WEBVTT

1
00:00:02.857 --> 00:00:05.958
Bio Beats. Class is in session.

2
00:00:07.143 --> 00:00:10.422
Today we go deeper than the atom. Quarks.

3
00:00:11.429 --> 00:00:14.266
You stopped at the atom: protons, electrons, that's it?

4
00:00:14.286 --> 00:00:17.104
There's a basement under that basement, so let's get in it.

5
00:00:17.143 --> 00:00:19.980
Blow an atom up to the size of a stadium:

6
00:00:20.000 --> 00:00:22.837
the nucleus is a pea and the rest is all vacuum.

7
00:00:22.857 --> 00:00:25.694
Protons and neutrons, crammed in that pea,

8
00:00:25.714 --> 00:00:28.551
but they're not the bottom: each one's built out of three.

9
00:00:28.571 --> 00:00:31.409
Electrons ride solo, no smaller parts found,

10
00:00:31.429 --> 00:00:34.266
but crack a proton open: three quarks bouncing around.

11
00:00:34.286 --> 00:00:37.123
Up, up, down, that's a proton,

12
00:00:37.143 --> 00:00:39.980
up, down, down, that's a neutron,

13
00:00:40.000 --> 00:00:42.837
three in a room and they can't get out,

14
00:00:42.857 --> 00:00:45.694
every atom you touch got 'em, no doubt.

15
00:00:45.714 --> 00:00:48.551
Now check the charges, this is where it gets absurd:

16
00:00:48.571 --> 00:00:51.409
up is plus two-thirds, and down is minus a third.

17
00:00:51.429 --> 00:00:54.212
Two ups and a down add up to plus one:

18
00:00:54.286 --> 00:00:57.123
that's your proton's charge, every proton under the sun.

19
00:00:57.143 --> 00:00:59.980
One up, two downs, and it cancels to zero:

20
00:01:00.000 --> 00:01:02.837
that's the neutron, no charge at all, the quiet hero.

21
00:01:02.857 --> 00:01:05.694
They carry color charge: red, green, blue,

22
00:01:05.714 --> 00:01:08.551
not real paint, just a name for the charge behind the glue.

23
00:01:08.571 --> 00:01:11.089
Gluons hold 'em like a rubber band, see:

24
00:01:11.429 --> 00:01:14.266
the farther you stretch it, the more it costs in energy.

25
00:01:14.286 --> 00:01:16.769
Pump in enough and the band goes snap,

26
00:01:17.143 --> 00:01:19.980
the energy makes new quarks, none escape the trap.

27
00:01:20.000 --> 00:01:22.837
Up, up, down, that's a proton,

28
00:01:22.857 --> 00:01:25.694
up, down, down, that's a neutron,

29
00:01:25.714 --> 00:01:28.551
three in a room and they can't get out,

30
00:01:28.571 --> 00:01:31.409
every atom you touch got 'em, no doubt.

31
00:01:31.429 --> 00:01:34.247
Six flavors in the family, here's the list:

32
00:01:34.286 --> 00:01:37.123
up, down, charm, strange, top, bottom, that's it.

33
00:01:37.143 --> 00:01:39.961
But the stuff you touch? Just the up and the down;

34
00:01:40.000 --> 00:01:42.837
the heavy ones decay in a flash, they don't hang around.

35
00:01:42.857 --> 00:01:45.653
Now put a proton on a scale, and get this:

36
00:01:45.714 --> 00:01:48.551
the three quarks' own mass is just one percent of it.

37
00:01:48.571 --> 00:01:51.409
The rest is energy of quarks and glue in motion,

38
00:01:51.429 --> 00:01:54.266
E equals M C squared, mass made out of commotion.

39
00:01:54.286 --> 00:01:57.123
So most of your weight isn't stuff, it's energy locked tight

40
00:01:57.143 --> 00:01:59.980
in three quarks in a room that'll never see the light.

41
00:02:00.000 --> 00:02:02.837
Up, up, down, that's a proton,

42
00:02:02.857 --> 00:02:05.694
up, down, down, that's a neutron,

43
00:02:05.714 --> 00:02:08.551
three in a room and they can't get out,

44
00:02:08.571 --> 00:02:11.409
every atom you touch got 'em, no doubt.

45
00:02:11.429 --> 00:02:14.266
So the atom had a basement, and now you've been down:

46
00:02:14.286 --> 00:02:17.457
three quarks, one room, and the glue holds 'em down.

47
00:02:18.571 --> 00:02:20.091
Class dismissed.