WEBVTT - What is Energy? 0:00:08.760 --> 0:00:10.480 Or Hey, did you have a good snack before you 0:00:10.520 --> 0:00:13.440 just hit record? I did. I just finished the banana, actually, 0:00:13.640 --> 0:00:16.479 And is that banana enough energy to power you for 0:00:16.520 --> 0:00:19.000 a whole hour? Depends on what I'm doing that hour. 0:00:19.200 --> 0:00:23.880 You know, procrastination doesn't take much energy. Well, it's amazing 0:00:23.920 --> 0:00:27.480 to me that you can turn bananas into physics podcasts. 0:00:28.080 --> 0:00:30.880 That amazes you as a physicist. Isn't all energy conserved? 0:00:31.000 --> 0:00:33.800 Shouldn't be possible from a physics point of view? Yeah, 0:00:33.840 --> 0:00:36.720 it might even be possible to do the opposite, right, 0:00:36.800 --> 0:00:43.239 to turn physics podcasts back into bananas. What wouldn't that 0:00:43.479 --> 0:00:46.479 violate the laws I don't know of physics, because imagine 0:00:46.479 --> 0:00:48.680 all those thousands of people out there with this podcast 0:00:48.920 --> 0:00:52.400 turning this into a banana. There must be some loss, though, 0:00:52.560 --> 0:00:54.280 I think they would end up with a smaller banana 0:00:54.320 --> 0:00:57.880 than the when you started with, or overly ripe banana. 0:00:57.920 --> 0:01:00.920 Maybe that's a good way to describe podcast. Maybe you 0:01:00.960 --> 0:01:03.400 can think of I heart media is basically amplifying your 0:01:03.400 --> 0:01:06.440 original banana. That's bananas, Daniel. At least you're feeding your 0:01:06.480 --> 0:01:24.039 mind as well as your body. I am more handmade 0:01:24.000 --> 0:01:27.000 cartoonists and the creator of PhD comics. Hi, I'm Daniel. 0:01:27.040 --> 0:01:30.479 I'm a particle of physicist and a professor at UC Irvine, 0:01:30.840 --> 0:01:35.320 and I am sending you all physics energy, physics vise 0:01:36.240 --> 0:01:39.559 or knowledge is knowledge energy? Daniel, there's a question about 0:01:39.560 --> 0:01:43.600 whether information has mass. So if it does, the information 0:01:43.640 --> 0:01:46.560 would have energy and knowledge is information, So in some 0:01:46.640 --> 0:01:49.480 weird theories of the universe, maybe it does. Wait what 0:01:49.760 --> 0:01:53.840 information might have mass? So all those people listening to this, 0:01:54.080 --> 0:01:57.640 we're increasing their mass only if we actually put some 0:01:57.720 --> 0:02:02.200 information into this podcast. So far, it's just banana jokes, 0:02:02.880 --> 0:02:06.240 basic cholesterol. You know, there's good information and there's bad information. 0:02:06.480 --> 0:02:10.839 Which one is healthier for you? Scientists are still debating it. Yeah, 0:02:11.080 --> 0:02:14.240 stay tuned as they gather more information to answer this question. 0:02:14.520 --> 0:02:17.040 But anyways, welcome to our podcast, Daniel and Jorge Explain 0:02:17.120 --> 0:02:19.680 the Universe, a production of I Heart Radio in which 0:02:19.760 --> 0:02:23.320 we try to sift through all the information humanity has 0:02:23.360 --> 0:02:27.240 gathered about the crazy universe that's out there. We try 0:02:27.320 --> 0:02:30.840 to systematize, we tried to organize, We tried to educate 0:02:30.880 --> 0:02:33.000 you on what we do know and what we don't 0:02:33.040 --> 0:02:37.080 know about this crazy universe, how it works, how things 0:02:37.160 --> 0:02:40.240 slosh and flow around, how it comes together to make 0:02:40.280 --> 0:02:44.320 this incredible, beautiful and dangerous universe that we all love. Wait, 0:02:44.320 --> 0:02:46.280 are you saying that our job here is to take 0:02:46.520 --> 0:02:49.560 everything that's beautiful in the universe, chew it up, eat it, 0:02:49.639 --> 0:02:54.239 and then regurgitated back to people as information edible information. 0:02:54.400 --> 0:02:56.480 I'm not sure which side it comes out, but yeah, 0:02:56.600 --> 0:03:02.320 we consume it and then produce it. It's not a 0:03:02.320 --> 0:03:04.120 pretty picture either way, is it. I like to think 0:03:04.160 --> 0:03:06.720 of it as all part of the information food web. 0:03:07.080 --> 0:03:09.200 You know, don't think so much about who is eating 0:03:09.240 --> 0:03:12.520 who as much as you know information is flowing from 0:03:12.600 --> 0:03:19.560 person to purses. We're all just stardust and predigested information. Yeah, 0:03:19.560 --> 0:03:22.520 although maybe you are the information super predator. You're the 0:03:22.560 --> 0:03:28.320 apex information consumer. Oh I really huh? And nobody has 0:03:28.360 --> 0:03:30.480 ever called me the apex anything. Well, think about it. 0:03:30.520 --> 0:03:32.799 You talked to lots of scientists, and you distill from 0:03:32.880 --> 0:03:36.360 all of them little bits of crucial science knowledge. Wow, 0:03:36.640 --> 0:03:38.680 maybe that's why I'm so full all the time. It's 0:03:38.680 --> 0:03:41.320 a lot of bananas to keep that. Or you're just 0:03:41.360 --> 0:03:44.880 consuming all those scientists brains effectively. That makes you so 0:03:45.120 --> 0:03:48.000 like a science zombie. I'm not sure now, zombie too. 0:03:48.080 --> 0:03:51.560 Oh my goodness. First I was regurgitating. Now I'm stumbling 0:03:51.560 --> 0:03:56.600 around half dead. Actually that that is pretty accurate these days, 0:03:57.280 --> 0:03:59.080 at this time in the morning. You do a good 0:03:59.160 --> 0:04:01.800 zombie impression. Now you told me zombies don't always stumble 0:04:01.800 --> 0:04:04.880 is sometimes zombies are fast moving and even articulate. Yeah, yeah, 0:04:04.920 --> 0:04:08.840 it's kind of zombies. Yeah, then the new kinds of 0:04:08.920 --> 0:04:11.160 zombies are now fast and furious. We've got a lot 0:04:11.160 --> 0:04:13.800 of response from the Zombie Star episode, people writing in 0:04:13.880 --> 0:04:17.240 recommending zombie movies that they thought I might enjoy. Oh good, 0:04:17.320 --> 0:04:20.480 are you gonna watching? Do you need an honest answer 0:04:20.480 --> 0:04:24.599 to that question? Why? Well, why not? There's too many 0:04:24.640 --> 0:04:27.000 things out there to watch. So they're on my list, 0:04:27.080 --> 0:04:29.479 but I might not make it. I see, that's the 0:04:29.520 --> 0:04:32.720 political answer, got it, got it. But thank you everyone 0:04:32.800 --> 0:04:35.280 for your suggestions. I will get to them eventually. Well 0:04:35.320 --> 0:04:37.960 I'm curiously know what's on that list. But today we're 0:04:38.000 --> 0:04:40.520 talking about something a little bit different than Zombie Stars. 0:04:40.720 --> 0:04:43.880 That's right. We are venturing into the border between physics 0:04:43.920 --> 0:04:46.960 and philosophy. We are not just trying to understand how 0:04:47.000 --> 0:04:49.839 the universe work, We're trying to understand what it means, 0:04:49.960 --> 0:04:52.000 because physics is more than just a list of laws. 0:04:52.040 --> 0:04:55.800 It's an attempt to get some deep intuitive understanding into 0:04:55.880 --> 0:04:59.320 how the universe works, to reach those ah ha moments 0:04:59.400 --> 0:05:02.920 where you feel I get it. I understand something now 0:05:02.960 --> 0:05:05.200 about how the universe is doing it that I didn't 0:05:05.279 --> 0:05:08.480 understand before. Wait. Wait, wait, wait, we're going into philosophical 0:05:08.720 --> 0:05:12.640 territory here. Can we go back to the zombies? Well, 0:05:12.640 --> 0:05:15.200 we can talk about philosophical zombies if you like. That's 0:05:15.240 --> 0:05:19.040 one of my favorite topics, or the philosophy of zombies. 0:05:19.400 --> 0:05:23.000 M like, is a zombie still a person or not? No, 0:05:23.120 --> 0:05:26.200 that's philosophy by zombies. You know, they have whole journals 0:05:26.600 --> 0:05:30.360 that only zombies, right for Oh no, it is kind 0:05:30.360 --> 0:05:32.719 of a half that discipline. Anyways, you know, the the 0:05:32.800 --> 0:05:36.359 overlap between physics and philosophy is very healthy, very vibrant, 0:05:36.440 --> 0:05:39.600 really fascinating, and for me, one of the motivating aspects 0:05:39.600 --> 0:05:42.560 of physics. One reason we do physics is to help 0:05:42.640 --> 0:05:45.800 answer questions, which, in the end our philosophical what does 0:05:45.839 --> 0:05:47.719 it mean to be alive? Why are we here? What 0:05:47.720 --> 0:05:49.760 should we do with our lives? How do we make 0:05:49.800 --> 0:05:52.640 sense of this cosmos? Those aren't science questions, but the 0:05:52.680 --> 0:05:56.080 answers to science questions can help us understand how to 0:05:56.160 --> 0:05:59.760 tackle those other more difficult philosophical questions. Yeah, because I 0:05:59.760 --> 0:06:03.000 guess it is a pretty incredible universe, and even though 0:06:03.040 --> 0:06:05.400 we may want to understand how it all works, there's 0:06:05.440 --> 0:06:08.000 still sort of the questions that you can ask beyond that, 0:06:08.120 --> 0:06:11.360 beyond physics, right, like what does it mean? Or why 0:06:11.400 --> 0:06:13.560 are we here? And some of those questions are really 0:06:13.600 --> 0:06:16.840 simple signing questions, the kind of questions you often ask 0:06:16.920 --> 0:06:19.159 me when I start talking about something complicated and you're like, 0:06:19.200 --> 0:06:21.839 hold on, back up, what are we even talking about? 0:06:21.920 --> 0:06:25.599 Can you give me a definition of space or mass? 0:06:26.000 --> 0:06:28.400 What are these things we're talking about? Do we really 0:06:28.520 --> 0:06:30.880 understand them? Yeah, because I guess you know, you grew 0:06:30.960 --> 0:06:33.000 up in this universe and maybe you become a physicist 0:06:33.120 --> 0:06:35.680 or not, but you still kind of study it, and you, 0:06:35.680 --> 0:06:37.360 you know, you start to take things a little bit 0:06:37.360 --> 0:06:39.320 for granted, you know, in a way, you know, you know, 0:06:39.360 --> 0:06:41.919 we think about the fact that we walk around on 0:06:42.000 --> 0:06:43.880 this planet, but why are we stuck to this planet 0:06:43.880 --> 0:06:45.839 at all and not floating out there in space. Yeah, 0:06:45.880 --> 0:06:47.920 it's a really important exercise to take a step back 0:06:47.960 --> 0:06:50.240 and say, what is this thing we're talking about, What 0:06:50.279 --> 0:06:52.120 does it really mean? What do we know about it? 0:06:52.360 --> 0:06:54.920 What can we learn about the nature of the universe 0:06:55.200 --> 0:06:58.320 from what we know about how these physical processes happen. Yeah, 0:06:58.360 --> 0:07:01.000 it always amazes me that there are basic concepts and 0:07:01.040 --> 0:07:04.320 physics that physicists don't really have a good definition for 0:07:04.520 --> 0:07:06.520 or a good explanation for. You know, we've covered a 0:07:06.520 --> 0:07:08.320 lot of them in our book. We have No Idea 0:07:08.440 --> 0:07:10.920 a guide to the Unknown Universe. But it's still amazing 0:07:10.920 --> 0:07:12.960 that there are things that even we didn't cover in 0:07:13.000 --> 0:07:16.320 the book that physicists still struggle to define. You don't 0:07:16.360 --> 0:07:19.560 have to know what you're talking about to sometimes accomplish 0:07:19.600 --> 0:07:22.520 something in physics. The most famous example is quantum mechanics. 0:07:22.720 --> 0:07:25.160 Nobody really understands what it means, but we can do 0:07:25.240 --> 0:07:30.040 really complicated, really accurate calculations and predictions using quantum mechanics, 0:07:30.040 --> 0:07:33.320 even if we don't quite grasp what exactly is going on. Yeah, 0:07:33.560 --> 0:07:36.720 and maybe out of all those basic concepts about the universe, 0:07:36.760 --> 0:07:41.920 there are maybe none more basic than the idea of energy. 0:07:42.160 --> 0:07:45.920 That seems like a super duper basic concept in physics. 0:07:46.080 --> 0:07:47.600 It is, in fact, and it's something a lot of 0:07:47.640 --> 0:07:49.800 listeners over the years have written in to ask us 0:07:49.840 --> 0:07:51.920 to talk about so to the on the podcast will 0:07:51.960 --> 0:08:00.680 be tackling the question what is energy? And where can 0:08:00.720 --> 0:08:04.400 we get some more of it? Yeah? That's not coming 0:08:04.440 --> 0:08:07.680 from a coffee cup maybe or dead plants underground. But 0:08:07.760 --> 0:08:09.520 it is kind of sort of an interesting question, I 0:08:09.560 --> 0:08:11.760 think because it's so short, right, Like, this is one 0:08:11.800 --> 0:08:14.640 of the shortest questions we've tackled in a long time 0:08:14.680 --> 0:08:17.800 on this podcast. It's just three words, what is energy? 0:08:18.120 --> 0:08:22.040 Maybe we should add a fourth one man, what is energy? Man? 0:08:22.600 --> 0:08:27.720 What is energy? Anyway? Or maybe what? I guess we 0:08:27.720 --> 0:08:31.960 could go deeper, we go what is Eventually we'll just 0:08:32.000 --> 0:08:35.280 be asking the question what. Maybe that's all physics and 0:08:35.320 --> 0:08:39.360 philosophy is just responding to the universe and going what. Yeah, 0:08:39.800 --> 0:08:41.760 but then we will, you know, like a Marvel movie 0:08:41.800 --> 0:08:50.199 will find another sequel. We'll go with where or Speechless 0:08:50.200 --> 0:08:53.040 the new seel. But it is a really simple sounding 0:08:53.160 --> 0:08:55.840 question with a lot of subtle nuances, which is why 0:08:55.840 --> 0:08:57.640 it took us a little while to figure out how 0:08:57.720 --> 0:09:00.120 to attack it. It's a short question without an the 0:09:00.240 --> 0:09:02.480 simple answer. Yeah, I was thinking about this word and 0:09:02.600 --> 0:09:05.679 it's kind of interesting. Because I think everyone you know 0:09:05.679 --> 0:09:08.320 knows the word obviously energy and has something you know, 0:09:08.440 --> 0:09:11.240 some some intuitous sense attached to it. But you know, 0:09:11.280 --> 0:09:13.160 if you sort of think about what is it, it's 0:09:13.200 --> 0:09:15.760 kind of hard to define. Yeah, you're used to talking 0:09:15.760 --> 0:09:17.680 about it, you think about it in your life, you 0:09:17.800 --> 0:09:20.199 pay for it, you use it. But if you sit 0:09:20.280 --> 0:09:22.400 on your couch late at night and wonder, like, what 0:09:22.600 --> 0:09:24.600 is it? Has seems to have so many forms, they 0:09:24.600 --> 0:09:26.920 can transform back and forth into each other. It's a 0:09:27.000 --> 0:09:29.559 vital part of the universe. It feels like it should 0:09:29.559 --> 0:09:32.400 be something fundamental. But is a physical thing? Is it 0:09:32.520 --> 0:09:36.040 just a calculation that we do? Is it a philosophical question? 0:09:36.440 --> 0:09:38.720 It's a really hard thing to grapple with. Yeah, and 0:09:38.760 --> 0:09:41.320 even physicists in their textbooks have sort of a hard 0:09:41.360 --> 0:09:43.040 time pinning this down right. I mean, there is sort 0:09:43.040 --> 0:09:46.400 of an official definition of it, right as the capacity 0:09:46.440 --> 0:09:49.079 to do work. Yeah, there is that definition. But then 0:09:49.120 --> 0:09:51.640 you look at the official definition of work and its 0:09:51.920 --> 0:09:59.560 energy transfer a lot, it moves back on itself, like inception, Yeah, exactly, 0:09:59.720 --> 0:10:03.880 deaf nisition ce definition. So energy is defined in terms 0:10:03.880 --> 0:10:05.839 of work, and work is defined in terms of energy, 0:10:05.920 --> 0:10:10.520 So like, what is this thing we're talking about. Wow. Interesting, Yeah, 0:10:10.559 --> 0:10:13.320 because I guess that's the only way we know how 0:10:13.320 --> 0:10:16.079 to define it. Kind of maybe, sort of, And you 0:10:16.120 --> 0:10:19.720 have to grapple with the subtlety between physics definitions like 0:10:19.800 --> 0:10:23.600 what we technically mean by work and our intuitive understanding 0:10:23.640 --> 0:10:27.840 of these concepts, because physics often repurposes a word that 0:10:28.000 --> 0:10:31.280 everybody uses a normal language to mean something very specific 0:10:31.360 --> 0:10:36.280 and technical. For physics, that's true for example for work. Interesting. Well, 0:10:36.360 --> 0:10:38.559 let's start to dig into this, but first, as usually, 0:10:38.640 --> 0:10:40.880 we're wondering how many people out there have thought about 0:10:40.920 --> 0:10:43.719 this very basic question and how many people out there 0:10:43.840 --> 0:10:46.319 think they know the answer to this. So thanks very 0:10:46.360 --> 0:10:50.000 much to everybody who volunteered to answer difficult, random questions 0:10:50.040 --> 0:10:53.440 from an internet physicist. I really appreciate your work. And 0:10:53.480 --> 0:10:55.320 if you're out there and have been listening to the 0:10:55.360 --> 0:10:58.120 podcast and want to put your roove always to these questions, 0:10:58.160 --> 0:11:01.080 please don't be shy. Send me an email two questions 0:11:01.120 --> 0:11:03.800 at Daniel and Jorge dot com. Think about it for 0:11:03.800 --> 0:11:07.160 a second. What do you think energy is or how 0:11:07.200 --> 0:11:10.400 would you explain it? Here's what people had to say. Um, 0:11:10.400 --> 0:11:13.320 I remember learning in maybe high school physics that energy 0:11:13.720 --> 0:11:16.920 is the ability for something to do work. UM. I 0:11:16.960 --> 0:11:19.280 think that that's probably not nuanced enough of a definition. 0:11:19.679 --> 0:11:22.240 More nuanced way to look at it might be it's 0:11:22.320 --> 0:11:25.960 um something's ability to affect change, which doesn't necessarily have 0:11:26.040 --> 0:11:29.240 to be work, and sort of like the classic physics definition. 0:11:29.720 --> 0:11:33.760 I think energy is truly just a vibration, and the 0:11:33.880 --> 0:11:41.160 energy potential is dictated by the field the vibration or 0:11:41.240 --> 0:11:46.480 string sits with him. I've asked this question to someone 0:11:46.480 --> 0:11:49.200 who knew a lot about physics before, and their answer 0:11:49.280 --> 0:11:51.760 was not useful to me. What I came away with 0:11:51.880 --> 0:11:55.240 is like energy is potential for things to happen, and 0:11:55.400 --> 0:11:58.320 concentrations of that potential, and it's expressed in a lot 0:11:58.360 --> 0:12:00.880 of ways. This feels like it should be one of 0:12:00.880 --> 0:12:05.240 those like really easy questions to answer fifth graders should 0:12:05.240 --> 0:12:09.160 know this or something, but I'm having trouble explaining it. 0:12:09.160 --> 0:12:15.880 It is a force like but needed to create force. 0:12:16.280 --> 0:12:18.000 I mean, I think of going down to like the 0:12:18.000 --> 0:12:25.320 atomic level. Energy is like the movement of electrons. Intuitively, 0:12:25.840 --> 0:12:30.760 when I think of energy, I think about vibrating particles 0:12:30.320 --> 0:12:34.840 and the fast of their vibrating more energy they have. 0:12:35.040 --> 0:12:39.640 But I guess at a more fundamental level energy is 0:12:39.720 --> 0:12:44.840 about probably fields and like how much energy is in 0:12:45.400 --> 0:12:49.040 a certain field, dictating what kind of particle is and 0:12:49.240 --> 0:12:51.640 what that particle is doing. I think energy is just 0:12:51.679 --> 0:12:55.079 like tiny movement of particles that gets passed along from 0:12:55.080 --> 0:12:57.880 particle to particle. Energy is the opposite side of the 0:12:57.920 --> 0:13:01.240 coin is mass. But my us as you're referring to 0:13:01.280 --> 0:13:03.840 the fundamental building blocks of energy, and I'm not sure 0:13:03.840 --> 0:13:07.080 what those could be. All Right, interesting answers um pretty 0:13:07.120 --> 0:13:08.839 deep ones to a lot of people are like, it's 0:13:08.840 --> 0:13:13.199 a vibe, man, it's a mood. Yeah, And some people 0:13:13.240 --> 0:13:16.960 giving examples of what energy is and some people talking 0:13:17.000 --> 0:13:19.400 about the different forms of it. It's the really interesting 0:13:19.400 --> 0:13:22.080 answers here. Thanks everyone. Yeah, and some people even sort 0:13:22.080 --> 0:13:24.439 of went with the official definition, which is that it's 0:13:24.480 --> 0:13:27.520 related to your ability to do work or to make 0:13:27.559 --> 0:13:29.880 work or change work. But did did you follow up 0:13:29.880 --> 0:13:33.559 with them? Then? What does work mean? No? I don't 0:13:33.559 --> 0:13:36.360 actually have live conversations with these folks. It's just the email. 0:13:36.520 --> 0:13:38.480 When I do interviews on campus, then I can ask 0:13:38.520 --> 0:13:41.079 fun follow up questions like does that scare you? Are 0:13:41.120 --> 0:13:43.839 you worried about that? But here I just give them 0:13:43.840 --> 0:13:47.679 the one shot I see, I see, I see. You're 0:13:47.720 --> 0:13:50.800 trying to still fear in them. No, I try to 0:13:50.840 --> 0:13:53.520 be friendly and not instill fear in them over email 0:13:53.520 --> 0:13:55.640 in person. Yeah, absolutely, I'll put them on the spot. 0:13:57.480 --> 0:13:59.839 All right, Well, it's a tricky subject, and I think 0:13:59.840 --> 0:14:03.240 I will find out it's something that has some deep 0:14:03.280 --> 0:14:07.160 mysteries about it, right, It's not an easy answer answer. 0:14:07.360 --> 0:14:09.640 All right, Well, Daniel step us through. What are some 0:14:09.720 --> 0:14:11.760 of the first things that physicists think of when they 0:14:11.760 --> 0:14:14.040 think of energy? So right off the bat, we should 0:14:14.040 --> 0:14:18.400 just admit that we don't fundamentally know what energy is. Wait, 0:14:18.440 --> 0:14:22.520 what we're done with the podcast? Nobody knows that's it. 0:14:24.240 --> 0:14:26.520 You know some things about it, We figured some things out. 0:14:26.920 --> 0:14:28.720 You can use those to piece together a picture of 0:14:28.800 --> 0:14:31.280 what it might be and what that means, But fundamentally 0:14:31.280 --> 0:14:35.280 it remains a philosophical mystery what energy is. First, maybe 0:14:35.320 --> 0:14:37.200 I should put the question back on you and ask, like, 0:14:37.560 --> 0:14:40.080 what kind of answer do people expect? Like what kind 0:14:40.080 --> 0:14:42.840 of answer would be satisfying? Where is the sort of 0:14:43.000 --> 0:14:45.640 nature of the question we're even asking? Do you want 0:14:45.640 --> 0:14:48.400 to know if energy is like a thing that flows 0:14:48.520 --> 0:14:51.360 or if it's made out of little energy ons? Or 0:14:51.520 --> 0:14:55.360 just like a concise definition of what this thing is. Well, 0:14:55.400 --> 0:14:57.440 I mean you sort of give it away. He kind 0:14:57.440 --> 0:15:00.320 of spoiled the answer for me here and seem to 0:15:00.320 --> 0:15:01.960 not want to try. I mean, if you guys don't 0:15:01.960 --> 0:15:04.960 know what it is, what I know. But it's kind 0:15:04.960 --> 0:15:07.160 of an interesting question. I think, you know, at the 0:15:07.240 --> 0:15:09.680 base of it, I think most people think of energy 0:15:09.840 --> 0:15:12.880 is like the opposite of of not moving, you know 0:15:12.920 --> 0:15:15.840 what I mean, Like it's the opposite of standing still 0:15:15.880 --> 0:15:18.720 and not doing anything. Like if you have energy, then 0:15:18.760 --> 0:15:21.560 you're doing something, You're doing work, I guess, yeah. And 0:15:21.600 --> 0:15:24.680 I think that a lot of the concepts about energy 0:15:24.800 --> 0:15:27.280 start from examples. I think some of the difficulty comes 0:15:27.280 --> 0:15:28.800 from the fact that you can put lots of different 0:15:28.880 --> 0:15:31.480 kinds of examples together and then wonder, like what do 0:15:31.560 --> 0:15:34.080 they all have in common? You know, the mass is 0:15:34.200 --> 0:15:36.000 energy or this is energy, Then what do they all 0:15:36.080 --> 0:15:38.720 have in common? And so maybe we should start with 0:15:38.760 --> 0:15:40.720 sort of like the history of the idea of the 0:15:40.760 --> 0:15:44.240 development of energy, how people discover different forms of energy 0:15:44.320 --> 0:15:47.440 and then talk about the common thread between them. Yeah, yeah, sure, 0:15:47.520 --> 0:15:49.200 well I was thinking kind of it's kind of like 0:15:49.200 --> 0:15:53.200 maybe the opposite of the phrase nothing happens. Like if 0:15:53.240 --> 0:15:57.240 nothing happens, ever, then there's no energy, but if things happen, 0:15:57.680 --> 0:16:00.440 then there's energy. It's like maybe related to the word happening, 0:16:00.600 --> 0:16:03.000 that's possibly true, but there are subtle wrinkles there, like 0:16:03.040 --> 0:16:05.520 you can have a universe with a lot of energy 0:16:05.560 --> 0:16:08.880 but no free energy, like the heat death of the universe. 0:16:08.960 --> 0:16:11.280 Nothing can really happen. But there is a lot of 0:16:11.400 --> 0:16:14.280 energy in the universe, there's just none available to do 0:16:14.320 --> 0:16:18.040 work because there's no energy gradients. So there are different 0:16:18.080 --> 0:16:21.280 kinds of energy, different kinds of energy. And fundamentally, the 0:16:21.320 --> 0:16:23.920 game we're playing here is that we're looking around in 0:16:23.960 --> 0:16:27.240 the universe and we're coming up with ways to do calculations, 0:16:27.280 --> 0:16:30.920 and we're wondering do those mean anything? And energy in 0:16:30.960 --> 0:16:34.000 that sense isn't like something physical. It's an observation we 0:16:34.080 --> 0:16:36.640 make about the universe. Like I can look at a 0:16:36.640 --> 0:16:39.520 physical system, you know, the Earth moving around the Sun, 0:16:40.080 --> 0:16:41.960 and I can do a calculation that could say, well, 0:16:42.040 --> 0:16:44.440 I'm going to define some quantity. I call it energy, 0:16:44.680 --> 0:16:47.240 And here's how I calculated. I take the velocity I'm 0:16:47.280 --> 0:16:49.760 multiplied by the mass. I add this, I add that 0:16:49.760 --> 0:16:52.560 that's the something I invented call it energy. And most 0:16:52.600 --> 0:16:54.880 of the time, if you just invent a quantity, it's 0:16:54.920 --> 0:16:57.760 not interesting or useful, doesn't reveal anything about the universe. 0:16:58.000 --> 0:17:00.880 But sometimes it does, and it was especially when it 0:17:00.920 --> 0:17:03.600 seems like it might be conserved when you've constructed this 0:17:03.720 --> 0:17:07.040 quantity which seems to like not change as time goes 0:17:07.080 --> 0:17:10.119 on through the universe. Mm hmmmm. Well, that's an interesting 0:17:10.160 --> 0:17:12.720 concept to think about. How they came up how humans 0:17:12.760 --> 0:17:14.320 came up with the word, right, Like, did we come 0:17:14.359 --> 0:17:18.000 up with that word for energy before science even you 0:17:18.040 --> 0:17:19.520 know what I mean? Like that? I wonder if Caveman 0:17:19.880 --> 0:17:23.120 had a phrase or a word for this idea of 0:17:23.280 --> 0:17:26.560 things happening or energy. I think Caveman had teenagers, and 0:17:26.600 --> 0:17:28.760 teenagers didn't get out of the cave very early in 0:17:28.800 --> 0:17:31.119 the morning, and people wondered if they needed more energy. 0:17:31.160 --> 0:17:34.040 I'm sure that you know the intuitive concept of feeling 0:17:34.080 --> 0:17:36.960 like you have energy or you're tired. That's an age 0:17:37.000 --> 0:17:40.760 old idea for sure. M So we probably had a 0:17:40.800 --> 0:17:43.520 word for it, and then people started to use it 0:17:43.560 --> 0:17:47.320 in physics. Yeah, and scientifically, one of the first concepts 0:17:47.320 --> 0:17:50.240 that was developed was kinetic energy. So you've got to 0:17:50.240 --> 0:17:53.879 go back to people like Leibnitz. It was Newton's contemporary 0:17:54.040 --> 0:17:56.960 and you know, also developed calculus, and like Newton, he 0:17:57.000 --> 0:17:59.680 also did a bit of physics, right, And the Leibnitz 0:17:59.720 --> 0:18:02.240 note us that things moved, that there's motion. And he 0:18:02.280 --> 0:18:06.800 came up with this quantity mass times velocity times velocity again, 0:18:07.000 --> 0:18:10.320 so MV squared, And he said, this thing seems to 0:18:10.359 --> 0:18:14.199 be conserved. He called this thing vis visa, like a 0:18:14.240 --> 0:18:18.960 living force, and so he essentially stumbled across the definition 0:18:18.960 --> 0:18:21.600 of kinetic energy and said, hey, here's a quantity which 0:18:21.640 --> 0:18:23.920 is interesting because it seems to be conserved. It seems 0:18:24.040 --> 0:18:27.280 like as time passes and you recalculate this quantity, it 0:18:27.359 --> 0:18:29.960 doesn't change, right. But I guess maybe a question is 0:18:29.960 --> 0:18:33.200 how did he noticed that it was conserved? Like why 0:18:33.240 --> 0:18:36.399 did he pick MV squared? As the quantity that was 0:18:36.400 --> 0:18:39.119 concerned was just something specific he was studying. He didn't 0:18:39.160 --> 0:18:41.400 know why. He was just sort of like playing around. 0:18:41.560 --> 0:18:43.920 You know, it's sort of like a discovery in mathematics, 0:18:44.000 --> 0:18:45.600 But what do you mean it playing around around with 0:18:45.640 --> 0:18:47.879 what you know? At that time, people didn't understand motion. 0:18:48.200 --> 0:18:51.280 Newton hadn't developed his laws yet, so people would just 0:18:51.320 --> 0:18:53.920 like multiplying random stuff together and seeing what it could do. 0:18:54.320 --> 0:18:56.800 You know, there's not that many ways to combine basic 0:18:56.880 --> 0:19:00.160 quantities mass and velocity in these things, and so it's 0:19:00.160 --> 0:19:02.080 not that hard to study them. You know, across the 0:19:02.119 --> 0:19:06.159 English channel, Newton was studying momentum, mass, time, velocity. So 0:19:06.280 --> 0:19:09.120 likeness has just multiplied it by velocity one more time. 0:19:09.240 --> 0:19:12.280 I'm sure he studied other quantities like mass squared times 0:19:12.280 --> 0:19:15.640 of loss that didn't have any interesting properties. You make 0:19:15.640 --> 0:19:17.159 it sound like a bunch of monkeys in a in 0:19:17.200 --> 0:19:19.840 an infinite room piping that typewriter. It's a bunch of 0:19:19.840 --> 0:19:22.000 grass students in an infinite room, and they all come 0:19:22.119 --> 0:19:24.080 with one quantity and they're like, oh, this one's not interesting. 0:19:24.080 --> 0:19:26.200 Oh look at this one. This one seems to be conserved. 0:19:26.240 --> 0:19:28.840 I wonder what that means, but I guess, I mean, like, 0:19:28.960 --> 0:19:31.399 what did he see it conserved in? Do you know 0:19:31.400 --> 0:19:33.720 what I mean? Like he calculated in for one thing 0:19:33.760 --> 0:19:36.119 and then for another, and then he saw that it 0:19:36.160 --> 0:19:38.840 was the same. I guess, But what was that thing? Yes, So, 0:19:38.880 --> 0:19:41.399 for example, physicists of this age like to do calculations 0:19:41.400 --> 0:19:44.560 about billiard balls. Right now, billiards is a very very 0:19:44.560 --> 0:19:46.960 old game. So you can take the kinetic energy of 0:19:47.000 --> 0:19:49.120 the first ball and then it hits another one, maybe 0:19:49.160 --> 0:19:51.159 it has a different mass, but you notice that the 0:19:51.240 --> 0:19:54.879 kinetic energy is conserved, and so you can do simple 0:19:54.880 --> 0:19:57.679 calculations there and see that kinetic energy is conserved in 0:19:57.720 --> 0:20:02.080 these systems, so like after a collision. Then they noticed 0:20:02.119 --> 0:20:04.960 that this quantity seems to stay the same, Like you 0:20:05.000 --> 0:20:07.399 added up at the beginning for the two balls, and 0:20:07.440 --> 0:20:09.200 then you added up at the end for the two balls, 0:20:09.240 --> 0:20:11.480 and it seemed to be the same. Is that what happened, 0:20:11.480 --> 0:20:13.480 because if you look at the velocities, the velocities don't 0:20:13.480 --> 0:20:15.440 stay the same. That's right. The velocities do not stay 0:20:15.480 --> 0:20:17.800 the same unless the two masses are the same. But 0:20:17.920 --> 0:20:20.959 like the really slow moving massive ball bumps into a 0:20:21.080 --> 0:20:23.640 very light ball, a low mass ball, that low mass 0:20:23.640 --> 0:20:26.240 ball will fly off at higher speeds, and so you're write, 0:20:26.320 --> 0:20:29.480 velocity isn't conserved. But this weird combination of mass and 0:20:29.600 --> 0:20:32.800 velocity squared did seem to be conserved. So that was 0:20:32.800 --> 0:20:35.440 sort of like an experimental discovery that lenn has made. 0:20:35.880 --> 0:20:38.520 And you know, this idea of conservation means it might 0:20:38.560 --> 0:20:41.320 be something important, It might be something like fundamental to 0:20:41.400 --> 0:20:44.199 the universe. It's like, there's the philosophy aspect to it. Right, 0:20:44.480 --> 0:20:46.760 just because something is conserved, why do we care? Because 0:20:46.760 --> 0:20:49.680 it reveals something about the inner workings of the universe. 0:20:49.720 --> 0:20:52.680 I think about this sometimes an analogy to other systems, 0:20:52.720 --> 0:20:55.639 like economics, or like the water system. You know, like 0:20:55.880 --> 0:20:58.680 water goes through lots of different forms. It rains into 0:20:58.720 --> 0:21:00.800 the ocean and evaporates back up in the clouds, that 0:21:00.880 --> 0:21:03.199