Posts by 3ammo@qoto.org
(DIR) Post #A5dvMD568UaIilqMM4 by 3ammo@qoto.org
2021-03-27T18:00:52Z
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@freemo Now let's consider the symmetry thing.If we allow a *fundamental* theory to differentiate between directions (and in your case, it's even the same direction but with a negative sign) then we are building a very ugly *fundamental* view of the world. It's actually more than just ugly, we don't know where to go from there. In free space, we *postulate* homogeneity and isotropy and the isotropy of time as well. Because, why it be any different?Now, this is not really about the world any more. This is about *us* understanding the world. We have to build a simple model, then complicate things by adding stuff to it. That's how we understand anything. You may say "how do you know free is space is homogeneous and isotropic? Maybe it's not. Have you measured it?" I would say that free space is homogeneous and isotropic because I said so, not because of any measurement. Measurements can then be made within this model.If we make experiments that show that free space is not so symmetric, well then we will come up with another model of the world in which there is some other entity, more *fundamental* then space, and explain space in terms of that new entity. We will *postulate* that this entity is symmetric and that there are objects inside that entity that breaks the symmetry and produce a space that is not homogeneous and isotropic. If things are not simple, we just construct a deeper level of understanding, MAKE it simple and then explain complexity within it.
(DIR) Post #A5dvQwBGOobzkjyv8y by 3ammo@qoto.org
2021-03-27T18:01:55Z
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@freemo Thank you :)
(DIR) Post #A5dvUT30ep8SYYnvBQ by 3ammo@qoto.org
2021-03-27T18:02:27Z
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@freemo Then spam is what you get! :)
(DIR) Post #A5dxU1MLni2oaklWnw by 3ammo@qoto.org
2021-03-27T18:24:17Z
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@freemo Again, I am not contradicting what you said earlier (the round-trip speed of light is constant). This is not the point I’m arguing.You mention the use of Lorentz transformation. What is Lorentz transformation, how do you get it? You either derive it from the postulates of special relativity, there’s only two of them, the second one is that the instantaneous speed of light is constant in all frames, OR you can find it from a complicated and convoluted way from Maxwell’s equations, which also yield a constant instantaneous speed of light in all directions.The point I’m trying to make is that you talk about experiments as if they are objective and model independent. They are not.
(DIR) Post #A5dxe9YoAH9ivFQLPU by 3ammo@qoto.org
2021-03-27T18:26:45Z
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@freemo My point is not to pretend that the world is Newtonian, I simply meant our state of knowledge, our working theory was Newtonian. I was answering the question of "How do we prove relativity to be correct in the first place?" And that is by finding a contradiction between the Newtonian view and the measurements made within the Newtonian view.
(DIR) Post #A5dxyuzDXtzfnqg6kq by 3ammo@qoto.org
2021-03-27T18:30:30Z
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@freemo I get the point, I'm not missing it. But I am saying that it doesn't matter.A reality that is fundamentally hidden from us is not a reality at all.The points regarding symmetry are not moot. Our *understanding* of reality, measurements,...anything really, is impossible without these arguments.These are issues that we settle before and regardless of experiments and measurements.
(DIR) Post #A5dyvcH6l3XCr82HMO by 3ammo@qoto.org
2021-03-27T18:41:06Z
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@freemo Ok I think I get your point. Will reply over on the Einstein quote toot.
(DIR) Post #A5dz2jU8LizLFEWPOC by 3ammo@qoto.org
2021-03-27T18:42:23Z
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@freemo I'm really fine with that, I keep telling you
(DIR) Post #A5dzbNpgqOXGE77xCq by 3ammo@qoto.org
2021-03-27T18:48:39Z
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@freemo Yeah I'm writing the other reply. I think we actually agree in a certain sense. You want to call it a "convention" because of your view of reality as you explained it, I want to call it a "postulate" because of the way I see theory and reality. It's a philosophy discussion at this point (this is not meant to be disparaging).
(DIR) Post #A5e0dBSPvUVONWfEA4 by 3ammo@qoto.org
2021-03-27T19:00:11Z
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@freemo Because then everything is a convention, if we do it your way. Which is fine by me, all theories, in the end, *are* conventions. Any theory and any framework is a set of choices, these are postulate. You say that calling it a "postulate" says something about the true nature of things, or reality, but it doesn't. As long as you have a consistent set of postulates that can describe measurements, you have a working model of reality. But you can also have a different set of postulates that describe the same measurements. In that sense, all postulates are conventions. I prefer to keep the word "convention" for details within a theory, not its building blocks.
(DIR) Post #A5e144zi40de9W3qzY by 3ammo@qoto.org
2021-03-27T19:05:01Z
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@freemo Yes. Postulates are definitions. That’s what I keep trying to say. The speed is light constant “because we say so”. I repeated that multiple times. It is a definition, we don’t use the word “convention” for this kind definition, we use “postulate”. And that has nothing to do with any assertion about reality. Reality exists, but you can only see it through the lens of some model/theory. If you want a lens that says “in reality, the speed of light is different in different directions”, you can do that, and your measurements will agree with my lens that says “the speed of light is constant in general”. Reality doesn’t care about our definitions of space, time, velocities and how we communicate times and clocks. This is us, not the world.
(DIR) Post #A5e2zCUCyu4Xqg7zKC by 3ammo@qoto.org
2021-03-27T19:26:34Z
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@freemo But the general constancy in the speed of light is about more than making the math easier. As we discussed earlier here: https://qoto.org/@3ammo/105963064680177147, the "isotropy" of the speed of light is also directly related to our notions of space symmetry (among other things). This a statement about the world.On the other hand, I'm not sure how will gravity look like then, since the theory we use relies on spacetime being a 4D-space, that assertion needs Lorentz transformation to be the same everywhere in all directions (constant c). Again, if you wanna call all of that "just making the math easier", I can also agree because I'm fine with the idea, fundamentally, theories are choices of the way to see the world. But I'm assuming that you don't want that.
(DIR) Post #A5e6LyAafvThyCV5pA by 3ammo@qoto.org
2021-03-27T20:04:12Z
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@freemo I agree with both points, but you’re replying to things I’m not saying.Maybe I’m not clear. I’m not referring to the cosmological principle, nor am I saying the symmetry (short for homogeneity and isotropy) of space relies on the constancy of c.What I am saying is this: Given free space and no interaction between the observer and the light prior to the detection (both are reasonable assumptions), why would light behave differently moving towards an observer than away from them? A statement of this sort says something about the asymmetry of free space. Why? Because this is not really about light or sound or similar things, it’s about establishing a way to measure things in general, we must send signals to interact with distant objects. If light was like sound, the postulate would be “the speed of signaling is constant everywhere”.Why do we want space symmetry? Like I said, this is NOT about the cosmological principle and our large scale observations. It about our assertion that there must be a “reason” to differentiate one point or one direction in space from another. If that was not the case, then science (or even any communication) wouldn’t exist because simply being in a different place means there are different “laws” of physics, Of course, it’s not even a law of it changes every time we move.And the above paragraph is NOT about the measurement of the round-trip of light that will remain the same. You can’t even make that statement, let alone make a measurement, if the laws are different in each point in space without reason. So what is the reason? It’s any space dependent interaction. We start with completely symmetric clean slate, then add non-symmetric objects as space-dependent Lagrangian or whatever you choose to represent physics. It’s the first law of Newton “Things are the same (symmetric) unless there is a reason (force)”. Now, if you assert that light has different speeds in different directions (keeping round-trip measurements constant), then you have provide a reason, that is, some interaction theory. Fine, in THAT theory, you will have to assert the existence of a signal that propagates with symmetric speed: what we call light.Locality is another reason we have all this, in addition to the symmetry of space.You see, this is not really about light or measurements. You can’t measure anything without having a framework for interpreting such measurement. This is really deeper than just accounting for the constancy of the round-trip speed of light.
(DIR) Post #A5e6k7Z9ONcC3sVLRQ by 3ammo@qoto.org
2021-03-27T20:08:28Z
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@freemo Like I said, I'm not sure how that works. I have no reply until I actually carry out the construction of spacetime that way.
(DIR) Post #A5e7uUvHVSPlLsMsO8 by 3ammo@qoto.org
2021-03-27T20:18:24Z
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@freemo I don't like to refer people to books online. I'm not trying to be pretentious or imply that you haven't read the book.That said, if you check the first chapter of Landau & Lifshitz Mechanics, in the first few pages you will see his argument for the homogeneity and isotropy of space. Although I admittedly make more radical statements, this is what I have in mind when I insist on these kinds of symmetries and why I claim that we can't have science without them.Also I have not seen this argument in any other mechanics book, that's why I like to recommend this one in particular.
(DIR) Post #A5e7zcE1melXRoZp7Q by 3ammo@qoto.org
2021-03-27T20:22:39Z
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@freemo Yeah it's not about acceptance. I wanna do it myself to really see what assumptions will I be forced to make. There's always something to learn playing in the mud.
(DIR) Post #A5e8HxK25K9e5h8Apk by 3ammo@qoto.org
2021-03-27T20:26:00Z
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@freemo As I said, to keep the symmetry of space with asymmetric light, you have to have some theory to *explain* the asymmetry of light, just like out current theory explains the asymmetry of sound. In THAT theory, we must have a signal of some sort, that signal must be postulated to have constant speed in all directions: a de facto "new light".
(DIR) Post #A5eB6aqJccBx38VKoi by 3ammo@qoto.org
2021-03-27T20:57:29Z
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@freemo Okay, this discussion is getting a little bit out of hand for me.We have already established that we both agree we can have consistent descriptions of our measurements with anisotropic speed of light. This is not the issue.What I am saying is that we are not allowed to make statements like "In reality, c is anistropic, but whenever we measure it it looks like everything is symmetric". That statement is not forbidden because we have an experiment that contradicts it (we already established that it's compatible with measurements), but because it's logically incompatible with the framework we already chose. Why is logically incompatible? Because it asserts that there is a fundamentally anisotropic physical effect, without a theory behind it. If we decide to put a theory behind it, then that theory will have to conform to the symmetry *because we said so*. If it does, then it will have some isotoropic signal.If we allow arbitrary, UNDETECTABLE effects to enter the theory but have a way of canceling them out at measurement, then this more than just "making the math difficult". This is adopting a different theory, which gives us a different view of reality. Again, I am fine with that, but I wouldn't call it a mere "convention".I think I understand your points. I don't think I can explain mine better.
(DIR) Post #A5eD7gbbsguN7XH6hM by 3ammo@qoto.org
2021-03-27T21:20:08Z
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@freemo At this point I think we are in agreement. We just have different words.I’m not sure about your philosophical conclusions from that. Actually I’m not even sure about mine. But, for the time being, I have settled on “reality exists, but we have no access to it except through our mental models”. I can’t say the speed of light “in reality” is so and so, I can just create a theory/model and decide that c is constant in it, what I call a postulate and you a convention. In fact, the way I think of the principle of relativity is that it is not a physical theory at all, it is a requirement on science: the fundamental laws cannot change from one person to another, at least not without a dictionary. Of course, there’s more to be said, but I don’t think it belongs to social media post.Thanks for the interesting conversation!
(DIR) Post #A9j5X1lLGNkmiioh2e by 3ammo@qoto.org
2021-07-27T20:00:20Z
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Muselog #3 - Project RoamResources I used to setup Linux for audio and JACK settings. There are some xruns that I can't figure out, but it's fine so far.#linux #linuxaudio https://threeammo.neocities.org/muselog-3-linux-audio/