Might I just say, you, Sir, are our generations Feynman. Different character, but approaching the same hair style (like it) and keeping us normies amazed with physics. Thank you!
Time is not real. Its just an artificial human invention. Hume said enough perhaps when he called it a "convenient description". A clock artificially divides something but I am not sure if it is known what it is that it is being divided. One can say the earth turning on its axis in 24 hours is what is being divided. But that simply defines Time by an arbitrary marker, the revolution of a planet. The Universe has no time reference.
Im from africa & i wish we had things like this growing up. I basically just watch physics topics on youtube & i wouldve loved to actually study it but physics just wasnt in our imagination. I did really well in science at school & it was my favourite subject but when it came time to go to college we were basically told go into engineering or law. I received a schoalrship for engineering degree, but looking back its actually very strange because i achieved top 3 for science in the school. If youre a young person watching these videos youre lucky & should go chase your dreams because its all there for you, just go for it & do it.
Tiaan , you and your brain capacity will eventually derive a finer more acurate theory about your own story but you eont emerge on a higher level unless you allow things to be the way they are.
Hey, Sean, thanks for a nice lecture! About 15 minutes in, I start losing some frames of your head, while the blackboard is smooth, not sure if it's my problem or yours, or YT's decreased quality policy. I watch other videos without a glitch. Stay safe and keep them coming!
I so enjoy this stuff from professor Sean Carroll. Everything so nice explained, easy to listen. Listen it to every night. Thank you! Greetings from Serbia! :)
Wow how lucky we are to get to watch your video. I just love how you plug your book, I will definitely be ordering. I would be very grateful if you could give your view on Roger Penrose CCC theory, I really find this concept exciting, look forward to your value view point.
Can the Universe remember itself? I've listened to Leonard Susskind's fractal time interpretation, and that seems to be robbing us from any insights into the past. Also, how far can a gravitational wave propagate? Does it have some sort of a Hubble radius before it dissipates?
gravitational waves do not dissipate. They continue to lose strength as they spread out, forever. In GR, the wave can diminish forever as a continuous value. In quantum mechanics, you eventually reach the quantum level of a graviton, but that is so small that it will be way past any ability to detect the gravitational wave using any kind of physical process.
An additional point about there not being free will is that "now" in your brain is a construction. If you clap your hands, the sound and the image seem synchronized, but hearing is a much faster sense than sight. Your brain does a ton of processing to recognize faces, create stereoscopic vision with distances, etc. Yet your brain syncs it up after the fact. I also remember a study where an fMRI showed that the brain sends signals to move muscles before the decision part of your brain "decides" to move those muscles. Conscienceness feels just like the brain creating a story to tell itself to make sense of what it just did and of whats happening on the other side of your skull.
I like time travel stories in which event A causes event B, which then causes event C, and then C re-enforces B to happen and creates a loop. In this sense, A is no longer needed to sustain the loop, and may as well have never happened, but explains where the loop came from. This loop could then be considered a "whatever happens, happens" situation, where no matter what you do, you will always re-enforce the loop.
PUN 1: I'm no boxer man. I prefer German shepherds. PUN 2: I'm no boxer. I'm a karateka. Which one is fundamental and which is emergent? Which one is passive and which is active? Are they both paradoxes or none? _you have 42 units of time to answer or not_
Time is a compact dimension one single Planck second in size. This is why we are always in the present and can't move in time. Time is a hyperplane of present. We exist on one side and antimatter on other. Here is topology.... Sin(cos(u/2)cos(v/2),cos(u/2)sin(v/2),sin(u)/2) 0
12:40 My intuition about presentism is that reality might feel to be only the present moment as a result of how our brains/ perceptions work... we perceive only a part of the whole, for whatever reason (perhaps evolutionary?)
I like to think of free will as the chaotic bit in a bifurcation diagram. Constant inputs but the output is chaotic. The same way you can have a faucet with a constant valve opening and water pressure yet the rate at which the drips come out is random. Likewise your brain can be made up of deterministic bits however the output can be random. Then overlaying our consciousness on top of that feels like free will. Sure I "chose" to pick this box over the other, but that was just the randomness speaking.
Sean: if a person (or energy) is sent into the future or past that energy must be accountable. Which version of "time" pays for you being there or spent energy displacement. Unless the universe "borrows" said energy and either repays later or gets a credit. Unless time doesn't exist, so who cares when you get what it's owed. And if you disagree, then you'll just have to accept the fact destiny exists. Lol. Sean literally just stole what I was thinking as I typed out. 😂
"Whatever happens, happens" only works if there is a "pre-existing" loop. Not being able to change macroscopic historical events is a red herring, since the presence of your future self in the past at all would violate WHH if it hadn't happened already. So the history you remember before traveling back in time must include your time traveling self having been part of it, whether the pre-travel you knows about it or not.
In a sense it sounds like you are saying that traveling back in time would also make you become younger and also in those places you were at each stage
Dear Doc; Time and entanglement are mutually exclusive as superposition precludes acceleration and the time function. That's why we need a dual membrane electromagnetic field with an antimatter half that doesn't have a time function and this brane produces entanglement through strings that are paired with matter strings to form 1 to 3 aspect ratio tori that we call gravitons. The circuit or conduction tesor formed keeps these strings from annihilating as does the conduction tensor holding graviton clusters together, (looks like a barbell). Time just renders these antimatter strings to a recessive manifestation in the graviton and subsequently more complex structures incorporating gravitons. Gravity is just the electromagnetic processes applied to the flow of graviton and graviton clusters around and through Standard Model particles. The clusters are actually gluons that were formed en mass during the GUT Epoch and are continually formed in SM particle cores. These gluons/clusters act like a dipole gas subject to condensation via Feshbach resonance and BCS field effect, and this condensate is formed in the electromagnetic field of galaxies as dark matter that is scattered by cosmic rays . The dipole gas is spin and charge coupled on the surface of leptons and baryons to form the Higgs field operating as an electromagnetic rectenna generating space-time viscosity as it captures the momentum of gravitons and clusters flying through the field. The gas is also the working fluid for a gravitational propulsion system operating as an “ion thruster” through the core of the leptons and baryons. Dark energy is just the increase in quantum friction of the propulsion system in barren space where the Higgs field drags the particle backwards toward even less dense space.
Walter Williams and His Flying Time Travelling Ring - A True Story (Parallel Realities with Overlapping Timelines) The O'Jays - Live At Daryl's House 2016 Uploaded to RU-vid by Funkyscope July 7, 2016 34:40 Sitting around the dinner table with Daryl Hall, Walter Williams of the O'Jays recounts a time years previously when his ring went flying off his hand while he was performing at a concert. After the show someone knocks on his dressing room door to return his ring. Walter says the person is from Pottstown, (Pennsylvania) which turns out to be the hometown of Daryl Hall who is sitting at the table as Walter is retelling the story in 2016. Daryl Hall comments 'That's where I'm from. That is why you got the ring back!' This is one example of a moment I've been able to document over the past few years. Many people have had similar experiences. Bumping into someone unexpectedly, thinking of someone and seeing them or hearing from them soon after, etc. The question is, are these glimpses of parallel realities with overlapping timelines that create the 'coincidence', is it an Einstein Rosen Bridge, or does it just represent a sophisticated series of schedules and data and events that synchronize only 'once in a lifetime' that you couldn't repeat or 'make happen' if you tried, that indicate something else, a technology or intelligence, such as AI, is able to 'schedule a coincidence'. The megaplatforms that deliver data through algorithms have much of the data that such a system could or does use 'behind the scenes', it appears, 'scheduling the future' by recording today's events and then by simulation or algorithm, the schedules occur on into the future, more or less. Phenomenal and hard to comprehend though it may be. The story of Walter Williams' ring is both hilarious and phenomenal at the same time. I don't know who Funkyscope is that uploaded the video but it appeared through the RU-vid algorithm in my feed before your upload here the other day. It is very apropos. After the O'Jays at Daryl's House video, the RU-vid algorithm on autoplay goes on to play Huey Lewis and The News 'the Power of Love' while in my Google newsfeed is a picture of the movie Back To The Future with the Delorean. 4 days before I saw a Delorean in real life while taking a 'spontaneous' walk around the block. I have noticed and documented thousands of examples of similar coincidences, whether they are images, words, or movies or music I have seen or seen recently appear in varying order through algorithms on platforms run by AI in the days, weeks and months ahead of time, sometimes synchronizing 'in real time', a bit more than what one would call deja vu, and more like a rubik's cube of data that goes around randomly until something matches and appears in the feed, and then it goes around and around again until something else matches up, and so on. I think the rubik's analogy is the closest explanation but I'm wondering if you have any other ideas about how kismet can actually be scheduled or even programmed regarding future events if enough data is available to do so. It can be both exhilarating and eerie at the same time because it does lead to the question of whether free will truly exists when you see it happen if you contemplate all of the variables that had to line up to for the coincidence to occur. Also, observations like this would not be possible without the platform delivering information, even though the information appears organized without regard to time, or ownership rights, yet it creates or somehow commingles and then shows a coincidence. Daily. Anyway, I have had such coincidences occur many many times, though much of it is a mystery as to how or when it will happen next, with most coincidences occurring 'automatically' by the platform matching the data in the background on it's own and delivering it by algorithm, or just by my interacting with the data it delivers matching data and images subsequently as it has in other examples I mentioned. I've also heard this called 'the frequency illusion' where something recently seen or heard is seen or heard soon afterwards or you start noticing something 'everywhere', a color, a word, etc., or patterns reoccurring with greater frequency. The manipulation of human memory also occurs by the altering of how images are presented giving rise to false memory phenomenon, even when you present the argument that there is no way to go back and alter a previous timeline in order to make the false memory true. It is a false memory today as there is no corresponding previous timeline where the misremembered events could have occured. False memory induction is a high risk when data is presented without regard to time which can have a powerful influence on the perception of time and how we remember the events of our lives. Thanks for great shows! I've been able to understand these phenomenon because of what I've learned from your lectures, particularly regarding black holes.
For the "whatever happened, happened" stuff, I think a better way of looking at it is that the past becomes your personal future as a time traveler, so you have factual information about your own future. The question is, if you know baby Hitler is not going to be killed by you, do you give up trying? If you give up trying, is THAT why baby Hitler never died?
For some reason, in my head, I imagine Block universe as a block of cheese. you cut a hole through the block, if you slice that block up you will still have a hole in each slice
Sean i hope you are aware that, you mess my head up.. in a good way :). Now im cursed being in my head, with having that 100 yard stare, tomorrow at work while i try to figure this shit out.
Great fun, thanks for doing these videos. I have a question about free will with respect to time reversibility. Maybe there's no point to thinking about them together, but the thought popped into my head, so... It seems like the notion of free will isn't reversible. Say you went to a shooting range and fired ten shots. Running that backwards wouldn't mean you were "willing" bullets back into the gun, which is a weird enough thought. But maybe it would mean you had the will and ability to somehow "catch" speeding bullets into the barrel of a gun every single time, which is it course impossible even if you had the will to do it. In reality, with your brain also working backwards, no such thought could occur in the first place, so the concept of free will is simply not reversible. Is there even a point to thinking about this scenario? Thanks again and looking forward to more videos!
If you were looking at the thought processes of the brain running in reverse, it might seem that way. There was a sci-fi story written from this point of view.
Free will is associated with complexity. As extremely complex beings, a perturbation as small as a decision can vastly affect our distant future. Even more delicately, the events we remember and the options we envision greatly affect the decision we make. The big bang and all of the local light cone history since made that decision mine to choose, but I reject the premise that the big bang was so perfectly balanced in every way that my choice was only an illusion. I reject the premise that we are not responsible for our actions. At the very least, ignoring and rewarding bad behavior encourages everyone else to indulge in bad behavior. Those who have studied history know this to be true. Indulging our instincts increases entropy more rapidly than conscientiously paying attention and acting occasionally to restore order as we pass.
A compatibilist might say "free will exists" in the same way that "a table or chair is 'solid'"; the fact that nothing is truly "solid" doesn't change how we use tables and chairs. The rub here, imo, is that the operational belief that chairs are solid is not something people use to validate the pursuit of retributive justice, nor does it substantiate medieval metaphysical intuitions of an immortal soul and the threat of damnation in the afterlife. If free will is as real as tables and chairs then it becomes almost impossible to make an objective argument against "eye-for-an-eye", capital punishment, vengeance, not to mention all the needless anxiety people carry everyday for "what could have been".
Accordingly to the Wheeler-DeWitt equation, the universe is timeless for any external observer. Thus, though time is a real emergent phenomenon for internal observers, it is absent for external ones. In this regard, the block universe picture (with time being one dimension) is misleading as it gives an impression of time as something that exists independently from an observer.
So I realized why Newcomb's Paradox is a paradox. Its because even though the predictor already knows the future, it still gives us 2 possibilities. Having 2 possibilities is incompatible with the block model of universe, there should only be 1 possibility. The predictor should just say 'this is what you are gonna do' and the universe will somehow conspire to make it happen. The paradox is ill-posed.
I believe time is same for everything and it’s not relative. When we say gravity or speed slows down the time.. it is really not slowing down time but it’s slowing down the atomic/molecular activities of every particle. It’s the slowness of activities of particles creates the effect of time slowing down. Time flows the same regardless where you are in the universe or how much gravity or high speed the thing is traveling at. It’s just at different gravity or speed... the molecular activities slow down or speed up for every single particles in that situation. Hope I can somehow express it better what I mean.
Fun comment, as economist, it depends on your propension to risk to decide which box you choose. Without additional information, like the probability of each outcome, I'd chose $1000 cash, because the other box doesn't exist for me (even with one quadrillion dollar inside). I'm wired that way, I was born like that. And that is not actual free will!
Does time travel affect the hallowed conservation of {mass, charge, etc}? Moving matter through time via time travel would seem to require conservation to be across the entire block of time, but that counts things more than once, which seems fishy.
I like to think of machines that can tell if something changed been exist or not exist but not which one. It could have changed from exist to not exist or it could have changed from not exist to exist. Then, create information out of those machines. In other words, imagine our experience as one step removed from full reduction. Always have one remaining process that's unsolved. Hofstadter's "Godel, Escher, Bach" grapples with a Zeno recursion version of this kind of thought experiment. Prime numbers do not allow space for it.
Block u niverse doesn't imply static time. There is a computer game Achron that has an ontology that is a growing block dynamic universe. As a person deep enough into time to write a book about it you might be interested in that and talk to doctor Hazard about it. One of the frases used to refer to the staticness property is game of thrones with "the ink is already dry". If we live in a universe where we visit a page only once it doesn't matter a whole lot whether the ink is dry or wet as the page will read something when we visit it. If you can revisit pages and the ink is dry then it is possible to concive of THE CANONICAL HISTORY of the universe. The dynamical option is somewhat theorethically messy. And a lot of thinkers are only comfortable assuming some kind of staticness. One good formulation is Novikovs self-consistency princple (becomingness can't change the probability of any events). However there doesn't seem to be good reasons to rule out or against the dynamical option. In a dynamical block universe a demon might have to do more computation. The dynamical view also has the issue/feature that the change can't be in respect to time (need another time dimension or some addition like that). But if the laws of physics are primarily consistent in this "wetness" sense then they are also approximately consistent in clock progression sense. In principle some facts could depend on which "revision" of the history books is in effect but if there is local connection between cause and effect there is a (potentially very long) uninterrupted story that spans all the revisions.
In Newcomb's Paradox, could you choose box A and disprove the predictor (because if B has 100000, you could have choose both and he would have been wrong or if the box B has 0, you could have choose just B and he would have been wrong) ?
Thank you so much Sean for answering my question about time travel to the past. The Newcomb's paradox is very thought provoking too. Can't wait to see the next video 🙌🙂
Velocity is a vector. It is distance with direction/time. So reverse velicity can be distance in opposite direction/forward time. Thus, the reversibility of laws of microphysics really means reverse velocity with time still going in forward direction. In other words, reverse flowing time is not necessary for the reversibilty of laws of microphysics to hold. And it makes sense because the notion of reverse flowing time does not even make sense. Tim Maudlin has similar thoughts on this. Appeal to reverse flowing time in the context of reversibility of laws of microphysics is misleading. The correct way to think about the reversibility of laws of microphysics is to say that if we reverse the velocities of all particles, we will still deduce the same laws of physics by observing such a system.
i think at all times in the universe every next one second in the universe everything will have changed even space itself yet time does not change nor promote change.. it simply denotes change the past is the proof
Time travel paradox works only if the consciousness of self is preserved, so if the past is unique about all the particles that makes our body and all of the universe, time traveler's particles could end up in the same past,since it already happened could resume it's history in the present, so time traveler may always reach the present may be
What I liked about this Lost time travel theme, the ''What happened, happened''', this was because the universe was self-correcting. In other words, if you change the past, the universe has laws that will bring the events as they used to be. For instance, you go back in time to make sure that your girlfriend doesnt get in the car in which she died in a car crash. She does get in this particular car and she is saved. Well, she might die two days later, hit by a bus. So, she will die anyway to keep the time-events coherence of the universe, to keep the future events linked to her death synchronized with her death. It is like a tv serie version of the entropy or the least action principles. What happened is what has the highest probabillty to happen. You can come back in time to bring a stupid rock uphill, but it will come down to the bottom as soon as it has an opportunity.
With Newcomb's paradox, if the boxes are already set, aren't you then predicting the past? The answer lies in the observers future, but the quantifiable reality is already determined.
So a compatibilist says yes there is likely no free will, however the illusion of fee will gives a virtual choice in the real human existence and its more useful to accept the choice illusion?
I imagine you've read it yourself, but one of my favorite philosophy reads is "Bananas Enough for Time Travel?" The argument in that paper is that consistency-preserving backwards time travel requires the presence of consistency-preserving coincidences; e.g., just as you are about to pull the trigger on Baby Hitler, you slip on a banana peel. This is eventually spun into an argument that that time travel should be considered metaphysically impossible.
Solution to the conflict of past vs free will: it is in the name. One is only free to do stuff in the future, not the past. Otherwise it would be called free did.😂
So if I understand correctly the only force in the block universe is that time moves forward? And there really is no concept of physical law, it is an illusion?
The time-traveling historian fiction of Connie Willis should be mentioned (try to ignore the first novel's use of telephone tag as a plot device, time travel exists in future Oxford, UK but mobile phones don't). Definitely portrays a one-timeline, or "whatever happens, happens" universe. The mechanism for avoiding paradox is the time travel portals which don't always work reliably. If a traveler would change the past, the portal will not open to that place and time. I won't mention whether the other case ever occurs, portals instead working reliably and travelers contributing to known history. Spoiler for Avenger: Endgame ... but it instead portrays a multi-timeline universe, with its own wrinkle that's portrayed fairly consistently. Their technology works such that after changing the past (though they try not to), traveling forward again takes them *not* to the new future created by those changes, but the unchanged timeline they left from. Lots of other fiction instead freely mix-up their rules to serve the story.
I’m not really sure that I understand the point (or usefulness) of Newcomb’s paradox. I guess my stumbling block is that you say it is already decided that B has $1M or $0, but the Predictor implies that my choice of A/B/A&B changes what’s in B. Which is contradictory
At ~17:00 you say we don’t see the pass, we see light hitting our eye right now, and we infer it came from a past star, etc. Doesn’t this mean your position is that it is not correct ever to say we ‘observe the world’; we in fact are only o observing the sense data streams into us at that moment. Going a step farther (too far?) are you not getting lost in an infinite regress, in that you are talking as if there is a ‘self’ that observes ‘our own sense data… I think my last sentence is going too far - but I’d like your answer to my prior worry. Are you ok with saying all scientific statements about an ‘external world’ are be only inferences from our sense data.
So, is reversibility a true symmetry of nature? Has anyone every formulated a replacement for Newton's second law that only makes sense in the forward directon?
If you consider the entire universe moving backwards, how could you tell? If it then went forward again, you might find yourself in another branch. Again, you wouldn't know. Further, if a version of you goes to another branch, isn't that what happens all the time anyway? What's the difference? That version of you has its own consciousness in any case.
if we could stop moving in space what would happen with time. if you traveled near light speed age slowly so if you stop moving in space would you age quickly
48:00 If the predictor knows the future, it should not give an "if" claim, because it suggests a choice on my end, which is against its ability to predict perfectly.
It seems possible that the fact that baby Hitler wasn't killed doesn't demonstrate either that the past is immutable or that time travel is impossible. It might be that in order to travel to the past, you have to understand the system so clearly, that anyone who has the capability to do it, must also not want to. Like nobody would ever go past the event horizon for the bragging rights.
I need a clarification - Electrons do have a mass then it should experience time. If an electron is left to its means then, after a period of time (well it could be very long), quantum properties should change over time (statistical probabilities) . Right? What am I missing?
I know you probably won't do a Q&A of a Q&A, but I wonder how we would reconcile free will, to whatever extent it exists, with the block universe concept of time.
I asked this question once on a pantheist forum (I was, and am curious) and someone there offered the following "Everything may have already happened, but that includes the choices that we make". I don't buy it at all but I thought it was a clever answer.
The box at any point in time is either empty or has money in it. Unless the rules specifically say that the content can be changed later based on your choice, the predictor can not make a statement like that about the future. It is equivalent to saying that if you choose A I already put the money in the box, if you choose B I did not, as if you were to transfer the information about my future choice into the past. It is just another time travel paradox.
Sean emphasizes that the boxes will not be manipulated. What one sees is what the choice is made from; an observed $1 thousand dollars or an box that may contain $1 million or no money. The predictor is saying that only if you choose Box B alone will you get a $1 million dollars. Any other choice will get you $1000 dollars or nothing
Engaging talk and the use of “real time” gfxs(is unreal time "negative time?!”) via the iPad and green screen tech creates a more accessible, coruscating conversation of a very complex concept.Thanks Sean for taking the "time out" in creating these timely -"CoVid time" -talks.
If information is taken from the future and added to the present then the present information would be increased which contradicts the conservation of information ie QM
@@rufusapplebee1428 I doubt that the universe is a simulation, so "cheatcode" does not apply. In physics, information is the objective measure of a physical event. Encryption deals with the subjective sense of information.
Disclaimer: Not totally familiar with the nuances of No-hide theorem. The first question that comes to mind is, if the whether is predicted, does that add to present information? In fact, isn't what is known about the future being added all the time? Wouldn't information about the past also add to the present's information?
If quantum particles can be both a wave and a particle or waveicles, why can't time be both passive and active? Kind of a background time that maybe infinite, and a local changing/passing time?
Quantum particles are never both wave and particle in the moment you measure the particle. But yes. What about gravity from that electron, that is measured after the double slit, and depending of measurement, the electron did go through both slits, or it did go though only one side slit as a particle, with another path prior to the location where you chosed to measure it as a wave or particle...... ...
Will Time Dilation depends on direction if the one-way speed of light is individuel per direction? Up/Down Time Dilation depending of directional velocity relative to where one is at a xyz-velocity that equals the one-way speed of light, likely as the CMB? And so also defines a lowest possible time dilation relative to all surroundings?
Would a flip picture book be an effective analogy for the question of "block universe unchangingness" The book is the block but each page is different from the one before and after but still a part of a unified whole.
I find many who think that time is "active" (like Lee Smolin) don't really have a convincing argument, other than to say it just "feels" that way intuitively. Obviously I don't know what the answer is, but relying on your own senses to guide you to the ultimate truth is not very scientific.
I wish I had found these videos earlier. I guess I'll ask my question anyway though its probably too late to answer. I think what's getting me hung up about time and a block universe is that I'm saying the word "exist" sometimes and "real" other times as though they mean the same thing. But I'm not sure you wpuld agree that they do. Its had for me to think of a future that already "exists" but I'm not sure that is the same as its "realness" from a physics perspective.... I dunno what I'm saying am I on to anything?
What’s everyone’s opinion on that Bill Gaede guy that has some vids on time as well but disagrees with most physicists on how Time works and time dialation? I mean who is right? Time totally hurts my brain trying to grasp it. It’s insane
What about this idea? Wouldn't that also be taking you back in time? You're locally changing the shape of space to go faster than the speed of light. Search Results Web results Alcubierre drive - Wikipedia en.wikipedia.org › wiki › Alcubierre_drive The Alcubierre drive, Alcubierre warp drive, or Alcubierre metric (referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a ... Warp-field experiments · Miguel Alcubierre · Casimir effect · Exotic matter
I disagree. The color and arrangement/patterns impressed upon one’s retinas is a direct result of events that happened in the past. Just like when I see something in the same room. Where is there a distinction?
