Entropy Confusion - Sixty Symbols
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- Опубліковано 15 вер 2024
- Professor Phil Moriarty talks about Entropy (again).
Reddit discussion: redd.it/2l6ekd
A little extra bit from this interview: • Entropy (extra intervi...
An article Phil wrote after this video: physicsfocus.or...
LINKS TO MENTIONED VIDEOS & RESEARCH
The first entropy videos --- • Entropy - Sixty Symbols and • Entropy - Professor's ...
Daan Frenkel: www.ch.cam.ac.u...
Sharon Glotzer’s group: sitemaker.umich...
TEDx talk from Glotzer: • Transforming Nanoscien...
Disorder: A Cracked Crutch (not free to read): pubs.acs.org/do...
Visit our website at www.sixtysymbol...
We're on Facebook at / sixtysymbols
And Twitter at #!/...
This project features scientists from The University of Nottingham
bit.ly/NottsPhy...
Sixty Symbols videos by Brady Haran
A run-down of Brady's channels: bit.ly/bradycha... - Наука та технологія
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.
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 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.
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.
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!
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.
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.
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.
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
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
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.
I love how Phil just gets up and struts around in his excitement xD Brady's camera is just all over the room
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 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
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.
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.
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 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.
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.
You're like the first person on the internet to clear up this confusion, thank you.
'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 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.
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.
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?
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.
continue to fight entropy every day gentlemen! i'm 100% behind you!
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!
Yes! Finally a video saying entropy is not disorder
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?
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.
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
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!
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.
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.
I must bookmark this video for the next time I encounter a creationist who cites the second law of thermodynamics as a "refutation" of biological evolution.
i still dont understand what thermodynamics has to do with biology. they assume that earth is a closed system so life cannot exist here without some special intervention, but precisely because its not a closed system i.e. the sun, life could evolve here.
Please do. I love it when creationists think they know science, then you correct them and their smile goes away from there face and they get defensive with all their answers
Or just show them SMBC number 3340
Don't forget to also cite Veritasium's video "What is NOT Random" whenever they bring up "information," too.
Plusy Thermodynamics has everything to do with biology...
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!
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?
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.
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.
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 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!)
I love how intense Moriarty gets about things in these videos........it let's you know he really cares about what he is explaining
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".
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'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 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?
this guy loves what he does. always energetic
It would help if he knew what he is taking about!!!
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....
"AAAAAAAAAAH" - Me after trying to understand this video
I saw him pull out the soccer balls and was like "oh no, they're gonna argue again..."
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
Why can't more of my university professors be like the guys on Sixty Symbols...
Amazing once more
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 have been saying this for years! I need to meet this Lambert, I think I would like him.
I think there's one thing Dr. Moriarty misses here: the main reason that the "disorder" explanation confuses people is that they already have preconceived notions of the idea of disorder. Further, so many people trying to teach the subject neglect to mention that saying that entropy is a measure of disorder _only works as an intuitive explanation for systems of particles_.
It's very simple: entropy is a statistical thing, as described at the end of this video. Teach it like that, and the confusion goes away.
I love this man!
Bana kimyayı bu adam anlatsın yeni element bile bulurum
dont flame please
You love this rude arrogant individual? Really?
In a closed system, his explanation, over time, tends towards disorder... is that it? Not sure it helped me understand any better, but certainly was entertaining to watch
I'm not sure that was a better explanation.
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.
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.
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
People who are confused should read Isaac Asimov's "the last question" and for young people Diane Duane's "Young Wizard" series does a good job of, at the very least spurring interest in scientific ideas and especially entropy. Anyway, as I understand it Entropy is the theory that all closed systems in our universe (and ultimately our universe) trend towards their lowest energy state - aka the heat death of the universe. To me it has nothing to do with order or disorder but simply the amount of potential and kinetic energy locked in a system. The final state of entropy then is ultimately like when you run out of moves in Mahjong or Solitaire - there is no more possible interactions in which energy can be stored or released and in fact. In that way, in my mind, entropy leads to the most stability and so in that way, the most ordered universe possible.
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 think Roger Penrose gives the most clear explanation of entropy in his book "Cycles of Time". As a layman, that's when I really had a "a-ha!' moment, and now this video makes much more sense to me.
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
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 video does not actually explain what entropy is, but it does point out some of the problems with how it is explained. It is causing me to reevaluate how we teach entropy and ask if we are misleading students (even in college) into an oversimplified explanation of what entropy is, how it works and what it means.
I think the simplest statement that we could make about entropy that would actually be true is:
"Overtime, the sum of all processes in a closed system tends towards a Gibbs free energy of zero."
In other words, everything is in dynamic equilibrium and there is no net change in number of things (states occupied).
Mission accomplished - I am now more confused about entropy than ever.
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.
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.
It's actually pretty straight forward if you add the motion into account.
So if you have a crystal forming solution what happens is;
-By random chance 1 atom stick to a surface.
-Now it becomes much more likely that another atom will stick because its just millions and millions of atoms flowing around and they have chemical attraction.
-After another one gets attached now there is more surface for new atoms to latch on so it speeds up exponentially.
-After the crystal grows large enough and solution concentration decreases, the balance of dissolved atoms vs cystallized atoms gets reached.
-This is the point of least entropy since in order to make it into a solution you have to break apart the bonds between the atoms and that requires energy;
Therefore order has nothing to with entrophy, its all about energy and the balance of energy between possible states.
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 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...
I love how Prof. Moriarty has all these props around his office for demonstrations =P
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.
Just thought I would share my understanding of the subject (not that it is the most correct one).
Instead of chaos, entropy is better described using the word freedom. The more freedom a system has - the bigger is its entropy. This nicely describes self organization of hard spheres in a small box - they organize themselves into regular structures because this way they have the most freedom to jiggle around. On the other hand, particles in a larger box would spread out evenly - this way they get even more freedom to move in every direction. This analogy can be applied to messy room as well.
As professor Moriarty noted, whenever there is interaction between particles, things get slightly more complicated. Now particles can either gain or release energy by moving closer or further away from each other. Sometimes it is more favourable for particles to stick onto each other and give more "freedom" to the heat released in the process. This way the total increase of the entropy of the universe (and this is the only thing which matters) will be positive.
The best way I've found to explain entropy is to show people Pascal's triangle, and say that time moves downward. Every new moment of time expands the set of things that exist exponentially, with a pattern of pure mathematical randomness (the bell curve) being produced. This means that as time continues forward, there will always continue to be more and more complex, interesting, and unpredictable things on average, while there are also always still some really boring, simple, predictable things on the extreme edges.
So rather than the confusing terms of order and disorder, I use the terms simple/predictable vs complex/interesting. Flip a coin 2 times and you get a fairly simple set of possible patterns (which I represent with 0 and 1 for heads and tails): 00, 01, 10, 11, or one set/outcome with two heads, one set/outcome with two tails, and one set with two different types of outcomes of a head and a tail (if we care about the order, which we do in real life!). But add just one more bit of time to your coin flipping adventure and you get a bunch of sets and outcomes that are far more complex: 000, 001, 010, 100, 011, 101, 110, 111. This is what we mean when we say that a system has an increase in entropy: more possibilities. Or, as you say more "ways".
Pascal's triangle is also useful for helping people understand the seemingly complex calculation that is the process of entropy in a very simple and physically meaningful way, when we say that those ones and zeros are contraction/matter/particles and expansion/energy/waves instead of heads or tails. Looking at how Pascal's triangle is generated, we can say that entropy is the pattern we get when we divide each of the current categories/sets of things in half, and then recombine those halves with their similar-but-different neighbors (including the "nothingness" on the edges of the triangle) to form entirely new categories of things. It's pretty obvious that no matter or energy is ever lost, since it's all still the same amount of stuff, just all being reorganized into more and more complex patterns.
Also, to connect this to normal day to day life, we can say that each category of things describes all the possible combinations of matter and energy that can be used to make up those types of things (such as things that have two ones and one zero), while each individual thing (such as 110) is it's own unique bit of reality. So, for example, each human has both a shared past and pattern (some particular portion being matter and some particular portion being energy) which makes them similar to all other humans, while also being entirely unique in the grand scheme of space~time. And then we interact with others, genetically and memetically dividing ourselves up and recombining them, to form entirely new kinds of things. So... entropy is also evolution!
I remembered this science daily article on quasi crystals.. Phil Moriarty mentioned it.. would be helpful to cover it more thoroughly. Roger Penrose and others seem to suggest consciousness information (Shannon) entanglement and the arrow of time all gets lumped into the discussion..
"Tetrahedrons are the simplest regular solids, while quasicrystals are among the most complex and beautiful structures in nature. It's astonishing and totally unexpected that entropy alone can produce this level of complexity," said Sharon Glotzer, a professor in the University of Michigan departments of Chemical Engineering and Materials Science and Engineering and principal investigator on the project. "Our results go to the very heart of phase transitions and to the question of how complex order arises in nature and in the materials we make," Glotzer said. "We knew that entropy on its own could produce order, but we didn't expect it to produce such intricate order. What else might be possible just due to entropy?"
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!
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?
You two should do a podcast because I could listen to you both all day
About bloody time Brady! Sixty Symbols all the way. Love hearing Prof. Moriaty rant.
Biology Biology my favorit subject
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.
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 :)
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.
at :27, seeing him age 5 years in 2 sections while talking about entropy. Fairly instructive on its own.
What would really help in all of these discussions is an explanation of the different kinds of energy. Work, heat(Gibbs, Entropy, Enthalpy), potential energy, kinetic energy, electrical energy, etc. Moving socks (varying their kinetic energy) is not the same as putting thermal energy into their molecules and atoms.
I've missed videos with Phil! Like him the most
At one point you should make a video in which Phil really talks about entropy, and with that I mean all the boring, technical details. I understand that this would make the video inaccessible to some of the viewers, but at the same time, for the ones who want to get into details on the topic (e.g. someone who wants to study physics in the future) this would really help.
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?
Another example is structure formation in the universe. This is a spontaneous process, since all particles attract each under due to gravity. In this process, potential energy is converted into kinetic energy, thereby increasing the entropy. All the stars and galaxies (and we) are a (temporary) consequence of the universe evolving from a low-entropy to a high-entropy state.
That was fascinating! Luckily at my university we were never taught entropy as being synonymous with disorder, but instead as a measure of the multiplicity of the system (which could sometimes be seen as disorder). I think we were saved a lot of confusion from that.