Starship Asterisk*

Ann wrote:I'm too lazy to look it up now, but I'm sure Hawking said that the bigger a black hole is, the longer it takes for it to annihilate itself. For a black hole of a few million solar masses, we are certainly talking about trillions of years.

And since the universe is only ~14 billion years, the chances of a million solar mass black hole destroying itself appears to be zero.

Ann

We can always hope.

Ann wrote:I'm too lazy to look it up now, but I'm sure Hawking said that the bigger a black hole is, the longer it takes for it to annihilate itself. For a black hole of a few million solar masses, we are certainly talking about trillions of years.

And since the universe is only ~14 billion years, the chances of a million solar mass black hole destroying itself appears to be zero.

And the most massive black hole will eventually die gently, getting smaller and smaller until it simply disappears.

the universe we can see is 14 billion years old. Who knows if there is more

ta152h0 wrote:the universe we can see is 14 billion years old. Who knows if there is more

All of the Universe is 14 billion years old. There is almost certainly a lot more that we can't see, and never will.

dlw,
Hawking's own "Brief History" is most of what I know about BHs, and there he explains Hawking radiation that depends on the radius of the event horizon. The bigger the BH, the flatter that is and the less HR is released.
Conversely a microBH with a very curved surface releases lots of HR, diminishing its mass and the EH radius, in feedback, so that the final moments of a microBH would appear as a searing mote, but nothing on the scale of AsASSN-15lh.
And yes, Ann, as I undetsnd it, only a microBH could 'evaporate' like that, and they must have all gone long ago, there being not enough time in the Universe for a stellar B to do the same.

We have no idea what is inside the Event Horizon - the BH itself is a discontinuity in space-time, beyond any theory we have yet, and beyond any probe that could report back. So some kind of reaction cannot be discounted, but a BH is the result of a star that has exhausted its nuclear fusion fuel, and collapsed under it's own mass, that caused the extreme pressure and heat that started the fusion in the first place. That event is itself an enormous explosion, a type of Supernova - a hypernova? AFAIK, once a BH forms it cannot explode.

This video is one of many about BH formation. It's pretty dramatic and uses inappropriate language (the star chokes and coughs!) but the images rae good, and it includes The Bad Astronomer! https://www.youtube.com/watch?v=8grTbzAo0PA
JOhn

For those of you interested in going beyond the current standard thinking regarding black holes, there was an interesting article in Scientific American a few months back. It's a fun read:

http://www.scientificamerican.com/artic ... s-forever/

I have the issue, but it looks like the link isn't free. Nevertheless, with the issue info, perhaps you can get it at your local library, if interested.

I can't read the whole article, but the first paragraph is nothing new. Hawking describes the falling astronaut who, "would not feel anything special as he reached the critical radius [event horizon]" (Brief History, p.88) Would s/he see anything different? Would light be blue shifted there?
S/he will soon suffer spaghettification as tidal forces begin to pull her/him apart, but we could never see that.

John

JohnD wrote:I can't read the whole article, but the first paragraph is nothing new. Hawking describes the falling astronaut who, "would not feel anything special as he reached the critical radius [event horizon]" (Brief History, p.88) Would s/he see anything different? Would light be blue shifted there?
S/he will soon suffer spaghettification as tidal forces begin to pull her/him apart, but we could never see that.

John

No John, you're wrong.

The first paragraph of my print article says, "...we USED to think that an astronaut falling past the point of no return -- the so-called event horizon -- would not feel anything special."

[Emphasis mine on the operative word.]

The article goes on to describe something different than you are leading people to believe. You haven't even read the article. Make your case after you've read it -- or don't read it, and leave it be.

But don't imagine that the article merely repeats Hawking's POV, when you haven't even read it [and it doesn't].

And for those of you who are interested in the actual possibilities that new information is giving us the chance to ponder, the author, Joseph Polchinski states that what the astronaut might experience is instant death.

By the way, I'm not going to quote more from the article beyond the above (all from the first two print paragraphs), but I think they'd be okay with me quoting the title and subtitle, since they're part of the available info at the link (although the print main title is slightly different than the link main title): "BURNING RINGS OF FIRE - "Firewalls" of particles may border black holes, confounding both general relativity and quantum mechanics."

Apologies, speedreading above the limit!

But please messier, precis the contents in your own words. That's no offence to copyright.
I presume it takes the matter further than the previous SA article on the same subject: http://www.scientificamerican.com/artic ... hysicists/ ?

Will Bob get Anne back, or must he make a new life with Carrie?
John

[wild speculation]The host galaxy of ASASSN-15lh appears to be evolved and therefore metal-rich. But suppose the galaxy had a small, metal-poor companion. Suppose the progenitor of ASASSN-15lh formed in that satellite galaxy, and suppose the progenitor star was very massive and extremely metal-poor, therefore acting in ways we don't understand in our present metal-rich universe.

Suppose the star used up its hydrogen supply and evolved into a super-bright red giant, or an LBV. Suppose that it built a tremendous metal-rich core, but it never got as far as producing iron. Now suppose it began picking up more mass from a companion (or a gas cloud). And just suppose that this extra mass pushed the progenitor of ASASSN-15lh over the limit, not in such a way that it collapsed into a black hole, but rather, like a white dwarf picking up too much gas, it turned into a most terrible H-bomb (or He-bomb). What I'm trying to say is, what if the progenitor star was a supermassive star that was made to explode like a white dwarf star, but with dozens of times the mass? (I know... a white dwarf has a degenerate core, and the star I have described wouldn't have... but still...) [/wild speculation]

Ann

JohnD wrote:Apologies, speedreading above the limit!
But please messier, precis the contents in your own words. That's no offence to copyright.
I presume it takes the matter further than the previous SA article on the same subject: http://www.scientificamerican.com/artic ... hysicists/ ?
Will Bob get Anne back, or must he make a new life with Carrie?
John

Well, I still can't read that SA article, and messier isn't telling, but I can read New Scientist.
This week's issue has a report which I suspect is about the same papers as the SA one.

The BH Firewall Paradox says that the component of Hawking Radiation that falls in is entangled with what gets out, because information cannot be lost. All the particles are entangled, together.
But Quantum also says that entanglement can only be of a pair of particles.
Hence the paradox, and the result is the firewall at the Horizon.

Israel and Thanjuvur at Victoria U, British Columbia, resolve this by saying it is a personal firewall, for the observer, who must accelerate outwards to stay in place and observe the horizon. It's personal because a distant observer only sees low-energy Hawking radiation, which they say means that the particles aren't all entangled because the information was radiated back by the firewall in the first place, and no information got into the BH. No data in, no data out.

I'm going for a brain cool now, I think I have a firewall coming on.
John

Messier, are the two article congruent?

If Israel & Thanjuvur are right, isn't this a stab in the heart for Quantum?
John

John,

I haven't been around here much the last couple of days. Needed elsewhere.

You have the link and have chosen not to avail yourself. You may or may not have a nearby library and/or card. But I've discussed this to the extent I'm willing, and I'm trusting you to accept that.

Thank you for your understanding.

messier.palette wrote: The first paragraph of my print article says, "...we USED to think that an astronaut falling past the point of no return -- the so-called event horizon -- would not feel anything special."

[Emphasis mine on the operative word.]

The article goes on to describe something different than you are leading people to believe. You haven't even read the article. Make your case after you've read it -- or don't read it, and leave it be.

But don't imagine that the article merely repeats Hawking's POV, when you haven't even read it [and it doesn't].

And for those of you who are interested in the actual possibilities that new information is giving us the chance to ponder, the author, Joseph Polchinski states that what the astronaut might experience is instant death.

Dear Messier Palette,
since you emphasised a sentence of the first paragraph, let me emphasise the title "Black Hole “Firewalls” Could Change Physics Forever" and the subtitle "“Firewalls” of particles may border black holes, confounding both general relativity and quantum mechanics".

Both general relativity and quantum mechanics are incredible successful where they apply (in the "large" and "small", respectively). There is no experiment which is not described by them and both allowed precise predictions, which have been verified. In all our experiments/observations we did so far, we could ignore the influence of the other. We don't have experimental access to a regime where both have to be taken into account (e.g. a large mass, say that of the sun, compressed into a tiny space, say that of an atom). However, it is also long known that both theories, as we currently understand them, are incompatible. Theoretical calculations either yield infinites, inconsistent results, or paradoxes. The firewall paradox is one of them. To resolve it, we would need a theory of quantum gravity, which, alas, we don’t have yet. That is why the title uses the subjunctive rather then the indicative! I did not read the article in Scientific American, because it's behind a paywall. Does it discuss several different approaches to resolve the paradox or does it merely present one (possibly the author's?)?

Markus Schwarz wrote:Both general relativity and quantum mechanics are incredible successful where they apply (in the "large" and "small", respectively).

I completely ageee.

Markus Schwarz wrote:However, it is also long known that both theories, as we currently understand them, are incompatible. Theoretical calculations either yield infinites, inconsistent results, or paradoxes.

Yup.

Markus Schwarz wrote:I did not read the article in Scientific American

No problem. Your choice, quite rightly.

Markus Schwarz wrote:because it's behind a paywall.

Yes it is, as I mentioned when I posted the link.

You have the link and have chosen not to avail yourself. You may or may not have a nearby library and/or card. But I've discussed this to the extent I'm willing, and I'm trusting you to accept that.

Thank you for understanding.

Oh, brother. Just don't bother linking to articles with pay walls in the future. Find another reference... SA can't be the sole source of said theory.

geckzilla,
No idea if the NS article is about the same work as the SA one, but the coincidence makes it likely.
NS is paywalled same as SA, but I tried to summarise the NS one in my post above.
John

Chris Peterson wrote:

Ann wrote:I'm too lazy to look it up now, but I'm sure Hawking said that the bigger a black hole is, the longer it takes for it to annihilate itself. For a black hole of a few million solar masses, we are certainly talking about trillions of years.

And since the universe is only ~14 billion years, the chances of a million solar mass black hole destroying itself appears to be zero.

And the most massive black hole will eventually die gently, getting smaller and smaller until it simply disappears.

I dunno Chris. if it gets half as small then half as small - it may take an infinite amount of time...

geckzilla wrote:Oh, brother. Just don't bother linking to articles with pay walls in the future. Find another reference... SA can't be the sole source of said theory.

Geckzilla,

I posted a link to an article I thought might be interesting to people. I have it in print. Back issues might be available by phone although I don't know that. It's less than a year old and my library still has it.

I'm not a fan of buying online either, but I love to read physics (which is why I bought it in print).

If I had never heard of the article, I would have been grateful to hear of it here because I would have then had the opportunity to visit my library for it. And then, I probably would have called and ordered the back issue, if they are available from SA. (I don't know if they are, but I would have checked.)

So while I can promise never to contribute info at this forum again in the future, I did so a few days ago, as a rose-eyed newbie, because I thought it might be fun for some of you to read.

Yeah, sure, but then they tried to read it and tried to discuss it and you don't want to talk anymore and now you're apparently taking your toys and going home because we didn't all have fun like you wanted us to. Fine? Bye.

Geckzilla,

You asked that I not "bother" posting similar links in the future.

I agreed.

At my agreement, which possibly angered you further, you suggested I leave.

Agreed. I haven't been able to find a method to close my account, however, I've requested that the administrators close it. In addition, I've cancelled notifications and everything else I could find to cancel.

Although I don't have any "toys" to take "home," I've done as much as I can to comply with your request, with gratitude.

Why do you need me to close your account? Just don't log in. Whatever anger you think I'm feeling is actually just confusion. I don't know why you are acting like you care and then saying you don't care to discuss anything.

Messier.palette, I don't think you have done anything wrong. You are an interesting new voice here, and I hope you won't leave.

It's easy to make mistakes when you are a newbie. If you are willing to take some advice from me, then let me suggest that you try to get a "feel" for the sort of forum this is, and try to post in such a way that its members will find interesting. Do you want to share something that is behind a pay wall? I suggest that you painstakingly copy, word for word, the most interesting passages from the text you want to share. Another idea is to search for the article and the author on the net. Maybe there will be someone else out there who has quoted or commented on that article, and you can quote that.

At the very least, you should probably start by apologizing for the fact that the text you are referring to is behind a pay wall. Accept that most people here aren't willing to pay to be able to read articles on physics, but do please share your opinion that the text you refer to is extremely interesting. Then try to summarize what you find so interesting about it.

I will miss you if you leave.

Ann

Ron-Astro Pharmacist wrote:

Chris Peterson wrote:
And the most massive black hole will eventually die gently, getting smaller and smaller until it simply disappears.

I dunno Chris. if it gets half as small then half as small - it may take an infinite amount of time...

Zeno's paradox really doesn't work with black hole evaporation because when the hole gets half as small it's radius decreases at a rate four times as fast (i.e., eight times as fast relative to it's size). Radioactive material is only half as radioactive after a half life and would, in fact, (Zeno-like) last forever if not for the fact that there are only a discreet number of atoms.

Interesting conversation, but I don't think the physics of Hawking Radiation and evaporation times for BH have changed.
The current BH thermodynamics says the smaller the BH the hotter, and the faster emission / evaporation will take place.
T_evap ∝ Mass³
If small BHs were to ever exist, they would go out with a bang.

Wiki wrote: So, for instance, a 1-second-lived black hole has a mass of 2.28 × 10⁵ kg, equivalent to an energy of 2.05 × 10²² J that could be released by 5 × 10⁶ megatons of TNT. The initial power is 6.84 × 10²¹ W.