Archive for the ‘Astronomy’ Category

There is a word for everything that exists, for the sum total of all the atoms, mice, cities, forests, planets, galaxies, and galactic superclusters that exist, have ever existed, or will ever exist. That word is “universe”. It used to be “world”, but then the totality of everything got too big for the world and a new word was needed. It’s possible that a new word is needed again.

The word, if it is indeed needed, is “multiverse”. [1] It sounds like it means multiple totalities of everything, which wouldn’t make any sense. It doesn’t quite mean that; like world before it, the concept of a universe has become too small to contain everything. The world is what contains everything that we encounter, and — for almost all of us — our lives, beginning to end. It is also a ball of rock hurtling through empty space as it orbits the sun. There are other balls of rock hurtling through empty space orbiting the sun. There are even more balls of rock hurtling through space orbiting other suns. A world still contains us, but is too small to contain everything.

Our universe is a collection of stuff — mostly Dark Energy with some Dark Matter and a tiny bit of ‘ordinary’ matter thrown in for seasoning. The latter two are organized into web-like networks of galactic superclusters. There are also photons (light), neutrinos, black holes, and — very, very, very, very occasionally — a human. (There is some overlap in these categories.) In addition to all being in roughly the same place (give or take a few tens of billions of light-years), all of these things obey the same laws of physics.

So once upon a time, we took our previous concept of world and applied it to all the balls of rock flying through space. We did the same thing with “sun”. It was the ball of fire in the sky, the source of light and energy and life for all things. Our sun still is that, but any ball of gas shining through fusion and with planets orbiting it can now also be a sun.

And just like that we can generalize the word universe as a region, or perhaps bubble, of space governed by a particular version of what we call the laws of physics. In other universes the laws might be slightly different — electric charges might attract and repel each other with a strength that is a bit stronger or a bit weaker; or protons might weigh slightly more or spacetime might bend more easily. Or, the laws might be very different. There might be a completely new force; say something like electromagnetism that only acts on electrons and not protons. Each universe would behave slightly, or drastically, different. Most would collapse a tiny fraction of a second after forming. Some will expand so fast galaxies and stars and planets will never have time to form. A tiny few will have the right conditions to support life.

Now, what’s weird is not that we can imagine such universes, but that there is a reasonable way they could all exist, and exist within the same “totality of everything” that we do, separated not by some mystical dimensional barrier, but simply by ordinary space. Incomprehensibly large tracts of space, but ordinary space none-the-less.

This is the crux of the multiverse theory, which has become quite popular recently. Through a string of apparently disconnected theoretical developments this picture of bubble universes spread throughout a much more vast space has gone from pure fantasy to quite conceivably real. (Note the qualifier in the previous sentence. Many of the pieces required by this theory have not been empirically verified.)

[1] I’d nominate “cosmos” in memory of Carl Sagan, but multiverse seems to have won for now.

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I know you were all on the edge of your seat to find out the winner of Survivor: Universe. It was a long, drawn-out drama-fest, but in the end it was everyone’s favorite galaxy group Arp 274! I shudder to think about the riot that would have accompanied an NGC 4289 upset.

The NASA site has the larger image and a video about how it was made.

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Survivor: Universe

This is very cool, the Space Telescope Science Institute, the people who decide what research is done with the Hubble Space Telescope, are holding a public vote on which object to image.

Now that I think about it, they should have called it “Survivor: Universe” and let people vote against objects, ’cause being mean-spirited is way more fun. I mean, look at NGC 4289. It totally snubbed ARP 274. Don’t you see the way that it’s standing!??! It’s all “talk to the spiral arm, ’cause the central bar ain’t listening.” And for what? It thinks ARP 274 got more dark matter? Not good enough, vote that bastard off already.

Ahem. Meanwhile, Seth at the US LHC blogs wonders if the LHC experiments can do something similar. I kinda hope they don’t. Do we really need national TV exposure of all the ways the different quarks hate each other? That shit is ugly.

Anyway, go vote: there are prizes!

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The Boston Globe runs a beautiful feature called “The Big Picture”. The most recent features images of The Sun which are breathtaking.

One thing I find particularly cool is that many of the most detailed pictures were taken with ground based telescopes, such as the Swedish 1-m Solar Telescope. They use the full set of tricks to get this amazing resolution — including adaptive optics, where the telescope’s own mirror is deformed to match the distortions in the Earth’s atmosphere.

The picture above is dramatically reduced in size and quality; go see the real thing.

In other amazing-space-image related news, NASA will try to fix the Hubble Space Telescope tomorrow by switching to a backup system. The Hubble has been unable to send pictures back down to Earth for a few weeks now, as it’s come down with a bad case of broken electronics. In the meantime, they’ve still been able to do useful science by obtaining ever-more accurate positions of stars.

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Very broadly speaking, the universe is made of three things. About 22% of it holds stuff together. This is called dark matter. Another 74% of it is pushing everything apart; this is dark energy. The last 4% is “everything else” and attends to inconsequential details like galaxies, stars, life, light, and Brad Pitt. While a fair amount is known about the last 4%, due to the successful research program known as “almost all science ever done”, very little is known about the first two.

Now, in a stunning breakthrough, we find the theory that dark matter is made of ghosts. Aside from a couple flaws*, the idea makes sense. After all, dark matter got it’s name because you can’t see it, and you can’t see ghosts either.

However, it seems to me much more likely that dark energy is made of ghosts, since dark energy provides a repulsive force and ghosts are scary.

*Specifically, the main flaw is that it’s completely nuts. Pamela gave a nice run-down of why in her post in case you actually needed convincing.

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