Dr. Brian Keating

But it is true that there could be no dark matter, but then you'd have to replace the effects that we know that dark matter manifests as.

You'd have to find another mechanism to reproduce those effects.

Nobody says that there aren't these properties of...

The following situation in a galaxy like the Milky Way galaxy that we live in, there's sort of this known problem that the stars in the Milky Way galaxy are rotating around the black hole in the center of the galaxy at an extremely high rate.

It's as if you were swinging a ball on a string.

You're swinging a baseball on a string.

around your head it's going so fast you can't account like you couldn't account for it by the muscles of the person swinging it you'd have to find some other maybe there's some wind that just so happens to be making a tornado like a dust devil or whatever right around the person but in other words you'd have to come up with some other explanation besides the most simple explanation or the seemingly obvious explanation that there's dark matter

So in a sense, we know that there's gravity.

We know there's electricity, magnetism, radiation, light.

We know about all these forces of nature.

And we know that, I mean, forms of dark matter don't have to be exotic things that we've never encountered before.

For example, back in the 17th and 18th centuries, it was known that

that the planet Uranus, or as some people like to call it, Uranus.

Yeah, I like to drop that every now and then because NASA likes to get a very close look at Uranus.

So they were observing it, and they observed back 300 years ago that it was moving in a very strange way.

It was moving as if it was being pulled upon by some unknown source of gravitation.

They knew about gravity.

They knew what its orbit should be.

if the only other planets in the solar system were Mercury, Venus, Earth, Mars, Jupiter, and Saturn, and they couldn't account for the motion.

This is, again, very simple observations to do at the time even.