Saturday, May 14, 2011

Diary of a WIMPy Particle

This post will also be found in Tehachapi's The Loop Newspaper

The Universe is filled with stuff we cannot see. And humans have been coming to grips with these things and forces since, well, basically since we've been human. 

We see the effects of the wind, but we cannot see the wind itself. So we come up with hypotheses about how winds come about. By using our lungs and mouths we can generate small scale effects that are like wind. We do it when we blow up balloons, or blow out candles. So we can hypothesize that there exist large creatures that cause the winds. Some kind of wind spirit, perhaps.

But when we think further and notice that warm air rises out the chimney. We can develop new theories about how uneven heating of the Earth's surface causes air to rise, reducing the pressure at one location which is filled in by the wind, which is air flowing from a place with higher pressure.

Each of these hypotheses explain the wind, but one has built in ways of testing. The scientific one. The hypothesis of uneven heating. Which can be tested by making predictions and seeing if they are born out by the evidence. 

This is the way science works. People make predictions based on how they think the world works. These conceptions of the world are scientific theories. In science, a theory isn't a guess. It is a conceptual model of the Universe. And theories gain credence by how well the predictions they make hold up to comparison with the actual Universe. Plate tectonics (continental drift, earthquakes, and other large scale geologic processes) is accepted by geologists, because the predictions it made are consistent with the observations made about the world.

Astronomers have looked at numerous galaxies, and added up the mass (think weight, though that's not really what mass is) and found that, for the galaxy to behave like it does, there needs to be bore mass, more matter than they can see. The additional matter we can't detect (except by its invisible actions) is known as dark matter. Dark matter theories are a consequence of these observations.

And there are currently competing theories about “Dark Matter”. Recently one of these theories got a boost towards acceptability. This particular theory suggests that dark matter is made up of WIMPs. The is an acronym for Weakly Interacting Massive Particles. Which just means particles that have mass (weight), that don't interact much with regular matter. 

At the bottom of an old iron mine in Minnesota, a lump of germanium has detected a seasonal change which is consistent with predictions made by the WIMP theory of dark matter. Which confirms results found by a laboratory in Italy. 

But the scientists haven't broken out the beakers to celebrate yet. These are the results of just two labs, and several others, looking for the same effects, haven't seen them. One apparently just down the hall from the Italian lab. 

So will WIMPs turn out to be the answer to the dark matter question? Maybe, maybe not. What will happen, is that scientists will continue to test the theory, looking critically at the predictions it makes and seeing whether or not those predictions can be verified. 

Now poets over the ages have complained about how science was taking the beauty out of the world (see Whitman's “When I heard the learn’d astronomer” or Poe's “Sonnet – To Science”). But this just isn't the case. Understanding how the Universe really works enhances the beauty of nature. For even if dark matter isn't wimpy, the force it exerts is holding entire galaxies together, and we can't even see it, except through theory-colored glasses.

No comments:

Post a Comment