earth may be trapped in an abnormal bubble of space-time that is particularly devoid of matter.
Excuse me, I'm sure I've heard something like that before somewhere:
And the earth was without form, and void
It wasn't in a science class, but hey.

The concept of "dark energy" - a mysterious force no one understands - was developed to explain the universe today. But many scientists would like to get rid of dark energy as a concept because it is mysterious, which is not good for business.

And, as Moskowitz notes,
If we were in an unusually sparse area of the universe, then things could look farther away than they really are and there would be no need to rely on dark energy as an explanation for certain astronomical observations.
Ah, but, (diabolical music) - Cue The Devil:
One problem with the void idea is that it negates a principle that has reigned in astronomy for more than 450 years: namely, that our place in the universe isn't special.

When Nicholas Copernicus argued that it made much more sense for the Earth to be revolving around the sun than vice versa, it revolutionized science.

Since then, most theories have to pass the Copernican test. If they require our planet to be unique, or our position to be exalted, the ideas often seem unlikely.

"This idea that we live in a void would really be a statement that we live in a special place," Clifton told "The regular cosmological model is based on the idea that where we live is a typical place in the universe. This would be a contradiction to the Copernican principle."
Trouble is, the "Copernican Principle" was fashionable rot popularized by pop astronomer Carl Sagan, in part to promote theories about space aliens that supported science kitsch like the Drake Equation (= calculate your own likelihood of meeting a space alien).

It never had anything to do with Copernicus who would certainly have disowned it.

Earth could very well be in a giant bubble. We already know that it is in a very unusual position.

Anyway, the Joint Dark Energy Mission of NASA and the U.S. Department of Energy hopes to test the bubble thing in 2014 or 2015. They ask, Do we really observe galaxies rapidly accelerating away from us or do we observe objects being distorted in a void because, in yet another way, we are in an unusual position? It could look the same.

They hope to discover that the universe is really accelerating.

In Ars Technica, Matt Ford notes
This work represents a major departure from the currently accepted model of the universe, and it rejects a long-held tenet of astronomy and cosmology. Using the currently available data, the authors were unable to show that their model is closer to reality than the commonly accepted CDM description of the universe. Perhaps one of the biggest repercussions of this work, if correct, would be that we could no longer rely on our local measurements to describe the universe as a whole.
So the universe may not turn out to be what we expect? We shall see.

And see also:

"Privileged planet" astronomer Guillermo Gonzalez: Dissing St. Carl Sagan in his own church

Study: Sun not special, therefore alien life should be common?