Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum In response to Bill S. Are black holes real?

A report has been released which claims that black holes don't exist. I didn't really understand the report, other than the fact that the author of the paper has performed a mathematical analysis of the formation of black holes and decided that they cannot form. Specifically they claim to have shown that the mass loss is so large that black holes never form to begin with. On the Back Reaction Blog Sabine Hossenfelder discusses the report. She feels that the authors of the report has made some errors in the way they performed the analysis. For more we will have to wait until somebody follows up.

But the one thing that I really didn't understand was the exact meaning of "black holes don't exist". Well, we have some things out there that act like black holes. The one at the center of our galaxy for instance. So if black holes don't exist, what are those things?

Bili Gill

What can I say

If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.

Did I really ask if black holes are real?

I think you asked if the event horizon was real via the question about time near the event horizon.

You then get into an esoteric argument about whether an area of dense gravity without an event horizon is a black hole. GR predicts the event horizon but now you have some scientist lately like Hawking claiming it won't exist for various reasons and hence black holes don't exist.

They are what I call really stupid arguments because they miss the basic problem which was the problem I gave you and to repeat it

What is the smallest black hole you can have and why?

That answer is the most crucial in the argument because every argument made so far by every scientists gives no answer to that question. The latest AMS results show another problem with all current theories the evaporation rates are out by a really long way. It is really worth following the the comments of JaneHM in Lubos's article (http://motls.blogspot.com.au/2014/09/a-simple-explanation-behind-ams.html)

She solves the problem in an interesting way which I am not sure I agree with but it is at least a viable option


If we find the extra fundemental particles she is on a winner.

To be complete we should also say there is another possible answer that is that gravity isn't a Quantum field but an entropic force (http://en.wikipedia.org/wiki/Entropic_gravity). It's not popular as an idea but in the interest of discussion it's worth discussing all the options.

All current theories are out from experimental results so none of them are valid at what happens at what we call a "black hole". However GR is working brilliantly over a huge range within the universe and the only points it has trouble with is very small when it meets QM and at points of space that are black hole like. It is the only theory that covers that range and gives the correct answers so it is rightfully the standard science theory to use within those normal limits.

Any thoughts on Laura Mersini-Houghton’s work?

http://www.newsobserver.com/2014/09/30/4196212/unc-professor-pokes-theoretical.html#storylink=cpy

One thing she says that strikes a note of interest for me is:

“But the real motivation is that black holes are supposed to contain this singularity at the center, which is an incredibly exotic object. We can’t make sense of it with our physics.”

This seems to be another report on the paper that was mentioned on the Back Reaction blog that I linked in my first post above. It seems to be a bit more complete or at least it is more on my level. However I still don't know just what Mersini-Houghton means. Is she saying that black holes don't exist? Or is it just that our understanding of them is wrong? As I mentioned, there are a lot of things that look like black holes out there so I personally think that they exist. I can easily believe that our understanding of them could be wrong although I don't think it is very wrong. There has been too much work done on them, both theoretical and observational for us to completely upset our understanding.

As far as not making sense of it with our physics. That is a very true statement. GR tells us that there is a singularity, but QM tells us that there cannot be a singularity. To figure out what is really happening at the center of the black hole we will need to get a good theory of quantum gravity. Then maybe we will be able to make sense of it.

Bill Gill

She is fence sitting a bit like me and not going either way

I am willing to pick a side when LIGO reports it has detected a gravity wave which is the most likely result that is going to turn up in the near future.

If it doesn't detect a wave then I think it means the black hole situation is a lot more murkier than considered so far. For Bill, I don't think GR is under any danger in that situation it is holding far too well over a really large range but I think the GR dominant energy version black hole story goes up in smoke as there would have to be other important energy transfers involved and hence no wave.

I should also add the release of papers last week showing direct measurement of time dilation on ions at 71% the speed of light pretty much any theory that does not allow time dilation is dead in the water which I think includes most of the fringe alternatives to GR.

What I see is a situation very similar to when QM was considered to only happen at really small scales and people thought GR and QM would somehow collide down at some small scale. When macroscopic entanglement and QM effects were clearly shown, GR didn't become invalid things just got more interesting and we realized the two effects are present together at every scale.

I strongly suspect that there is the same possibility around black holes because a lot of the cosmological stuff right now is coming in at odds with hard lab based measurements.