4d black holes

[sup2069]

Does anyone have a theory on what a 4d black hole would look like?

How different would it be from our own black holes if we were to get sucked into one?



I couldnt come up with my own theory, Im curious on what others may have to say.

[Geosphere]

They may not exist. Density / gravity will have different effects in tetra.

First, I think someone has to figure what one looks like in OUR dimension.

[sup2069]

Sure we have not seen a black hole in our realm, but we have an idea of what it would look like. Of course we could be wrong.

But a 4d black hole? I havn't been able to find any information on the theories of one.

[Jay]

I think they would be very similar to our black holes. They both would exist as singular points of extremely dense matter. The only difference would be that a 4d black hole would pull in objects from the w-direction too. And I guess it would warp the 5d fabric of tetraspace-time, as opposed to the 4d fabric of space time in our dimension.

[RQ]

maybe, maybe not...
we don't know squat about what gravity will do in 4D

[Yoshi]

maybe if we think of a 2-d black hole and compare with a 3-d black hole than it would be easier to compare a 3-d black hole to a 4-d black hole

[Geosphere]

I would like to introduce a posit.

Think about this.

What if a 2-D black hole appears to be a black hole in 2-D, but in truth is breaching to 3-D? And what if what we define as a black hole is actually a breach into 4-D, caused by a breakdown of quantum physics?

Could black holes, the locations where physics laws become irrational, be the crossing points to higher and lower dimensions?

OK, probably not, but just think about the 2-D hole breaching into 3-D and it gets interesting.

[Yoshi]

you cold be right and all, but i always thought black holes were collapsed stars.

[Geosphere]

They are. And if in collapsing, they end up putting matter in a 4th direction...

[alkaline]

Geosphere, that's an interesting idea :-) I don't know that it's actually necessary, but we don't really know enough about black holes to know it's not possible. The physics there are very extreme. Subatomic particles are very close together in black holes where in normal matter there is a lot of empty space.

[Yoshi]

Geosphere, that's an interesting idea I don't know that it's actually necessary, but we don't really know enough about black holes to know it's not possible. The physics there are very extreme. Subatomic particles are very close together in black holes where in normal matter there is a lot of empty space.

So close that it goes into another dimension?

[Geosphere]

spooky, huh?

[Yoshi]

how can it be spooky if i dont understand it?

[Yoshi]

oh yeh i forgot,

i like eh? better than huh?

[RQ]

But that wouldn't explain why black holes would explode.
When it fills up on matter, the black hole would just pop like a filled baloon. If the matter went into a different dimension, then black holes would be there forever. Perhaps they do go, yet stay, something like being in the 3d dimension just like we have 2D incorporated in us, yet having an extra dimension, but I wouldn't bet on that.

[Geosphere]

RQ, I've never heard of black holes exploding. Can you elaborate?

[Yoshi]

Rq

When it fills up on matter, the black hole would just pop like a filled baloon.

When a black hole fills up with matter, it gets heavier, and with more mass it would have a stronger gravitational force. Not pop.

[RQ]

It's a metaphor for what it actually does, it explodes, is that simpler?

[alkaline]

black holes don't explode. A supernova is a star explosion; later it turns into a black hole, which is more of an implosion.

[RQ]

Well, they don't collect mass until the Big Crunch happens, otherwise we'd probably be in one, since there must have been a lot more black holes in such a huge space (relatively compared to the size of a star) for there to have never been any black holes. The mere proof of the black hole death is the fact that we have a sun that is only 5-10 billion years old, and that there are other stars in the galaxy which we know don't last forever. Black holes might have infinite density, but the do have an event horizon, and they can only accumulate so much mass until they do burst out from the exit of negative mass, which only makes them heavier. I read somewhere that a black hole the size of a dot can suck in the whole Rocky Mountain mountain system. Surely it would then take a lot more mass since black holes are literally in empty space where there is nothing around them, a lot more time and mass, but the do explode after they get "filled up."

[PWrong]

Black holes might have infinite density, but the do have an event horizon, and they can only accumulate so much mass until they do burst out from the exit of negative mass, which only makes them heavier. I read somewhere that a black hole the size of a dot can suck in the whole Rocky Mountain mountain system. Surely it would then take a lot more mass since black holes are literally in empty space where there is nothing around them, a lot more time and mass, but the do explode after they get "filled up."

Are you talking about Hawking radiation? That's similar to what you're saying, so I'll try to clear it up a bit. If they don't suck in any extra mass for a long time, they eventually evaporate.

The basic idea is that a particle and an antiparticle appear out of nowhere because of quantum foam, and they're supposed to cancel each other out. But if they appear exactly on the event horizon, the antiparticle gets sucked in and destroys some of the black hole, and the particle flies out into space. So the black hole gradually becomes lighter.

By the way, most black holes can swallow suns, not just the Rocky Mountains.

[Geosphere]

Well, they don't collect mass until the Big Crunch happens,

Sure they do, at a fantastic rate. It is immediately converted to various radiation and density.

otherwise we'd probably be in one,

You bet - and of course that process is happening constantly, it will just take a few billion more years.

The mere proof of the black hole death is the fact that we have a sun that is only 5-10 billion years old, and that there are other stars in the galaxy which we know don't last forever.

No. This has nothing to do with proving anything. These processes take trillions of years.

Black holes might have infinite density, but the do have an event horizon, and they can only accumulate so much mass until they do burst out from the exit of negative mass.

Provide documentation for this. Are you trying to refer to White Holes or HawkingBarr Radiation?

I read somewhere that a black hole the size of a dot can suck in the whole Rocky Mountain mountain system.

Find better reading material - the planet would be decimated. Realize that a black hole the size of a dot is tremendous for a black hole.

literally in empty space where there is nothing around them,

No, they aren't. They actually fill that space and the spce consists mostly of Dark Matter anyway.

but the do explode after they get "filled up."

Provide documentation.

[Keiji]

the exit of negative mass

Isn't that exactly the same as entrance of positive mass? :?

[RQ]

No, because when two particles and antiparticles are created on the horizon, it's not the same when the antiparticle leaves (which it doesn't) and the particle enter the black hole. I looked up the information on Hawking radiation, and it said that indeed there is a way to observe black holes, although not the light which is emitted from the collapsed star itself, but a particle and anti particle are created at its event horizon, and there is a small but not nil chance that the particle would find a way out and into outer space, but the antiparticle destroys a particle in the black hole. I was pretty sure I read somewhere that black holes don't last forever. In the theory of everything Hawking mentioned that when black holes get filled up with matter so much that it almost is in the event horizon or something then negative energy leave the hole making it heavier until it bursts. He said one form of negative energy was the gravity between matter so it was needed more energy to separate the two.

[PWrong]

Hey, you're right, they do burst. I just read through "Black holes aint so black" in A Brief History of Time. Hawking says that as the mass of the black hole decreases, the energy increases, so it has to radiate faster to obey the second law of thermodynamics. He doesn't know exactly what would happen when the mass of the black hole becomes very small, but it would probably "disappear completely in a tremendous final burst of emission, equivalent to the explosion of millions of H-bombs".

This has to happen in a total vacuum though, because even background radiation would replace the enery emitted by Hawking radiation. Also, the particle falls into the black hole and the antiparticle escapes, not the other way round. So we were both wrong there.

[RQ]

I think it said something about both.

[PWrong]

Ok. So now we've cleared that up, what about black holes in 4D?

Would the equation for gravity would still be the same, (m1*m2*G)/d^2, or would it become (m1*m2*G)/d^3? The gravitational constant would probably have to be different to allow black holes to exist.

[alkaline]

yes, gravity would drop off with the inverse cube of the distance. I believe according to this equation, there are no stable orbits: everything spirals inward or spirals away. Thus everything would cluster into masses very distant from each other. Thus it is actually likely that everything in the fourth dimension is part of a black hole.

[RQ]

If matter had a very weak gravity, wouldn't all the atoms or clusters of atoms be as far as possible from each other?

[PWrong]

No, because gravity is already extremely weak at small scales. Atoms are held together by the other three forces: Electromagnetism, the strong force and the weak force.

Alkaline, does that mean gravity in 2D drops off with the inverse of the distance? I'm studying gravitation in physics this year, and most of the questions are in 2D, just for simplicity, but the equation is the same. Also, stable orbits are just 2D circles in the 3D universe, so why would the extra dimension have any effect?