Could the Large Hadron Collider Create a Black Hole That Threatens Earth?

[mal4mac]

Physicsits didn't make the atom bomb, politicians did. It's all politics...

I just read Wheeler's intriguing biography "Geons..." and he says he was involved in building the bomb with a lot of physicist friends. He didn't mention that Churchill or Eisenhower got handy with a screwdriver...

Also no one forced the physicists to build the bomb. They decided to do it for their reasons -- political or otherwise.

 

[mal4mac]

You must be the biggest goof I've ever encountered that think that cosmic rays are high energy gamma rays...

I've encountered some very clever people who I would think, probably, do not know that. So why do attribute goofiness to the lack of recondite astrophysical knowledge?

cosmic rays consists of protons, electrons and ions which interact with nuclei in atmosopheric atoms at HIGHER CM-energy than LHC. It doesn't matter who and where you collide partiles, what matters is CM-energy. It doesent matter if you have two collding beams or a fixed target experimet such as the Earth beeing hit by protons acclerated from an AGN or SN.

That's your opinion, but not Martin Rees'. Why do you keep repeating this without saying this is your opinion, instead of making it sound like it is an absolute law of nature? I might let you get away with 'most physicists think'

 

[vanesch]

Do you mind if I copy it for my blog? :)

be my guest !

 

[malawi_glenn]

Yeah. Why don't they stick to the sensible stuff like ghosts descending the Earth and having it away with virgins?

Since ghosts are supposed to be supernatural and are not objects for the scientific method?

I just read Wheeler's intriguing biography "Geons..." and he says he was involved in building the bomb with a lot of physicist friends. He didn't mention that Churchill or Eisenhower got handy with a screwdriver...

Also no one forced the physicists to build the bomb. They decided to do it for their reasons -- political or otherwise.

It like saying that its not the politicians that kills people in war, because it is the soldiers. And it's also like saying that an atomic bomb is morally wrong. Why? Dynamite can be used for good things and bad things, it is the carachter of the person using it and his motives that matters.

I've encountered some very clever people who I would think, probably, do not know that. So why do attribute goofiness to the lack of recondite astrophysical knowledge?

Because he claims that he knows what cosmic rays are? It would be better if he asked what cosmic rays are, then he would be no goof.

That's your opinion, but not Martin Rees'. Why do you keep repeating this without saying this is your opinion, instead of making it sound like it is an absolute law of nature? I might let you get away with 'most physicists think'

Rees is referring to the saftey report made by cern, see an earlier post made by GerorgeJones yesterday. In that report, the cosmic ray argument is adressed.

 

[mal4mac]

Sorin,
The trouble here is that as physicist we know that there is a definite possibility of such an event occurring, but as Zapper already said it is as possible as you smashing a vase and the vase reassembling itself without your intervention. In physics this is a possibility so we cannot say the vase will definitely be destroyed, likewise we definitely cannot say that there is no chance of a black hole (or white hole [I'm sure there's some minute possibility of that too :)]) but we are incredibily more likely to be destroyed by something other than CERN, yes it could happen but there's a million other dangers in this world that are far more likely!

What is the possibility of a vase reassembling? It would guess it is a lot less than the 1 in 50 000 000 chance of planetary destruction that Rees put down in his book. So you are comparing unlike events,. The chance of winning the UK lottery is roughly 1 in 50 000 000 (with a carry over...) So that's a much better comparison event. Of course physicists are scared to use that, as people would be rather worried about a planetary destruction event occurring with the same probability as the lottery ticket they have just bought. So they make up fairy tales about vases...

 

[cristo]

Of course physicists are scared to use that, as people would be rather worried about a planetary destruction event occurring with the same probability as the lottery ticket they have just bought.

Did you read vanesch's posts above?

 

[mal4mac]

Since ghosts are supposed to be supernatural and are not objects for the scientific method?

I was referring to the "holy ghost". Maybe I made too many assumptions. If you are the same kind of church goer as Martin Rees you probably just go for a chat and don't actually believe in all that stuff (for this allusion check out Dawkins "The God Delusion").

It like saying that its not the politicians that kills people in war, because it is the soldiers.

Both are links in the chain, phycisists cannot push off theuir moral responsibility onto politicans.

And it's also like saying that an atomic bomb is morally wrong...

How is what I said like that?

Why? Dynamite can be used for good things and bad things, it is the carachter of the person using it and his motives that matters.

Because he claims that he knows what cosmic rays are? It would be better if he asked what cosmic rays are, then he would be no goof.

Maybe, through faulty education, he was convinced that cosmic rays are gamma rays, and didn't think he needed to ask. It seems unfair to call someone a goof because, perhaps, his physics teacher wasn't up to scratch.

 

[Orion1]

The Schwarzschild radius R_S of an (4+n)-dimensional black hole:
R_s = \frac{1}{\sqrt{\pi} M_p} \left[ \frac{M_{BH}}{M_p} \left( \frac{8 \Gamma\left( \frac{n+3}{2} \right)}{n+2} \right) \right] ^{\frac{1}{n+1}}

How do I transform this equation into Systeme International units?

Anyone here interested in examining Rossler's paper disputing Hawking Radiation?
[/Color]
http://www.youtube.com/watch?v=moEzECvJDas&feature=related"
http://arxiv.org/PS_cache/hep-ph/pdf/0106/0106295v1.pdf"
http://en.wikipedia.org/wiki/Micro_black_hole"
https://www.physicsforums.com/showpost.php?p=1844504&postcount=48"
http://en.wikipedia.org/wiki/Hawking_Radiation"
http://www.wissensnavigator.ch/documents/OTTOROESSLERMINIBLACKHOLE.pdf"
http://en.wikipedia.org/wiki/Otto_R%C3%B6ssler"

Leave, leave Geneva every last one of you,
Saturn will be converted from gold to iron,
RAYPOZ will exterminate all who oppose him,
Before the coming the sky will show signs.

 

[ZapperZ]

What is the possibility of a vase reassembling? It would guess it is a lot less than the 1 in 50 000 000 chance of planetary destruction that Rees put down in his book. So you are comparing unlike events,. The chance of winning the UK lottery is roughly 1 in 50 000 000 (with a carry over...) So that's a much better comparison event. Of course physicists are scared to use that, as people would be rather worried about a planetary destruction event occurring with the same probability as the lottery ticket they have just bought. So they make up fairy tales about vases...

The fairy tale here is that you are holding on to nothing else but this piece of information, AND, that you also have no idea how that number came about with respect to what kind of unrealistic assumptions that were made. So despite every other piece of information that contradicts that which has been published elsewhere, and despite the fact that Martin Rees has clearly revealed his objection on why someone would use such numbers blindly, you STILL stubbornly refused to learn and listen. You have already made up your mind and no amount of reasoning will change that, no matter that the fact that you do not understand how this single piece of information came about.

Vanesch has explained how one can come up with such numbers. Even Peskin has stated the level of assumption and speculation one has to make to make any kind of probability measurement (no matter how unrealistic they are) for such an event. If all of these somehow does not compare to this ONE number that you are hanging on to for dear life, then nothing will and you are wasting your time here in this forum.

And considering that this is the ONLY piece of information you rely on, I'm surprised that you still refuses to double check with Martin Rees if your opinion matches his. After all, he is the "horse's mouth". I would say there is a substantial odds (significantly more than 1 in 50 million) that he will tell you that you had understood it wrong. It is why you won't chance it.

Zz.

 

[ZapperZ]

Maybe, through faulty education, he was convinced that cosmic rays are gamma rays, and didn't think he needed to ask. It seems unfair to call someone a goof because, perhaps, his physics teacher wasn't up to scratch.

You should never pretend to know what someone else means. Here, it is YOU who has made him into a goof, because of all people, Martin Rees would never think that "cosmic rays are gamma rays". That's the silliest thing int he world to assume of him because he has heard of the high energy cosmic rays from the AGN's. The recent Auger Observatory results verified that these are NOT gamma rays.

I suggest you stop putting words into his mouth, especially when you haven't checked with him first.

Zz.

 

[vanesch]

What is the possibility of a vase reassembling? It would guess it is a lot less than the 1 in 50 000 000 chance of planetary destruction that Rees put down in his book. So you are comparing unlike events,. The chance of winning the UK lottery is roughly 1 in 50 000 000 (with a carry over...) So that's a much better comparison event. Of course physicists are scared to use that, as people would be rather worried about a planetary destruction event occurring with the same probability as the lottery ticket they have just bought. So they make up fairy tales about vases...

Look at an earlier post of mine in this thread. As I said earlier, Rees, nor anybody else, can give an ESTIMATE of the probability of earth-eating stuff at the LHC, simply because it is an unknown phenomenon, which, to about all of our theoretical understanding, is simply impossible. Objective probability zero. But one cannot exclude the possibility that totally unexpected things happen. Hence the need for upper bounds on eventual probabilities.

If you want to compare to the lottery thing, then a more accurate comparison (even though it remains an analogy), would be the following: you receive an enveloppe. Period.

Now, you start reasoning: IMAGINE that someone just sent me a ticket of the UK lottery ! Horray, I have a 1/50 000 000 chance of being rich now !

You open the enveloppe, and it is in fact a parking ticket. Nobody was going to send you ever a ticket of the lottery. The objective probability of you becoming rich by opening the enveloppe was actually 0. But, by making the assumption of having the lottery ticket, the best upper boundary you could find was 1/50 000 000.
If you would have done further inquiry, like looking at the finger prints on the enveloppe (and seeing that it were the fingerprints of the local police officer), you would have been able to lower the upper boundary of your chances of this enveloppe making you rich. But you stopped short of thinking of a UK lottery ticket.

 

[peter0302]

do we ? I'd say the jury is still out for that one for at least 50 years. How can you "know better" otherwise ?

Have we observed a nuclear winter ? So how do you know ?

Did MOST of them die ?

Did MOST people who took them, die ?

Did they ? Or did they just call themselves "barbers" ?

Any published papers about that ?

Any published papers about that ?

Look I spent 30 minutes on the phone yesterday explaining to my friend why there'd be no black holes. He was seriously worried. I don't blame him. Like I said, I blame the media.

And yes, CERN and others have done an extremely thorough investigation and should be thanked and commended. Let the atom smashing begin.

Let's just hope that when the next experiment in 20 years comes down the road, that catastrophic possibilities are not poopooed.

 

[mal4mac]

... despite the fact that Martin Rees has clearly revealed his objection on why someone would use such numbers blindly...

I gave a direct link to his book using Amazon "look inside" in this thread. How is this using his numbers blindly?

You have already made up your mind...

No. Still thinking...

And considering that this is the ONLY piece of information you rely on, I'm surprised that you still refuses to double check with Martin Rees if your opinion matches his.

I don't refuse, I'm just not inclined to bother the chap. I'm sure he'd rather get on with finding dark matter than answering my questions.

 

[ZapperZ]

I gave a direct link to his book using Amazon "look inside" in this thread. How is this using his numbers blindly?

Did you actually understood the derivation? Reading it, and understanding it, are two entirely different things. Many crackpots can cite stuff. Doesn't mean they understood what they are citing.

If you did understand it, then you would have seen why what vanesch said is utterly relevant here and you have have ceased making the same argument.

No. Still thinking...

You could have fooled me.

I don't refuse, I'm just not inclined to bother the chap. I'm sure he'd rather get on with finding dark matter than answering my questions.

Yet, you have no qualm in putting words into his mouth, or holding steadfast to something that even HE has said that has been misused. And you were expecting to have a rational discussion when you do that?

Zz.

 

[mal4mac]

Here, it is YOU who has made him into a goof, because of all people, Martin Rees would never think that "cosmic rays are gamma rays"...

Ooops the thread's got twisted, my goof, I should have quoted the original poster. I was not referring to Martin Rees, I was referring to an earlier post where a knowledgeable poster was calling another poster a goof.

 

[malawi_glenn]

What is the possibility of a vase reassembling? It would guess it is a lot less than the 1 in 50 000 000 chance of planetary destruction that Rees put down in his book. So you are comparing unlike events,. The chance of winning the UK lottery is roughly 1 in 50 000 000 (with a carry over...) So that's a much better comparison event. Of course physicists are scared to use that, as people would be rather worried about a planetary destruction event occurring with the same probability as the lottery ticket they have just bought. So they make up fairy tales about vases...

And does a popular science book have more authority than published reports?

 

[malawi_glenn]

I was referring to the "holy ghost". Maybe I made too many assumptions. If you are the same kind of church goer as Martin Rees you probably just go for a chat and don't actually believe in all that stuff (for this allusion check out Dawkins "The God Delusion").

Dawkins is a joke with no academic profession in neither philosophy nor theology... It's like having a professor in biology commenting the dangers about LHC..
I recommend Polkinghornes books, 25years professor in theoretical particle physics at cambridge, and now priest in anglican church ... if you want an update and mature view on science vs. religion.

Both are links in the chain, phycisists cannot push off theuir moral responsibility onto politicans.

If the government didn't wanted the atomic bomb, then phycisists could not build it. You don't build mass destruction weapons on your own you know, the government approved. It's like your child asking to build a bomb, but have no money nor authority to do so, then if you give your child both money and authority to do so, who's fault is it that a bomb is beeing made?

Maybe, through faulty education, he was convinced that cosmic rays are gamma rays, and didn't think he needed to ask. It seems unfair to call someone a goof because, perhaps, his physics teacher wasn't up to scratch.

enmerkar says he is a scientist, and he uses many quite advanced physics-words, he can't blaim potentially bad teachers for that misstake.

And have you read the saftey report from Cern yet?

 

[mal4mac]

And does a popular science book have more authority than published reports?

Depends on who's writing the book...

Are you seriously suggesting that Rees would just make things up in a popular book?

 

[malawi_glenn]

Depends on who's writing the book...

Are you seriously suggesting that Rees would just make things up in a popular book?

You don't use popular science book when entering a discussion with physicsists ;)

 

[cristo]

Aren't we going somewhat round in circles here?

 

[mal4mac]

Dawkins is a joke with no academic profession in neither philosophy nor theology... It's like having a professor in biology commenting the dangers about LHC...

I'm reading an excellent book at the moment called "Medieval Philosophy" by Sharon M Kaye, associate professor of philosophy, and who does she recommend for 'a modern critique of teleology"? That's right, The God Delusion by Richard Dawkins. And that's just the book I happen to be reading today! He has plenty of support from serious philosophers.

I recommend Polkinghornes books, 25years professor in theoretical particle physics at cambridge, and now priest in anglican church ... if you want an update and mature view on science vs. religion.

There's always one... You might like to check Dawkins' figures for the number of believers amongst Nobel prize winners (and Polkinghorne isn't anywhere near a Nobel prize winner! I read his v. short book on QM. I wish it had been shorter...)

 

[malawi_glenn]

I'm reading an excellent book at the moment called "Medieval Philosophy" by Sharon M Kaye, associate professor of philosophy, and who does she recommend for 'a modern critique of teleology"? That's right, The God Delusion by Richard Dawkins. And that's just the book I happen to be reading today! He has plenty of support from serious philosophers.



There's always one... You might like to check Dawkins' figures for the number of believers amongst Nobel prize winners (and Polkinghorne isn't anywhere near a Nobel prize winner! I read his v. short book on QM. I wish it had been shorter...)

And there is always one philosopher liking Dawkins ;-)

A person who thinks that a nobel prize in physics makes them authoritized to make claims about philosophy or religion is a goof. Myself, who is semieducated, enjoys to dissert Weinberg and C.O's "arguments" against relgion.. maybe we should continue this debate somewhere else? this is off topic

 

[peter0302]

This may be the first thread in history that I'd advocate locking. But I'll second the motion.

 

[Almanzo]

Let us not forget that the LHC has at most 14 TeV at its disposal (but actually much less for the elementary collisions of the partons) which corresponds to at most the weight of 10 000 protons. That's very tiny for a BH ! Much much much smaller than the size of a proton. So IF these things interact with a proton, they won't eat up all of the proton, but just maybe one quark of it... and hence liberate a pion.

Is this what would happen? Quarks have partial charges, so in devouring a quark the hole would acquire a partial charge. It would only become neutral again by (electromagnetically)attracting the other quarks from the proton, and afterwards the other particles from the atom. So I would expect a point-sized black hole which manages to hit any part of an atom to end up devouring the whole atom.

Its probability of doing so would be the cross section of the particles divided by the cross section of the atom. Roughly 1/100.000 squared or one in ten billion. To devour one atom it would have to pass through ten billion layers of atoms, or roughly 10 centimeters of solid material. Passing once through the Earth, say ten thousand kilometers of material, it would devour one hundred million atoms, and multiply its original mass by ten thousand. If it started at nearly lightspeed, it would still have a speed larger than 10 km/s. But if it started at nonrelativistic speed, it might not re-emerge.

 

[Vanadium 50]

Did you actually understood the derivation? Reading it, and understanding it, are two entirely different things.

Ever see A Fish Called Wanda?

Wanda: But you think you're an intellectual, don't you, ape?

Otto: Apes don't read philosophy.

Wanda: Yes they do, Otto. They just don't understand it. Now let me correct you on a couple of things, OK? Aristotle was not Belgian. The central message of Buddhism is not "Every man for himself." And the London Underground is not a political movement. Those are all mistakes, Otto. I looked them up.

At some point, one simply has to give up. How do you argue with someone who thinks that the CERN safety committee is deliberately lying? How do you argue with someone who won't read that report? Or someone who won't even read the part of the thread where his concerns are addressed? There are people out there who simply cannot be convinced.

 

[azzkika]

as an under educated neutral, i find it fascinating how diverse opinions can be across the scientific world on this subject. hopefully this l h c will reduce the diversity of opinions with greater understanding.

those who are most sceptical about safety must be heard, i remember watching a program called 'absolute zero', and it mentioned how many laboratory assistants or professors were seriously injured in the process of their experiments. we have seen the power of splitting the atom, so what power we may unleash by potentially splitting other parts of the atom does hold some trepidation for me, as even if the experiments are safe, the weapons they may derive certainly won't be.

 

[Vanadium 50]

But the point is that there is very little diversity of opinion on this. The number of particle physicists - the people who are most capable of assessing the risks - insisting that this is unsafe appears to be precisely zero.

There are risk associated with this. Falls and electrical hazards are among the most serious. But a world-ending black hole is not one of them.

 

[jms5631]

But the point is that there is very little diversity of opinion on this. The number of particle physicists - the people who are most capable of assessing the risks - insisting that this is unsafe appears to be precisely zero.

Exactly the point...I have yet to find a single mainstream particle physicist who is concerned about the safety at the LHC. I've heard from a chemist, a card carrying botanist, a science fiction writer, and scores of paranoid laymen without any science background to speak, but yet to hear from a rational person with any credentials. I'm sorry, but Martin Rees does not qualify as someone concerned about its safety...he has enthusiastically articulated his position of suppport. This thread seems to be going nowhere. Despite the ardent efforts of Zapper Z and Vanesch among others, those few seem to be entrenched in their unfounded paranoia, and no amount of scientic rationality is going to pull them out of it. No matter what context you put "1 in 50,000,000" some people simply won't listen and will continue to use it to justify their perseverations.

Regarding Dawkins: one of the main points of his book was that religion is not a province that only theologians are specifically equipped to handle, and that science and reasoning can put an objective probability statement on God's existence, if not disprove him outright. I thought it was a remarkable book, and surely not worthy of anyone's outright dismissal(unless, of course they feel threatened).

 

[vanesch]

Its probability of doing so would be the cross section of the particles divided by the cross section of the atom. Roughly 1/100.000 squared or one in ten billion.

That would be a very high cross section, and if that were the case, then, per astrophysical argument, not just all neutron stars, but probably even all asteroids would already have been transformed into black holes. First of all, it is usually wrong to use the "geometrical" cross sections for this kind of interactions, but even then, you took the geometrical cross section of the nucleus (which is of the order of a 1 fm) - while you should take the geometrical cross section of the black hole - which is of the order of 10^-30 m (I should check but it is the Schwarzschild radius of the mass of 10 000 protons). Now, that gives you a tiny surface: about 30 orders of magnitude smaller than the nucleus surface. So if we can use geometrical arguments, it should interact about 10^30 times less than your estimation here. That said, we don't know what is the real cross section of a micro BH, because in order to even create one at the very low LHC energies (for gravitational phenomena), spacetime has to be very special, and theoretical speculation is abound.

So it might be as large as you say. Or it might be even much smaller than I say. Anyone's bet is ok. In fact, we have no theoretical model of such a BH at all, because all theoretical BH we know should emit Hawking radiation.

Also, your argument about it being charged and hence gobbling up the whole atom is not correct. It would simply become an ionizing particle. Otherwise, your argument would also stop any possibility of ionizing an atom with any radiation, as the "rest of the charge would follow". But again, it might be possible for very peculiar BH (as they aren't of the kind theorists have thought up, everything is possible now).

To devour one atom it would have to pass through ten billion layers of atoms, or roughly 10 centimeters of solid material. Passing once through the Earth, say ten thousand kilometers of material, it would devour one hundred million atoms, and multiply its original mass by ten thousand. If it started at nearly lightspeed, it would still have a speed larger than 10 km/s. But if it started at nonrelativistic speed, it might not re-emerge.

Again, if it had such enormous cross section in its interaction with matter, any such freely traveling BH would immediately transform each stellar body into a BH. We wouldn't be here in the first place.

EDIT: ah, I think I see your argument now: you seem to think that if a BH crosses a nucleus, it "must" absorb it, no matter how small the hole. But on the BH's scale, the nucleus is not a "massive filled thing", in the same way as for a fast electron, the atom is not a massive filled thing".

What you estimated was roughly the probability of a NEUTRON to interact in matter.

 

[malawi_glenn]

I'm sorry, but Martin Rees does not qualify as someone concerned about its safety...he has enthusiastically articulated his position of suppport. This thread seems to be going nowhere. Despite the ardent efforts of Zapper Z and Vanesch among others, those few seem to be entrenched in their unfounded paranoia, and no amount of scientic rationality is going to pull them out of it. No matter what context you put "1 in 50,000,000" some people simply won't listen and will continue to use it to justify their perseverations.

Well we can always hope that people are reading the saftey reports and that we save a few. Guys who already from the beginning don't know a thing about neither physics nor how to read reports, like mal4mac and enmerkar, will perhpas not change their opinion - but that is their problem. If they want to live in and spread ignorance, it's up to them.

 

[Orion1]

If the fundamental Planck scale is ≈ 1 TeV, LHC,
with the peak luminosity of 30 fb^−1/year will produce
over 10^7 black holes per year.

The Schwarzschild radius R_S of an (4+n)-dimensional black hole:
R_s = \frac{1}{\sqrt{\pi} M_p} \left[ \frac{M_{BH}}{M_p} \left( \frac{8 \Gamma\left( \frac{n+3}{2} \right)}{n+2} \right) \right] ^{\frac{1}{n+1}}

How do I transform this equation into Systeme International units?

Anyone here interested in examining Rossler's paper disputing Hawking Radiation?
[/Color]
Reference:
http://www.youtube.com/watch?v=M3iMX8xzofc&NR=1"
http://arxiv.org/PS_cache/hep-ph/pdf/0106/0106295v1.pdf"
http://en.wikipedia.org/wiki/Micro_black_hole"
https://www.physicsforums.com/showpost.php?p=1844504&postcount=48"
http://en.wikipedia.org/wiki/Hawking_Radiation"
http://www.wissensnavigator.ch/documents/OTTOROESSLERMINIBLACKHOLE.pdf"
http://en.wikipedia.org/wiki/Otto_R%C3%B6ssler"
http://www.youtube.com/watch?v=Kf3T4ZHnuvc"
http://www.youtube.com/watch?v=PR2OLjAr1Fc"

Leave, leave Geneva every last one of you,
Saturn will be converted from gold to iron,
RAYPOZ will exterminate all who oppose him,
Before the coming the sky will show signs.

 

[malawi_glenn]

And, by the way, I would like to suggest that if cosmic rays hitting atoms in the Earth's atmosphere are producing black holes, these holes will pass just once through the planet, and then disappear into the great unknown. Their velocity would be way beyond escape velocity.

So what have escape velocity antyhin to do with it? What matters is the directon they go and how they interact with material. Consider for example neutrinos from the sun which passes through the eart 10000000000 each second and square metre. What matters here is the interaction crossection, not the escape velocity...

 

[Almanzo]

The escape velocity seems relevant to me, because a black hole escaping from Earth (and, preferably, from the Solar System too) seems less immediately threatening than a black hole following a decaying orbit inside Earth and finally coming to rest in the center.

 

[malawi_glenn]

The escape velocity seems relevant to me, because a black hole escaping from Earth (and, preferably, from the Solar System too) seems less immediately threatening than a black hole following a decaying orbit inside Earth and finally coming to rest in the center.

Yes, if BH initial velocity is directed radial outwards, then it is a good argument. But since the vast majority of HighE-cosmic rays are directed radial inwards to earth, most of MBH's will go towards earth.. *scary* :-)

 

[Almanzo]

EDIT: ah, I think I see your argument now: you seem to think that if a BH crosses a nucleus, it "must" absorb it, no matter how small the hole. But on the BH's scale, the nucleus is not a "massive filled thing", in the same way as for a fast electron, the atom is not a massive filled thing".

What you estimated was roughly the probability of a NEUTRON to interact in matter.

You have a point. Just like the atom is made up of a nucleus and some electrons within a lot of empty space, so the nucleus is made up of protons and neutrons, which are themselves made up of up and down quarks. My expectation is that the hole would have to actually hit one of the most fundamental particles to achieve anything. Its gravity, at this stage, is much to weak to draw a particle in against the electromagnetic or the nuclear force.

However, what is the size of the most fundamental particle? If an electron is fundamental, one might try to calculate a minimum size for an electron, based on the idea that its total mass must be larger (or, at any rate, not smaller) than the mass of its electric field. This gives me a diameter of roughly 1/100.000 of the atom diameter for the electron. The quarks, being more massive, and carrying less charge, might be smaller, say 1/10.000.000 of the atom diameter. Or they might not be that small; they carry other fields, which presumably have their own contributions to their mass.

The black hole would be much smaller still; essentially point sized relative to the quarks and electrons.

Would swallowing an electron cause the hole to attract and devour the nucleus (and the other electrons after that)? Perhaps not. If it formed by cosmic radiation in the atmosphere, it will have relativistic speed, and may not dwell long enough in the vicinity of the other particles to draw them in. But if it formed in the LHC, at a moderate speed, if might well have enough time to do so. And otherwise it would be attracted to any nucleus it passed, increasing its effective cross section until it had neutralized its charge.

At any rate, I wonder whether a black hole could get away after swallowing just one quark. Not only would it have a partial charge, it would also have a colour charge, and be strongly attracted to the remaining quarks. I would at least expect it to take the other two quarks of the same nucleon. If this nucleon is a neutron, this might have little effect. If a proton, the hole would again have charge, and attract electrons. Eventually it would catch one, whether from the same atom or from somewhere else. It would be the electrons that moved towards it, rather than vice versa, considering that the hole is initially 10.000 times as massive at as a proton, and twenty million times as massive as an electron.

But, yes, the cross section of 1/100,000 squared might be wrong. Suppose that it is essential for the hole to hit a quark, with a cross section of 1/100,000,000 squared, and suppose that even if it does so, it only takes one nucleon mass, not an entire atom. Instead of having to pass through ten billion layers of atoms, it would have to pass through ten million billion layers of atoms, or one hundred kilometers of solid mass. On one passage through the Earth the hole would acquire roughly 100 proton masses; it would need 100 orbits to double its mass, which it would complete in a week. The growth would not be linear, because the diameter of the hole itself would slowly increase, but it might be centuries before this became noticable.

However, there would be more than one hole. The holes would be in decaying orbits, ending up in a small region, where they would eventually meet. The diameter of a black hole is proportional to its mass, not to the cube root of its mass. So the ability of a combination of holes to increase its mass would become proportional to the square of the total mass. And when the mass reaches 10³⁰ proton masses, or a few kilograms, their gravity becomes strong enough to overcome interatomic (van der Waals) forces and draw neighbouring atoms in. From there, the growth is exponential.

I expected the "dormant" stage to last a few decades, but it may actually be a hundred thousand years.

 

[mal4mac]

I'm sorry, but Martin Rees does not qualify as someone concerned about its safety...he has enthusiastically articulated his position of support.

You can be concerned about safety, but still enthusiastically support something. For instance, a sky diver might be very safety conscious but still jump.

 

[mal4mac]

Well we can always hope that people are reading the saftey reports and that we save a few. Guys who already from the beginning don't know a thing about neither physics nor how to read reports...

 

[ZapperZ]

You can be concerned about safety, but still enthusiastically support something. For instance, a sky diver might be very safety conscious but still jump.

.. which means that he HAS checked that everything is safe enough to continue to jump. If it isn't, he won't have jumped!

So if you think your analogy is correct, Martin Rees has checked that the LHC is safe and thus, will support its running. Then why are you still using his "concern" here? Via your analogy, it is SAFE. Case closed!

Zz.

 

[vanesch]

You have a point. Just like the atom is made up of a nucleus and some electrons within a lot of empty space, so the nucleus is made up of protons and neutrons, which are themselves made up of up and down quarks. My expectation is that the hole would have to actually hit one of the most fundamental particles to achieve anything. Its gravity, at this stage, is much to weak to draw a particle in against the electromagnetic or the nuclear force.

You have to get away from the "drawing in" picture. You rather have an *interaction probability* - which is in a normalized form, the so-called cross section (which, I repeat, is at this level usually not to be taken equal to any geometrical cross section, although this might give you eventually an idea of order of magnitude).

So when a MBH crosses nuclear matter - which it its scale, is a swarm of point-like quarks, gluons or eventually their constituents whatever that may be, and with each of these particles, it has a certain interaction probability, and one of the possible interactions is "eating up" (but also: scattering, or other things). This is very similar to what happens when a high-energy electron crosses a proton, only there's no "eating up" reaction, but only scattering. A high-energy electron kicks out, most of the time, just one quark. This gives then rise to a hadronic jet of the kicked-out quark, and a hadronic jet of the rest of the proton.
If we had something similar with a BH, I can imagine (although this is guesswork on my side), that something similar happens: the BH "eats" a single quark, gets colored, and a "hadronic jet" develops in which a newly created color charge will bind (strong force) to the BH, and the remnant quarks will also generate a jet. The colored BH, bound to another quark, will then maybe end up by eating up that bound quark too after some time (depends on its probability to interact with it). But a priori it will not "draw in" the other quarks of the remnant of the proton.

However, what is the size of the most fundamental particle? If an electron is fundamental, one might try to calculate a minimum size for an electron, based on the idea that its total mass must be larger (or, at any rate, not smaller) than the mass of its electric field. This gives me a diameter of roughly 1/100.000 of the atom diameter for the electron.

For sure not. 1/100 000 of an atom diameter is about the size of a nucleus. We know that electrons are way way smaller, given that we use it as a probe inside the proton. In fact, in the standard model, we consider the electron to be point-like.
But again, you cannot really use geometrical arguments to derive interaction probabilities. There is no "touching" at this scale.

But if it formed in the LHC, at a moderate speed, if might well have enough time to do so. And otherwise it would be attracted to any nucleus it passed, increasing its effective cross section until it had neutralized its charge.

You have to understand that far most interactions at the LHC are also not in the center of gravity of the two protons, but rather in the center of gravity of the two interacting quarks, which have wildly different momenta.

At any rate, I wonder whether a black hole could get away after swallowing just one quark. Not only would it have a partial charge, it would also have a colour charge, and be strongly attracted to the remaining quarks.

My guess is that it would end up in a bound state (under the strong force) with a complementary quark.

But, yes, the cross section of 1/100,000 squared might be wrong. Suppose that it is essential for the hole to hit a quark, with a cross section of 1/100,000,000 squared, and suppose that even if it does so, it only takes one nucleon mass, not an entire atom. Instead of having to pass through ten billion layers of atoms, it would have to pass through ten million billion layers of atoms, or one hundred kilometers of solid mass. On one passage through the Earth the hole would acquire roughly 100 proton masses; it would need 100 orbits to double its mass, which it would complete in a week. The growth would not be linear, because the diameter of the hole itself would slowly increase, but it might be centuries before this became noticable.

As I said somewhere else jokingly, we might already have produced a lot of such black holes at the Tevatron, which are just starting to eat out the Earth from inside.

 

[mal4mac]

.. which means that he HAS checked that everything is safe enough to continue to jump. If it isn't, he won't have jumped!

So if you think your analogy is correct, Martin Rees has checked that the LHC is safe and thus, will support its running. Then why are you still using his "concern" here? Via your analogy, it is SAFE. Case closed!

Zz.

Martin Rees might still jump, given his safety analysis, but others might decide, on the same analysis, that it is too risky for them. So the case is never closed, because people will always have different subjective preferences.

 

[Almanzo]

If we had something similar with a BH, I can imagine (although this is guesswork on my side), that something similar happens: the BH "eats" a single quark, gets colored, and a "hadronic jet" develops in which a newly created color charge will bind (strong force) to the BH, and the remnant quarks will also generate a jet. The colored BH, bound to another quark, will then maybe end up by eating up that bound quark too after some time (depends on its probability to interact with it). But a priori it will not "draw in" the other quarks of the remnant of the proton.

Would it be fair to say that after "eating" a quark, a micro black hole would behave like a quark, although an unusually massive one? In that case, micro black holes, formed by cosmic radiation or whatever, might be found inside some "protons" and account for some of the Dark Matter. That would be interesting, because such "heavy protons" might be harvested from space, and manipulated by means of chemistry. Superdense materials might be created.

Once confined inside an elementary particle, the micro black hole would probably be harmless. (Unless too many of them existed within a small space, and the treshold for formation of a black hole would be exceeded once more. But on second thought, an atom containing a 10.000 proton mass black hole would have merely 10.000 times the density of normal matter, while neutronium has 10¹⁵ times that density. If neutron stars can be kilometer-sized, confined micro black holes would not quickly become dangerous.)

For sure not. 1/100 000 of an atom diameter is about the size of a nucleus. We know that electrons are way way smaller, given that we use it as a probe inside the proton. In fact, in the standard model, we consider the electron to be point-like.
But again, you cannot really use geometrical arguments to derive interaction probabilities. There is no "touching" at this scale.

That is strange. I will try to recalculate the minimum radius for the electron. The idea is that the electric field E = Q/4*pi*epsilon*r² had an energy density U = epsilon*E²/2, and therefore a mass density U/c². Which can be integrated over the space outside the electron to yield a mass proportional to 1/R, where R is the radius of the electron. In using the electron as a probe, would it be the size of the electron (at rest) that matters, or rather the wavelength of the (moving) electron's de Broglie wave?

 

[vanesch]

That is strange. I will try to recalculate the minimum radius for the electron. The idea is that the electric field E = Q/4*pi*epsilon*r² had an energy density U = epsilon*E²/2, and therefore a mass density U/c². Which can be integrated over the space outside the electron to yield a mass proportional to 1/R, where R is the radius of the electron.

If you do that, you will find the "classical electron radius" http://en.wikipedia.org/wiki/Classical_electron_radius or the Thomson scattering length.

But that's not the "size" of the electron as a "bullet".

 

[vanesch]

Once confined inside an elementary particle, the micro black hole would probably be harmless.

Not really, because it would interact sooner or later with its partner and "eat it". Just like positronium (a bound state of a positron and an electron) can sooner or later annihilate.

 

[Sakha]

How much time does it takes to the protons to reach 99.999% of c in the LHC?

 

[gendou2]

Good question. There are several stages in the acceleration of the beams. See this video for some more info:

 

[humanino]

How much time does it takes to the protons to reach 99.999% of c in the LHC?

In which referential frame ?

 

[Sakha]

In the detectors referential frame.

 

[gendou2]

The Schwarzschild radius R_S of an (4+n)-dimensional black hole:
R_s = \frac{1}{\sqrt{\pi} M_p} \left[ \frac{M_{BH}}{M_p} \left( \frac{8 \Gamma\left( \frac{n+3}{2} \right)}{n+2} \right) \right] ^{\frac{1}{n+1}}
How do I transform this equation into Systeme International units?

First of all, let's stick to 4 dimensions for simplicity where:

R_s = \frac{2Gm}{c^2}

Solving for the smallest black hole having 1 Planck mass:

R_s = 3.23123546 * 10^-35 meters

References:
http://en.wikipedia.org/wiki/Schwarzschild_radius
http://en.wikipedia.org/wiki/Planck_mass

 

[humanino]

In the detectors referential frame.

I thought we had the convention that smileys indicate a joke

R_s = 3.23123546 * 10^-35 meters

Can we use this to set up an upper bound on the cross section for MBH matter accretion ?

 

[gendou2]

Sure, but I'm not sure how to do that.
Using the same math as my other post, I calculate the evaporation time of a black hole this size to be 1.38 * 10^-40 seconds.
This small size and evaporation time suggests to me that the energy density required for accretion of such a black hole is unimaginably enormous.
In other words, I subscribe to the general statement that present day micro black holes are unstable. Period.