the more i learn about entropy the more i'm convinced that simple explanation 'entropy is disorder' is very very wrong and harmful to actual understanding.
Also, 1 food "calorie" is equal to 1 kilocalorie, so each "calorie" you see on the packaging is actually 1000 calories. Not sure why they specify it that way.
Hi Phil. I apologize for my previous comment, I ended up being as insensitive as the worst trolls in my own videos. I love this channel and I am really thankful for the dedication and generosity of everybody involved, including the camera guy, the producer , editor, etc. You guys deserve better than a quick and dirty comment typed during lunch on a smartphone. I am reading James Gleick's excellent "Information: a theory, a history a flood" (after reading "Chaos") and I just read about the Maxwell's daemon and entropy and information and energy and all of that, and I was glad to watch your video in such a convenient time, and please allow me to add a few remarks about this specific video. This whole channel is very authentic and spontaneous precisely because it' so improvised and natural. I also publish tons of videos myself, and I always improvise and publish the result as-is, no editing or embellishments. Improvisation, though, comes at a risk: we may lose focus and precision, and when it happens it is very difficult not to show it. If we lose track of our thoughts our viewers will get lost too, and that's what I think it happened this time. if we take into account the expectation created by the title and the way you managed the available time, you spent so much time trying to communicate the notion of entropy that there was little time left for the concept of energy x information, which was conveyed in turbo speed. so... sorry for being unfair and superficial and mean in my first comment (which I deleted to avoid unnecessary flames), and my kudos for your inspiring work. I am not a native speaker, I am not a physicist, but you guys have been providing wonderful food for my hungry soul. best regards from Sao Paulo, Brazil.
@@Triantalex wow, my comment was posted SEVEN YEARS AGO ! you definitely have a lot of time on your hands :D anyway... I am sorry if my original comment (which I can't find anymore) was frivolous or inadequate, and I apologized for that. I am trying to be a better person everyday and I recognize that I am still far from being as rational and fair as I would like to be best regards from São Paulo, Brazil, and sorry for my broken english
I have one question, Mr.Moriarty,Entroy is a measure of how a system is Most likely to progress in time, since the probability of a group of states is larger than a specific kind of state?
Information in Mars is random and you have to do work to arrange it into knowledge of physics, and given the number of molecules, it will take some time.
Entropy measures a system's current state, the *difference* in entropy between two states is a measure of how likely the system is to progress and is correlated with how fast it will progress there.
"Phil does entropy... again." If you've not seen the earlier entropy videos with Professor Moriarty (or, indeed, any of the other videos he's done), do watch them! They are quite entertaining and also educational.
I know words, I have the best words. Nobody respects women more than me. I am the least racist person who you have ever met. Nobody lies better than me. Believe me. Sad!
Took me almost my entire undergraduate coursework before I found a teacher that taught us in discrete terms what entropy was. Scary that most professors in the sciences have no clue what entropy means; usually just a vague understanding of a single expression or character of entropy. Guy was an aeronautical adviser to the white house. I was fortunate to be placed in his class.
Sixty Symbols I know *an* answer, having a friend who did this as a science fair project. They got an average of 92 licks with a standard deviation of 12 licks. Of course the sample size was only 30.. Parents just won't buy candy for kids, even for science.
Would be nice if you broke that huge number down further at the end. It ends up being roughly 8 billion years of 1080p 60fps video if there's no fancy interframe video compression. Also it would be enough information to store the entire Internet roughly 30 million times over.
So happy to see Professor Moriarty again! Ahhh this is my favorite channel on TH-cam and I was wondering if I'd ever get another physics video from you all. People love your content!!!! Please keep the physics coming!
“We all behave like Maxwell’s demon. Organisms organize. In everyday experience lies the reason sober physicists across two centuries kept this cartoon fantasy alive. We sort the mail, build sand castles, solve jigsaw puzzles, separate wheat from chaff, rearrange chess pieces, collect stamps, alphabetize books, create symmetry, compose sonnets and sonatas, and put our rooms in order, and all this we do requires no great energy, as long as we can apply intelligence. We propagate structure (not just we humans but we who are alive). We disturb the tendency toward equilibrium. It would be absurd to attempt a thermodynamic accounting for such processes, but it is not absurd to say we are reducing entropy, piece by piece. Bit by bit. The original demon, discerning one molecules at a time, distinguishing fast from slow, and operating his little gateway, is sometimes described as “superintelligent,” but compared to a real organism it is an idiot savant. Not only do living things lessen the disorder in their environments; they are in themselves, their skeletons and their flesh, vesicles and membranes, shells and carapaces, leaves and blossoms, circulatory systems and metabolic pathways - miracles of pattern and structure. It sometimes seems as if curbing entropy is our quixotic purpose in the universe.” ― James Gleick, The Information: A History, a Theory, a Flood
I love how most physicists are always so passionate about what they do. It's really special seeing a grown man be this excited about something; passion is something people tend to lose a lot as they grow older.
Woah woah woah. Slow down. Nobody can accurately think of a full picture 1920x1080 24 bits. A thought (even in picture) is more likely a few concepts like: Phil in a theater raisin his hand with a demonic doll on the desk. Which sounds more like a few hundreads bits.
Brains are more apt to process information by discarding about 99% of it. In that sense, it's not really appropriate to just calculate the bits of an image. You only process the "important parts", the so-called "exformation", anyway. The information stream may be large, but it's cut to size like a filter. This is how we don't collapse from the information input of just living for a single second in reality.
***** I'm responding to a post. What am I not supposed to take literally? I know that 60 symbols is ballparking, but they're ballparking in the completely wrong ballpark.
The thing about Maxwell's Demon, if the barrier is frictionless it still requires energy to accelerate. Think about the electron going through a point on the plane of the barrier. Changing whether that point is passable or not requires energy. To block a particle, the barrier has to have mass or charge. In order to accelerate the mass or turn the charge on and off, you'd need energy. I suspect, considering each action only moves one particle across, that would outweight any gain.
I like watching prof. Moriarty's video's, but they always leave me with more questions than answers. As he himself states, the content of the video is hugely simplified, but imho to the point where it is just confusing... like stating that the molecule is on the left or right side of the box is one bit of information. It might be, but the amount of energy I can extract also depends on the size of the box, the speed of the mocule etc. So this doesn't make the relation between energy and a bit of information clear at all! I am more confused now about what a basic bit of information is!
But ASSUMING all those other things are known, knowing about the position (at the which side of the box -level granularity) is exactly one additional bit of information.
You have to pick which bit of information is important for measuring the mars bars into "pieces of information" that we can use to get the answer for the question. He's giving a few differently examples of how you can think about what 1 bit of information of a piece of mars bar would be.
The information content for a single particle is whether the particle is or is not inside the box. If short it's a two-state system and its entropy in "nats" is ln(2) or (in appropriate units of energy divided by temperature) k*ln2. Then you just use the equation (which is not really applicable in this case but never mind). E=TS The temperature T is proportional to the average kinetic energy per particle, so for one massive particle in one dimension it's m(v^2)/2 so that's how you get everything to fit together, for a particle transferring some momentum onto the piston when it may or may not be there.
Very nice video. Nothing new for people who studied science, but probably interesting for general public. But I cant help myself... That passion of professor Moriaty is so contagious. Must be so great to be his students. I´d wish to have such "burning" teacher when I was in university. And thank you, Brady, for longer video! :-)
It's an interesting idea to put "1 thought" as one frame of 1080p video because then you can work out how long of a HD video you get out of a given amount of energy. As it works out, one mars bar contains just about enough energy to film the time from the big bang to now in HD.
Entropy never made sense to me until I saw the equation S = K*ln(w), which I simply read off as "entropy equals some constant times a function of possible particle/energy combinations". After seeing entropy equated to the number of combinations of particle and energy units, it made a lot more sense. Hopefully this super simplified explanation helps someone lost in the comments.
Good to see Prof Moriarty is back :) Btw. "Gedanken" means nothing more than "thoughts" in german. So Gedankenexperiments is a thought-experiment, just in case someone was confused.
The key thing starts at 11:48 when Professor uses the Boltzmann constant to get the amount of energy contained in 1bit of information at room temperature. Then he calculates how many bits there are in a picture and then how much energy. Then he divides the energy in a Mars bar by the energy in the picture to get how many pictures there could be in the Mars bar.
Fantastic video! It would be so awesome to see an actual lecture by prof Moriarty! Sort of like what Stanford university does with their profs. Still i`m so damn happy to be able to get this awesome information well presented and free. What an awesome world we live in!
I am a little confused as to why it is necessary to give 'thought' energy. It isn't as if the daemon was harnessing free energy - it was just gaining the potential of using up the system's intrinsic kinetic energy. I don't see why that is a problem and why Maxwell's 2nd law of thermodynamics prohibits this from happening - agreed entropy will decrease in the container but it will increase some place else. If we consider the whole system there will be a 0 net change in entropy which is expected as it is an ideal system.
There is an article in Nature magazine 406(from 2000) by Seth Lloyd titled "Ultimate physical limits to computation", which talks about this and is exceptionally interesting, even if you ignore the math. He's also published a great deal of other papers dealing with information, entropy and basically everything Prof. Moriarty talks about here.
So am I understanding this right? The thoughts and knowledge of the demon are being used as the energy put in to get work out, even with no real physical interaction.. If so. That is freaking amazing
I feel weird understanding this, it's like Ive been shown a very blurry image and declared it to be crystal clear. I get the point of the video but I also understand I get nothing about entropy and its links to information.
This was a giant very elaborated excuse so Phil could play with a Doll, some balls and a cardbox. It is ok Phil, it is ok. :P Now seriously, great video.
Though I enjoyed the other entropy videos more, I would still like to continue exploring this subject if it's not a "dead horse" yet! These are my favorite videos as the concept itself is so mesmerizing. Please do more if you don't have any other ideas!
Just an interesting aside, I've read in multiple sources that we estimate the human brain can't process much more than about 120 bits of information per second. It seems to be a pretty well supported estimate in the psychological literature.
The partition/valve is just the thought accuracy of measurement at that moment. Concerning the demon it would know all movement/spin/trajectory/energy beforehand and can predict molecule movement. Almost like looking into the future.
Brilliant! Information and work are related precisely via a formula that describes how much work you can get out of one bit of information. Inversely does this also describe how much work you need to extract one bit of information? How does this relate to the cost of computation? IIRC Landauer showed that in principle computation can be made free by making all gates reversible and putting the computer in a heat bath. This is such a fascinating topic, please show us more!
this is the best comment section on youtube ....... usually I try to avoid the comment section but I love reading the comments here seriously I love everything about this channel -Awesome content -Inspiring professors -Amazing people in the comment section AHHHHHHHHHH SCIENCE !!!!!!!!!!!!!!
Why is it when I ask a physicist about something going the speed of light they respond with "that's not possible" but here we have the entire premise of an experiment based on friction-less, perfect surfaces that require no energy to manipulate. The demon must be involved in the system by definition and the elimination of its accounting would always seem to be an error.
they say "that's not possible" because thought experiments that involve this going faster than light or at the speed of light lead to logical contradictions, meaning they can't exist.
That doll may be Maxwell's Demon but entropy is the demon of every physics teacher and physicist out there trying to explain it to the general public. "No, shuffling a pack of cards does not increase the entropy of the pack"
Richard Feynman on Maxwell's demon: 'It turns out, if we build a finite-sized demon, that the demon himself gets so warm that he cannot see very well after a while. The simplest possible demon, as an example, would be a trap door held over the hole by a spring. A fast molecule comes through, because it is able to lift the trap door. The slow molecule cannot get through, and bounces back. But this thing is nothing but our ratchet and pawl in another form, and ultimately the mechanism will heat up. If we assume that the specific heat of the demon is not infinite, it must heat up. It has but a finite number of internal gears and wheels, so it cannot get rid of the extra heat that it gets from observing the molecules. Soon it is shaking from Brownian motion so much that it cannot tell whether it is coming or going, much less whether the molecules are coming or going, so it does not work.' : )
There was a brilliant documentary on this topic by Jim Alkilili. Forgot its name but it's something to do with information in the title of the documentary. Fascinated me ever since and uses animation to describe it rather than just a cardboard box and weird kids toy haha.
Interesting, I never took the time to dissect it in that way. I usually just think of it as 20% of my caloric intake going to my brain. I guess it's simply the difference between macro and micro economics. I was glad to see Maxwell's Demon and entropy in relation to the process though. They probably could have gone further with that, but they were trying to keep it brief.
There is no conversion between clock speed and energy. This video is about the conversion between information and energy. The proper question is "how many bits are in a cookie". A typical cookie has about 78,000 calories, which is about 300,000 joules, about 1/3 a mars bar. Use the conversion rate derived from Boltzmann's Constant, 3x10^-21 J/bit, and you get 1.08x10^26 bits. Divide by 8 to convert to bytes, 1.35^25 bytes. That is 13 yottabytes, the biggest official SI prefix. It's 13,000 zettabytes, 13,000,000 exabytes, 13,000,000,000 petabytes, or 13,000,000,000,000 terabytes, (the biggest commercially available drives when I checked to answer a similar question yesterday are 10 terabytes)
FunOrange There is nothing absurd about the title. Thoughts are information, and information is energy. It isn't intuitive, but it also isn't absurd, any more than "how many miles of tesla driving are in a head of cabbage?". That's a thing you can calculate.
I imagine we simplify images a lot. I don't remember each individual pixel. It becomes more like a vector image. And we take shortcuts as well like if there is something repeating we just remember how many times it repeats, we forget details etc so there is some compression too.
Really though the "energy" of a Mars bar is actually more like the mass of the bar times c^2 if you were able to convert the entire bar into pure energy. So if you took half a Mars bar made of matter and half a Mars bar made of anti-matter (a Sram bar?) and stuck them together you'd release that much pure energy which you could then compare to the energy of a "thought" to see how many thoughts are contained in a Mars bar.
How does this demon relate to the osmosis phenomena and filtration techniques? Regarding the energy consumed by a thought or information bit, it's more easy to get a free lunch by the demon, than to get the right bit of information by oneself.
I'm a little confused on the whole getting free work out of moving the piston on its own. Dr. Moriarty says that moving the piston when it doesn't have to move the particle is workless because it's frictionless, but isn't just the act of moving it adding work into the system? The only way moving the piston could be workless is if the piston was massless, however, if that is the case, then the particle moving the piston with its entropy would be workless too because of the piston having no mass.
Very fascinating! However, as a neuroscientist, the metaphorical use of a "thought" confounds me immensely. Let's assume the thought is truthfully represented in your brain with the resolution of a 1080p still picture (it's not, but let's), you would still need continuous energy input to keep the representation active. *So how does time factor into this?* Is the associated energy just for one "frame", if you will, of thought processing (and there is no such thing)?
Software is like entropy. It is difficult to grasp, weighs nothing, and obeys the second law of thermodynamics; i.e. it always increases. ~Norman Ralph Augustine
I think that many people are going to mix up 'energy associated with one though' and 'energy it took to generate that though' . The latter takes considerably more energy because we are inefficient organic beings. We should switch to silicon.
It's not making free energy, that's the thing. The energy that the demon needs for the information needs to come from somewhere. The crucial result of this thought experiment is that you cannot decrease the entropy of a system without increasing entropy somewhere else. Also, "demon" is a classical way of talking about something that is making decisions and doing things in the background. If you run a *nix computer (OSx, linux, android, iOS), there are thousands of daemons running in the background, serving up your screen, counting the time, talking with the network, waiting for inputs, etc. This example describes Maxwell's Demon, there's also Decartes' Demon, which you would probably identify with the machines in "The Matrix", there's Laplace's Demon, a thought experiment that disproves classical mechanics by pointing out that a demon that knows the position and speed of every particle in the universe knows the full past, present, and future. Morton's Demon is another word for Confirmation bias, the idea is there's a little devil that sits between your senses and your mind and only lets in information that already agrees with your beliefs.
It's interesting when you list the demons like that because all of those represent something that we are unable to do to create the conditions for a thought experiment except for Morton's Demon which is just there to simplify a conceptual layer of the thought process that actually exists. (a filter that favors information that fits into one's existing world view)
Even with no friction, how does moving an object (the piston or the wall) do zero work? I don't see the problem, and I bet a lot of other people don't either.
For as little as we know about the brain we know it takes electro-chemical energy to operate, we also know that of all the calories you eat your brain uses the largest single portion: ~300 calories of that mars bar would be used in the brain just to keep it operating in this example I'd estimate. So would that not contribute to the entropy of the greater system because even the demon in this thought experiment has to have an actively functioning, thought producing brain in order to operate the frictionless partition. I feel like the ratio would much, much larger, probably even within the laws of thermodynamics when you take into account the computational energy required to track, assess, and react to a set of individual molecules.
I've got a bit of an issue with how he calculates the size of a thought. When my brain sees a picture, it doesn't register the exact color value of every pixel. Take his picture for example. His skin was blue. Given a little time I can probably remember a few more details about his skin (like how it was more cyan than blue), but for the most part my brain probably only stored a small fraction of the exact "bits" that the video used to display it. Our brains don't remember every little detail of everything they sense. They don't even come close to that. Even autistic savants who can draw exact portraits of things they've seen don't remember _every_ detail, and that skill is often to the exclusion of most other higher-order brain functionality. So having the idea that "thoughts must be equal in size to their sensory content" as a starting point gives us some problems. Of course, I know he was just using the number of pixels as a neutral and easy-to-comprehend starting point, and I think this idea is on the right track. It just needs major refinement if it's to be applied to a real-world brain having actual thoughts.
This video was some real...
food for thought.
heh, I see what you did there
This needs to be the top comment. We need to make this the top comment.
Idon't know how. Maybe if I had a Mars bar I could.
sweet comment.
k
He keeps trying to describe entropy, but the descriptions just keep getting more random.
i see what you did there XD
Entropy is a difficult thing to explain. Alle easy pictures tend to lead to false assumtions. It's a real subtle topic.
the more i learn about entropy the more i'm convinced that simple explanation 'entropy is disorder' is very very wrong and harmful to actual understanding.
And now you can't unsee it, Ahmed!
Next someone will discribe recursion?
"If we work in PROPER units, which is Joules, and not the calorie nonsense."
*hear eV crying in the distance*
Also, 1 food "calorie" is equal to 1 kilocalorie, so each "calorie" you see on the packaging is actually 1000 calories. Not sure why they specify it that way.
yeah, that one really cracked me up.
You can tell he's passionate about what he does.
Or just insane and smart.
+Calvin K thats the same
ikr, i love this guy.
Can't wait to start lectures with this champion in September :)
Not at the level of the Kleine bottle guy though.
Hi Phil. I apologize for my previous comment, I ended up being as insensitive as the worst trolls in my own videos. I love this channel and I am really thankful for the dedication and generosity of everybody involved, including the camera guy, the producer , editor, etc. You guys deserve better than a quick and dirty comment typed during lunch on a smartphone.
I am reading James Gleick's excellent "Information: a theory, a history a flood" (after reading "Chaos") and I just read about the Maxwell's daemon and entropy and information and energy and all of that, and I was glad to watch your video in such a convenient time, and please allow me to add a few remarks about this specific video.
This whole channel is very authentic and spontaneous precisely because it' so improvised and natural. I also publish tons of videos myself, and I always improvise and publish the result as-is, no editing or embellishments. Improvisation, though, comes at a risk: we may lose focus and precision, and when it happens it is very difficult not to show it. If we lose track of our thoughts our viewers will get lost too, and that's what I think it happened this time.
if we take into account the expectation created by the title and the way you managed the available time, you spent so much time trying to communicate the notion of entropy that there was little time left for the concept of energy x information, which was conveyed in turbo speed.
so... sorry for being unfair and superficial and mean in my first comment (which I deleted to avoid unnecessary flames), and my kudos for your inspiring work. I am not a native speaker, I am not a physicist, but you guys have been providing wonderful food for my hungry soul.
best regards from Sao Paulo, Brazil.
Wow, respect! Realising your original comment was lacking nuance and coming back on it takes a lot of courage.
Wow, disrespect!
@@Triantalex wow, my comment was posted SEVEN YEARS AGO ! you definitely have a lot of time on your hands :D
anyway... I am sorry if my original comment (which I can't find anymore) was frivolous or inadequate, and I apologized for that. I am trying to be a better person everyday and I recognize that I am still far from being as rational and fair as I would like to be
best regards from São Paulo, Brazil, and sorry for my broken english
So if I understand it right, I just got to eat Mars bar and I get my PhD in Physics?
I have one question, Mr.Moriarty,Entroy is a measure of how a system is Most likely to progress in time, since the probability of a group of states is larger than a specific kind of state?
Information in Mars is random and you have to do work to arrange it into knowledge of physics, and given the number of molecules, it will take some time.
Entropy measures a system's current state, the *difference* in entropy between two states is a measure of how likely the system is to progress and is correlated with how fast it will progress there.
Since it won't work because information in Mars bar is random, would it work if I ate a brain of someone with a PhD ?
ILYES
Yes, but you have a 50% chance of zombism.
"Phil does entropy... again." If you've not seen the earlier entropy videos with Professor Moriarty (or, indeed, any of the other videos he's done), do watch them! They are quite entertaining and also educational.
Phil Moriarty is an idiot
I know words, I have the best words. Nobody respects women more than me. I am the least racist person who you have ever met. Nobody lies better than me. Believe me. Sad!
Took me almost my entire undergraduate coursework before I found a teacher that taught us in discrete terms what entropy was. Scary that most professors in the sciences have no clue what entropy means; usually just a vague understanding of a single expression or character of entropy.
Guy was an aeronautical adviser to the white house. I was fortunate to be placed in his class.
Had to double check the title of this video.
Now, tell us how many licks it takes to get to the center of a tootsie pop.
+Gareth Dean joking aside, do you know the answer to that?
+Sixty Symbols Should be a topic for Periodic Videos, I suppose. "Assuming every lick removes a layer one molecule thick off the tootsie bar,..."
My six year old daughter actually kept track and it was 96 licks.
+Sixty Symbols Around 1000+ licks to a center. One less worrying thought, one attogram (pun intended), less on your mind ;)
Sixty Symbols
I know *an* answer, having a friend who did this as a science fair project. They got an average of 92 licks with a standard deviation of 12 licks.
Of course the sample size was only 30.. Parents just won't buy candy for kids, even for science.
Prof Moriarty really should have his own channel....He is fantastic. The passion he has is contagious.
He has his own channel actually.
He does, search for: Philip Moriarty
Mind Blown! Thanks
Google, and you shall find...
Phil Moriarty is an idiot
I understood about nothing in this video, but man, can Phil talk and generate enthusiasm!
Always delighted to see Phil talking. Hes so passionate and moreover his Videos always get very long, what I really like.
Would be nice if you broke that huge number down further at the end. It ends up being roughly 8 billion years of 1080p 60fps video if there's no fancy interframe video compression. Also it would be enough information to store the entire Internet roughly 30 million times over.
+DrMrProfJacob cool
If only thinking was a better way to lose weight.
+liltonyabc Unfortunately I think it wouldn't make much of a difference in today's society! lol
did he just assume the gender of the demon?
I love professor Moriarty!!!
My new favourite quote, "go on, let me write one equation. just one."
So happy to see Professor Moriarty again! Ahhh this is my favorite channel on TH-cam and I was wondering if I'd ever get another physics video from you all. People love your content!!!! Please keep the physics coming!
really love this channel
+Cullen Gilfillan thank you for watching - we probably wouldn't get to keep making videos if no-one ever watched. :)
+Cullen Gilfillan thank you for watching - we probably wouldn't get to keep making videos if no-one ever watched. :)
Speaking of replying, you guys did it twice xD
8:56
He really caresses that demon alot. Not sure if sweet or creepy.
You get a much larger number of thoughts using E=mc^2 for the mass of a mars bar
Phil is the best part of Sixty Symbols
this is one of the most fascinating videos i've seen on youtube in a long time, even on this channel.
+aksen303 thanks for taking the time to watch it
Idk what is it with this information-entropy topic that i find it enormously fascinating
“We all behave like Maxwell’s demon. Organisms organize. In everyday
experience lies the reason sober physicists across two centuries kept
this cartoon fantasy alive. We sort the mail, build sand castles, solve
jigsaw puzzles, separate wheat from chaff, rearrange chess pieces,
collect stamps, alphabetize books, create symmetry, compose sonnets and
sonatas, and put our rooms in order, and all this we do requires no
great energy, as long as we can apply intelligence. We propagate
structure (not just we humans but we who are alive). We disturb the
tendency toward equilibrium. It would be absurd to attempt a
thermodynamic accounting for such processes, but it is not absurd to say
we are reducing entropy, piece by piece. Bit by bit. The original
demon, discerning one molecules at a time, distinguishing fast from
slow, and operating his little gateway, is sometimes described as
“superintelligent,” but compared to a real organism it is an idiot
savant. Not only do living things lessen the disorder in their
environments; they are in themselves, their skeletons and their flesh,
vesicles and membranes, shells and carapaces, leaves and blossoms,
circulatory systems and metabolic pathways - miracles of pattern and
structure. It sometimes seems as if curbing entropy is our quixotic
purpose in the universe.”
―
James Gleick,
The Information: A History, a Theory, a Flood
I love how most physicists are always so passionate about what they do. It's really special seeing a grown man be this excited about something; passion is something people tend to lose a lot as they grow older.
A Sixty Symbols video a day helps you work, rest and play
One of my favorite videos of all time
Woah woah woah. Slow down. Nobody can accurately think of a full picture 1920x1080 24 bits. A thought (even in picture) is more likely a few concepts like: Phil in a theater raisin his hand with a demonic doll on the desk. Which sounds more like a few hundreads bits.
its an aproximation since we dont realy know how the brain thinks
gytux0258
I know. And even tho, that would only make the number of thought in a Mars bar even higher.
I know how the brain thinks...
_(short pause)_
Just like that.
Brains are more apt to process information by discarding about 99% of it. In that sense, it's not really appropriate to just calculate the bits of an image. You only process the "important parts", the so-called "exformation", anyway. The information stream may be large, but it's cut to size like a filter. This is how we don't collapse from the information input of just living for a single second in reality.
*****
I'm responding to a post. What am I not supposed to take literally?
I know that 60 symbols is ballparking, but they're ballparking in the completely wrong ballpark.
The thing about Maxwell's Demon, if the barrier is frictionless it still requires energy to accelerate.
Think about the electron going through a point on the plane of the barrier. Changing whether that point is passable or not requires energy.
To block a particle, the barrier has to have mass or charge. In order to accelerate the mass or turn the charge on and off, you'd need energy.
I suspect, considering each action only moves one particle across, that would outweight any gain.
I like watching prof. Moriarty's video's, but they always leave me with more questions than answers. As he himself states, the content of the video is hugely simplified, but imho to the point where it is just confusing... like stating that the molecule is on the left or right side of the box is one bit of information. It might be, but the amount of energy I can extract also depends on the size of the box, the speed of the mocule etc. So this doesn't make the relation between energy and a bit of information clear at all! I am more confused now about what a basic bit of information is!
But ASSUMING all those other things are known, knowing about the position (at the which side of the box -level granularity) is exactly one additional bit of information.
You have to pick which bit of information is important for measuring the mars bars into "pieces of information" that we can use to get the answer for the question. He's giving a few differently examples of how you can think about what 1 bit of information of a piece of mars bar would be.
The information content for a single particle is whether the particle is or is not inside the box. If short it's a two-state system and its entropy in "nats" is ln(2) or (in appropriate units of energy divided by temperature) k*ln2. Then you just use the equation (which is not really applicable in this case but never mind).
E=TS
The temperature T is proportional to the average kinetic energy per particle, so for one massive particle in one dimension it's m(v^2)/2 so that's how you get everything to fit together, for a particle transferring some momentum onto the piston when it may or may not be there.
There's something strangely satisfying about watching Prof Moriarty illustrate his points with a goth doll. :)
I LOVE IT WHEN HE SHOWS US THE MATH EQUATIONS AND STUFF.
MUCH LOVE SIXTY SYMBOLS
Love the energy of Professor Moriarty! :) I could listen for hours.
Very nice video. Nothing new for people who studied science, but probably interesting for general public.
But I cant help myself... That passion of professor Moriaty is so contagious. Must be so great to be his students. I´d wish to have such "burning" teacher when I was in university.
And thank you, Brady, for longer video! :-)
It's an interesting idea to put "1 thought" as one frame of 1080p video because then you can work out how long of a HD video you get out of a given amount of energy. As it works out, one mars bar contains just about enough energy to film the time from the big bang to now in HD.
Entropy never made sense to me until I saw the equation S = K*ln(w), which I simply read off as "entropy equals some constant times a function of possible particle/energy combinations". After seeing entropy equated to the number of combinations of particle and energy units, it made a lot more sense. Hopefully this super simplified explanation helps someone lost in the comments.
Good to see Prof Moriarty is back :)
Btw. "Gedanken" means nothing more than "thoughts" in german.
So Gedankenexperiments is a thought-experiment, just in case someone was confused.
"Go on... let me right one equation on the board, just one" xD
The key thing starts at 11:48 when Professor uses the Boltzmann constant to get the amount of energy contained in 1bit of information at room temperature. Then he calculates how many bits there are in a picture and then how much energy. Then he divides the energy in a Mars bar by the energy in the picture to get how many pictures there could be in the Mars bar.
Fantastic video! It would be so awesome to see an actual lecture by prof Moriarty! Sort of like what Stanford university does with their profs. Still i`m so damn happy to be able to get this awesome information well presented and free. What an awesome world we live in!
more of prof. Moriarty please :) I can watch and listen to him for hours...
I was starting to miss Prof. Moriarty, he used to appear in many videos a couple of years ago.
I am a little confused as to why it is necessary to give 'thought' energy. It isn't as if the daemon was harnessing free energy - it was just gaining the potential of using up the system's intrinsic kinetic energy. I don't see why that is a problem and why Maxwell's 2nd law of thermodynamics prohibits this from happening - agreed entropy will decrease in the container but it will increase some place else. If we consider the whole system there will be a 0 net change in entropy which is expected as it is an ideal system.
5:09 Brady's best line ever
You know, the flaw in this thought experiment is the use of a Mars bar instead of Snickers.
I love this term "Nutritional Energy" in regards to Mars Bars
Prof. Moriarty is one my favorite guys, ever.
There is an article in Nature magazine 406(from 2000) by Seth Lloyd titled "Ultimate physical limits to computation", which talks about this and is exceptionally interesting, even if you ignore the math. He's also published a great deal of other papers dealing with information, entropy and basically everything Prof. Moriarty talks about here.
Now I'm really thinking of applying to Nottingham for physics because of Prof. Moriarty.
Somebody needs to give Phil his own TV show.
How many mars bars will it take moriarty to realise that winters is a joke?
You could use a sentence to describe a thought. "Light is a wave" would take just 15 bytes or 120 bits.
Love watchin' good teachers teach..
So am I understanding this right? The thoughts and knowledge of the demon are being used as the energy put in to get work out, even with no real physical interaction.. If so. That is freaking amazing
I feel weird understanding this, it's like Ive been shown a very blurry image and declared it to be crystal clear. I get the point of the video but I also understand I get nothing about entropy and its links to information.
This was a giant very elaborated excuse so Phil could play with a Doll, some balls and a cardbox. It is ok Phil, it is ok. :P
Now seriously, great video.
That demon doll is just beautiful!
Though I enjoyed the other entropy videos more, I would still like to continue exploring this subject if it's not a "dead horse" yet!
These are my favorite videos as the concept itself is so mesmerizing. Please do more if you don't have any other ideas!
12:50 "Got me Mars bar for lunch" Sounds really healthy, haha
Just an interesting aside, I've read in multiple sources that we estimate the human brain can't process much more than about 120 bits of information per second. It seems to be a pretty well supported estimate in the psychological literature.
RIP Phil
I, for one, support videos of Phil playing with his dollies.
An average looking man with a cool accent passionately talking about science. Nothing could arouse me more.
Scenario:
You have Prof Moriarty and Tadashi and James Grime on a sinking boat and can only save one.
Who do you save and why?
I like it when my brain hurts after watching these, means I'm learning. Thank you for these videos.
The partition/valve is just the thought accuracy of measurement at that moment. Concerning the demon it would know all movement/spin/trajectory/energy beforehand and can predict molecule movement. Almost like looking into the future.
Brilliant! Information and work are related precisely via a formula that describes how much work you can get out of one bit of information. Inversely does this also describe how much work you need to extract one bit of information?
How does this relate to the cost of computation? IIRC Landauer showed that in principle computation can be made free by making all gates reversible and putting the computer in a heat bath.
This is such a fascinating topic, please show us more!
This whole issue of information changing the conditions of the system reminds me of the Monty Hall Problem and why it's always so counter-intuitive.
How many Thunderf00ts are in a Sixty Symbols video?
this is the best comment section on youtube ....... usually I try to avoid the comment section but I love reading the comments here
seriously I love everything about this channel
-Awesome content
-Inspiring professors
-Amazing people in the comment section
AHHHHHHHHHH SCIENCE !!!!!!!!!!!!!!
Why is it when I ask a physicist about something going the speed of light they respond with "that's not possible" but here we have the entire premise of an experiment based on friction-less, perfect surfaces that require no energy to manipulate. The demon must be involved in the system by definition and the elimination of its accounting would always seem to be an error.
they say "that's not possible" because thought experiments that involve this going faster than light or at the speed of light lead to logical contradictions, meaning they can't exist.
As if demon's don't.
Jason Hord this particular demon does not lead to contradictions, though the solution isn't that obvious.
That doll may be Maxwell's Demon but entropy is the demon of every physics teacher and physicist out there trying to explain it to the general public. "No, shuffling a pack of cards does not increase the entropy of the pack"
Richard Feynman on Maxwell's demon:
'It turns out, if we build a finite-sized demon, that the demon himself gets so warm that he cannot see very well after a while. The simplest possible demon, as an example, would be a trap door held over the hole by a spring. A fast molecule comes through, because it is able to lift the trap door. The slow molecule cannot get through, and bounces back. But this thing is nothing but our ratchet and pawl in another form, and ultimately the mechanism will heat up. If we assume that the specific heat of the demon is not infinite, it must heat up. It has but a finite number of internal gears and wheels, so it cannot get rid of the extra heat that it gets from observing the molecules. Soon it is shaking from Brownian motion so much that it cannot tell whether it is coming or going, much less whether the molecules are coming or going, so it does not work.' : )
Lecture 46, from the Feynman lecture series.
There was a brilliant documentary on this topic by Jim Alkilili. Forgot its name but it's something to do with information in the title of the documentary. Fascinated me ever since and uses animation to describe it rather than just a cardboard box and weird kids toy haha.
Interesting, I never took the time to dissect it in that way. I usually just think of it as 20% of my caloric intake going to my brain. I guess it's simply the difference between macro and micro economics. I was glad to see Maxwell's Demon and entropy in relation to the process though. They probably could have gone further with that, but they were trying to keep it brief.
The link to Moriartys blog says it has been deleted?
Do you have a valid link?
So if someone offers me a penny for my thoughts, am I still being overpaid?
+Ouija ha ha
Nice title.
What's the processing speed of a cookie?
There is no conversion between clock speed and energy. This video is about the conversion between information and energy. The proper question is "how many bits are in a cookie".
A typical cookie has about 78,000 calories, which is about 300,000 joules, about 1/3 a mars bar. Use the conversion rate derived from Boltzmann's Constant, 3x10^-21 J/bit, and you get 1.08x10^26 bits.
Divide by 8 to convert to bytes, 1.35^25 bytes. That is 13 yottabytes, the biggest official SI prefix. It's 13,000 zettabytes, 13,000,000 exabytes, 13,000,000,000 petabytes, or 13,000,000,000,000 terabytes, (the biggest commercially available drives when I checked to answer a similar question yesterday are 10 terabytes)
icedragon769 If you couldn't tell I was mocking the absurdity of the title.
FunOrange There is nothing absurd about the title. Thoughts are information, and information is energy. It isn't intuitive, but it also isn't absurd, any more than "how many miles of tesla driving are in a head of cabbage?". That's a thing you can calculate.
icedragon769 By my definition that's absurd.
You actually have to put in energy to keep the gate closed. Because particles like the fast ones "want" to get out.
Why do I chuckle every time he shakes that demon doll at me?
A feeling is just a thought - and a thought is just a bit of information.
But how does the piston being frictionless = free energy? You still have to give it energy to move. It's not gonna move itself.
I imagine we simplify images a lot. I don't remember each individual pixel. It becomes more like a vector image. And we take shortcuts as well like if there is something repeating we just remember how many times it repeats, we forget details etc so there is some compression too.
Really though the "energy" of a Mars bar is actually more like the mass of the bar times c^2 if you were able to convert the entire bar into pure energy. So if you took half a Mars bar made of matter and half a Mars bar made of anti-matter (a Sram bar?) and stuck them together you'd release that much pure energy which you could then compare to the energy of a "thought" to see how many thoughts are contained in a Mars bar.
How does this demon relate to the osmosis phenomena and filtration techniques? Regarding the energy consumed by a thought or information bit, it's more easy to get a free lunch by the demon, than to get the right bit of information by oneself.
I'm a little confused on the whole getting free work out of moving the piston on its own. Dr. Moriarty says that moving the piston when it doesn't have to move the particle is workless because it's frictionless, but isn't just the act of moving it adding work into the system? The only way moving the piston could be workless is if the piston was massless, however, if that is the case, then the particle moving the piston with its entropy would be workless too because of the piston having no mass.
This video is a giant add for Mars Bars!
Very fascinating! However, as a neuroscientist, the metaphorical use of a "thought" confounds me immensely. Let's assume the thought is truthfully represented in your brain with the resolution of a 1080p still picture (it's not, but let's), you would still need continuous energy input to keep the representation active. *So how does time factor into this?* Is the associated energy just for one "frame", if you will, of thought processing (and there is no such thing)?
Software
is like entropy. It is difficult to grasp, weighs nothing, and obeys
the second law of thermodynamics; i.e. it always increases.
~Norman Ralph Augustine
I think that many people are going to mix up 'energy associated with one though' and 'energy it took to generate that though' . The latter takes considerably more energy because we are inefficient organic beings. We should switch to silicon.
If the demon is making free energy....then we can solve a lot of problems...then why is it still a demon?
Bc it wants your soul in exchange
+StrikePlaysGames Then never mind, I'll just burn more coal, it's better that way.
Because it's a daimōn:
en.wikipedia.org/wiki/Daemon_(classical_mythology)
en.wikipedia.org/wiki/Demon_(thought_experiment)
It's not making free energy, that's the thing. The energy that the demon needs for the information needs to come from somewhere. The crucial result of this thought experiment is that you cannot decrease the entropy of a system without increasing entropy somewhere else.
Also, "demon" is a classical way of talking about something that is making decisions and doing things in the background. If you run a *nix computer (OSx, linux, android, iOS), there are thousands of daemons running in the background, serving up your screen, counting the time, talking with the network, waiting for inputs, etc.
This example describes Maxwell's Demon, there's also Decartes' Demon, which you would probably identify with the machines in "The Matrix", there's Laplace's Demon, a thought experiment that disproves classical mechanics by pointing out that a demon that knows the position and speed of every particle in the universe knows the full past, present, and future. Morton's Demon is another word for Confirmation bias, the idea is there's a little devil that sits between your senses and your mind and only lets in information that already agrees with your beliefs.
It's interesting when you list the demons like that because all of those represent something that we are unable to do to create the conditions for a thought experiment except for Morton's Demon which is just there to simplify a conceptual layer of the thought process that actually exists. (a filter that favors information that fits into one's existing world view)
Why isn't lifting the barrier up and down introducing work into the system?
Even with no friction, how does moving an object (the piston or the wall) do zero work? I don't see the problem, and I bet a lot of other people don't either.
I'm going to have to eat approximately 7 million mars bars to digest this video.
I figured it out guys. The universe is expanding because we are storing more and more information. Gimme my Nobel prize.
I'm eating a mars bar while watching this. I feel more powerful now.
The content of this video is WAY more interesting than the title suggests. 😂
For as little as we know about the brain we know it takes electro-chemical energy to operate, we also know that of all the calories you eat your brain uses the largest single portion: ~300 calories of that mars bar would be used in the brain just to keep it operating in this example I'd estimate. So would that not contribute to the entropy of the greater system because even the demon in this thought experiment has to have an actively functioning, thought producing brain in order to operate the frictionless partition. I feel like the ratio would much, much larger, probably even within the laws of thermodynamics when you take into account the computational energy required to track, assess, and react to a set of individual molecules.
But, we never got to why this demon doesn't break thermodynamics.
5:16 and further, did he really say "Gedankenexperiements"? Like half German and half English in a single word?
I've got a bit of an issue with how he calculates the size of a thought. When my brain sees a picture, it doesn't register the exact color value of every pixel. Take his picture for example. His skin was blue. Given a little time I can probably remember a few more details about his skin (like how it was more cyan than blue), but for the most part my brain probably only stored a small fraction of the exact "bits" that the video used to display it. Our brains don't remember every little detail of everything they sense. They don't even come close to that. Even autistic savants who can draw exact portraits of things they've seen don't remember _every_ detail, and that skill is often to the exclusion of most other higher-order brain functionality. So having the idea that "thoughts must be equal in size to their sensory content" as a starting point gives us some problems.
Of course, I know he was just using the number of pixels as a neutral and easy-to-comprehend starting point, and I think this idea is on the right track. It just needs major refinement if it's to be applied to a real-world brain having actual thoughts.
Honestly I prefer to think of it as the energy associated with the picture itself, i.e if it was an actual picture on a screen, not a thought.
He made a pretty big point about how simplified this explanation is. I'm pretty sure he realizes that. You are doing what he told you not to do :P