Wednesday, June 4, 2008

Dark thoughts

This column by Brian Greene ran on Sunday June 1, 2008 in the NY Times and was among the most popular stories for several days. It’s in praise of science as a way of understanding the world. http://www.nytimes.com/2008/06/01/opinion/01greene.html.  Greene’s main point was this: 
The reason science really matters is that science is a way of life. Science is a perspective. Science is the process that takes us from confusion to understanding in a manner that’s precise, predictive and reliable — a transformation, for those lucky enough to experience it, that is empowering and emotional. To be able to think through and grasp explanations — for everything from why the sky is blue to how life formed on earth — not because they are declared dogma but rather because they reveal patterns confirmed by experiment and observation, is one of the most precious of human experiences.
 I was thinking of that in light of Yi-Fu Tuan’s comments (see May 21 post) that biologists see the world as messy and without meaning, perhaps from peering at all that junk DNA, while physicists are led to see the world as a magical creation of some kind of god because of the marvelously beautiful mathematical formulae that seem to inform its structure with an inner order. Then I read this in Tuesday’s Times and now I don’t know what to think:
Dark, Perhaps Forever
By DENNIS OVERBYE

Although cosmologists have adopted a cute name, dark energy, for whatever is driving this apparently antigravitational behavior on the part of the universe, nobody claims to understand why it is happening, or its implications for the future of the universe and of the life within it, despite thousands of learned papers, scores of conferences and millions of dollars’ worth of telescope time. It has led some cosmologists to the verge of abandoning their fondest dream: a theory that can account for the universe and everything about it in a single breath.

Through myriad techniques and observations, cosmologists have recently arrived, after decades of strife, at a robust but dark consensus regarding a cosmos in which stars and galaxies, as well as the humans who gawk at them, amount to barely more than a disputatious froth. It was born 13.7 billion years ago in the Big Bang. By weight it is 4 percent atoms and 22 percent so-called dark matter of unknown identity — perhaps elementary particles that will be discovered at the Large Hadron Collider starting up outside Geneva this year. That leaves 74 percent for the weight of whatever began causing the cosmos to accelerate about five billion years ago.

As far as astronomers can tell, there is no relation between dark matter, the particles, and dark energy other than the name, but you never know. Some physicists are even willing to burn down their old sainted Einstein and revise his theory of gravity, general relativity, to make the cosmic discrepancies go away. There is in fact a simple explanation for the dark energy, Dr. Witten pointed out, one whose tangled history goes all the way back to Einstein, but it is also the most troubling.

“Dark energy has the somewhat unusual property that it was embarrassing before it was discovered,” he said.

In 1917, Einstein invented a fudge factor known as the cosmological constant, a sort of cosmic repulsion to balance gravity and keep the universe in balance. He abandoned his constant when the universe was discovered to be expanding, but quantum physics resurrected it by showing that empty space should be foaming with energy that had the properties of Einstein’s constant.

“Before the discovery of the dark energy, quantum physicists tended to assume that the ‘vacuum’ we live in has some deep meaning that reflects nature’s deepest secrets,” Dr. Witten said. But if ours is only one of a zillion in a haystack, there is nothing special about it, no secret to be found.
You can read all about it at http://www.nytimes.com/2008/06/03/science/03dark.html?

What do you think? Dark or not?

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