Posted on 08/09/2002 8:05:01 AM PDT by dead
If the speed of light can slow down, as new findings suggest, scientists may have to think again about some other laws of nature. John Webb writes.
Is it outrageous to ask whether the laws of nature have remained the same since the Big Bang created our universe about 14 billion years ago? The great British physicist, Paul Dirac, didn't think so when he suggested the idea in 1927. And he still thought that way when he lectured on the topic at the University of NSW in 1975.
However, the reasons for asking the same question today are very different and, according to most physicists, more compelling.
The holy grail of physics, for almost a century, has been to find an elegant theory describing all of the known forces found in nature. Today, we think these are gravity, electromagnetism, and two further forces holding the nuclei of atoms together (the strong and the weak force).
Though the strengths of these forces differ, and the distances over which they operate are different, many physicists have always believed that a unified description of them must be found. If not, the beauty and simplicity of fundamental physics are lost. Yet we know from many other striking examples in science that the right answer to a complex problem often turns out to have a satisfying simplicity to it. Albert Einstein was so convinced of this general principle that he unsuccessfully devoted the last 30 years his life to it.
The main contender today for such a theory (M-theory) requires adding extra dimensions to the ordinary "up-down, left-right, forward-backward". We cannot see or directly experience these extra dimensions because they are minute compared with our ordinary, 3D spatial dimensions - smaller than an atom.
In the latest theories, these extra dimensions describe the strength of the fundamental forces, among other things.
If these extra dimensions have changed their size since the Big Bang (in a similar way to the expansion of our own 3D-space but at a much smaller rate), then we may expect that nature's forces have also changed in strength.
A new development of such ideas comes from Stephen Hawking and his colleagues. They are suggesting that dark matter - the gravitationally dominant, unidentified matter that seems to pervade the universe - is a consequence of "force-leakage" from extra dimensions into our own 3D universe.
These concepts are not the only ones being advertised by imaginative theoreticians.
Another popular idea receiving attention is much simpler - let the speed of light, c, vary with time. However, one of the fundamental postulates of Einstein's 1905 Special Relativity Theory is that c is as solid as a rock. It is constant and does not vary even for rapidly receding observers viewing a stationary light beam. Remove this principle, and Special Relativity (from which the famous and ultimately catastrophic E = mc2 was obtained) crumples. And Einstein's General Theory doesn't get us out of trouble here since it, too, is based on the same fundamental postulate. However, if Einstein were around today, he would be urging us to explore such possibilities, in the hope it could help solve mysteries such as dark matter, varying constants such as the speed of light, and recent observations which suggest that the expansion of the universe is accelerating.
Varying-c is appealing, because it can provide an alternative to the theory of "inflation", which holds that the universe underwent a dramatic expansion in its first few moments. This notion has been invoked to explain why the temperature of the cosmic background radiation left over from the Big Bang is virtually identical in all regions of the universe. It permits the now-distant parts of the universe to have once been in causal contact.
Varying-c allows the same thing, provided c was sufficiently large in the past.
So, how can we check such ideas? Nature generously provides us with "time-travelling laboratories" in the form of distant quasars. A quasar is a compact but highly luminous object, powered by a black hole, and is seen at enormous distances from us. They are so luminous that we can make astonishingly precise measurements.
When gas around a distant galaxy happens to intersect the sightline to a more distant quasar, a characteristic absorption fingerprint is superimposed on the light from the quasar. This fingerprint gives a very precise measurement of the energies of different elements in the gas.
The time it has taken to travel from the gas cloud to us may be more than 12 billion years, or about 90 per cent the age of the universe.
These characteristic fingerprints can then be compared with the same ones made today in the laboratory. The specific physical quantity that we can scrutinise in this way is something called the "fine-structure constant", which is given the Greek symbol alpha.
The value of alpha depends on the value of three other constants: the charge on the electron, e; Planck's constant, h (an important quantity in quantum mechanics), and the speed of light, c.
Alpha quantifies the strength with which electrons are bound to nuclei or, put another way, the energy content of an atom.
My colleagues and I at the University of NSW and other universities around the world have been making such measurements using 75 quasars over the past few years. We have found the curious result that there may be evidence in the data for a change in alpha. It is a very small change, and if it turns out to be correct, it will lead to some radical new ideas in physics, and may offer the first experimental support for some of the theoretical ideas outlined earlier.
Assuming that the quasar observations are correct, new ideas are emerging as to which of e, c or h has or have changed. According to recent ideas from Paul Davies, Tamara Davis and Charley Lineweaver, there are new reasons to suspect c is the culprit.
In a letter to the prestigious journal Nature on August 8, they suggest that anything other than varying-c might result in the violation of a well-accepted characteristic of black holes. Black holes are thought to have an "event horizon", a boundary surrounding them from within which light cannot escape, forever isolating their innermost regions from the rest of the world. If, they argue, e changed, then the event horizon could shrink, and perhaps even vanish, exposing the very centre of a black hole.
This would violate a well-known law of physics (the second law of thermodynamics, the one that renders perpetual-motion machines impossible and defines the arrow of time).
It also disagrees with the 1969 "cosmic censorship" idea proposed by the British mathematician Roger Penrose, that nature does not permit us to see a "naked singularity", the point of infinite density at the heart of a black hole.
The great modern optical telescopes - such as the Keck telescope on Hawaii and the European Southern Observatory's "Very Large Telescope" in Chile - are already providing a rapid flow of quasar data. Within the next couple of months, my colleagues and I are due to publish further data from the Keck telescope, more than doubling the previous sample, and supporting our previous experimental results.
But all the data so far comes from the same instrument and telescope, a point of obvious concern. We have thus embarked on the analysis of new data recently obtained using the VLT, and we expect to confirm or refute the Keck experimental results within two or three years.
If it is confirmed, we can be confident of enormous activity among scientists across the world, vigorously attempting to push the great scientific theories to their limits, and beyond.
Dr John Webb, associate professor at the school of physics, University of NSW, is leading the experimental project to check on the constancy of the laws of physics.
So small in fact, that they are physically impossible to detect given the Uncertainty Principle. Very convenient theory.
"We think there are more dimensions than three."
"Prove it."
"They're so small that they're impossible to detect."
"Riiigggghhhhtttt."
"Assuming that the quasar observations are correct" is a candid statement starkly missing from his totally self-absorbed dogmatic brethren.
A refreshing departure.
If you can vary C, then isn't it possible that 6,000 years at our relative C could be billions at a higher C ?
Hmmm. Like I said, dangerous ground the Godless are treading.
The speed of light --- or anything else --- cannot slow down. One more recent torture of the language, much like "cheaper prices" and "warmer temperatures."
On the other hand, why would one expect newspaper writers to be able to speak and write in their native tongue? They are those who failed to be admitted into any other graduate school.
then aging would have occured (relative to what we know it as today) at a rate proportional to the speed differential between then and now. How would biological processes know that the speed of light changes? Also, one cannot say such things without saying who the observer of such processes is.
I thought most folks went along with the electro-weak theory that unified electromagnetism, the weak force and the strong force back in the 70's. Have I gone senile or am I just being pedantic?
Length, width, heighth, and depth. Seriously, though, what are the three dimensions? Roll, pitch, and yaw? Zoom, pan, and skew?
…the Big Bang created our universe…
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