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Great Void

February 28, 2012

Some things area really, really interesting and people live their whole lives never even realizing it.

I was reading about ‘dark matter’ the other day, because I was wondering why it caused such heated arguments and name calling among otherwise normal, sharp people.

Back in 2006 they were observing these clusters of galaxies flying towards each other.  The visible matter in the galaxies was almost all free gas and maybe 10% stars and such.  As the clusters collided, they noticed that the gas was being pulled toward the galaxies.

That’s not how gravity works though.  Gravity is an force exerted by everything onto everything else.  You are currently pulling, ever so slightly, on every other object in the universe, and everything in the universe is currently pulling you.  The reason we notice earth’s gravity is because it is so big and so close to us.  We also pull on the earth, but we are so small it is not even really noticeable.

So when galaxy clusters collide, the matter that makes up the free gas should be strong enough to pull the galaxies.  The bigger thing should attract the smaller thing, much more prominently than the smaller thing attracting the bigger thing.  But we saw the opposite happen.

We explained it by reasoning that there was a bunch more matter in the galaxies, to the point that the majority of matter was in the star clusters, it was just matter that we couldn’t see.  Matter that doesn’t absorb or reflect light.  This is what they call ‘dark matter’ and this collision is what convinced most people that it does in fact exist.

Another explanation proposed by quite a few scientists is that gravity just simply works differently at great distances and with great masses.

As a layman I don’t really know which one of these seems more reasonable.  You might say that second one is just a cop-out but I wouldn’t be so sure.  A lot of our theories have stood simply because we lacked the means to observe anything that disproved them, or never noticed that there were certain conditions where they weren’t always true.  Proving a theory wrong usually just proves that it was incomplete.

Like, for example, Newton and Einstein differ greatly in their explanation of physics, but neither one is wrong.  Einstein just clarified some things.  Like, matter and energy are the same thing, they are interchangeable.  Matter isn’t really solid, it is a cloud of probabilities of the positions of the particles that make up the atoms that make up the matter.  Electrons don’t really spin around an atom, they do pretty much whatever they want to do.  All we can say is that an electron is more likely or less likely to be in this or that place at any one time.



All of these are fundamentally different than people thought at one time, with huge implications, but for most of our history they didn’t make a difference to what people could observe or the problems they needed to solve.

But we have different problems now.  If we can avoid war and murder and plague, there may be a time when we outgrow our planet.  Our preferred method of moving around, engines that burn hydrocarbons, depends on a resource that is finite and rapidly running out.  We have weapons that are far too potent to safely possess.  We could kill each other, completely, in a matter of minutes.

These problems require that we spread out.  That we explore the vastness of space.  The survival of our species might depend on it.  But if you bring it up,  scientists, politicians, and educators will bring up the limitations, the reasons we can’t do it.  How did it come to that?

The problems are daunting, but so are the rewards.  We kill each other over tiny amounts of energy and metal and land, when the universe is big enough that every person on earth could have dozens of galaxies to himself, if he so chose (and, y’know, if they’re not already occupied!).  A person could explore for the rest of his life.  And this is the first time our species has ever run out of things to explore.  I know there’s caves and uncharted parts of the ocean and inhospitable mountains and such, but how can that compare to the whole universe?  My mind can’t even comprehend setting foot on Mars, and that’s one of the closest things to us.  If someone told me I could explore Titan tomorrow, but that would be the last day of my life, I would do it, without a second thought.  And that’s just one moon of one planet around one star in one galaxy in one group in one cluster in one filament in one area of the universe!

I’m not saying FTL travel and space colonization will be easy to achieve, or even possible.  But it deserves our energy, our thought, and our resources.


Hmm. This was quite a ramble but it turned out all right.

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