Strange

If your "first principles" includes the fact that the speed of light is invariant. This wasn't obvious until Maxwell, at which point it was only a matter of time until someone deduced the principles of special relativity. (Given time, Maxwell himself might have done it.) Here (and in fact, regarding geordief's question regarding elongation) you need to distinguish the physical effect from what is observed. The physical contraction would be described by the vector sum (so at 45o would be 0.7 of the contraction in the direction of motion). However, what you observe may be different (for example, an object moving towards you will appear elongated - effectively because of the Doppler effect; i.e. the different time it takes for light from the front and back to reach you). https://en.wikipedia.org/wiki/Terrell_rotation

The philosophical basis of what? If you are saying that, ultimately, everything is philosophical (after all, the nature of scientific knowledge is a philosophical question) then that is obviously correct and completely unhelpful. Given that we can and do draw a distinction between scientific knowledge (evidence, testability, etc) and opinion, I don't see how it can be correct to say that something that is determined by observation, experiment and theory is an "opinion". I don't really know what that means. Perhaps some context for where it came from, who said it, why, etc. would be helpful. (Or probably not if you are going to hijack this and turn it into yet another of your "what is relativity" threads - how many do you have going now?)

Saying that motion is observer dependent and not inherent in the object is physics, not philosophy. It is testable and measurable and so it is science, not opinion. Zero.

Why would they be different? There is no evidence that anything can escape from a black hole. And there are good reasons to think that nothing can escape. So this idea seems to be not just baseless but contradicted by current theory. And why the south pole? And how do you get a disk around the south pole? 1. If this dark matter were big produced at the centre of galaxies, why would it be at the outskirts of galaxies - how does it get there without passing through the rest of the galaxy. 2. Dark matter is fairly evenly distributed in and around galaxies, not concentrated around the outskirts. What does antimatter have to do with it? (We know dark matter isn't antimatter.) And nothing can travel faster than light. (And what would magically make it stop travelling faster tha light when it got to the edge of the galaxy?) There is an awful lot of "perhaps" here. And not much science. I guess you deserve some credit for trying to think of a way of testing the idea. If this were a serious hypothesis (not a theory) then you would have to quantify, using mathematics, what you would expect this extra gravity to be. Indeed. The mass of the supermassive black hole at the centre of our galaxy is estimated by looking at the orbits of stars around it.

No, it purely depends on speed not direction. A moving object is always contracted when observed from another frame of reference. If it is coming directly towards you, it might be tricky to measure its length in that direction, though!

I suspect that is because most of what you have read comes from popular science articles and is, therefore, extremely inaccurate or even wrong. https://arxiv.org/abs/0707.0380

Intersting point. I guess that is true. Clever idea. (Although, as already noted, Zeno's paradox is resolved by calculus, which allows you to determines the instantaneous velocity.)

That pretty much rules out quantum-scale things.

I would say that there is no such thing. However, the term can be used to refer to observations or evidence: https://en.wikipedia.org/wiki/Fact#In_science

It depends on what you mean by "object". Does that include neutrinos? Or photons? Things get more complex at the quantum level (as swansont has already noted) as we can't say anything about what happens to a photon, for example, between it being created at A and detected at B. We can assume it travels in a straight line, but that conflicts with things like the double slit experiment.

Because it is always possible that some new information or evidence will be found that shows the theory to be wrong. That is why all scientific theories are provisional. However well tested they are and however confident we are in them.

Impossible.

Yes, that's the word I was looking for! That is not how time is defined (although it seems to be an incredibly common idea). Time is a dimension, equivalent to the real spatial ones. That is why you need to specify 4 numbers if you want to meet someone. I'm not sure why.

Theories are never proved.

It is usually expressed as distance/second2 (the second derivative of position wrt time). But if you are measuring it from within a frame of reference (with no reference to anything external) then you would measure force as a proxy. I don't believe so.

Velocity is relative, acceleration is absolute (because you can measure it from within the accelerated frame of reference). No. As it can't occur in zero time, yes. And because velocity is the differential of position wrt time. And because we are dealing with 4 dimensional space-time.

What do you think about it?

Of course. That is why we have theories of relativity (whether Galilean, special or general). Change in (relative) position over time. They are both relative. The reason that special relativity specifies non-inertial frames of reference is because external forces (especially gravity) complicate things. Hence general relativity, which relaxes that restriction.

Because it gives the answers he wants, presumably. Or to put it another way: because numerology.

You can use the BigInterger.ToString method to convert it to hex. Extracting binary from hex is trivial.

Absolutely not. The motion of an object is not a property of the object. Motion, and related properties such as kinetic energy, are observer dependent. So one observer may say that X is moving east at 10km/s (with a corresponding kinetic energy) while another observer will say it is stationary with zero kinetic energy. Which is in inherent property of the object. All observers will agree on the mass. (Assuming we are talking about rest mass, which is what "mass" should mean). Plus the energy holding it all together.

And, as on Earth, you can see them when you get out of the sunlight.

I must have misunderstood this, then: Space expands when there is a uniform (homogeneous) distribution of matter. This is a result derived from the same equations that give us gravity. Where the distribution of matter is not homogeneous, then you don't get expansion. (Which is what is meant when we talk about galaxy clusters being held together by gravity). Newtonian gravity isn't really relevant. This all has to be modelled using GR. There is no force pushing things apart so this is not correct. John Baez has written a good explanation of the mathematics which I think you should be able to get something out of, even if you just skip the math: http://math.ucr.edu/home/baez/einstein/

Which is why it is obviously complete nonsense. You are mapping every word down to one of 9 possibilities. Therefore you can match any word with pretty much any other word (or close synonym). It is impossible to justify any conclusions reached on this basis. Apart from the fact that there is an completely arbitrary relationship between symbols and numbers. You would have to be insane to think this was a rational process for extracting information.

Neither dark matter nor MOND have anything to do with acceleration expansion. We don't know what causes accelerating expansion so the placeholder name for whatever the cause is, is "dark energy". Dark because we don't know what it is and "energy" because it can be most easily modelled by an extra energy term in the equations. But I thought that it was expansion that was puzzling you. You should get to grips with that before worrying about the extra detail of its acceleration.