5 ms·

Right, and that was the point I was trying to make with the human analogy. So the question is whether spacetime is one of those patterns we can point to, like

Right, and that was the point I was trying to make with the human analogy. So the question is whether spacetime is one of those patterns we can point to, like a "human" a "chair" or an "atom", which is what we call "real" in our everyday language, or whether it is only a useful modelization tool, like the Aether. There are no pattern anywhere in the universe matching the Aether. It is a valid question.

AnIdiotOnTheNet 6y ago
I'm saying the differentiation is meaningless. We have a model of space time that makes accurate and measurable predictions and that is as real as real gets.
- Voloskaya 6y ago
  So then the Aether was real for a while and stopped being real 200 years ago? If we discover a new model that makes better prediction than our current spacetime based model, just like relativity was to Newton's theory, will spacetime stop being real? The article was clearly using "real" with the definition we attach to it in our everyday language, not in deep philosphical sense.
  - AnIdiotOnTheNet 6y ago
    > So then the Aether was real for a while and stopped being real 200 years ago? Yeah, pretty much. > If we discover a new model that makes better prediction than our current spacetime based model, just like relativity was to Newton's theory, will spacetime stop being real? In so far as Newtonian gravitation is also not-real. We still use that model for a lot of things of course. I don't know much about Aether theory or its predictions, so instead I'll use another long gone theory for my example: People used to model the motion of "heavenly bodies" using epicycles, complicated circles-within-circles patterns that assumed the Earth was the center of the universe and everything was taking a very complicated path around it. These epicycles were actually quite good at predicting the motion of planets and stars, so as far as anyone was concerned they were real. Some clever people eventually came around to the idea that all of that could be much more easily and more accurately modeled if we put the sun at the center. Of course we know today that that isn't quite right either. We don't, and possibly cannot, ever know if the models we use to describe the world around us are the most accurate or not. They are real when they work, because we have no better metric to determine their reality.
    - Voloskaya 6y ago
      I do agree with your point, but I think we are seeing the limit of language: when we don't attach the exact same definition to words, we can misunderstand each others while trying to convey the same thing. The way you use "real" is the way I would use "valid": A theory is valid until proven otherwise. And the way I use "real" (and I think it is the same way the article used it), is whether something has any grounding in our universe (some pattern as you said before). For example, wormholes are possible following the theory of general relativity, but we don't know if they are "real", e.g. can there actually be a wormhole in our universe. If we do end up finding one, then they are real. If we however find conclusive evidence that they cannot exist in our universe, then they are not real, but only an artifact of our (incomplete) theory of general relativity.
      - AnIdiotOnTheNet 6y ago
        > And the way I use "real" (and I think it is the same way the article used it), is whether something has any grounding in our universe (some pattern as you said before). Many of the things you described as "real" don't have grounding in our universe, i.e. things like "chair". It's possible I misunderstand your usage of the term "grounding". > For example, wormholes are possible following the theory of general relativity, but we don't know if they are "real", e.g. can there actually be a wormhole in our universe. If we do end up finding one, then they are real. If we however find conclusive evidence that they cannot exist in our universe, then they are not real, but only an artifact of our (incomplete) theory of general relativity. Sure, but how does that apply to spacetime? We know, so far as anything can be known, that space and time are two different perspectives of the same thing. Relativity described it, and we have measured and the effects it predicts with startling accuracy. Here's a question: It matters if wormholes can or cannot exist regardless of if the current model permits them or not. Does it matter if spacetime fits your definition of "real" or not?
      - 8note 6y ago
        Sabine's version of "real" - that the universe cannot exist without this is a better one imo Worm holes aren't real until we can't describe phenomenon without them. Same with the aether. Black holes and chairs are real because we can't make a theory that doesn't include them while still making accurate prediy
  - drran 6y ago
    Aether is real again as Higgs field. Speed of light in vacuum is variable again (gravitational waves). Vacuum is no longer an empty space.
    - drdeca 6y ago
      > Speed of light in vacuum is variable again (gravitational waves). Hm? Can you elaborate on this?
- jodrellblank 6y ago
  We have a photo of a building that makes accurate and measurable predictions of things like the roof being above the door, and how far, and which parts are transparent (windows) and which parts opaque (walls), and how many people could fit inside it. Is that picture as real as buildings get?
  - AnIdiotOnTheNet 6y ago
    Is your claim that the picture is the building? Because that's the equivalent of claiming that the a Penrose diagram is spacetime, instead of a representation of the model. The photo of the building is an accurate diagram of the model of that one individual building. It describes the building, it is not actually the building. However, your model (roof height, walls, location, etc) is the building. If that building is destroyed in a fire and remade to those exact specs, do we not say it is still a building?
    - jodrellblank 6y ago
      > "Is your claim that the picture is the building?" You said "a model which makes accurate predictions is as real as real gets". That the picture is the building is your claim here, that there's nothing more real than an accurate model, which I'm countering by absurdum. Wind can turn a turbine, a weather predicting model of wind cannot. You say "the differentiation [between a model and reality] is meaningless", I say a model is a leaky abstraction - when you send a single atom through a Young's double slit experiment and it interferes with itself and generates a wave interference pattern, that's leaking a reality outside the billiard-ball model of atoms, that's one time when the distinction between model and non-model is meaningful. > "If that building is destroyed in a fire and remade to those exact specs, do we not say it is still a building?" If the building is destroyed in the fire, and your model of it isn't, how can you say there is no difference between the building and the model?
      - AnIdiotOnTheNet 6y ago
        > You said "a model which makes accurate predictions is as real as real gets". That the picture is the building is your claim here, that there's nothing more real than an accurate model, which I'm countering by absurdum. My claim is that the model describes a real thing, not that it itself is a real thing, and the extent to which that thing being described is real is a matter of the accuracy of the model. You can model the motion of planets with geocentric epicycles, but that is less real than a model that uses heliocentric ellipses. Let me turn this around for a second: > when you send a single atom through a Young's double slit experiment and it interferes with itself and generates a wave interference pattern, that's leaking a reality outside the billiard-ball model of atoms, that's one time when the distinction between model and non-model is meaningful. Now ask yourself: if we have a 100% accurate model of physics that employs a concept of spacetime such that there are no leaks, no unaccounted for observations whatsoever, then would you say that it matters if spacetime is just some mathematical concept and the real mechanism works differently but produces exactly the same results? I submit that it doesn't. A model that produces perfectly accurate descriptions describes reality in so far as any description of reality can be said to. We don't have perfect models of reality, that is known, however lacking a more accurate model it is meaningless to say that our current ones (which are astonishingly accurate despite being imperfect) don't describe reality.

AnIdiotOnTheNet 6y ago

I'm saying the differentiation is meaningless. We have a model of space time that makes accurate and measurable predictions and that is as real as real gets.

Voloskaya 6y ago
So then the Aether was real for a while and stopped being real 200 years ago? If we discover a new model that makes better prediction than our current spacetime based model, just like relativity was to Newton's theory, will spacetime stop being real? The article was clearly using "real" with the definition we attach to it in our everyday language, not in deep philosphical sense.
- AnIdiotOnTheNet 6y ago
  > So then the Aether was real for a while and stopped being real 200 years ago? Yeah, pretty much. > If we discover a new model that makes better prediction than our current spacetime based model, just like relativity was to Newton's theory, will spacetime stop being real? In so far as Newtonian gravitation is also not-real. We still use that model for a lot of things of course. I don't know much about Aether theory or its predictions, so instead I'll use another long gone theory for my example: People used to model the motion of "heavenly bodies" using epicycles, complicated circles-within-circles patterns that assumed the Earth was the center of the universe and everything was taking a very complicated path around it. These epicycles were actually quite good at predicting the motion of planets and stars, so as far as anyone was concerned they were real. Some clever people eventually came around to the idea that all of that could be much more easily and more accurately modeled if we put the sun at the center. Of course we know today that that isn't quite right either. We don't, and possibly cannot, ever know if the models we use to describe the world around us are the most accurate or not. They are real when they work, because we have no better metric to determine their reality.
  - Voloskaya 6y ago
    I do agree with your point, but I think we are seeing the limit of language: when we don't attach the exact same definition to words, we can misunderstand each others while trying to convey the same thing. The way you use "real" is the way I would use "valid": A theory is valid until proven otherwise. And the way I use "real" (and I think it is the same way the article used it), is whether something has any grounding in our universe (some pattern as you said before). For example, wormholes are possible following the theory of general relativity, but we don't know if they are "real", e.g. can there actually be a wormhole in our universe. If we do end up finding one, then they are real. If we however find conclusive evidence that they cannot exist in our universe, then they are not real, but only an artifact of our (incomplete) theory of general relativity.
    - AnIdiotOnTheNet 6y ago
      > And the way I use "real" (and I think it is the same way the article used it), is whether something has any grounding in our universe (some pattern as you said before). Many of the things you described as "real" don't have grounding in our universe, i.e. things like "chair". It's possible I misunderstand your usage of the term "grounding". > For example, wormholes are possible following the theory of general relativity, but we don't know if they are "real", e.g. can there actually be a wormhole in our universe. If we do end up finding one, then they are real. If we however find conclusive evidence that they cannot exist in our universe, then they are not real, but only an artifact of our (incomplete) theory of general relativity. Sure, but how does that apply to spacetime? We know, so far as anything can be known, that space and time are two different perspectives of the same thing. Relativity described it, and we have measured and the effects it predicts with startling accuracy. Here's a question: It matters if wormholes can or cannot exist regardless of if the current model permits them or not. Does it matter if spacetime fits your definition of "real" or not?
    - 8note 6y ago
      Sabine's version of "real" - that the universe cannot exist without this is a better one imo Worm holes aren't real until we can't describe phenomenon without them. Same with the aether. Black holes and chairs are real because we can't make a theory that doesn't include them while still making accurate prediy
- drran 6y ago
  Aether is real again as Higgs field. Speed of light in vacuum is variable again (gravitational waves). Vacuum is no longer an empty space.
  - drdeca 6y ago
    > Speed of light in vacuum is variable again (gravitational waves). Hm? Can you elaborate on this?
jodrellblank 6y ago
We have a photo of a building that makes accurate and measurable predictions of things like the roof being above the door, and how far, and which parts are transparent (windows) and which parts opaque (walls), and how many people could fit inside it. Is that picture as real as buildings get?
- AnIdiotOnTheNet 6y ago
  Is your claim that the picture is the building? Because that's the equivalent of claiming that the a Penrose diagram is spacetime, instead of a representation of the model. The photo of the building is an accurate diagram of the model of that one individual building. It describes the building, it is not actually the building. However, your model (roof height, walls, location, etc) is the building. If that building is destroyed in a fire and remade to those exact specs, do we not say it is still a building?
  - jodrellblank 6y ago
    > "Is your claim that the picture is the building?" You said "a model which makes accurate predictions is as real as real gets". That the picture is the building is your claim here, that there's nothing more real than an accurate model, which I'm countering by absurdum. Wind can turn a turbine, a weather predicting model of wind cannot. You say "the differentiation [between a model and reality] is meaningless", I say a model is a leaky abstraction - when you send a single atom through a Young's double slit experiment and it interferes with itself and generates a wave interference pattern, that's leaking a reality outside the billiard-ball model of atoms, that's one time when the distinction between model and non-model is meaningful. > "If that building is destroyed in a fire and remade to those exact specs, do we not say it is still a building?" If the building is destroyed in the fire, and your model of it isn't, how can you say there is no difference between the building and the model?
    - AnIdiotOnTheNet 6y ago
      > You said "a model which makes accurate predictions is as real as real gets". That the picture is the building is your claim here, that there's nothing more real than an accurate model, which I'm countering by absurdum. My claim is that the model describes a real thing, not that it itself is a real thing, and the extent to which that thing being described is real is a matter of the accuracy of the model. You can model the motion of planets with geocentric epicycles, but that is less real than a model that uses heliocentric ellipses. Let me turn this around for a second: > when you send a single atom through a Young's double slit experiment and it interferes with itself and generates a wave interference pattern, that's leaking a reality outside the billiard-ball model of atoms, that's one time when the distinction between model and non-model is meaningful. Now ask yourself: if we have a 100% accurate model of physics that employs a concept of spacetime such that there are no leaks, no unaccounted for observations whatsoever, then would you say that it matters if spacetime is just some mathematical concept and the real mechanism works differently but produces exactly the same results? I submit that it doesn't. A model that produces perfectly accurate descriptions describes reality in so far as any description of reality can be said to. We don't have perfect models of reality, that is known, however lacking a more accurate model it is meaningless to say that our current ones (which are astonishingly accurate despite being imperfect) don't describe reality.