I like the way Baierlein (Thermal Physics p.44) describes it in my textbook: "You may, however, sometimes hear entropy characterized as 'a measure of disorder.' [...] The words 'order' and 'disorder' are colloquial and qualitative; nonetheless they describe a distinction that we are likely to recognize in concrete situations, such as the state of someone's room. [...] Imagine a bedroom with the usual complement of shoes, socks, and T-shirts. Suppose, further, that the room is one that we intuitively characterize as 'orderly.' Then, if we see one black dress shoe of a pair, we know -- without looking -- that the other shoe is right next to it. If we see one clean T-shirt, then the others are in a stack just below it. There are strong correlations between the shoes in a pair or the T-shirts on the dresser. Those correlations limit severely the ways in which shoes and T-shirts can be distributed in the room, and so the objects exhibit a small multiplicity and a low entropy. Now take the other extreme, a bedroom that we immediately recognize as 'disorderly.' If we see one jogger, we have no idea where the other jogger is. Under the dresser? Behind the bed? Lost in the pile of dirty T-shirts? And, for that matter, what about the T-shirts? If we see one on the dresser, the next clean one may be on the desk or in the easy chair. Correlations are absent, and the objects enjoy a large multiplicity of ways in which they may find themselves distributed around the room. It is indeed a situation of high entropy. There is usually nothing wrong with referring to entropy as 'a measure of disorder.' The phrase, however, doesn't take one very far. To gain precision and something quantitative, one needs to connect 'disorder' with 'absence or correlations' and then with multiplicity. It is multiplicity that has sufficient precision to be calculated and to serve as the basis for a physical theory." TL;DR. Order Strong correlation Small multiplicity Disorder Absence of correlation Large multiplicity
How does order come out of entropy in this analogy? The messy guy tosses his shoes around and sometimes the two black shoes wind up next to each other by chance?
@@ceruchi2084 Imagine that the shoes have some sort of adhesive between them so that they stay together once they end up next to each other once. This is, I think, how the forming of crystal structures (i. e. chemical bonding) works: the electrons in the free moving atoms have more energy than those in the bond, so if two atoms interact (i. e. happen to be next to each other), the chemical bond is created while the electrons give off that energy as heat. That's also what happens when some thing burns.
Your best videos come from Phil Moriarty, even when you don't fully understand what he's talking about he's still really interesting to listen to. You can tell he's very passionate about his work. Amusing extra footage as well.
The number of ways you can rearrange the particles of something and still end up with the same structure. For example, a sand castle has lower entropy than a sand pile.
@@markymark863 So what you're trying to say is that the no. of ways sand particles can be arranged so it forms castle structure is less than no. of ways in which sand particles can be arranged so that it forms a pile?
Entropy: Can be low or high, low would be comparable to a rubik's cube solved. High, is the cube scrambled. What do you need to solve it? An intelligent mind who in a smart way introduces energy to the system to solve it; G-D.
Entropy is the observable tendency of matter to assume the most stable state based on statistical energy distribution. Usually, this manifests itself as "disorder" especially when we talk about gases or liquids. The key thing is to get people to stop thinking of entropy as a force that "does something" (as too many professors teach in undergraduate thermodynamics), but instead as an observation or measurement that can inform us about other aspects of whatever we are examining.
In other words, entropy is a process, not a substance, the way heat is a process and not a substance. Could people be making the mistake of thinking about entropy as something similar to phlogiston? That could explain a lot.
EXACTLY. I am sooo tired of people talking about entropy as if it is a force that is exerted on the universe by something. Entropy is just the way we describe the natural tendencies of matter to distribute itself - as you say. Entropy isn't a "real" thing.
hobowithashotgun48 "Entropy is the observable tendency of matter to assume the most stable state based on statistical energy distribution." Hobo (funny coincidence), is that yours? I've googled for that exact quote but could not find it. This is the most succinct and clearest explanation I have heard. Is physics your profession?
mountainhobo Yes, it's my own explanation. I formulated it while teaching chemistry prior to starting grad-school. There is nothing better for improving your own understanding of a concept than trying to explain it to someone else. My background is in biochemistry, which I actually think is better for understanding entropy than physics: In physics you focus on the more abstract mathematical definition, which may not fully convey the nature of the concept. In biochemistry on the other hand you cover very practical applications of entropy such as predicting protein folding based on molecular interactions. Who knew that hobos are so into science?
Entropy is a measurement of dispersion of energy in a system, an increase of entropy means that becomes more difficult to extract energy in a system, the appearance of order or disorder is irrelevant to entropy by example if you order all the atoms, particles and matter in the universe equidistant to each order, gravity cannot work, so entropy will be at its maximum but the universe will look very orderly.
stevo728822 No, it's almost exactly the opposite. A highly predictable system, like a crystal, generally has very low entropy. The OP is basically just wrong.
Great video, charismatic, engaging and concise delivery. Nice back story with the frustration over previous work and explaining flaws with entropy descriptions. Nice touch with the citations too. More of this please.
How many different ways have you found it defined? Yes the standard book definitions are pretty consistent, but when you try to derive an *operational definition* from the ways it's often explained or used, the definitions seem wildly contradictory.
I’m seldom able to personally attach very much feeling or muster very much enthusiasm to any subject. I really like the way Professor Moriarty is able to convey his enthusiasm and sincerity about these subjects. It gives me so much value when I watch these videos
I'm a computer science major, but damn does your content make me interested to learn more than the required physics and chemistry. I really enjoy the quick education type of content on youtube, I can't get enough of it. I would love if you put an interesting math problem in the info section related to each video.
I am so happy to see another video on entropy. This is one of the most difficult concepts for most people, due to all the reasons he went over (the oversimplification of entropy as order versus disorder is probably the biggest culprit). Thank you Phil and Brady!
Phil, thanks for persuading Brady to pursue this. As an Armchair Physics fan, I've been researching terms like "Does Life = Negative Entropy" precisely because of the Entropy Confusion that you explain here. I've looked into Shannon's Entropy with regard to the number of bits of information and followed it through to Lenny Suskind's lectures on Black Hole Entropy and it all seems at odds with the laws of thermodynamics and Brian Cox's sandcastle analogy. Sure, there's a grey area for for popular science and there's a definite area for career scientists, but there is a middle ground for folk who want more than BBC science, hence why we turn to you guys - please keep pushing it the direction you're going as it is great to have people who really know their stuff impart their knowledge at a level beyond "6 cans of stella and a chicken tikka" level - there is a thirst out there for grown up science and I love the fact you are willing to give us that - well done you!
It takes a lot to begin wrapping your head around it. Studying statistical mechanics and learning to implement Molecular Dynamics starting from statistical mechanics principles will do the trick. I realize this comment is six years old... so, were you able to eventually gain a better understanding?
THANK YOU! The order-disorder description of entropy has made me uncomfortable for so many years, but I keep hearing people defend it. I understand how it's a useful tool to casually explain to someone unfamiliar with physics what entropy is -- especially because entropy is so complex -- but while it's a handy intro to the concept, people are often given only that explanation, and in that situation I've seen it leave too many people with really bad notions of entropy that they use to convince themselves of very wrong ideas. I'm really glad you made this video. You have a chance to get a lot of vision on this issue with people who wouldn't otherwise find out about it.
now, here's a small problem, the entropy IS going up, but NOT in the crystal, it goes up in the entire system , which in our case is the universe if you would consider a smaller system, like an isolated room, with some ions inside, eventually the ions will clump together and form the low-entropy crystal, but that will ALWAYS release heat, and the heat will drive the entropy of the room higher, even if there's a vacuum in the room, the total entropy will still be higher because now the disorder of the energy inside the room is higher than any possible disorder the initial ions might of had
This video really captures the essence of what science is all about: modeling the real world, trying to understand how things are related, and continually revising your understanding to better fit with the evidence. Things may be complicated and difficult to explain, but that just makes them all the more interesting.
One way I think of it is like dropping a ball. Yes, there are thousands of directions the ball could go in, but it's always going to go straight down because gravity is acting on it. You always have to take into effect inputs of energy, because that wildly distorts the probabilities of one outcome over another.
Declan Siewert Elaborating on Banana's answer, it is the flag of Gondor in Tolkien's Middle Earth, showing the white tree of Gondor combined with the seven stars of the House of Elendil and, though not seen in fakjbf's profile picture, crowned with the crown of the King. It is the symbol both of Gondor's line of great kings and of the kingdom as a whole.
Isn't the concept of order an intrinsically human thing? I mean an arrangement of particles that can look disordered to us might have an underlying order that isn't obvious to a human observer.
Actually, there is a concrete definition of order, but some systems that are technically ordered may not seem ordered to humans. This is not a scientific definition of order, but it is a definition consistent with the common explanations of entropy and the common intuition of what order is. Order describes a set of conditions for which there are relatively few ways to satisfy. For example, if were comparing sandcastles and sand dunes, there only a few ways to arrange grains of sand in a fashion that would seem to me like a sand castle in comparison to the many, many ways to arrange sand so that it fits my definition of a dune. Therefore, sandcastles are more ordered than dunes. Similarly, there are only a few ways to arrange a deck of cards (in fact, only 24) such that all cards of the same suit are together, and the value of the cards are ascending (within each suit), but there are many ways to arrange the cards in no particular order i.e. a random shuffle (about 8 x 10^67 ways). Therefore a shuffled deck is _less_ ordered.
You are touching on the philosophy of maths and science here. My view is that all these things we talk about in science are properties we have observed in physical systems, so they more or less exist independently of human thought, in so much as they correctly describe physical reality. You could argue that mathematics and logic have this property, Maths because it is derived from measuring and counting and other ways of observing physical reality, thinking about it and seeing if an idea we have come up with is somehow useful. In science useful means it both explains something about reality and also predicts something new in reality, but in mathematics we are looser in our definition of utility, and say anything that is interesting and somehow logically consistent as useful. Even logic can be seen in this way, seen as the codification of those approaches to reasoning which has proved successful in the past. I.E. those which have reached conclusions which have eventually been proven correct. People, even scientists and mathematicians, are often very surprised when some seemingly unrelated obscure branch of mathematics finds sudden application to some field of scientific inquiry. Often it almost seems like the mathematics was purpose built for that branch of science, even though it was invented independently. But should it really be a surprise, given that mathematics started off as measuring and counting of the real world and that it developed by applying reasoning and imagination to these foundations, and then checking that what results makes some sort of logical sense? Why should we be surprised then when we invent something that later on seems perfect to describe some aspect of physical reality?
Sideeq Mohammad "Entropy is a measure of the number of microscopic configurations Ω that correspond to a thermodynamic system in a state specified by certain macroscopic variables." en.wikipedia.org/wiki/Entropy
@@KWGTech How does that work if we have an infinite number cards? With an infinite amount of cards every combo could be ordered but it would be beyond our scope of perception would it not?
Start again from scratch! Make a THIRD video. Do not apologize for, or refer to, the first pair of videos. Take a deep breath, figure out what the hell entropy is, and then explain it to us well.
I worked in the nuclear industry as a radiation control technician and learned alot about the nuclear world as it relates to radiation and atoms. But listening to yall I realize just how much I love science. Even though im not a scientist, my degree is in operations and project management, I have learned so much from your videos. Please keep up the awsome work you are doing it is wonderful.
Brady you made a video for PeriodicVideos a few years ago called "Becoming a Chemist - Viewer Questions". It would be interesting to see a similar video for SixtySymbols.
I have to say I'm finally very happy about that explanation, professor Moriarty. That's what I'm always saying: one cannot understand entropy without the Gibbs ensemble, because it's all about the number of microscopic representations of a given macro-state. I would add to that, that if ergodic hypothesis is satisfied, so the system is exploring every micro-state with equal probability making the time averages equal to the ensemble averages, the second law of thermodynamics becomes a trivial statement. It simply means that the system will evolve to a more likely state, i.e. having more microscopic representations. I think you explained very well what the entropy is exactly, formula and all. Thanks.
As someone who just spent something like 6 or 7 weeks of P-Chem this whole video, and Brady's questions in the video just make me smile because of how complicated and interrelated all of the thermodynamic values are.
I've been introduced to chemistry in high school and in college. So, I have a general understanding of entropy and enthalpy. I was interested in the scenario where entropy resulted in a more ordered system. I would be happy to sit and listen to a full lecture, and / or future videos on this topic.
This video clarified the subject a lot to me. Thanks a lot Prof. for being so interested in finding the best way to explain these concepts to us, I really appreciate it.
Entropy is a measure of the number of ways a system can be in a state. For example, suppose I have 5 coins. Here's the number of ways for me to have X heads. X | ways 0 | 1 1 | 5 2 | 10 3 | 10 4 | 5 5 | 1 What this means is that if you were to continuously flip the coins, you would very often see 2 or 3 heads (disordered), and very rarely 0 or 5 (ordered). Therefore, the disordered states have higher entropy.
SillyPutty125 I am not trying use fancy quotes here. I am just saying Simplicity is harder to understand then complexity. I can much easier understand any number of instructions on how to for example close a door but having the "simplest" explanation which you could argue for example be Math makes absolutely no sense to me and would require me to learn allot to even have a basic understanding.
me and many others use the term rejuvenation with the body to stop entropy...giving the system as a whole what it needs to function correctly, while removing "obstruction" so you dont have continued entropy in weaker areas of the body ....very neat to watch this discussion and see all the ways we can figure out what happens on this rock floating thru space....
I just want to say the coverage of the various topics, though brief, is informative and intriguing. These video shorts have piqued my interest and have been the impetus for a number of follow-up searches (by me, of course) into the myriad of subjects covered. Thank you, to all contributors, for sharing and I certainly am looking forward to the many left to watch. Keep up the fantastic work!
So...entropy is basically the tendency of closed systems to form into more likely arrangements and not the tendency of closed systems to become more disordered?
8 років тому+2
It's the statistics of saying which end state is most likely given the total number of combinations. If that states are about molecules moving around. Whichever type of state has the most options will end up being the most likely outcome.
Thank you so much for providing the videos and website. 60 Symbols really makes a difference for those of us on the outside looking in. Very accessible.
This is what I find hard to grasp. If heat promotes entropy, how is it that our current universe, which is colder, has a higher entropy than, say, the universe when it was a few microseconds old (which was hotter)? There should be more ice crystals in the universe now than a few seconds after the big bang. If the universe is in fact a closed system, that's expanding thus making heat be less "potent" how is it that entropy increases within it?
What do you mean by "heat promotes entropy"? Remember that heat is a type of energy. You can add an amount of heat dQ to a system that has a temperature T. The second law of thermodynamics then says that the entropy of that system increases by an amount dS that is greater than or equal to dQ/T. Also, the entropy of a closed system never decreases. It can stay constant though, if the processes in the system are reversible. Doing thermodynamics in an expanding universe complicates things a bit... I recall from a cosmology course that the entropy scales at the same rate as the volume of the universe, but I do not remember and/or understand it well enough to explain it. Maybe someone else can :)
seigeengine Probably, that's why I said I find it hard to grasp in the original post. Because I'm confused. Are you able to elaborate an enlightening answer, otherwise you don't look smarter than I. ^_^
Istvan Kleijn Ok, but how does that answer the original question of a cooler expanded universe having an increased entropy in relation to a super heated smaller universe? I mean, if as you said, and I quote: "The importance of entropy depends on the temperature, when the temperature is twice as high, the entropy term is twice as important".
I still find entropy a very hard concept to grasp for a simple mind like mine, fuzzy analogies definitely don't help. But in the bright side, as I keep trying to wrap my head around it, I get a good excuse to revisit Professor Moriarty's videos, which is always lovely!
how about a series of videos? Entropy is a pretty interesting topic and, as shown in this video, seems to be pretty complex too. A few more videos into that might clear things up a bit for all of us
Brian Cox did a wonderful job explaining entropy in his series Wonders of the Universe. He explained by making a sand castle in the Namib desert. There is always going to be a lower number of possible configurations where the sand retains the shape of the castle, rather than the sand just being scattered in dunes.
Thanks for making this video, I've been aware for a while that describing entropy as a measure of order is very misleading. Describing it as the number of ways you can create a specific state is a much better way. Glad this video was made.
Hmm I can see the guy is passionate about th topic. The message however is a little difuse, maybe making a video with a little more preparation and focus on the message could be considered.
Thank you Professor Moriarty for following up on this theme and unpacking the complicated feature called entropy. Thanks Brady, you ask a lot of good questions as well for the layman like me. Another thoroughly enjoyed Haran video!
Why do your headphones always come out of your pocket tangled? Entropy! Shoving them in there and walking around in effect randomizes their position. Since there are far more ways to tangle a string than there are to keep it perfectly coiled, the odds are your headphones will come out tangled.
What's more: once it becomes slightly tangled, the movements that would untangle it are less likely to occur than the movements that either keep it in the same tangled state or make it worse. Thus, over time, statistically speaking, the headphones will reach ever increasing tangled-ness (assuming you have an infinite long headphone cord; in real life there would be a limit).
I just read the paper. Perhaps a better analogy would be that soldiers at a parade represent a low entropy situation, whereas people in a piazza (imagine people walking across the piazza in all directions at different speed) represent a high entropy situation. What about that?
forgot to add I also absolutely love the sixty symbols videos (all of Brady's channels are awesome but I'd totally have sex with physics if I could so of course sixty symbols is my favourite!)
The description of Entropy being described as the number of ways a system can be arranged is really what made this click for me, what used to throw me is that it's said the universe is constantly moving towards entropy (which is regularly used as a synonym for disorder) but in the heat death of the universe, all energy will be uniform, those 2 statements used to seem highly contradictory to me but I think I see what's meant now. Hopefully I have a correct understanding of entropy now, even if it is a minor one, thanks for the re-do of the video.
I prefer the strictly statistical-mechanical interpretation of entropy, as you showed at 7:07 : it is the logarithmically scaled form of the number of microstates of a system. That is, the number of ways a system can be arranged. "Order," however, is almost entirely a perceived (not actual) value. For example, most people tend to perceive a glass of water as being more "ordered" than a glass of crushed ice, yet the glass of water has higher entropy. We are unable to perceive the information stored in the motion of the particles (liquid water as opposed to ice), so it does not fit into our concept of "ordered" or "disordered" system, and therefore fails when describing the entropy of a system.
I feel like the video cuts off right when we're getting close to having a sufficient picture of actual entropy leading to situations like spontaneous crystalization or apparent 'order' from 'disorder'.
I hate how he keeps having to shorten what he's saying, I wish he could just have all the time he wanted to explain this concept as much as the average person could understand.
+Katie Bennie This or just the *amount of possibilities the particles of a system can be arranged*. The best example I heard was with a glass of beer: When beer is fresh from the tap, it has it's whitecap. Now a whitecap seems more disordered than the beer fluid because the fluid is nice, clear and smooth while the cap is a mess of bubbles. But if entropy always increases, why do I need to put energy into the system of beer (blowing into it for instance) to create new bubbles but when I just leave it alone, the cap vanishes. Because actually in the fluid the entropy is higher than in the cap, because the molecules in the cap are limited to the walls of small bubbles which gives the fluid particles less ways to be arranged than in the open fluid. When the cap vanishes over time, the entropy of the beer increases as the beer molecules sink into the open fluid and are free to float and arrange with the other molecules in the glass.
That simulation form 6:15 looks a lot similar to the distribution of matter/energy in the universe just at a very increased timescale. First almost uniform distribution, then it clumps into groups connected into threads and lastly an almost empty space.
I am so glad that this video was made! I have been arguing for not using disorder to describe entropy for a very long time! Thank! (I might even have made a post in the past one of these videos about it)
I enjoyed the S=k log W where W stands for (number of) ways. In short one could say Entropy is a macrosopic property that quantifies at thermal equilibrium the number of ways energy can be distributed over the entities in a homogeneous system.
I like this bloke - he gets [k]narked quite easily and the more of his videos you watch, the more things you discover upset him.This is thermodynamics for you - even the vaguest understanding of just the tiniest slice of the subject can leave you quick to ire and grossly upset your otherwise gentle condition.
I did wonder why there wasn't much mention of the energy part in the last video. I remember reading an excellent description that made perfect sense to me--you can tidy your house and put everything where it belongs, thus putting the objects in a low-entropy state, but the energy you took to do it, the biological energy and heat energy and mechanical energy and so on of you moving and putting those things in place, that still creates an increase in the overall entropy. You're burning energy in your muscles, exhaling CO2, radiating heat, and so on--that creates more entropy than what you took away by putting everything away.
I think the best way to explain entropy, is by first explaining the concept of the Gibbs Free Energy, and what it means about a system then introduce dG = dH + TdS. Because then dS can be related to its dependence on the temperature. The throw in how with the temperature and the energy flow in the system things either adopt a ordered or disordered state. I don't know but I will look at those papers for sure.. great topic this one
The equation for Gibbs free energy is actually a simple derivation of the second law.The total entropy change of the universe is given by dG/T. dS in this case merely refers to the internal entropy change of the system, You really need to understand the second law and have a basic understanding of entropy before you can understand the meaning of the Gibbs function.
Brady, may i suggest prof. Moriarty make 2 or 3 videos on entropy one for beginners, one for people who took physic after high school and one for experts like his colleges in non physics areas like professional researchers and scientists. i can see that he wants to talk about more advanced topics but doesn't want to confuse everyone. Love the Video!
The crystal example is a bad example for proofing your point because you did not mention the "order" of the water molecules. There are several water mol that solvate the ions. Since that is from view of the water mol much more ordered than being "free",so again the "order" of the system decreases when crystallisation happens through the much higher gain of "disorder" on the "water side".
? So by “making the box smaller” entropy decreases? And to make the box smaller one needs to decrease the amount of energy needed to do a quantity of work. Is that it?
Ways... that is a great way to visualize it. I think I will keep this in mind next time I get that blank look when I use the word "entropy" in the real world. Seems like a much better way to illustrate it to people who haven't heard of it before. Good vid :)
Well, the problem with order is its subjectivity. What is order? Are the atoms of two different elements ordered when they are in a crystal shape or when they are divided in two seperate volumes?
I don't understand why people find it so hard to understand entropy. The second law of thermodynamics implies that the total entropy of a closed system always increases. It doesn't say anything about the entropy content of individual parts of such a system, who are free to rid themselves of any amount of entropy they wish, provided there is a greater increase of entropy somewhere else in that system. What is so hard to understand about that?
Naive question: if the entropy term is multiplied with the temperature, does that mean crystallization is "allowed" to produce an ordered structure because it gives of enough heat so the entropy of the system as a whole goes up? i.e. crystallization, e.g. when a slab of steel solidifies in a mill, gives off so much heat because the structure it produces is so ordered as opposed to a merely very very hot liquid cooling down to a much cooler liquid. Or did I misunderstand something?
Soooooo they're effectively replicating high pressures and/ or temperatures? Thank you for this. I've been stewing on this one for a while. The concepts involved make way more sense to me now. I think the biggest issue with trying to describe entropy is with or need to simplify and boil things down to their most basic components, but for the rules of entropy one has to consider the entire universe and all the time it has experienced.
So is entropy related to the number of different spatial positions a molecule can occupy? In the paper from Lambert it is mentioned only that the energetic micro-states are important, I think (so molecule velocities, vibration frequencies etc.?). So which one is it?
Is entropy directly proportional to the number of ways a system can be arranged. So if entropy increases it doesn't mean that we can't have an ordered system, the chance of this decreases?
I find the videos on entropy to be very interesting but to complex for the format of video that you guys keep releasing. Would it be possible to do a series of videos that explain the base models all the way up to the full complexity of entropy and disorder?
The cange from amporphed to crystaline in a structure releases heat. Heat has high entropy, so when a system becomes ordered, entropy in universe increases.
For anyone who didn't take chemistry: the *enthalpy* change, expressed by Hess's law, states that the change in energy (measured as temperature in the classroom in joules and written as ΔH) needed to change one substance to another is constant, regardless of the number of reactions that have happened.
this video gave me a new perspective of what we believe to be order or disorder... perhaps order is merely a matter of perspective, lets say a tesseract in our dimension is perceived as disordered because we lack the understanding to perceive it any other way. so whats to say entropy is to endlessly increase. - this is a very simple comment about something i dont really understand just trying to gain knowledge.
This really bothered me in chemistry class in high school. My teacher adamantly and stubbornly objected when I insisted that her analogy of entropy and disorder was monumentally misleading, and frankly quite outdated. I've recently graduated, but if I ever see her again I will most certainly shove this in her face. Maybe this crudely simplified video will finally make her understand.
I've never had a problem getting my head round entropy and I love some of these explanations. I heard one over on Veritasium where he likened a low entropic system to a single continuous low information and low entropy and then as you add 1s and 0s you add information and increase entropy, until finally the system has to much information to make sense of (white noise) and thus you have the entropic limit. I personally like the script analogy, but taken a step further, you have a billion page script in order and then you blow it up, but each letter of each page zips of in all different directions, if you slow the explosion down so it takes a few billion years, then the letters will fly apart and form new words, sentences and stories, until finally they all float to the floor and are at rest and at the highest entropic state. Probably completely misleading analogies, but they work for me :)
Interesting that the data equivalent entropy now seems to be the same as the physics "the number of ways" possible permutations? Was that always the case?
Confusion about entropy always increases
As the chef said when asked to hurry up with the food for a particular table: "dis-order or dat-order?".
tmjcbs I love your comment.
+tmjcbs or it doesn't change (isentropic process)
I wish UA-cam mobile would let me upvote this
I concur
I like the way Baierlein (Thermal Physics p.44) describes it in my textbook:
"You may, however, sometimes hear entropy characterized as 'a measure of disorder.'
[...] The words 'order' and 'disorder' are colloquial and qualitative; nonetheless they describe a distinction that we are likely to recognize in concrete situations, such as the state of someone's room.
[...] Imagine a bedroom with the usual complement of shoes, socks, and T-shirts. Suppose, further, that the room is one that we intuitively characterize as 'orderly.' Then, if we see one black dress shoe of a pair, we know -- without looking -- that the other shoe is right next to it. If we see one clean T-shirt, then the others are in a stack just below it. There are strong correlations between the shoes in a pair or the T-shirts on the dresser. Those correlations limit severely the ways in which shoes and T-shirts can be distributed in the room, and so the objects exhibit a small multiplicity and a low entropy.
Now take the other extreme, a bedroom that we immediately recognize as 'disorderly.' If we see one jogger, we have no idea where the other jogger is. Under the dresser? Behind the bed? Lost in the pile of dirty T-shirts? And, for that matter, what about the T-shirts? If we see one on the dresser, the next clean one may be on the desk or in the easy chair. Correlations are absent, and the objects enjoy a large multiplicity of ways in which they may find themselves distributed around the room. It is indeed a situation of high entropy.
There is usually nothing wrong with referring to entropy as 'a measure of disorder.' The phrase, however, doesn't take one very far. To gain precision and something quantitative, one needs to connect 'disorder' with 'absence or correlations' and then with multiplicity. It is multiplicity that has sufficient precision to be calculated and to serve as the basis for a physical theory."
TL;DR.
Order Strong correlation Small multiplicity
Disorder Absence of correlation Large multiplicity
this really helped ...... thanks :)
How does order come out of entropy in this analogy? The messy guy tosses his shoes around and sometimes the two black shoes wind up next to each other by chance?
@@ceruchi2084 Imagine that the shoes have some sort of adhesive between them so that they stay together once they end up next to each other once.
This is, I think, how the forming of crystal structures (i. e. chemical bonding) works: the electrons in the free moving atoms have more energy than those in the bond, so if two atoms interact (i. e. happen to be next to each other), the chemical bond is created while the electrons give off that energy as heat.
That's also what happens when some thing burns.
@@xCorvus7x The guy has OCD and allways place the items in the same way.
@@TextiX887 Basically, yes.
And there's a little extra bit: ua-cam.com/video/maWvwuYR4VA/v-deo.html
Thank you brady for uploading the extra bit so quickly. I felt that the discussion would not have ended at that with you being there and all.
Bravo for revisiting an earlier video!
The very essence of science is revision, so Bravo!
Your best videos come from Phil Moriarty, even when you don't fully understand what he's talking about he's still really interesting to listen to. You can tell he's very passionate about his work.
Amusing extra footage as well.
That extra bit is totally worth it! Awesome.
88Cardey
Also, he's called Professor Moriarty, how cool is that?
The only way this is helpful is that it makes clear I have no idea what entropy is.
I will!
The number of ways you can rearrange the particles of something and still end up with the same structure. For example, a sand castle has lower entropy than a sand pile.
It's disorder, pay attention!
@@markymark863 So what you're trying to say is that the no. of ways sand particles can be arranged so it forms castle structure is less than no. of ways in which sand particles can be arranged so that it forms a pile?
Entropy: Can be low or high, low would be comparable to a rubik's cube solved. High, is the cube scrambled. What do you need to solve it? An intelligent mind who in a smart way introduces energy to the system to solve it; G-D.
Entropy is the observable tendency of matter to assume the most stable state based on statistical energy distribution. Usually, this manifests itself as "disorder" especially when we talk about gases or liquids. The key thing is to get people to stop thinking of entropy as a force that "does something" (as too many professors teach in undergraduate thermodynamics), but instead as an observation or measurement that can inform us about other aspects of whatever we are examining.
In other words, entropy is a process, not a substance, the way heat is a process and not a substance. Could people be making the mistake of thinking about entropy as something similar to phlogiston? That could explain a lot.
EXACTLY.
I am sooo tired of people talking about entropy as if it is a force that is exerted on the universe by something. Entropy is just the way we describe the natural tendencies of matter to distribute itself - as you say.
Entropy isn't a "real" thing.
hobowithashotgun48 "Entropy is the observable tendency of matter to assume the most stable state based on statistical energy distribution."
Hobo (funny coincidence), is that yours? I've googled for that exact quote but could not find it. This is the most succinct and clearest explanation I have heard. Is physics your profession?
Best comment. I think this is my favorite comment at least of this week, if not of this year. Very well done explanation.
mountainhobo Yes, it's my own explanation. I formulated it while teaching chemistry prior to starting grad-school. There is nothing better for improving your own understanding of a concept than trying to explain it to someone else.
My background is in biochemistry, which I actually think is better for understanding entropy than physics: In physics you focus on the more abstract mathematical definition, which may not fully convey the nature of the concept. In biochemistry on the other hand you cover very practical applications of entropy such as predicting protein folding based on molecular interactions. Who knew that hobos are so into science?
Entropy is a measurement of dispersion of energy in a system, an increase of entropy means that becomes more difficult to extract energy in a system, the appearance of order or disorder is irrelevant to entropy by example if you order all the atoms, particles and matter in the universe equidistant to each order, gravity cannot work, so entropy will be at its maximum but the universe will look very orderly.
+elchippe This is a very elegant example.
So, a diamond appears very orderly but difficult to get energy from it.
diamonds are actually flamable
So increasing entropy is increasing predictability?
stevo728822 No, it's almost exactly the opposite. A highly predictable system, like a crystal, generally has very low entropy. The OP is basically just wrong.
Entropy isn't what it used to be :(
Entropy isnt' waht it usde et:b (o
I see what you did there.
That's right... because it's always increasing! (ha HA!)
***** You dont see what he did there, its already gone.
i can't see what he did there
Great video, charismatic, engaging and concise delivery. Nice back story with the frustration over previous work and explaining flaws with entropy descriptions. Nice touch with the citations too. More of this please.
Entropy is one of my favorite topics in Physics, and I haven't watched the previous videos on it. But very much enjoyed this one.
How many different ways have you found it defined? Yes the standard book definitions are pretty consistent, but when you try to derive an *operational definition* from the ways it's often explained or used, the definitions seem wildly contradictory.
I’m seldom able to personally attach very much feeling or muster very much enthusiasm to any subject. I really like the way Professor Moriarty is able to convey his enthusiasm and sincerity about these subjects. It gives me so much value when I watch these videos
I'm a computer science major, but damn does your content make me interested to learn more than the required physics and chemistry. I really enjoy the quick education type of content on youtube, I can't get enough of it.
I would love if you put an interesting math problem in the info section related to each video.
I am so happy to see another video on entropy. This is one of the most difficult concepts for most people, due to all the reasons he went over (the oversimplification of entropy as order versus disorder is probably the biggest culprit). Thank you Phil and Brady!
I think Brady has one of the best jobs in the world.
Phil, thanks for persuading Brady to pursue this. As an Armchair Physics fan, I've been researching terms like "Does Life = Negative Entropy" precisely because of the Entropy Confusion that you explain here. I've looked into Shannon's Entropy with regard to the number of bits of information and followed it through to Lenny Suskind's lectures on Black Hole Entropy and it all seems at odds with the laws of thermodynamics and Brian Cox's sandcastle analogy. Sure, there's a grey area for for popular science and there's a definite area for career scientists, but there is a middle ground for folk who want more than BBC science, hence why we turn to you guys - please keep pushing it the direction you're going as it is great to have people who really know their stuff impart their knowledge at a level beyond "6 cans of stella and a chicken tikka" level - there is a thirst out there for grown up science and I love the fact you are willing to give us that - well done you!
Anyone worse off after watching this video? Or is it just me?
Remember Socrates
"worse off"? Nah I feel fine. 🤷♂️
This video clarified a lot for me.
It takes a lot to begin wrapping your head around it. Studying statistical mechanics and learning to implement Molecular Dynamics starting from statistical mechanics principles will do the trick.
I realize this comment is six years old... so, were you able to eventually gain a better understanding?
Just you.
THANK YOU! The order-disorder description of entropy has made me uncomfortable for so many years, but I keep hearing people defend it. I understand how it's a useful tool to casually explain to someone unfamiliar with physics what entropy is -- especially because entropy is so complex -- but while it's a handy intro to the concept, people are often given only that explanation, and in that situation I've seen it leave too many people with really bad notions of entropy that they use to convince themselves of very wrong ideas. I'm really glad you made this video. You have a chance to get a lot of vision on this issue with people who wouldn't otherwise find out about it.
now, here's a small problem, the entropy IS going up, but NOT in the crystal, it goes up in the entire system , which in our case is the universe
if you would consider a smaller system, like an isolated room, with some ions inside, eventually the ions will clump together and form the low-entropy crystal, but that will ALWAYS release heat, and the heat will drive the entropy of the room higher, even if there's a vacuum in the room, the total entropy will still be higher because now the disorder of the energy inside the room is higher than any possible disorder the initial ions might of had
This video really captures the essence of what science is all about: modeling the real world, trying to understand how things are related, and continually revising your understanding to better fit with the evidence. Things may be complicated and difficult to explain, but that just makes them all the more interesting.
One way I think of it is like dropping a ball. Yes, there are thousands of directions the ball could go in, but it's always going to go straight down because gravity is acting on it. You always have to take into effect inputs of energy, because that wildly distorts the probabilities of one outcome over another.
What does your profile picture mean?
Declan Siewert Minas tirith/White tree of Gondor
Declan Siewert Elaborating on Banana's answer, it is the flag of Gondor in Tolkien's Middle Earth, showing the white tree of Gondor combined with the seven stars of the House of Elendil and, though not seen in fakjbf's profile picture, crowned with the crown of the King. It is the symbol both of Gondor's line of great kings and of the kingdom as a whole.
The Ainur could decrease entropy. True story.
You're like the first person on the internet to clear up this confusion, thank you.
Isn't the concept of order an intrinsically human thing? I mean an arrangement of particles that can look disordered to us might have an underlying order that isn't obvious to a human observer.
Actually, there is a concrete definition of order, but some systems that are technically ordered may not seem ordered to humans.
This is not a scientific definition of order, but it is a definition consistent with the common explanations of entropy and the common intuition of what order is.
Order describes a set of conditions for which there are relatively few ways to satisfy.
For example, if were comparing sandcastles and sand dunes, there only a few ways to arrange grains of sand in a fashion that would seem to me like a sand castle in comparison to the many, many ways to arrange sand so that it fits my definition of a dune. Therefore, sandcastles are more ordered than dunes.
Similarly, there are only a few ways to arrange a deck of cards (in fact, only 24) such that all cards of the same suit are together, and the value of the cards are ascending (within each suit), but there are many ways to arrange the cards in no particular order i.e. a random shuffle (about 8 x 10^67 ways). Therefore a shuffled deck is _less_ ordered.
You are touching on the philosophy of maths and science here. My view is that all these things we talk about in science are properties we have observed in physical systems, so they more or less exist independently of human thought, in so much as they correctly describe physical reality.
You could argue that mathematics and logic have this property, Maths because it is derived from measuring and counting and other ways of observing physical reality, thinking about it and seeing if an idea we have come up with is somehow useful.
In science useful means it both explains something about reality and also predicts something new in reality, but in mathematics we are looser in our definition of utility, and say anything that is interesting and somehow logically consistent as useful.
Even logic can be seen in this way, seen as the codification of those approaches to reasoning which has proved successful in the past. I.E. those which have reached conclusions which have eventually been proven correct.
People, even scientists and mathematicians, are often very surprised when some seemingly unrelated obscure branch of mathematics finds sudden application to some field of scientific inquiry. Often it almost seems like the mathematics was purpose built for that branch of science, even though it was invented independently.
But should it really be a surprise, given that mathematics started off as measuring and counting of the real world and that it developed by applying reasoning and imagination to these foundations, and then checking that what results makes some sort of logical sense? Why should we be surprised then when we invent something that later on seems perfect to describe some aspect of physical reality?
Watts the concrete definition?
Sideeq Mohammad "Entropy is a measure of the number of microscopic configurations Ω that correspond to a thermodynamic system in a state specified by certain macroscopic variables." en.wikipedia.org/wiki/Entropy
@@KWGTech How does that work if we have an infinite number cards? With an infinite amount of cards every combo could be ordered but it would be beyond our scope of perception would it not?
I love how Phil just gets up and struts around in his excitement xD Brady's camera is just all over the room
Start again from scratch! Make a THIRD video. Do not apologize for, or refer to, the first pair of videos. Take a deep breath, figure out what the hell entropy is, and then explain it to us well.
This video made me cry. I have finally understood entropy. Thank you, professor
i think im more confused then ever
That means you understand it better than you did before
I worked in the nuclear industry as a radiation control technician and learned alot about the nuclear world as it relates to radiation and atoms. But listening to yall I realize just how much I love science. Even though im not a scientist, my degree is in operations and project management, I have learned so much from your videos. Please keep up the awsome work you are doing it is wonderful.
Brady you made a video for PeriodicVideos a few years ago called "Becoming a Chemist - Viewer Questions". It would be interesting to see a similar video for SixtySymbols.
I have to say I'm finally very happy about that explanation, professor Moriarty. That's what I'm always saying: one cannot understand entropy without the Gibbs ensemble, because it's all about the number of microscopic representations of a given macro-state. I would add to that, that if ergodic hypothesis is satisfied, so the system is exploring every micro-state with equal probability making the time averages equal to the ensemble averages, the second law of thermodynamics becomes a trivial statement. It simply means that the system will evolve to a more likely state, i.e. having more microscopic representations.
I think you explained very well what the entropy is exactly, formula and all. Thanks.
continue to fight entropy every day gentlemen! i'm 100% behind you!
As someone who just spent something like 6 or 7 weeks of P-Chem this whole video, and Brady's questions in the video just make me smile because of how complicated and interrelated all of the thermodynamic values are.
Love this guy! Great respect for his passion for science and explanation.
I've been introduced to chemistry in high school and in college. So, I have a general understanding of entropy and enthalpy. I was interested in the scenario where entropy resulted in a more ordered system. I would be happy to sit and listen to a full lecture, and / or future videos on this topic.
Yes! Finally a video saying entropy is not disorder
This video clarified the subject a lot to me. Thanks a lot Prof. for being so interested in finding the best way to explain these concepts to us, I really appreciate it.
So what is entropy _really_? Apparently, the answer is "it's complicated."
Simplicity is a lie.
Entropy is a measure of the number of ways a system can be in a state.
For example, suppose I have 5 coins. Here's the number of ways for me to have X heads.
X | ways
0 | 1
1 | 5
2 | 10
3 | 10
4 | 5
5 | 1
What this means is that if you were to continuously flip the coins, you would very often see 2 or 3 heads (disordered), and very rarely 0 or 5 (ordered). Therefore, the disordered states have higher entropy.
Simplicity is harder to understand then complexity.
*****
I think you mean truth is stranger than fiction.
SillyPutty125
I am not trying use fancy quotes here. I am just saying Simplicity is harder to understand then complexity. I can much easier understand any number of instructions on how to for example close a door but having the "simplest" explanation which you could argue for example be Math makes absolutely no sense to me and would require me to learn allot to even have a basic understanding.
me and many others use the term rejuvenation with the body to stop entropy...giving the system as a whole what it needs to function correctly, while removing "obstruction" so you dont have continued entropy in weaker areas of the body
....very neat to watch this discussion and see all the ways we can figure out what happens on this rock floating thru space....
'This is from a kid's crystal growing kit'. Unless it's in my hands, and then it becomes an adult's crystal growing kit. :)
I just want to say the coverage of the various topics, though brief, is informative and intriguing. These video shorts have piqued my interest and have been the impetus for a number of follow-up searches (by me, of course) into the myriad of subjects covered.
Thank you, to all contributors, for sharing and I certainly am looking forward to the many left to watch. Keep up the fantastic work!
So...entropy is basically the tendency of closed systems to form into more likely arrangements and not the tendency of closed systems to become more disordered?
It's the statistics of saying which end state is most likely given the total number of combinations.
If that states are about molecules moving around. Whichever type of state has the most options will end up being the most likely outcome.
Thank you so much for providing the videos and website. 60 Symbols really makes a difference for those of us on the outside looking in. Very accessible.
This is what I find hard to grasp. If heat promotes entropy, how is it that our current universe, which is colder, has a higher entropy than, say, the universe when it was a few microseconds old (which was hotter)? There should be more ice crystals in the universe now than a few seconds after the big bang. If the universe is in fact a closed system, that's expanding thus making heat be less "potent" how is it that entropy increases within it?
What do you mean by "heat promotes entropy"? Remember that heat is a type of energy. You can add an amount of heat dQ to a system that has a temperature T. The second law of thermodynamics then says that the entropy of that system increases by an amount dS that is greater than or equal to dQ/T.
Also, the entropy of a closed system never decreases. It can stay constant though, if the processes in the system are reversible.
Doing thermodynamics in an expanding universe complicates things a bit... I recall from a cosmology course that the entropy scales at the same rate as the volume of the universe, but I do not remember and/or understand it well enough to explain it. Maybe someone else can :)
Damian Reloaded Yeah, I'm pretty sure what you just said didn't make sense.
seigeengine Probably, that's why I said I find it hard to grasp in the original post. Because I'm confused. Are you able to elaborate an enlightening answer, otherwise you don't look smarter than I. ^_^
seigeengine Just because in the video Prof. Moriarty mentioned thermodynamics and heat as playing a key role in the whole concept of entropy?
Istvan Kleijn Ok, but how does that answer the original question of a cooler expanded universe having an increased entropy in relation to a super heated smaller universe? I mean, if as you said, and I quote: "The importance of entropy depends on the temperature, when the temperature is twice as high, the entropy term is twice as important".
I still find entropy a very hard concept to grasp for a simple mind like mine, fuzzy analogies definitely don't help.
But in the bright side, as I keep trying to wrap my head around it, I get a good excuse to revisit Professor Moriarty's videos, which is always lovely!
how about a series of videos? Entropy is a pretty interesting topic and, as shown in this video, seems to be pretty complex too. A few more videos into that might clear things up a bit for all of us
Brian Cox did a wonderful job explaining entropy in his series Wonders of the Universe. He explained by making a sand castle in the Namib desert. There is always going to be a lower number of possible configurations where the sand retains the shape of the castle, rather than the sand just being scattered in dunes.
this guy loves what he does. always energetic
It would help if he knew what he is taking about!!!
Thanks for making this video, I've been aware for a while that describing entropy as a measure of order is very misleading. Describing it as the number of ways you can create a specific state is a much better way. Glad this video was made.
Hmm I can see the guy is passionate about th topic. The message however is a little difuse, maybe making a video with a little more preparation and focus on the message could be considered.
Thank you Professor Moriarty for following up on this theme and unpacking the complicated feature called entropy. Thanks Brady, you ask a lot of good questions as well for the layman like me. Another thoroughly enjoyed Haran video!
Why do your headphones always come out of your pocket tangled? Entropy!
Shoving them in there and walking around in effect randomizes their position. Since there are far more ways to tangle a string than there are to keep it perfectly coiled, the odds are your headphones will come out tangled.
What's more: once it becomes slightly tangled, the movements that would untangle it are less likely to occur than the movements that either keep it in the same tangled state or make it worse. Thus, over time, statistically speaking, the headphones will reach ever increasing tangled-ness (assuming you have an infinite long headphone cord; in real life there would be a limit).
My headphones go in my pocket neat and come out neat, evolution;)
AltainiaInfinity That's how rubber bands work ;-) The polymer chains get tangled and thus shrink in size. Entropy is pulling rubber bands together.
I just read the paper. Perhaps a better analogy would be that soldiers at a parade represent a low entropy situation, whereas people in a piazza (imagine people walking across the piazza in all directions at different speed) represent a high entropy situation. What about that?
I think the vid's title is appropriate - my brain system is closed and in a high state of confusion... time to do some reading on this.
forgot to add I also absolutely love the sixty symbols videos (all of Brady's channels are awesome but I'd totally have sex with physics if I could so of course sixty symbols is my favourite!)
The description of Entropy being described as the number of ways a system can be arranged is really what made this click for me, what used to throw me is that it's said the universe is constantly moving towards entropy (which is regularly used as a synonym for disorder) but in the heat death of the universe, all energy will be uniform, those 2 statements used to seem highly contradictory to me but I think I see what's meant now.
Hopefully I have a correct understanding of entropy now, even if it is a minor one, thanks for the re-do of the video.
I'd love to say I now understand more about entropy than I did before watching the video but the explanation here appears insufficient to me.
***** Not insufficient for a detailed and comprehensive understanding, insufficient to learn anything new at all. Which was kind of disappointing.
I prefer the strictly statistical-mechanical interpretation of entropy, as you showed at 7:07 : it is the logarithmically scaled form of the number of microstates of a system. That is, the number of ways a system can be arranged. "Order," however, is almost entirely a perceived (not actual) value.
For example, most people tend to perceive a glass of water as being more "ordered" than a glass of crushed ice, yet the glass of water has higher entropy. We are unable to perceive the information stored in the motion of the particles (liquid water as opposed to ice), so it does not fit into our concept of "ordered" or "disordered" system, and therefore fails when describing the entropy of a system.
I'm betting that someone is going to turn this into a religious discussion.
Yeah it's annoying. You just know someone's gonna go: "this is proof God exists, only God could do something like that"
I give it 6.67 seconds give or take.
You just did haha.
this is proof God exists, only God could do something like that
yes, you just did. Otherwise this channel usually better in that regard
I feel like the video cuts off right when we're getting close to having a sufficient picture of actual entropy leading to situations like spontaneous crystalization or apparent 'order' from 'disorder'.
I love this man!
Bana kimyayı bu adam anlatsın yeni element bile bulurum
dont flame please
You love this rude arrogant individual? Really?
I've missed videos with Phil! Like him the most
"AAAAAAAAAAH" - Me after trying to understand this video
Is it possible to read the article by Daan Frenkel online, the one that Prof Moriarty shows at 4:02?
Just google "Entropy-driven phase transitions frenkel pdf".
Derp. To make it worse, the link is to my own university :S
I hate how he keeps having to shorten what he's saying, I wish he could just have all the time he wanted to explain this concept as much as the average person could understand.
I love how intense Moriarty gets about things in these videos........it let's you know he really cares about what he is explaining
So entropy is..............
+Matthew Smith The amount of energy in a system unavailable to do work
+Katie Bennie This or just the *amount of possibilities the particles of a system can be arranged*. The best example I heard was with a glass of beer:
When beer is fresh from the tap, it has it's whitecap. Now a whitecap seems more disordered than the beer fluid because the fluid is nice, clear and smooth while the cap is a mess of bubbles. But if entropy always increases, why do I need to put energy into the system of beer (blowing into it for instance) to create new bubbles but when I just leave it alone, the cap vanishes. Because actually in the fluid the entropy is higher than in the cap, because the molecules in the cap are limited to the walls of small bubbles which gives the fluid particles less ways to be arranged than in the open fluid. When the cap vanishes over time, the entropy of the beer increases as the beer molecules sink into the open fluid and are free to float and arrange with the other molecules in the glass.
+bxyify This.
+bxyify
I'm saving this! Perfect example. I know beer.
The number of ways that particles can be positioned
we had a lecture about entropy today, and so many minds were blown.
Explanation isn't very satisfying.
Explanations in quantum mechanics and thermodynamics aren't always satisfying
You two should do a podcast because I could listen to you both all day
I'm not sure that was a better explanation.
That simulation form 6:15 looks a lot similar to the distribution of matter/energy in the universe just at a very increased timescale. First almost uniform distribution, then it clumps into groups connected into threads and lastly an almost empty space.
mr moriarty really got old in the last 6 years. (but he aged well, so no offense)
+karottenkoenig That's Professor Moriarty for you.
+karottenkoenig
Either he was dyeing his hair before and no longer does, or being Sherlock Holmes's main adversary is really tiring. Maybe both.
+Scott Sakurai Or, it could be Heavy Metal poisoning.
I am so glad that this video was made! I have been arguing for not using disorder to describe entropy for a very long time! Thank!
(I might even have made a post in the past one of these videos about it)
I enjoyed the S=k log W where W stands for (number of) ways. In short one could say Entropy is a macrosopic property that quantifies at thermal equilibrium the number of ways energy can be distributed over the entities in a homogeneous system.
I like this bloke - he gets [k]narked quite easily and the more of his videos you watch, the more things you discover upset him.This is thermodynamics for you - even the vaguest understanding of just the tiniest slice of the subject can leave you quick to ire and grossly upset your otherwise gentle condition.
I did wonder why there wasn't much mention of the energy part in the last video. I remember reading an excellent description that made perfect sense to me--you can tidy your house and put everything where it belongs, thus putting the objects in a low-entropy state, but the energy you took to do it, the biological energy and heat energy and mechanical energy and so on of you moving and putting those things in place, that still creates an increase in the overall entropy. You're burning energy in your muscles, exhaling CO2, radiating heat, and so on--that creates more entropy than what you took away by putting everything away.
I think the best way to explain entropy, is by first explaining the concept of the Gibbs Free Energy, and what it means about a system then introduce dG = dH + TdS. Because then dS can be related to its dependence on the temperature. The throw in how with the temperature and the energy flow in the system things either adopt a ordered or disordered state.
I don't know but I will look at those papers for sure.. great topic this one
The equation for Gibbs free energy is actually a simple derivation of the second law.The total entropy change of the universe is given by dG/T. dS in this case merely refers to the internal entropy change of the system, You really need to understand the second law and have a basic understanding of entropy before you can understand the meaning of the Gibbs function.
That's how it's done in chemistry at any rate...
Brady, may i suggest prof. Moriarty make 2 or 3 videos on entropy one for beginners, one for people who took physic after high school and one for experts like his colleges in non physics areas like professional researchers and scientists. i can see that he wants to talk about more advanced topics but doesn't want to confuse everyone. Love the Video!
Would you please POST the TEDx video link.............
Thanks
The crystal example is a bad example for proofing your point because you did not mention the "order" of the water molecules. There are several water mol that solvate the ions. Since that is from view of the water mol much more ordered than being "free",so again the "order" of the system decreases when crystallisation happens through the much higher gain of "disorder" on the "water side".
? So by “making the box smaller” entropy decreases?
And to make the box smaller one needs to decrease the amount of energy needed to do a quantity of work. Is that it?
Ways... that is a great way to visualize it. I think I will keep this in mind next time I get that blank look when I use the word "entropy" in the real world. Seems like a much better way to illustrate it to people who haven't heard of it before. Good vid :)
Why can't more of my university professors be like the guys on Sixty Symbols...
Amazing once more
Well, the problem with order is its subjectivity. What is order? Are the atoms of two different elements ordered when they are in a crystal shape or when they are divided in two seperate volumes?
I don't understand why people find it so hard to understand entropy. The second law of thermodynamics implies that the total entropy of a closed system always increases. It doesn't say anything about the entropy content of individual parts of such a system, who are free to rid themselves of any amount of entropy they wish, provided there is a greater increase of entropy somewhere else in that system. What is so hard to understand about that?
About bloody time Brady! Sixty Symbols all the way. Love hearing Prof. Moriaty rant.
Biology Biology my favorit subject
Naive question: if the entropy term is multiplied with the temperature, does that mean crystallization is "allowed" to produce an ordered structure because it gives of enough heat so the entropy of the system as a whole goes up? i.e. crystallization, e.g. when a slab of steel solidifies in a mill, gives off so much heat because the structure it produces is so ordered as opposed to a merely very very hot liquid cooling down to a much cooler liquid. Or did I misunderstand something?
Soooooo they're effectively replicating high pressures and/ or temperatures?
Thank you for this. I've been stewing on this one for a while. The concepts involved make way more sense to me now. I think the biggest issue with trying to describe entropy is with or need to simplify and boil things down to their most basic components, but for the rules of entropy one has to consider the entire universe and all the time it has experienced.
So is entropy related to the number of different spatial positions a molecule can occupy? In the paper from Lambert it is mentioned only that the energetic micro-states are important, I think (so molecule velocities, vibration frequencies etc.?). So which one is it?
How does entropy always increasing tie in with the Poincare recurrence time discussed in one of the Numberphile videos?
Is entropy directly proportional to the number of ways a system can be arranged. So if entropy increases it doesn't mean that we can't have an ordered system, the chance of this decreases?
I find the videos on entropy to be very interesting but to complex for the format of video that you guys keep releasing. Would it be possible to do a series of videos that explain the base models all the way up to the full complexity of entropy and disorder?
I’m a first year engineering student, and entropy is just one of those things I feel like I totally get one day, and it’s gone the next!
Dr Moriarty is always passionate AND to me makes things a lot clearer >.< Wish I had him as a prof back then!
Stuff moves around and gets scattered in large space and clumped together in small space, is that it?
The cange from amporphed to crystaline in a structure releases heat. Heat has high entropy, so when a system becomes ordered, entropy in universe increases.
does that not mean that as time goes by it will get harder and harder to reduce the localised entropy of a section of a system?
For anyone who didn't take chemistry: the *enthalpy* change, expressed by Hess's law, states that the change in energy (measured as temperature in the classroom in joules and written as ΔH) needed to change one substance to another is constant, regardless of the number of reactions that have happened.
this video gave me a new perspective of what we believe to be order or disorder... perhaps order is merely a matter of perspective, lets say a tesseract in our dimension is perceived as disordered because we lack the understanding to perceive it any other way. so whats to say entropy is to endlessly increase.
- this is a very simple comment about something i dont really understand just trying to gain knowledge.
So would it be accurate to say that entropy is the number of possible states and that the universe prefers more possibilities rather than fewer?
This really bothered me in chemistry class in high school. My teacher adamantly and stubbornly objected when I insisted that her analogy of entropy and disorder was monumentally misleading, and frankly quite outdated. I've recently graduated, but if I ever see her again I will most certainly shove this in her face. Maybe this crudely simplified video will finally make her understand.
I've never had a problem getting my head round entropy and I love some of these explanations. I heard one over on Veritasium where he likened a low entropic system to a single continuous low information and low entropy and then as you add 1s and 0s you add information and increase entropy, until finally the system has to much information to make sense of (white noise) and thus you have the entropic limit.
I personally like the script analogy, but taken a step further, you have a billion page script in order and then you blow it up, but each letter of each page zips of in all different directions, if you slow the explosion down so it takes a few billion years, then the letters will fly apart and form new words, sentences and stories, until finally they all float to the floor and are at rest and at the highest entropic state.
Probably completely misleading analogies, but they work for me :)
Interesting that the data equivalent entropy now seems to be the same as the physics "the number of ways" possible permutations?
Was that always the case?