Nobody Knows What TIME Really Is. But it might be this...

this video is sponsored by onedrive stay tuned to the end for a special offer for arvin ash viewers [Music] time is as sure thing in our lives and in the universe as you can get there is no escaping it we've come to accept with no other choice the time will flow forward one moment at a time it can never go backwards we can never revisit our past but why is it this way if you go down to the subatomic level to the realm of quantum mechanics time does not appear to have such an uncompromising direction of flow the equations of quantum mechanics are generally time symmetric they don't seem to have a flow preference you might say they're time agnostic and even at the macroscopic level if you watch a film of a bouncing ball and then you play the film backward it will not be so easy to tell the difference this process also appears to be symmetric in time but as we all know this is not quite 100 correct because at the macroscopic level the ball will encounter friction and heat from the bouncing and it will be losing some energy with every bounce so the ball will not return to quite the same spot as its starting point the ball player will be making up for this by adding energy from his arms to the ball yet in quantum mechanics it's just as natural to go forward in time as going backwards and if we look at a typical finding diagram we can turn the diagram either way they are symmetric with time it doesn't matter so if the world is based on quantum mechanics and quantum mechanics generally doesn't have a direction of time why is time then going forward in our macro world where does this transition from time symmetry at the quantum level to time asymmetry at the macro level occur it begs the question what is time anyway how did it begin and will it always go forward that's coming up right now the nature of time is one of the quintessential mysteries of the universe to understand its irreversibility we have to look for other irreversible processes in nature to see if there's any correlation one such irreversible process is in thermodynamics we're particularly interested in the second law of thermodynamics which concerns the direction of natural processes it establishes the concept of entropy as being restricted to either staying the same or always increasing what is entropy in very simplistic terms it's a measure of disorder thus the higher the entropy of a system the higher the disorder and the second law of thermodynamics tells us that for every process that occurs in the universe the universe will be either more disordered or at least as disordered as it was before there is no process that will result in the universe being more orderly overall now as i said the idea of disorder is a simple way to understand it but a more rigorous definition of entropy has to do with information in more precise terms entropy is related to the amount of information necessary to describe a system let's say we're looking at a neatly cleaned room this requires relatively little information to describe we have a chair here a lamp there a curtain behind the chair etc but now if it's a messy room then it will take more information to describe it like a green shirt draped in a complicated way over the arm blue shirt resting over the arm of the chair and green shirt etc this disorder requires more information to describe in the same way a highly ordered system let's say like two different gases represented by two different colors separated on two sides of a chamber requires much less information to describe than the same number of particles randomly mixed together in a larger volume entropy increases as the system becomes more disordered because it takes more information to describe it thus information is directly tied to entropy and if the entropy of the universe is always increasing it means that the information necessary to describe the universe must also be increasing and this may give us a kind of clue as to why time is going forward how you might ask imagine again that we have two gases on the two sides of a chamber now we open the middle of the chamber to allow the gases to mix they'll mix together to make a kind of purple gas this process only goes one way from an ordered state of two separate red and blue gases to a disordered state of a purple gas a mixture of both gases the key point is that this process is not time symmetric this process is only one way it evolves from one state to the other and you cannot go back to the prior state does this now remind you of the forward-only progress of time the fact that you can never go backwards in time now it's important to point out that it's not impossible for the mixture of gases to go back to the prior ordered state but the problem is that there are so many possible places for the particles to be in the box that the probability of all the red particles to be in one part of the box and all the blue gas particles to be in the other part of the box is effectively zero it is a statistical impossibility it's not as if the reverse process doesn't exist it's just suppressed it doesn't happen so now the question is does increasing entropy cause the forward flow of time time and entropy seem to be related but how do we know one is the cause of the other couldn't it be equally possible that time is the cause of the one-way direction of entropy instead of the other way around entropy says that you can scramble an egg but you can't unscramble it the disordered state of the egg cannot go back to its original ordered state sure this makes sense but if you could reverse time that is if you saw a video of a scrambled egg backward you would see it going back to its original ordered state so what causes what does entropy cause time or does time cause entropy if increasing entropy was directly responsible for the forward flow of time it would be logical to presume that decreasing entropy would cause the backward flow of time there are processes of decreasing entropy everywhere for example the inside of your refrigerator decreases entropy by removing heat that is cooling the inside but time does not run backwards inside your refrigerator it still runs forward if you don't believe me place a watch inside and see what happens note that the second law is still not violated here because the overall entropy still increases when you consider the whole system of the refrigerator and the room that it's in your refrigerator doesn't work unless it's plugged in it uses energy to run a compressor that provides the cooling this creates more heat outside the refrigerator than the heat removed from inside entropy overall still increases to understand its link to time i think we need a better understanding of what time is the problem is we don't really know what it is except that it happens to exist and processes appear to evolve from the past to the future what's the definition of time the best answer in physics is that time is the process that brings the unknown future into a recorded past via the present if you think about it this requires an increase in information because every second every moment that goes by is recorded as a definite past which are events that have definitely happened this was not knowledge until it happened when it happened it became new information and thus added to the total information in the universe more information is more entropy and this could be related to the flow of time according to some theories physicist lee smullin suggests in a 2021 paper that what distinguishes the past from the present is a kind of knowledge that is gained once indeterminate quantum events consisting of only probabilities in the present become a classical definite past according to smallin the past is completely classical they are no longer probabilities they are definite they have already happened they cannot unhappen however the future is quantum it consists of probabilities it is still unfolding so what seems to separate the past from the present is whether it is knowable or not whether it has become actual knowledge something for which we can say yeah it was like this so according to the paper the change from a quantum indefinite present to a classical definite past is what defines the arrow of time this points always in the forward direction as the quantum present constantly turns out a classical past the future is also quantum according to smaller it consists of only possibilities so we are living constantly in the very moment when probabilities become actualized and reality becomes imprinted in the past as actual knowledge although smolin does not talk specifically about information in his paper if one interprets actualized knowledge as a kind of information being added to the universe then perhaps this is the length that connects entropy to time if smolen is correct and the arrow of time is due to indeterminate quantum events becoming the classical past and if this knowledge is leading to more information constantly being created then entropy is also increasing because of its link to information and since the classical definite past becomes known and cannot go back to being unknown time cannot be reversed and entropy also cannot be decreased they all go one way quantum becomes classical information increases entropy increases and time flows only forward note that although it is established that information is related to entropy both smolin's paper and my extrapolation of his paper to information are not established theories but conjecture so you should take this only as food for thought we don't really know what time is but we're quite sure that entropy is increasing in the universe and thus it's getting increasingly disordered this means that entropy must have been much lower earlier in time especially near the big bang how did the universe get to this low entropy super orderly state at the beginning this is a mystery but it brings our discussion of time to the scale of the universe and cosmic time will time continue to flow forward forever to understand this let's consider that entropy is also more precisely the conversion of usable energy to useless energy gasoline or petrol has more useful energy than the byproducts of burning it which is the heat and the gases in the exhaust of your car this type of process is happening everywhere your body is burning sugar and turning it into less useful heat energy for example the light bulb in your home is converting useful electricity to less useful light and heat these processes are going one way and this also leads to the concept of heat death of the universe if the entropy only increases one hypothesis is that one day the universe will be in a state with no free or useful energy at this point the universe will be just full of radiation and heat that can't be used to do any work if this is the case then nothing can happen no physical movement no chemistry not even thoughts in brains so ironically the heat death of the universe is also called the big freeze nothing can move anymore if nothing happens in the entire universe and not even thoughts or consciousness can exist does time still continue to move forward i'm not so sure what we really need is a new theory of time that can be tested and verified to be correct my dream is that someone watching this video right now comes up with such a theory and changes the world if you want to explore the physics of time and detail one of the best courses i've come across is on one dream today's sponsor called mysteries of modern physics time is taught by one of my favorite science educators award-winning professor sean carroll this course takes you on a mind-bending journey to explain how something you take for granted every moment of your life connects you to the very first instant of time at the big bang how the past present and future could be equally real and how you actually live 80 milliseconds in the past you can not only enjoy these great lectures by professor carroll but also some of the best educators in the world you'll be hard-pressed to find a better online learning service than wondria i myself have been a member for a long time i can't recommend them enough you'll even see my testimonial at the bottom of onedrive's home page it's really easy to sign up right now because they're offering a free trial and you can cancel at any time so you have nothing to lose but a lot to gain if you want to support this channel and greatly increase the depth of your knowledge be sure to click the special link in the description and if you have any questions or comments from me or other viewers please leave them in the comment section below i try to look at all of them i'll see you in the next video my friend [Music] you

Channel: Arvin Ash

Views: 1,092,384

Keywords: what is time, entropy explained, what is entropy, time, entropy, lee smolin time, what is time and space, will time end, why was the big bang low entropy, time and information, entropy is not disorder, what is entropy in physics, why does time flow in only one direction, what is time quantum physics, quantum physics, quantum entropy, what is entropy in quantum mechanics, will time reverse, entropy and information, entropy statistical physics, heat death of the universe

Id: mxb336no2rI

Length: 14min 9sec (849 seconds)

Published: Sat Nov 06 2021