[Source]: Popular Mechanics
Time has puzzled scientists for many decades. Does it meaningfully exist apart from our experience of it as everything moves toward the disintegration of entropy along its irrefutable arrow? You can't put the "spilled milk" of the weirdness of time back in the jug.
Could the observable universe be exclusively composed of layered, mutually entangled systems?
The passage of time puzzles quantum physicists, who seek to fit it into a cohesive model.
One wild theory posits that time visibly passes because we're entangled with ... well ... everything.
In new research published in the American Physical Society's peer-reviewed journal Physical Review A, scientists from Italy (led by Alessandro Coppo) try to translate one theory of time into real life—or, at least, closer to it. The theory is called Page and Wootters mechanism, and Coppo has studied it for years. It's a quantum mechanics idea that dates back to 1983.
Journal Reference:
Tiago Martinelli, Diogo O. Soares-Pinto. Quantifying quantum reference frames in composed systems: Local, global, and mutual asymmetries, Physical Review A (DOI: 10.1103/PhysRevA.99.042124)
(Score: 3, Interesting) by Anonymous Coward on Friday June 21 2024, @10:21AM (9 children)
If I generate a simulation of a universe on a computer, there's not necessarily any past or future of that universe to "jump to", unless some state is stored. If there's no stored state, to go to the past in such a scenario, one would have to reverse everything.
In the PacMan computer game from the perspective of PacMan while there could be time (and speed), there's no past for PacMan to go to.
Of course if there's a God-like entity outside the Universe, they might "relatively" have infinite backups, or they have infinite computing power so to them the past universes still exist. But that doesn't mean it exists for us.
That said, that consciousness thing is weird. AFAIK there's no current known theory or law of physics that would cause/require consciousness to necessarily exist in a pure mathematical simulation of our universe.
Makes me wonder if God found it amusing to make a Universe where idiots and geniuses; fools and the wise; all can't really explain the very first observation they make - consciousness; and arguably the only observation they can be sure is true and not faked.
(Score: 3, Interesting) by acid andy on Friday June 21 2024, @11:00AM (3 children)
Time is almost as weird as consciousness and the two are probably tightly linked. Both time and consciousness have the slippery property of seeming to escape outside of any model we try to make of them. For example with consciousness, we can keep adding levels of detail to a model, with light striking a retina, electrical impulses traveling along nerves and through brain neurons and chemical signals in synapes, but someone can always ask, OK but why am *I* experiencing that information *now*? With time, say we model it with the playing time of a DVD movie, or the play time of the PacMan game. When we do that, we still don't have a concept of a present moment until a conscious agent plays the game or the plays the movie, where playing them means making their state vary over time, and time being the time we all experience in reality.
Welcome to Edgeways. Words should apply in advance as spaces are highly limite—
(Score: 4, Interesting) by JoeMerchant on Friday June 21 2024, @08:09PM (1 child)
If time is an illusion, I'd say it's Trillions of big illusions (one per consciousness), not one.
Perception is all there is. Every consciousness has its own unique perception. We may agree on some core principles, but overall each of us experiences the Universe from our own unique vantage point - our perceptive inputs are more different than alike.
We perceive time, it's how our wetware gets from one time to the next, by seemingly causal relationships with some degree of unpredictability we attribute to free will, but that's surely more a construct of what we call our consciousness than any physical property of the universe. Thermal noise? More likely a failed understanding of the true deterministic properties at play.
Every subatomic particle is entangled with every other in a mesh more vast and complex than we can ever begin to understand. If we did, even on a local to the planet scale, predicting tomorrow's lottery numbers would be a trivial emergent property of such understanding. There are more particles in the Earth's biosphere than there are planets in the visible Universe... the idea that each somehow affects all the others merges random chance with deterministic outcome of such tremendous complexity that we are unlikely to ever describe it completely for more than trivial experimental situations.
IBM and Xanadu Borealis are working around 1000 qbits... meanwhile, in one of your eyes there are 120 million rod cells, each with ~75 million rhodopsin molecules waiting for photons to trigger your perception of light. Rhodopsin is a rather complex protein consisting of O(500) amino acids.... thousands of atoms per molecule. Just to contemplate the complexity of just your photo-perceptive elements in a single eye, there are more protons, neutrons and electrons involved than there are planets in the Milky Way, by many orders of magnitude. Our best quantum computers look like a two bead abacus by comparison.
🌻🌻🌻 [google.com]
(Score: 2) by hendrikboom on Saturday June 22 2024, @01:48AM
Then the multiple-reality interpretation of quantum measurement just posits more unique perceptions.
(Score: 0) by Anonymous Coward on Saturday June 22 2024, @03:28AM
That's why everything doesn't happen in an instant.
[1] Maybe the speed of light is infinite but appears finite because not all infinities are the same... 😉
(Score: 1) by khallow on Friday June 21 2024, @12:21PM (4 children)
A dimension is precisely that. Once you have the premise of dimension in existence, you have the consequences.
(Score: 0) by Anonymous Coward on Saturday June 22 2024, @03:22AM (3 children)
Or does that mean if I dream up stuff, that stuff will actually exist in this universe?
(Score: 1) by khallow on Sunday June 23 2024, @03:09PM (2 children)
When something behaves like a dimension, then the consequences of a dimension follow. That's the real power of math models. It's not that we can force physical reality to follow the model, but rather that we have physical features which strongly enough manifest math objects like the concept of dimension that we can build useful math models from that.
(Score: 0) by Anonymous Coward on Tuesday June 25 2024, @12:38AM (1 child)
(Score: 1) by khallow on Tuesday June 25 2024, @03:18AM
It "doesn't have to be", but it does. It fit the basic requirements of a dimension and hence, the consequences follow.
(Score: 4, Insightful) by Thexalon on Friday June 21 2024, @12:15PM
"Time is an illusion - lunchtime doubly so."
"Think of how stupid the average person is. Then realize half of 'em are stupider than that." - George Carlin
(Score: -1, Offtopic) by ls671 on Friday June 21 2024, @01:26PM
The passage of time puzzles quantum physicists? They should ask Kamala Harris, she seems to know quite a bit about it, at least she talked about it extensively in one of her speech but I didn't listen attentively.
Everything I write is lies, including this sentence.
(Score: 4, Touché) by HiThere on Friday June 21 2024, @01:48PM
The phys.sci link has an abstract that talks about the system evolving where the system includes the clock that measures time. To me this would seem to imply that time was happening anyway, the question being whether it could be measured.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 3, Interesting) by VLM on Friday June 21 2024, @02:28PM (1 child)
This concept that I don't entirely understand seems closely related to the arguments in Wolfram's recent works, which I also don't entirely understand, so I'm not sure how closely they're related, but they're obviously in the same family tree, although probably not very close to each other.
An incredibly bad automobile analogy would be something like a car's moving parts wear out or "age" or "cars have an arrow of time" in how the moving parts relate to each other, which is different than the classical model of car aging based on parts rusting in isolation from the other parts or some mysterious handwaving "you just know". Probably not my most accurate automobile analogy.
Anyway in summary a lot of "this" reads like stuff I've read in recent Wolfram books. He and/or his ghostwriters squirted out a couple books in quick succession recently, metamathematics and something about the thermodynamic second law and I think some other books. The thing about very speculative physics is it's hard to say if it's a couple of decades ahead of its time or if it's just hard sci-fi; ironically, either way you look at it I enjoyed the Wolfram books.
The overall impression I have of Wolfram's ideas is he's over impressed at how a small simple algo can generate wild crazy outputs; there's a smart boy who never used GDB or a similar debugger in anger. Believe me back in the old days you could spend infinity time trying to debug something that only had 256 bytes of RAM and almost worked, because I was there, so its no surprise to any programmer-type that intentionally chaotic code does not need to be overly large or complicated to be chaotic. Or going the EE route he's a smart dude but he never generated chaos waveforms on an oscope using a handful or less of opamps.
(Score: 3, Funny) by hendrikboom on Saturday June 22 2024, @01:46AM
Imagine getting the array bounds wrong in a sorting algorithm and ending up sorting the binary code itself!
(Score: 4, Funny) by srobert on Friday June 21 2024, @03:53PM
People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly wobbly, timey-wimey stuff.
(Score: 2) by The Vocal Minority on Saturday June 22 2024, @03:05AM
OK, so I read the abstract of the paper and then the magazine article and I have no idea how these things are supposed to be linked, or even really what that article is about.
(Score: 2, Interesting) by pTamok on Saturday June 22 2024, @12:18PM (5 children)
We might not live in three spatial dimensions : "The three-dimensional world of ordinary experience––the universe filled with galaxies, stars, planets, houses, boulders, and people––is a hologram, an image of reality coded on a distant two-dimensional surface." [wikipedia.org]
It 'time does not exist', then I'd love a layman-approachable explanation of how to resolve CP-violations [wikipedia.org], as it is CPT that is meant to be invariant [wikipedia.org].
(Score: 3, Touché) by maxwell demon on Sunday June 23 2024, @10:15AM (4 children)
Well, the "time reversion" operation T isn't really running time backwards, but transforming a state into its "time-reversed" state, that is a state whose (forward) time evolution is the reverse of the backward time evolution of the original state. More exactly, take an initial state and let it evolve for a certain time (that is, calculate what the state should be after the time passed, according to the theory). Then do a time reversal operation, which gives you a different state. Then let that state evolve over the same time again. The result is the same as if you just time-reversed the initial state.
For example, in classical mechanics, time reversal basically means reversing all velocities. If, for example, you have a planet orbing a star, and after some time you reverse the velocities, and wait for the same time again, the planet will have returned to the original position, but still with the velocity reversed.
Now the point is that time reversal is actually a transformation of the current state, which by itself has nothing to do with time; for example, time reversal in the Schrödinger equation is simply taking the complex conjugate. There is no reason you cannot take the complex conjugate of a complex function, even if there is no time.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 1) by pTamok on Monday June 24 2024, @03:46PM (3 children)
Well, yes, and no.
Mathematically, you can do anything that is expressible in well-formed statements, but in this case, the mathematics is explicitly meant to be modelling the 'real world'. So while you are perfectly correct that it is 'just' a complex conjugate, the point is that it is interpreted as modelling the 'real-world' experience of time.
Mathematics is not the universe*, but it is a useful 'language' to construct models that describe the universe as we see it, and if we are using a particular formulation to describe 'time', it's not correct to suddenly say, oh, it's just a mathematical operation, it's not 'real'.
I'm certainly open to the suggestion that time is an illusion, in the same way that three-dimensions could be an illusion in the holographic formulation of a model of the universe. It boils down to what models describe the universe as we see it, without errors, and which make testable predictions. String theories make predictions we can't (as yet) test, as the tests require energies and structures larger than we can produce and/or manage, so some people regard them as less 'useful' as a result.
To be fair, the universe is complicated, and there is not 'law' that says that it should be describable by a small set of elegant equations - our experience is that some remarkably simple assumptions allow us to model the universe at large scale quite well, and also at very small scales quite well, but the models are incompatible - and we know that the large scale models are incomplete. It could well be that the universe ends up ultimately being only describable by something as complicated as itself, which would be disappointing.
It is also an interesting philosophical problem: how do we know that time passes? We could just be created with (false) memories of a past and an expectation of a future, and be deleted in the same instant. Why do we thing of one thing following another, with no backwards motion in time seen.
Furthermore, we 'know' time is relative. Einstein gives us different relative motions in time (see the twins 'paradox'), but going backwards requires some 'interestingly' difficult engineering (infinite length cylinders, for example).
It's also possible that humans do not have the intellectual capacity to understand the universe. Perhaps we need to build an AI to understand it for us.
*Some people think it is, but I won't go down that rabbit-hole.
(Score: 0) by Anonymous Coward on Tuesday June 25 2024, @12:49AM (1 child)
It's useful but is it sufficient? Can math generate qualia and consciousness?
As for "knowing" time passes that can be done with memory storage and retrieval. A mere computer can "know" time passes, nothing fancy needed (unless you mean knowing including qualia/consciousness). When the memory is faulty (dementia, drugs, etc) then the perception is different.
Can there be Relativity without Time being a dimension? Just stick to the speed of light etc stuff, but without assuming there's Time.
(Score: 1) by pTamok on Tuesday June 25 2024, @05:48AM
Unless you hew to the school of 'the universe is mathematics', then no. I think it is the 'wrong' question, and should be "Can mathematics model qualia and consciousness?". I would be of the opinion that mathematics probably can, but we don't know how to do that yet.
The question here is "What is 'knowing'?", which comes back to qualia and consciousness. There is currently loud debate on whether current instantiations of 'artificial intelligence' have consciousness or not. My view is currently, no. Then again, does John Searle's 'Chinese room' have consciousness? Be aware that you might have a false memory of time passing.
Presumably, the person who posits that 'time' is 'simply' hyper-entanglement thinks so. One interesting idea is that of the 'static' universe, where time is a dimension and 'world lines' are non-changing paths through the 4-dimensional 'thing'. In this hypothesis, choice is impossible, as world lines don't change in the future as well as in the past.
Time, as we perceive it, is odd, in that the past is immutable, and the labile future is crystallized into the past by the choices we make at the present moment - almost as if 'time' is a phase transition (crystallization) in the space-time continuum - like the moving boundary between solid and liquid in crystal growth being 'the present'.
(Score: 2) by maxwell demon on Tuesday June 25 2024, @07:37PM
Probably I didn't get my point across well. The point is that the state doesn't explicitly contain time. While with P reversal there is an explicit location dependence that you have to reverse, the same is not true for time. There is a location operator, but no time operator. Time is merely a parameter.
This is also already the case in classical mechanics: The locations are part of the state of the system. Time isn't. Mirroring space involves changing the sign of positions. Mirroring time OTOH justreverses velocities.
And yes, in general relativity time can do more interesting things. Which is one reason why people are still struggling to get general relativity and quantum mechanics together. General relativity knows nothing about the CPT theorem, BTW.
The Tao of math: The numbers you can count are not the real numbers.