The tricky part with black hole spaghettification is that the slope of the gravity gradient (tidal force) can be pictured as exceeding 90 degrees within the event horizon, because there is no speed limit for the flow of space. This doesn't violate physics because Einstein's speed of light limit only applies to matter moving within space. This idea has been embraced by astrophysicists to explain inflation at the start of the Big Bang.

Why this matters is that when something spaghettifies, the particles at the end can never catch up to the ones at the beginning. The space between the ends of the spaghetti grows. Which also means that the spaghetti can never reach the pit at the center of the black hole, because the pit is farther ahead in its journey.

So our intuition that falling into a black holes means that we'll collide with the center is incorrect. If we could survive the journey, we'd see ourselves falling forever towards something growing infinitely farther away. Like trying to catch up with a falling elevator that's moving faster than we are.

From the outside, we see anything falling in as becoming 2D on the surface, red shifting as it accelerates away from us, becoming time dilated until it appears to freeze, never quite reaching the speed of light from our frame of reference. So even though it's being stretched along the radial axis and perspective should make it look smaller over time as our separation grows, it appears to stay the same size to us as it was when it entered the event horizon.

So a black hole can be thought of as an infinitely long tunnel to.. somewhere.

I prefer to think of it as a bubble which only grows internally. So in a very real sense, a whole universe is being birthed inside.

Unfortunately the math breaks down near the singularity, so maybe the particles do see themselves colliding with a pit. For example, the sun is 8 light minutes from Earth, so even if it was heavy enough to collapse into a black hole, it should still take 8 minutes to reach the center for a particle falling towards it, from its frame of reference.

But I don't think that's how it works. I think that the space flowing in faster than the speed of light overcomes spaghettification, creating a maximum strain inversely proportional to the mass of the black hole. Hawking hinted at this when he thought about what would happen to a human falling into a billion solar mass black hole whose tidal forces are weak enough that they're survivable.

-- edit: this paragraph is wrong, the universe behind also red shifts, which I realized after considering that the object's watch and ours are synchronized during free-fall --

Probably what happens is that the object sees the universe behind it speed up faster and faster as it blue shifts, until it ends in a white-hot flash the number of light-seconds away that the object began falling. Meanwhile the space ahead appears to expand in the same way as inflation, creating a pocket universe containing the mass which has already fallen in. Except that the universe behind appears to also red shift, due to the increasing distance between the object and anything behind. The expansion and contraction probably balance to create a microwave background at a temperature inversely proportional to the age of the universe inside. So the background inside might be hotter than ours since the black hole is smaller than the parent universe.

----

Also if nothing more falls into the black hole and it starts evaporating, matter inside will see previously fallen matter growing away from it. Just like how we see stars and galaxies moving away from us faster than the speed of light when their distance times the Hubble constant exceeds the speed of light, causing our universe to grow lighter and expand faster, which we perceive as dark energy. So matter inside would eventually see the perimeter rushing towards it faster and faster as the black hole loses its mass, with its internal Hubble constant growing larger and larger until the expansion of space rips the matter apart as energy, back into the parent universe as its mass falls beneath a few solar masses.

Which has implications for our universe, where instead of heat death, we re-experience spaghettification as the rate of the expansion of the universe keeps increasing until we explode. Or maybe the expansion only applies outside of our gravitationally-bound galaxy. So eventually the universe would only be our galaxy. But, I tend to think that evaporation still occurs, so even our galaxy would eventually be torn apart. But it would probably have already gone down the drain into the Milky Way's supermassive black hole, Sagittarius A*. In other words, the falling probably never ends. Which implies that maybe the universe is infinite, although we can never reach the parts moving away from us faster than the speed of light.

Until we invent warp drive or meet aliens or something. Just so everyone knows, I completely made all of this up, starting from first principles after watching a lot of PBS Space Time and How the Universe Works. But that's ok since astrophysicists don't have a reference to point to that disputes my unfounded claims yet:

https://jila.colorado.edu/~ajsh/insidebh/schw.html

Also, my description doesn't consider the quantum aspect of spaghettification, or how particles might behave inside gravitational barriers:

https://en.wikipedia.org/wiki/Particle_in_a_box

https://en.wikipedia.org/wiki/Quantum_tunnelling

I haven't found a clear summary yet for how the wave function behaves in a gravity gradient or under extreme time dilation, or when space is moving near or faster than the speed of light.

Shoot, I just realized something after writing this out. Two particles in free-fall without external forces should have synchronized watches. The object falling into the black hole may not actually lose synchronization with us. Does anyone know if that's correct?

https://en.wikipedia.org/wiki/Synchronous_frame

https://www.physicsforums.com/threads/question-regarding-tim...

If the clocks stay synchronized until the lead object reaches the pit, what happens if the pit is never reached?