Ming the Mechanic:
Where's the dark matter

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 Where's the dark matter2004-02-15 13:44
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Article in The Economist about the likely possibility that the dark energy and dark matter essential to modern explanations of the universe doesn't really exist as predicted.
IT WAS beautiful, complex and wrong. In 150AD, Ptolemy of Alexandria published his theory of epicycles—the idea that the moon, the sun and the planets moved in circles which were moving in circles which were moving in circles around the Earth. This theory explained the motion of celestial objects to an astonishing degree of precision. It was, however, what computer programmers call a kludge: a dirty, inelegant solution. Some 1,500 years later, Johannes Kepler, a German astronomer, replaced the whole complex edifice with three simple laws.

Some people think modern astronomy is based on a kludge similar to Ptolemy's. At the moment, the received wisdom is that the obvious stuff in the universe—stars, planets, gas clouds and so on—is actually only 4% of its total content. About another quarter is so-called cold, dark matter, which is made of different particles from the familiar sort of matter, and can interact with the latter only via gravity. The remaining 70% is even stranger. It is known as dark energy, and acts to push the universe apart. However, the existence of cold, dark matter and dark energy has to be inferred from their effects on the visible, familiar stuff. If something else is actually causing those effects, the whole theoretical edifice would come crashing down.
New analysis seems to indicate that the numbers don't match up, and that remote clusters of galaxies are more correctly explained if they contain more ordinary matter. Not that I really understand much of this, but it is just a reminder that most of the prevalent scientific theories about the universe are just that - theories. Somebody's best guess about how things work, often including weird and unseen factors to get the numbers to fit.

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15 Feb 2004 @ 13:57 by craiglang : Adding Epicycles
Hi Ming,
I think you are right. We are adding epicycles at the moment.

The interesting thing aobut the Ptolomeic cosmology was that computationally, for about 1500 years, it worked the best of any model then created. IT wasn't until Tycho Brahe's accurate measurements of planet positions that it was realized that the ptolemaic universe was somehow flawed.

Similarly, I think that the big bang theory seems to have most closely explained the data to-date. But now, we realize that something is wrong with the model. And this is when science becomes the most fun.  

25 Aug 2004 @ 07:00 by QMAL @ : More than one big bang
Yes - definatly agree with both of you on this, theory changes quite often in science. Many things we accept for fact for a time, change with just a little more or less data. More complexity to the model may not explain much more. I am quite interested in astronomy and astrophysics. When I was a kid about ten of age I tried or did grasp the the big bang theory and my first thoughts were, that this could not work it dosn't add up. There could not have been just one big bang , everything else we see is going in circles. I imagined a series of bangs and resulting expansion, retractions as matirial regathered in the center of galaxies and got re-ripped into black holes, then the dense chilled matter would recollecting to bang agian. Well not long ago I read about a hubble find, some scientists were studying some galaxies in the reshift zone. This is an area close to the suposed vicinity of the big bang where redshift values are different than the surrounding areas. Apparently if I understood correctly , the galaxies studied exibited signs that they were quite old in nature, but in a very young portion of the universe, and moving in different direction than the surrounding younger galaxies. The scientists were puzzled by this. Seems to me that the simple answer would be that there was more than one big bang and these galaxies were from another big bang that is/was currently further away/ago that we can see. Another universe. While I cant do the math on paper to prove this. It would be consistant with my imagined model when I was younger. I think also that the core of the sun is dense ice cold matter. A black hole may be a product of runaway star formation without nuclear ingnition because of extremely high gravimetric ratios....just a thought.

the redshift survey is at


this is fairly interesting


And this one expains the case for the misplaced galaxy thing I refer to


Other stories in
2009-11-01 16:35: Seven questions that keep physicists up at night
2008-10-14 20:33: Where are the podcars?
2008-07-05 00:08: Self-Organized Criticality
2008-05-16 13:34: The Universe as God
2008-01-11 19:00: Richard Dawkins comes to call
2007-12-02 21:10: An E8 theory of everything
2007-09-27 00:46: Parallel universes are a bit more real
2007-07-05 23:40: What happened before the big bang
2007-06-27 00:58: Naïve realism
2007-05-26 02:26: Mars cave

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