Micro black holes, millions / billions of years?

[Nitox33]

Hello,

Always looking for answers to my questions,
I had some answers like what micro black holes
possibly created at the LHC (if it does not evaporate) would put millions or billions of years to be dangerous? I would like to know why

Sorry if I come to you
Ps : sorry for the way I did not have too many ideas !

 

[phinds]

I do not understand your question.

Micro black holes are believed to evaporate almost immediately and none are known to have been created at the LHC.

I have no idea what you are asking about billions of years.

Please try to restate your question in a more coherent way.

 

[Nitox33]

Hello,

You're part of a website response I got that
talking about millions / billions of years ... sorry for that
question, I had a hard time indeed formulate
"Moreover, even a black hole mini" stable "might remain for billions of years without absorbing the Earth" and yet another part of response
"a micro black hole would pass through the Earth and emerges on the other side without causing almost no damage. Because of its very small size. Smaller than an atom." (?)

 

[phinds]

Well, if a micro black hole DID last for billions of years inside the Earth, what it did would depend on whether or not it was at the gravitational center. If it was at the gravitational center, then it would just stay there without eating the Earth. If it was off-center and oscillated back and forth through the center then it would hollow out the center. If it were oscillating in a large enough range, it would eat the entire Earth.

All of that is rather silly, though, since it would NOT last for billions of years.

Yes, if it approached the Earth from a large distance, it would just pass through the Earth, possibly with very minor accretion of matter right at the line through which it passed through, and then it would just keep going.

 

[Nitox33]

Thank you for your answers, which helps to supplement my knowledge of this magnificent machine, besides, it normally reboot the 23March, at least for
testing, and May 18 for the famous 6.5 TeV collisions ...
Small subsidiary question, what would be the arXiv paper that might me
learn about the LHC and the famous micro black holes?

Another big thank you to you all and sorry if I ask too much questions ^^

 

[phinds]

I don't know what papers might help you. Perhaps someone else will answer. If not, you could start a new thread with that question.

 

[wabbit]

There are several papers discussing this, but you should note that they do not talk about ordinary black holes, the production of which would require if my memory is correct an accelerator about 1,000,000,000,000,000 times as powerful as LHC (actually one more zero I think but you get the idea), but about hypothetical black holes that might be produced (and immediately evaporate) if some exotic assumptions such as large additional spacetime dimensions were to hold (none were detected).

Somewhere to start might instead be:
http://press.web.cern.ch/backgrounders/safety-lhc.

 

[Borg]

I do not understand your question.

Micro black holes are believed to evaporate almost immediately and none are known to have been created at the LHC.

I have no idea what you are asking about billions of years.

Please try to restate your question in a more coherent way.

I believe that his question is a continuation of the questions in this thread - https://www.physicsforums.com/threads/the-lhc-will-climb-into-energy-some-questions.796413/

It was explained that high energy collisions exceeding the energy of the LHC have been occurring naturally for billions of years. It was also explained that IF a micro black hole was created, it would evaporate almost immeadiately.

Edit: fixed the link

 

[Nitox33]

Borg thank you for your answer but I is not the link
in question, it brings back to me Page subjects !

Can you repost the subject in question? thank you!

 

[mfb]

Well, if a micro black hole DID last for billions of years inside the Earth, what it did would depend on whether or not it was at the gravitational center. If it was at the gravitational center, then it would just stay there without eating the Earth. If it was off-center and oscillated back and forth through the center then it would hollow out the center. If it were oscillating in a large enough range, it would eat the entire Earth.

That wouldn't make a large difference. Even if stationary, a stable black hole (something we cannot produce at the LHC) could grow - it would catch the electrons and nuclei close to it, no matter if moving or not.

@Nitox33: Borg edited the link in case you didn't see it.

 

[phinds]

That wouldn't make a large difference. Even if stationary, a stable black hole (something we cannot produce at the LHC) could grow - it would catch the electrons and nuclei close to it, no matter if moving or not.

But if it were oscillating in, say, a 100 mile radius back and forth through the center, wouldn't it eventually eat out that whole region, or is it that it would accumulate such a small amount on each pass that even over millions of years it would not eat out the 100 mile radius sphere at the center of the Earth?

 

[mfb]

That depends on its size, something at the energy of the LHC would rarely catch an electron or hadron, not making "holes" at all. Either way, the core of Earth might be solid, but not solid enough to maintain holes at that pressure. The atoms would quickly rearrange, so the black hole would always be surrounded by matter independent of its motion.

 

[phinds]

That depends on its size, something at the energy of the LHC would rarely catch an electron or hadron, not making "holes" at all. Either way, the core of Earth might be solid, but not solid enough to maintain holes at that pressure. The atoms would quickly rearrange, so the black hole would always be surrounded by matter independent of its motion.

Good point. So the issue becomes one of how much would it "eat". If it eats enough, then even a modest-radius oscillation would eventually eat the whole Earth, but more likely I would think, it would settle in before then and just sit at the center.

 

[mfb]

Again: the motion would not matter. There are atoms at the center in the same way as there are atoms outside. It would continue to absorb matter at some size-dependent rate until the whole Earth is a black hole (with a runaway reaction once it reaches the size of a nucleon - sufficient to rip apart every chemical bond in its vicinity and to absorb every incoming nucleus).

 

[phinds]

Again: the motion would not matter. There are atoms at the center in the same way as there are atoms outside. It would continue to absorb matter at some size-dependent rate until the whole Earth is a black hole (with a runaway reaction once it reaches the size of a nucleon - sufficient to rip apart every chemical bond in its vicinity and to absorb every incoming nucleus).

Ah, got it. My idea of it sitting harmlessly at the center is clearly just wrong because the "center" would continue to compress from surrounding matter. I wasn't connecting the dots well. Thanks.

 

[Nitox33]

Oh thank you I did not see, I can not help but think of all that, scared silly and company, thank you again for your answers anyway and I hope not
being pushy with my questions!

Have a good week!

 

[Nitox33]

This anecdote , day or the LHC physics program resumes, I listen this playlist disco 70 '! :
https://open.spotify.com/album/29G8OGKPKrFrkOfZehbjXv :) ^^

 

[wabbit]

By the way I asked not long ago here in pf about when we might hope to produce black holes experimentally (this would be really interesting, and not that scary really, as was said before tiny black holes would evaporate so fast they would never be detected directly, only the products of their instant disintegration would), and the answer was very discouraging : at the very best, being wildly optimistic, we will need to wait several hundred years before we reach that technological capability (and it won't be in accelerators, these are far too puny)

 

[mfb]

By the way I asked not long ago here in pf about when we might hope to produce black holes experimentally (this would be really interesting, and not that scary really, as was said before tiny black holes would evaporate so fast they would never be detected directly, only the products of their instant disintegration would), and the answer was very discouraging : at the very best, being wildly optimistic, we will need to wait several hundred years before we reach that technological capability (and it won't be in accelerators, these are far too puny)

Well, there are some models where the LHC energy is sufficient. Exotic, but not impossible. We'll know more in a few months. Black holes are easy to search for.

 

[wabbit]

Well, there are some models where the LHC energy is sufficient. Exotic, but not impossible. We'll know more in a few months. Black holes are easy to search for.

Ah yes sorry you're right, I always forget those. Not holding my breath but that sure would be some exciting news.

 

[Nitox33]

I do not think he had many answers
thank you again anyway!

So Let 's hope this new RUN LHC our friend be successful :)
good week!

 

[stevebd1]

It might be worth pointing out that both spin (a) and charge (Q) reduce Hawking radiation (see equations 2.10 & 2.11 on page 19 of this paper) though the black hole would have to be virtually maximal (i.e. a²+Q²≈M²) in order for it to have any stability. See also the extended explanation at the bottom of 'What is Hawking Radiation'. Maybe if you had two particles hit head-on that were very slightly off centre, it's very remotely possible that a micro black hole with rapid spin and charge might be created, but as the black hole absorbed matter and grew, M would begin to increase over a and Q and the black hole would evaporate very quickly.

 

[Gary Feierbach]

A black hole at the center of the Earth of just the right size to evaporate and eat the Earth at the same rate would appear not grow. However, the heat generated by the evaporation radiation would heat the surrounding area and accelerate the feeding of the black hole so it's unlikely to remain stable for long. I would say it's a good bet there isn't one there right now.

 

[mfb]

Decreasing mass increases the radiation and decreases the rate of matter falling in - such a system is always instable, even ignoring temperature changes.

 

[Nitox33]

Again thank you for all your answers
Good week to all
* Goes on a motorcycle ...

* Subsidiary question, How to Read this famous opvistar page Cern?
It shows the status of the LHC and other facilities ...

I understand some but some others I can not seem to grasp the indications
-
http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php

 

[Gary Feierbach]

the evaporation time of a black hole is T_ev=5120*pi*G²M²/hc⁴
where G is the Gravitational constant, M is the mass of the black hole and h is planks constant and c is the speed of light.
A black hole with the mass of a small asteroid (radius of 120 meters) of 10¹¹Kg would last 2.7 billion years so there could be many of these dangerous entities around and we wouldn't know until it was nearly upon us. Perhaps the only way to detect these is by occultation of starlight

 

[wabbit]

But what would be the mechanism to produce such asteroid-mass black holes 2.7 bn years ago?

 

[Chronos]

Sub stellar mass black holes could only have been produced during the very universe to the best of our knowledge, hence the name primordial black holes ]PBH]. Not to worry though, there are far more energetic process than the LHC that occur - even in our own atmosphere. If teeny black holes were produced in such a manner, Earth [and every other massive body in the universe] would already be chock full of them. Since we do not see otherwise ordinary looking stars [or planets] winking out of existence, it is safe to deduce they do not possesses much of a threat.

 

[Gary Feierbach]

Can't high velocity obliquely colliding back holes create a 'mist' of smaller black holes.

 

[mfb]

@Nitox33: Please open a new thread for that question, as it has nothing to do with black holes.

the evaporation time of a black hole is T_ev=5120*pi*G²M²/hc⁴
where G is the Gravitational constant, M is the mass of the black hole and h is planks constant and c is the speed of light.
A black hole with the mass of a small asteroid (radius of 120 meters) of 10¹¹Kg would last 2.7 billion years so there could be many of these dangerous entities around and we wouldn't know until it was nearly upon us. Perhaps the only way to detect these is by occultation of starlight

If they would be frequent, we would see them "colliding" with stars or planets everywhere. The evaporation would also give a notable signal (if close enough), and nothing has been detected so far.

Can't high velocity obliquely colliding back holes create a 'mist' of smaller black holes.

No, it just gives a single larger, fast-spinning black hole.

 

[Gary Feierbach]

Another scenario is black holes created at big bang time that have evaporated down to asteroid size.

 

[Nitox33]

Ah, I see that our LHC friend had a "small problem" technique I allows me to
pass a link (in French, unable to translate here, sorry!)

http://www.futura-sciences.com/magazines/matiere/infos/actu/d/cern-redemarage-lhc-retarde-suite-court-circuit-57624/