Just Because You Can't See It...

Hello everybody and welcome back from the weekend. I've got one story up today on the website and it's about the two-week summer workshop called the SLAC Summer Institute, or SSI for short. Student workers have been running around the office for weeks getting everything ready for this massive event.

This year's topic? Dark matter. If you haven't heard, allow me to enlighten you. (ha ha ha I'm so clever!)

When scientists observe the way galaxies move throughout the universe—such as the way they spin—they find that the mechanics are all wrong according to Newton's laws of gravity and Einstein's of relativity. The only way the universe can behave as observed is if there is about 20 times as much matter and energy that we can't see than what we can see.

That's right folks, visible matter accounts for only 4% of the stuff in the universe.

So take the entire solar system, the entire galaxy, and all of the trillions and trillions of stars and other galaxies that we can see through our massive telescopes and multiply it by 20.

That's a lot of invisible stuff.

And out of that invisible stuff, roughly 2/3 of it is a substance known as "dark energy" or "vacuum energy." This stuff is causing the universe to accelerate its expansion. You would think that gravity would be pulling everything back together eventually in, say, a couple of trillion years. But no, this stuff is causing the universe to expand faster and faster and faster…

The remaining third is dark matter. Again, we know its there because its gravity effects that of the matter we can see. But we can't detect it. Nobody knows what its made out of. There are a bunch of experiments that are trying to find out, but that is another topic for another day.

Why?

Well because I said so. And because I have an article coming out for the website in the near future about that exact topic…

So I won't waste a good idea for a future reference to satisfy your curiosity now. If you want to know… go find out! Or stick around and keep reading this blog for a few more days.