1 00:00:16,649 --> 00:00:20,086 This is unbelievable. 2 00:00:20,086 --> 00:00:26,593 So I just learned that YFN means your friendly neighborhood 3 00:00:26,593 --> 00:00:28,461 hackers. 4 00:00:28,461 --> 00:00:30,296 And look, we brought it with us. 5 00:00:30,296 --> 00:00:31,631 Unbelievable. 6 00:00:31,631 --> 00:00:32,564 This is making my day. 7 00:00:32,564 --> 00:00:33,500 This is making my week. 8 00:00:33,500 --> 00:00:35,435 This is incredible. 9 00:00:35,435 --> 00:00:38,304 And really, I don't know what to say. 10 00:00:38,304 --> 00:00:39,539 This is amazing. 11 00:00:39,539 --> 00:00:42,575 So whoever you are, thank you. 12 00:00:42,575 --> 00:00:43,410 This is awesome. 13 00:00:43,410 --> 00:00:49,582 So where's Laura? 14 00:00:49,582 --> 00:00:53,520 So Laura, next year I think we should give every student 15 00:00:53,520 --> 00:00:55,522 one of these. 16 00:00:55,522 --> 00:00:57,157 This will be in our-- 17 00:00:57,157 --> 00:00:58,758 so we've got some candy. 18 00:00:58,758 --> 00:01:00,593 We've got T-shirts. 19 00:01:00,593 --> 00:01:03,129 We'll get to those. 20 00:01:03,129 --> 00:01:05,999 We've got welcome to the last lecture. 21 00:01:05,999 --> 00:01:07,233 Oh, there's some T-shirts. 22 00:01:07,233 --> 00:01:09,069 We're going to let TAs throw them out. 23 00:01:09,069 --> 00:01:10,637 We're going to let TAs throw them out. 24 00:01:14,374 --> 00:01:20,580 But you guys got a-- 25 00:01:25,185 --> 00:01:32,459 so we got a little bit more to cover on diffusion. 26 00:01:32,459 --> 00:01:34,094 I got a why this matters, and then I 27 00:01:34,094 --> 00:01:38,898 got a couple of things I want to say, and then we'll conclude. 28 00:01:38,898 --> 00:01:42,001 And like I said, the plan today is 29 00:01:42,001 --> 00:01:46,239 to conclude a little early to give you time to fill out 30 00:01:46,239 --> 00:01:47,941 the course evaluations. 31 00:01:47,941 --> 00:01:50,310 We really take this seriously. 32 00:01:50,310 --> 00:01:57,050 We really value any and all input that you have. 33 00:01:57,050 --> 00:01:58,151 And so please do. 34 00:01:58,151 --> 00:02:01,121 If you haven't done it already, please use the last 15 minutes 35 00:02:01,121 --> 00:02:04,190 that we'll give you in the class to fill those out. 36 00:02:04,190 --> 00:02:05,458 It means a lot to us. 37 00:02:09,095 --> 00:02:13,032 This is still-- it's hitting me right here. 38 00:02:13,032 --> 00:02:14,234 It's slowing me down. 39 00:02:17,036 --> 00:02:17,937 I can do it. 40 00:02:17,937 --> 00:02:19,105 I'm going to get through it. 41 00:02:21,474 --> 00:02:24,577 So we were talking about Fick's laws, 42 00:02:24,577 --> 00:02:28,081 and you're only going to be tested on the first one, 43 00:02:28,081 --> 00:02:31,918 but I do want to tell you about the second one. 44 00:02:31,918 --> 00:02:33,953 You are not going to be tested on the second one. 45 00:02:33,953 --> 00:02:36,890 That is correct, unlike last year. 46 00:02:36,890 --> 00:02:39,359 Because we didn't have time to get the lecture 47 00:02:39,359 --> 00:02:41,461 in on the second law before the recitation, 48 00:02:41,461 --> 00:02:42,328 which was yesterday. 49 00:02:42,328 --> 00:02:47,466 And so look, there will probably will be a diffusion problem, 50 00:02:47,466 --> 00:02:48,668 but not on the second law. 51 00:02:48,668 --> 00:02:52,138 But still, I do want to finish the example, 52 00:02:52,138 --> 00:02:53,640 and I won't go through it in detail, 53 00:02:53,640 --> 00:02:55,275 but I want to set it up and just show it 54 00:02:55,275 --> 00:02:59,946 to so you have a sense of what Fick's second law lets you do. 55 00:02:59,946 --> 00:03:04,884 And we ended with the first law, and I wrote the second line 56 00:03:04,884 --> 00:03:05,385 down. 57 00:03:05,385 --> 00:03:07,053 Now, the first law, that is something I 58 00:03:07,053 --> 00:03:08,021 want you to know about. 59 00:03:08,021 --> 00:03:10,590 And so remember, with the first law, 60 00:03:10,590 --> 00:03:16,629 so let me go over here so you have a whole board to use. 61 00:03:16,629 --> 00:03:21,734 So in Fick's first law, what that meant was 62 00:03:21,734 --> 00:03:26,539 it's a law that describes the steady state. 63 00:03:26,539 --> 00:03:30,043 So Fick's first law was steady state. 64 00:03:30,043 --> 00:03:34,447 And this is now bringing back memories from two days ago, 65 00:03:34,447 --> 00:03:44,123 so steady state, which means no time dependents, no time 66 00:03:44,123 --> 00:03:45,692 dependents. 67 00:03:45,692 --> 00:03:48,127 And so we had some examples of that. 68 00:03:48,127 --> 00:03:49,028 In the law itself-- 69 00:03:49,028 --> 00:03:50,063 I'll write it down here-- 70 00:03:50,063 --> 00:03:55,535 was that the flux is equal to minus this diffusion constant 71 00:03:55,535 --> 00:04:01,574 times the change in concentration 72 00:04:01,574 --> 00:04:02,575 over some distance. 73 00:04:02,575 --> 00:04:07,280 And so we had this example of a membrane right, 74 00:04:07,280 --> 00:04:11,150 and so you could imagine we had the glove. 75 00:04:11,150 --> 00:04:14,621 It was the remember, the butyl glove. 76 00:04:14,621 --> 00:04:16,055 And so we had some distance. 77 00:04:16,055 --> 00:04:19,993 Maybe this is like a delta x, and there 78 00:04:19,993 --> 00:04:25,198 was some concentration up here, C1, and some concentration down 79 00:04:25,198 --> 00:04:27,700 here, C2. 80 00:04:27,700 --> 00:04:29,469 Now the key in Fick's law is you're 81 00:04:29,469 --> 00:04:30,903 going to hold these concentrations 82 00:04:30,903 --> 00:04:34,941 constant at the source, at each of these points. 83 00:04:34,941 --> 00:04:37,010 And so you can imagine that it's going 84 00:04:37,010 --> 00:04:38,411 to change as you go down the hill, 85 00:04:38,411 --> 00:04:42,015 and we frame this in terms of Brownian motion. 86 00:04:42,015 --> 00:04:45,084 We're able to understand why concentration, 87 00:04:45,084 --> 00:04:48,254 why diffusion happens down a concentration gradient. 88 00:04:52,925 --> 00:04:54,994 Now that flux, that flux. 89 00:04:54,994 --> 00:04:55,495 Remember. 90 00:04:55,495 --> 00:05:06,172 So J is an amount divided by an area times time. 91 00:05:06,172 --> 00:05:09,709 That's J. That's the flux through the membrane, 92 00:05:09,709 --> 00:05:14,314 and that is also going to be constant. 93 00:05:14,314 --> 00:05:21,321 Now, the d, what we assumed in the d is that it's a constant. 94 00:05:21,321 --> 00:05:22,989 So in the Fick's first law problems, 95 00:05:22,989 --> 00:05:27,994 we often assume d doesn't depend on concentration. 96 00:05:27,994 --> 00:05:30,763 So that means that if I'm over here at a high concentration, 97 00:05:30,763 --> 00:05:34,233 I'm over here at a low concentration, well then-- 98 00:05:34,233 --> 00:05:36,135 by the way, this would be like-- 99 00:05:36,135 --> 00:05:37,203 oh. 100 00:05:37,203 --> 00:05:39,105 Would you like some candy? 101 00:05:39,105 --> 00:05:40,106 I would like some candy. 102 00:05:40,106 --> 00:05:40,873 Thank you very much. 103 00:05:40,873 --> 00:05:42,008 Do you mind if we walk up and down the aisles? 104 00:05:42,008 --> 00:05:42,675 No, not at all. 105 00:05:42,675 --> 00:05:42,942 No. 106 00:05:42,942 --> 00:05:43,443 Please do. 107 00:05:43,443 --> 00:05:44,143 Yeah. 108 00:05:44,143 --> 00:05:45,411 That's awesome. 109 00:06:05,098 --> 00:06:07,934 This is just getting better. 110 00:06:07,934 --> 00:06:11,204 I'm feeling less and less like talking about Fick's law, 111 00:06:11,204 --> 00:06:13,473 but here we are. 112 00:06:13,473 --> 00:06:14,207 I'll go fast. 113 00:06:18,978 --> 00:06:26,919 Now the thing is, look, this is x. 114 00:06:26,919 --> 00:06:28,321 By the way, I really want to know 115 00:06:28,321 --> 00:06:32,191 where they got the costumes from, but this is x, 116 00:06:32,191 --> 00:06:34,060 and this would be like the concentration. 117 00:06:38,131 --> 00:06:42,402 Now d could depend on concentration. 118 00:06:42,402 --> 00:06:44,303 By the way, it's actually quite interesting. 119 00:06:44,303 --> 00:06:47,006 It does have a small dependence on concentration. 120 00:06:47,006 --> 00:06:49,041 We often don't include it. 121 00:06:49,041 --> 00:06:51,911 So this would be like a straight line. 122 00:06:51,911 --> 00:06:56,149 But if it did, if it did depend on concentration, 123 00:06:56,149 --> 00:06:57,950 then you might have a deviation. 124 00:06:57,950 --> 00:06:59,919 You could have something like this, 125 00:06:59,919 --> 00:07:01,521 or you could have something like that, 126 00:07:01,521 --> 00:07:03,589 and you don't need to have a straight line 127 00:07:03,589 --> 00:07:04,490 to use Fick's law. 128 00:07:04,490 --> 00:07:06,325 But in a lot of the problems that we do, 129 00:07:06,325 --> 00:07:09,061 we assume d is just independent of concentration. 130 00:07:09,061 --> 00:07:09,729 It's a constant. 131 00:07:14,600 --> 00:07:18,571 So I'm adding more and more carbon into iron. 132 00:07:18,571 --> 00:07:22,207 Does the diffusion of the carbon now depend on how much I added? 133 00:07:22,207 --> 00:07:24,444 Well, yeah, it might a little bit. 134 00:07:24,444 --> 00:07:27,713 By the way, that doesn't mean that it depends on time. 135 00:07:27,713 --> 00:07:30,349 That's the distinction I want to make. 136 00:07:30,349 --> 00:07:32,985 So again, the problems we do with Fick's law, 137 00:07:32,985 --> 00:07:35,788 we'll assume d doesn't depend on concentration. 138 00:07:35,788 --> 00:07:37,290 We'll just assume it's a constant, 139 00:07:37,290 --> 00:07:39,258 but the main determining factor to see 140 00:07:39,258 --> 00:07:42,228 if it's a Fick's second law or Fick's first law problem 141 00:07:42,228 --> 00:07:44,764 isn't whether d changes with concentration. 142 00:07:44,764 --> 00:07:45,364 No. 143 00:07:45,364 --> 00:07:47,967 It's whether there's a time dependence. 144 00:07:47,967 --> 00:07:49,669 It's whether there's a time dependence, 145 00:07:49,669 --> 00:07:55,707 and that was the problem that we left off on on Monday. 146 00:07:55,707 --> 00:07:57,710 We say, well, you've got to do this thing called 147 00:07:57,710 --> 00:07:59,645 case-hardening to a lot of materials. 148 00:07:59,645 --> 00:08:01,013 You make the outside harder. 149 00:08:01,013 --> 00:08:03,683 The inside assets a ductile, otherwise, either it's 150 00:08:03,683 --> 00:08:07,420 not strong enough, or it's too ductile. 151 00:08:07,420 --> 00:08:11,591 It just breaks down either way, or it's too brittle. 152 00:08:11,591 --> 00:08:14,126 So you want a case-harden, and that was our Fick's second law 153 00:08:14,126 --> 00:08:15,461 problem. 154 00:08:15,461 --> 00:08:18,498 And again, I'm just going to kind of set it up. 155 00:08:18,498 --> 00:08:19,932 I'm not going to go through it all. 156 00:08:19,932 --> 00:08:26,539 But in the second law, what you have is an ability now to look 157 00:08:26,539 --> 00:08:27,540 at the time dependent. 158 00:08:27,540 --> 00:08:33,746 So you can imagine if I have position x and concentration C 159 00:08:33,746 --> 00:08:37,783 and I start somewhere here, so I have some source. 160 00:08:37,783 --> 00:08:39,885 That's why we call it Cs. 161 00:08:39,885 --> 00:08:40,686 So what did we do? 162 00:08:40,686 --> 00:08:45,725 We took this piece of steel, and we asked the question. 163 00:08:45,725 --> 00:08:49,061 I'm case-hardening the steel, so this is iron with carbon. 164 00:08:49,061 --> 00:08:54,133 And I want to put carbon into it but only up to a certain point 165 00:08:54,133 --> 00:08:55,935 in a certain amount. 166 00:08:55,935 --> 00:08:58,271 How do I know how long to put it in the oven? 167 00:08:58,271 --> 00:09:00,306 That's a Fick's second law problem 168 00:09:00,306 --> 00:09:02,108 because it's a time-dependent process, 169 00:09:02,108 --> 00:09:04,110 and I want to know about concentrations 170 00:09:04,110 --> 00:09:06,846 into the piece of iron, into the piece of steel 171 00:09:06,846 --> 00:09:08,281 as a function of time. 172 00:09:08,281 --> 00:09:10,816 So you can answer questions like this with Fick's second law. 173 00:09:10,816 --> 00:09:13,786 So I had it at 0.25% weight percent carbon, 174 00:09:13,786 --> 00:09:15,788 and I carborize the surface. 175 00:09:15,788 --> 00:09:17,690 I carborize only a certain amount of it. 176 00:09:17,690 --> 00:09:21,661 I case-harden it, how long should you keep it in the oven. 177 00:09:21,661 --> 00:09:24,897 And by the way, also what should your carbon, 178 00:09:24,897 --> 00:09:29,235 your concentration of source be on the outside. 179 00:09:29,235 --> 00:09:31,270 And all these things kind of go in. 180 00:09:31,270 --> 00:09:33,439 And so you could imagine if the source is there 181 00:09:33,439 --> 00:09:34,307 and I'm holding-- 182 00:09:34,307 --> 00:09:38,878 maybe I've got some constant, C0, that's the 0.2. 183 00:09:38,878 --> 00:09:42,648 That's the piece of material I started with. 184 00:09:42,648 --> 00:09:43,149 Well. 185 00:09:43,149 --> 00:09:48,421 You can imagine at t0, you've got this. 186 00:09:48,421 --> 00:09:52,358 So this would be time equals t0. 187 00:09:52,358 --> 00:09:54,493 And then as soon as I expose this 188 00:09:54,493 --> 00:09:57,229 to this higher concentration of carbon, 189 00:09:57,229 --> 00:09:58,698 you might have something like this. 190 00:09:58,698 --> 00:10:02,668 So now you've got t1, and now I wait a little bit longer 191 00:10:02,668 --> 00:10:04,737 and it's going to be able to penetrate more in. 192 00:10:04,737 --> 00:10:07,473 So the concentration inside the material 193 00:10:07,473 --> 00:10:11,143 changes as a function of time and so forth. 194 00:10:14,113 --> 00:10:16,082 That's what Fick's second law tells us, 195 00:10:16,082 --> 00:10:21,120 and the second law is basically a heat equation, 196 00:10:21,120 --> 00:10:25,591 which somebody noticed after a lecture yesterday. 197 00:10:25,591 --> 00:10:31,731 And you [? can ?] let's see, dx squared. 198 00:10:31,731 --> 00:10:33,966 So this is a partial differential equation. 199 00:10:36,836 --> 00:10:43,042 But solving it is just talking to our mathematician friends, 200 00:10:43,042 --> 00:10:46,646 and they come back and say that's an error function. 201 00:10:46,646 --> 00:10:48,681 And an error function is just a function, 202 00:10:48,681 --> 00:10:52,251 And It gives us a solution, C, the concentration 203 00:10:52,251 --> 00:10:57,456 at any position and at any time minus the initial concentration 204 00:10:57,456 --> 00:11:01,894 divided by this difference in concentrations 205 00:11:01,894 --> 00:11:04,997 between the source and the initial is going to equal-- 206 00:11:04,997 --> 00:11:05,498 oh, boy. 207 00:11:08,334 --> 00:11:09,835 You'd think I'd have learned. 208 00:11:09,835 --> 00:11:14,073 36 lectures, and I still worked my way into a corner. 209 00:11:17,543 --> 00:11:21,414 I'm going to do the equals this way 1 minus error 210 00:11:21,414 --> 00:11:27,086 function of x over 2 root dt. 211 00:11:30,322 --> 00:11:38,064 That is what you get when you solve Fick's second law. 212 00:11:38,064 --> 00:11:41,967 That is what you get when you solve Fick's second law. 213 00:11:41,967 --> 00:11:45,638 And now the error function is just a function. 214 00:11:45,638 --> 00:11:50,076 You don't need to worry about the details of this. 215 00:11:50,076 --> 00:11:53,145 You can think about it as like any other function. 216 00:11:53,145 --> 00:11:55,848 But one thing that I want to share with you about the error 217 00:11:55,848 --> 00:11:57,550 function is-- 218 00:11:57,550 --> 00:11:59,752 and this is something that, yeah, you're 219 00:11:59,752 --> 00:12:01,387 not going to need it on the exam, 220 00:12:01,387 --> 00:12:04,623 but you might need this in life. 221 00:12:04,623 --> 00:12:10,029 You might get an error function in life, in IRF. 222 00:12:10,029 --> 00:12:12,331 And if you get into IRF, I don't want 223 00:12:12,331 --> 00:12:14,333 you to panic because IRF is just a function, 224 00:12:14,333 --> 00:12:17,002 and it just looks like this. 225 00:12:17,002 --> 00:12:22,942 It just looks like it's a linear plot roughly up to about 0.6. 226 00:12:22,942 --> 00:12:28,314 This trick-- and then it kind of goes up to 1-- 227 00:12:28,314 --> 00:12:29,548 it's just a function. 228 00:12:29,548 --> 00:12:30,449 Is that 1? 229 00:12:30,449 --> 00:12:32,318 Yeah. 230 00:12:32,318 --> 00:12:39,692 And so if z is less than 0.6 then the error a function of z 231 00:12:39,692 --> 00:12:42,728 is roughly z. 232 00:12:42,728 --> 00:12:47,099 Talk about a valuable thing to learn, 233 00:12:47,099 --> 00:12:50,136 and that saves you a lot of time, by the way. 234 00:12:50,136 --> 00:12:51,971 But it's just a function and it's 235 00:12:51,971 --> 00:12:54,140 a solution to fix second long. 236 00:12:54,140 --> 00:13:00,146 So again, this is how we solve time dependent diffusion 237 00:13:00,146 --> 00:13:00,813 problems. 238 00:13:00,813 --> 00:13:03,115 And this is how you could solve this one right here. 239 00:13:03,115 --> 00:13:07,419 And what I'm going to do is I'm not going to actually solve it. 240 00:13:07,419 --> 00:13:12,291 I'm going to give you the answer to that question. 241 00:13:12,291 --> 00:13:17,263 So the time is seven hours. 242 00:13:17,263 --> 00:13:19,765 That's the answer, and I'm also going to leave you with-- 243 00:13:19,765 --> 00:13:22,034 oh, there's error function tables. 244 00:13:22,034 --> 00:13:25,037 Look at that, error function tables, 245 00:13:25,037 --> 00:13:26,639 and there's this setup of the problem. 246 00:13:26,639 --> 00:13:28,040 So I'm going to leave you actually 247 00:13:28,040 --> 00:13:29,308 with a sketch of the setup. 248 00:13:29,308 --> 00:13:33,779 And again, this isn't something we'll have on the exam, 249 00:13:33,779 --> 00:13:38,117 but I want you to have this kind of problem at your service. 250 00:13:40,753 --> 00:13:44,089 So these are all embedded in the question. 251 00:13:44,089 --> 00:13:45,591 There is your CS. 252 00:13:45,591 --> 00:13:47,893 There's your c naught. 253 00:13:47,893 --> 00:13:50,062 At this distance, this is what the question asked. 254 00:13:50,062 --> 00:13:51,897 This is the concentration we want. 255 00:13:51,897 --> 00:13:55,134 We know when we look up the diffusion of carbon, 256 00:13:55,134 --> 00:14:00,072 we assume it's not dependent on concentration, that D. 257 00:14:00,072 --> 00:14:03,008 And so we just use a constant, and then we plug it in, 258 00:14:03,008 --> 00:14:04,243 and we get a time. 259 00:14:04,243 --> 00:14:06,946 You better believe that this is really important. 260 00:14:06,946 --> 00:14:09,381 This is really, really important. 261 00:14:09,381 --> 00:14:11,250 This is how we make stuff. 262 00:14:11,250 --> 00:14:16,422 This is how we make stuff that we make our world out of. 263 00:14:16,422 --> 00:14:19,091 So that's the picture I showed you. 264 00:14:19,091 --> 00:14:28,067 And this gets me now to our last why this matters, 265 00:14:28,067 --> 00:14:31,036 and I'm doing it on the backdrop of this beautiful periodic 266 00:14:31,036 --> 00:14:31,537 table. 267 00:14:34,039 --> 00:14:41,213 So that's a lot of energy, by the way. 268 00:14:41,213 --> 00:14:42,848 First you had to make these iron pipes, 269 00:14:42,848 --> 00:14:47,186 and now you've got to case-harden them 270 00:14:47,186 --> 00:14:49,588 or maybe you've got to put even more iron in. 271 00:14:49,588 --> 00:14:53,692 Look at the other 900 C is really hot. 272 00:14:53,692 --> 00:14:57,096 How much energy do we take to make stuff as simple 273 00:14:57,096 --> 00:14:58,364 as concrete? 274 00:15:01,133 --> 00:15:02,534 It's just liquid stone. 275 00:15:02,534 --> 00:15:04,770 Didn't you just grind some stones down or something 276 00:15:04,770 --> 00:15:07,706 and then pour it out? 277 00:15:07,706 --> 00:15:10,910 Actually, if you think about concrete and other materials 278 00:15:10,910 --> 00:15:17,583 like steel, the use of them is skyrocketing. 279 00:15:17,583 --> 00:15:20,886 This is how much we're making. 280 00:15:20,886 --> 00:15:24,657 So look at this, the millions of tons. 281 00:15:24,657 --> 00:15:25,157 Let's see. 282 00:15:25,157 --> 00:15:27,760 There's steel, and there's cement. 283 00:15:27,760 --> 00:15:28,427 Look at that. 284 00:15:28,427 --> 00:15:30,162 There's the world population right there, 285 00:15:30,162 --> 00:15:36,969 and this runs out in 2009, 2010, '11, but it's continuing. 286 00:15:36,969 --> 00:15:42,841 It's continuing because it's not just that the population is 287 00:15:42,841 --> 00:15:45,744 growing, it's that the places that the population is 288 00:15:45,744 --> 00:15:49,682 growing the most are also industrializing. 289 00:15:49,682 --> 00:15:51,917 And that means building. 290 00:15:51,917 --> 00:15:54,320 You go to some of these places and there's a new building. 291 00:15:54,320 --> 00:15:59,658 Literally every block, there's a new building being built. 292 00:15:59,658 --> 00:16:02,194 That takes this stuff. 293 00:16:02,194 --> 00:16:05,264 That takes a lot of ovens at a lot 294 00:16:05,264 --> 00:16:08,534 of really high temperatures. 295 00:16:08,534 --> 00:16:15,341 Just the cement alone is accounting 296 00:16:15,341 --> 00:16:22,681 for 7% of all CO2 emissions, all CO2 emissions on the planet, 297 00:16:22,681 --> 00:16:28,220 7% of that goes into simply making this magic liquid stone, 298 00:16:28,220 --> 00:16:29,455 this powder. 299 00:16:29,455 --> 00:16:32,091 And at the core of it, what is at the core of it? 300 00:16:32,091 --> 00:16:34,326 It's chemistry. 301 00:16:34,326 --> 00:16:35,127 It's clinker. 302 00:16:35,127 --> 00:16:36,161 It's called the clinker. 303 00:16:36,161 --> 00:16:36,895 What is a clinker? 304 00:16:36,895 --> 00:16:37,930 It's this thing. 305 00:16:37,930 --> 00:16:41,467 It's simply a calcium silicate group. 306 00:16:41,467 --> 00:16:44,003 Making that is what takes all this energy. 307 00:16:44,003 --> 00:16:48,807 It takes half of it at least, making that right. 308 00:16:48,807 --> 00:16:52,411 And as always, the chemistry gives us 309 00:16:52,411 --> 00:16:58,250 the chance to get out of our constrained optimization. 310 00:16:58,250 --> 00:17:01,453 And so you've got to make this mixture of different types 311 00:17:01,453 --> 00:17:02,221 of synthetic rock. 312 00:17:02,221 --> 00:17:04,289 You've got to make mixtures of alite and belite. 313 00:17:04,289 --> 00:17:05,357 They have different names. 314 00:17:07,693 --> 00:17:11,296 And you might be able to make more belite, which 315 00:17:11,296 --> 00:17:12,263 takes less energy. 316 00:17:12,263 --> 00:17:14,633 You can cool your oven down by 300 C 317 00:17:14,633 --> 00:17:18,069 to make belite compared to alite. 318 00:17:18,069 --> 00:17:20,571 But then even though it's structurally OK, 319 00:17:20,571 --> 00:17:23,409 it takes 90 days to dry. 320 00:17:23,409 --> 00:17:24,276 So you can't do that. 321 00:17:24,276 --> 00:17:27,813 So you've got to spend the 300 extra Celsius to make 322 00:17:27,813 --> 00:17:28,947 more alite. 323 00:17:28,947 --> 00:17:33,052 Why It's in the chemistry. 324 00:17:33,052 --> 00:17:34,620 It's in the chemistry. 325 00:17:34,620 --> 00:17:38,023 And understanding, what seems like 326 00:17:38,023 --> 00:17:40,959 not a very interesting-- cement, is it really that interesting? 327 00:17:40,959 --> 00:17:43,062 You bet it is. 328 00:17:43,062 --> 00:17:49,168 7% of all CO2 emissions is just making this one material, 329 00:17:49,168 --> 00:17:51,470 and we're making a lot of it. 330 00:17:51,470 --> 00:17:52,538 We're making a lot of it. 331 00:17:52,538 --> 00:17:55,240 There's a 164 tower in Dubai that 332 00:17:55,240 --> 00:17:59,711 opened in 2010 that took a billion kilograms 333 00:17:59,711 --> 00:18:00,345 of this stuff. 334 00:18:03,715 --> 00:18:06,185 Now, this makes a lot of CO2, and I've talked about CO2 335 00:18:06,185 --> 00:18:07,820 throughout the semester. 336 00:18:07,820 --> 00:18:10,222 And so one thing I wanted to leave you with 337 00:18:10,222 --> 00:18:12,224 was also some things that we're doing about it. 338 00:18:12,224 --> 00:18:15,027 What do we do about CO2? 339 00:18:15,027 --> 00:18:19,131 So how is carbon capture and sequestration going? 340 00:18:19,131 --> 00:18:21,100 Can we take it all out? 341 00:18:21,100 --> 00:18:23,869 We put it in, can we take it out? 342 00:18:23,869 --> 00:18:26,171 And so I'll share a couple of things. 343 00:18:26,171 --> 00:18:30,809 So one of the problems with CO2 capture 344 00:18:30,809 --> 00:18:35,013 is that if you don't do it right where you make it, 345 00:18:35,013 --> 00:18:36,982 then you have to transport it, and it turns out 346 00:18:36,982 --> 00:18:39,952 that's actually really hard to transport CO2. 347 00:18:39,952 --> 00:18:41,386 And there's a lot of problems that 348 00:18:41,386 --> 00:18:42,588 have happened over the years. 349 00:18:42,588 --> 00:18:44,189 In the '80s, there was a leak that 350 00:18:44,189 --> 00:18:46,291 killed thousands of people. 351 00:18:46,291 --> 00:18:49,394 There have been massive leaks in Canada 352 00:18:49,394 --> 00:18:51,630 in transporting this material. 353 00:18:51,630 --> 00:18:55,100 So transporting is actually really hard to do. 354 00:18:55,100 --> 00:18:56,335 There's metal pipe corrosion. 355 00:18:56,335 --> 00:19:00,506 This is a great chemistry problem unsolved. 356 00:19:00,506 --> 00:19:03,909 And then the next part of CO2 sequestration 357 00:19:03,909 --> 00:19:05,944 is one is transporting it that's challenging, 358 00:19:05,944 --> 00:19:07,146 and the other is storing it. 359 00:19:07,146 --> 00:19:08,514 What do you do with it? 360 00:19:08,514 --> 00:19:11,049 Let's suppose we could capture it. 361 00:19:11,049 --> 00:19:12,217 Well, then what? 362 00:19:12,217 --> 00:19:14,853 And there's ideas around this. 363 00:19:14,853 --> 00:19:18,891 So you could pump it maybe underground, geosequestration. 364 00:19:18,891 --> 00:19:21,627 That's not a sure thing. 365 00:19:21,627 --> 00:19:23,795 We don't know, we don't understand 366 00:19:23,795 --> 00:19:26,965 at those scales exactly how well we can in case this material 367 00:19:26,965 --> 00:19:29,735 and how long it lasts, so a lot of questions with that. 368 00:19:29,735 --> 00:19:33,138 There's a whole line of thinking on putting it in the ocean. 369 00:19:36,008 --> 00:19:36,775 Right? 370 00:19:36,775 --> 00:19:38,744 Really? 371 00:19:38,744 --> 00:19:43,549 So you want to fix the CO2 problem by acidifying 372 00:19:43,549 --> 00:19:45,884 the oceans even faster? 373 00:19:45,884 --> 00:19:47,019 OK. 374 00:19:47,019 --> 00:19:50,022 Interesting. 375 00:19:50,022 --> 00:19:53,358 So transport and sequestration is a big problem, 376 00:19:53,358 --> 00:19:56,595 but what about technologies where you simply sequester it 377 00:19:56,595 --> 00:20:00,933 right there where you make it, like clean coal. 378 00:20:00,933 --> 00:20:03,835 You may have heard of clean coal, so clean coal. 379 00:20:03,835 --> 00:20:06,004 So I'm going to look at a case study of a clean coal 380 00:20:06,004 --> 00:20:07,573 project in the US. 381 00:20:07,573 --> 00:20:11,143 In 2005, I got really excited because eight companies joined, 382 00:20:11,143 --> 00:20:13,679 and it was called Future Gen, and the US government was going 383 00:20:13,679 --> 00:20:15,280 to put a lot of money into it. 384 00:20:15,280 --> 00:20:17,449 They were going to capture 90% of the CO2. 385 00:20:17,449 --> 00:20:19,451 You get a little bit less efficiency. 386 00:20:19,451 --> 00:20:20,953 Depending on how you think about it, 387 00:20:20,953 --> 00:20:23,522 it could be 30% less efficiency, I mean, less power 388 00:20:23,522 --> 00:20:26,892 out of the plant, but you sequester the CO2. 389 00:20:26,892 --> 00:20:30,095 And in 2009, construction was planned in Illinois. 390 00:20:30,095 --> 00:20:31,597 In 2010, it was canceled. 391 00:20:31,597 --> 00:20:33,832 In 2010, it was restarted. 392 00:20:33,832 --> 00:20:39,004 In 2012, there was all sorts of discussions with the DOE 393 00:20:39,004 --> 00:20:42,107 that agreed to pay $1.1 billion. 394 00:20:42,107 --> 00:20:44,643 It was all located, and then the companies dropped out 395 00:20:44,643 --> 00:20:45,911 and the DOE canceled projects. 396 00:20:45,911 --> 00:20:47,312 So that was 10 years. 397 00:20:47,312 --> 00:20:51,250 10 years and $200 million of taxpayer dollars and absolutely 398 00:20:51,250 --> 00:20:53,418 nothing has come out of it. 399 00:20:53,418 --> 00:20:58,523 So one of the things I want to point out about this direction, 400 00:20:58,523 --> 00:21:00,792 I'm not saying that it's not a good direction 401 00:21:00,792 --> 00:21:03,161 to keep pursuing. 402 00:21:03,161 --> 00:21:05,864 But the timescales are long. 403 00:21:05,864 --> 00:21:08,233 So we need to be able to make decisions that 404 00:21:08,233 --> 00:21:10,135 can cover longer timescales. 405 00:21:10,135 --> 00:21:12,638 That's a huge part of the challenge with this. 406 00:21:12,638 --> 00:21:15,274 It's a policy challenge as much as it is a technical one. 407 00:21:18,277 --> 00:21:22,748 And tying this back to the cement, 408 00:21:22,748 --> 00:21:25,951 there is some really interesting research 409 00:21:25,951 --> 00:21:28,654 that's going on in actually instead of-- 410 00:21:28,654 --> 00:21:29,888 OK, so you've got the CO2. 411 00:21:29,888 --> 00:21:31,857 It comes out when you make it because the ovens 412 00:21:31,857 --> 00:21:34,826 and you're burning stuff, but what if you could take that CO2 413 00:21:34,826 --> 00:21:37,796 and just put it into the thing you're making. 414 00:21:37,796 --> 00:21:39,931 And by the way, if what you're making 415 00:21:39,931 --> 00:21:43,268 is a huge scale like cement, then maybe you 416 00:21:43,268 --> 00:21:45,370 can put a lot of it in, and maybe that 417 00:21:45,370 --> 00:21:47,105 could have a real global impact. 418 00:21:47,105 --> 00:21:52,044 So there's a lot of interest in substantial global carbon 419 00:21:52,044 --> 00:21:54,079 uptake by cement carbonation. 420 00:21:54,079 --> 00:21:56,081 So maybe you could get some of it in the cement. 421 00:21:56,081 --> 00:21:57,249 I like this paper. 422 00:21:57,249 --> 00:21:59,318 I'm pointing it out because they say that they 423 00:21:59,318 --> 00:22:01,753 used Fick's diffusion law. 424 00:22:01,753 --> 00:22:04,323 They modeled the carbon uptake by applying Fick's diffusion 425 00:22:04,323 --> 00:22:04,823 law. 426 00:22:04,823 --> 00:22:06,058 Yeah. 427 00:22:06,058 --> 00:22:06,892 It actually matters. 428 00:22:09,428 --> 00:22:11,463 Right? 429 00:22:11,463 --> 00:22:13,465 You can do this too now. 430 00:22:13,465 --> 00:22:16,935 And just a few weeks ago on CNN, this concrete, yes, 431 00:22:16,935 --> 00:22:18,904 concrete is going high tech. 432 00:22:18,904 --> 00:22:19,571 Why? 433 00:22:19,571 --> 00:22:22,507 Because this company has managed to figure out 434 00:22:22,507 --> 00:22:25,410 how to put a bunch of CO2 into the concrete while 435 00:22:25,410 --> 00:22:28,213 they make it, and it doesn't change the mechanical integrity 436 00:22:28,213 --> 00:22:29,548 of the concrete. 437 00:22:29,548 --> 00:22:30,649 And it's in there. 438 00:22:30,649 --> 00:22:32,651 It's actually in there. 439 00:22:32,651 --> 00:22:34,486 This is all chemistry. 440 00:22:34,486 --> 00:22:35,387 This is all chemistry. 441 00:22:35,387 --> 00:22:38,690 So this is, I think, another very interesting direction 442 00:22:38,690 --> 00:22:41,993 where technology can play a vital role 443 00:22:41,993 --> 00:22:44,896 in this particular global challenge. 444 00:22:46,264 --> 00:22:52,003 And now I'm putting the chalk down, 445 00:22:52,003 --> 00:22:54,206 and I come to the conclusion I can't look there. 446 00:22:54,206 --> 00:22:55,440 I'm going to get sad. 447 00:22:55,440 --> 00:23:01,012 You're making me-- the first thing about this 448 00:23:01,012 --> 00:23:07,786 that I got to do is I got to thank people. 449 00:23:07,786 --> 00:23:12,858 First I got to thank the concepts, 450 00:23:12,858 --> 00:23:15,360 got to thank the material. 451 00:23:15,360 --> 00:23:18,530 This is what we have talked about all semester. 452 00:23:18,530 --> 00:23:21,299 This is what we have learned. 453 00:23:21,299 --> 00:23:27,105 This is underneath the hood of so much, 454 00:23:27,105 --> 00:23:30,041 and I hope that I've conveyed that to you. 455 00:23:30,041 --> 00:23:34,246 This is a starting point for so much. 456 00:23:34,246 --> 00:23:35,113 What have we learned? 457 00:23:35,113 --> 00:23:36,848 Well, we've learned how to go back and forth. 458 00:23:36,848 --> 00:23:38,316 This is what I showed you on day one. 459 00:23:38,316 --> 00:23:39,418 And now what have we done? 460 00:23:39,418 --> 00:23:40,419 We have filled this out. 461 00:23:40,419 --> 00:23:42,821 We filled it out with balancing reactions. 462 00:23:42,821 --> 00:23:45,657 We filled it out with the periodic table, that one. 463 00:23:45,657 --> 00:23:48,427 We filled it out with electrons, Bohr model, Schrodinger, 464 00:23:48,427 --> 00:23:50,962 atomic orbitals, molecular orbitals, ionic solids, 465 00:23:50,962 --> 00:23:53,698 Lewis dots, VSEPR, Van der Waals, London, H-bonds, 466 00:23:53,698 --> 00:23:55,567 all sorts of inner intermolecular forces, 467 00:23:55,567 --> 00:23:58,303 metallic bonds, semiconductors, bands, crystals, symmetry, 468 00:23:58,303 --> 00:24:01,039 lattices, planes, x-rays, x-ray diffraction, defects, 469 00:24:01,039 --> 00:24:04,309 amorphous glassy materials, reaction rates, rate laws, 470 00:24:04,309 --> 00:24:07,813 diffusion, solubility, Arrhenius, acids and bases, 471 00:24:07,813 --> 00:24:09,681 polymers, and their properties. 472 00:24:16,054 --> 00:24:17,055 That's you guys. 473 00:24:22,260 --> 00:24:24,796 That's you guys that have learned that material. 474 00:24:28,433 --> 00:24:30,402 It blows me away. 475 00:24:30,402 --> 00:24:32,637 That's a lot of stuff, and we've learned it all, 476 00:24:32,637 --> 00:24:37,209 and we've integrated it into our lives. 477 00:24:37,209 --> 00:24:38,977 But you couldn't have learned any of this, 478 00:24:38,977 --> 00:24:43,448 we couldn't have done any of this without some people. 479 00:24:43,448 --> 00:24:44,983 So now we thank the subjects. 480 00:24:44,983 --> 00:24:46,117 We thank the people. 481 00:24:46,117 --> 00:24:47,853 Laura, would you stand up please? 482 00:24:55,026 --> 00:24:55,527 Yeah. 483 00:25:04,436 --> 00:25:06,104 Many of you have interacted with Laura, 484 00:25:06,104 --> 00:25:08,907 and you know and now sometimes you might get a short answer. 485 00:25:08,907 --> 00:25:12,410 You might get a not a short answer. 486 00:25:12,410 --> 00:25:13,712 But why is that? 487 00:25:13,712 --> 00:25:18,650 It's because Laura cares deeply, deeply about you all 488 00:25:18,650 --> 00:25:21,887 and about your learning and your experience in this class 489 00:25:21,887 --> 00:25:22,687 and at MIT. 490 00:25:22,687 --> 00:25:23,855 She cares deeply. 491 00:25:23,855 --> 00:25:25,257 And that's the kind of thing that 492 00:25:25,257 --> 00:25:26,525 makes this class what it is. 493 00:25:26,525 --> 00:25:29,928 We wouldn't have any shot at it without Laura. 494 00:25:29,928 --> 00:25:32,764 So Laura, thank you very much. 495 00:25:32,764 --> 00:25:35,000 It's sort of like when you drop your kids off, 496 00:25:35,000 --> 00:25:38,403 if they go to sleep-away camp, there's like the camp parent 497 00:25:38,403 --> 00:25:39,804 who makes sure that your kids-- 498 00:25:39,804 --> 00:25:43,008 it's like they make sure that your kids will 499 00:25:43,008 --> 00:25:47,312 brush their teeth, get to bed, have a blanket. 500 00:25:47,312 --> 00:25:50,749 And they check in on your kids all the time. 501 00:25:50,749 --> 00:25:55,554 And I feel like we have that for this class. 502 00:25:55,554 --> 00:25:56,888 It's Laura. 503 00:25:56,888 --> 00:25:58,023 So thank you, Laura. 504 00:25:58,023 --> 00:26:01,092 But now the thing is now the other, now, 505 00:26:01,092 --> 00:26:03,161 I introduce these people to you. 506 00:26:03,161 --> 00:26:04,896 Isaac, I still don't have your picture. 507 00:26:04,896 --> 00:26:09,100 But can the TAs please stand up? 508 00:26:09,100 --> 00:26:10,001 Can the TAs stand up? 509 00:26:10,001 --> 00:26:10,502 Come on. 510 00:26:17,409 --> 00:26:18,410 Thank you. 511 00:26:25,350 --> 00:26:26,818 Thank you. 512 00:26:26,818 --> 00:26:30,288 Thank you. 513 00:26:30,288 --> 00:26:36,161 I am so incredibly lucky to have this quality 514 00:26:36,161 --> 00:26:40,699 people, this quality of staff, these kind, caring, 515 00:26:40,699 --> 00:26:45,337 passionate, amazing people as our TAs for this class. 516 00:26:45,337 --> 00:26:50,342 And I am so lucky I get to meet with them every week 517 00:26:50,342 --> 00:26:53,845 to talk about you guys-- 518 00:26:53,845 --> 00:26:55,680 it's always good; don't worry. 519 00:26:55,680 --> 00:26:59,951 it's always good-- and interact even much more than that 520 00:26:59,951 --> 00:27:01,987 about education, about teaching, about how 521 00:27:01,987 --> 00:27:07,592 to make this a fantastic experience for all of you. 522 00:27:07,592 --> 00:27:09,160 So thanks to the TAs. 523 00:27:09,160 --> 00:27:13,999 And that's why I want the TAs to throw the T-shirts out, 524 00:27:13,999 --> 00:27:17,235 and we'll do that in a minute, well, a couple minutes. 525 00:27:17,235 --> 00:27:18,036 No. 526 00:27:18,036 --> 00:27:20,872 One? 527 00:27:20,872 --> 00:27:24,609 But see, it's the TAs that have been here for you, 528 00:27:24,609 --> 00:27:26,011 but it's also you all. 529 00:27:26,011 --> 00:27:26,778 There is you. 530 00:27:30,315 --> 00:27:33,985 It's you all that have been here for each other. 531 00:27:33,985 --> 00:27:37,188 And so I see it because I talked to some of you. 532 00:27:37,188 --> 00:27:41,159 I don't talk to all of you, but I see the community that forms, 533 00:27:41,159 --> 00:27:42,861 and I am very appreciative of that, 534 00:27:42,861 --> 00:27:44,696 and I'd like you to be appreciative of that. 535 00:27:44,696 --> 00:27:47,365 So let's thank each other here for just a minute. 536 00:27:47,365 --> 00:27:55,807 It's really pretty-- this is actually getting me revved up 537 00:27:55,807 --> 00:27:57,742 a little bit. 538 00:27:57,742 --> 00:27:59,511 Now, I skipped over. 539 00:27:59,511 --> 00:28:01,646 The goodie bags are amazing, and so I'm 540 00:28:01,646 --> 00:28:05,350 thankful to the goodie bags and to the department, if anyone 541 00:28:05,350 --> 00:28:07,519 is here from the department, for helping us support 542 00:28:07,519 --> 00:28:11,056 these goodie bags, thank you. 543 00:28:11,056 --> 00:28:12,557 Thank you. 544 00:28:12,557 --> 00:28:13,725 Yeah, thank you. 545 00:28:13,725 --> 00:28:14,693 That's good. 546 00:28:18,163 --> 00:28:20,699 So I'm very grateful to that. 547 00:28:20,699 --> 00:28:22,033 I'm grateful to all of you. 548 00:28:22,033 --> 00:28:28,406 And last but not least, I guess just last, 549 00:28:28,406 --> 00:28:30,542 I am thankful to Harvard. 550 00:28:30,542 --> 00:28:31,943 I was going to say something else. 551 00:28:31,943 --> 00:28:38,116 But anyway, I'm thankful to all of these resources 552 00:28:38,116 --> 00:28:39,184 that we have used. 553 00:28:42,520 --> 00:28:49,828 And so I'm going to give you some closing comments. 554 00:28:49,828 --> 00:28:54,499 I started this semester off in the first lecture, 555 00:28:54,499 --> 00:28:56,568 and I asked you all a question. 556 00:28:56,568 --> 00:28:59,170 And the question was, why are you here? 557 00:28:59,170 --> 00:29:03,541 And I said really, really, really, why are you here. 558 00:29:03,541 --> 00:29:05,343 Why did you come to MIT? 559 00:29:05,343 --> 00:29:08,780 And I asked you, did you come here 560 00:29:08,780 --> 00:29:12,550 so you can just phone it in, get a stamp in four years, 561 00:29:12,550 --> 00:29:14,452 and go out? 562 00:29:14,452 --> 00:29:16,821 Did you come here so you can walk around 563 00:29:16,821 --> 00:29:20,091 some place in privilege and look down on other people? 564 00:29:20,091 --> 00:29:22,260 That is not why you're here. 565 00:29:22,260 --> 00:29:25,296 That is not why you came to MIT. 566 00:29:25,296 --> 00:29:29,300 You came to MIT because you know that this 567 00:29:29,300 --> 00:29:32,937 is where we will make the transition from being 568 00:29:32,937 --> 00:29:36,207 able to answer any question to knowing which question to ask. 569 00:29:36,207 --> 00:29:38,810 That's the transition from student to scholar. 570 00:29:38,810 --> 00:29:44,215 And you know that you came here because you have a passion, 571 00:29:44,215 --> 00:29:47,252 and you want to come to a place where you can take that passion 572 00:29:47,252 --> 00:29:50,255 and you can try to solve really hard problems together 573 00:29:50,255 --> 00:29:51,623 to make the world a better place. 574 00:29:51,623 --> 00:29:53,324 Those are reasons why you came here. 575 00:29:53,324 --> 00:29:58,163 You came here because you know that progress does not 576 00:29:58,163 --> 00:30:00,765 happen because of success. 577 00:30:00,765 --> 00:30:01,699 It doesn't. 578 00:30:01,699 --> 00:30:03,334 It happens entirely because of what 579 00:30:03,334 --> 00:30:05,603 you choose to do with failure. 580 00:30:05,603 --> 00:30:10,942 That's MIT, that's the MIT way, and that's why you're here, 581 00:30:10,942 --> 00:30:15,146 and I asked you to think about that on the first lecture. 582 00:30:15,146 --> 00:30:18,249 And then I gave you a whole lot of examples 583 00:30:18,249 --> 00:30:19,117 throughout the class. 584 00:30:19,117 --> 00:30:21,186 I tried to connect our learning and solid state 585 00:30:21,186 --> 00:30:24,889 chemistry to global challenges, to global challenges 586 00:30:24,889 --> 00:30:27,192 that we face. 587 00:30:27,192 --> 00:30:29,260 And I tried to do that. 588 00:30:29,260 --> 00:30:30,962 So I had 36 opportunities. 589 00:30:30,962 --> 00:30:33,031 There's many more, so I had to pick and choose 590 00:30:33,031 --> 00:30:36,801 carefully to try to give you a sense of some of these things. 591 00:30:39,337 --> 00:30:42,106 And the thing is about these challenges, one I just 592 00:30:42,106 --> 00:30:47,145 talked about in many others, it's not that these are things 593 00:30:47,145 --> 00:30:51,249 that we need to do soon. 594 00:30:51,249 --> 00:30:55,253 There is an urgency of now about these things. 595 00:30:55,253 --> 00:30:56,955 There is an urgency of now. 596 00:30:56,955 --> 00:31:01,926 There's no more time to talk about it. 597 00:31:01,926 --> 00:31:05,930 And so these challenges, it's not like something happens over 598 00:31:05,930 --> 00:31:09,634 here, happens over there. 599 00:31:09,634 --> 00:31:11,769 These are planetary challenges. 600 00:31:11,769 --> 00:31:13,438 These cover the whole thing. 601 00:31:13,438 --> 00:31:18,276 So it's all on the table. 602 00:31:18,276 --> 00:31:21,279 It's all on the line. 603 00:31:21,279 --> 00:31:23,214 And by the way, if it's a planetary challenge, 604 00:31:23,214 --> 00:31:25,250 it means the challenge doesn't care 605 00:31:25,250 --> 00:31:27,952 if you're in a blue State or a red State 606 00:31:27,952 --> 00:31:31,055 or if you live in Europe or Africa or here. 607 00:31:31,055 --> 00:31:32,790 It doesn't care. 608 00:31:32,790 --> 00:31:35,927 So we better figure out how to get our act together and work 609 00:31:35,927 --> 00:31:39,063 together to solve these very hard problems. 610 00:31:39,063 --> 00:31:41,266 And that's why you're here. 611 00:31:41,266 --> 00:31:43,635 That's why you're here. 612 00:31:43,635 --> 00:31:45,503 And so on the first lecture, I asked 613 00:31:45,503 --> 00:31:46,938 you to think about why you're here, 614 00:31:46,938 --> 00:31:49,374 and on this very last lecture, I'm 615 00:31:49,374 --> 00:31:53,411 asking you to think about what you want to do about that. 616 00:31:53,411 --> 00:31:56,381 What do you want to do about that? 617 00:31:56,381 --> 00:31:59,684 And there's a lot of things you can do. 618 00:31:59,684 --> 00:32:03,922 I don't mean that you have to work on one of these things 619 00:32:03,922 --> 00:32:05,290 we've talked about in this class. 620 00:32:05,290 --> 00:32:06,257 That's not what I mean. 621 00:32:06,257 --> 00:32:08,760 I mean, think about what it is that you really want to do 622 00:32:08,760 --> 00:32:11,663 and how you want to do it, and then go for it. 623 00:32:14,265 --> 00:32:16,968 You might have figured that out before you came here. 624 00:32:16,968 --> 00:32:19,604 You may know-- gesundheit-- 625 00:32:19,604 --> 00:32:21,306 already way before you got here. 626 00:32:21,306 --> 00:32:24,075 You may be figuring it out right now. 627 00:32:24,075 --> 00:32:29,047 You may have no clue what you want to do when you graduate. 628 00:32:29,047 --> 00:32:31,382 All of those are fine. 629 00:32:31,382 --> 00:32:33,618 All of those are fine. 630 00:32:33,618 --> 00:32:36,020 But what I want to leave you with 631 00:32:36,020 --> 00:32:39,891 is a framework and some thinking that what can I 632 00:32:39,891 --> 00:32:42,860 leave you with as a suggestion, as a framework. 633 00:32:42,860 --> 00:32:45,663 And it really comes down to three ingredients, 634 00:32:45,663 --> 00:32:47,165 three ingredients that I'm asking 635 00:32:47,165 --> 00:32:49,400 you to think about when you go off 636 00:32:49,400 --> 00:32:52,704 and do, when you leave here, when you go off and do. 637 00:32:52,704 --> 00:32:53,738 What are you going to do? 638 00:32:53,738 --> 00:32:55,239 How are you going to frame this? 639 00:32:55,239 --> 00:32:59,444 And so the first ingredient is kindness. 640 00:32:59,444 --> 00:33:00,611 Now OK. 641 00:33:00,611 --> 00:33:01,779 Bear with me. 642 00:33:01,779 --> 00:33:04,882 Because you're all thinking, what is he talking about? 643 00:33:04,882 --> 00:33:08,252 This is a chemistry class, and you're talking about kindness. 644 00:33:12,323 --> 00:33:15,259 But you see, the thing is, I'm trying 645 00:33:15,259 --> 00:33:18,730 to think about what is a framework that if you follow it 646 00:33:18,730 --> 00:33:20,965 you will do good. 647 00:33:20,965 --> 00:33:24,002 You will help change this world for the better, which 648 00:33:24,002 --> 00:33:25,636 is what we do at MIT. 649 00:33:25,636 --> 00:33:27,338 It's how we think. 650 00:33:27,338 --> 00:33:29,540 And the thing is I don't care if you define kindness 651 00:33:29,540 --> 00:33:36,614 as love or as helping someone or as community or as 652 00:33:36,614 --> 00:33:39,183 on one of those dates when the candle was in the room 653 00:33:39,183 --> 00:33:42,086 and you did the calculation and you saved the day 654 00:33:42,086 --> 00:33:43,955 because you knew oxygen was going to run out. 655 00:33:43,955 --> 00:33:45,423 That's all kindness. 656 00:33:45,423 --> 00:33:46,424 All of that is kindness. 657 00:33:46,424 --> 00:33:49,894 But the thing is that if you have kindness in what you do, 658 00:33:49,894 --> 00:33:51,362 it's really hard to do bad. 659 00:33:54,532 --> 00:33:56,567 Is that under the hood? 660 00:33:56,567 --> 00:33:58,069 Is there an element of kindness? 661 00:33:58,069 --> 00:33:59,937 You can't have too much of it. 662 00:33:59,937 --> 00:34:02,340 We need that vector. 663 00:34:02,340 --> 00:34:05,543 We need that vector in this world. 664 00:34:05,543 --> 00:34:07,678 So that's one ingredient, and the second ingredient 665 00:34:07,678 --> 00:34:08,212 is knowledge. 666 00:34:08,212 --> 00:34:11,315 Now, what I mean by this is acquisition of knowledge. 667 00:34:11,315 --> 00:34:13,384 And we have done a lot of that here in this class, 668 00:34:13,384 --> 00:34:15,152 and you do a lot of that at MIT, and we 669 00:34:15,152 --> 00:34:18,156 celebrate these acquisitions. 670 00:34:18,156 --> 00:34:20,291 What I'm asking you to do is think about this 671 00:34:20,291 --> 00:34:21,592 as you go forward. 672 00:34:21,592 --> 00:34:23,828 How are you acquiring knowledge? 673 00:34:23,828 --> 00:34:25,530 How are you learning? 674 00:34:25,530 --> 00:34:26,397 That sounds cliche. 675 00:34:26,397 --> 00:34:28,232 Always learn. 676 00:34:28,232 --> 00:34:30,034 You guys have to keep doing that. 677 00:34:30,034 --> 00:34:32,136 You have to keep doing that because, for you, it's 678 00:34:32,136 --> 00:34:36,274 nourishment, and it's another one of these vectors. 679 00:34:36,274 --> 00:34:38,810 You can't do any harm by learning. 680 00:34:38,810 --> 00:34:42,580 You can only do good for yourself and for everyone 681 00:34:42,580 --> 00:34:44,315 that you care about. 682 00:34:44,315 --> 00:34:47,351 So keep doing it. 683 00:34:47,351 --> 00:34:49,387 The rate might change of learning acquisition 684 00:34:49,387 --> 00:34:52,690 as a reaction, the rate constant might be lower. 685 00:34:52,690 --> 00:34:56,327 We know places where that's already the case. 686 00:34:56,327 --> 00:35:00,898 And that's OK. 687 00:35:00,898 --> 00:35:04,502 Maybe the order is lower too down there, 688 00:35:04,502 --> 00:35:07,605 but I think they probably are learning something. 689 00:35:10,508 --> 00:35:12,710 Keep that going. 690 00:35:12,710 --> 00:35:14,078 And the last thing is passion. 691 00:35:14,078 --> 00:35:17,915 And this involves your talents. 692 00:35:17,915 --> 00:35:20,585 You all have talents already. 693 00:35:20,585 --> 00:35:23,521 You all have them because that's part of who you are 694 00:35:23,521 --> 00:35:25,957 and why you're here. 695 00:35:25,957 --> 00:35:30,061 Those are things that you bring a passion to. 696 00:35:30,061 --> 00:35:32,096 What are those talents? 697 00:35:32,096 --> 00:35:34,866 Maybe some of them are hidden, but work on them 698 00:35:34,866 --> 00:35:35,933 and pursue them. 699 00:35:35,933 --> 00:35:37,835 Do things that you literally are so 700 00:35:37,835 --> 00:35:39,570 excited about you can't sleep sometimes 701 00:35:39,570 --> 00:35:41,706 because of the excitement. 702 00:35:41,706 --> 00:35:43,674 That's what I'm talking about. 703 00:35:43,674 --> 00:35:45,343 Follow that. 704 00:35:45,343 --> 00:35:48,179 Feed it. 705 00:35:48,179 --> 00:35:54,051 And while you do, lose the fear. 706 00:35:54,051 --> 00:35:57,121 Avoid greed, and embrace challenge. 707 00:35:57,121 --> 00:35:59,557 That's what MT is. 708 00:35:59,557 --> 00:36:01,792 That's why we're here. 709 00:36:01,792 --> 00:36:04,428 That's why we're here. 710 00:36:04,428 --> 00:36:06,063 So I feel like these three ingredients, 711 00:36:06,063 --> 00:36:08,399 I've thought about this, and I thought about these three 712 00:36:08,399 --> 00:36:10,001 ingredients, and I've thought about-- 713 00:36:10,001 --> 00:36:11,869 we have these already. 714 00:36:11,869 --> 00:36:17,108 You all have these ingredients because that is also MIT, 715 00:36:17,108 --> 00:36:20,344 and you are here, and you are MIT. 716 00:36:20,344 --> 00:36:23,915 And so what I'm asking you to do is to hold onto them 717 00:36:23,915 --> 00:36:25,149 and keep thinking about them. 718 00:36:27,652 --> 00:36:32,056 There's a lot of reasons why I love to teach, 719 00:36:32,056 --> 00:36:35,927 but one of the big ones is when I think about the challenges 720 00:36:35,927 --> 00:36:38,829 that I share with you guys and I have 721 00:36:38,829 --> 00:36:41,365 36 chances to look up in the room 722 00:36:41,365 --> 00:36:42,767 and I think about those challenges 723 00:36:42,767 --> 00:36:44,235 and I think about these ingredients 724 00:36:44,235 --> 00:36:46,904 and I think about all of you, I actually 725 00:36:46,904 --> 00:36:49,106 feel like we have a shot. 726 00:36:49,106 --> 00:36:50,708 I actually feel that. 727 00:36:50,708 --> 00:36:56,414 And so with that, good luck on the final, 728 00:36:56,414 --> 00:36:57,615 and have a fantastic break. 729 00:36:59,717 --> 00:37:01,219 Thank you so much. 730 00:37:01,219 --> 00:37:02,220 Thank you. 731 00:37:02,220 --> 00:37:03,688 Thank you, guys. 732 00:37:03,688 --> 00:37:05,156 Thank you, guys. 733 00:37:05,156 --> 00:37:06,157 Thank you. 734 00:37:06,157 --> 00:37:07,158 Thank you. 735 00:37:07,158 --> 00:37:09,126 Thank you so much. 736 00:37:09,126 --> 00:37:10,094 Thank you. 737 00:37:13,431 --> 00:37:14,332 You guys are amazing. 738 00:37:17,501 --> 00:37:18,502 Thank you. 739 00:37:18,502 --> 00:37:19,470 Thank you. 740 00:37:26,844 --> 00:37:29,280 Thank you all so much. 741 00:37:29,280 --> 00:37:30,915 I'm going to have to leave here, or I'm 742 00:37:30,915 --> 00:37:33,417 going to get really emotional. 743 00:37:33,417 --> 00:37:35,253 I've clearly got a lot of other dance moves 744 00:37:35,253 --> 00:37:39,890 the TAs have helped me, so I can practice those. 745 00:37:39,890 --> 00:37:41,425 Thank you so much. 746 00:37:41,425 --> 00:37:42,994 That's just incredible. 747 00:37:42,994 --> 00:37:45,596 You guys are all incredible, and this has been incredible. 748 00:37:45,596 --> 00:37:50,034 So we do have 10 minutes. 749 00:37:50,034 --> 00:37:50,901 I'm going to leave. 750 00:37:50,901 --> 00:37:53,204 So you guys can fill evaluations out 751 00:37:53,204 --> 00:37:55,940 without me being in the room. 752 00:37:55,940 --> 00:37:58,576 And so you can say whatever you want. 753 00:37:58,576 --> 00:38:01,612 Again, don't let the free T-shirts being thrown at you 754 00:38:01,612 --> 00:38:06,617 influence your opinion or the free candy. 755 00:38:06,617 --> 00:38:12,623 But thanks, everyone, for a fantastic semester. 756 00:38:12,623 --> 00:38:14,325 Thank you. 757 00:38:14,325 --> 00:38:14,825 Thanks. 758 00:38:17,762 --> 00:38:19,096 That was amazing, you guys.