This notion of an aether has been integrated into physics for a very long time.
I was under the impression that the aether has been dead and buried in physics for a long time.
But, then again, I'm still not quite sure what
you mean by the "aether".
We are talking about the perfectly flat vacuum state of Quantum Field Theory. A perfectly flat vacuum state which refers to the quantum mechanical state of the vacuum. But is this vacuum considered a thing? Is it real even though it is not matter? I suppose it is, since how could it be in any given state if it wasn't real? It is real and it is called aether. Some call it the long winded vacuum state of quantum field theory, I prefer to call it what it has always been called: aether. [Since it harkens back to the idea of a fixed frame of reference, which can be misleading, the term aether isn't used much these days.]
Okay. So your "aether" is just the ground state of the quantum fields that exist
in spacetime. I can work with that.
Einstein's gravitational aether is the seat to an all relating process which he called spacetime.
What do you mean by "seat", in this context?
The aether was re-introduced early in the 20th century by scientists like Einstein, Mach, and Minkowski as they were trying to describe a substance, or... a thing.
The luminiferous aether was the hypothetical medium that was thought to be needed to carry electromagnetic fields. However, experiments failed to detect it. So these days, physicists hold that it's existence is not a necessary part of modern physics.
Einstein was well aware of the idea of the luminifeous aether. It didn't need "reintroducing" in 1900. It was quite a current idea in physics at that time.
Einstein said that matter and fields emerged from the same basic substance, that there could be no universe without an aether because it is the seat to the electromagnetic and gravitational fields.
It sounds like he was referring to older ideas, there, if he said that. (Where did he say it?)
That there are gravitational, electromagnetic, and nuclear forces because there is an aether.
Please explain how "aether" causes any or all of those "forces".
According to him, without fields there can be neither matter, nor spacetime, therefore the aether is.
This was just his thought-bubble musings, then? Or was there theory, maths - that kind of thing? Are we still back in 1920, here?
But this is not the same aether Newton, Poincare, and Lorentz talked about. Particles come to existence as required by spacetime's energetic and thermodynamic conditions. In this new aether, objects are relative to each other, not to absolute space, therefore there is no violation of the Principle of Relativity.
So the "new aether" is just a synonym for Einstein's spacetime?
As they explained Relativity, Einstein, Mach, and Minkowski said that things are not relative to absolute space, but to an absolute world.
"Absolute world"? Do you just mean the set of all objects in space? Is that what
they meant?
Acceleration is measured in relation to other objects in spacetime, not in relation to absolute space. According to Mach, this is why there is inertia.
Okay...
Einstein's gravitational aether does not represent an absolute inertial frame. It is not material, therefore cannot represent a background. It is not quantized, like material space.
What is "material space"? Is that just a synonym for "quantum fields"?
Are you just stating the well-known fact that general relativity is not a quantum theory, using somewhat obscure terms?
As Einstein said, spacetime is an extension of matter.
What did he mean by "extension", in this context?
That is because spacetime and empty space are not the same thing. Spacetime is neither primary, nor fundamental, it does not exist by itself, it is a product, just as matter and time are. There is flat empty space, then there is curved spacetime, or what is known as the observable universe.
The "observable universe", as I understand it, consists of spacetime
and its contents (matter, fields etc.) - but only the parts we can observe (hence the word "observable").
It strikes me that you seem to be a little confused about the distinction between spacetime and its contents.
Therefore the universe is background free and there is no fixed, nor absolute frame of reference. There is absolute reality.
It seem like a big step from "no absolute frame of reference" to "absolute reality".
What is "absolute reality"? That's not a term I'm familiar with from physics.
From Einstein's General Theory of Relativity we get that objects are not relative to empty space, they are relative to other objects with mass.
You're using the words "relative to" in a strange way, there. What do you mean by "relative to", in this context? What properties or features are "relative" and comparable?
Respect to Relativity, what is absolute is not empty space, what is absolute is the objective universe, the world.
What do you mean by "absolute" in this context?
You seem to be trying to distinguish something that is "absolute" from the opposite, which would be something that is "relative" to something else. What is it that you're trying to distinguish between?
This is what makes GTR (General Theory of Relativity) true, everything is related through and by the aether.
Related? How?
Or, how could it be that when a body is accelerated to near the speed of light, time and length must change in relation to a stationary observer?
The theory of relativity explains that as a reference frame phenomenon. If you like, you could say that it's due to the nature of spacetime.
Wasn't space supposed to be absolute, primary, independent, and not derivable from anything else?
When? Before 1905? I suppose that would be fair to say. There's been 100+ years of physics since then, though.
According to General Relativity, the universe is one single entity, one process.
You don't need GR for that. You don't even need physics. The word "universe",
by definition, means "everything that exists". It's had that definition for a long time.
Space... objects... Mankind... all come from one thing, which by definition, we call aether.
Is this just a convoluted way of saying that matter consists of quantum field excitations, or quantum strings, or something like that?
Einstein presented a different notion of the universe with his 1920 essay Ether and the Theory of Relativity. He stripped 19th century aethers off any kinematic or mechanical properties. This new aether lacked the property of motion and was not composed of parts which followed a time-line. What he termed the Gravitational Ether came from a completely different idea. Motion and particulation, he said, cannot be considered properties of the aether because it is one and has no components. This oneness can be used to explain action-at-a-distance, gravity, and inertia.
Einstein's aether is more akin to Newton's absolute space than most people think, this is why he sees the universe as background free but imbued with Mach's reciprocity between matter and space. It is Newton's absolute space mixed with Mach's aether, or with relativation. Empty space tells matter what to do and matter tells empty space how to curve. Which is where space curvature comes from.
Einstein said that, when trying to define the aether, we need to put aside notions of motion, extension, size, beginnings, and endings. In essence, he said that this substance lacks the properties of matter, yet all matter emerged and is ruled from it.
Okay.
So, this is all of some historical interest, I suppose.
Where are
you going with all this?
Is there anything you'd like to
discuss with us, here on sciforums?
Your posts read almost like you're cutting and pasting sections from a book - maybe one you wrote?
Please tell me this isn't just you trying to find a sneaky way to publicise yourself.