Posted on 02/21/2003 9:34:03 AM PST by dead
Einstein supposed the universe was beautiful. But Graham Farmelo reports that new evidence points the other way.
Could it be that the universe is fundamentally ugly? For 90 years, most astronomers believed that the simplest, most beautiful version of Einstein's theory of gravity describes how the universe evolves.
Four years ago, however, a group of astronomers astonished the world by showing that, according to new data, nature does not adopt the most beautiful version of the theory but prefers an ugly variant. Then last week NASA announced stunning new observations that lent strong support to the notion that the universe is not beautiful in the way Einstein supposed. Soon, other astronomers will contribute new evidence on the way the universe is built. Will beauty prevail?
It was Einstein who first pointed out that it was logically possible to make an unsightly addition to his gorgeous 1915 theory of gravity. He even used this flexibility to tinker with his theory by introducing something he called the cosmological constant. Always uneasy about the presence of this constant in his theory, he hoped that its value would be zero. Einstein wrote in 1947 to the Belgian big bang pioneer Georges-Henri Lemaitre: "I am unable to believe that such an ugly thing should be realised in nature."
For once, it appears that Einstein's intuition was wrong. The unwanted constant really does seem to be needed if Einstein's theory is to describe nature. The first experimental demonstration that the cosmological constant is not zero was announced four years ago by a team of astronomers led by Brian Schmidt and his former research supervisor Robert Kirshner, of the Harvard-Smithsonian Centre for Astrophysics. Their findings were based on studies of supernovae, exploding stars that disgorge their matter into outer space.
But the data had large uncertainties and many astronomers were sceptical. "At first, I thought this must be wrong," Kirshner says. "After all, Einstein thought the cosmological constant was his greatest blunder, and he was pretty smart. But now, five years later, I'd bet my bull terrier!"
Then last week new evidence was announced in the US. This did not come from astronomers studying supernovae but from a satellite, located on the other side of the moon. This satellite, MAP, has been taking data that examine the microwave radiation that pervades the universe.
By studying the temperature of this background radiation, the group found that the universe is, in the jargon of Einstein's theory, flat. This means that parallel lines will never meet, even over cosmically large distances. This flatness makes it relatively easy to account for the different types of matter in the universe.
By comparing this satellite data with other astronomical obser- vations, it is now possible to pin down the relative amounts of the different types of matter in the universe. It turns out that about 23 per cent of the universe is made of mysterious particles of dark matter, stuff that doesn't shine or reflect light, but whose existence is evident from the forces it exerts on distant galaxies.
Only about 4 per cent of the universe is made of the common-or-garden atoms that make up all the matter on our planet. So 73per cent of the universe should be made of a mysterious material (unhelpfully dubbed dark energy) that somehow provides a negative pressure that drives the expansion of the universe.
Astronomer David Spergel says: "Remarkably, all the evidence from different cosmological sources now fits together, giving a simple description of the universe from its origins in the big bang 137 billion years ago."
But could this widely accepted picture be built on sand and the cosmological constant be zero after all, as Einstein hoped? Several experiments are now under way to check this, once and for all.
The satellite has another three years worth of data to collect. And Kirshner's former research student Adam Reiss is leading a team that is using a new camera on the Hubble Space Telescope to take repeated images of a typical spot in the sky every 40 days.
The hope is to find more distant supernovae than can be detected from telescopes on the ground. If the current picture for cosmic acceleration is correct, these should be so distant that they will show the effects of cosmic slowing down, before the dark energy gained the upper hand.
Kirshner says: "It's like a tug-of-war. First we expect the weight of dark matter to slow the universe, but as the universe expands, the dark energy gets the upper hand, so we expect acceleration to take over at later times. If we see that change, from slowing down to acceleration, it will clinch the case."
If later observations don't wreck the current consensus, this will become a classic case of what the biologist T.H Huxley described 130 years ago as the great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.
Telegraph, London
We tend to think things are beautiful when they are symmetrical, harmonious, appealing.
Perhaps God has a different sense of what is "beautiful".
Would aliens evolving on a world which never had rainbows think rainbows were beautiful once they saw them on Earth?
--Boris
(And before someone whips out Occam's Razor, let me remind them that William of Occam would have been entirely in agreement with the above, having been a Christian theist himself. He would have observed that when the Creator has given us information about His creation, to willfully disregard that information in an attempt to construct a more "simple" explanation is an illegitmate application of his "Razor.")
Disbelieve if you will, but a non-theistic uniformitarian paradigm is every bit as much a leap of faith as is Judeo-Christian Theistic creation. I would argue that it is even more of a leap of faith.
That seems to presume that the acceleration of the Big Bang has long been over. Perhaps we are nowhere near the end of the original acceleration and expansion of the "Bang". If the dark matter exerts an influence (gravitationally) on the rest of "known" matter, it may still be accelerating.
Many physics theories presume a cosmic maturity that may not, at present, exist. "We" may be in the middle of the "Bang".
"There is another theory which states that this has already happened."
--- Douglas Adams The Hitchhiker's Guide to the Galaxy
The universe is the way it is, and not how we would wish it to be.
This did not come from astronomers studying supernovae but from a satellite, located on the other side of the moon.
Wrong. It is located at the Earth's L2 point with respect to the sun, not the moon's L2 point with respect to the Earth:
Astronomer David Spergel says: "Remarkably, all the evidence from different cosmological sources now fits together, giving a simple description of the universe from its origins in the big bang 137 billion years ago."
Typo, should be 13.7 billion years.
"Think of it this way," explains Bock. "If we were to balance on a large ball, we would certainly feel the curvature beneath our feet. Expand that ball to the size of the Earth, and we experience that space as flat. Now think about blowing up that ball to a cosmic scale, and you can imagine how inflation would vastly flatten the visible universe."
I've never understood why infaltion models imply anything other than locally flat curvature. Can you recommend any technical readings on this?
I'll take a stab at that, although I'll defer to "Physicist" if I don't get this quite right.....
Inflation is constrained by Conservation of Energy; as space inflates, the volume of space permeated by gravitational fields increases. Since gravitational fields have a NEGATIVE energy associated with them (ask "Physicist" for his delightful explanation of this fact), the amount of negative energy in the Universe increases as space is "inflated." Conservation of Energy REQUIRES the production of EXACTLY the amount of positive matter/energy needed to offset the increase in negative energy, such that the net total is always zero (otherwise, it would violate the Conservation of Energy.)
But that's exactly what flat space is: the gravitational fields are counterbalanced by precisesly the amount of matter/positive energy needed to cancel out the negative gravitational energy. Thus, the Inflationary process has no choice but to yield a Universe that is spatially flat, because Conservation of Energy won't permit anything BUT that from happening.
Just for fun, I'll go one step further: The Law of Conservation of Energy is a consequence of the temporal homogeneity of the Universe (physical properties are invariant under temporal transformation.) So, if Inflationary Cosmology is correct, then it follows that the flatness of space is a consequence of the temporal homogeneity of the Universe...... I think.
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