Fired Up About Dark Matter | StarTalk

All right, number two. This next question is from, okay, let's see. This is, uh, this is from David Crosby.

Oh, okay, and in his interview with you, he asked me, he was asking me questions. You tell me, you snap, you clipped the question. I clipped a question, and he was very fired up about it. So let's see what he had to ask.

All right, what the hell? What? What? I totally don't understand what dark energy or dark matter are. Why? You sounded angry with me because I got nobody else. Man, you coming to my office saying, "What the hell? What the hell is going on with this? This is messed up. It's your job to be able to know this stuff, and who else I got to ask?"

Okay, so, uh, Neil, what the hell? Seriously, all right? What is dark matter?

Okay, so, I’m happy to answer that question. We have no idea. Wow! Next question.

We do not know what dark matter is. It’s pro—it's probably misnamed. I know what it is. It's—well, sorry, what it should have been called is dark gravity.

There's gravity in the universe; we have no idea what's causing it. If you say dark matter, that implies it's matter, but we don't even know if it is or is not that. But we do know it is gravity with no known source, so it's dark gravity.

We can see it—gravity; we don't know anything else about it. We can't see it, we can't taste it, we can't touch it; our light doesn't interact with it. It doesn't make spectra; we are clueless.

Same goes for dark energy. Dark energy is a mysterious pressure in the vacuum of space that's pressing against the fabric of the universe, making it accelerate in its expansion against the gravitational wishes of the galaxies it contains.

We are deeply steeped in this ignorance. You combine dark matter and dark energy; it is 96% of all that drives the universe, and all we really have command of is that remaining 4%. All the known laws of physics, chemistry, biology are in those 4%.