100 Years After Einstein's Relativity, We're Still Just Figuring Gravity Out
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Maybe gravity will turn out to be just a computational artefact. The more energy and states in a volume, the "slower" progression of the [local] system. An effect like this could appear as curved space at energy concentrations. Perhaps GR could be derived from something like this?
Many people seem pretty confused when physicist talk about things like the black hole information paradox. We think that all physical processes are reversible which means that distinct physical states will always remain distinct. If state A and state B could or would evolve into the same state C this assumption would no longer hold because you could no longer tell whether you arrived at state C from state A or B. The laws of physics would not be time reversible.
And this is the sense in which physicist talk about information, the description of the state space. If you throw something into a black hole the only things that remain visible are things like the mass, the charge or the (angular) momentum but you just lost all the details about the thing you threw into the black hole which is a problem for our understanding of physics.
Why is that a problem? The information could still exist, it'd just be inaccessible...
This seems no different to me than a spaceship going beyond the Hubble horizon.
I can't actually do that experiment. And it turns out, when we got deep enough, we found out that things actually behaved differently (parity non-conservation).
When it comes to time reversal, we can't actually do the experiment, either, so we don't really know whether physics behaves the same when time is reversed. We expect, philosophically, that it will, but we don't know. But it seems to me, given how relativity mixes time and space, if physics is not the same with left and right reversed, then it can't be the same with time reversed either.
I think in the idea I mentioned up time would stop in black holes. All of the information would be preserved.
Anyways, not a physicist.
If we understand correctly, the universe is about 13.7 billion years old. I recall reading once that there is enough mass (matter plus dark matter) that the Swarzchild Radius of that much mass is approximately 13.7 billion light-years.
What if we're inside a black hole? How would that affect how we interpret what we see at large distances? (For example, does that explain the Hubble redshift? Does it explain dark energy?)
And, if it's true, then what is a black hole? Can you have a black hole inside the Swarzchild radius of another black hole?
Gravity as a force/phenomena in space on its own is actually very well understood. In fact it's possibly one of the most well understood theories we have in physics because of general relativity. However, at a particle scale we lack the understanding of how gravity would work.
Dark matter is the collective name for whatever "stuff" exists in the universe that we predict it should have, however because it is noninteractive in any way other than exerting a gravitational pull (it accounts for a lot of astrophysical observations that otherwise are bewildering given what we see in the universe). We know it should exist, we don't know what it is and can barely understand its current properties. So indeed, it is quite possible that it might be Aether-ish if we end up finding something else that explains our current observations or a drastic overhaul of how gravity works at large scales (the latter being very unlikely because of how well GR has stood up to experimentation so far).
With them, we can simultaneously explain lots of observed effects. But, as in the time of the aether, we know we don't have the whole story.
Relativity is only really useful in certain scenarios, people still calculate the motions of stars and galaxies with Newtonian physics:)
A minor point: it's "the Newton equation" or "Newton's equation", but not "the Newton's equation" (in the same way that one could write "the Eisenhower presidency" or "Eisenhower's presidency", but not "the Eisenhower's presidency").