4 ms·

If there are experiments that can be tried to challenge my own current perspective on the matter, I’m interested. Because to my mind, anything that is said to

If there are experiments that can be tried to challenge my own current perspective on the matter, I’m interested. Because to my mind, anything that is said to emerge implies that the dimension we usually refer to as time is already an implicit hypothesis of this anything being able to emerge. And if there is something out of time, then by its very definition it can’t interact with time: - either there’s a connection with time and then at some point there is a change to that thing that can no longer be considered an absolute static thing as there is a before and after event that this thing is attached to, - or this thing is without any relation to time and thus can not be something that engender time itself. To be clear, I think there is still large room for interpretation anywhere formal mathematical means can give us great insights that would be unreachable without them. Agreeing with equations is not agreeing on the interpretation to give to the equations at a larger epistemological picture, and even less on ontological genesis.

winwang 2y ago
Consider an unchanging singly-linked list as a universe. Time (or perhaps "the passage of time") in the intuitive sense does not exist for this universe, but it does exist in the sense that there is a global ordering of values. But does the ordering of the values come from the edges or the nodes? The ordering requires both. Or, more humanly(?), a film reel. At least, this is how I would think of it if required to give a simple-but-possibly-off-base answer for a possible way time could be emergent (would love it if someone more educated could correct me). This is also known as the Einstein block universe model. Otherwise, since my physics education is far below the actual bar needed to understand quantum gravity stuff, I think back to thermodynamic microstates and macrostates, and how temperature is emergent.
guy234 2y ago
I feel like someone could describe foam emerging from the sea without implying that it is a process in time. It could be thought of as a process relating to the properties of seawater, wave agitation, sand etc. It is possible for a picture, not a video, to depict foam emerging from the sea. Also, there need not be a before or after, or even quantifiable extrinsic changes.
danbruc 2y ago
The bits of a movie on a DVD depict regions of space evolving over time. The DVD and its bits exist in space and time but they are static and the spatial arrangement of the bits is pretty much unrelated to the space depicted by the movie. If you had sufficiently good eyes and mental DVD decoding capabilities, you could look at the DVD and get a God's eye view of the world, see all of space and time at once, at least the parts captured in the movie. Similarly in a computer game, to run into a wall does not require the player and the wall to be next to each other in any real sense, it is sufficient that some code knows which memory locations to inspect to detect a collision and constrain the motion accordingly. Similarly running into a wall in the real world does not require that you are next to the wall in some fundamental sense, the universe could at a very deep level just be a list of object coordinates and the laws of nature would cause a force whenever two coordinates become very close. I will agree with you that it is much harder to think of time in a similar way but I am willing to consider this potentially a limitation of human brains. From Einstein we know about the close relationship between space and time and I can relatively easily make sense of the idea that spatial relationships are not fundamental, so maybe that just carries over to time, even though my brain can not make sense of it.
- TheOtherHobbes 2y ago
  This is one take on what Bohm called the implicate order, and which is implied in non-locality and superdeterminism. Reality is a projection of a hidden system which operates under completely different rules. And when we get down to the quantum level, we start seeing that essential information is somewhere else. You can't look at a single electron and see that it's entangled. So where does the entanglement information live? It's clearly not inside the electron. Is a measurement really an interaction with the projection mechanism? This sounds like simulation theory, but it doesn't have to be. There might be a super-causal system of relationships and meta-objects without needing a "computer" made by a conscious entity to keep track of their relationships.
  - mystified5016 2y ago
    You seem to be talking about the "hidden variables" interpretation. As far as I understand, that theory has been disproven experimentally. The core idea is that entangled particles 'know' their final state when they are created. That information is hidden from observers until measured, but the result is not truly random in the way that QM implies. Experiments have proven that this cannot be true, but I don't understand it well enough to descibe here.
sandgiant 2y ago
There are no such things as absolute static things in relativity theory. "Before" and "After" depend entirely on the observer. Energy/matter and spacetime are deeply connected through the Einstein equations, so much so that they may indeed be "the same underlying thing". Approximate static time and space are convenient illusions/approximations, that happen to be very useful for us as a species when it comes to surviving and replicating, but the Universe has no obligation to cater to our feeble minds or senses when it comes to reality.
- tsimionescu 2y ago
  > "Before" and "After" depend entirely on the observer. This is only true for space-like separated events. But the earth gets wet After the rain started, for any observer in any frame of reference whatsoever. The eggs have to break Before you can make the omelette.
- raattgift 2y ago
  Lorentzian manifolds come with a definition of causality. The spacetime of Special Relativity is a Lorentzian manifold. An additional condition of time-orientability obliterates the free choice of an observer on a "comes-before"/"comes-after" relation between observable events. A further condition of global hyperbolicity also determines the "comes-before"/"comes-after" relation between unobservable events. This condition can be fixed by (i) a non-Minkowski metric, or (ii) by constraints on the pattern of events in the gravitation-free metric of Special Relativity (an example of such constraints is thermodynamics). Sloganizing this: "states of matter tells you what configuration came before/came after" in the second case, and also in the first case if the non-Minkowski metric's source is only matter; otherwise you need to do a causality analysis, e.g. by fixing causal cones on curves (paths, trajectories - they don't have to be geodesics) of interest or solving the relevant wave equations). https://en.wikipedia.org/wiki/Causal_structure https://en.wikipedia.org/wiki/Causal_structure https://en.wikipedia.org/wiki/Causality_conditions https://en.wikipedia.org/wiki/Causality_conditions As a practical matter, the initial value formulation of General Relativity <https://en.wikipedia.org/wiki/Initial_value_formulation_(general_relativity) https://en.wikipedia.org/wiki/Initial_value_formulation_(gen...> (and numerical relativity built on that) is popular and of practical use because so far there is no reason to describe a natural system (where gravity isn't just ignored) in a way that breaks global hyperbolicity.
dist-epoch 2y ago
You can have time without having time - block time https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time) https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time...
raattgift 2y ago
> Because to my mind, anything that is said to emerge implies that the dimension we usually refer to as time is already an implicit hypothesis of this anything being able to emerge To the mind of a physics theorist, emergent means that one theory can be mathematically derived from another theory. Often this is a one-way street where one of two theories being compared is more fundamental in the sense that it cannot be derived from the other, but the other can be derived from it. The other theory is the emergent theory. There are a variety of ways of communicating this idea, none of which are especially satisfactory. For example, the Charlie Wood article in the link at the top says, "Sean Carroll proposes the following working definition: A system is emergent when you describe it with two theories, one of which is more complete than the other." There are a variety of attempts to make this more rigorous in philosophy of science literature - if you're interested in how to nail down "emergent theory" and can't find anything on your own, I'll dig up some references. None of this has anything to do with a definition of time. There are a variety of pairs of time-independent physical theories where one can be derived from the other, satisfying my definition above (and usually Carroll's too). In general it is perfectly reasonable to use different formalisms to describe the same unchanging system, and sometimes one or more of the formalisms can be derived (i.e., can emerge) from another, or at least (using Carroll's definition) one of the descriptions is less general than the others (in the sense that a small change of the system can be captured by the more complete theory, but not by the other less-complete one).
- psychoslave 2y ago
  This is one thing to say that a system can encompasse/handle all the analysis that an other system can represent, and not the over way. It feels like here there is something very different with a claim like "time is better understood as an emergent property and if you disagree your logic is broken" as can be found in this article. Maybe there it's about some isomorphism where time is in a bijective relationship with something else? Your references are welcome, yes
  - raattgift 2y ago
    I don't really understand what you're trying to say. I think there's two things going on in your comment: you want more information about emergent theories, and you want more information about how time emerges in a theory that is symmetrical under time reversal. For the first, perhaps you should try Sabine Hossenfelder's video and video-transcript at <https://backreaction.blogspot.com/2020/04/what-is-emergence-what-means-emergent.html https://backreaction.blogspot.com/2020/04/what-is-emergence-...> first, rather than something more technical. For the second: your paraphrasing, particularly "if you disagree your logic is broken" is in my view unfair to the quoted scientists and the author & editor. However here's a handful of paragraphs on how time can be understood as an emergent property. tl;dr of below: the behaviour of matter in the bulk breaks the time-reversal symmetry of fundamental physical equations and provides a "clock" that solutions of these equations do not. Since a direction of time can't be obtained by these fundamental equations, but can be obtained by non-fundamental bulk behaviour theories (like statistical mechanics, which captures the collective behaviour of many items described by fundamental theories, with that collective behaviour being qualitatively different than individual behaviour) time can be said to be emergent. I'm hoping that your "logic is broken" paraphrase is just that you don't understand that any monotonic function on a path through spacetime can serve as a clock, and while there is no a priori correct path, there is always at least one extreme path through spacetime from which one can take a global notion of time. For example, in the FLRW universe, the comoving coordinate time is suitable. However, this time is not the wristwatch time of an observer who sometimes accelerates to a significant fraction of c, and sometimes decelerates to a tiny fraction of c, and the function transforming the two times (comoving time and this particular proper time) is complicated. Connes & Rovelli in the early 1990s originated the idea of using Boltzmann entropy as a "universal" clock comparable to comoving time: in both cases the behaviour of bulk matter allows for a set of coordinates that most observers can relate to their proper time. Entropy is more general since it's not restricted to an expanding and at large scales isotropic and homogeneous universe; it just requires thermodynamic matter. The details are in papers which are probably too technical for most -- a copy of their 1994 paper in Classical and Quantum Gravity can be found at <https://arxiv.org/abs/gr-qc/9406019 https://arxiv.org/abs/gr-qc/9406019>. One could summarize: galaxy clusters spread apart with high-quality vacuum growing in between them; in galaxy clusters, "metal-poor" gas clouds collapse into stars, chemical enrichment occurs through stellar evolution, successor clouds collapse into stars with more "metal", and so on; black holes form, merge, and grow. All of this can be time-oriented such that the future having more entropy. There are other "decays" of matter that can serve to break microscopic time-reversal symmetry which have been proposed and even to some extent demonstrated. Practically all of them rely on a sizable collection of in-principle reversible microscopic changes that in practice -- and in large numbers -- will not reverse. Consequently you can examine such a clock and tell if it is ticking forwards or backwards. Again, that's what's meant by time as an emergent property.
layer8 2y ago
Emergence has nothing to so with time. Emergence means that a lower-level description logically entails a certain higher-level description in some nontrivial way. Both exist at the same time, there is no chronological sequence. It’s a process of logical implication, not a process in time.
- psychoslave 2y ago
  Look up some definitions for emergence: https://en.wiktionary.org/wiki/emergence https://en.wiktionary.org/wiki/emergence "The act of" is literally the first words of the first definition. There nothing that evokes better the idea of time than an act(ion), doesn’t it? >Emergence means that a lower-level description logically entails a certain higher-level description in some nontrivial way. The description doesn’t occurs out of time, it’s conceptualization doesn’t happen out of time, the proposal that something could happen out of time is happening within time. >Both exist at the same time, there is no chronological sequence. Just because one abstract away chronological sequences doesn’t mean that time doesn’t actually exist as a fundamental dimension. >It’s a process of logical implication, not a process in time. That’s not what documenting on history of logic taught me. I warmly recommend everyone to document on the topic. It’s amazing how different the logical firm fundamental beliefs can diverge over time (and even space actually).

winwang 2y ago

Consider an unchanging singly-linked list as a universe. Time (or perhaps "the passage of time") in the intuitive sense does not exist for this universe, but it does exist in the sense that there is a global ordering of values. But does the ordering of the values come from the edges or the nodes? The ordering requires both. Or, more humanly(?), a film reel. At least, this is how I would think of it if required to give a simple-but-possibly-off-base answer for a possible way time could be emergent (would love it if someone more educated could correct me). This is also known as the Einstein block universe model. Otherwise, since my physics education is far below the actual bar needed to understand quantum gravity stuff, I think back to thermodynamic microstates and macrostates, and how temperature is emergent.

guy234 2y ago

I feel like someone could describe foam emerging from the sea without implying that it is a process in time. It could be thought of as a process relating to the properties of seawater, wave agitation, sand etc. It is possible for a picture, not a video, to depict foam emerging from the sea. Also, there need not be a before or after, or even quantifiable extrinsic changes.

danbruc 2y ago

The bits of a movie on a DVD depict regions of space evolving over time. The DVD and its bits exist in space and time but they are static and the spatial arrangement of the bits is pretty much unrelated to the space depicted by the movie. If you had sufficiently good eyes and mental DVD decoding capabilities, you could look at the DVD and get a God's eye view of the world, see all of space and time at once, at least the parts captured in the movie. Similarly in a computer game, to run into a wall does not require the player and the wall to be next to each other in any real sense, it is sufficient that some code knows which memory locations to inspect to detect a collision and constrain the motion accordingly. Similarly running into a wall in the real world does not require that you are next to the wall in some fundamental sense, the universe could at a very deep level just be a list of object coordinates and the laws of nature would cause a force whenever two coordinates become very close. I will agree with you that it is much harder to think of time in a similar way but I am willing to consider this potentially a limitation of human brains. From Einstein we know about the close relationship between space and time and I can relatively easily make sense of the idea that spatial relationships are not fundamental, so maybe that just carries over to time, even though my brain can not make sense of it.

TheOtherHobbes 2y ago
This is one take on what Bohm called the implicate order, and which is implied in non-locality and superdeterminism. Reality is a projection of a hidden system which operates under completely different rules. And when we get down to the quantum level, we start seeing that essential information is somewhere else. You can't look at a single electron and see that it's entangled. So where does the entanglement information live? It's clearly not inside the electron. Is a measurement really an interaction with the projection mechanism? This sounds like simulation theory, but it doesn't have to be. There might be a super-causal system of relationships and meta-objects without needing a "computer" made by a conscious entity to keep track of their relationships.
- mystified5016 2y ago
  You seem to be talking about the "hidden variables" interpretation. As far as I understand, that theory has been disproven experimentally. The core idea is that entangled particles 'know' their final state when they are created. That information is hidden from observers until measured, but the result is not truly random in the way that QM implies. Experiments have proven that this cannot be true, but I don't understand it well enough to descibe here.

sandgiant 2y ago

There are no such things as absolute static things in relativity theory. "Before" and "After" depend entirely on the observer. Energy/matter and spacetime are deeply connected through the Einstein equations, so much so that they may indeed be "the same underlying thing". Approximate static time and space are convenient illusions/approximations, that happen to be very useful for us as a species when it comes to surviving and replicating, but the Universe has no obligation to cater to our feeble minds or senses when it comes to reality.

tsimionescu 2y ago
> "Before" and "After" depend entirely on the observer. This is only true for space-like separated events. But the earth gets wet After the rain started, for any observer in any frame of reference whatsoever. The eggs have to break Before you can make the omelette.
raattgift 2y ago
Lorentzian manifolds come with a definition of causality. The spacetime of Special Relativity is a Lorentzian manifold. An additional condition of time-orientability obliterates the free choice of an observer on a "comes-before"/"comes-after" relation between observable events. A further condition of global hyperbolicity also determines the "comes-before"/"comes-after" relation between unobservable events. This condition can be fixed by (i) a non-Minkowski metric, or (ii) by constraints on the pattern of events in the gravitation-free metric of Special Relativity (an example of such constraints is thermodynamics). Sloganizing this: "states of matter tells you what configuration came before/came after" in the second case, and also in the first case if the non-Minkowski metric's source is only matter; otherwise you need to do a causality analysis, e.g. by fixing causal cones on curves (paths, trajectories - they don't have to be geodesics) of interest or solving the relevant wave equations). https://en.wikipedia.org/wiki/Causal_structure https://en.wikipedia.org/wiki/Causal_structure https://en.wikipedia.org/wiki/Causality_conditions https://en.wikipedia.org/wiki/Causality_conditions As a practical matter, the initial value formulation of General Relativity <https://en.wikipedia.org/wiki/Initial_value_formulation_(general_relativity) https://en.wikipedia.org/wiki/Initial_value_formulation_(gen...> (and numerical relativity built on that) is popular and of practical use because so far there is no reason to describe a natural system (where gravity isn't just ignored) in a way that breaks global hyperbolicity.

dist-epoch 2y ago

You can have time without having time - block time https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time) https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time...

raattgift 2y ago

> Because to my mind, anything that is said to emerge implies that the dimension we usually refer to as time is already an implicit hypothesis of this anything being able to emerge To the mind of a physics theorist, emergent means that one theory can be mathematically derived from another theory. Often this is a one-way street where one of two theories being compared is more fundamental in the sense that it cannot be derived from the other, but the other can be derived from it. The other theory is the emergent theory. There are a variety of ways of communicating this idea, none of which are especially satisfactory. For example, the Charlie Wood article in the link at the top says, "Sean Carroll proposes the following working definition: A system is emergent when you describe it with two theories, one of which is more complete than the other." There are a variety of attempts to make this more rigorous in philosophy of science literature - if you're interested in how to nail down "emergent theory" and can't find anything on your own, I'll dig up some references. None of this has anything to do with a definition of time. There are a variety of pairs of time-independent physical theories where one can be derived from the other, satisfying my definition above (and usually Carroll's too). In general it is perfectly reasonable to use different formalisms to describe the same unchanging system, and sometimes one or more of the formalisms can be derived (i.e., can emerge) from another, or at least (using Carroll's definition) one of the descriptions is less general than the others (in the sense that a small change of the system can be captured by the more complete theory, but not by the other less-complete one).

psychoslave 2y ago
This is one thing to say that a system can encompasse/handle all the analysis that an other system can represent, and not the over way. It feels like here there is something very different with a claim like "time is better understood as an emergent property and if you disagree your logic is broken" as can be found in this article. Maybe there it's about some isomorphism where time is in a bijective relationship with something else? Your references are welcome, yes
- raattgift 2y ago
  I don't really understand what you're trying to say. I think there's two things going on in your comment: you want more information about emergent theories, and you want more information about how time emerges in a theory that is symmetrical under time reversal. For the first, perhaps you should try Sabine Hossenfelder's video and video-transcript at <https://backreaction.blogspot.com/2020/04/what-is-emergence-what-means-emergent.html https://backreaction.blogspot.com/2020/04/what-is-emergence-...> first, rather than something more technical. For the second: your paraphrasing, particularly "if you disagree your logic is broken" is in my view unfair to the quoted scientists and the author & editor. However here's a handful of paragraphs on how time can be understood as an emergent property. tl;dr of below: the behaviour of matter in the bulk breaks the time-reversal symmetry of fundamental physical equations and provides a "clock" that solutions of these equations do not. Since a direction of time can't be obtained by these fundamental equations, but can be obtained by non-fundamental bulk behaviour theories (like statistical mechanics, which captures the collective behaviour of many items described by fundamental theories, with that collective behaviour being qualitatively different than individual behaviour) time can be said to be emergent. I'm hoping that your "logic is broken" paraphrase is just that you don't understand that any monotonic function on a path through spacetime can serve as a clock, and while there is no a priori correct path, there is always at least one extreme path through spacetime from which one can take a global notion of time. For example, in the FLRW universe, the comoving coordinate time is suitable. However, this time is not the wristwatch time of an observer who sometimes accelerates to a significant fraction of c, and sometimes decelerates to a tiny fraction of c, and the function transforming the two times (comoving time and this particular proper time) is complicated. Connes & Rovelli in the early 1990s originated the idea of using Boltzmann entropy as a "universal" clock comparable to comoving time: in both cases the behaviour of bulk matter allows for a set of coordinates that most observers can relate to their proper time. Entropy is more general since it's not restricted to an expanding and at large scales isotropic and homogeneous universe; it just requires thermodynamic matter. The details are in papers which are probably too technical for most -- a copy of their 1994 paper in Classical and Quantum Gravity can be found at <https://arxiv.org/abs/gr-qc/9406019 https://arxiv.org/abs/gr-qc/9406019>. One could summarize: galaxy clusters spread apart with high-quality vacuum growing in between them; in galaxy clusters, "metal-poor" gas clouds collapse into stars, chemical enrichment occurs through stellar evolution, successor clouds collapse into stars with more "metal", and so on; black holes form, merge, and grow. All of this can be time-oriented such that the future having more entropy. There are other "decays" of matter that can serve to break microscopic time-reversal symmetry which have been proposed and even to some extent demonstrated. Practically all of them rely on a sizable collection of in-principle reversible microscopic changes that in practice -- and in large numbers -- will not reverse. Consequently you can examine such a clock and tell if it is ticking forwards or backwards. Again, that's what's meant by time as an emergent property.

layer8 2y ago

Emergence has nothing to so with time. Emergence means that a lower-level description logically entails a certain higher-level description in some nontrivial way. Both exist at the same time, there is no chronological sequence. It’s a process of logical implication, not a process in time.

psychoslave 2y ago
Look up some definitions for emergence: https://en.wiktionary.org/wiki/emergence https://en.wiktionary.org/wiki/emergence "The act of" is literally the first words of the first definition. There nothing that evokes better the idea of time than an act(ion), doesn’t it? >Emergence means that a lower-level description logically entails a certain higher-level description in some nontrivial way. The description doesn’t occurs out of time, it’s conceptualization doesn’t happen out of time, the proposal that something could happen out of time is happening within time. >Both exist at the same time, there is no chronological sequence. Just because one abstract away chronological sequences doesn’t mean that time doesn’t actually exist as a fundamental dimension. >It’s a process of logical implication, not a process in time. That’s not what documenting on history of logic taught me. I warmly recommend everyone to document on the topic. It’s amazing how different the logical firm fundamental beliefs can diverge over time (and even space actually).