It's DARK Out There! First direct evidence of Dark Matter?

Science has, as yet, only been able to detect about 5% of the total make up of the universe. We have lots of hints and mathematical calculations telling us about the rest of it, but it is elusive stuff. Of the 95% of the universe as yet unseen by humans, it breaks down into two classes: Dark Matter (25% of the universe) and Dark Energy (70% of the universe). These two things are needed to explain how the universe is expanding, why it hasn't expanded faster, and why certain astronomical objects behave the way that they do. It can be summed up this way: what we can see in the universe just isn't enough stuff to hold everything together. Galaxies behave as if they have a lot more stuff in them. Using how they behave as a guide, physicists can mathematically guess at what the Dark Stuff should be like. Without this hypothetical Dark Matter, galaxies would behave differently and, in fact, the entire universe would have blown apart much faster in the Big Bang and you and I would not be here to debate Bush's latest Big Flops.

Things got even more complicated when it was discovered that the speed at which galaxies are speeding away from each other is ACCELERATING. Something is actually PUSHING them apart. This was completely unexpected. The only way to explain this was to hypothesize that 70% of what we see is Dark Energy, undetectable to us in most ways, which acts in opposition to gravity on large scales.

Until recently both Dark Matter and Dark Energy could only be indirectly detected, by seeing how the universe deviates from what is expected from regular matter and energy and figuring out what mathematically fits the bill.

According to BBC News, we now have a much more direct detection of Dark Matter. It goes like this. When galaxy clusters collide, the results are pretty impressive. Want to feel tiny? Listen to this:

"The kinetic energy of this collision is...enough to completely evaporate and pulverise planet Earth ten trillion trillion times over," said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, US.

When two galaxy clusters crash like this, the gasses within the galaxy cluster and the galaxies themselves get smashed apart. The gasses essentially interact, slowing down, while the galaxies speed on at a faster rate largely unhindered by the gasses. Most of the mass of a galaxy cluster is gas, so if only normal matter existed, most of the mass of the colliding galaxies would slow down and only a small part would speed off with the galaxies.

Astronomers have now observed one of these huge collisions and found that the vast majority of the mass of the galaxy clusters speeds on with the galaxies, with only a small part slowing down. Hence there is a great deal of mass in a galaxy that has as yet only been hypothesized to make the mathematics of the universe work. Hypothesis is now supported by observation.

This of course still means that 70% of the universe remains to be directly detected, but all in good time.

As a bit of political spin, I should note that part of the data used to detect the Dark Matter came from the Hubble telescope, which Bush wants to abandon to "save money." This is one more example of Bush having no idea either what is important to science, or what it means to save money. Hubble is one of the most valuable pieces of scientific equipment we have.

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