Tuesday, August 22, 2006

Proof of Dark Matter?

See the article: Scientists Offer Proof of 'Dark Matter'
For decades, many scientists have theorized that the universe is made up of nearly undetectable mysterious substances called dark matter and dark energy. But until yesterday there was no proof that the subatomic matter actually exists.

After studying data from a long-ago collision of two giant clusters of galaxies, researchers now say they are certain dark matter does exist and plays a central role in creating and defining gravity throughout the universe.

While the scientists are still not sure exactly what dark matter is, since they have yet to identify it in a laboratory, they said that the workings of the universe cannot be explained without it.

The finding will have potentially great impact on an active debate among physicists and cosmologists about not only dark matter but also the workings of gravity that it helps explain. Indeed, the theory of dark matter evolved largely to explain the finding several decades ago that there was not enough visible matter in the universe to produce and account for the gravity needed to keep galaxies from flying apart. [emphasis added]
Not enough matter in the universe to keep the galaxies from flying apart? What on earth (figuratively speaking) does this mean?

Enlightenment scientists proposed that the universe is eternal, without beginning or end. This of course is in direct contradiction with the Western religions that teach that universe was created by God and will end someday, and indeed, that was most likely specifically why the "eternal universe" hypothesis was created in the first place. It is however, an old theory, going back to some of the atheistic and materialistic Greeks philosophers who lived before the time of Socrates.

Now of course, the question of whether the eternal universe (or steady-state) hypothesis is true or not is claimed to be a matter of science, and if it seems to be highly probable, then that may force the religious to rethink their faith.

Einstein is usually famous for his special theory of relativity, E = mc2 and all that, but his most significant theory is that of general relativity, which explains how gravity works. Now general relativity is a heavy-duty and difficult-to-understand theory, but is one which mathematicians call 'elegant' in its basic simplicity.

But this elegant theory didn't give Einstein the results that he wanted: it showed that the universe could not be static and eternal, but instead must either contract or expand, having a beginning, or end, or both. This was unacceptable, so he added a "fudge factor" (the so-called cosmological constant) to his equations, ruining their elegance, but it makes the equations do what he wanted: make the universe static.

Belgian physicist and Catholic priest Msgr. Georges-Henri Lemaître called Einstein on this fudge, and instead proposed the 'primeval atom' theory, which implied that the universe was created at some time in the past; Msgr. Lemaître's enemies coined the term 'big bang' in derision of his theory, but later evidence gave further credence to the creation event. Einstein later approved of this theory (and also had a lifelong fascination with the doctrine of transubstantiation).

By the 1960s, the 'Big Bang' theory went unchallenged. The data implied that the universe began at some point in the past, and will expand forever until the entropic "heat death" of the universe will make it eternally changeless. But some scientists did not like this implication of a Creation. They theorized that if the amount of matter in the universe were large enough, then the big bang would eventually contract again, into a "big crunch", and with some hypothetical hand-waving theories, would be able to expand again. The universe would then be eternal; if not static, then at least it would eternally fluctuate, and they would not be bothered with the notion of a Creation, or most upsetting to them, a Creator.

But there isn't enough matter in the universe to allow it to eternally fluctuate. All the stuff that can be seen, or can reasonably be expected to exist, falls short of the required amount. Some physicists brought back Einstein's cosmological constant fudge factor to make this eternal fluctuation possible, but that is just inelegant and arbitrary. It shows that they are desperate. More clever physicists proposed instead "dark matter" and "dark energy". It can't be seen in the universe, and has never been seen in the laboratory, but they SO BADLY want to have an uncreated universe, that dark matter JUST HAS TO EXIST. They want, Want, WANT it to exist, and so are scrambling to find it. There is no theoretical necessity whatsoever for it, nor is there any theory that describes what dark matter may be: it is an ideological theory, period.

So they claim to have found this dark matter, and it will be a part of science textbooks, PBS science documentaries, and New York Times editorials for years to come. But not all believe the findings:
Stacy McGaugh, an astrophysicist at the University of Maryland, has been one of the dark-matter skeptics, and he said yesterday that he remained unconvinced.

"I've been aware of this result some time, and I agree that it is interesting and may make more sense in terms of dark matter than alternative gravity," he said. "However, it is premature to say so."

He said that a definitive detection of dark-matter particles would mean "grabbing them in the laboratory, not just inferring that their effects can be the only possible explanation for an observation before the alternatives have actually been checked."

2 comments:

  1. The presence of dark matter has less to do with avoiding a creation event and more to do with explaining our observations. We can see the rotation of galaxies and the motions of bodies in the heavens, and at a smaller scale, relativity gives us excellent predictions about how gravity pulls these things around.

    Unfortunately, at larger scales, these predictions break down a little bit. If we add up all of the mass in a nearby spinning galaxy, we find that there is insufficient gravity to hold the galaxy together. At the rate it's spinning, it should be flying apart. "Something else" must be exerting gravitational influence to hold everything together.

    So, when things don't make sense, what do we do? We check our assumptions. Primarily, the assumption that we can *see* all of the mass in that galaxy. That's all dark matter is: the prediction that there's stuff out there that we can't easily see. And it makes perfect sense. Just because a building casts a shadow at dusk doesn't mean things in the shadow don't exist.

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  2. David,

    Thanks for the correction. My 1986 Caltech physics degree has gotten very rusty. Back in those days the central concern was of the total mass in the universe.

    I left the field when I started questioning some of the basic assumptions of physics: my faculty advisor and friends told me to drop that line of research or else I would never get a job in academia. But it was these lines of investigation into basic causes that were the most fascinating part of physics for me. Just study the history of the development of physical theory.

    I came up with a Gedankenexperiment that showed a logical contradiction between quantum physics and relativity. Tweaking relativity a bit would fix the problem, but no one wanted to hear about that.

    Why bother, I thought, and instead got a good paying job in industry instead!

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