Strange

I think you may be missing the point. There is an important distinction between a black hole and the early universe. A black hole exists within the universe. It is surrounded by (relatively empty) space. Things will fall in the gravitational field of the black hole. The early universe was entirely full of plasma. There was no concentration of mass. These are physically very different and very different in the effects they have on spacetime. Again, not the point I was making. When you fall through the event horizon, the centre of the black hole is no longer a point in space that you are moving towards. It is a time in your future. Similarly, the (notional) singularity in the big bang model is not a point in space, it is a time in your past. The existence of a mathematical singularity may mean that the theory doesn't apply at that point, but that is irrelevant. The centre of the black hole is a time in the future of any material in the black hole. The event horizon is no longer a location in space but a time in your past. So it doesn't matter if you turn into light, that light cannot go into the past so it cannot approach or leave the event horizon. It can only go forward in time towards the centre of the black hole. If you were to fire the engines of your spaceship to try and slow your fall, you would just get to the centre faster. I don't know what you mean by "constrained by light alone". The curvature of space-time in and around the black hole is defined by the mass-energy in the black hole. It doesn't matter if that is in the form of matter or photons or anything else. Light will be constrained to move along geodesics in space-time. These all go towards towards the centre. There is no other direction for light, or anything else, to go. Stuff is not held in the black hole by the force gravity. It is because there is no direction that is "out". Light has energy and momentum (not inertia, momentum). Let's try a few alternative ways of putting it: Energy and mass are equivalent. If all the mass in the black hole turned into light it would make no difference to the black hole. The gravitational effect of mass is defined (in the equations of GR) in terms of the equivalent energy. Mass does not appear in the equations, energy does. So if the mass turns into light, the energy will have the same effect as the mass did. Does that help?

Almost no ways. As matter fans to the centre of a black hole it will become compressed and therefore hot. It may form a quark-gluon plasma. But there are a couple of important differences from the Big Bang. In the early universe, the entire universe was completely full of a hot, dense plasma. The (mathematical) singularity was in the past. In a black hole, the hot, dense plasma is concentrated at one point in space. The (mathematical) singularity is in the future. I have no idea what that means. Energy is represented by energy in the stress energy tensor used the EFE. Inertia is one form, or definition of, mass. It doesn't appear in the EFE.

I can only assume, then, that you don't know what the words "objective" and "subjective" mean. You are making a purely subjective guess at intelligence, possibly influenced by the known date of birth of the person, and think that people should take you seriously for some reason. This is a science forum. Unless you can produce some objective (i.e. independently measurable) data instead of your guesses, no-one is going to take you seriously.

It is an interesting question. There are a couple of answers which, I think, are equivalent. One is that the expansion is a really tiny effect so even on the scale of the solar system it is too small to affect the gravity holding planets in their orbits. Certainly not enough to affect electromagnetic bonds in material bodies. The other thing is that the expansion only happens when the Einstein Field Equations are solved for a homogeneous distribution of mass. That is approximately true on cosmological scales but not when there're large lumps of matter around. So we shouldn't expect to see expansion locally. Gravitational waves are independent of, and unaffected by, the presence of matter and so the stretching and compression effects can be measured. (As you say, not by using a ruler which would stretch and shrink by the same amount, but by using the speed of light which is invariant.)

I don't know why you think radiation would behave any differently. It is still constrained to travel through space and time. The centre of the black hole is in the future, and even radiation cannot travel backwards through time. There're literally no paths for anything to ravel along that do not lead to the centre of the black hole. The gravitational effect of mass and energy are the same. Mass is represented in the Einstein field equations by the energy term.

You said you did it subjectively. Were you lying?

Because the maximum red-shift within the observable universe is not enough to make things undetectable. Nothing beyond the observable universe is observable. (The clue is in the name!) But it is reasonable to assume that immediately beyond the observable universe, things are about the same. Further out, who knows. I don't know if he did assume that. Do you have a source. He is often credited with the saying, “Only two things are infinite, the universe and human stupidity, and I’m not sure about the former” but he probably didn't say it.

Sorry, dimensions (I’m going to blame my phone)

It isn't. It has rotational symmetry about the y axis (which requires three degrees not two, to also answer the question in the title).

There would be a limit, I suppose, when the highest frequencies in the source have been shifted below what we can detect. But that won't happen for anything in the observable universe. We can never know anything directly about what is beyond the observable universe. I suspect we can never know if the universe is actually infinite or just very large.

That’s what I said: meaningless.

If that is true, then your correlation of intelligence with date of birth is meaningless.

That's not a bad analogy. The thing is, one could come up with a description of the internals that works perfectly but doesn't actually match what is in the box. As far as science is concerned, that doesn't matter; if you can't open the box all you want is a model that describes what it does.

Nice summary.

Don't think you said anything wrong. I just wanted to be sure you weren't misled by the article mixing up the cause of expansion and the cause of acceleration. Also, that you appreciate it is just one paper so we can't jump any conclusions about it yet.

A few things to note, expansion and dark energy are separate things. Expansion doesn't really need any further explanation. It happens for the same reason gravity does. we may get further insights into both of those from a future theory of gravity, but it won't change the big picture. BTW: The article is a bit misleading about this, mixing up expansion and dark energy. But from reading the original press release (I haven't had time to look at the paper, yet) the paper seems to be about dark energy (accelerating expansion) not just expansion. Acceleration of expansion is currently unexplained. Many people think that the vacuum energy (which gives rise to quantum fluctuations) should be the explanation - except it is massively too big. These guys think they have come up with an explanation for how most of it gets suppressed so just a bit "leaks out" to power accelerating expansion. It will need others to review and challenge this to see if it works. There is a very brilliant and very opinionated physicist who has blogged about this. He is not afraid to call well-known scientists crackpots if he thinks their ideas are wrong. However, he has some cautiously positive things to say about this paper (partly because he thought of the idea first!) so there may turn out to be something it. Which would be excellent. https://motls.blogspot.co.uk/2017/05/w-z-unruhs-solution-to-cosmological.html A model is something that works to describe the observations. It doesn't;t necessarily correspond to "reality" (whatever that is).

It is true that every potential outcome exists at the same time. In which case, you could consider each outcome to occur in different layers. Is it enough to layer just time? Would you have to layer space and time to allow the different physical outcomes to co-exist? Anyway, it sounds like you have come up with something pretty close to the Many World's Interpretation: https://en.wikipedia.org/wiki/Many-worlds_interpretation (Everett was a pretty smart guy, so well done for coming up with the same/similar idea!) [I'm not sure how entanglement would fit, so I won't comment on that bit]

You mean you believe it proves it false. You have not yet demonstrated any such proof, just claimed it.

Can I just check exactly what you mean by "validity" here. Do you mean the technical sense (that a logical argument is valid if the consequence inevitably follows from the premises, whether they are true or not)? Not necessarily true. There are some cases where that is true, such as the so-called "paradoxes" in relativity theory, which aren't paradoxes, just counter intuitive. But there are many paradoxes that can be expressed in formal logic (including the liar paradox) and therefore have nothing to do with intuition.

We already know exactly what information is lost (and how to recover it if, for example, we have two 2D images).

The same isn’t true for smoking. Smoking harms others, as well.

What is true? That it is coincidence? A bit hard when you refuse to answer (reasonable) questions. I am not in favour of jailing people for not vaccinating, but your argument doesn't make sense. You can't say it becomes a criminal offence (if one were to do that) only when insufficient numbers have been vaccinated. Public health policy doesn't work like that. For example, a proportion of people's blood pressure is raised by excessive salt intake. For some people salt has no significant effect. You can't only regulate salt in food (for example) or only target the health message at a subset of the population. You have to target the entire population. Take the smoking example raised earlier. It isn't guaranteed that smoking a certain amount will kill you. But it makes it much, much more likely that you will dies of related diseases. Some people will suffer no ill effects. You obviously can't target the "no smoking" message (including legislation, taxation, and other deterrents) at just the people who will get ill - you have to target the whole population. So the goal in vaccination policy might be to achieve, say, 90% instead of the (impractical) 100%. But you can't achieve that except by targeting 100% of the population. And yet another straw man argument. What happened to the "rational discussion"?

I think so. Light, for example, always has momentum, but no mass. (The amount of momentum is frame dependent, but can never be zero.)

There seems to be some twisted logic here: the act of not vaccinating only contributes to the (probability of) death of others therefore it doesn't matter. It won't directly cause the death of the person not vaccinated so why should they care. If they catch the disease, it isn't because they weren't vaccinated, it's because diseases spread; it's in their nature. Sounds a lot like the "climate changes anyway" denial of anthropogenic climate change. Or, "why wear a seatbelt, if your time has come [god has called you] there is nothing you can do about it."

Haven't they just been banned from taking part?