8 ms·
Time is an illusion, and these physicists say they know how it works [video]
- cut3 2y agoTime is fun to think about. It seems that the smallest unit of time measures the smallest unit of detectable change in a phenomenon. If awareness is needed for time that hints to me that awareness and time are the same thing, dependently arisen like two sides of a coin. Space is also needed for time as a phenomenon exists in some form of space for it to be observed to change, so it seem that space = time = awareness.
- Xen9 2y agoIn my philosophy, times would merely be various signal clocks. Time in this sense, then, will be the instantenous unit that relates one's environment-embedded consciousness' clockrate to the clockrate of the clock. Consequently, one can have at every moment multiple, changing times. One builds foundations of embedded agency partly on this, signal theoretic, interpretation—without confusing it with the physics notation which has uses elsewhere.
- datavirtue 2y agoIf the universe has only a single particle, is time even possible? I think a universe with one particle is the same as one with none. As soon as you have two particles they can move toward each other, and spin can be observed.
- akira2501 2y ago> If the universe has only a single particle, is time even possible? space is constantly expanding. particles have energy. energy decays. eventually into photos. colors shift red due to increasing wavelength and decreasing energy.
- datavirtue 2y agoWe don't know if space is expanding. The models and observations appear to support expansion. This was just a thought experiment with a theoretical single partical in a universe of unknown size to demonstrate that the universe changes in non-obvious ways as you add energy/matter.
- dingaling 2y agoI'd say yes to time with one particle, as its position within the universe, or the universe's size in relation to the particle, can change.
- ndsipa_pomu 2y agoIf a universe only contains a single particle, then there can be no "position" within the universe as how could you possibly measure it? Similarly, how would you be able to determine if it was static or moving without comparing it to something else?
- slightwinder 2y agoWouldn't a single particle still change, move, experience time? There is just no way to measure time.
- datavirtue 2y agoThere is no way to tell if it is moving.
- fatata123 2y ago[dead]
- slightwinder 2y agoYes, but that is irrelevant. Change happens, even if you can't recognize it. Recognizing change is a shortterm-problem. But longterm it can be relevant, if the particle some day will break down, disappear, burn out, or whatever happens to them.
- excalibur 2y agoI think that's gonna depend heavily on your definition of particle. It seems most likely that our current universe is a singularity, a single point that contains the entirety of space and time, such as they are. Viewed through a certain lens this could be considered a particle, but I'm not sure that it checks all the boxes for properties you associate with one.
- magicalhippo 2y agoYou would need memory as well. Without memory you wouldn't be able to detect change over time, and hence not the existence of time. And without that you can't have awareness (as I understand the word).
- mitthrowaway2 2y agoIndeed. And the direction of memory is one of the things that determines the arrow of time, perhaps the most important one.
- BLKNSLVR 2y agoIf I remembered tomorrow yesterday, then today exists to make it true.
- leptons 2y agoMeasurement, awareness, and memory, are not required for time to exist. These are all things that make observation possible, but time could still exist even if the universe were just a fog of loose atoms bouncing around with no self awareness.
- magicalhippo 2y agoOf course. I was just trying to point out time is a necessary but not sufficient condition for awareness.
- mr_toad 2y agoThe past light cone of an object constrains what past events can affect an object regardless of whether the object has awareness of not. So you don’t need memory to experience time, even if you need memory to understand it.
- thunderbong 2y agoThat's a very interesting point. I had never considered it. I have always conflated the perception of change with change itself. What you wrote was quite profound to me! Thanks.
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- majoe 2y agoI think you won't gain anything from conflating "detectable change" and "awareness". We kind of already had this discussion in Quantum mechanics with "observations" and the "consciousness" of an observer. Nowadays the information theoretic point of view is prevalent among physicists and an observation is often seen as just a correlation between the observer system and the measured quantum system. No consciousness needed. Nevertheless I agree, that it is interesting to think about time as an series of changes or events instead of just as a dimension of 4D spacetime. I didn't watch the video yet (I prefer text), though, so I refrain from bothering you with may opinion on this topic.
- dr_dshiv 2y agoRight, we could instead say “sensation” as in “sensor.” Nevertheless, I like that “time” and “experience” are often synonymous—eg, “I had a good time.”
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- akira2501 2y agoIf you're on a space ship travelling at 0.86c, your Lorentz factor is 2, and so time is moving half as fast for you. Yet if you measure the speed of light it will be the same. Then if you look out the window you will see the universe is 1/2 the size it used to be in the direction you are travelling.
- drdeca 2y agoI don’t see why space should be required for a change to occur. Now, particle spin may be associated with a physical direction, but I don’t see why it needs to be. Why not say “we have a unit vector in C^n evolving unitarily” (Where C^n is n-tuples of complex number) ?
- InDubioProRubio 2y agoIf you take the quantum field of view.. its the start of interaction between two particle-permutations forcing a breakdown into a observable and measurable interaction? Time is the expansion of the involved while simultaneously collapsing complexity permanently.
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- marcus_holmes 2y agoneeds [video] tag on the title - this is page containing a link to a YouTube video. I would have ignored it if I had known.
- ta2234234242 2y agoOriginal video: https://www.youtube.com/watch?v=uYOF-YggWAg https://www.youtube.com/watch?v=uYOF-YggWAg
- ninth_ant 2y agoBoth the video and the linked blog are by the same person, so for what it's worth it's not some low-effort business insider blogspam.
- acheron 2y agoLunchtime doubly so
- state_less 2y agoSometime in your life you will have occasion to say, ‘What is this thing called time?’ - Nina Simone https://youtu.be/OXeh742_jak?si=Rwe4ev44rrjTL_Az https://youtu.be/OXeh742_jak?si=Rwe4ev44rrjTL_Az
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- dang 2y agoUrl changed from http://backreaction.blogspot.com/2024/08/time-is-illusion-and-these-physicists.html http://backreaction.blogspot.com/2024/08/time-is-illusion-an..., which points to this.
- readthenotes1 2y agoI have a relative who holds the view that time is illusory, especially when hen is under the effect of some toxin. I ask hen: when did you figure this out? The answer inevitably starts with a story that happened many years ago and I point out that if time were illusory then there is no appropriate way to answer the question. Because hen is drunk or stoned, I get to do this multiple times. It's not the time is illusory, it's that hen doesn't remember.
- ImHereToVote 2y agoYou are related to a drunk chicken?
- whamlastxmas 2y agoFor others that don’t know, it’s a gender neutral pronoun but seemingly mostly in Swedish
- NotGMan 2y agoAn interesting way to think of time is that it's really a measure of change of position. Even atomic clocks measure time by the change of position of particles. We measure years by the positional change of the Earth relative to the sun. Each human made clock measures time by some positional change which repeats in equal enough intervals to stay consistent.
- _factor 2y agoTime = Distance / Velocity A simple middle school formula really spells it out clearly. If you’ve no distance or velocity, you don’t have time. If we pretend that velocity is heat (electron excitation, though technically a cloud), you can see why we can never get to absolute zero without discontinuity (black hole), so time increases or the universe gets larger. There is a reason being cold, slow, and dense are linked. You can keep increasing the heat to “infinity”, making time slower and slower relatively.
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- poikroequ 2y agoI had a similar line of thinking. Just because you can measure something doesn't mean it fundamentally exists. We can measure things like pressure and temperature, but that doesn't mean they are fundamental in any way.
- programjames 2y agoSomething I've heard physicists say but doesn't make sense to me is, "gravity is a just a distortion in space-time, it's not like the other forces." Can someone with more knowledge than me explain this? As far as I can tell: 1) General relativity is just a model. 2) The force that was observed as gravity can be modeled as a a distortion in space-time. 3) Thus (circular logic incoming), gravity is not actually a force, it's just a distortion in space-time, and that why it looks like a force. This is just begging the question. I could say the exact same thing about any of the other forces between particles, just instead of using the permanent[0], I'd use the determinant[1] for fermions or the immanant[2] for anyons. I remember in my electrodynamics class applying relativity to Coulomb's law, and seeing the magnetic force just pop out in the Taylor expansion (and I just learned the Feynman lectures does this too: II_13-6[3]). So what do physicists mean when they say gravity is special, or general relativity doesn't play well with quantum dynamics? [0]: https://en.wikipedia.org/wiki/Permanent_(mathematics) https://en.wikipedia.org/wiki/Permanent_(mathematics) [1]: https://en.wikipedia.org/wiki/Determinant https://en.wikipedia.org/wiki/Determinant [2]: https://en.wikipedia.org/wiki/Immanant https://en.wikipedia.org/wiki/Immanant [3]: https://www.feynmanlectures.caltech.edu/II_13.html https://www.feynmanlectures.caltech.edu/II_13.html
- freetonik 2y agoI’m not a physicist, but I think the comparison is made between gravity and e.g. strong nuclear force. In the latter, the “force” is modelled by interactions between hadrons, with virtual particles (distortions in various fields) mediating the interaction. With gravity, there are no particles (though graviton is a hypothesis). One can say that space time is also “field”, and mass creates distortions, so gravity is just like other forces interacting via field distortions, but iiuc, unlike nuclear forces, gravity does not have a quantized mathematical model.
- untoxicness 2y agoThe best understanding of matter is in the form of quantum field theory (QFT). QFT is always formulated with some background metric (geometry) of spacetime as an input. One idea is that the metric (geometry, gravity) could be a field just as matter is a field and people tried to apply the standard rules of (perturbative) QFT to gravity but failed. This is because the theory of gravity is unrenormalizable [0]. An interesting avenue in saving this line of thought is asymptotic safety where the idea is that gravity coupled to the standard model could actually be renormalizable in a certain sense [1]. In any case general relativity and quantum theory have so far been irreconcilable and there is now consensus on how to bridge the gap between those two theories. It is exactly because of this that most physicists will think of gravity and the other forces to be of a different nature. When people say that gravity is not a force they mean that there is no known particle which acts as the intermediary of said force. For all the other forces we have a theory that explains the exertion of force via a particle. Your first point states that "general relativity is just a model". Many physicists believe that it is more than a model but a true description of what the world really is like. I understand your urge to label theories as models, but ultimately the question is whether or not there is some level of ground truth that can be accessed in the form of mathematical theories. [0] https://en.wikipedia.org/wiki/Renormalization#Renormalizability https://en.wikipedia.org/wiki/Renormalization#Renormalizabil... [1] https://en.wikipedia.org/wiki/Asymptotic_safety_in_quantum_gravity https://en.wikipedia.org/wiki/Asymptotic_safety_in_quantum_g...
- madmaniak 2y agoTime doesn't exist. This is a human concept to measure mutations. Brain preserves previous states - it is a feature of a brain. It doesn't require time - it just preserves previous states like a history pattern. What exist is constant change - here and now. There's no time.
- freetonik 2y agoThis doesn’t help because you can say the same about space.
- mz00 2y agoCan you really? IMO, time is immutable and irreversible. Space is permanent and shared.
- freetonik 2y agoWhat do you mean time is irreversible? Your movement in it is irreversible, just like your movement on a one-way road is irreversible in space. Time itself does not possess the property of irreversibility, at least in modern physics. All the equations describing natural phenomena can work both ways, forwards and backwards in time.
- madmaniak 2y agoThis is what differs model from reality. You're talking about abstract concept which helps you to measure mutations but as I tried to explain above - is not a real thing. It's just working and useful idea.
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- ackbar03 2y ago“Time is a flat circle. Everything we've ever done or will do, we're gonna do over and over and over and over again … for- ever.”
- Guthur 2y agoThis sounds very similar to how Henri Bergson describes time in Time and Free Will. Particularly chapter 2 the Multiplicity of Psychic States. And as he says the fault is making extensity out of duration and therefore producing nothing more than the ghost of space. I can't possibly do it justice here, highly recommended read for the curious of thought.
- codeulike 2y agoYou shouldn't take 'Illusion' too strongly here. Ms Hossenfelder is saying that conceptually time can't really be separated from 'change' so the only way to measure time is to have some constantly changing but steady ticker like a pendulum. This has always been a problem in quantum mechanics because you can't study the a system independently of its clock, you have to add the clock to the system. The video is discussing a paper where they use entanglement and a tiny ticker to get around this problem. Arxiv: https://arxiv.org/abs/2310.13386 https://arxiv.org/abs/2310.13386 So don't worry everyone time still exists.
- hnthrowaway0315 2y agoDarn I wish I could go back in time.
- vehemenz 2y agoNo need to invoke metaphysics here. Whether time is an illusion or not doesn't depend on its "existence," though I'm not sure what you mean by "exists." I'm not convinced anyone does. I agree with your overall point though. All we really need to say, when we say something is an "illusion," is that the phenomenon in question is not as it intuitively appears. Our expectations were one thing, but because of x, y, and z, this can't be the case. We think of it one way, but it's actually another way. It's tempting to draw this distinction upon metaphysical lines, e.g., we thought it was one way, but here's how it Really (TM) is. Again, this is totally unnecessary and adds nothing to our scientific understanding.
- Lichtso 2y ago- Classical mechanics: Basically views time as another spacial axis. In classical mechanics bodies can be viewed as being a 4D extrusion of their 3D shape along a 1D time path. High precision simulation of classical mechanics does not model time as steps / frames in a movie, but as a continuous 4D geometry. - Relativity: Builds on classical mechanics idea that time is a geometric axis and using a 4D coordinate system. What is further added is the possible distortion of that 4D spacetime. - Quantum mechanics: Strictly speaking quantum mechanics does not model time at all. It is more like algebra. It only describes equivalences / transformations which can occur. When we reformulate some algebraic expressions we don't think of the steps we take as time steps. It wouldn't work anyway because there are many possible paths not one. It is not a 1D sequence but a graph, which can even contain cycles. - Thermodynamics: None of the other areas of physics make time "pass", because to them time is symmetric and past and future might as well be swapped. Only thermodynamics introduces an asymmetry by coupling it to information theory: On the macroscopic average, entropy can not decrease, only increase. Thus, we get a global gradient form low to high entropy, which is what makes time irreversible on a large scale.
- creata 2y ago> High precision simulation of classical mechanics does not model time as steps / frames in a movie, but as a continuous 4D geometry. What is this sentence referring to, if you don't mind me asking? I know that some implementations of collision detection use volumes swept over time, but that's the only link I'm aware of.
- Lichtso 2y agoYes exactly, continuous collision detection (CCD) is what I am referring to. https://scholar.google.com/scholar?q=continuous+collision+detection https://scholar.google.com/scholar?q=continuous+collision+de...
- plaidfuji 2y agoCongratulations, you’ve just explained relativity, QM and thermo more clearly and concisely than years and years of other courses and literature. Thank you.
- paulnpace 2y agoWithin her discussion is the unscientific "humans have no free will" statement. Free will is experienced as a part of the consciousness, which we cannot point to, physiologically. (For those who point to the head region as "containing consciousness", this is also unscientific.) The most annoying part of the video is that her statement comes off as this being simple observable fact that "everybody knows" and is a good example of why articles on topics are best when kept on topic. My own observation is that time is better described as human narrative description of events in the observable universe. I have not read the paper referenced in the video and I have to really spend time on these things to recall the concepts such papers are typically breezing through, but when I have attempted in previous years to understand how scientists explain time, they seem to usually have little agreement and lots of guesses. I have not found scientists claiming they have discovered fundamental units of time. I have not found scientists claiming they can sample time. I have not found scientists claiming they can isolate time. I have not found scientists claiming to have derived time as some sort of force in the universe. I am not clear on how something that has no fundamental units, cannot be sampled, cannot be isolated, and is not a force can also be something in the physically existent universe. Yet, scientists seem to place time in their explanations and equations as something that de facto exists.
- the_other 2y agoI still don't get it. Everything which occurs involves change. Change implies time and motion and exchange only happen over time. Without time there is no big bang, no "work", no decay, no expansion, no energy propagation, no chemical reactions, no state changes... probably no resistance. How can "the speed of light is the speed limit of the universe" and "time is an illusion" coexist?
- Balgair 2y agohttps://en.wikipedia.org/wiki/Timeline_of_the_far_future https://en.wikipedia.org/wiki/Timeline_of_the_far_future This article is one of my favorites on Wikipedia. The last bits are maybe the best for this question. Somewhere in the very far future, time will lose all meaning. In that, the universe will be so big and so empty that if you ran time backwards it would not look meaningfully different than it running forwards. All matter that is left will have devolved to the basic particles and the universe will be in the maximally entropic state. So much so that the page correctly stops labeling time in any unit. It's not that if you could pop into this future and then look at your watch, that it would not tick. All laws of physics still apply, 'time' is passing still. It's that for the rest of the universe, 'time' has become something different. I'm not in the field anymore, but this maximal entropy and time's use are obviously linked. A nanosecond or a gigayear are both essentially noise in the time spans that these events occur in. Time, very truly, is meaningless to our future dead universe.
- xtiansimon 2y ago“Brain into mush”, “post pics on instagram”. I really like the topic of no-time in theory, but I would prefer more philosophy and less culture jargon.
- keester 2y agoShe mentions free will as an illusion. To me this is a purely philosophical question and I prefer Daniel Dennett's take on it. He's saying it has nothing to do with determinism or indeterminism in physics and has a very good explanation. https://www.youtube.com/watch?v=5cbxi7ZZIoU https://www.youtube.com/watch?v=5cbxi7ZZIoU
- newusertoday 2y agoyou can easily find it yourself? check yourself it you have it or not.
- mensetmanusman 2y agoSpace is also an illusion, but for who?
- troyvit 2y agoI'll believe it when I all the sudden remember that they said it in 2018.