WEBVTT 00:00.000 --> 00:12.720 Can you inform us about the four fundamental forces of the universe and the balance between 00:12.720 --> 00:13.720 them? 00:13.720 --> 00:17.880 Who possesses the faculty and knowledge that gives rise to these forces? 00:17.880 --> 00:25.100 Yeah, so the four fundamental forces has been really, I would say, a story of progress 00:25.100 --> 00:27.700 of unifying different things together. 00:27.700 --> 00:34.100 So we typically talk about gravity as one of these forces, about the electromagnetic, 00:34.100 --> 00:39.400 which is magnetism and electricity, and then two nuclear forces, the weak and the strong 00:39.400 --> 00:41.300 force. 00:41.300 --> 00:44.140 And so actually, that's been a story of unification. 00:44.140 --> 00:49.520 So it used to be that magnetic and electric forces used to be viewed as completely separate. 00:49.520 --> 00:54.420 And then with Maxwell's equations in the 1800s, those two were unified into one, which was 00:54.420 --> 00:58.080 what we call the electromagnetic force. 00:58.080 --> 01:02.880 Then later on in the 20th century, the weak nuclear force was unified in with the electromagnetic 01:02.880 --> 01:03.940 force. 01:03.940 --> 01:06.140 And so people would talk about the electroweak force. 01:06.140 --> 01:08.920 And so then we were down to three. 01:08.920 --> 01:14.640 And then now with the standard model, which we talked about before, the strong force and 01:14.640 --> 01:18.300 the electromagnetic and the weak forces are now unified. 01:18.300 --> 01:24.260 So in some ways, you could talk about two forces, the standard model and then the gravity 01:24.260 --> 01:26.880 as being the one which is left out. 01:26.880 --> 01:30.880 And it's not at all clear how to bring gravity into that picture. 01:30.880 --> 01:35.880 But one of the things I would say that has bothered people about the standard model is, 01:35.880 --> 01:43.460 again, this presence of tuning parameters, parameters that are not required by the theory, 01:43.460 --> 01:47.620 but have to be just right to match what the experiments are. 01:47.620 --> 01:51.600 And so this gets back to the aesthetic issues of physics. 01:51.600 --> 01:56.260 So initially, if you think about history going way back, we had five elements, you know, air, 01:56.260 --> 01:59.520 fire, water, and so on, it seemed very simple. 01:59.520 --> 02:03.840 Once people started doing chemistry, they found more and more elements. 02:03.840 --> 02:07.800 And so, you know, there's gold and lead and so on. 02:07.800 --> 02:13.340 And eventually, by the end of the 1800s, we had a hundred or more elements. 02:13.340 --> 02:16.620 And that just seemed too many for people, like why should there be so many elements? 02:16.620 --> 02:21.000 And so they started to seek for a way to unify those things. 02:21.000 --> 02:26.220 And lo and behold, they came up with nuclear theory, which then has looked simple at first, 02:26.220 --> 02:29.900 just protons, electrons, and neutrons, just three types of particles. 02:29.900 --> 02:32.040 And that seemed very nice. 02:32.040 --> 02:36.000 And then they continued to do nuclear physics, and they found, well, actually, 02:36.000 --> 02:41.040 now there are hundreds of types of nuclear particles, not just three, neutrinos, 02:41.040 --> 02:43.720 kaons, pions, and so on. 02:43.720 --> 02:45.280 And once again, it looked ugly. 02:45.280 --> 02:53.960 Like three somehow is appealing, but, you know, 246 seems not aesthetically appealing. 02:53.960 --> 03:02.960 So once again, they found a way to unify these into the standard model and quarks and gluons. 03:02.960 --> 03:07.200 And so, at first, there was a feeling that this would be very simple, that we would just 03:07.200 --> 03:12.960 have three colors of matter and we'd unify everything again. 03:12.960 --> 03:17.960 But once again, now the standard model, now we have something like 17 types of particles, 03:17.960 --> 03:21.960 each with different coupling constants and forces between them. 03:21.960 --> 03:23.960 And for many people, it looks like too many. 03:23.960 --> 03:25.960 It doesn't look pretty. 03:25.960 --> 03:31.960 At every stage along the way, what you see is we have tuning parameters, things that are, seem 03:31.960 --> 03:33.960 to be arbitrary parameters. 03:33.960 --> 03:39.960 And I would say many physicists have the desire to have a parameter-free theory, where 03:39.960 --> 03:44.960 everything is just required to be the way that it is by pure logic. 03:44.960 --> 03:47.960 And what we see experimentally is that seems to be not the case. 03:47.960 --> 03:54.960 That, in fact, there are these tuning parameters that are what we could call design parameters. 03:54.960 --> 04:00.960 And so, in theological terms, you could say what many physicists want to do, and actually, 04:00.960 --> 04:07.960 Einstein said this explicitly, was he said he would like to prove that God could not have 04:07.960 --> 04:09.960 created the universe any other way. 04:09.960 --> 04:15.960 What we see, actually, is that God, as far as we know, could have done things differently, 04:15.960 --> 04:21.960 that all of these parameters are free parameters, and they're design choices that were made in 04:21.960 --> 04:24.960 making the universe the way that it is. 04:24.960 --> 04:31.960 And so, I just think, eventually, no matter how far we go, we will still see that there 04:31.960 --> 04:38.960 are these design parameters that are free choices of God that are not required by any 04:38.960 --> 04:41.960 kind of logical necessity or geometry or things like that. 04:41.960 --> 04:42.960 So, let's see. 04:42.960 --> 04:43.960 Let's see. 04:43.960 --> 04:44.960 Let's see. 04:44.960 --> 04:45.960 Let's see. 04:45.960 --> 04:46.960 Let's see.