00:00 What is dark matter dark matter?
00:02 Should be called
00:05 Invisible matter it's matter that doesn't interact with light or with any other charge particles
00:13 Matter that has nothing to do with light. That's the point
00:16 I'm Paul Sutter in this is Paul explains the show where I
00:21 you know
00:24 Explain how do we know that dark matter exists? Well, we don't see it in Earth or the solar system
00:32 You have to look at big scales before dark matter really starts to reveal itself
00:39 And we saw it first in the 1930s with the motions of galaxies inside of galaxy clusters
00:46 They the galaxies were just moving way too fast. The galaxy cluster should have ripped itself apart billions of years ago
00:53 But there was still
00:55 Existing so something had to be gluing all those galaxies even our own galaxy
01:01 The Milky Way just shouldn't be here then in the 1970s
01:05 We discovered that stars are again
01:09 moving way too fast
01:12 there has to be an extra source of
01:16 Gravity to hold the stars in in this source of gravity can't come from something we see like stars or nebula
01:23 Or anything else that glows
01:26 Otherwise, we would have seen it. We would have accounted for it. There is something inside of galaxies
01:32 There is something inside of galaxy clusters that has mass that has gravity
01:36 But isn't emitting any light
01:39 since the 1970s we've gone even further to
01:44 Solidify our understanding of dark matter that we know it exists from the earliest moments of the universe
01:51 We have the cosmic microwave background. This is leftover light from when the universe was just
01:57 380,000 years old and by studying tiny little variations in that light
02:02 We can get a picture a map of what the universe was like back then and guess what?
02:07 There was a lot of matter back then that didn't interact with light
02:11 So we have all these different pieces of evidence that all fit together and all point to dark matter
02:18 very likely
02:20 Dark matter or invisible matter is streaming through the room you're in right now
02:26 But it doesn't interact with light doesn't interact with charged particles. It doesn't interact with normal matter
02:31 So you just don't see it. You just don't care about it's invisible to you
02:35 But at the very largest scales it affects how things move what we do know for sure
02:41 Is that the dark matter does?
02:44 exist
02:47 [Applause]
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