engcat

No, the galaxaies are not "expanding." Galaxies are "moving away" from us. That Doppler effect is Slipher's observation. And yes they move away faster if they are farther away. The basis for the math of distances is the inverse square law to the brightness of light. So, we get non linear, progressively larger distances, or accelerated motion away from earth. The motion is uniform and universal. Hubbell concluded based on those findings that spacetime is expanding. Since this observed motion is based on inverse square law of distances, math can include a cosmological constant Lambda to explain it, and that is consistent with Einstein's tensor equation. An alternative view is that there exists dark energy which is responsible for the motion of galaxies which Slipher observed, away from the Earth. This would delete the Lambda cosmological constant, and would introduce some other "dark energy" matrices in the formula. Spacetime then would not be stretching (expanding). However, no one observed any matter or energy in the universe that is responsible for uniform and universal motion away from anything. So this hypothesis about dark energy is inconsistent with observation. Even though acceleration and gravity are indistinguishable in Relativity under Einstein's tensor equations. In there lies the problem, there is something within spacetime that distinguishes some accelerations from curvature (gravity). Hence, Lambda factor for spacetime itself, separate from G factor which is the curvature (gravity).

Flat refers to G in Einsteins equation, and G factor is about flat or warrped spacetime, locally. Here, the question is not about G but about Lambda, whether spacetime is static, contracting or expanding. Just a clarification on terminology. Since the time Einstein introduced the cosmological constant Lambda, it was discovered that spacetime is actually expanding and not static as Eistein thought. It is not contracting either. Whence the hypothesis about some dark energy that we cannot see but acts to expand the spacetime. In this world that constant is less than one for the purposes of Einstein's equation because spacetime is expanding according to observation. Can spacetime be flat and expanding as you suggest? Yes, only locally, roughly, it can be flat in areas with no mass in vacuum in accordance with G matrices, and it can be expanding in accordance with Lambda constant and observation.

That question is not unanswered. The word "curvature" means acceleration. It is proven that the universe is "accelerating," so there is indeed positive "curvature." In theory there are 3 options, but in real world only one of those three is observed, positive curvature.

Sure, why not? We do not know anything about black holes, so yes it is possible. The possibility can never be tested because we can never know anything about black holes. I presume a white hole would be a visible object as opposed to a black hole object which is invisible. I do not think it is possible that such visible object "white hole" is not in spacetime. Everything is in space and time so that object would have to be to, but it would be visible in some other frame of refence of space and time. As far as the axis, who knows? We do not know anything about black holes and cannot know anything. We just know that there is an object there, but it is located in curved space and time and light does not reach us so we can never see it and do not and cannot know anything about it.

Excellent. Now, what is waving? For example, in the case of sound, the air oscillates. The energy is in air pressure. The propagating wave carries the air pressure energy to transfer it to a remote microphone. In the case of water, the surface of water oscillates. The weight of water energy propagates and ultimately kicks the grains of sand on the shore. In the case of EM wave, does not quantized hf energy propagate in a wave to kick the electron and give it that KE? The wave part is all fine and dandy. The resonance is the mechanism. Fine. But, does not conservation of energy, hf = KE, require Einstein and others to say that hey, we are also dealing with quantas of energy for the sake of energy conservation?

We know that. Let's talk about the particle. Does the wave probability function apply to light? Wave probability function describes the probability of finding what exactly, when it come to light wave? Probability of finding what? The problem that was faced in 1800's was that light would cause "electrons to be emitted" from surfaces of materials, metals for example. The explanation was, there is an exchange of energy, quantas of energy between the EM wave and the surface, and this explanation of the exchange of quantas is the basis for quantum mechanics. Light is an EM wave but it also "behaves" like a particle, but since it has no mass but has energy it is called a quanta; light therefore behaves like a quanta of energy. Now what is your explanation that is in conflict with Einstein and this standard model and interpretation? How do you explain the emission of electrons and energy being transmitted in a wave?

I would like to focus on that part since we agree that radiation propagates like a wave. The issue is the quanta part. To that end, does the wave equation apply then to light at all, since without quanta we cannot talk about probability of finding it? Second, if light has no quantas then how do we detect it? Like how and what exactly do we see around us? What falls on our retina so that we can distinguish a coffe maker from the counter top for example. If it is just electron emission that is responsible for that, would there not be a continual loss of electrons. I think there are some issues that need explaining on the quanta part of things.

What exactly do you mean? Surely it is a quanta of energy? Do you mean that light is evenly distributed in an EM field and does not travel? How do you think light travels if it is not a quanta, if you think it travels?

Does GR gravitational constant not have constant speed of light? Does SR paper not say: "... and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c ..."? The topic here is the part about definite speed of light, not about frames of reference. The light is the topic, that part of sentence in the SR paper.

Then, if that is true, the theory says there are no local accelerated frames anywhere? Which would mean there are no local gravitational frames, which would mean that gravity is just a visual appearance from a local observer's viewpoint. Which we now is not the case, we know it here on earth, in the environment of the MM experiment. And that is a paradox.

I do. We know light accelerates because of gravitational lensing. That's the theoretical paradox with SR.

I don't get it. If paths and speeds of rods A and B coincide, what is relative about it?! The frames?!

In GR, by definition, by a rule, which is the equivalence principle, a light that follows a curved path is in an accelerated frame. Gravitional lensing proves. In SR, by definition, light cannot be in an accelerated frame. it follows a straight line! Which is it? It cannot be both.

And that's the point. So, if the the light accelerates in gravitational field, what is the point of Lorentz transformations and special relativity? Do those have any real application? I mean, we normalized everything to constant speed of light because it is invariant based on MM experiment, and that is the universal coordinate system in which we use Lorentz transformations, but in real life where light indeed bends, special relativity and its math gymnastics are meaningless. We could've just stayed with our own frame of reference and use Galilean transformations. It's the same thing as tying everything to speed of light which is arbitrary.

You don't know that. Object follow whatever paths and you do not know whether they are accelerating or moving at constant speed along those lines. Is the Sun an accelerating object, does it rotate at constant speed, or is it stationary? You do not know. Whatever you say, I can say something different, and my claim is just as good as yours, it's a guess.