Precision Science August 25, 2008Posted by gordonwatts in physics.
You can tell how old a set of tools for a field is by how precise their measurements are. Take the top quark. Its been around since 1996. The latest top quark mass result from both CDF and D0 is 172 +- 1.22 GeV – so we know that to better than 1%.
Some of the most stunning recent discoveries in science have been dark energy and dark matter. Well, I guess I shouldn’t call them discoveries — we don’t know what they are yet — but the fact that something is there is definitely a discovery. But the thing about astrophysics is that it isn’t a precision field.
The news was not in Dr. Riess’s value… , but in the precision with which his group claimed to have measured it: an uncertainty of only 4.3 percent.
Only 30 years ago, distinguished astronomers could not agree within a factor of two on the value of Hubble’s constant, leaving every other parameter in cosmology uncertain by at least the same factor and provoking snickers from other fields of science.
Actually, even more recent than that! I remember a rather famous string theorist standing up and claiming “Hey – in cosmology we have finally learned how to use error bars!” And then poking fun at the size of the errors in astro physics.
But that is always the way when you find something new. The top quark, when we discovered it, we basically knew it was there and kind-a knew its mass. We have then spent the last 15 years making the measurement steadily more precise (knowing that mass very well tells us a lot about where to find the Higgs).
Getting down to the 1% level, or the 5% level, even, is a lot of careful work. And, at some level, not as much fun as actually being the first to measure the value. But after verifying that the discover exists, it is the most important thing. That is the beauty of science: all the numbers are connected. The more you know one set of numbers, the better you can predict a second.
Getting the top quark precision down has been 15 years of hard hard work, many graduate student theses, and many post-doc years. But because of that we know a lot more about where to hunt for the Higgs. Doing the same in astrophysics is bound to help with the quest to understand dark energy and dark matter. Can’t wait!
P.S. Can you tell I wrote this on vacation? I’m reading the newspaper!!