Posts Tagged ‘astrophysics’

Celestia

Posted: 1 December 2007 in Uncategorized
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When I was around 12 or 13, I first got a hold of my stepfather’s physics text book. It was magic. The rules that governed the physical world were right there in the form of equations on a page. I was totally captivated. Newton’s laws of motion, gravity, angular momentum, and the theory of relativity. When I first learned about relativistic time dilation, it was life-changing. I resolved to become an astrophysicist. A lot of changes happened in my life that turned that dream into my current one. But, like all first loves, it never went away.

When I got my first computer, I had hopes of writing a program that would plot the positions of the stars as they were in space (3-D) versus how they appeared in the Earth’s sky (2-D). I achieved a little bit of success getting the vectors worked out from the distance, right ascension, declination and so on. I had no easy way of visualizing it though. Doing 3-D plots in BASIC back in 1990 wasn’t the easiest thing in the world. So that project died.

Then like a ghost, Celestia came to me last night. Wrapped up in her open source glory, I dared not even dream that she could perform what I had so long abandoned all hope of. But she did my friend, she did. (My wife won’t like this imagery :))

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Wherefore art thou Dark Matter?

Posted: 29 October 2007 in Uncategorized
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Astronomers have theorized for years that there must be more mass out there than we can see. Based on the movements of galaxies, star systems, and gas clouds the number of stars just can’t account for it all. Enter dark matter. Matter we can’t see. Special stuff. Even a whole Dark Galaxy.

On a side note, I’ve always thought that would make the perfect penal colony for an intergalactic empire.

“Mr. Adams, for your crimes against the Blagoblag, you are hereby sentenced to spend the rest of your natural life exiled to … the Dark Galaxy.”

“Noooooooooo!! Please, execute me instead!”

So a couple of Canadian astronomers (why their Canadaness is important, I don’t know) have proposed a new theory of gravity that dispenses with the need for dark matter altogether. From a strictly lay viewpoint, since I don’t have enough of a physics background to make an informed assessment, dark matter has always struck me as ad hoc. So dispensing with it would be much more elegant, in my opinion. Of course it would mean the end of the Dark Galaxy and my dreams of a vast network of prisons for political dissidents from the Rebel Alliance.

Last summer, observation of a galactic collision in the Bullet Cluster was touted as an event that caused dark matter to separate from the regular matter in galaxies and was considered evidence of dark matter’s existence. Enter Canadian astronomers: claims of dark matter’s existence premature. They have proposed a modified theory of gravity (MOG), which would account for everything observed in the collision. Excellent. Note: they are not announcing the theory, which has been around for a year or so, but the application of the theory to actual observed data.

John Moffat, the lead researcher, makes a great point that mirrors my feelings about dark matter quite well. He compares theories of dark matter to the 19th Century theory of the luminiferous aether, the hypothetical medium of space through which light was able to travel. “They saw a glimpse of special relativity, but they weren’t willing to give up the ether. Then Einstein came along and said we don’t need the ether. The rest was history.” [source]