The fluency and clearness in they way he talks is perfect.It makes those who don't have a physics background help get a grasps on these fundamental ideas. As can be said about all the other talkers on sixtysymbols, and Brady's other channels. Bravo.
Brady, I love what you have done for us here with all these channels. I don't think I've ever learned as much as when you interview these brilliant people. And your way of asking questions just shows what a great view of life you have and how you really burn for these types of questions. These channels are my go-to place whenever I need a thoughtnugget, thank you so much for doing this for us!
I love the explanation. Also I love the equations on the board in the background. Details like that can make one feel a lot better, and contribute to a video's quality.
Please tell Sean that he needs to narrate a documentary at some point in his life. He is so good at explaining things and I could easily listen to his voice all day!
What makes these videos damn awesome is the fact that Brady always asks the questions the rest of us are thinking about. That's why I love these videos and think that these are more educational than many straight up explanation or teaching videos of the same topics.
I left a glass of water on my bedside table last night and when i woke up there was ice cubes in it. Forgot to say I went to sleep outside at the south pole...
I could listen to Mr. Carroll talk for hours. His mannerisms, speech patterns and inflections make him very interesting to listen to, while his explanations are well articulated for folks who haven't a clue what he's on about going in. He makes complex subjects easy to listen too, and hopefully learn a little from.
what an incredibly enriching chat! this channel is a goldmine for the mind, this should also find itself featured on the front page of youtube alongside of all the banal content.
Great video, a very clear way to explain the systems we have to use. Although as one of my 1st year students pointed out to me before. The pendulum does slow down.
By the way, thanks for being probably the most insightful and broad-ranging youtuber there is :) Keep up the awesome stuff, you inspire alot of people to take up particle physics, mathematics, etc. through your videos.
It means that your brain is attempting to move backwards in time by organizing information, while the universe is moving forwards in time by disorganizing that which began in an organized state. We are trying to remember what the universe has forgot.
Really nice question!. However, as time is basically interaction, if nothing occurs before the big bang then there is no change in space. If there is no change in space, then as spacetime is inextricably linked, there will be no change in time, and thus no direction to it.
I gotta look that up in that case! In the few videos he has been in on sixty symbols he's starting to become one of my favorite "stars". The way he explains things is extremely clear and always spot on. Enough detail to keep it relevant and correct, but simplified enough so us normal people can understand it in one go. Quite honestly I'm baffled after every video with him in it. Such a smart and inspiring man to listen to.
As about 12 people have mentioned before me, Sean's voice is great. The topic/discussion was great too, but there are lots of those on this channel. Sean's voice stands out notably.
Andrew Tofelt Was that in Hitchhikers? It does sound like Adams. That expression has been used a lot on Doctor Who. I think the first mention was with the introduction of the Weeping Angels.
Except it isn't. You can measure time, it can be defined by other physical quantities, and you can measure its effects on objects. It is antithetical to metaphysics.
Stop with your nonsense word plays, there are no measurements within metaphysics, there is with time; there's a huge distinction between the two. So yes, I suggest you stop repeating idiocy without conscious consideration of what you're saying.
No problem. The point to take home is that, other than our own memories, entropy defines events that have occurred earlier with events that have occurred later. If you look at two different photos of the same event, the one with higher entropy can safely be assumed to have taken place later in time, such as a glass of water occurring later than a glass of ice, a slower pendulum occurring later than a faster pendulum, etc.
I don't believe in an 'arrow of time'. I believe that time is just like space, it has no natural direction in which it progresses. The arrow of time I think is an illusion created by the fact that we remember our past and not our future. This gives us the illusion that we are progressing in time and essentially moving from our birth to our death at a fixed rate. This rate would be the speed at which our brains process information and turn the information into short-term memories. I believe that all our versions are existing and real, just as real as a third spacial dimension is compared to the second. Only those versions have different memories which makes each version think it is progressing in time. This is a really interesting way of looking at the difference between the world the way perceive it and the world the way it actually is, with 4 dimensions rather than 3 dimension of space and 1 progressive time dimension.
There is still the question: what is it about that fourth dimention that make any given version of us remember things only in one direction and not the other?
+Ariel Rile Well, quite. The comment seems to be saying "I believe the arrow of time is an illusion caused by the fact that the past and the future are different". It's a bit like saying you believe gravity is an illusion caused by the curvature of spacetime.
I'm another 3+1 dissenter who believes time isn't unique amongst the dimensions. I'm not with you on the many-worlds interpretation, but I'll help you make your case for 4 dimensional space... Let's start without a reference frame. It is impossible to say how fast objectX is going, the rate of its clock, how compressed it is in any of the spatial dimensions, or its mass. But, objectX has itself as a reference frame. We can now say objectX has no movement in space, its clock runs at full speed, it's uncompressed in all dimensions, and has mass of X. Pick any other reference frame, and things start to change... The subset of possible reference frames that see objectX as moving arbitrarily close to c is still infinite in number. The universal constant is a ratio of space to time, but thinking of it as a speed gets the numbers right, but misses the point. It's a ratio of equivalence. One second=186000 miles
Covalence Dust radioactive decay is and example of single time direction. They never gain neutrons. The basic cycle from H to the heavier elements shows the natural world we exist in is omnidirectional.
In the video "Relativity Paradox" on this account, simultaneous events can occur at different times. If the trainspotter was on the end closest to the entrance then the train would first see the guillotine come down, and then see them press the button after the train was through. By changing your momentum you can alter time in the area around you as well, until you stop accelerating and move at a constant speed.
Great video! The most awesome is the idea of comparing time and space - "space has `arrows` when near a big body" and "time has `arrows` when near a big event"
Another related question I have been wondering about: a lot of scientist say that the universe is infinite in the spacial dimensions, while the dimension of time is finite (big bang till what ever ends it). So why can those three dimensions be infinite while time is limited? Or is that just the illusion created by macroscopic entropy, and we just can't observe beyond the low entropic origin?
I really dig Dr. Carroll! I could listen to him talk about physics for hours (and have thanks to a number of talks available on UA-cam!). Make sure Brady you corner him every chance you can get! And keep up the excellent work. I would like to see more 60 symbols videos (as much as I like Numberphile I love me some physics...)
Could photon energy form the process we see and feel as the flow of ‘time’ a process of continuous energy exchange or continuous creation? With light being a wave over a period of time and a particle as time unfolds with each photon electron coupling. The electron is the most spherical object in the universe so this can form the low entropy for the increase in entropy that we have in the Second Law of Thermodynamics.
Some similar thing bugs me about time. R. Feynman has described, for example, that positrons can be thought of as electrons moving backwards in time. Some interactions in the diagrams show parts moving backwards in time. So do physicists actually still think that some particles move backwards in time? Is that a physical reality? Or just a convenient way of thinking about it?
Could the Fibonacci sequence be formed by the spontaneous absorption and emission of light? All the info I can find says that this process is formed by the quantum wave particle function Ψ of quantum mechanics. When this is reformulated as a linear vector ǀΨ (t) > the two previous vectors are added together to form a new vector this forms the Fibonacci sequence 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ∞ We will feel this process as the arrow of time within each reference frame.
Now an interesting question: how come you're moving down that river if there's no time? You need at least one variable to be constantly changing for there to be motion at all rather than stuff just being there, but if time is fixed then that variable is fixed as well.
Yes there might be, see "heat death of the universe", for example, on wikipedia. But as the article says, there's lots of speculation going on. I just got curious about entropy in the big crunch hypothesis, where the universe ends in a black hole. Black holes have massive entropy (because they the decrease entropy in their environment), but how could it possibly start a "new big bang", where low entropy is needed?
Could time is an emergent property with an Arrow of Time for each individual reference frame with the future continuously coming into existence photon by photon? The quantum wave particle function Ψ or probability function of quantum mechanics represents the inward absorption and outward emission of light with each new photon electron coupling representing a new moment in time within that ref-frame. Photon energy forms the process we see and feel as the flow of ‘time’
Time can move in any direction. It's not a question of "which way it's going," but rather where the system is going, what direction force is being applied, where heat is being released, so on. He did say what direction it's going in - toward entropy. And I believe it was an analogy, the astronaut - and a 'relatively' good one.
I've heard an explanation for the arrow of time that goes something like this: You can only observe increasing entropy because increasing entropy is the only way to disseminate energy that can be observed. It may be that time goes in both directions simultaneously, but we are unable to observe the reverse evolution of the universe. If you were to reverse the scrambling egg, you'd have to reverse the molecules that formed the memory of the egg ever being scrambled in the first place.
Can you do a video on how the thermodynamic arrow of time relates to the psychological/documentary arrow of time; i.e. we can remember events to the low entropy direction of us, but not events to the high entropy direction of us, and we feel that what we do now can effect events in the high entropy direction but not the low entropy direction?
A proton travelling backwards in time would still have a positive charge, it's +1 charge comes from the sum of charges of the two up quarks and a down quark that make up the proton, the fact that it's travelling backwards through time doesn't necessarily convert the quarks to anti-quarks. Just my guess, but you might want to check that up, it's a good question :D
Professor - look into the discussion of time in St. Augustine's Confessions books ten and eleven. I don't remember whether he considers the arrow of time but he has some surprisingly modern-sounding ideas about time and human memory - back in the 400s AD.
There is something I never understood about thermodynamical arrow of time - there is slight probability that some unordered system of, say, gas molecules at some point creates low entropy system, like all particles being in one corner. 2nd law says that, somewhere else, entropy increased so that total entropy increased. But how can we be sure?
@sixtysymbols, I think you guys should have an online physics/mathy competition for those aspiring physicists(myself included) to win a trip to view Nottingham and meet the professors! or just a prize or something, but that would be really cool.
in addition to or instead of the entropy factor, I wonder if the many worlds interpretation of QM is a quality of the directionality of time. if universes split into multiverses as time goes forwards and as entropy increases, do separate universes re-merge into one if entropy decreased with time?
Starting at the level of an atom with its electron cloud surrounded by vast other clouds of uncertainty but each with probabilty and when acted upon a definite arrow has been created and entropy is in action. I am curious to know how the probability clouds allow time to propagate and the variances in possibility outcomes .
The Law of Conservation of Energy puts a lot of rational consideration toward the initial, low-entropy levels of our early Universe. Before inception, no energy was being transferred - you could call the 'time' before that event a Universal Ground State. There were no systems in place to attain to the Second Law of thermodynamics yet, yielding no entropy. It increased as systems were introduced. Brady, you're right about a lot of the questions you ask. Many of our assertions hinge on semantics.
Thing that puzzle me… If the arrow of time begun at lowest entropy (Big Bang), why Universe preferred current direction of time dimension versus distribute on both directions from point of one lowest entropy towards two directions to highest entropy. With analogy of space-dimension astronaut, he is pulled to Earth same as some other astronaut on opposite side of Earth. Space-dimensions doesn't prefer one direction over other.
I'm not sure but given the statistical definition of entropy is Maximum entropy=Log ( Number of micro states of the equilibrium position ) I'd assume it depends on how much stuff there is in the universe and how big the universe is. So if the amount of stuff in the universe is finite and so is the universe itself, then so will the number of micro states which would be possible would also be finite and so there would be a maximum value resulting in maximum entropy. I think.
So if we started off at the Big Bang with the lowest possible entropy, when the process reverses and we get nearer to the Big Crunch, does that mean entropy will decrease and things will become increasingly predictable??
Very Interesting video, as usual from sixtysymbols, thank you! It did however somewhat strike me as odd to say that Aristoteles didn't give time much thought, when in fact his fourth book has four chapters devoted to time. Sure they were not the last words on the subject, but there were some serious philosophical fundamentals laid there.
Was Sean Carroll on the BBC documentary about Feynman that was on the other week? As i was watching it i recognised his face and voice but couldn't put my finger on it...
I was expecting it to be something like that. But isn't it possible for particles to collide/change their momentum without emitting any radiation (or for example entering orbit around one other because of magnetic,gravitational or some other force)? Or does any interaction between any two particles by some law of physics requires that the new state is always lower than its previous one forcing entropy in any interaction there is?
I just find it so interesting that even the most involved theorists and philosophers etc in the end choose to live their lives as we've always done. It's the greatness of everyday life :)
Continue to: Time is an abstract that represent movement in space. Each movement of an object* is a reaction to interaction with a force, and each interaction of an object change one or more property of that object, we can look at entropy as an experience point on an object. * An Object can be the collection of objects or the single object. That said, a collection of objects can hold varied level of entropy.
I recently read his book "From Eternity to Here". It's really, really interesting, and if you have any sort of questions about this stuff it's the one book you need to read.
There are some situations such as air conditioning that would seem to decrease entropy (by making heat flow toward a higher energy region), but when you also consider all the energy expended to power that system you'll find that it more than negates the decrease in entropy. In answer to your question, we call it a "law" because there are no known exceptions, if you find one please tell me :D
Ok. I have one problem with the equations being reversible meaning that time is also. Let's say two particles travel on a collision path with each other and after collision they join up and fly in a direction that's the sum of the two directions. If time was reversible what would cause those two particles to split? There would be needed some event that would make them split, without such event we just have reaction without any action.
he is talking about an ideal pendulum, which would swing forever with no air resistance or friction at the pivot. which can be used as a useful analogy for particles confined to small spaces.
I got obsessed with time when as a 5 year old during a persistent unpleasant experience I realised that time would pass and when it passed it would be as if that unpleasant experience only existed in an infinitesimal moment that had was now gone. This is of course more about my experience of time, not necessarily its nature.
I understand time as happening of events. Processes are going on and we can see some changes and hence we can consider it as a flow of time. But do any events happen with atom? Electrons are circulating around the nucleus but how Sean has pointed, such simple system can't be determined as moving forward in time or backward. So does it mean that every single atom doesn't influenced by time and namely, time doesn't happen for it. And does it mean time happens only for complex systems?
That spontaneous splitting is quite interesting. I'd put my money on instabilities within the particle energy waveform that accumulated over time, and I guess this would also be a good reason why two particles would split when going the opposite direction.
Objectively, I don't think Professor Sean Carroll is any better (,or worse than the others of the professors, although all are GREAT,) than the other professors here at sixtysymbols, but I feel that somehow, his slightly deeper voice and casual way of talking conveys a greater meaning of facts. Again, I'm not questioning the skill, nor knowledge, of other professors, but... aww man, I just enjoy hearing him talk. Unless you have a factual objection, please don't correct me. Have a nice day. :)
Of all the people featured here, Sean Carroll is one of the best at communicating clearly and precisely.
trefod It's not really a fair comparison because the others are teachers so they aren't really used to trying to explain new information to people.
Jacob Estes Oh You! :D
+trefod I wish Richard Feymann was still alive and taught me physics
+ray lin That must be on the wish list of almost all sixty symbols viewers. I know it's on mine too.
+trefod I agree. I enjoy listening to him.
I love how Brody keeps asking the right questions thus leading into a more interesting video
I love this guy, please do more with him!
The fluency and clearness in they way he talks is perfect.It makes those who don't have a physics background help get a grasps on these fundamental ideas. As can be said about all the other talkers on sixtysymbols, and Brady's other channels. Bravo.
Hes such a great communicator
I want this guy as my prof, I could listen to him for hours, his voice is so soothing lol
+xToTaLBoReDoMx it is possible, if you join Caltech as a student.
❤
Who the hell scrambles an egg with the shell still in
DarkLordGiggles Some working physicists, who think too much:)
haven't you heard? it's more organic!!!
australians
HowtoBasic
@Dark People that believe they can unscramble it.
Brady, I love what you have done for us here with all these channels. I don't think I've ever learned as much as when you interview these brilliant people. And your way of asking questions just shows what a great view of life you have and how you really burn for these types of questions.
These channels are my go-to place whenever I need a thoughtnugget, thank you so much for doing this for us!
There's loads coming out this week across my channels!
Never stop
I like this guy. He explains things very well and is enjoyable to listen to. Please include him in more videos.
The arrow of time sounds like something you'd find in a treasure chest in a Zelda game
I love the explanation. Also I love the equations on the board in the background. Details like that can make one feel a lot better, and contribute to a video's quality.
Liked for teaching me the word "retrodicting."
Yesterday, Sixty Symbols taught me "countervailing"
Brady, you do a really great job editing these videos. Enjoyable to watch.
"goes up and and down".. funny face realizing that his hand went in the other order.. "I should say down and up" LOL
Please tell Sean that he needs to narrate a documentary at some point in his life. He is so good at explaining things and I could easily listen to his voice all day!
great to hear - thx
Sixty Symbols Nice video
What makes these videos damn awesome is the fact that Brady always asks the questions the rest of us are thinking about. That's why I love these videos and think that these are more educational than many straight up explanation or teaching videos of the same topics.
I left a glass of water on my bedside table last night and when i woke up there was ice cubes in it. Forgot to say I went to sleep outside at the south pole...
How did it break into cubes though? =O
How did that happen?!
I could listen to Mr. Carroll talk for hours. His mannerisms, speech patterns and inflections make him very interesting to listen to, while his explanations are well articulated for folks who haven't a clue what he's on about going in. He makes complex subjects easy to listen too, and hopefully learn a little from.
He reminds me of James Woods. Wish I had a physics professor like him at university...
Thomace22 he really does.
Stunning line of arguments.
mentions breaking an egg and scrambling it
dumps whole egg in a bowl and tries to beat it
I really love this guy. To me he has a incredibly good interpretation of "things".
Time flies like an arrow. Fruit flies like banana.
I remember reading that in Omni magazine .. "roses are red violets are blue, space is warped and so are you"
Like the frogs say "Times fun when your having flies"
nice copy and paste..
what an incredibly enriching chat! this channel is a goldmine for the mind, this should also find itself featured on the front page of youtube alongside of all the banal content.
Entropy is not what it was.
Chaos is a granularity error.
The definition has become 'messier'
It just complicates matters.
Literally.
Really enjoy the videos you've made with this guy Brady. He explains things very clearly and in a lot of depth and his analogies are so insightful.
8:13 interviewer- time rules your life.. the guy- no one rules my life..(say one more word and imma punch you in the face!!)
Great video, a very clear way to explain the systems we have to use. Although as one of my 1st year students pointed out to me before. The pendulum does slow down.
Time flies like an arrows, fruit flies like a banana . :D
By the way, thanks for being probably the most insightful and broad-ranging youtuber there is :) Keep up the awesome stuff, you inspire alot of people to take up particle physics, mathematics, etc. through your videos.
Does that mean the time on the other "side" of the big bang has an arrow of time going away from us? :D
What do you mean with "the other side of the Big Bang"?
Duh, dimensional theories, it's like an anti-bigbang supposedly going back-timed (for that universe it's forward-- or something I DONT KNOW)
It means that your brain is attempting to move backwards in time by organizing information, while the universe is moving forwards in time by disorganizing that which began in an organized state. We are trying to remember what the universe has forgot.
Really nice question!. However, as time is basically interaction, if nothing occurs before the big bang then there is no change in space. If there is no change in space, then as spacetime is inextricably linked, there will be no change in time, and thus no direction to it.
There are some interesting discussions about that topic
I gotta look that up in that case! In the few videos he has been in on sixty symbols he's starting to become one of my favorite "stars". The way he explains things is extremely clear and always spot on. Enough detail to keep it relevant and correct, but simplified enough so us normal people can understand it in one go.
Quite honestly I'm baffled after every video with him in it. Such a smart and inspiring man to listen to.
The Jack Bauer of Science.
"our universe started in a state of exquisite order" solid quote right there
I thought he was talking about One Direction
As about 12 people have mentioned before me, Sean's voice is great.
The topic/discussion was great too, but there are lots of those on this channel. Sean's voice stands out notably.
Has he ever thought that maybe it could be a big ball of wibbly wobbly timey wimey stuff?
+1 for Hitchhiker's reference. Douglas Adams was awesome.
Andrew Tofelt
Was that in Hitchhikers? It does sound like Adams.
That expression has been used a lot on Doctor Who. I think the first mention was with the introduction of the Weeping Angels.
time in our universe is one dimensional, so unfortunately that reference is false
He's got a good voice and style for this kind of thing. Very clear and engaging.
Time seems to be as physical as it does metaphysical..
Except it isn't. You can measure time, it can be defined by other physical quantities, and you can measure its effects on objects. It is antithetical to metaphysics.
Stop with your nonsense word plays, there are no measurements within metaphysics, there is with time; there's a huge distinction between the two. So yes, I suggest you stop repeating idiocy without conscious consideration of what you're saying.
This guy is excellent with... everything relating to what this channel tries to achieve.
Excuse me, but I remember what happens tomorrow p.o
I uh... eat cereal.
And do stuff... Yes.
No problem. The point to take home is that, other than our own memories, entropy defines events that have occurred earlier with events that have occurred later. If you look at two different photos of the same event, the one with higher entropy can safely be assumed to have taken place later in time, such as a glass of water occurring later than a glass of ice, a slower pendulum occurring later than a faster pendulum, etc.
I don't believe in an 'arrow of time'. I believe that time is just like space, it has no natural direction in which it progresses. The arrow of time I think is an illusion created by the fact that we remember our past and not our future. This gives us the illusion that we are progressing in time and essentially moving from our birth to our death at a fixed rate. This rate would be the speed at which our brains process information and turn the information into short-term memories. I believe that all our versions are existing and real, just as real as a third spacial dimension is compared to the second. Only those versions have different memories which makes each version think it is progressing in time. This is a really interesting way of looking at the difference between the world the way perceive it and the world the way it actually is, with 4 dimensions rather than 3 dimension of space and 1 progressive time dimension.
There is still the question: what is it about that fourth dimention that make any given version of us remember things only in one direction and not the other?
+Ariel Rile Well, quite. The comment seems to be saying "I believe the arrow of time is an illusion caused by the fact that the past and the future are different". It's a bit like saying you believe gravity is an illusion caused by the curvature of spacetime.
So basically, quackery?
I'm another 3+1 dissenter who believes time isn't unique amongst the dimensions. I'm not with you on the many-worlds interpretation, but I'll help you make your case for 4 dimensional space...
Let's start without a reference frame. It is impossible to say how fast objectX is going, the rate of its clock, how compressed it is in any of the spatial dimensions, or its mass. But, objectX has itself as a reference frame. We can now say objectX has no movement in space, its clock runs at full speed, it's uncompressed in all dimensions, and has mass of X. Pick any other reference frame, and things start to change... The subset of possible reference frames that see objectX as moving arbitrarily close to c is still infinite in number.
The universal constant is a ratio of space to time, but thinking of it as a speed gets the numbers right, but misses the point. It's a ratio of equivalence.
One second=186000 miles
Covalence Dust radioactive decay is and example of single time direction. They never gain neutrons. The basic cycle from H to the heavier elements shows the natural world we exist in is omnidirectional.
In the video "Relativity Paradox" on this account, simultaneous events can occur at different times. If the trainspotter was on the end closest to the entrance then the train would first see the guillotine come down, and then see them press the button after the train was through.
By changing your momentum you can alter time in the area around you as well, until you stop accelerating and move at a constant speed.
This channel is regularly blowing my mind. Thinking of time as a similar function of gravity just turned my views upside down.
just realized this is the guy that does some of the best pieces of work for the great courses. if you have audible its a must buy
"Retrodicting"! A wonderful word that I hadn't come across before. Thanks for that.
Check the Sixty Symbols website!
Great video!
The most awesome is the idea of comparing time and space - "space has `arrows` when near a big body" and "time has `arrows` when near a big event"
Another related question I have been wondering about: a lot of scientist say that the universe is infinite in the spacial dimensions, while the dimension of time is finite (big bang till what ever ends it). So why can those three dimensions be infinite while time is limited? Or is that just the illusion created by macroscopic entropy, and we just can't observe beyond the low entropic origin?
I really dig Dr. Carroll! I could listen to him talk about physics for hours (and have thanks to a number of talks available on UA-cam!). Make sure Brady you corner him every chance you can get!
And keep up the excellent work. I would like to see more 60 symbols videos (as much as I like Numberphile I love me some physics...)
Could photon energy form the process we see and feel as the flow of ‘time’ a process of continuous energy exchange or continuous creation?
With light being a wave over a period of time and a particle as time unfolds with each photon electron coupling. The electron is the most spherical object in the universe so this can form the low entropy for the increase in entropy that we have in the Second Law of Thermodynamics.
I love Sean Carroll and I love Sixty Symbols! How did I miss this one.
Some similar thing bugs me about time. R. Feynman has described, for example, that positrons can be thought of as electrons moving backwards in time. Some interactions in the diagrams show parts moving backwards in time. So do physicists actually still think that some particles move backwards in time? Is that a physical reality? Or just a convenient way of thinking about it?
Could the Fibonacci sequence be formed by the spontaneous absorption and emission of light?
All the info I can find says that this process is formed by the quantum wave particle function Ψ of quantum mechanics. When this is reformulated as a linear vector ǀΨ (t) > the two previous vectors are added together to form a new vector this forms the Fibonacci sequence 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ∞
We will feel this process as the arrow of time within each reference frame.
Excellent video! I would like to see more of this professor!
Now an interesting question: how come you're moving down that river if there's no time? You need at least one variable to be constantly changing for there to be motion at all rather than stuff just being there, but if time is fixed then that variable is fixed as well.
Yes there might be, see "heat death of the universe", for example, on wikipedia. But as the article says, there's lots of speculation going on. I just got curious about entropy in the big crunch hypothesis, where the universe ends in a black hole. Black holes have massive entropy (because they the decrease entropy in their environment), but how could it possibly start a "new big bang", where low entropy is needed?
Could time is an emergent property with an Arrow of Time for each individual reference frame with the future continuously coming into existence photon by photon? The quantum wave particle function Ψ or probability function of quantum mechanics represents the inward absorption and outward emission of light with each new photon electron coupling representing a new moment in time within that ref-frame. Photon energy forms the process we see and feel as the flow of ‘time’
Congratulation to Brady and Dr. Sean Carroll for the great video! It was such a good conversation! Thank you very much
Time can move in any direction. It's not a question of "which way it's going," but rather where the system is going, what direction force is being applied, where heat is being released, so on. He did say what direction it's going in - toward entropy. And I believe it was an analogy, the astronaut - and a 'relatively' good one.
I've heard an explanation for the arrow of time that goes something like this: You can only observe increasing entropy because increasing entropy is the only way to disseminate energy that can be observed. It may be that time goes in both directions simultaneously, but we are unable to observe the reverse evolution of the universe. If you were to reverse the scrambling egg, you'd have to reverse the molecules that formed the memory of the egg ever being scrambled in the first place.
I like the way he talks - very clear and concise.
Can you do a video on how the thermodynamic arrow of time relates to the psychological/documentary arrow of time; i.e. we can remember events to the low entropy direction of us, but not events to the high entropy direction of us, and we feel that what we do now can effect events in the high entropy direction but not the low entropy direction?
He's a great speaker. Who knew you could take such a wibbly-wobbly concept of the arrow of time and make it sound so logical?
Could someone please explain the word "entropy" in an easy way?
I've just looked it up but I still don't get it...
I have no more filmed, but if I get to see him again I'll bring my camera!
I enjoy his voice and how he formulates what he says.
I've heard this explained before, but not quite as well. Thanks Brady and Sean!
A proton travelling backwards in time would still have a positive charge, it's +1 charge comes from the sum of charges of the two up quarks and a down quark that make up the proton, the fact that it's travelling backwards through time doesn't necessarily convert the quarks to anti-quarks. Just my guess, but you might want to check that up, it's a good question :D
I quite enjoy these videos with Dr. Carroll, do you have plans for any others?
Professor - look into the discussion of time in St. Augustine's Confessions books ten and eleven. I don't remember whether he considers the arrow of time but he has some surprisingly modern-sounding ideas about time and human memory - back in the 400s AD.
There is something I never understood about thermodynamical arrow of time - there is slight probability that some unordered system of, say, gas molecules at some point creates low entropy system, like all particles being in one corner. 2nd law says that, somewhere else, entropy increased so that total entropy increased. But how can we be sure?
@sixtysymbols, I think you guys should have an online physics/mathy competition for those aspiring physicists(myself included) to win a trip to view Nottingham and meet the professors! or just a prize or something, but that would be really cool.
in addition to or instead of the entropy factor, I wonder if the many worlds interpretation of QM is a quality of the directionality of time. if universes split into multiverses as time goes forwards and as entropy increases, do separate universes re-merge into one if entropy decreased with time?
Starting at the level of an atom with its electron cloud surrounded by vast other clouds of uncertainty but each with probabilty and when acted upon a definite arrow has been created and entropy is in action. I am curious to know how the probability clouds allow time to propagate and the variances in possibility outcomes .
The Law of Conservation of Energy puts a lot of rational consideration toward the initial, low-entropy levels of our early Universe. Before inception, no energy was being transferred - you could call the 'time' before that event a Universal Ground State. There were no systems in place to attain to the Second Law of thermodynamics yet, yielding no entropy. It increased as systems were introduced.
Brady, you're right about a lot of the questions you ask. Many of our assertions hinge on semantics.
Thing that puzzle me…
If the arrow of time begun at lowest entropy (Big Bang), why Universe preferred current direction of time dimension versus distribute on both directions from point of one lowest entropy towards two directions to highest entropy.
With analogy of space-dimension astronaut, he is pulled to Earth same as some other astronaut on opposite side of Earth. Space-dimensions doesn't prefer one direction over other.
I'm not sure but given the statistical definition of entropy is
Maximum entropy=Log ( Number of micro states of the equilibrium position )
I'd assume it depends on how much stuff there is in the universe and how big the universe is. So if the amount of stuff in the universe is finite and so is the universe itself, then so will the number of micro states which would be possible would also be finite and so there would be a maximum value resulting in maximum entropy. I think.
So if we started off at the Big Bang with the lowest possible entropy, when the process reverses and we get nearer to the Big Crunch, does that mean entropy will decrease and things will become increasingly predictable??
Very Interesting video, as usual from sixtysymbols, thank you! It did however somewhat strike me as odd to say that Aristoteles didn't give time much thought, when in fact his fourth book has four chapters devoted to time. Sure they were not the last words on the subject, but there were some serious philosophical fundamentals laid there.
Was Sean Carroll on the BBC documentary about Feynman that was on the other week? As i was watching it i recognised his face and voice but couldn't put my finger on it...
I was expecting it to be something like that. But isn't it possible for particles to collide/change their momentum without emitting any radiation (or for example entering orbit around one other because of magnetic,gravitational or some other force)? Or does any interaction between any two particles by some law of physics requires that the new state is always lower than its previous one forcing entropy in any interaction there is?
I really liked this episode.
This is the kind of thing I like to learn or hear about.
I just find it so interesting that even the most involved theorists and philosophers etc in the end choose to live their lives as we've always done. It's the greatness of everyday life :)
Continue to: Time is an abstract that represent movement in space.
Each movement of an object* is a reaction to interaction with a force, and each interaction of an object change one or more property of that object, we can look at entropy as an experience point on an object.
* An Object can be the collection of objects or the single object.
That said, a collection of objects can hold varied level of entropy.
Would have liked a link to the full video of the preparation of the Nottinghamshire crunchy omlette.
I recently read his book "From Eternity to Here". It's really, really interesting, and if you have any sort of questions about this stuff it's the one book you need to read.
There are some situations such as air conditioning that would seem to decrease entropy (by making heat flow toward a higher energy region), but when you also consider all the energy expended to power that system you'll find that it more than negates the decrease in entropy. In answer to your question, we call it a "law" because there are no known exceptions, if you find one please tell me :D
Ok. I have one problem with the equations being reversible meaning that time is also. Let's say two particles travel on a collision path with each other and after collision they join up and fly in a direction that's the sum of the two directions. If time was reversible what would cause those two particles to split? There would be needed some event that would make them split, without such event we just have reaction without any action.
Love this guy's voice. I could just listen to him talk physics all day.
he is talking about an ideal pendulum, which would swing forever with no air resistance or friction at the pivot. which can be used as a useful analogy for particles confined to small spaces.
I got obsessed with time when as a 5 year old during a persistent unpleasant experience I realised that time would pass and when it passed it would be as if that unpleasant experience only existed in an infinitesimal moment that had was now gone.
This is of course more about my experience of time, not necessarily its nature.
So many Brady Haran videos released in one day. Today is a good day! :-)
I understand time as happening of events. Processes are going on and we can see some changes and hence we can consider it as a flow of time. But do any events happen with atom? Electrons are circulating around the nucleus but how Sean has pointed, such simple system can't be determined as moving forward in time or backward. So does it mean that every single atom doesn't influenced by time and namely, time doesn't happen for it. And does it mean time happens only for complex systems?
That spontaneous splitting is quite interesting. I'd put my money on instabilities within the particle energy waveform that accumulated over time, and I guess this would also be a good reason why two particles would split when going the opposite direction.
Objectively, I don't think Professor Sean Carroll is any better (,or worse than the others of the professors, although all are GREAT,) than the other professors here at sixtysymbols, but I feel that somehow, his slightly deeper voice and casual way of talking conveys a greater meaning of facts. Again, I'm not questioning the skill, nor knowledge, of other professors, but... aww man, I just enjoy hearing him talk.
Unless you have a factual objection, please don't correct me. Have a nice day. :)
his voice is very pleasing, it is easy listening to him