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> The question here is whether spacetime is something like that, or if it is a proxy concept with no grounding whatsoever in the universe, but with good predict

> The question here is whether spacetime is something like that, or if it is a proxy concept with no grounding whatsoever in the universe, but with good predictive powers? Consider that "human", "chair", and "atom" are also just concepts are minds apply to certain patters of energy. We all "know what that is" because it is advantageous for our minds to place things in these categories for the purpose of modeling. You may know what a "chair" is, but there are an infinity of gradations between "chair" and any two other objects, like the beanbag chair sitting between "chair" and "pillow". The concept of a chair has no grounding in the universe, it's all in the mind. There are no physics that only apply to chairs. > For example, for a long time we believed that Aether filled space, and although we now know this is not the case, the mathematical model provided by the Aether theory was pretty useful. You could very well imagine a world where we know Aether is not real, but continue using it for lack of a better theory as it is a useful framework. Yes, that's how it works. When we have a better model we use that unless a simpler one will do. Newtonian gravitation isn't "real" by your definition, but we still use it in a lot of circumstances even though we have more accurate models.

Voloskaya 6y ago
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.

Voloskaya 6y ago

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.