Science & Technology Q&A for Kids (and others) [Part 126]

foreign welcome to another episode of Science and Technology q a for kids and others and I see all kinds of questions saved up here so let me uh dig into them so we have one from RBS if you ask an AI the exact same question several times will it give the same answer or will it change based on some random function so well the different kinds of things people have called AI over the years that people have talked about artificial intelligence which kind of dates back into the mid-1950s but the most recent kind of popular version of AI and things like chat GPT those are so-called large language models are llms and let me answer for that case so the what Chachi PT is doing in all cases is you've given it some textual prompt you've given it a certain amount of text and its goal is to keep filling in more text you say uh you know give an essay about such and such and it will then start writing the essay that it thinks would have been found on some document on the web or something where it's said at the top you know here's write an essay about this and then there's the result from the essay so it's always trying to complete the text that you kind of started it from and uh question is well how does I let's not talk in detail about how it does it but essentially what's happening is that it has been trained once from the content of the web and books and so on maybe a trillion words of text it's been kind of trained on the way humans typically create text and its goal is to complete text to give it using the way humans typically write text but what it actually computes through its neural net it has all these things that represent the neural net is is is based on kind of computing values of uh things it has just a whole lot of numbers it turns all the words you give at the input it turns into numbers numerical representations and the output it will produce is a giant list of the probabilities for essentially all possible words in English actually all possible sub word tokens in general sometimes they're complete words like the sometimes they're just pieces of words for longer words but so its output is the probabilities for essentially all possible words and then the question is well what that that's its output at each step as it it tries to complete your text and in each step it's trying to add one more word to the text it's produced and so what it knows is what's the probability for that word it adds to be any of the possible words in English okay so then the final question is okay you know the probabilities for all the possible words in English which one should you pick so for example there will be one word that is the most probable word to come next and there'll be the sort of second most probable word and so on down to the you know fifty thousandth most probable word okay so the way these models are set up usually there is a parameter called the temperature which is used to kind of decide whether you pick the most probable word or sometimes pick the less than most probable word if you use zero temperature the way the model is defined is it will always pick the most probable word at every step and actually what tends to happen is if you do that the essays you get tend to be kind of flat that was particularly true you know chat gbt is based on the GPT generative pre-training neural net version 3.5 from open AI um and uh in in its case if you set it to have zero temperature it will produce this text that's sort of okay but it's a bit monotonous if you go back to gpd3 in an earlier version and you set it to zero temperature it will often get so monotonous that it's like exactly repeating words and exactly repeating sentences and it just sometimes gets into a loop and just keeps saying the same thing over and over again with gpt4 even at zero temperature does a bit better it um it's a bigger neural net with more probabilities and and so on in it um it uh it doesn't tend to get quite as monotonous but so the at zero temperature the neural net will always produce the same results given a prompt given a certain input it will always generate the succession of words that come next will always be the same in the typical way these things are set up as soon as you're at non-zero temperature that won't be the case because at as I said zero temperature the okay working out what the probabilities of all possible words are that's just determined by having all these numbers flow through the neural net then the question is well which word do you actually pick well that's something that involves deciding uh the sort of determining from probabilities what you're going to pick zero temperature you always pick the most probable word it'll always be the same most probable word every time you run the neural net and you'll get the same thing every time you run the run the network and um the the thing that um um in if you are operating at non-zero temperature you don't always pick the most probable word with some probability you pick a less than most probable word as you increase the temperature the the range of less probable words that you that you sample gets bigger it's it's it's roughly mathematically it's determined by an exponential the probability goes down exponentially as you go further into the list of words so I think the the typical chat gbt models have a maximum temperature of two and at a maximum temperature of two you're going down into the not so probable words you know you're going you might be picking the 20th most probable word sometimes or the tenth most probable word or whatever if you do that you get much Wilder text as a matter of fact for I was literally just doing that testing out some new technology that we'll be announcing the next few days um that uh uh relates to this and at temperature two um I think even GPT 4 is producing wild stuff I mean it's just writing weird things where it's just like dropping in weird weird random words in different places and so on it's very creative but it's also very disorganized and so on so zero temperature sometimes maybe for writing like woven language code or programming language code or whatever zero temperature may be a good thing to pick one of the things that was done for chat gbt was people played around with well what's the best temperature to pick and a temperature of 0.8 turned out to be the one that seemed to give essays and so on that were neither too boring nor too wild now is there a sense in which that temperature corresponds with anything like physical temperature with molecules bouncing around no it's just a mathematical coincidence and one the fact that one used an exponential distribution like the distribution of probabilities to find molecules with certain energies is really coincidental and is just a feature of the fact that uh as sort of a certain knowledge of statistical physics which makes one kind of immediately start thinking of those kinds of distributions when one's thinking about these these sorts of probabilities now in general uh that's what happens if you have a particular neural net trained in a particular way if you retrain the neural nets all bets are off because the training of a neural Nets also involves all kinds of probabilities figuring out which weights to use in in uh between neurons and so on that's absolutely and the usual way training is done that's it's full of probabilistic it's full of things that are just picked probabilistically in doing that so if you retrain the neural net you'll it will definitely do different things it's kind of like for a human if you if you kind of relearn Things No Doubt the ways those things will be encoded in your brain are different you know I have to tell a story I was just a few weeks ago I happened to see a chap I've I've known off and on for ages of philosopher named David Chalmers who writes about computation and its philosophical features and about topics like free will the question of whether what we do is somehow determined by underlying rules or whether what we do is somehow something that is freely determined under our own agency so to speak and was having this conversation and uh because he works on Free Will and I've also uh written about Free Will and uh how one can end up through computational irreducibility in having what amounts to behavior that is for all practical purposes independent of underlying rules but is nevertheless determined by them in any case we're having this conversation and uh I think we both realize that we're talking about free will and I'm discussing computational reducibility and he's saying in my opinion rather mystically there is something free about the way that we our our brains work and it goes beyond any kind of uh underlying rules but anyway they both realize that actually we had essentially the exact same conversation 30 years ago and um it's sort of interesting that insofar as one can think about Free Will so to speak uh yet for us humans given the same stimuli one will often respond in the same way and I noticed for myself actually that um there are cases where I'll be uh trying to resolve some question about some piece of technology or some such other thing and the same question will come up and I'll give an answer which seems like it's an original answer to me at that moment and somebody will point out you said the exact same thing two years ago when we last discussed this and so usually then I say good it's then it's consistent and and probably you know maybe it's correct maybe it's it is might or might not be correct but at least it's consistent let's see there's a question here from knock two do you think at any point we will create an AI Factory like specialized AI algorithms that create other AIS which do well at some specific task um well I think there are several different issues here one is given a particular like let's say a large language model can you create a more specialized large language model that does well at particular tasks I think the answer is probably yes it has not explicitly been done that way yet but I think it probably will be let me explain something about large language models one of the surprising things about chat GPT is that you can talk to it about all kinds of different things sort of any topic that's kind of out there on the web or in books or whatever it'll be able to yak about it it might say things that are factually correct it might make stuff up it might write fiction it might write sort of reasonable fact-ish stuff one of the things that I certainly notice and it's very frustrating thing really is like I was literally just looking at some output from gpt4 and I look at it and it's like well yeah sure it makes sense it seems roughly right and then I realized actually if I look in more detail it's not right it's very convincing sounding but it's just not right and in some respects it sort of sometimes more difficult to go back from the thing that looks convincing but isn't right to the thing that one would do if one just started from scratch but any case one can sort of talk to Chachi BT about a whole range of topics but one of the things that has been a big surprise and not very well understood is this concept of so-called few shot learning um where you can essentially tell it things like uh you know Ura um a a scientist from the 1600s who knows only about the things that were known at that time and blah blah blah and then you can ask it questions and it will sort of stay in character and it will it will kind of have have organized itself to only be using that part of its kind of one could say knowledge base that part of its linguistic base that is relevant to let's say scientists from the 1600s how that works we don't completely know because every time it produces a new word that is the next word that it's is putting down in the essay it's creating every time it puts down that next word it's running through the exact same neural network that it always does and the fact that it had this kind of pre-prompt that said here's this thing you know act like a scientist from the 1600s or something it's it's using that information as part of the initial collection of numbers as it ripples through the neural net making each successive word but exactly why the presence of that sort of pre-prompt um causes it to sort of organize itself to only be in sort of one part of its linguistic knowledge base nobody really understands um it's an important problem to to understand better but if you do do this sort of few shot learning and actually in few short learning you often also give it examples do it like this do it like this and it kind of gets in the groove and then will stay in character to those examples so to speak one would suspect that if one has done few shot learning for example prompting a various kinds to get it in a Groove that one could somehow just say Okay chop off everything else that isn't relevant to This Groove one would suspect one could do that but nobody knows how to do that yet I think it's a little subtle because it's you know people used to think back in the 1940s 50s things like that that if you did brain surgery on human brains and you or if somebody had some sort of injury to their brain and some piece of the brain was destroyed that that would mean that there were just certain things that person wouldn't remember but that isn't true what seems to be the case is that yeah there are changes but those changes are much more subtle and it's not just oh I forgot everything I knew about how to speak French or something or some very specific kind of content area it's not like in well you might think that memory will be organized in the brain with oh we've got this section of the brain that knows about this we've got that section that knows about this you might have thought that it was like that just like you know in a library physical Library you might have books about this topic shelved in this place and books about that topic shelved in that place I have to say now that I think about it I haven't thought about this in years that even for a computer the question of where is that memory stored is has become a lot more subtle than it was in the past in the past it might have been the case that you could readily say okay in the memory of the computer in in the well these days it would be many gigabytes many billions of of characters of memory so to speak where is the particular memory associated with um oh knowing some you know some particular number or some such other thing where is that stored in the memory of the computer it used to be more straightforward than it is today if you actually look at the memory of a computer it will be it will be sort of uh there'll be all these little sub pieces of memory and they'll all be kind of hooked together it's a complicated thing because when you allocate memory to use for a particular purpose in a computer you're always the the way memory allocate is working let me not get off on a big Side Track about this you can talk about it people are interested um it isn't the case that it's just like oh here's a big block of memory you're going to use it for this oh there's another program running here's a big block of memory for that it tends to be much more uh in sort of um in terms of the actual memory addresses it tends to be much more in a sense fragmented than that but that's even with computers when it comes to neural Nets the question of that fact that you just trained a neural net on where is that fact the answer is that fact might be distributed across a billion different numbers that characterize the structure of the neural Nets and we don't really know how that distribution across those numbers works it seems like oh it's the third decimal digit of this number is really important for that oh it's this part of that number that's really important for that but it's the whole thing collected together that manages to get the neural net to kind of uh generate the results it gets so I do suspect that there will be a way of saying well actually even though the sort of the the the memory of this of this thing is distributed uh in some sense across the whole neural net and all the hundreds of billions of Connections in the neural net and so on I think it will be possible to say let's make something which is a smaller version now now a thing people often do these days is to try and distill a neural net let's say you start off with a neural net with 100 billion connections you can run lots of queries through that neural net so you can know sort of you you can't give a sort of mathematical description of what the neural net does but you can certainly say I ran a billion queries through and this is what each of them did and you can use that as a way to train another neural net so trick people are starting to use is to say okay I've got a neural net with 100 billion connections let me see if I can train a neural net with only 10 million connections and see whether I can get it to do roughly the same as the 100 billion collection neural net does and there's reasonable success with this another thing one can do is to make the numbers that are specifying the the weights and the neural net uh not be precise you know uh 16 digit numbers but something that is just a few digit number so in any case I think the answer is that it will be possible to either sort of find ways to sort of carve out a piece of a big neural net and say this is the piece that is relevant for this purpose this is a piece that relevant is relevant for that purpose and I think potentially also to train smaller neural Nets from bigger neural Nets maybe just concentrating on queries that were relevant to some particular topic area now there's a quite different question which is making a factory for physical objects that's very much based on AI that's been a very long story and the factories uh there are surprising number of things that get done in factories even assembling very high-tech objects like cell phones and things like this where it's just not worth having a robot try and do it it's too hard to get the robot to work and get to work consistently it's better to have people just do it um it's I mean one can argue about uh it's you know in the end it's a sort of an economic question how much does it cost to buy the robot versus how much do you have to pay the people and that's a complicated issue quite different kind of topic but when it comes to robots making things uh sort of AIS making things in factories that turn out to be very mundane issues which are really hard like how do you pick something up this is something that comes up a lot for companies like Amazon which have giant warehouses where you know the sort of theory of Amazon is you can you can buy anything through it well that means those those inner things are on shelves and warehouses and they are in all kinds of different shapes and sizes and something or someone has to pick them out of the places where they're stored and put them in the box that's going to be shipped to to you and taking an object of any shape and picking it up and not breaking the object and not dropping the object turns out to be really hard now you know in a sense we've cheated for ourselves because most objects are set up most objects that one can sort of are worth buying from you know online you know e-commerce type type site are things that you would be able to pick up if you got it they're not things where you pick it up and it's this weird slippery thing and it slips out of your hands at the first moment um they're things that were made for humans to use so they are things which you know work uh set up so that you know you can with your hands with your opposable thumb and all that kind of thing you can pick the thing up you don't need to be an octopus to pick it up for example so in a sense we humans have made things to make it easier for ourselves to pick things up but even if you make a robot hand that's still you know four fingers and a thumb and has a certain amount of articulation it's still really hard to get it to grasp an object and pick it up and in fact sometimes the things that are best at picking things up don't look much like human hands at all and um this question of how do you learn how to pick things up is something which I'm kind of strongly suspecting is going to be solved through things a bit like large language models large neural Nets and so on that that will be solved fairly soon but that's been a big impediment in kind of making robotic lots of kinds of factory-like operations I mean there's there's things where what works pretty well is to have robots that do a very specific very defined task where the robot moves you know 18 centimeters this way picks up that thing moves it 12 centimeters that way and uh you know turns the screw to to um uh to insert it in something those kinds of things and then you can do a little bit better than that by giving the robot eyes so it can kind of visually see oh yes did the screw get put in the in the correct hole and so on um in a sense those kinds of eyes work a bit like a control system where okay so you know if you have a control system that's trying to be I don't know let's say cruise control for a car so and cause cruise control it's like okay normally you put on the gas a certain amount to make the car goes up in speed but if the car is supposed to be going uphill you have to put the gas on more if it's going downhill you have to take your foot off the gas maybe you even have to break a bit um that in a car there is this control system for cruise control for example if you have Crux of control in your car and you put it on and it says okay keep the car going it's 60 miles an hour let's say and then there's a giant you know there's a very steep hill and the car has to push the gas more and then maybe suddenly you get to the top of the hill and the the car would uh you don't have to put your foot on the gas as much how does the car not sort of start zooming forward well the answer is it has a controller a control system and what it's doing is it's sensing the speed of the car and it's saying okay the car's going a little bit too slowly put your foot on the gas more so to speak automatically increase the gas so that will make the car go a little faster and what can happen is if you do that and then then you say oh my gosh now I'm going 62 miles and I'm going too fast take my foot off the gas if things don't work right the car will just be going faster slower faster slower it'll be oscillating around and that's that's what happens if you have a controller that isn't set up correctly what ends up being the right way to do it is you have a certain time delay so you go a little bit faster but you don't you don't kind of um uh instantly respond to the fact you're going fast you just you know calmly respond a little bit and you don't you don't let it get into that unstable oscillating phase but that's a very typical form of control system such Control Systems have existed since the 1940s um and uh there's sort of this area of mathematical uh sort of engineering called control theory that is all about kind of working out when will a system be stable when will it be unstable when is a system controllable when is it possible to make that car successfully go at 60 miles an hour I mean if you have a car that's underpowered to go up a hill that's that steep well by golly you won't be able to get it to go at 60 miles an hour um and there are also questions about whether you can maintain stability whether the the system will always show certain kinds of of instability and that there are lots of control systems we see all around us for example thermostats for keeping temperature constant temperature that's a very common type of control system uh usually the buzz term is a PID controller is a very simple kind of controller that um uses a certain algorithm to keep at a fixed let's say temperature same is true more elaborately with autopilots for planes keeping a certain uh heading independent of which way the wind is is pushing the airplane and keeping a certain altitude those are things that are done can be done with these sort of Fairly traditional Electronics rather than computer-based controllers by the way one example of a more complicated kind of controller is the flight controller for a drone um where and that sort of only became possible within the last decade to really have uh those those controllers are not typically done with simple Electronics we just have a few electronic components they're done with a computer and the algorithms are more complicated to make those work and fly in a stable fashion and another famous early controller was the automatic windshield wiper where it was you know only if you sort of see rain do you sort of operate the windshield wipe it was an early application I think of transistors it's just I think they think the first controller for that just had one transistor in it whereas your average microprocessor these days might have a billion transistors and and to make a computer that we have but any case in sort of factory automation the idea of control systems that sort of keep things at in some fixed way that's a that's a very old idea uh often even Vision systems where the robot has eyes are being used kind of like a control system just say oh we just need to make sure that the that the screw goes right into that hole and we can't you kind of oscillate on each side and you you know put it right in um the uh the question of whether one can make a kind of um um sort of how one makes a kind of general purpose Factory with AI it's a difficult question I mean a typical actual Factory even when it has lots of robots in it it is non-trivial to reprogram the factory it's it's gotten better I think uh Tesla pioneered some robotic construction techniques uh all car companies I think at this point use significant numbers of robots on their production lines but if you say oh last week we were making this kind of car next week we want to switch to making a completely different kind of car bringing up the line the production line to do something quite different has traditionally taken a while like months my impression is that that's time has gotten down considerably but it's not like you just tell the robots I think uh okay just reconfigure yourselves to make you know here let me show you this new car assembly that we're going to make let me show you the instruction book now reconfigure yourselves to operate according to this instruction book that hasn't yet become a fast thing to do that will come I mean one of the things that is totally remarkable about llms is you can actually give them things like instruction books and have them read the instruction book and sort of figure out what to do from that now they don't necessarily do it completely reliably so you have to have all kinds of safety nets and checks to make sure the thing didn't just go crazy and have a little brain glitch so to speak that caused it to just do something do something quite wrong um but I think it's the thing that will be a definitely a coming thing that one will be able to basically say I want to make this here's the manual for how to make this or even just here's the here's the thing that's been made uh you know go ahead and and put it together you know I don't think I've ever seen a demo yet of something like a Lego construction where you know you have all these pictures of how the Lego books put together and um um I find them hard to follow often but that's just me um but then to be able to have an AI system that can just read those instructions understand the pictures put the Legos together that's step one step two is just look at the picture on the box of the final completed thing and figure out how to put how to take the components you have and put them together to make that thing that will come I'm guessing that's that's not that far away a couple of years maybe um to be able to do things like that and that will certainly help in making sort of more robotic AI enabled factories let's see uh looking at some of the questions that have come in about this particular point so spare parts is asking any thoughts on using physics simulations versus the real world to teach robots you know people there's this technique called reinforcement learning which is actually kind of related to feedback control systems that I was just talking about they've got a lot of the same mathematics they grew up in two slightly different communities and so they have a lot of different language which is super confusing to people um uh because you see things which are like very similar but not quite the same described in quite different ways but you know one of the ideas of reinforcement learning is you've got this robot and it can try things in the real world and see what happens and use that as its way to train itself about how things should work in a sense that's what we humans might do when we first learn to you know use our hands or something and yes you know you stick your thumb somewhere near your mouth and eventually you discover this is how to put your thumb in your mouth or whatever um and uh that's something which you kind of learn by experience interesting things in the world quotes robotically so that's one approach um if you are sort of making a self-driving car do its thing you can say well let's try it on this kind of Road let's try it in the snow let's try it in this case in that case that's sort of one possibility the other possibility is to essentially make a video game type environment where you are supposedly successfully simulating what the self-driving car would do what what its environment would be and what its mechanical response would be to what's going on and then train it that way what's tended to happen is that it's just much cheaper to run endless video game like simulations for training than it is to train anything in the real world where things are sort of where a robot is actually walking around and banging into things and and bashing its head and having to be replaced and this foot falls off and you have to replace it that's all a big pain relative to just having the thing existence on virtualized game environment it's sort of interesting that when we talk when we talk about educating humans about things there are lots of purposes where it seems much better to just do it in the real world than to experience it in virtual world but the thing about it is that's because we're sort of tuned to deal with the real world experience things at the speed that the real world happens whereas if you are training in AI the AI could be running at sort of a thousand times real world speed um training itself against many many more scenarios now that's all well and good so long as the simulation is accurate enough that you are capturing what you need to capture if you train the self-driving car based on a model of snow and it's not how snow actually works then it's going to have learned the wrong thing it's also the case I think that a lot of that training is probably in the end going to be unnecessary because what's happening is one's just getting the AI to basically learn certain rules about the laws of physics and things like this which you could if you were able to deal with it differently just say these are the laws of physics they're described by these equations or rules or whatever else and but because you're saying everything's going to be learned by a neural net the neural net doesn't have any way to directly solve equations or whatever else so you have no choice but to just say learn by example learn by example learn by example whereas if you could combine that with something which was just using kind of mathematical science or something to just solve the equations you wouldn't have to go through all that training and that's a powerful direction that one's just starting to figure out I mean a lot of things we've done with for example the Wolfram plug-in for chat GPT is an example of kind of combining the ability to do sophisticated computation with the pure sort of linguistic and Common Sense kinds of capabilities of an llm and I think that will be increasingly a story of knitting together kind of deep computation and in a sense scientific knowledge of the world together with this kind of learn by example type thing um a quick question here from Pedro is that computer power then that speeds real progress in for example llms AIS things like this so you know I think I mentioned this here before the story of neural networks is is such a strange story in the history of Science and Technology because neural Nets sort of modeled on how brains how we think brains work but they were kind of defined back in the 1940s and you know at that time people would say we've got a few neurons five neurons at most that we set up with an electric circuit and so on and then now in kind of chat GPT there are many millions of neurons with hundreds of billions of connections between the neurons it's a very big thing and the fact that in chat gbt we got something that can meaningfully write essays and so on and at what point how many neurons do we have to have to make that work nobody knew and even beyond that there were other things that were done that were very much sort of engineering Solutions of okay yes you can get you know a chat gbt like system to complete sentences that you start and so on but but it will go off track it will lose its train of thought it will do all kinds of crazy things what was important there was that it was trained using reinforcement learning with human feedback to kind of stay on track you know yes you're writing a poem this is how poems work yes you're writing an essay this is what to expect yes don't produce all kinds of uh crazy bad words when you respond to something and the way that was done it's a little bit like a robot learning things in the real world what was done one was that a sort of prototype of chat gbt was put out there in the wild well not quite in the wild but people were brought in to say okay go have a chat with this thing and tell it comment tell it yes that was a good piece of chat no that was a bad piece of chat here's what was wrong with that here's a piece you should take out here's a piece you should add to give that kind of feedback and that was turned out to be I think more crucial than people even recognize yet so the fact that chat gbt actually worked in a useful way that kind of Direction human Direction so-called reinforcement learning human feedback rlhf um that those steps were more important than people expected it's kind of an interesting thing because in a sense the the people who first did that kind of human feedback for chat gbt their views about the world were in a sense burnt into the very first versions of chat GPD so it had all kinds of political views and this and that now because that just happened to me the views of the fairly small number of people who did that reinforcement training uh subsequently it sort of got more more generic size by having more people and and be it by being specifically sort of trained to not go in the specific directions of the people who first trained it but it kind of gives one an idea of kind of the the role of training and and the role of sort of how do you govern the AIS well you know you imagine you've got people feeding in these prompts giving these reinforcement training to the AIS and you know I think it's an interesting question sort of how do you do government democracy whatever in the land in the time of AIS and you can sort of imagine it's just all the people in the world provide reinforcement training all the people in the world or in a country or whatever or in some particular Community provide essentially prompts to the AI to tell it what they want it to do each one telling it maybe pulling it in a different direction then it's up to the AI to figure out how to sort of merge those together a challenging even philosophically sort of impossible thing to do let's see um look at something somewhat different here uh keflas is asking what do you think about sources of energy now and in the future or developed and developing countries um the uh interesting question so I mean I I get exposed to a certain amount to this because I know a lot of people who are interested in what usually gets called Deep Tech which is uh kinds of Technology problems which would be very important if they were solved and but they're hard to solve and so energy generation is one of them so I mean if we look at what's available now well you know there's a lot of energy that's that's sort of uh uh provided to us by all those trees that existed in the Carboniferous period and turned into into oil and so on crushed underground and that's been for the last hundred years or so that's been a big source of of energy in the world then there are things where you know there's hydroelectric energy where you're basically using the fact that you've got water I mean people used even before electricity people had water Mills where they would just use the flow of water um in a river to determine to to run a a a wheel to to produce energy but the fancier version of that is to put a dam in and to have water sort of water high water on one side and low water on the other side and as the water runs through the dam it runs through electric General creators that um it the the flow of water spins around the the wheels in those electric generators and generates electricity I mean it should be said that the vast majority of energy that people I would say care well is this really true yeah I think the most convenient form of energy is probably electrical energy people find it much more convenient to sort of package things up as electrical energy in batteries or on electric power lines than to have other forms of energy now there are other things I mean you can have uh you know gas for example natural gas and you can just burn it directly to produce heat um but electricity has been a very flexible way of of uh of of storing transporting uh having energy ready to be used in different ways to make light to make heat to run computers to run uh to to drive um mechanical things and so on it's a very conveniently convertible form of energy so a lot of types of energy Generation Um involve electricity so the question is then how do you get electricity what's what are some good ways to get electricity well you'll you'll need some kind of energy that you can turn into electrical energy so you know hydroelectric energy dams geothermal energy um the idea of geothermal energy well there's different kinds there's there's kind of um shallow geothermal energy and there's deep geothermology the Deep one is probably the most interesting case um that uses the fact that the center of the earth is really hot compared to the surface the average temperature you know a little bit under the surface is like 50 degrees Fahrenheit um the temperature of the center of the earth is many thousands of degrees Fahrenheit there's there's partly there's just Relic heat from when the Earth was created 4.6 billion years ago that's been kind of locked into the insides of the earth about half the heat of the earth and the other half comes from the decay of radioactive elements inside the earth um producing uh producing nuclear turning nuclear energy into heat so the way that deep geothermal energy works is you uh it's a little bit like the way that you might drill for oil you drill down until you get a deposit oil now you're just drilling down anywhere on the earth and you drill a mile or two down and a mile or two down it's pretty hot you're getting closer to the center of the earth below them below the the crust of the earth which is like 50 miles thick there's this um you go you go into the mantle of the earth which is sufficiently hot but the rock is liquid there eventually you get to the center of the Earth where it's solid again because of the pressure is is preventing it from becoming liquid but um the uh so anywhere on the earth you drill down you know a mile or two down and it's really hot it's certainly hot enough to boil water and so then the idea is you put sort of you you you go you drill down you pump water down or some other fluid down on one side at the bottom of your your big uh well the water gets really hot because the Earth is really hot there and then you pump it back up and you take that the water that you just heated and you use that to uh to drive to make a kind of a uh to drive an electric generator for example it's a general principle that you can use heat to make things like electric power uh heat there's a bunch of molecules running around a kind of a random way and each the molecules individually have lots of energy associated with them but the heat heat is a sort of disorganized form of energy and something was figured out in the early 1800s was the idea that in order to make use of heat you kind of have to have sort of a hot thing and a cold thing and in a sense the the way that you make use of heat is by having a flow of heat from a hot thing to a cold thing so there's there's sort of always a hot Reservoir and a cold Reservoir so in the case of geothermal energy what's happening is you start off with the water or whatever it is usually people talk about using things other than water um high pressure methane maybe is I forget uh some some high pressure gas I think is better than than water or steam um uh yeah there's a the um you um uh no it's not methane it's another I I've forgotten um in any case the the um you uh um you're kind of it's cold at the top you pump it down you get it really hot and then you bring it back up again and then you're kind of getting a flow of heat from the hot to the cold and using that to drive something that can can make for example electricity so what are some other ways to make energy um another way well another thing you can try to use to make energy is like the tides um the uh the the effect of the Moon pulling the water on the earth in sort of the direction of the Moon and away from the directional moon on the opposite side of the earth uh there are the the you know the water goes up and down you can potentially use that like a sort of uh a daily version of a hydroelectric Dam doesn't seem to work that well um another big thing you can use is wind uh that's why there are wind turbines all over the place um I'm not sure how terrific that that source of energy really is um I mean it it uh the wind turbines are extremely expensive to make um and uh uh it is the case that there is the the rotation of the Earth does uh and and also the um uh the fact that hot air rises and so on those effects together produce flows of air on the earth that are wind and uh there are plenty of places where there's lots of wind um and particularly over oceans and things where the wind is not stopped by it by by um uh features on the on the earth and so on there's there's plenty of wind and so long as you don't have too many wind turbines all lined up behind each other where one of them is kind of stopping the Wind by you know the wind is is used to turn the turbine but that's slowing down the wind and then you have another turbine that's uh sort of in the shadow of that one so long as you don't do that there's sort of enough wind to go around uh my impression is that a lot of these methods of energy generation very detailed thing whether uh whether it really you know how much does it cost to construct the wind turbine how does it much does it cost to maintain the wind turbine all those kinds of things I mean a very important feature of things like wind and and uh geothermal energy and so on is that they it's not going to run out you know until I suppose if we if we try to extract enough energy from the earth we might be able to slow its rotation down but you know we humans are just so unbelievably far away from from doing something like that it's we're much further away from doing that by Pruitt could probably work out how many hours of magnitude compared to uh sort of using up all of the oil or natural gas that got sort of uh created a few hundred million years ago um when trees were first on the land and and um uh sort of collecting energy from sunlight and then getting fossilized and turning into into things like oil and so on um so you know all of these things eventually uh the the energy eventually you take all these sort of forms of organized energy and eventually you turn them into what to us seems like disorganized energy namely heat but in the case of like slowing down the rotation of the earth it's just not not even close I mean in in um to the kind of thing that that we could achieve so other forms of energy another big one is photovoltaics which is taking uh the light from the sun um and uh turning that into electricity and it turns out to be possible using semiconductors to directly turn uh using the the photoelectric effect the fact where you can have a photon of light come in and it can make an electron it can take an electron that was otherwise just happily hanging around some atoms it can kind of make that electron turn into something that makes an electric current um it's been a very challenging thing to figure out how to make efficient photovoltaic cells uh you see these big solar Farms so to speak with um usually purple blackish type um uh silicon um uh uh solar cells and um uh the efficiency of those things is just not all that great um and if if somebody could discover some new kind of compounds some new material for which photons from the Sun are the energy that protons come in from the Sun hitting it produces more electricity it's certainly possible that that could happen there's nothing that that is sort of a physical limitation on the efficiency of those things and that would have a dramatic effect um on on how effective that how effectively that works so another big area of energy generation is nuclear energy of which there are really two kinds fission energy infusion energy uh fission energy comes from the breaking up a very large nuclei like uranium and plutonium and fusion energy comes from the the pushing together of small nuclei like hydrogen it's just a feature of nuclear physics that both of those activities make energy both breaking apart a big nucleus and to make smaller nuclei and putting together small nuclei to bigger nuclei you might say well what's the what's the nucleus that everybody wants to be it's iron 56 that's the type of nucleus that has sort of the um that has is the most tightly bound nucleus it's the one where if you you know break apart uranium eventually you'll get down to that put together hydrogen eventually you'll get to that that's why for example the crust of a neutron star is probably made of iron 56 for that reason but in any case the the um so in fission energy what you're starting off with is uranium which you mine from the ground and very conveniently the half-life the time for the decay of uranium is in the in billions of years a couple a billion years so there's still uranium that was created when the Earth was created was created by nuclear processes and stars and it was kind of locked in on the earth and it can be mined and it's still radioactive and that's kind of the thing you start from in making a nuclear reactor now there are many different layers of what happens there you can make you can make a nuclear reactor make new radioactive elements that you can then use in a nuclear reactor so-called breeder reactors and there are a whole variety of different methods for for doing um for using uh for using that but but essentially a nuclear reactor is uh is making heat from the fact that there are uh uranium um okay so so the way a nuclear reactor works is a uranium nucleus spontaneously breaks apart at some rate the rate is quite low because it takes a couple of the half if you have a big lump of uranium 235 a particular isotope with uranium with um total of 235 protons and neutrons in it with that type of uranium there's a different isotopic uranium-238 which is stable doesn't occur at all but uranium-235 which you can separate out with great effort using things like centrifuges um you separate it out it's then radioactive it decays it decays by spontaneous fission that means that basically the uranium nucleus you know after a billion years or so just boom it falls apart and when it falls apart it produces a bunch of neutrons among other things and those neutrons have quite high energy and the thing that leads to a so-called chain reaction is that once one uranium nucleus falls apart it produces neutrons that then hit other uranium nuclei they poke other uranium nuclei and that poke causes those other uranium nuclei to fall apart then they produce neutrons then those neutrons go and make other uranium nuclei fall apart and you have this Chain Reaction where you have more and more and more neutrons produced more and more and more uranium nuclei produced it goes exponentially um in in that way if you want to make a nuclear weapon that's what you want to have happen is to have that Chain Reaction happen as quickly as possible and produce as much energy as possible if you make a nuclear reactor you have to have so-called control rods or moderator and what the control rods do or the moderator does is it absorbs neutrons so all these neutrons are being produced but you want just the right number of neutrons to be sort of freely flowing around that it makes a bunch of other uranium nuclei kind of explode just enough to make the power you want but not so much that the whole thing's going to go out of control so you know typically in a nuclear reactor there'll be these control rods that are that are pushed inside the core of the nuclear reactor and you kind of pull them out as you pull the control rods out the neutrons can flow freely and so there are sort of more neutrons there you push the control rods in they absorb the neutrons and the thing sort of calms down so to speak and again it's one of these control systems that typically operates you know how far out should the should the control rods be what temperature should the in the core of the reactor be when things go very wrong the core of the reactor's so-called melts down which means that it gets so hot that it becomes molten and that's very bad because the the nuclear reactor was engineered by to be a solid nuclear reactor of a certain shape it wasn't energy had to turn into a pile of liquid liquid uranium or something and that's happened a few times in the history of nuclear power and it's very bad but um in any case so nuclear reactors have this feature you still have to mine uranium but you don't need very much of it at all to to to uh produce a great deal of power and you can also make your own fuel for a nuclear reactors from nuclear reactors themselves what's difficult is sort of it's all a bit you know it can be a bit dangerous the um uh you have to engineer it to be so that nothing could possibly go wrong but the level of of nothing possibly going wrong usually the the tolerances for the engineering are maybe a factor of two have nothing going wrong whereas I don't know you make a plane or something it's more like a batch of 10 I think so to to have it takes some effort and then you have to make these um um uh you it it requires a lot of Maintenance of a nuclear reactor for example the fact that there's all this radiation all these all these fast particles going around you know when you have a metal container for the nuclear reactor that metal is continually being damaged by all these particles hitting it and so that's something you have to deal with and and uh and eventually replace and a lot of nuclear reactors are getting into the 50 years old and more kind of time frame and some of them wasn't expected they would keep working this long as it was thought radiation damage and so on would stop them working but there are new designs of nuclear reactors so for example one I was just hearing about is well what about if you put the nuclear reactor deep down in the ground you know a mile down or something like that then um the uh then even if something goes wrong it's not really a big deal because gosh there are deposits of uranium down in the ground which are also radioactive and so on and even if there was a nuclear explosion a mile down you wouldn't even notice I don't think you'd even I think actually a good question whether uh what kind of a little earthquake that would produce a mile down I I'm skeptical it would be much of an earthquake you probably it'd probably have some effect but not much um the the amount yeah particularly if it was an actual nuclear explosion a lot of nuclear tests were done underground um not terribly deep underground and uh they certainly you know they made little earthquake like things but they're not very impressive earthquakes um and uh you know an actual earthquake releases a lot more energy even than a nuclear explosion so okay so that's on that side of of um uh nuclear energy the fission side there's also the fusion side people have been so the sun is powered by nuclear fusion hydrogen atoms hydrogen nuclei uh being going so fast that they fuse together they they're going so fast because in the in the center of the sun it's 10 million degrees centigrade and that means that the that they're going really fast and they have to be going fast because you have two hydrogen nuclei the two protons protons are particles that electrically repel each other and that means that when two protons get close usually they would just sort of bounce off but if they're going fast enough they get over that repulsion and they get to the point where they stick together and eventually make a helium nucleus um and so that process when when they do that they release a bunch of energy that's all really good and uh you all you have to feed in is a bunch of hydrogen plus a very high temperature the problem is the following in the case of the sun the sun is held together by gravity and there's uh nuclear processes going on throughout the Sun so to speak um if you just want one of these things in your backyard you have to make something that's sort of as hot as as somewhere inside the Sun and you have to make sure that the plasma the sort of the gas with all its electrons stripped off that you get at very high temperatures is is just kept confined enough that the protons can actually run into each other and the thing doesn't just get so hot that it sort of you know just gets out of everything in the case of the sun it's all held together by gravity throughout the whole Sun but in the case of just a little thing in your backyard you have to kind of keep something at tamel and degrees Centigrade well how do you keep anything at 10 million degrees Centigrade you know the the if you have I don't know a Tungsten you know some some material that uh can withstand high temperatures it um uh the um uh the maximum you're going to be able to get up to is a few thousand degrees um you're certainly are not going to get to 10 million degrees so the only way you can sort of keep things bottled up at 10 million degrees is to use something other than a material container and so what gets used are magnetic fields um and that leads to this idea of uh plasma confinement Fusion where you are kind of um uh you're trying to keep this plasma at 10 million millions of degrees Centigrade you're trying to keep it confined and there are these different very elaborate kind of shapes to a very common tokamax and stellarators are these very weird shapes of magnets that try to keep the this uh this plasma sort of all bottled up to the point where you can get a release of um of energy from from the protons running into each other and recently in a slightly different way with lasers there was an example of being able to release more energy than you put in a nuclear fusion but there's been it's been a long-running story when I was a kid people said it's just around the corner you know uh nuclear um nuclear fusion power will be here uh you know in just a few years in the early 1960s well it's still not here and it's turned out to be a very difficult problem to confine these these plasmas now there are just recently last three four five years there's been a lot of interest in doing this a lot of a lot of companies started uh some of them with different ideas about how to do it different configurations the magnetic field different materials to make the magnets to have things associated with magnets and so on different computer control systems for the magnetic fields all those kinds of things all in an effort to make fusion power which if it works will be just great because it's some something where there's no lack of raw materials you just have to have hydrogen and then uh it's sort of free Power for the world now there are a few other things on the horizon I mean there are a few um less common cases so one of them is a so-called cold fusion so this was uh the the sort of hot Fusion is what happens in the sun happens in these various devices people are trying to build and that involves you've got all these protons in there you know millions of degrees centigrade and they're going fast enough they're just going to fuse with each other but there's the possibility that Fusion might be achieved some other way without making everything very hot and about true when was it 30 years ago um there was a claim that cold fusion was possible and um that in particular uh an element called Palladium um was sort of a big part of that and Palladium turns out to absorb hydrogen it dissolves hydrogen hydrogen uh in Palladium so Palladium you have this metal thing and you start putting hydrogen into it and it just keeps on packing in protons keeps on packing in hydrogen nuclei you can just keep putting in tons and tons of hydrogen and the hydrogen kind of Finds Its way in between the atoms of Palladium and so on and somehow a piece of Palladium will just absorb a huge amount of hydrogen so the thought went well maybe it absorbs so much hydrogen that just by its crystal lattice by putting those those uh those hydrogen atoms in this crystal lattice you can pack them in so much that eventually they'll sort of get close enough that Fusion can occur and at the time people claimed this a bit and then people claimed it wasn't true and there was a big sort of flap about it and the end result was people sort of stopped really working on that but there'd been a small number of groups around the world that have continued to work on Cold Fusion it became kind of a a oh no that can't possibly work it's it's nonsense and it must be a fake experiment if you're finding that it works um my own guess is that something like that will work in the end how it will work why it will work I'm not sure we know but I think the very fact that you can just pack so many hydrogen atoms into some of these materials and they're kind of arranged in this crystal lattice um it it's kind of makes one think that somehow it will be possible to get them to be sort of close enough sort of maintained by the crystal lattice that a fusion process could occur don't know how I don't know when if that worked it would again be a very exciting kind of free Power for the world type type of uh type of story I think the thing to realize is oh there's just a lot of features of materials were things are happening at a much different scale than you expect like when you tear something when you break a piece of metal or chalk or something like this you might say well it just breaks but it turns out there's enough energy in the breaking of some of the atomic bonds that you produce a tiny flash of light you even produce x-rays when you just break something not many but there are very high energies associated with just Atomic bonds um in in just your average material I think um in uh it's also worth saying that the theoretical deduction of what should in principle be possible to do with respect to Fusion cold fusion and so on there's no way one's going to be able to work that out theoretically I mean if one's very lucky one will get it but I think it's not likely similar to the way people are pushing towards higher temperatures superconductors higher temperature materials where you have perfect electrical connection really nobody knows how to make even the The Fairly high temperature superconductors that are known and by fairly high temperature I mean the temperature of liquid air or something um which is not that pot so to speak it's pretty cold um the uh even knowing how those kinds of superconductors work is beyond what's been successfully figured out in physics and to be able to predict correctly oh we're going to have a superconductor that will work at like say room temperature it's it's much more likely I think to be found empirically maybe with some indications from Theory than otherwise now you know I'll mention a few other sort of other power opportunities another one is how do plants work well plants take in sunlight and they sort of effectively use that to produce energy in some sense and they do that using chloroplasts which contain the the protein chlorophyll and chlorophyll absorbs a photon and somehow and produces uh uh sort of generates does things with electrons eventually to generate something which can be used to sort of have organized energy in the plant that organized energy in the plants is what got bottled up so to speak a few hundred million years ago and turned into oil it's also what makes you know would be worth burning and things like this but in general the um uh the point is if you could have your own sort of artificial chlorophyll artificial chloroplast that will be another potential way to sort of make energy from sunlight sunlight is a very very large source of energy you know the sun however much sunlight we use we're not going to have the sun go out as a result of it um let's see oh yes there are all kinds of schemes for different sorts of things I think there's one a friend of mine is doing that uh for portable tax this is an idea where light from the sun has a certain distribution of wavelengths and uh the photons from the Sun are not specifically tuned they have a whole distribution of wavelengths they're like white light like a if you put slight from the Sun through a prism you'll see that it's broken into you know all the all the colors of the rainbow well what if you just make light at a particular frequency a particular wavelength can you make a more efficient converter from light to electricity than a general uh photoelectric effect thing and the answer seems to be potentially yes and that's very interesting because if you can increase the efficiency that's a way of increasing the efficiency not by virtue of changing the photovoltaic substance but by changing the incoming light and you can make light of a fixed frequency uh with by essentially just using heat um with uh um with the emission lines from gases for example that um where the the um uh the gas will emit light at a particular frequency and then you kind of turn that into electricity so that's an example of one um uh question being asked what will happen when oil runs out will there be a shift to clean energy well before this happens uh I'm sure the answer is yes you know I remember back 25 years ago 30 years ago I would talk to people who are in the geology business and I would say how much oil is there on the Earth and they would say well uh eventually they would say look it just depends how much you're prepared to spend to get it out the amount the total amount of oil that exists somewhere under the surface of the Earth is huge sometimes it's in little pieces and rocks and you have to do you know fracking to get it out sometimes it's in giant reservoirs sometimes it's very deep sometimes it's in very inconvenient places under the ocean all these kinds of things but there was a there was a period of time when people said the oil is just going to run out there's just not going to be enough oil on the Earth and I think that just turned out not to be true it just turned out there were more and more places that oil could be found it was just a question of they were in very inconvenient places and it became more and more expensive and energy consuming to actually mine the oil out so I don't think I'm I'm skeptical that it will run out the economically accessible oil that can be uh mined out at a reasonably low price that might run out um but you know it's just a question of price as soon as that's running out and you still need it the price will go up to the point where it becomes worthwhile to get that oil out as well I think the uh uh you know there's been this big push for all kinds of different reasons I mean one reason is that the economically accessible oil is certainly not equally distributed on the surface of the Earth there are you know particular countries that lucked out in terms of having sort of easy to access oil oil resources and that's led to all kinds of effects and the kind of uh so the political economy of the world so to speak um and uh I think that it tends to be the case that these other forms of energy are a bit more kind of globally accessible I mean there's sunlight almost everywhere yes it you know if you're above the Arctic Circle or something then for half the year you don't get to have sunlight and you don't get to operate photovoltaic cells it tends to be the case that for example who people who think about high altitude drones that would be flying at sixty thousand feet and just keep flying continuously powered by sunlight there's a pretty sharp cutoff that above a certain North a certain Northern or Southern latitude um you just can't fly a thing with a certain efficiency I'm above 50 something degrees north latitude I think the things you can make these days just can't keep themselves Aloft just at least at least in one design um by by using the current efficiency of photovoltaics um and so there are limitations there there are places that have more wind there are places that have geothermal energy because they're on um uh for example plate boundaries where yes there are earthquakes and geysers and things like that but there's also geothermal energy um there's places where you can readily make a dam in a river and have hydroelectric energy Etc there are also places where there's uh there's a limited number of places on the Earth where uranium is is economical to mine but as I said you don't need a lot of your of radioactive uranium to get started on this sort of cycle of making nuclear fuel so uh I think that that's some uh yeah that's the way that works um well there's a question here about nuclear energy do the dangers nuclear energy pose a problem or do the pros outweigh the cons um in the situation uh you know the nuclear reactors as they're currently built are very complicated things and complicated sort of one-off Engineering Systems are hard to get precisely right the number of nuclear accidents that have occurred in the history of nuclear power is not that large it's basically let's see I can probably even list them all 1956 wind scale in England uh 19 70 something Three Mile Island in Pennsylvania uh 1980 mid-1980s Chernobyl in Soviet Union and then Fukushima in Japan about a decade ago I think those are the and each one happened in a different way for different reasons um it's really hard to work out what will happen if something goes wrong you know I remember to tell a little historical story for for me back in the in the early 1980s people were very keen to sort of push the idea of nuclear power and to prove that the current designs of reactors were you know 100 safe always always hard to prove something's 100 safe but one of the things that had happened at the wind scale accident in England is that radioactive gas was released into the atmosphere not much but enough and um a Three Mile Island uh Radioactive gas was not released into the atmosphere the um the the the accident was was contained so to speak um and so there was an effort to sort of prove it was all going to work and I remember uh I was I think probably all the people involved in this in this story uh except for myself happily are now dead but but um the uh um was the sort of effort to um uh sort of prove the safety of nuclear reactors by by showing new designs couldn't possibly fail and there was some big commission that was being put together to show that and at that time uh I was much younger than I am now but I knew quite a bit about sort of computer simulations of things and so the theory was oh we're going to do a computer simulation of this nuclear reactor I'm going to prove that nothing could possibly go wrong and I was like that's never going to work you know you're never going to be able to say you know you can you can look at certain scenarios and things but you're never going to be able to say nothing could possibly go wrong so I said okay I'm not going to be involved in this so then a few years went by and then the Chernobyl nuclear accident happened and I so I asked people who've been involved in this thing so you know if you were like nothing could possibly go wrong a lot did go wrong at Chernobyl and it did release radioactive gas into the atmosphere and so on and you know how did that happen and the answer was well it was a Soviet reactor and it had a bad design Etc et cetera et cetera and the American ones are much better probably true Etc et cetera Etc but you know and and I mean Chernobyl was a very famous accident in the sense that um oh gosh it it just produced so much a lot of mess I remember I visited Northern Sweden um a couple of months after Chernobyl happened and there was a whole big plume of radioactive gas that had been blown by the wind or actually radioactive dust had been blown by the wind and that caused uh a lot of radioactivity in the food chain and the reindeer were you know radioactive and it's just a huge mess um the uh the actual things that happened there um it was a failure of the control system of Chernobyl and this whole business about control rods and whether the control rods can be pulled out and pushed in and all this kind of thing one of the things that's famous for its sort of uh engineering issue was you know you'll have a big system like a nuclear reactor and they'll have warning lights and things go wrong it's kind of like a red warning light will come on but you have a big complicated nuclear reactor there's an array of a thousand warning lights and what had happened was that oh the thing was a bit old and it was a bit you know sort of crotchety and so on and it was always running with lots and lots of warning lights on and you know I I often use this this example because it's really worthwhile you know if you have a program and it's producing error messages and things you really want it to run with no error messages not just a few error messages that you don't understand but no error messages partly because when you have a few and then you have a few extra ones you don't even notice the extra ones and that's kind of what happened at Chernobyl is that well it was always running with a certain number of warning lights but then it had more warning lights and then well then what happened was an explosion happened and then the whole thing was full of warning lights um but I think even before that had happened I don't remember the precise details of what what occurred but it was at a weekend I think and um it was all a bit of a mess in terms of the chain of command and you know people calling people and not being able to get anybody on the phone to say what do I do with you know the operators of the nuclear reactor were saying you know oh there's this extra warnings that are on what do we do about this Etc et cetera et cetera but in any case I think uh with nuclear reactors there are lots of new designs that are uh very different I really kind of like this design I just heard about that involves burying the nuclear reactor deep underground that seems like pretty good idea it seems like a that's one of these uh really there's not a lot one can see going wrong um uh famous last words but I I think that one seems very well contained um but uh I mean I my own guess is that um um um uh you know nuclear power is probably a pretty good idea I mean it really depends it depends on how careful you're prepared to be and how careful you're going to insist on being because if you insist on being so so careful that everything is you know 50 times over engineered it will never be cost effective if you say a factor of two over engineered um you know maybe that works but then you have to kind of not do anything kind of you know not miss things that um uh uh you know not make mistakes so to speak and um it's you know there are challenges there um I feel it it's interesting spare parts is commenting the death rate for nuclear energy is around point zero four deaths per terawatt hour which is similar to wind and solar yeah well I don't know about solo I don't know how I mean with wind turbines uh definitely bad for birds and bad for humans who try and maintain wind turbines because they're awfully you know it's awfully high off the ground um the uh um I'm not sure what goes wrong with with solar I mean maybe you have these things where you're collecting a bunch of solar energy and things get really hot I'm not sure I mean maybe um uh you know somebody falls off a roof when they're installing some solar thing um the uh uh Haley is commenting nuclear is safer than coal because people are more cautious when the stakes are higher that's that's an interesting claim um I think um uh you know it's I would suspect that with modern engineering modern engineering design methods that it really is possible to make much safer nuclear uh reactors and there's a question here about what do I think of small modular reactors I've not studied them in great detail I know a bunch of people who are working on them uh on on the face of it they seem like a good idea I don't know the details um and I really need to get going in a second here um the uh um let's see there are questions here about some from spare parts about connection between computational irreducibility and extracting usable energy can energy be mined with computation uh that's a long story and it relates to this thing called the second row of thermodynamics which I've studied quite a lot over the last 50 years I have to say um and that has to do with this question of whether the energy of all these molecules running around when something is hot is that useful energy or is that just heat that isn't useful how do you line all those molecules up to be able to turn a wheel to turn an electric generator something like that and yes the the story of kind of how do you go from the apparent randomness of heat to something more organized is a story of kind of computational irreducibility and yes it probably is the case that there are places where you can make use of energy more effectively by using computation to know what's going on I mean I wouldn't be surprised if there weren't situations I uh many of the ones we've talked about well in in the case of wind energy uh you know usually the wind is consistently blowing in a certain direction over a wind wind turbine but um if you were trying to deal with you know something whether just a little bit of wind blowing in different directions but you have this all these sensors and you can figure out oh the wind is about to blow this way turn the turn the kind of windmill in that direction and you'll catch the wind that way and then you know do this computation turn in another Direction catch the wind in that way that's a place where you can use computation effectively to collect more energy to not have that energy seem like oh it's wind going in random directions it's yes it's sort of random but you can predict it enough that you can kind of pre-wire things to be picking up that energy all right I um Reebok is commenting nuclear is not a good thing until we have some way of disposing of the waste products yeah that that's a challenging thing it's like where do you put the waste and um I think the the main issue is [Music] um uh what was it Yucca Mountain is the place in the US where a bunch of nuclear waste um put sort of under the mountain and the problem is when you do that if it isn't deep enough it ends up being able to get into groundwater and then it seeps all over the place the radioactivity can seep all over the place and even this let's bury it and put signs up that say you know that will for 10 000 years tell people don't go here after 10 000 years the radioactivity will have dispersed so to speak just by radioactive decay I kind of like this is one reason I kind of like this idea of just bury the reactor a mile down because uh you know things if you have something that's radioactive and it's under a mile of rock it really isn't going to do anybody any harm or anything any harm and I'm not quite sure why the depth of um why it isn't the case that when one thinks about nuclear waste disposal but one isn't thinking about deeper um you know just drilling things down deeper I mean the ones were disposed in the deep ocean disposed whatever I I don't know why it's not just drilled down deep in the Rock that's probably a good reason for that but it seems like sort of an obvious thing to do um but uh yeah also by the way I mean there are there are skins for making nuclear reactors where you can use many of the waste products and that's I think one of the things again I don't know the details of these modular reactors I should have paid more attention but I think some of them make use of the waste products um and it's sort of a closed cycle in the end I think yeah in fact in fact one of them yes yes there's one type where you seal it up for 100 years and it just you know uses it internally uses the the products of its of its um uh of its uh nuclear reactions and so on anyway I should stop there thanks for joining me thanks for we had a bit of a range of questions today um and uh I see there were many other interesting questions left over for another time but uh thanks so much and bye for now

Channel: Wolfram

Views: 1,975

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Id: sQMYKrrPat0

Length: 90min 7sec (5407 seconds)

Published: Sat Apr 22 2023