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Wednesday, December 16, 2009

Dark Matter, Dark Energy an Illusion?

I once said, “when I was in school, there was no dark matter and no dark energy”.  I was correctly corrected on this, because dark matter and dark energy exist independent of whether we know about them or not.

Maybe.  According to some recent theorizing, dark matter and dark energy may not exist after all:

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http://www.scientificamerican.com/article.cfm?id=splitting-time-from-space
discusses a gravitational theory from Petr Horava, a physicist at the University of California, Berkeley. If this theory proves to be more correct, then dark matter and dark energy MAY turn out not to be there.

"Horava gravity may also create the “illusion of dark matter,” says cosmologist Shinji Mukohyama of Tokyo University. In the September Physical Review D, he explains that in certain circumstances Horava’s graviton fluctuates as it interacts with normal matter, making gravity pull a bit more strongly than expected in general relativity. The effect could make galaxies appear to contain more matter than can be seen.”

“If that’s not enough, cosmologist Mu-In Park of Chonbuk National University in South Korea believes that Horava gravity may also be behind the accelerated expansion of the universe, currently attributed to a mysterious dark energy. One of the leading explanations for its origin is that empty space contains some intrinsic energy that pushes the universe outward. This intrinsic energy cannot be accounted for by general relativity but pops naturally out of the equations of Horava gravity, according to Park."

I think it's fascinating that dark energy and dark matter went from being unknown to possibly most of the universe and now possibly to nonexistent. I wish I was 10 again, and could cram all the math into my head that could possibly go in there, just to have a shot at dealing with problems like this.

 [Horava's name has been converted to standard English characters.]