Doug's Darkworld

War, Science, and Philosophy in a Fractured World.

Dark Matter Revisited, Real or Memorex?

with 4 comments

fritz_zwicky.jpg
Fritz Zwicky, unsung genius.

As a break from the ongoing blood and puppet shows in the Middle East, dark matter! What the heck is dark matter? Nobody knows. See, this was an easy blog. Well, it’s not quite that simple. Dark matter is a scientific mystery, and both an example and a warning about inferring the existence of the unknown from the known.

First, dark matter. (There is also dark energy, but I don’t even want to go there.) Scientists infer that something called dark matter exists, even though they can’t detect it directly. Scientists theorize that dark matter exists because of puzzling discrepancies in what they observe of the universe. They are literally seeing the unseen by the effect it has on the visible universe. More on this below.

A good example of how the unseen is inferred from the seen is the historical discovery of the outer planets. After Newton’s discoveries about gravity and physics, astronomers were able to precisely predict the path of the planets through the sky. Problems eventually arose, there were irregularities in the orbits of the outer planets, Jupiter and Saturn. Uranus, Neptune, and Pluto cannot be seen with the naked eye and were not discovered until the scientific era. (Not quite true, under optimal conditions Uranus is visible to a person with good vision, but it’s so faint and rarely visible that it’s no wonder the ancients didn’t notice it.) By studying the irregularities in the orbits of Saturn and Jupiter, scientists predicted there were other planets. Using their knowledge of physics, they predicted and then discovered Uranus, Neptune, and Pluto.

In the very same fashion, looking at the universe at large, scientists see irregularities that defy the laws of physics. The galaxies for example don’t have enough visible mass to stop from flying apart as they spin, among other irregularities. Scientists conclude that some sort of invisible matter must exist to account for these discrepancies. And thus dark matter was born. Long story short, maybe dark matter is some sort of ordinary matter that is hidden somehow, burned out suns, non reflective gas, who knows. The other possibility is that dark matter is some sort of invisible subatomic particle or particles that are invisible but still exert gravitational attraction.

All current theory and observation is that dark matter is the later, it’s sort of the invisible lattice or framework that the rest of the universe is built upon. Science has even mapped out the distribution of dark matter, and there have been exciting discoveries recently. Um, exciting if a person gets excited about physical cosmology. And that in a nutshell, is that. Dark matter is a blank spot in our understanding of the universe, Terra Incognito if you will, but it will be discovered eventually.

Except of course, maybe dark matter doesn’t exist at all. Going back to our planets example, there were irregularities in the orbit of Mercury that also couldn’t be explained. Astronomers spent a lot of time and effort looking for the hypothetical planet they named Vulcan, that just had to be orbiting somewhere near the Sun and Mercury. There was and is no planet Vulcan, it turned out science didn’t know as much about physics as they thought they did. A fellow named Einstein came along and upset the applecart with his theory of relativity. When relativity was plugged into the equation, the irregularities in Mercury’s orbit were very neatly explained. So neatly in fact that it is considered one of the proofs that Einstein’s crazy sounding theory is actually correct.

So I have no opinion on dark matter, to even talk about physical cosmology one has to know math that would make an amputation seem pleasant in comparison. I like the idea of an invisible matrix holding the universe together, that certainly doesn’t contract any spiritual beliefs I am aware of. Maybe even the opposite. There’s also hints that there may be something beyond Einstein, the so called Pioneer Anomaly has made scientists scratch their heads for a few decades now. For some as yet unknown reason these two early space probes are moving slower than by all rights they should be. Some invisible force appears to be holding them back slightly. Maybe some future or current genius will come up with a theory that explains the observed problems in cosmology without invoking invisible mass. I’m glad scientists are working on the problem, and I will report new developments in this field as I become aware of them.

Speaking of awareness, it has been brought to my attention that one of the people who originated the concept of dark matter did not get the credit he deserves. Fritz Zwicky, a brilliant astrophysicist, has been neglected in the history books. He was a brilliant scientist who contributed a great deal to our understanding of the cosmos, and by all accounts a fine human being. Rest in peace Fritz, you and your contributions shall not be forgotten.

(The above image is claimed as Fair Use under US copyright law. It is not being used for profit, it is central to illustrating the post, and it is an historically important image.)

Written by unitedcats

February 12, 2007 at 10:54 am

4 Responses

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  1. Interesting piece Doug :). I talked a bit about dark matter on View for the Edge when “it was imaged” recently.

    http://blog.globalparadigm.info/2006/08/21/chandra-dark-matter-discovered/

    The fascinating thing about that experiment is that it shows conclusively that there is a concentration of gravitational mass existing apart from the concentration of physical matter in that region of space. To me, that means that SOMETHING is responsible for that gravitational anomaly, something that scientists call “dark matter” but it doesn’t do much to explain or describe what it is.

    And thats where I think your analogy with Mercury and Vulcan falls down. When the orbital data of Mercury was initially explained, scientists of the day used a very specific phenomena to try and explain it. That phenomena, the existence of another planet, proved wrong, but the orbital data STILL needed explanation.

    Dark matter is different from this in significant ways. “Dark matter” is a catch all term for the basic “fact” (pretty much demonstrated by the recent experiments you described) that there is more gravity out there than we can account for by what we see. Calling it dark matter is just a way to reference something we know little about really … its not a specific explanation in the way Vulcan was for the orbital perturbations of Mercury.

    I find this a fascinating area of physics myself (course I’m geeky that way, lol) … one of the reasons, IMO, that Einstein had such difficulty with gravity is that whole question of dark matter. How was he expected to formulate an accurate theory of gravity when he understood only a fraction of the gravity-generating “stuff” in the universe, matter? We need to explore dark matter more, and we need to start finding out about what it is, but I have to take issue with your statement that it doesn’t exist … the University of Arizona data shows that there is clearly SOMETHING there causing a gravitational effect, outside anything we would term matter. If you don’t like “dark matter” we can find a new term, but SOMETHING causes those gravitational effects.

    elronsteele

    February 12, 2007 at 1:59 pm

  2. very interesting article! I’m fascinated by stuff like… I don’t understand half of it, but I’m still fascinated by it! :P

    just wanted to drop by and say hi. My work has attempted to block blogs… I made the case that I get most of my legitimate news from your blog… but alas, I can only view, not comment… :(

    so, not to get all Big Brother on you, but even if I don’t comment… I’m watching you….

    *cue twilight zone theme song*

    KrispyDixie

    February 13, 2007 at 8:25 am

  3. Hi Doug,

    Another fascinating article on dark matter:

    http://news.independent.co.uk/world/science_technology/article2134891.ece

    -Jack

    bereans

    February 13, 2007 at 9:33 am

  4. Cool article, keep posting on dark matter! It’s very interesting, and your writing style is great, very smooth to read.

    Fritz Zwicky did get some recognition, I named my band after him a few years ago, there is also a lunar crater and asteroid named after him. Anyone who knows a moderate amount about the cosmos should know who he is, or at least have heard of!

    David

    September 23, 2009 at 1:40 pm


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