I remember watching this as a child when it was first aired and the ideas made a lasting impact. Now I’m about to take on a PhD related to entropy and complex systems. Epic and memorable scene!
Very relatable! It made almost too much sense back then,. of such a fundamental thing as time that, to speak with Neil de Grass Tyson it "made me want to grab people on the street and say: ‘Have you HEARD THIS?
@@Freikinator It came out 10 years ago, so if this person's just starting a PhD, they're probably 22ish, so they could have seen the show when they were 12, which I'd consider a kid.
@@licl4708 As far as our current understanding of things are: entropy can only increase from a lower state to a higher state of entropy, but not vice versa. You live, alive is a state of low entropy, and one day you die, death is a state of high entropy. This suggests that it can't be reversed and therefore you can only move in one direction in time. It's why you experience aging as a linear thing. But that is what we know of it so far, it's what currently seems most likely and what yields the right results in our models. However, we might be completely wrong. Just as our models can be great tools to predict a lot of things, they are not reality. What you try to describe is never exactly the described: e.g. if I pick up the map of England and tell you I have been everywhere in England just by literally standing on the map, you would rightfully call me foolish; the map is only a model. Take Newtonian mechanics, great for most of our current day applications, we even put people on the moon with it, yet it is rubbish once we try to study the quanta (the tiniest particles we know of, such as atoms and their parts). The more we think to know, the less we seem to know. _“We live on an island surrounded by a sea of ignorance. As our island of knowledge grows, so does the shore of our ignorance.”_ - John Archibald Wheeler If you like to think of a new perspective on time, check out dr. Julian Barbour, you can find documentaries where he speaks of time on TH-cam.
This is what you get when you become a true expert in your subject, it's called competence and gives rise to confidence. I wonder how many youngsters have been inspired by Professor Brian Cox to study Science.
I know this is late but this man is absolutely a gem. I've been watching his documentaries all throughout the years and he explains science in such beautiful and poetic ways it just sends a shiver down your spine. People like these are the ones who ignite the spark of curiosity in a child's mind who in turn grows up to do even greater things in life. Hats off to such guys.
Yes time only runs in one direction, from past to future. You cant go into the past unless you have a camera and you can record moments of past and see them in future. That's the closest we have come to time travel. Otherwise tangibly its impossible to go from past to future or future to past because you will disrupt the very laws of universe. Thus time travel is impossible and time runs in only one direction. Time travel is only a myth and fictional.
Legend has it that Brian Cox has never shouted in his entire life......He could be telling me my entire family have been wiped out and that voice would sooth away my grief!
This guy Brian Cox is an absolute legend, everything he's done with his life is amazing, massive respect to him and all the efforts he's put in to being able to do what he loves
@@MrHoldemace 1. He evidently isn't. He literally has credentials that stand up to accreditation and published works to prove so. 2. He's far more accomplished in his life than you'll ever be in yours so why you'd make such an idiotic statement I do not know.
@@jonbateman3245 His band released two albums _"Out of the Dream"_ and _"Blood from Stone"_ - they both flopped. He then went on to join D:Ream _("Things Can Only Get Better")_
I was about 22 when I first saw this on TV when it came out and it stuck with me ever since. Saw Brian Cox live 2 years ago on his tour, he's one of those interesting people you could listen to speak about theories of things for hours, literally. I especially love how he makes it 'accessible' and keeps explanations simple for everyone to keep up.
For anybody confused about the question in the title: Entropy goes from low to high with the passage of time because of the 2nd law of thermodynamics. This works well if time travels in 1 direction. If time traveled in the opposite direction, you should expect the opposite trend which is high to low entropy. This isn't the case (as far we know), therefore time travels in 1 direction.
So it's not really explaining why it travels in one direction, it's proving that it does? But I feel like perception is intertwined with time so maybe we just perceive it in one direction? Still totally confused haha. Thanks anyway.
Yea but how would we know for sure ?😐after all the universe had very low entropy in the first place now it’s having high so when the death of the universe happens from heat death entropy ( could ) decreases 😐and in time you could get a new universe 😐I also think the universe may have some determinism after all how can our lives really be that random ?😐if the universe were to end forever you might as well kick out earth and the universe all to together😑 if our universe is an isolated system witch means nothing goes in and nothing goes out that means out universe is infinite and if it’s finite and it expirences a heat death entropy will decrease 😐leading to a reverse Big Bang or creating another one 😐and if earth formed from evolution why can’t it not form again?😐
@@jettmthebluedragon All process strive for minium free nergy. In the development of thermodynamics, entropy was developed as a parameter needed to increase, when free energy goes down, in any spontaenous process.
@@dropdtune9199 hmm interesting 🤔but why should humans like you and me only formed from the so called Big Bang only 14 billion years ago? When the earth is 4.6 billion years?😐it does not make since 😓the universe could all ready be infinite and we are just living in mot just planet but a patch of it 😐also you say entropy ALWAYS increases so why do scientists say the universe had very low entropy ? 😐you say it always increases so explain why and how entropy was low 😐?
@@davebox588 No, it's upside down. It doesn't matter which way it's being blown by the wind, the top corner on the flag pole should display the thicker white diagonal stripe above the thinner red.
Excuse me sir but Carl Sagan is and will always be the daddy of space and time. If you haven't watched his series 'Cosmos' then do yourself a favour (this was remade by one of his students Neil deGrasse Tyson many decades later)
@@analogpixel We know dude lol. And literally everyone knows about the famed Cosmos series. They were just comparing Brian Cox to another individual. He wasn't designating the GOATs of cosmology or something.
@@Ryan88881 Haha I know, it's just that, nobody who's seen Cosmos would ever utter the phrase "Brian Cox is the David Attenborough of Space and Time".
Imagine you are shown video footage of the wind turning the sand castle into a pile of sand. Now imagine it is played backward. The reverse footage shows a pile of sand spontaneously turning into a castle. You would know immediately that the first video is real and the second one is played backward, not the other way around. It is normal for complex things to disintegrate, but not for complex things to appear out of thin air. That's how you can tell which way time goes. It is also this exact law that contradicts time travel back to the past. (Funnily enough, it is consistent with time travel into the future.)
Which is why the case for the existence of God is very strong. Life, especially as complex as we have it here on earth, is nigh impossible to have come about by random chance, and then be sustained by random chance for so long.
@@loveadeola You can say that it is a strong argument. But not a proof. When I say "it is normal" and the other way around around is not, that doesn't mean that the reverse way is impossible. You know the thought experiment about a monkey with a typewriter: given a lot of time, billions and billions of years, it will create the works of Shakespeare by randomly hitting the keys. It's only a matter of time. As the universe is also billions and billions of years old, sometimes complex, well-structured things do appear out of chaos. It happens extremely rarely, but given an extreme amount of time, it can happen with a reasonably big probability. There's no contradiction: entropy is also a probabilistic thing. A pile of sand can in principle turn into a sand castle by chance, it is just extremely unlikely to happen. So the argument neither proves nor denies the existence of God. Actually, I'm not aware of an argument that does either of the two things, and I think that's just fine. Believing in God is not a scientific matter, but that of faith.
@@loveadeola It is ok for you to believe in any of the thousands of gods humans have conceived. But don't misinform people on science. Evolution is not random chance. Natural selection is not random.
@WordAte the statistical chances that life will spontaneously start on its own based on the initial conditions of the universe without a conscious creator is so astronomically low, that you could as well call it magic.
@@loveadeola Now this is hard to prove. Since we don't fully understand what needs to happen for life to "spontaneously start", it is very hard to estimate its probability. So I'm not gonna call it magic, but you can if you want to.
I started reading a Stephen Hawking book once. A book whers he had, he believed, dumbed down so normal people could understand it. I think i managed about 25 pages. I dont ger this guy either. Surely when he made the sand castle he contradicted himself. Its not extremely unlikely that castles will be made in the sand or they wouldn't sell bucket and spades in the beach shops. The sandcastles get washed away by the sea. Not by wind. Its a good job this guy isnt in Dr. Who or he wouldnt wanna go anywhere "Nah. It'll just be sand by now". I spose at least the daleks would struggle to move about in it.
There isn't really a place for pedants like you; especially in 5 minute video summaring entropy using no maths, aswell as avoiding jargon that would confuse the layman's. He's trying to make physics accessible, and your best rebuttle is to be quibble 😂
@@themanfromvolantis You managed to fundamentally misunderstand absolutely everything Brian said to a point where I don't think there is any explanation of physics possible that you would understand. It's really quite impressive how you utterly missed the point so well it could just as well not have even been said.
The way i understood it is, time moves in one direction to the future because the future will have high entropy because if time would move all over the place or even a circular way, if you could go back in time freely paradoxes would appear such as going back in time and preventing your parents from meeting, etc. That would have low entropy because it would be very complex. Time being Linear would have high entropy, any other way will have low entropy. That's how i got it anyway. Sorry for my broken english.
The past is set so therefore has a low entropy, it is the sand castle. From that castle (time period), forces work against it like the wind in this video and allow for many possible futures, high entropy. The Arrow of Time is entropy. As time passes changes occur and once they occur they can never be undone.
CorsetGrace Agree with all but the last sentence. They can be undone and they do get undone like the sand castle. They get undone in what is essentially the present. However there are many ways that the future can be like, so it's high entropy, so that's why we're moving toward it, as you said. That's what I got out of it but I could be wrong. Just learned about it five minutes ago.
You are not stupid. Instead, the statement that "time moves" is nonsensical. Time is a mental concept. It has no physical reality. It's not even a true dimension: there is no freedom to move on it (in contrast to moving in space). It is always now. Don't take my word for it. Just check your experience.
He is spreading misinformation though, as the statement "time is one directional" is a big dogma in the science world and not really a fact, but just the most mainstream, safe theory out there... But modern evidence and contemporary time models actually point to the fact that time is not one directional, like at all, meaning that in theory it would be possible to travel into the past. Brian Cox is not some big out of the box thinker, but a mainstream science marketer.
@user-ky5dy5hl4dI think the past has a lower entropic state which is why it’s always going forward, although it may have nothing to do with entropy as time is a dimension
@user-ky5dy5hl4dTime is a human concept - at least the way we perceive it. Our brain is hardwired to detect the vector from a lower state of entropy towards a higher state, and represent it in our minds as a "feeling of motion from the past towards the future". Just like we perceive electromagnetic radiation within certain wavelengths as "colors". It is all immensely practical for survival, but not necessarily physically correct.
@@Why_did_TH-cam_add_handles I know nothing about physics but this makes me think of when people refer to the past as “simpler times”. Maybe they’re describing their perception of a lowerentropic state 😄
Yes time only runs in one direction, from past to future. You cant go into the past unless you have a camera and you can record moments of past and see them in future. That's the closest we have come to time travel. Otherwise tangibly its impossible to go from past to future or future to past because you will disrupt the very laws of universe. Thus time travel is impossible and time runs in only one direction. Time travel is only a myth and fictional.
I like how speaks this English man. By the way, that ghost town half buried by sand is called Kolmanskop, it is in the Namibian desert, and it was a diamond mine. By 1954 it was completely abandoned.
I can imagine Christopher Nolan watching it some 10 to 15 years ago, and tell himself that would make a fantastic sci-fi thriller plot. That was both mind blowing and well shot.
since entropy always increases as time passes, time will not run backwards. If it were to run backwards, entropy will have to decrease which then breaks the law of thermodynamics.
+Kai Wen Lum _"since entropy always increases as time passes, time will not run backwards. If it were to run backwards, entropy will have to decrease which then breaks the law of thermodynamics."_ Unfortunately, there is a fatal flaw in this statement. Specifically, the _"as time passes"_ part. Or, to put it in synonymous terms: _"as time moves forward"_. That's the crux: the Second Law of Thermodynamics only tells us something about the case in which time *already* runs forward. Time running forward is the *premise* that is required for the Second Law to hold. Therefore, the Law can, by definition, never be used to explain why said premise *must* always hold. It's like trying to prove the existence of a God _[which I don't believe in, for the record]_ by means of an established truth that starts with _"If (a) God exists, then [...]"_. You can't prove a statement by means of another statement if the second statement relies on the first statement being true.
Yes. This is what they call circular reasoning. I think somewhere in the editing or production process the logical structure of the argument must have been lost. Now we're left with some super flimsy albeit intriguing nonsense.
Ahsim - As in with Maths, there exists Axioms. Without such preconditions, then the whole science cannot hold. Let's take cooking for e.g. baked 220 degrees celcius for 10mins and it's cooked. Granted varying atmospheric pressure it will change but generally speaking it will be cooked as designed. Let's take your presumption, that we cannot assume the thermodynamics to hold. However one would have to ask with all the observation and experiment that we know of to date, is there an existence that this holds, whereby time is not a factor? Hence physics theorem is as far as we acknowledge of the observable paradigm.
I hated physics as a kid in high school. It all seemed so theoretical, so foreign. But now 20 years later watching these documentaries by Cox these concepts seem tangible, even beautiful like a painting. Well done! I wish we had more science teachers like that. People who can communicate these things in a hands-on manner. Music and art classes provide the intuition to understand context and connections as well. So the hard sciences and the arts (and sports) do complement each other.
Interesting. I found that for chemistry (since what was happening at a molecular level was rather abstractly related only to any experiments we could perform), but not for physics. We did little experiments regularly, practically modelling and testing whatever it was we were learning about at the time (well, except for a few things like radiation), and it was the hands-on link between theory and prac that I most enjoyed.
Unfortunately the physics you learn in school isnt all fun and games, rather it helps us solve earthly problems and make money. Thatd be amazing if it had even a little philosophy and pop science though, just to inspire kids even if they have to get down to the nitty gritty stuff first.
Yeah my physics class was trash too actually. Although it is entirely possible you as an adult now are well more rounded say Vs.. your highschool self :p So maybe finding these concepts finally tangible is a result of that.
This is why I always feel like nothing is ever as “perfect” or “designed” as it was first meant to be, once something is put into motion it will continue to degrade/ depreciate as time goes on, until a force is placed upon to change the current path
Someone said to me "if you can't explain something simply, you most probably don't understand the subject enough". That's why Brian Cox and Neil de Grasse are definitely one of the best scientists.
I've long heard the entropy explanation for why time only appears to move in one direction, but I often wonder if we haven't been looking at time altogether incorrectly. We always seem to treat it as some mathematical abstraction, or some linear line of events, tacked on at the last minute to our understanding of the physical universe. But I've pondered the notion that perhaps time is actually _cumulative_ -- that it doesn't move or travel so much as it merely continues to add to itself, like an ever-expanding sphere. I don't have the physics knowledge to be able to actualize this idea, but I know that time is already recognized as integral to the composition of space (space-time). I simply suspect it has more of a 'physical' presence than is currently believed. If so, it _could_ help explain the ever-increasing rate of expansion of the universe, what we now attribute to "dark energy" (which NOBODY understands).
That is why we must fight to protect its artistic integrity from the interference of petty fogging politicians who try and do it down at every turn - it is only one small step to Trumpism and one small stride from North Korean crack downs.
Amazing comparison of sand and wind to ultimately being torn down and reassembled into some other order. Aren’t we all at some evolutionary phase of entropy? Simply a fascinating conversation!
@@cloud42269 if entropy is the involvement of things becoming more chaotic and random over a period of time and evolution is a structured order of all things over a period of time; could we not see this not as one over the other but both, merely separated by phases or portions of time?
No. The castle of sand was assembled by a human being who thought about it using pictures, models of castles, and direct of real castles that were engineered by at least one engineer and/or architect, all of whom had brains with minds that directed their able hands! Those brains and hands were in turn designed by a SUPER ENGINNER, AN ARCHITECT AND the BUILDER of the UNIVERSE! The wind destroys the castle, and the body of sand does NOT "reassemble into some other order! The sand just comes back to the original state of disorder.
Wow. Just wow. The production on this video was so immaculate. From the ‘sands of time’ theme all the way through to the incredible location (I assume it was shot in Kolmanskop, an old abandoned town in Namibia). It took time for YT to recommend this to me but glad it did.
@@skevakler There's an abandoned town in Namibia that looks a lot like this scene- empty houses filled with sand... it was the first thing I thought when I saw it too :)
Brian Cox - you are the most amazing teacher I've ever heard. Thank you for sharing what you know, and explaining it so very well. I've always loved science even though it was not my primary field of study. What lucky students you have!!!
Never saw this before, although I did ALWAYS use another video of his in my classes covering acceleration, atmospheric resistance and terminal velocity. In it, he drops a bunch of feathers and a bowling ball simultaneously, from being suspended perhaps 20 or so meters in the air inside the world's largest vacuum chamber. They, of course, hit the ground at the exact same time. Great to watch!! This is a novel and utterly (IMHO) perfect way to explain time's flow. Never have I seen anyone better define such an abstract as 'time' by explaining its simple adherance to the laws of Physics, and specifically Thermodynamics. It also proves the only other decent explanation for time I'd ever seen....that " Time is a measurement of change." VERY well done, and Thank you, Professor Cox.
There is a problem with Brian's claim. If increasing disorder creates the arrow of time then that means that time must reverse, every time entropy decreases and things get more complex. That include biological systems, evolution, human development and technology and that is clearly not true. Another issue about entropy is that it was formulated by studying gases which are fairly unstable. Not by studying solids like diamonds that can maintain structure for huge periods of time.
@@Andrew4Handel Yes, if it is 'highly unlikely' that entropy will decrease, that means that it CAN decrease, and therefore that would mean that (very rarely) time would run backwards. Entropy is a measure (perhaps a symptom) of the arrow time, not its cause.
Wow, I truly like this guy. My dad says that when a person knows something they are able to explain it so that anyone could understand. They don't need fancy words to make others puzzled, but they can make things simple. And this guy here knows how to do that. It means he actually knows what he is talking about.
Time can be expressed by measuring a difference in entropy. The big bang had low entropy, yet now we have much higher entropy and it will continue to increase... Or something like that
Best and clearest explanation of the 2nd Law of Thermodynamics I've come across! Well, done! Brian Cox and thanks for being such a great science teacher!
I think we are missing the second and most crucial part where Brian explains exactly why the 2nd law of thermodynamics demonstrates why time travels in one direction !
I agree 100%. A great explanation THAT time travels in one direction but no how and why to go with it. If this is related to the expansion on the universe then he needed to mention it.
what a beautifully shot and explained film. I remember watching this with my father when I was little and remembering the profound impact it had on me, Im glad I've come across this video to remember me of those times.
Wow I got recommend this 10 years later, but I am not mad. I revel in knowledge and love to learn. Not to mention Brian Cox voice is so soothing and just facilitates my ability to learn by demanding all my attention without suggesting it as in yelling at me to listen.
Time and space are intimately linked and the progression of time is relative, not absolute. There is nothing in physics that says time must flow in a certain direction. Space can also be folded by gravity; therefore traveling back in time is possible if you can fold two ends of space together, ie., the beginning and end of any distance traveled.
It could also be be with the death of the universe entropy falls back in time 😐or if it does not 😐time always goes forward then eventually leading to a new universe if you think about it the universe had very low entropy😐after all I have realized the universe could have some determinism to it as well after all we could have Ben anything or anyone so why are we human 🤔in specific points if this planets history 🤔it seems off 🤔
I always feel more at ease with death itself when I listen to Brian Cox. I guess it's just the way he calmly explains how this all fits, and how it's all good, even if our brains struggle with the unknown...especially death.
By far WoTU was my favorite of the Wonders series and my favorite "science/physics/space" documentary ever. I really would love if they revisited the WoTU episodes and did new ones with updated information.
Fantastic lesson as usual. I don't know if Brian still works as a lecturer for a University at all but if he did, I'm sure he would dramatically raise the uptake, retention and pass rates, easily! It would be brilliant to be part of a "live" lecture with him guiding the ship.
Yes, everything is moving towards entropy. Moving towards change. Everything changes along the way. Everything... Nothing escapes it. It doesn't matter to what it changes to, it just does it. Our lives are nothing but matter changing within the movement of the universe. We assign a numerical measurement "time" so we can understand the movement of entropy. Brian explains it very well. The order and speed of matter's movement at the universe level is in one direction and that direction is to total decay of matter down to the smallest parts of matter. At this time of our knowledge, down to the quatum level. Then the question is, "where does it begin to reassemble?"
If you go to 0:30 and take Brian Cox out of the image, you’re left with something incredibly similar to the artwork for Tame Impala’s album ‘The Slow Rush’...which is all about time 🤔
Yes time only runs in one direction, from past to future. You cant go into the past unless you have a camera and you can record moments of past and see them in future. That's the closest we have come to time travel. Otherwise tangibly its impossible to go from past to future or future to past because you will disrupt the very laws of universe. Thus time travel is impossible and time runs in only one direction. Time travel is only a myth and fictional.
@@GeekRaj time travel to the future is possible... To the past is still a bit debatable.. There are ways which we can use to achieve this... We might need tonnes of negative energy, or stuff like that which might be very hard to gather, but it's definitely plausible
I dont get why you don’t get it. The total ammount of disorder in the universe which is measured by entropy always increases with time. So time moves only in one direction! Into a high entropy state of the universe.
@@majdsafa4009 Because he has reached the limit of his understanding. Some people simply can't wrap these advanced ideas or concepts arround their heads. I'm not criticizing him or insulting him in any way, shape or form. I'm just making an educated guess, because he is stuck at the analogy with the sand castle, and can not see beyound that.
I totally agree . Beause according to thermodynamics,time only flows in one direction . For example , a glass falling from the table and breaking into pieces represents increased chaos in the system.
I wish that everyone spent a bit more time watching and learning about these things, instead of dedicating so much precious time to mind numbing social media. Motivation, education and dedication can change the world. Thank you Mr. Cox.
To be fair, for some reason, at twenty to 6 in the morning, this came into my mind so I'm here. The professor has entered my dreams via the flow of time to get me here, odds on
This is the man that got me interested in science and physics. Just watching his shows has pretty much defined how my aspirations have turned out. And now I plan to study Physics in higher education. Prof Brain Cox, legit cool dude.
'Apologies in advance for pedantry but words do matter, particularly when it comes to the understanding of scientific ideas. Brian Cox describes entropy in terms of being able to re-arrange the grains of sand and still keep the sand pile the same [shape]. As a non-scientist, isn't this contradictory? If something has been rearranged then it is, by definition, different. Also, around the [4:52] mark Brian states entropy always increases because it is overwhelmingly more likely that it will. That is fine as an observation but as an explanation it doesn't tell us anything as it sounds circular, as in "Entropy increases because it does."
What Cox is saying is that of all the trillions of ways that sand grains could be arranged, there are far (far) more arrangements that form a bell-shaped pile than that form a castle-shaped pile. So every time the grains are randomly changed you are most likely going to see the the sand grains arranged to become more and more bell shaped. In other words, entropy increases because there are more high-entropy states than low entropy states. So, every time a system is randomly changed from one state to another available state, the new state is probably higher entropy (i.e., entropy is likely to increase) Also, there is a maximum entropy and as you get closer to that maximum there will be little meaningful change to the shape the sand creates from one state to the next. Once bell shaped, rearranging the individual grains of sand is unlikely to change the bell-shaped. The locations of individual grains of sand can change a lot without changing the bell-shape( i.e., there are trillions of arrangements of sand that produce the same bell shaped pile).
Yeah some more time on that would have been good. Presumably it's along the lines of, when you age & die your body might decay & be dispersed in many ways but the probability that it will reform as you with the spark of life is not equal to all other options, therefore it goes forward but not backwards? I'm guessing that's the inference, but it seems separate to why we wouldn't walk backwards & talk & think backwards - if we did we'd be unremembering so we wouldn't know we were - but we use gravity to walk (fall forward) so there's that, but it still feels only half answered.
I'd really like to think that Professor Cox is having the same effect on this generation as Carl Sagan had on mine. His enthusiasm is contagious, and I could listen to him all day.
+Neil Thompson now "knows" that wind can randomly make sandcastles by blowing sand about 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001% of the time ;)
I may not remember this correctly, but the wind has difficulty creating a sandcastle because the energy of the wind is incoherent, in the same way ambient light, also incoherent, doesn't cut us up like a light saber. Coherent wind, in the form of a air gun maybe, could blow the sand into a smooth wall on the north side, then move to the south side etc. etc. until the shape of a sand castle is achieved. This however requires an expenditure of energy beyond the energy of the wind to focus it's power. Coherent effort, in the form of the mold and the worker, creates a sandcastle faster than random wind.
Gordo Hogo, it's more or less that. It's related to the concentration of energy of the wind: the energy per unit area. Building a castle would require just the right distribution of energy concentration in the wind, which is why it is highly unlikely. Coherent wind, such as an airgun has high concentration and thus can be directed in order to distribute its energy to the sand in the right way. Incoherent wind has a more even distribution of concentration, and for a given amount of energy, the concentration of an incoherent wind is much less than that of a coherent wind, so it cannot easily be directed to form a specific shape. Statistically speaking, an even concentration distribution is more likely than an uneven one, because if the distribution is uneven, the energy will flow until the distribution is even (like heat). Things with high entropy like the sand pile or incoherent wind have even but low energy concentrations, which is why there are so many ways of making these things and why they are much likelier than their ordered, super concentrated, alternatives.
I think it's also important to point out that our observational understanding of time is borne from us operating as biological structures that survive in a world we're time appears to flow forward and every significant thing we interact with seems to be doing the same. . "The Order of Time" by Carlo Rovelli is a great book 😊
Yea but it could be that time is just an illusion 😑after all what do you remember before you were born ? That’s right nothing 😑nothing but darkness if you can’t even remember events before the day you were born what makes you think time had a beginning? 😐you were all ready dead for who knows how dam long 😑your mind can’t accept it beacuse your alive 😐the truth is the universe could be indefinitely old it’s just or brains can’t handle it 😑you have to think before you were born before earth before the soylar system before the milkeyway before if our milkey way is part of a merger or not and you have to think about the previous galaxies and galaxies That came before those all Those planets stars etc you would have no idea and before those galaxies ever came to be before who knows what else and even if the universe is finite you would have idea what caused everything to begin with and what happens before the moment of creation 😑this may be to much to your brain to handle 😐it’s just that you don’t realize it
A compelling way to ultimately explain death and the universe. Before we are born we are nothing but atoms, we then exist as a being with low entropy form until one day we will have the same high entropy form as ash before returning to nothing but atoms. Its simultaneously beautiful and terrifying to think about.
If Brian Cox can be a professor waffling on about his unproven theories( won't even go into global warming) what degree should Jimi Hendrix have received playing and singing the most amazing music ever in the Universe!?! Ok , in our galaxy.
I love using the 2nd law of thermodynamics and entropy to explain some moral issues and enforcing values to my students. For example, it is easier to do bad things; it is hard work to stay good. That is because to decrease entropy of a system (towards order due to doing good things), the surrounding (including my students) must exert work towards the system. This will increase the entropy of the surrounding (muscle breakdown, consumption of food molecules, etc. due to excertion of effort, use of resources and energy). Another way of stating this is, it is easier to make a mess of my room than to keep it clean and organized.
From what I think I've gathered from this video is that the amount of Entropy an object has corresponds to the likelihood of it's particles forming the same structure when rearranged. I'm sure it's much more complicated than that though.
Cox and Greene often make elaborate analogies to describe their theories, making their books (and videos?) annoying to read. I don't know if I can do much better but Entropy is the 'degrees of disorder' in an isolated system (eg. Universe) and is goverened by the 2nd law of thermodynamics which says generally* that chemical/physical processes always occur (spontaneously) from a state of order to disorder over time always *increasing* Entropy towards thermodynamic equilibrium. Understanding what Entropy is (as you hope might kill you?) is fairly straight forward. As I said above it's just the state of disorder in a system. The example of an egg (high order, low entropy) is often used. If you break that egg (low order, high entropy) it's impossible to restore it to it's previous order. Pouring cream into your coffee will spread through the cup (higher disorder [Entropy]), you'll never see it clump up in one highly ordered region of the cup ... and other innumerable irreversible natural processes (which the second law can now explain the nature of this asymmetry). As a consequence of the second law of thermodynamics definition that the total entropy (of an isolated system) is *always* increasing (including the Universe itself, it's far more disordered now then when it began) an asymmetry between future and past must exist because ... it *only* increases over time, it can never decrease so we know time has an arrow (only moves in one direction) and can actually use Entropy as a *very rough* way of distinguishing something from the past from the future. He basically just took 5:30 to explain what the second law of thermodynamics states instead of just using the stupid egg example I gave you (and that all teachers have used for decades) or any simple irreversible natural process and there's really nothing to explain short of 'things happen asymmetrically (towards higher Entropy) over time (cause and effect) so time itself is asymmetric (has an arrow or 'direction'). *There's a ton of math shit, I'm just giving you a quick answer, Entropys' quantity (S) is formally defined as S = kBlnΩ and ΔS = δqrev/T
@@MaskOfAgamemnon You're asking the difference between positivity and negativity; there is none, because it's a matter of perspective. An example: An electron is negatively charged, and a positron is positively charged. If time ran backwards it would NOT be the opposite... It would be the exact same as time moving forward if we replaced all electrons with all positrons, and all positrons with all electrons, or didn't change their charge at all. Charge does NOT determine the arrow of time. Look into Charge Parity Symmetry if you want to know more. Basically, physics must work the same whether time is going forward or backwards. Entropy, on the other hand, DOES determine the arrow of time. Entropy is a phenomenon that is less binary than +/-, because it has nearly infinite values in between order and disorder. It just so happens that what we observe is that disorder is the probabilistic state of the universe. Look into bifurcation theory if you want to know more. Cox even explains, "the sand in this pile is equal to the sand in that pile." So, you're fundamentally looking at the explanation wrong, it's not that the explanation is wrong. Imagine a box, with 50 particles and 50 anti particles. If two collide, they annihilate. Entropy states that, over TIME, the box will be EMPTY. That's it. So, it doesn't matter if we start with 50/50 particles, or if we do the opposite and reverse time so we start with 0/0; you'll always end up with 0/0, an empty box. Entropy prefers disorder, regardless of if the system was in order or disorder to begin with (the only thing that would change if you reversed time)
@@MaskOfAgamemnon Think of it like this. You have an x and y, x is time and y is what is happening at that time. For example, like a birthday, there is a specific time and date(x) for a specific event(y). So you have a linear timeline of events, whether you move forwards or backwards( no paradoxes involved). Think back to the sand castle imagine yourself watching the wind scatter the castle back into the desert, like expected. Ok, now take the same experience, and make time go backwards. What you see this time, is that the scattered sand will gather to make the sand castle, something highly unexpected. So what can you conclude from this? That time has to obey the laws of entropy because overall, entropy is always increasing as time moves forward and by going backwards in time you are breaking the laws of entropy.
@@MaskOfAgamemnon yes, quite silly explanation. It’s more like entropy has to obey the linearity of time than the opposite (if we need to make that meaningless relationship)
I gotta stop watchin this mf while I’m high I be wantin to quit my job and study stars and shit and also Brian wth you in the damn desert for anyway you know they got sand at the beach?
Yeah, I’ve wondered why he had to go all the way from Manchester to Namibia to explain that when he could have just gone to the beach at Blackpool. Come to think of it, if you want to see entropy on a human level, Blackpool’s bloody perfect.
As an engineer and having taking a lot of classes, I dealt with entropy in Thermodynamic and Heat Transfer classes the most. I always used this simple example to describe entropy: You can never unscramble an egg
My high school best buddy --and later in college too--used to have talks with me like this. He knew I didn't understand the math or the physics, and if I added anything to the conversation he'd go along with my childish thoughts and compliment me. Unfortunately, he's become a radicalized political ideolog and I can no longer have even casual conversations with him. Extremely intelligent people seem to go this way often, and it is such a gift to have a genius like Cox stay so plainfully down to earth. Thanks for posting!
Brian Cox is the Carl Sagan of our time, and I am privileged to be able to listen to and watch him explain science. He is a breath of calm in a world of chaos(entropy).
So - why does time goes only in one direction? Because entropy tends to rise. Why? Because it it overwhelmingly more likely to do so. Thanks Brian, now it is absolutely clear!
Excellent simple video explaining entropy, Brian has an amazing skill. So after watching this video (3 times!) I'm assuming that the transition of low to high entropy is the natural process of most interactions? If this is the case then how are low entropy states formed, are they the result of high energy? In regards to time reversal, I'm going to assume that every entropy transition process is impossible to replicate because of the complexity involved. Put simply it can happen but it won't.
I'm not an expert by any stretch but I believe that low entropy states are the occurrences of the extremely low probabilities which Brian is talking about here. If you consider the entire universe to be the sand castle it can be imagined as one entire system moving from low entropy (high order) to high entropy (low order). As for why the universe began with such low entropy, we don't really know.
Very nicely, very impressive. Entropy was my most favorite topic in physics way back during my 12 grade time/ around 40 years back, and still I am fascinated by the simplest idea leading to such a huge understanding ....
Sandcastles are overwhelmingly unlikely to form in the wind - this makes me really appreciate how overwhelmingly unlikely and precious structured creations like humans are
mmmm.... so just realize there is a major difference in those two processes. The sandcastle is just a placement process where relationship between the component parts is effectively independent of the other parts save the results of collisions due to shape and what not... whereas, the organic chemistry of life and the biological components that support it are very exclusive, very precise, and depend on finding the lowest energy state possible in terms of conformation of the molecules and the atoms/molecules involved. In other words, there are nearly uncountable ways to organize sand with sand, but in the case of chemistry, there are far less ways, and the system will find it's lowest energy state by itself, which is why chemistry is a predictable and understandable science. From a distance the complexity of a human seems unfathomable, but when you zoom in and look at a specific subsystem and how it works and it's small chemical structure and function, you see a repeating pattern of being in the lowest energy state, departing from it due to a specific interaction/stimulus, and then returning to that same lowest energy state. All these simple operations summate to a complex system, but the parts are simple... in the same way an economic transaction is simple, but when aggregated into an economy, they are not, and yet the whole complex economy is still reducible those same simple transactions.
I remember watching this as a child when it was first aired and the ideas made a lasting impact. Now I’m about to take on a PhD related to entropy and complex systems. Epic and memorable scene!
Very relatable! It made almost too much sense back then,. of such a fundamental thing as time that, to speak with Neil de Grass Tyson it "made me want to grab people on the street and say: ‘Have you HEARD THIS?
How old is this show? It looked pretty new to me... I must be stuck in a time warp...
@@Freikinator It came out 10 years ago, so if this person's just starting a PhD, they're probably 22ish, so they could have seen the show when they were 12, which I'd consider a kid.
Congrats!
@@licl4708
As far as our current understanding of things are: entropy can only increase from a lower state to a higher state of entropy, but not vice versa. You live, alive is a state of low entropy, and one day you die, death is a state of high entropy. This suggests that it can't be reversed and therefore you can only move in one direction in time. It's why you experience aging as a linear thing. But that is what we know of it so far, it's what currently seems most likely and what yields the right results in our models. However, we might be completely wrong. Just as our models can be great tools to predict a lot of things, they are not reality. What you try to describe is never exactly the described: e.g. if I pick up the map of England and tell you I have been everywhere in England just by literally standing on the map, you would rightfully call me foolish; the map is only a model. Take Newtonian mechanics, great for most of our current day applications, we even put people on the moon with it, yet it is rubbish once we try to study the quanta (the tiniest particles we know of, such as atoms and their parts). The more we think to know, the less we seem to know.
_“We live on an island surrounded by a sea of ignorance. As our island of knowledge grows, so does the shore of our ignorance.”_ - John Archibald Wheeler
If you like to think of a new perspective on time, check out dr. Julian Barbour, you can find documentaries where he speaks of time on TH-cam.
I love the way he talks, so gentle and happy
So nice to see a gamer who also loves physics! Keep making excellent gta vids
@@ctboy1989 those two interests are way more common than you think man
Talks like Roger Waters.
This is what you get when you become a true expert in your subject, it's called competence and gives rise to confidence. I wonder how many youngsters have been inspired by Professor Brian Cox to study Science.
@Yao Jie Wong 0
I know this is late but this man is absolutely a gem. I've been watching his documentaries all throughout the years and he explains science in such beautiful and poetic ways it just sends a shiver down your spine. People like these are the ones who ignite the spark of curiosity in a child's mind who in turn grows up to do even greater things in life.
Hats off to such guys.
You heard the infinite monkey cage?
@@n0body550 it's great.
totally agree with you
Yes time only runs in one direction, from past to future. You cant go into the past unless you have a camera and you can record moments of past and see them in future. That's the closest we have come to time travel. Otherwise tangibly its impossible to go from past to future or future to past because you will disrupt the very laws of universe. Thus time travel is impossible and time runs in only one direction. Time travel is only a myth and fictional.
@@GeekRaj You bursted my bubble, but i like to think there is a way in which we can time travel to the past and future regardless of percentage
I can listen to Dr Cox all day with the enthusiasm of a child in his voice. He makes it easier to understand imo. Thank you
Legend has it that Brian Cox has never shouted in his entire life......He could be telling me my entire family have been wiped out and that voice would sooth away my grief!
Pretty sure he was in a rock band in his youth!
@@avocajoe1916 D-Ream were not a rock band, pop...and he played keyboard!
@@Gavinlovesfishing haha thats even better tbh!
Truth is his students think he's a shit lecturer at uni
Try telling him aliens don't exist
This guy Brian Cox is an absolute legend, everything he's done with his life is amazing, massive respect to him and all the efforts he's put in to being able to do what he loves
He also has a painting in his attic that ages so he doesn't have to. True story.
He's grade A , moron !
@@MrHoldemace
1. He evidently isn't. He literally has credentials that stand up to accreditation and published works to prove so.
2. He's far more accomplished in his life than you'll ever be in yours so why you'd make such an idiotic statement I do not know.
@@Nine-Signs Accomplished because he was a singer firstly . Memories of education means jack , real physics disagrees with dogma .
@@MrHoldemace 2:05 I'm surprised he didn't build a pyramid 😉
You can tell Brian Cox is very passionate about what he says and tries to explain it as easy as possible for the audience. much respect for this guy
I want to see him playing keyboard in his failed band "Dare"
@@TonyEnglandUKhow did they fail?>
@@jonbateman3245 His band released two albums _"Out of the Dream"_ and _"Blood from Stone"_ - they both flopped. He then went on to join D:Ream _("Things Can Only Get Better")_
@@jonbateman3245 Apparently, Brian is a good keyboard player, though.
@@TonyEnglandUK he’s not done too bad then, I wouldn’t call him a failure, but we all have different views which is cool.
I was about 22 when I first saw this on TV when it came out and it stuck with me ever since. Saw Brian Cox live 2 years ago on his tour, he's one of those interesting people you could listen to speak about theories of things for hours, literally. I especially love how he makes it 'accessible' and keeps explanations simple for everyone to keep up.
For anybody confused about the question in the title: Entropy goes from low to high with the passage of time because of the 2nd law of thermodynamics. This works well if time travels in 1 direction. If time traveled in the opposite direction, you should expect the opposite trend which is high to low entropy. This isn't the case (as far we know), therefore time travels in 1 direction.
Thank you👍🏻
So it's not really explaining why it travels in one direction, it's proving that it does? But I feel like perception is intertwined with time so maybe we just perceive it in one direction? Still totally confused haha. Thanks anyway.
Yea but how would we know for sure ?😐after all the universe had very low entropy in the first place now it’s having high so when the death of the universe happens from heat death entropy ( could ) decreases 😐and in time you could get a new universe 😐I also think the universe may have some determinism after all how can our lives really be that random ?😐if the universe were to end forever you might as well kick out earth and the universe all to together😑 if our universe is an isolated system witch means nothing goes in and nothing goes out that means out universe is infinite and if it’s finite and it expirences a heat death entropy will decrease 😐leading to a reverse Big Bang or creating another one 😐and if earth formed from evolution why can’t it not form again?😐
@@jettmthebluedragon All process strive for minium free nergy. In the development of thermodynamics, entropy was developed as a parameter needed to increase, when free energy goes down, in any spontaenous process.
@@dropdtune9199 hmm interesting 🤔but why should humans like you and me only formed from the so called Big Bang only 14 billion years ago? When the earth is 4.6 billion years?😐it does not make since 😓the universe could all ready be infinite and we are just living in mot just planet but a patch of it 😐also you say entropy ALWAYS increases so why do scientists say the universe had very low entropy ? 😐you say it always increases so explain why and how entropy was low 😐?
"I'm going to create some order in the universe" *colonises the desert*
He already brought a flag. Doing a proper job.
@@janpeternelj2309 Which is upside down...
@@Climpus no, it's showing the reverse side.
@@davebox588 No, it's upside down. It doesn't matter which way it's being blown by the wind, the top corner on the flag pole should display the thicker white diagonal stripe above the thinner red.
O
Prof Brian Cox is the David Attenborough of Space and Time. Both national treasures
Excuse me sir but Carl Sagan is and will always be the daddy of space and time. If you haven't watched his series 'Cosmos' then do yourself a favour (this was remade by one of his students Neil deGrasse Tyson many decades later)
Can't stand him. I heard he added "Ucker" to his surname.
@@analogpixel We know dude lol. And literally everyone knows about the famed Cosmos series. They were just comparing Brian Cox to another individual. He wasn't designating the GOATs of cosmology or something.
@@Ryan88881 Haha I know, it's just that, nobody who's seen Cosmos would ever utter the phrase "Brian Cox is the David Attenborough of Space and Time".
@@analogpixelCarl Sagan is a yank. David and Brian are fine english gentlemen, don’t compare them to a yank please.
Imagine you are shown video footage of the wind turning the sand castle into a pile of sand. Now imagine it is played backward. The reverse footage shows a pile of sand spontaneously turning into a castle. You would know immediately that the first video is real and the second one is played backward, not the other way around. It is normal for complex things to disintegrate, but not for complex things to appear out of thin air. That's how you can tell which way time goes. It is also this exact law that contradicts time travel back to the past. (Funnily enough, it is consistent with time travel into the future.)
Which is why the case for the existence of God is very strong. Life, especially as complex as we have it here on earth, is nigh impossible to have come about by random chance, and then be sustained by random chance for so long.
@@loveadeola You can say that it is a strong argument. But not a proof. When I say "it is normal" and the other way around around is not, that doesn't mean that the reverse way is impossible. You know the thought experiment about a monkey with a typewriter: given a lot of time, billions and billions of years, it will create the works of Shakespeare by randomly hitting the keys. It's only a matter of time. As the universe is also billions and billions of years old, sometimes complex, well-structured things do appear out of chaos. It happens extremely rarely, but given an extreme amount of time, it can happen with a reasonably big probability. There's no contradiction: entropy is also a probabilistic thing. A pile of sand can in principle turn into a sand castle by chance, it is just extremely unlikely to happen.
So the argument neither proves nor denies the existence of God. Actually, I'm not aware of an argument that does either of the two things, and I think that's just fine. Believing in God is not a scientific matter, but that of faith.
@@loveadeola It is ok for you to believe in any of the thousands of gods humans have conceived. But don't misinform people on science. Evolution is not random chance. Natural selection is not random.
@WordAte the statistical chances that life will spontaneously start on its own based on the initial conditions of the universe without a conscious creator is so astronomically low, that you could as well call it magic.
@@loveadeola Now this is hard to prove. Since we don't fully understand what needs to happen for life to "spontaneously start", it is very hard to estimate its probability. So I'm not gonna call it magic, but you can if you want to.
This is by far the best explanation for entropy I've ever heard
I started reading a Stephen Hawking book once. A book whers he had, he believed, dumbed down so normal people could understand it. I think i managed about 25 pages.
I dont ger this guy either. Surely when he made the sand castle he contradicted himself. Its not extremely unlikely that castles will be made in the sand or they wouldn't sell bucket and spades in the beach shops.
The sandcastles get washed away by the sea. Not by wind.
Its a good job this guy isnt in Dr. Who or he wouldnt wanna go anywhere "Nah. It'll just be sand by now".
I spose at least the daleks would struggle to move about in it.
@@themanfromvolantis Yeah, you really don't get it 🙂
There isn't really a place for pedants like you; especially in 5 minute video summaring entropy using no maths, aswell as avoiding jargon that would confuse the layman's.
He's trying to make physics accessible, and your best rebuttle is to be quibble 😂
@@themanfromvolantis You managed to fundamentally misunderstand absolutely everything Brian said to a point where I don't think there is any explanation of physics possible that you would understand. It's really quite impressive how you utterly missed the point so well it could just as well not have even been said.
I might just be stupid, but I don't understand how that explained the whole 'time moves in one direction' thing at all
The way i understood it is, time moves in one direction to the future because the future will have high entropy because if time would move all over the place or even a circular way, if you could go back in time freely paradoxes would appear such as going back in time and preventing your parents from meeting, etc. That would have low entropy because it would be very complex. Time being Linear would have high entropy, any other way will have low entropy. That's how i got it anyway. Sorry for my broken english.
The past is set so therefore has a low entropy, it is the sand castle. From that castle (time period), forces work against it like the wind in this video and allow for many possible futures, high entropy.
The Arrow of Time is entropy. As time passes changes occur and once they occur they can never be undone.
CorsetGrace Agree with all but the last sentence. They can be undone and they do get undone like the sand castle. They get undone in what is essentially the present. However there are many ways that the future can be like, so it's high entropy, so that's why we're moving toward it, as you said.
That's what I got out of it but I could be wrong. Just learned about it five minutes ago.
You are not stupid. Instead, the statement that "time moves" is nonsensical. Time is a mental concept. It has no physical reality. It's not even a true dimension: there is no freedom to move on it (in contrast to moving in space). It is always now. Don't take my word for it. Just check your experience.
CorsetGrace thanks for that... after reading it out loud a few times its kinda clicked
"You cant reverse time, trust me" - The man who gets younger with age
@Repent to Jesus Christ Repent to Jesus Christ IDIOT.
Yeah actually he does
the only way to reverse time is to conviince other people that it can't be reversed.. you get 1 minute back per brainwash
He is spreading misinformation though, as the statement "time is one directional" is a big dogma in the science world and not really a fact, but just the most mainstream, safe theory out there... But modern evidence and contemporary time models actually point to the fact that time is not one directional, like at all, meaning that in theory it would be possible to travel into the past. Brian Cox is not some big out of the box thinker, but a mainstream science marketer.
Entropy has always been my favorite concept of physics. Such a fascinating phenomenon.
@user-ky5dy5hl4dI think the past has a lower entropic state which is why it’s always going forward, although it may have nothing to do with entropy as time is a dimension
@user-ky5dy5hl4dTime is a human concept - at least the way we perceive it. Our brain is hardwired to detect the vector from a lower state of entropy towards a higher state, and represent it in our minds as a "feeling of motion from the past towards the future". Just like we perceive electromagnetic radiation within certain wavelengths as "colors". It is all immensely practical for survival, but not necessarily physically correct.
@user-ky5dy5hl4d Yes, I know, it was just a stupid copy and paste error - corrected, thanks!
@@Why_did_TH-cam_add_handles I know nothing about physics but this makes me think of when people refer to the past as “simpler times”. Maybe they’re describing their perception of a lowerentropic state 😄
therefore, it is unlikely that some machine can reverse entropy and makes us go back in time, am I right?
More fascinating than entropy and time travel is how he managed to not get any sand in his eye
He got plenty of sand in his knickers.
Hairstyle is for a reason
Well, he didn't take a p*ss.
Who says he didn’t? ;)
First law of TH-cam dynamics: every video will be in your recommended list after ten years.
hahahhahahah
Yes time only runs in one direction, from past to future. You cant go into the past unless you have a camera and you can record moments of past and see them in future. That's the closest we have come to time travel. Otherwise tangibly its impossible to go from past to future or future to past because you will disrupt the very laws of universe. Thus time travel is impossible and time runs in only one direction. Time travel is only a myth and fictional.
I like he said " in the 19th century ".
Like, i know i was born when the first ever nintendo came out, but its not that long ago lol.
@@asahmosskmf4639 but you were not born in the 19th century ;)
I like how speaks this English man. By the way, that ghost town half buried by sand is called Kolmanskop, it is in the Namibian desert, and it was a diamond mine. By 1954 it was completely abandoned.
Thank you! I was wondering.
@@tastyanagram there's always someone who knows the obscure.
@@timeconstrained2400 that makes two of us😉
I can imagine Christopher Nolan watching it some 10 to 15 years ago, and tell himself that would make a fantastic sci-fi thriller plot. That was both mind blowing and well shot.
GREAT explanation of entropy!!
AWFUL explanation as to why time travels in one direction...
Title your videos better BBC
since entropy always increases as time passes, time will not run backwards. If it were to run backwards, entropy will have to decrease which then breaks the law of thermodynamics.
+Kai Wen Lum
_"since entropy always increases as time passes, time will not run backwards. If it were to run backwards, entropy will have to decrease which then breaks the law of thermodynamics."_
Unfortunately, there is a fatal flaw in this statement. Specifically, the _"as time passes"_ part. Or, to put it in synonymous terms: _"as time moves forward"_. That's the crux: the Second Law of Thermodynamics only tells us something about the case in which time *already* runs forward. Time running forward is the *premise* that is required for the Second Law to hold. Therefore, the Law can, by definition, never be used to explain why said premise *must* always hold.
It's like trying to prove the existence of a God _[which I don't believe in, for the record]_ by means of an established truth that starts with _"If (a) God exists, then [...]"_. You can't prove a statement by means of another statement if the second statement relies on the first statement being true.
Yes. This is what they call circular reasoning. I think somewhere in the editing or production process the logical structure of the argument must have been lost. Now we're left with some super flimsy albeit intriguing nonsense.
Ahsim - As in with Maths, there exists Axioms. Without such preconditions, then the whole science cannot hold. Let's take cooking for e.g. baked 220 degrees celcius for 10mins and it's cooked. Granted varying atmospheric pressure it will change but generally speaking it will be cooked as designed.
Let's take your presumption, that we cannot assume the thermodynamics to hold. However one would have to ask with all the observation and experiment that we know of to date, is there an existence that this holds, whereby time is not a factor?
Hence physics theorem is as far as we acknowledge of the observable paradigm.
That's not what Ahsim is saying, dude.
I hated physics as a kid in high school. It all seemed so theoretical, so foreign. But now 20 years later watching these documentaries by Cox these concepts seem tangible, even beautiful like a painting. Well done! I wish we had more science teachers like that. People who can communicate these things in a hands-on manner. Music and art classes provide the intuition to understand context and connections as well. So the hard sciences and the arts (and sports) do complement each other.
Interesting. I found that for chemistry (since what was happening at a molecular level was rather abstractly related only to any experiments we could perform), but not for physics. We did little experiments regularly, practically modelling and testing whatever it was we were learning about at the time (well, except for a few things like radiation), and it was the hands-on link between theory and prac that I most enjoyed.
Unfortunately the physics you learn in school isnt all fun and games, rather it helps us solve earthly problems and make money. Thatd be amazing if it had even a little philosophy and pop science though, just to inspire kids even if they have to get down to the nitty gritty stuff first.
Yeah my physics class was trash too actually. Although it is entirely possible you as an adult now are well more rounded say Vs.. your highschool self :p
So maybe finding these concepts finally tangible is a result of that.
Anyone else notice he’s sitting in the room from the “Slow Rush” album cover?
Yessss
Strange that he's also talking about time, something the album does a lot of as well
haha i was wondering if anyone noticed that
OMG YEAH
Holy moly
This is why I always feel like nothing is ever as “perfect” or “designed” as it was first meant to be, once something is put into motion it will continue to degrade/ depreciate as time goes on, until a force is placed upon to change the current path
I love the way Brian Cox explains things in a way that just about anyone can understand.
Someone said to me "if you can't explain something simply, you most probably don't understand the subject enough". That's why Brian Cox and Neil de Grasse are definitely one of the best scientists.
All a load of tripe , next they will be saying we are descended from apes.and the only life in the universe 😂
speak for yourself I don't understand shit!
@@domantlen6231 Neil and Hawking have a way of explain science that makes it easier to understand. I love reading their books
@@brucedunn6845 both of those things are true as far as all empirical evidence would suggest.
His appearance discounts his own theory - this guy appears to be getting younger
his appearance has low entropy
This was uploaded 10 years ago...
Except it’s not a theory and it’s not his either.
I think its his big head, we all know time runs slower closer to the centre of a dense black hole.
This was 10 years ago lmao
"Now, let's gonna create some order in the Universe...". [Brian Cox]
Builds a sand castle...(1 second later)...British flag! Classic.
Lol
😁😂🤣🤣
United Kingdom flag. British flag is different.
@Tonald Drump aaahhh an idiot.....
@@deanmoncaster That flag is called the Union Flag and, by the way, it is upside down.
I've long heard the entropy explanation for why time only appears to move in one direction, but I often wonder if we haven't been looking at time altogether incorrectly.
We always seem to treat it as some mathematical abstraction, or some linear line of events, tacked on at the last minute to our understanding of the physical universe. But I've pondered the notion that perhaps time is actually _cumulative_ -- that it doesn't move or travel so much as it merely continues to add to itself, like an ever-expanding sphere.
I don't have the physics knowledge to be able to actualize this idea, but I know that time is already recognized as integral to the composition of space (space-time). I simply suspect it has more of a 'physical' presence than is currently believed. If so, it _could_ help explain the ever-increasing rate of expansion of the universe, what we now attribute to "dark energy" (which NOBODY understands).
its cuz time is a giant pit and theres nothing to stop us from falling further
Wonderful how he explains things so easily. One of the top scientists today.
The BBC really do make the best documentary's. the presenter, the music, the quality. this series blew me away. "Beautiful order" indeed.
HipFire_HeadShot agreed, but the flag is upside down, or is that entropy in action :-)
i spotted that immediately! well done
Yep quality work indeed.
That is why we must fight to protect its artistic integrity from the interference of petty fogging politicians who try and do it down at every turn - it is only one small step to Trumpism and one small stride from North Korean crack downs.
I admire the British for their artistic and intellectual integrity. (Aussie here.) Hopefully it always remains.
Amazing comparison of sand and wind to ultimately being torn down and reassembled into some other order. Aren’t we all at some evolutionary phase of entropy? Simply a fascinating conversation!
ya stoned
@@markroper6644 …
but enthropy contradicts evolution
@@cloud42269 if entropy is the involvement of things becoming more chaotic and random over a period of time and evolution is a structured order of all things over a period of time; could we not see this not as one over the other but both, merely separated by phases or portions of time?
No. The castle of sand was assembled by a human being who thought about it using pictures, models of castles, and direct of real castles that were engineered by at least one engineer and/or architect, all of whom had brains with minds that directed their able hands! Those brains and hands were in turn designed by a SUPER ENGINNER, AN ARCHITECT AND the BUILDER of the UNIVERSE! The wind destroys the castle, and the body of sand does NOT "reassemble into some other order! The sand just comes back to the original state of disorder.
He is one of the greatest teachers ever. And such a soothing voice… ❤❤❤❤ and so clear and easy to follow. A perfect teacher ❤
I watched this two years from now and it is already bending my mind.
the footage, the b roll, the cinematography, the music, and the explanation, perfectly shivering
Wow. Just wow. The production on this video was so immaculate. From the ‘sands of time’ theme all the way through to the incredible location (I assume it was shot in Kolmanskop, an old abandoned town in Namibia). It took time for YT to recommend this to me but glad it did.
It's almost perfect. Can i ask why do you think it's Namibia ?
@@skevakler There's an abandoned town in Namibia that looks a lot like this scene- empty houses filled with sand... it was the first thing I thought when I saw it too :)
thank the algorithm of recommended videos.
it is kolmanskop! the buildings match up, and i actually lived in namibia!
Brian Cox - you are the most amazing teacher I've ever heard. Thank you for sharing what you know, and explaining it so very well. I've always loved science even though it was not my primary field of study. What lucky students you have!!!
Never saw this before, although I did ALWAYS use another video of his in my classes covering acceleration, atmospheric resistance and terminal velocity. In it, he drops a bunch of feathers and a bowling ball simultaneously, from being suspended perhaps 20 or so meters in the air inside the world's largest vacuum chamber. They, of course, hit the ground at the exact same time. Great to watch!!
This is a novel and utterly (IMHO) perfect way to explain time's flow. Never have I seen anyone better define such an abstract as 'time' by explaining its simple adherance to the laws of Physics, and specifically Thermodynamics. It also proves the only other decent explanation for time I'd ever seen....that " Time is a measurement of change."
VERY well done, and Thank you, Professor Cox.
There is a problem with Brian's claim.
If increasing disorder creates the arrow of time then that means that time must reverse, every time entropy decreases and things get more complex. That include biological systems, evolution, human development and technology and that is clearly not true.
Another issue about entropy is that it was formulated by studying gases which are fairly unstable. Not by studying solids like diamonds that can maintain structure for huge periods of time.
@@Andrew4HandelAre you also a physicist?
Yes@@kfalla1
@@Andrew4Handel Impressive. I so admire the way your mind works.
@@Andrew4Handel Yes, if it is 'highly unlikely' that entropy will decrease, that means that it CAN decrease, and therefore that would mean that (very rarely) time would run backwards. Entropy is a measure (perhaps a symptom) of the arrow time, not its cause.
Watching this without sound, I just see a grown up man playing with sand.
same
Same
same
I see the sand playing with a man.
In slow motion at times
"Honey, are we really abandonding the house?"
"Yes, dear. So in the future a scientist can make this area a good example of how to explain Entropy."
Wonders of the universe, my favourite tv show ever, I never missed an episode of it . Thanks professor brian cox for igniting my interest in space .
This is the single most understanding, easy definition of what entropy really is. I never understood it in high schools, so cool!
Same here. For some reason I struggled with the concept of entropy at school. This taught me more in 5 minutes than hours of classes did.
Well , according to Brian , it was inevitably going to become cool , sooner or later. 😉
Wow, I truly like this guy. My dad says that when a person knows something they are able to explain it so that anyone could understand. They don't need fancy words to make others puzzled, but they can make things simple. And this guy here knows how to do that. It means he actually knows what he is talking about.
Ur dad is stupid and so are u
The quote you are looking for is "If you can't explain something to a six-year-old, you really don't understand it yourself." - Richard Feynmann
@@gpr1016 Thank you xD
@@gpr1016have you read his work it a little bit beyond a six year old..
I believe he was actually referring to his diagrams
This is explanation of entropy not time
You might want to look up the concept of arrow of time.
Time can be expressed by measuring a difference in entropy. The big bang had low entropy, yet now we have much higher entropy and it will continue to increase... Or something like that
Time doesn't exist, if it does, then it's merely a scale we use to measure the process of low entropy ==> high entropy
Almost had a stroke reading this small thread but I think I get it
en.wikipedia.org/wiki/Arrow_of_time
Its the same thing.
Best and clearest explanation of the 2nd Law of Thermodynamics I've come across! Well, done! Brian Cox and thanks for being such a great science teacher!
I think we are missing the second and most crucial part where Brian explains exactly why the 2nd law of thermodynamics demonstrates why time travels in one direction !
Tim Marchant BS
It demonstrates why time appears to travel in one direction for us, not that from every perspective or under ALL circumstances that it does.
I travel in one direction. Sometimes forwards, backwards even sideways! Never all three at once.
I agree 100%. A great explanation THAT time travels in one direction but no how and why to go with it. If this is related to the expansion on the universe then he needed to mention it.
I love how most shots of Brian Cox, could all be great album covers 😅
I mean he was a rock star
@@meetaverma8372 in more ways than one 😉🤤🤪
His hairstyle from one direction
More like justin bieber
😂
Needs more likes
He had that hairstyle when the one direction guys were still swimming in daddys' ball soup.
One direction what?
Your sentence makes no sense.
what a beautifully shot and explained film. I remember watching this with my father when I was little and remembering the profound impact it had on me, Im glad I've come across this video to remember me of those times.
Wow I got recommend this 10 years later, but I am not mad. I revel in knowledge and love to learn. Not to mention Brian Cox voice is so soothing and just facilitates my ability to learn by demanding all my attention without suggesting it as in yelling at me to listen.
Brain Cox , I am your fan. I saw your series on BBC a decade ago, since then mesmerized.
Time and space are intimately linked and the progression of time is relative, not absolute. There is nothing in physics that says time must flow in a certain direction. Space can also be folded by gravity; therefore traveling back in time is possible if you can fold two ends of space together, ie., the beginning and end of any distance traveled.
It could also be be with the death of the universe entropy falls back in time 😐or if it does not 😐time always goes forward then eventually leading to a new universe if you think about it the universe had very low entropy😐after all I have realized the universe could have some determinism to it as well after all we could have Ben anything or anyone so why are we human 🤔in specific points if this planets history 🤔it seems off 🤔
the bending of light in the presence of colossal gravitational fields leading to wormholes.
I always feel more at ease with death itself when I listen to Brian Cox. I guess it's just the way he calmly explains how this all fits, and how it's all good, even if our brains struggle with the unknown...especially death.
By far WoTU was my favorite of the Wonders series and my favorite "science/physics/space" documentary ever. I really would love if they revisited the WoTU episodes and did new ones with updated information.
Fantastic lesson as usual. I don't know if Brian still works as a lecturer for a University at all but if he did, I'm sure he would dramatically raise the uptake, retention and pass rates, easily! It would be brilliant to be part of a "live" lecture with him guiding the ship.
He lectures physics at Uni of Manchester
@@MD-ji2ct oh great, I'll sign up for a course then !
Ticking away the moments that make up a dull day, fritter away the hours in an offhand way
Kicking around on a piece of ground in your home town, waiting for someone or something to show you the way
So you run and you run to catch up with the sun but it's sinking
I have studied Thermodynamics in University Science, and Engineering, and this is the best explanation of Entropy I have heard. Well done!
Yes, everything is moving towards entropy. Moving towards change. Everything changes along the way. Everything...
Nothing escapes it. It doesn't matter to what it changes to, it just does it.
Our lives are nothing but matter changing within the movement of the universe. We assign a numerical measurement "time" so we can understand the movement of entropy. Brian explains it very well.
The order and speed of matter's movement at the universe level is in one direction and that direction is to total decay of matter down to the smallest parts of matter. At this time of our knowledge, down to the quatum level. Then the question is, "where does it begin to reassemble?"
If you go to 0:30 and take Brian Cox out of the image, you’re left with something incredibly similar to the artwork for Tame Impala’s album ‘The Slow Rush’...which is all about time 🤔
nice
Incredible spot
Uuu1qqqqqw❤😂🎉🎉🎉w 🎉🎉😂hu 🎉😂🎉w r 🎉🎉k w🎉😂🎉😂😂🎉w😂😂🎉😂🎉🎉😂😂🎉😂🎉🎉😂😂🎉😂🎉😂🎉q😂😂qq😂🎉😂🎉q❤😂😂wywtya🎉
You can hear the happiness in his voice.
This is by far the best explanation of entropy.
You should watch "Entropic Time" by A Capella Science.
And he is really singing backwards. 😆 There's a making of video for it.
Brian Cox: "For now let me create spme order in the Universe."
- Introduces a colonized sand castle
lol
Piss off snowflake
haha great
Yes time only runs in one direction, from past to future. You cant go into the past unless you have a camera and you can record moments of past and see them in future. That's the closest we have come to time travel. Otherwise tangibly its impossible to go from past to future or future to past because you will disrupt the very laws of universe. Thus time travel is impossible and time runs in only one direction. Time travel is only a myth and fictional.
@@GeekRaj time travel to the future is possible... To the past is still a bit debatable..
There are ways which we can use to achieve this... We might need tonnes of negative energy, or stuff like that which might be very hard to gather, but it's definitely plausible
8 years and BBC still hasn't fixed the title of this video. Lmao. I learned more about sand castles than I did about time.
They don’t need to. Entropy is why time travels in one direction.
i like sand castles ~(^..)
I dont get why you don’t get it. The total ammount of disorder in the universe which is measured by entropy always increases with time. So time moves only in one direction! Into a high entropy state of the universe.
@@majdsafa4009 Because he has reached the limit of his understanding. Some people simply can't wrap these advanced ideas or concepts arround their heads. I'm not criticizing him or insulting him in any way, shape or form. I'm just making an educated guess, because he is stuck at the analogy with the sand castle, and can not see beyound that.
Well that is because you are stupid
Everybody needs a bit more Cox in them. Love his explanations.
I don't need more Cox in me.
@@noahway13 I dunno... maybe you could fit one more.
I totally agree . Beause according to thermodynamics,time only flows in one direction . For example , a glass falling from the table and breaking into pieces represents increased chaos in the system.
Feels like the wind has blown these sand particles into a TH-cam Algorithm Sandcastle!
no one makes docos like the beeb, they really are the best.
Adam Ryan agreed, although channel 4 do a lot of great docs too.
how concepts should be taught in schools... simple, clear cut, easy to understand
I wish that everyone spent a bit more time watching and learning about these things, instead of dedicating so much precious time to mind numbing social media. Motivation, education and dedication can change the world. Thank you Mr. Cox.
Bud, this is edutainment don't get it confused. This does not enrich you in any tangible, usable way.
@@BobrLovrAnything that causes curiosity is enriching in every way possible. I am sorry that you cannot see that.
@@BobrLovr what a dumb comment
It's hard not to smile when Brain speaks to you with such a smiley face. yeah, science! :D
You mean that cheesy grin that says I know better than you?.....yeah great.
He seems childlike in his excitement and love for the subject
@@andyw2244 He does know better than you.
@@joshrkessler That's what he wants you to think.
Hello fellow 2020 survivors. The algorithm has summoned us here today for literally no reason. Have a good day
I would say 2021 survivors but we don’t know that yet 😳😳😳
To be fair, for some reason, at twenty to 6 in the morning, this came into my mind so I'm here.
The professor has entered my dreams via the flow of time to get me here, odds on
This is the man that got me interested in science and physics. Just watching his shows has pretty much defined how my aspirations have turned out. And now I plan to study Physics in higher education. Prof Brain Cox, legit cool dude.
'Apologies in advance for pedantry but words do matter, particularly when it comes to the understanding of scientific ideas. Brian Cox describes entropy in terms of being able to re-arrange the grains of sand and still keep the sand pile the same [shape]. As a non-scientist, isn't this contradictory? If something has been rearranged then it is, by definition, different. Also, around the [4:52] mark Brian states entropy always increases because it is overwhelmingly more likely that it will. That is fine as an observation but as an explanation it doesn't tell us anything as it sounds circular, as in "Entropy increases because it does."
What Cox is saying is that of all the trillions of ways that sand grains could be arranged, there are far (far) more arrangements that form a bell-shaped pile than that form a castle-shaped pile. So every time the grains are randomly changed you are most likely going to see the the sand grains arranged to become more and more bell shaped.
In other words, entropy increases because there are more high-entropy states than low entropy states. So, every time a system is randomly changed from one state to another available state, the new state is probably higher entropy (i.e., entropy is likely to increase)
Also, there is a maximum entropy and as you get closer to that maximum there will be little meaningful change to the shape the sand creates from one state to the next. Once bell shaped, rearranging the individual grains of sand is unlikely to change the bell-shaped. The locations of individual grains of sand can change a lot without changing the bell-shape( i.e., there are trillions of arrangements of sand that produce the same bell shaped pile).
I was with him up until the very last sentence. I lost him there 🤯
Yeah some more time on that would have been good. Presumably it's along the lines of, when you age & die your body might decay & be dispersed in many ways but the probability that it will reform as you with the spark of life is not equal to all other options, therefore it goes forward but not backwards?
I'm guessing that's the inference, but it seems separate to why we wouldn't walk backwards & talk & think backwards - if we did we'd be unremembering so we wouldn't know we were - but we use gravity to walk (fall forward) so there's that, but it still feels only half answered.
Thank you for explaining entropy that way. I thought I understood entropy but I now know that I didn't. Now I do. Thanks!
At the end of the day. It is night.
Ive hated anyone in real life who has ever said that
You would be best telling that to someone who actually gives a shit. @@mikec4308
Wrong,end of the DAY is Y!
Yes. Y. I ask myself that at least one every three or five days Y.
This was a better explanation of why time dont scoot both ways then this video 👏
I'd really like to think that Professor Cox is having the same effect on this generation as Carl Sagan had on mine. His enthusiasm is contagious, and I could listen to him all day.
My 5 year old son now thinks the wind can randomly make sandcastles by blowing sand about!
+Neil Thompson now "knows" that wind can randomly make sandcastles by blowing sand about 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001% of the time ;)
Well, he's not wrong though.
I may not remember this correctly, but the wind has difficulty creating a sandcastle because the energy of the wind is incoherent, in the same way ambient light, also incoherent, doesn't cut us up like a light saber. Coherent wind, in the form of a air gun maybe, could blow the sand into a smooth wall on the north side, then move to the south side etc. etc. until the shape of a sand castle is achieved. This however requires an expenditure of energy beyond the energy of the wind to focus it's power. Coherent effort, in the form of the mold and the worker, creates a sandcastle faster than random wind.
Gordo Hogo,
it's more or less that. It's related to the concentration of energy of the wind: the energy per unit area. Building a castle would require just the right distribution of energy concentration in the wind, which is why it is highly unlikely. Coherent wind, such as an airgun has high concentration and thus can be directed in order to distribute its energy to the sand in the right way. Incoherent wind has a more even distribution of concentration, and for a given amount of energy, the concentration of an incoherent wind is much less than that of a coherent wind, so it cannot easily be directed to form a specific shape.
Statistically speaking, an even concentration distribution is more likely than an uneven one, because if the distribution is uneven, the energy will flow until the distribution is even (like heat). Things with high entropy like the sand pile or incoherent wind have even but low energy concentrations, which is why there are so many ways of making these things and why they are much likelier than their ordered, super concentrated, alternatives.
leedsmanc which freak parent would show this to their 5 yr old kid?!
I think it's also important to point out that our observational understanding of time is borne from us operating as biological structures that survive in a world we're time appears to flow forward and every significant thing we interact with seems to be doing the same. . "The Order of Time" by Carlo Rovelli is a great book 😊
Yea but it could be that time is just an illusion 😑after all what do you remember before you were born ? That’s right nothing 😑nothing but darkness if you can’t even remember events before the day you were born what makes you think time had a beginning? 😐you were all ready dead for who knows how dam long 😑your mind can’t accept it beacuse your alive 😐the truth is the universe could be indefinitely old it’s just or brains can’t handle it 😑you have to think before you were born before earth before the soylar system before the milkeyway before if our milkey way is part of a merger or not and you have to think about the previous galaxies and galaxies That came before those all Those planets stars etc you would have no idea and before those galaxies ever came to be before who knows what else and even if the universe is finite you would have idea what caused everything to begin with and what happens before the moment of creation 😑this may be to much to your brain to handle 😐it’s just that you don’t realize it
This video has travelled 10 years through time to meet me and you 🧐
TH-cam algorithms working overtime
What are the odds huh 🤔
A compelling way to ultimately explain death and the universe. Before we are born we are nothing but atoms, we then exist as a being with low entropy form until one day we will have the same high entropy form as ash before returning to nothing but atoms. Its simultaneously beautiful and terrifying to think about.
Brian Cox is going to have a lot of explaining to do once I've finished my time machine.
If you ever finish it, then you will have already finished it.
meanwhile, someone in the distance watching him:
"Is that Shaggy? why's he making sandcastles in the middle of a desert?"
😂😂😂
Jimi Hendrix - 'Castles Made Of Sand' explains entropy a bit better, but you need a good cup of mushroom tea to decrypt the lyrics.
Rob Fraser I tried it with acid a couple of years ago and his music seemed so avant gardè
Ahh, shroomie tea. Good times.
If Brian Cox can be a professor waffling on about his unproven theories( won't even go into global warming) what degree should Jimi Hendrix have received playing and singing the most amazing music ever in the Universe!?! Ok , in our galaxy.
I love using the 2nd law of thermodynamics and entropy to explain some moral issues and enforcing values to my students. For example, it is easier to do bad things; it is hard work to stay good. That is because to decrease entropy of a system (towards order due to doing good things), the surrounding (including my students) must exert work towards the system. This will increase the entropy of the surrounding (muscle breakdown, consumption of food molecules, etc. due to excertion of effort, use of resources and energy). Another way of stating this is, it is easier to make a mess of my room than to keep it clean and organized.
Goddammit, one of these days I'll understand entropy if it kills me!
Clever!
Shadow Heart it's best if you don't, everything he said was irrational
From what I think I've gathered from this video is that the amount of Entropy an object has corresponds to the likelihood of it's particles forming the same structure when rearranged. I'm sure it's much more complicated than that though.
Cox and Greene often make elaborate analogies to describe their theories, making their books (and videos?) annoying to read.
I don't know if I can do much better but Entropy is the 'degrees of disorder' in an isolated system (eg. Universe) and is goverened by the 2nd law of thermodynamics which says generally* that chemical/physical processes always occur (spontaneously) from a state of order to disorder over time always *increasing* Entropy towards thermodynamic equilibrium.
Understanding what Entropy is (as you hope might kill you?) is fairly straight forward. As I said above it's just the state of disorder in a system. The example of an egg (high order, low entropy) is often used. If you break that egg (low order, high entropy) it's impossible to restore it to it's previous order. Pouring cream into your coffee will spread through the cup (higher disorder [Entropy]), you'll never see it clump up in one highly ordered region of the cup ... and other innumerable irreversible natural processes (which the second law can now explain the nature of this asymmetry).
As a consequence of the second law of thermodynamics definition that the total entropy (of an isolated system) is *always* increasing (including the Universe itself, it's far more disordered now then when it began) an asymmetry between future and past must exist because ... it *only* increases over time, it can never decrease so we know time has an arrow (only moves in one direction) and can actually use Entropy as a *very rough* way of distinguishing something from the past from the future.
He basically just took 5:30 to explain what the second law of thermodynamics states instead of just using the stupid egg example I gave you (and that all teachers have used for decades) or any simple irreversible natural process and there's really nothing to explain short of 'things happen asymmetrically (towards higher Entropy) over time (cause and effect) so time itself is asymmetric (has an arrow or 'direction').
*There's a ton of math shit, I'm just giving you a quick answer, Entropys' quantity (S) is formally defined as S = kBlnΩ and ΔS = δqrev/T
Shadow Heart I've just realized the joke... lol
The title of this video seems misleading.
His answer might as well been "Because it does."
@@ikilledthemoon Yes, if time ran backwards... it would be the opposite. Hardly an explanation of the arrow of time.
@@MaskOfAgamemnon You're asking the difference between positivity and negativity; there is none, because it's a matter of perspective. An example:
An electron is negatively charged, and a positron is positively charged. If time ran backwards it would NOT be the opposite... It would be the exact same as time moving forward if we replaced all electrons with all positrons, and all positrons with all electrons, or didn't change their charge at all. Charge does NOT determine the arrow of time. Look into Charge Parity Symmetry if you want to know more. Basically, physics must work the same whether time is going forward or backwards.
Entropy, on the other hand, DOES determine the arrow of time. Entropy is a phenomenon that is less binary than +/-, because it has nearly infinite values in between order and disorder. It just so happens that what we observe is that disorder is the probabilistic state of the universe. Look into bifurcation theory if you want to know more.
Cox even explains, "the sand in this pile is equal to the sand in that pile." So, you're fundamentally looking at the explanation wrong, it's not that the explanation is wrong.
Imagine a box, with 50 particles and 50 anti particles. If two collide, they annihilate. Entropy states that, over TIME, the box will be EMPTY. That's it.
So, it doesn't matter if we start with 50/50 particles, or if we do the opposite and reverse time so we start with 0/0; you'll always end up with 0/0, an empty box.
Entropy prefers disorder, regardless of if the system was in order or disorder to begin with (the only thing that would change if you reversed time)
@@MaskOfAgamemnon Think of it like this. You have an x and y, x is time and y is what is happening at that time. For example, like a birthday, there is a specific time and date(x) for a specific event(y). So you have a linear timeline of events, whether you move forwards or backwards( no paradoxes involved). Think back to the sand castle imagine yourself watching the wind scatter the castle back into the desert, like expected. Ok, now take the same experience, and make time go backwards. What you see this time, is that the scattered sand will gather to make the sand castle, something highly unexpected. So what can you conclude from this? That time has to obey the laws of entropy because overall, entropy is always increasing as time moves forward and by going backwards in time you are breaking the laws of entropy.
@@danieldelgado399 so linear time is linear? QED, where do I put your name in for the Nobel?
@@MaskOfAgamemnon yes, quite silly explanation. It’s more like entropy has to obey the linearity of time than the opposite (if we need to make that meaningless relationship)
I gotta stop watchin this mf while I’m high I be wantin to quit my job and study stars and shit and also Brian wth you in the damn desert for anyway you know they got sand at the beach?
Yeah, I’ve wondered why he had to go all the way from Manchester to Namibia to explain that when he could have just gone to the beach at Blackpool.
Come to think of it, if you want to see entropy on a human level, Blackpool’s bloody perfect.
You're an actual cliché with the way you're trying to sound when you talk/type 🤢
This is the cringiest comment I think I’ve ever seen.
Your picture shows a white person but .... uuuummmm?
Like .. stars and sheeyt. Init
I could spend all day listening to Brian Cox. Brian Greene is another great one to listen to.
Is this the set of Fallout?
As an engineer and having taking a lot of classes, I dealt with entropy in Thermodynamic and Heat Transfer classes the most. I always used this simple example to describe entropy: You can never unscramble an egg
Feed it to a chicken.
My high school best buddy --and later in college too--used to have talks with me like this. He knew I didn't understand the math or the physics, and if I added anything to the conversation he'd go along with my childish thoughts and compliment me. Unfortunately, he's become a radicalized political ideolog and I can no longer have even casual conversations with him. Extremely intelligent people seem to go this way often, and it is such a gift to have a genius like Cox stay so plainfully down to earth. Thanks for posting!
Brian Cox is the Carl Sagan of our time, and I am privileged to be able to listen to and watch him explain science.
He is a breath of calm in a world of chaos(entropy).
So - why does time goes only in one direction? Because entropy tends to rise. Why? Because it it overwhelmingly more likely to do so. Thanks Brian, now it is absolutely clear!
It is a very poor title, he doesn't do anything to link the two concepts.
Amazing video, very informative, and Brian Cox explains the subject in a very comprehensible way. Thank you.
A perfect explanation
I know this might be outdated now (4th of December, 2024) but he was a massive part of my childhood and I will watch him forever.
Excellent simple video explaining entropy, Brian has an amazing skill.
So after watching this video (3 times!) I'm assuming that the transition of low to high entropy is the natural process of most interactions?
If this is the case then how are low entropy states formed, are they the result of high energy?
In regards to time reversal, I'm going to assume that every entropy transition process is impossible to replicate because of the complexity involved. Put simply it can happen but it won't.
I'm not an expert by any stretch but I believe that low entropy states are the occurrences of the extremely low probabilities which Brian is talking about here. If you consider the entire universe to be the sand castle it can be imagined as one entire system moving from low entropy (high order) to high entropy (low order). As for why the universe began with such low entropy, we don't really know.
Brian Cox.. looking like he’s about to star in video for Tame Impala’s The Slow Rush. Coincidently, its subject matter is about the passage of time.
Plus he was in a band himself so he probably knew that lol
Mad I was just thinking the same when the light was coming in the window.
Very nicely, very impressive.
Entropy was my most favorite topic in physics way back during my 12 grade time/ around 40 years back, and still I am fascinated by the simplest idea leading to such a huge understanding ....
Funnily enough, I'm in 12th grade as of yet and I, too, am fascinated by this concept haha. Just watched some videos to understand it more.
Sandcastles are overwhelmingly unlikely to form in the wind - this makes me really appreciate how overwhelmingly unlikely and precious structured creations like humans are
mmmm.... so just realize there is a major difference in those two processes. The sandcastle is just a placement process where relationship between the component parts is effectively independent of the other parts save the results of collisions due to shape and what not... whereas, the organic chemistry of life and the biological components that support it are very exclusive, very precise, and depend on finding the lowest energy state possible in terms of conformation of the molecules and the atoms/molecules involved. In other words, there are nearly uncountable ways to organize sand with sand, but in the case of chemistry, there are far less ways, and the system will find it's lowest energy state by itself, which is why chemistry is a predictable and understandable science. From a distance the complexity of a human seems unfathomable, but when you zoom in and look at a specific subsystem and how it works and it's small chemical structure and function, you see a repeating pattern of being in the lowest energy state, departing from it due to a specific interaction/stimulus, and then returning to that same lowest energy state. All these simple operations summate to a complex system, but the parts are simple... in the same way an economic transaction is simple, but when aggregated into an economy, they are not, and yet the whole complex economy is still reducible those same simple transactions.
@@jonc5152 And where does consciousness fit into this? How would you define its chemical composition? This is not a rhetorical or trick question.