# Debate: Do black holes exist?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by RJBeery, Aug 10, 2010.

Not open for further replies.
1. ### RJBeeryNatural PhilosopherValued Senior Member

Messages:
4,136

The "infinite" (unaffected by the local gravity effects) observer A knows that a rocket ship carrying passenger B is rapidly approaching the event horizon of a black hole* large enough to have negligible tidal forces in that region. Observer A calculates that passenger B shall cross the event horizon at t = infinity. The typical response to this is that, from B's frame, time passes normally and the cross-over of the event horizon is rather uneventful**.

HOWEVER (again from A's perspective) the black hole will dissipate due to Hawking radiation in a very, very long (albeit FINITE) amount of time. This means that passenger B's material structure will be calculated to be annihilated before ever crossing the event horizon. If this is true of passenger B and his rocket ship, it is also true of the material entering the black hole that preceded him. In fact, it's true of ALL material entering the region dating back to the very instant of the black hole's formation. In my mind this implies that the black hole is never formed, the event horizon never exists. All matter brought close enough together to form a traditional black hole is essentially "frozen in time" during its journey, being released from its fate in the form of radiation.

To me this makes intuitive sense as well for the following reason: as mass approaches the Schwarzschild radius it's material can be calculated to experience a velocity approaching that of c, yet relativity forbids any non-zero mass to travel at c. Perhaps Hawking radiation is simply another way of stating the conversion of mass approaching a velocity of c into energy.

Thoughts?

*I use the term "black hole" even though what I am proposing is a "black hole region" in which a proper black hole never quite materializes, yet powerful gravitational forces exist nonetheless.

** The point of this post is that B's journey would not be uneventful. In fact, I imagine as he approached the event horizon he would experience more and more frequent collisions with more and more energetic particles which would eventually destroy him and his ship entirely before his journey was complete.

3. ### RJBeeryNatural PhilosopherValued Senior Member

Messages:
4,136
No comments? Is there not a standard response to this proposal?

Messages:
269

7. ### RJBeeryNatural PhilosopherValued Senior Member

Messages:
4,136
NO1: I watched the video, very interesting eye candy, thanks. Gotta love Liam Neeson. It didn't really add anything to my understanding about the plausibility of my OP; does it for you?

8. ### NO1I Am DARKNESSRegistered Senior Member

Messages:
269
I've havent gone in depth about Black Holes yet. I havent the patients to watch a 20min. video either. I dont watch TV, just read. I just recently discovered & assumed that they are not proven to exist. That video, I seen parts, and it quotes 10's of thousand of black holes to exist. What for? Is it a gateway to to an alternate infinity? I imagined a universe as it is described like this: Stars are grouped into galaxy's which are grouped into the Suns neighbors ( nebulas etc ) < Galactic realms < Local Group < Supercluster and beyond that Super-Super Clusters. I just haven proven methods of transportation to move like a path vector protocol

9. ### cosmictravelerBe kind to yourself always.Valued Senior Member

Messages:
33,264
By whom? Can you provide a link? I thought they were already found to be there.

10. ### NO1I Am DARKNESSRegistered Senior Member

Messages:
269
I shouldnt have said discovered. I meant just assumed. sry :shrug:

When i say discovered, I mean that I see people refute it. Just like the OP = Debate, exist or not?

11. ### cosmictravelerBe kind to yourself always.Valued Senior Member

Messages:
33,264
They find that the gravity of the collapsing mass starts to disrupt the quantum vacuum, generating what they call "pre-Hawking" radiation. Losing that radiation reduces the total mass-energy of the object - so that it never gets dense enough to form an event horizon and a true black hole. "There are no such things", Vachaspati told New Scientist. "There are only stars going toward being a black hole but not getting there."

Dark and dense
These so-called "black stars" would look very much like black holes, says Vachaswati. From the point of view of a distant observer, gravity distorts the apparent flow of time so that matter falling inwards slows down. As it gets close to where the horizon would be, the matter fades, its light stretched to such long wavelengths by the dark object's gravity that it would be nearly impossible to detect.

12. ### RJBeeryNatural PhilosopherValued Senior Member

Messages:
4,136
cosmictraveler: AHH! What a perfect link! Vachaspati basically makes the same exact case that I do (except he's actually qualified to do it)...thanks

13. ### NO1I Am DARKNESSRegistered Senior Member

Messages:
269
SO let me get this right now. It is theorized that around the canter of a 'Black Star' the matters 'fades' and looses its light intensity ultimately circumnavigating the dark mass in the center, & *emitting as Hawkings Radition. But is it a Hole or is it a Star? A hole would imply a wormhole leading somewhere, but the mass that is gravitationally attracted to it, should it not speed up? I would imagine it being slow around a Star.

*

Last edited: Aug 10, 2010
14. ### RJBeeryNatural PhilosopherValued Senior Member

Messages:
4,136
Yes, the the rocket ship would "speed up" from B's perspective. But we are discussing what A would see/calculate. Relativity says that all kinds of funny things happen when A watches B's mass approach c (infinite flatness, clocks stopping, colors fading to nothing, etc)

15. ### SaquistBannedBanned

Messages:
3,256

That was fascinating.

16. ### DinosaurRational SkepticValued Senior Member

Messages:
4,768
GR equations indicate that a distant observer can never can see an object reaching or crossing the event horizon of a Black Hole. I think the equations are misleading & apply to a situation which never (or hardly ever) occurs.

I think the equations apply to a single particle or a very small object approaching an isolated Black Hole. Id Est: A Black Hole with no other matter falling toward the Event Horizon.

Consider the following.
• The size of the Event Horizon is a known function of the amount of mass inside the Horizon.

• Assume that a given Black Hole has MassX & EventHorizonX, while a Black hole with (MassX + DeltaMass) has Event Horizon (EventHorizonX + DeltaX).

• What do you expect to happen if DeltaMass falls within DeltaX distance from the original Event Horizon?

• The result of the above is a Black hole with more mass & a larger Event Horizon. Id est: The Event Horizon expands to include some of the additional mass falling toward the original Event Horizon.
The Event Horizon grows as matter falls toward it.

The distant observer never sees an object reach an existing Event Horizon, but he can observe a Black Hole growing as mass falls toward it. Id Est: The distant observer can see the Event Horizon expanding in finite time.

17. ### RJBeeryNatural PhilosopherValued Senior Member

Messages:
4,136
Dinosaur, you are trying to grant an exemption to Lorentz transform calculations near black holes. This should bother you. Your thoughts on "observing an event horizon grow as mass approaches it" PRESUME that the event horizon exists in the first place.

What we observe and what Lorentz transforms tell us are consistent everywhere else. What if B approaches the event horizon, flies around arbitrarily close to it, and then warps away to Observer A? They will find that B's clock did in fact slow down to a virtual stand-still. It's not an illusion. However, Lorentz transforms get weird when we ask what happens AT the event horizon. My OP suggests that the event horizon simply does not exist, with a possible reason why, and therefore the problem goes away.

18. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
The fact that they get weird'' is no evidence for the horizon not existing.

19. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
I don't know what the answer is, but I can see at least one gaping hole in your logic:

You haven't proved that B sees the black hole evaporate in finite time. If the only time that B sees the black hole evaporate is infinity'', then you're back to the original problem. In a near by'' reference frame, say a few light years away, there is no problem watching the rocket fall into the black hole, and then watching the subsequent evaporation.

You haven't proved that the mass ever experiences a velocity of c...there is no problem with velocities approaching c.

This violates the assumption that physics everywhere in the universe is the same. Particularly, if I perform an experiment near the horion of a large black hole, you claim that I would get something different, even though the structure of space-time is flat, as you yourself have admitted.

20. ### TheHandymanRegistered Member

Messages:
13
Black holes exist.
In massive quantities.
They do not evaporate.
They grow.
And not by absorbing mass.
They are not "black".
Well they are, but you'd never see the black unless it was exposed.
Soon enough, everyone will know.

Messages:
18,697
Evidence?

22. ### TheHandymanRegistered Member

Messages:
13
It's in the works.
The evidence for it is everywhere.
In time.

23. ### DywyddyrPenguinaciously duckalicious.Valued Senior Member

Messages:
18,697
Oh I see.
You're a crank.