Posted on 10/23/2003 1:56:32 PM PDT by LibWhacker
CLEVELAND - (KRT) - The day may come, some cosmologists fear, when they'd be better off as cosmetologists.
You know the difference, of course. Cosmetologists are experts at makeup. Cosmologists are experts at making up stories about the universe.
For many decades, at least, cosmologists couldn't do much more than make up stories. After the birth of scientific cosmology early in the last century, cosmologists based their theories on next to nothing, other than Einstein's equations for gravity and the observation that the universe seemed to be expanding.
In the mid-1960s, though, radiotelescopes detected a faint glow of radiation in space, left over from the big bang that got the universe going. And in the last decade or so, advanced instruments have produced a bonanza of data from studying that radiation. Combined with the Hubble Telescope's views of exploding stars and various other sources of interstellar intelligence, those measurements have allowed cosmologists to give their description of the universe a total makeover.
Cosmologists now say, for example, that the universe is not only expanding, but it is getting bigger at an ever faster rate. That's because it contains a mysterious form of repulsive "dark energy" that causes the expansion to accelerate. And cosmologists now know roughly how fast the universe is expanding, how old it is (approaching 14 billion years), and they know that space on average has pretty much a "flat" geometry – meaning that light rays travel in straight lines. (Don't laugh – space could have been curved, you know.)
So you'd think that all cosmologists would be joyous, and many do agree that their field is experiencing a "golden age." But others warn that they may pretty soon be forced to retire, as all the new knowledge has failed to answer many critical questions. In particular, the vast bulk of the universe's makeup remains unidentified.
"We don't know anything about the nature of 95 percent of the universe," said Wendy Freedman, of the Carnegie Observatories in Pasadena, Calif., at a recent cosmology conference in Cleveland.
Sure, astronomers know that about two-thirds of the universe's matter-energy content is the peculiar dark energy. But they don't know what it is. It could be a constant-strength, never-changing residual energy in the vacuum, or it could be some intangible, evolving fluid that strengthens or weakens as the universe ages.
"It's really clear that we don't understand where the dark energy is coming from," said astrophysicist Neta Bahcall of Princeton University. "The answer will come from a better understanding of physics."
Answers to other questions may require better theories from physics, too, said Max Tegmark of the University of Pennsylvania. "I think we need new physics for just about everything," he said.
For instance, cosmologists clamoring for clues to the dark energy's identity haven't yet solved an even older mystery, the identity of most of the universe's matter. About a third of the universe's mass-energy budget is "dark" matter, some alien form unlike the ordinary proton-and-neutron stuff making up everything on Earth. Theorists have proposed that unconventional matter made of "superparticles" is responsible for the unseen dark matter (which is detected by the gravity it exerts on visible matter). But searches for superparticles in atom smashers have so far not succeeded.
Now, it may just be that physicists need bigger and better atom smashers (aka particle accelerators), as MIT physicist Frank Wilczek advocated at the Cleveland meeting, held at Case Western Reserve University. (His favorite dark matter candidate is another particle, called the axion.) And the CERN laboratory near Geneva plans to bring a new accelerator on line in a few years.
But if it too fails to find superparticles, the dark matter's identity will become an even greater mystery. Explaining it may require more radical theories, including some that include more dimensions of space than the ordinary three, or even parallel universes.
Perhaps, some scientists seriously suggest, the visible universe is just one of many, residing next to each other in a higher dimension the way a book contains many parallel pages. What seems to be exotic dark matter may turn out merely to be ordinary matter on a neighboring parallel universe-page, transmitting its gravity but not any light.
"I am personally intrigued by the concept of extra dimensions on cosmological scales," said Stanford University physicist Blas Cabrera, a leader in the search for superparticles. Perhaps, he said, "we are looking foolishly for particles that don't exist, and it is normal matter in a parallel universe."
In any event, a real problem arises if dark matter searches continue to fail and efforts to identify the dark energy can't distinguish among the various possibilities. Cosmologists may find themselves with no place to go for the answers they still seek.
But Carnegie's Dr. Freedman offered some hope. There are many new projects in the works to gather more refined observations of the heavens. And some may turn up paths to cosmic knowledge that elude the dead ends many cosmologists now fear.
"I'm going to be surprised," Dr. Freedman said, "if there are no surprises."
D=E x T^2
Where:
D=the darkness of the energy
E= the measureable anti-gravitational strength of the energy
T= age of universe
So stated with Christian Certitude. Where are the young, radical philosophers gone? Berkeley, sure, but not all. Some are going back to the point Descartes made his fateful decision to base all on a reality of mathematical logic and geometrical physics. Go back to that crossroads and look for the other road, the one overlooked, a pure science not phenomenalism, not psychologism, not geometrism. Some shubbery might need pruning to see the road: it's an unused road.
you can't write a paragraph like that without writing 3 more paragraphs explaining what you mean by that :-).
Alan Guth needs wider recognition. And like somebody said on FR a few days ago, dark energy/dark matter may be the aether of our day.
Can someone give an armchair physics explaination of "dark energy". I understand that dark matter is hypothesized in order to explain the fact that the amount of visible matter doesn't seem to account for certain gravitationally-related phenomenon [In fact, there was an article around here just the other day concerning this]. But, what is the deal with "dark energy?" This isn't the quantum foam thing, where energy supposedly appears and disappears more or less at random out of nothing, is it?
Okay, I got off my a$$ and did a search. Plenty of info on dark energy.
Equating "energy" to "gravity" doesn't make much sense too me. If it is truly a repulsive force (in which case they should have called it something like "dark gravity" or URF, Unknown Repulsive Force) then what does it act on? What does it push? Normal matter? Dark Matter? The "fabric" of space-time? Or is it really just another Einsteinian Comsmological Constant, plucked out of thin air to explain the unexplained.
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