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Black hole in LHC?

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chinatruth
#127
Sep6-08, 11:08 AM
P: 13
Quote Quote by jms5631 View Post
In short, no. I don't understand the rationale, particles won't be accelerated to the speed of the light under any circumstance in the LHC. Very close to it, but not quite there. Particles collide at far less than the speed of light in other colliders, and everyday in the upper atmosphere and we are still here. I don't know if your teacher was joking or if you just misunderstood him, but I can't tell you where he's coming from here.

Thanks!! I am just a freshman(not physics major).The controversies on LHC have disturbed me a lot for so many days. I feel much better now.
jms5631
#128
Sep6-08, 02:27 PM
P: 55
I understand, there are a ton of misrepresentations and media sensationalism out there. As someone without a significant science background, you are in a position of vulnerability to these misunderstandings and manipulation of the fundamentals, like the majority of the people out there. Just know that the aim of science is to uncover objective truths about the world to deepen our understanding; surely that would diffcult to accomplish if it were oblitierated. Scientists have a very solid thoeretical and observational grasp of the physics involved in high energy collisions such as these. We see higher in the atmosphere on a regular basis. Even if you can't understand the substance of these papers, read the conclusions of the reports to put your mind at ease.

http://arxiv.org/PS_cache/arxiv/pdf/...808.4087v1.pdf
http://arxiv.org/PS_cache/arxiv/pdf/...807.3349v1.pdf
http://arxiv.org/ftp/arxiv/papers/0806/0806.3414.pdf
OAQfirst
#129
Sep6-08, 11:06 PM
P: 65
Quote Quote by mal4mac View Post
Dr Adrian Kent, a seriously qualified quantum theorist of DAMPT at Cambridge, has worries:

"What's an Acceptable Risk for Destroying the Earth?

From time to time, people have raised the worry that a particular physics experiment just might destroy the Earth. The first time this was seriously considered seems to have been before the first A-bomb and H-bomb tests. More recently, the possibility was raised that, if unknown physics included some particularly unfortunate features, the RHIC experiments at Brookhaven, or the forthcoming ALICE collider experiments at CERN, could have disastrous consequences. When physicists address these worries at all, they've tended to argue that (a) something would have to be very wrong with our understanding of physics for the risk to be present at all, (b) even if it is, we can show on empirical grounds that any risk must be so small that the possibility just isn't worth worrying about. Which rather begs the question, of course: how small *is* an acceptable risk? On this point, the various analyses seem to have been extraordinarily cavalier. At various times physicists have argued for going ahead with experiments without further ado on the basis of risk bounds ranging from 1 in 5000 (!) (the first Brookhaven analysis of the RHIC experiments) through 1 in 300,000 (Compton's estimate of the probability of igniting the Earth's atmosphere in the first A-bomb test) to 1 in 50,000,000 (the CERN analysis of the RHIC experiments). It seems to me that a little thought suggests all these risk bounds are far, far too large for comfort."
From page two of "A critical look at risk assessments for global catastrophes" by Adrian Kent http://arxiv.org/PS_cache/hep-ph/pdf/0009/0009204v6.pdf:
II. HISTORICAL EXAMPLES
The first catastrophe mechanism seriously considered seems to have been the possibility, raised in the 1940s at Los Alamos before the first atomic bomb tests, that fission or fusion bombs might ignite the atmosphere or oceans in an unstoppable chain reaction. Investigation led to an analysis by Konopinski et al. [3] which fairly definitively refuted the possibility. Compton was later reported, in a published interview [4] with Pearl Buck, as saying that he had decided not to proceed with the bomb tests if it were proved that the chances of global catastrophe were greater than three in a million, but that in the event calculation proved the figures slightly less.
Quote Quote by kressworks.com
A black hole ate my planet

...

Yet in November 1975, The Bulletin of the Atomic Scientists claimed that Arthur Compton, a leading member of the Manhattan Project, had said that there really was a risk of igniting the atmosphere. It turned out to be a case of Chinese whispers: Compton had mentioned the calculation during an interview with the American writer Pearl Buck, who had got the wrong end of the stick.
http://www.kressworks.com/Science/A_..._my_planet.htm

Ahem. But of course, this is according to Kressworks (NewScientist). For what that's worth, I dunno.
vanesch
#130
Sep7-08, 12:26 AM
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Quote Quote by OAQfirst View Post
From page two of "A critical look at risk assessments for global catastrophes" by Adrian Kent http://arxiv.org/PS_cache/hep-ph/pdf/0009/0009204v6.pdf:

... At various times physicists have argued for going ahead with experiments without further ado on the basis of risk bounds ranging from 1 in 5000 (!) (the first Brookhaven analysis of the RHIC experiments) through 1 in 300,000 (Compton's estimate of the probability of igniting the Earth's atmosphere in the first A-bomb test) to 1 in 50,000,000 (the CERN analysis of the RHIC experiments). It seems to me that a little thought suggests all these risk bounds are far, far too large for comfort." ....
I'm a genius !
chinatruth
#131
Sep7-08, 05:21 AM
P: 13
Here are two questions, thanks


Question.1.
I've read about the introduction about LHC and I know that the temperature produced in LHC would be 10,000 times higher than the center of the sun.
As the temperature is so high, what materials are used in LHC to prevent from being burned into ashes....?????????
Is there any possibility that such a scaring temperature causes a disaster????

Question.2.
If the LHC produces millions of black holes, would these mini black holes combine to a larger one which does not evaporate and has the ability to suck things in??


What's wrong with my thoughts above?? Please point it out to me ..Thanks!
tiny-tim
#132
Sep7-08, 05:47 AM
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Quote Quote by chinatruth View Post
If the LHC produces millions of black holes, would these mini black holes combine to a larger one which does not evaporate and has the ability to suck things in??
Hi chinatruth!

A black hole has no sucky-power

a black hole has exactly the same gravitational attraction as any star of the same mass.

It doesn't vacuum-up the things around it

it's like one of those sea-creatures that just sits there open-mouthed and hopes other things swim into it.

Anything that goes past a black hole, however close, carries on past it, just like a comet "grazing" the sun.

Black holes in space only get larger because of collisions between other bodies, accidentally sending one of them in just the right direction.

And anything that accidentally falls into a black hole would have crashed into a star of the same mass in the same position long before.

If the sun or the moon were replaced by a black hole of the same mass, we wouldn't notice any difference (well, except for it being darker ).

An uncharged mini-black hole would find it very difficult to hit anything!

Even a charged mini-black hole would probably just go into "orbit" round an ordinary particle (like an electron "orbiting" a nucleus) and if it did manage to swallow anything of the opposite charge, it would become uncharged.
chinatruth
#133
Sep7-08, 07:43 AM
P: 13
Quote Quote by tiny-tim View Post
Hi chinatruth!

A black hole has no sucky-power

a black hole has exactly the same gravitational attraction as any star of the same mass.

It doesn't vacuum-up the things around it

it's like one of those sea-creatures that just sits there open-mouthed and hopes other things swim into it.

Anything that goes past a black hole, however close, carries on past it, just like a comet "grazing" the sun.

Black holes in space only get larger because of collisions between other bodies, accidentally sending one of them in just the right direction.

And anything that accidentally falls into a black hole would have crashed into a star of the same mass in the same position long before.

If the sun or the moon were replaced by a black hole of the same mass, we wouldn't notice any difference (well, except for it being darker ).

An uncharged mini-black hole would find it very difficult to hit anything!

Even a charged mini-black hole would probably just go into "orbit" round an ordinary particle (like an electron "orbiting" a nucleus) and if it did manage to swallow anything of the opposite charge, it would become uncharged.


Thank you very much for giving me such a specific answer!!!!!!
What about the first question?? About the temperature??
Vanadium 50
#134
Sep7-08, 08:43 AM
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There is a difference between heat and temperature. You can stick your hand in an oven at 200C for a few seconds with no ill effect. If you tried that in a pot of boiling water at 100C, you would be very badly burned.
Vanadium 50
#135
Sep7-08, 10:07 AM
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Quote Quote by mal4mac View Post
At various times physicists have argued for going ahead with experiments without further ado on the basis of risk bounds ranging from 1 in 5000 (!) (the first Brookhaven analysis of the RHIC experiments)...
Kent is being more than a little disingenuous here. The 5000 number is actually 10000, it was in an other-than-final version of the paper, and most seriously, it is not what he claims it is. It's an intermediate step, and Busza et al. use this to explain why they prefer to use the astrophysical limits of Dar et al. instead of the astrophysical limits set by the moon surviving five billion years.

Personally, I think the standard Kent sets for risk ([tex]10^{-22}[/tex]) is absurd. Consider the risk that if we open a bottle, an angry genie will emerge from it and wipe out all life on earth. Since we've made maybe a trillion bottles to date, and this hasn't happened yet, we only know that the risk is less than around ([tex]10^{-12}[/tex]), a full ten billion times larger than Kent would permit. According to his argument, we should ban bottles.

Quote Quote by mal4mac View Post
It reports that CERNs top theorists are suggesting we shouldn't worry. I'd be much happier if Moscow and CalTech had produced such a comment. Aren't CERN theorists just slightly :-) interested parties? There's a one in many millions chance of Dr CERN-Theorist being exterminated if CERN goes online, but zero chance of them getting a Nobel if it doesn't! So the odds look great to them...
Once you've decided that physicists are murderous liars, willing to slaughter everyone on the planet (including their friends and families) in pursuit of a Nobel prize, there's really nothing left to say. Just out of curiosity, do you have any evidence for your claim?
chinatruth
#136
Sep7-08, 10:36 AM
P: 13
Then what are the differences between cosmic rays and the experiment in LHC??

CERN compared cosmic rays with LHC and got the conclusion that LHC would not produce any black holes because our earth or other planets have been being bombarded by cosmic rays for billions of years but we are still safe.

From this logic, I can also get a prediction that we cannot find any "Higgs boson" because we didnot find that in any cosmic rays observed.(absolutely this is wrong)
I mean, the comparison between LHC and cosmic rays cannot hold water with me,


I want to know what's wrong with my thought.
cristo
#137
Sep7-08, 10:48 AM
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Quote Quote by chinatruth View Post
From this logic, I can also get a prediction that we cannot find any "Higgs boson" because we didnot find that in any cosmic rays observed.(absolutely this is wrong)
Cosmic rays are high energy particles from outer space that approach the earth, enter the atmosphere and scatter off particles in the atmosphere, resulting in showers of particles that fall to earth. The LHC is a setup in which two beams of protons are made to collide, and all the products are analysed such that all the energy of the system is conserved, and thus we can tell which particles are present. Such a thing is incredibly difficult to observe and tell what has happened, even when you've got a multi million pounds detector surrounding the event and calculating the energy given off by every single subatomic particle produced. It is impossible to perform such a calculation for cosmic rays.

The point is, though, that were black holes going to be produced at the energies of the LHC, then they would have been produced by cosmic rays. However, we're still here!
tiny-tim
#138
Sep7-08, 11:49 AM
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Hi chinatruth!
Quote Quote by chinatruth View Post
What about the first question?? About the temperature??
I dunno!
Quote Quote by chinatruth View Post
Then what are the differences between cosmic rays and the experiment in LHC??

CERN compared cosmic rays with LHC and got the conclusion that LHC would not produce any black holes because our earth or other planets have been being bombarded by cosmic rays for billions of years but we are still safe.

From this logic, I can also get a prediction that we cannot find any "Higgs boson" because we didnot find that in any cosmic rays observed.(absolutely this is wrong)
As cristo says, if the LHC produces Higgs bosons, then the cosmic rays will already have been producing them but with no way for us to detect them.

Making particles go fast is easy . Detecting particles is difficult .
Remember, most of the expertise and expense in the LHC was not in building the accelerators, but in building the detectors!
lightarrow
#139
Sep7-08, 01:13 PM
P: 1,521
Quote Quote by chinatruth View Post
Question.1.
I've read about the introduction about LHC and I know that the temperature produced in LHC would be 10,000 times higher than the center of the sun.
As the temperature is so high, what materials are used in LHC to prevent from being burned into ashes....?????????
Is there any possibility that such a scaring temperature causes a disaster????
That temperature is produced in the void, at the centre of the "pipe", far from the container, and in a very small region of space, and for a very tiny fraction of second. Imagine a normal lamp: the tungsten filament reach more than 3000 C, but the glass bulb doesn't melt.
aquitaine
#140
Sep7-08, 09:18 PM
P: 200
Quote Quote by chinatruth View Post
well um our science teacher told us that in LHC if the atoms didn't collide at the speed of light on wednesday, that the world will become a huge black hole and suck us in!!!!!!!!!!!!!!!


Is this true!????This scared the whole class!!

Help me by analysing this ~~!Thanks ~!~
On another note CERN is getting flooded with phone calls from panicky people either pleading to shut the machine down or giving them death threats.
vanesch
#141
Sep8-08, 03:41 AM
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Quote Quote by Vanadium 50 View Post
Personally, I think the standard Kent sets for risk ([tex]10^{-22}[/tex]) is absurd. Consider the risk that if we open a bottle, an angry genie will emerge from it and wipe out all life on earth. Since we've made maybe a trillion bottles to date, and this hasn't happened yet, we only know that the risk is less than around ([tex]10^{-12}[/tex]), a full ten billion times larger than Kent would permit. According to his argument, we should ban bottles.
I think this is an important point to make indeed. There are two kinds of risks associated with "doing new things". One risk is the objective probability that it will go wrong and do something evil, like eat up the earth. If the objective probability of such an event is stated to be p (say, 1 in 1 000 000 for instance) that means that if we were to repeat this experiment on, say, 100 million earth-like planets, that 100 of them on average would be eaten up/blown up whatever it was, and that 99 999 900 of them would be ok.

The other risk is the subjective risk (Bayesian "belief" risk) of weird things happening. This is not a probability in the frequentist sense, but a belief or not in the existence of a specific phenomenon, like evil genies popping out of bottles. Although certain theorists might feel insulted, posing the hypothesis of making tiny black holes at LHC energies which would not undergo Hawking radiation are, to me, not very far from genies popping out of a bottle. What "risk" is associated with such hypothetical phenomena ? If the phenomenon doesn't exist - that means, if it was just a quirk in the mind of a theorist or a story teller - then you can repeat the experiment on a gazillion earth-like planets, it will NEVER happen. If on the other hand, the phenomenon exists, it can occur at ANY rate, even "for sure". What do we do then ? It cannot be excluded that totally unexpected and weird things happen, and if we really do something totally new for the very first time in the universe, it is totally impossible to know. We might offend a deity which collapses the entire universe just by uttering a new phrase, we might get a genie out of a bottle, we might invoke the "coming of the great white handkerchief", or we might turn the earth in a black hole.
Happily, most things (except for uttering phrases) we can do happen already somewhere in the universe, so by analyzing these things, we can sometimes obtain upper limits for the probability of the phenomenon happening under the hypothesis that the phenomenon is possible in the first place. But note that these estimates are not estimates of the probability that this will happen: they are conservative upper bounds.

Of course, from a decision PoV, Bayesian "ignorance" probability is probably to be treated on the same level as "genuine frequentist probability".
The danger of fixing too low probability levels for weird things to happen, is that we will for ever be stiffled in attempting new things - even at first totally inoffensive things, like writing phrases (which might invoke magical powers).
chinatruth
#142
Sep8-08, 08:33 AM
P: 13
Quote Quote by vanesch View Post
I think this is an important point to make indeed. There are two kinds of risks associated with "doing new things". One risk is the objective probability that it will go wrong and do something evil, like eat up the earth. If the objective probability of such an event is stated to be p (say, 1 in 1 000 000 for instance) that means that if we were to repeat this experiment on, say, 100 million earth-like planets, that 100 of them on average would be eaten up/blown up whatever it was, and that 99 999 900 of them would be ok.

The other risk is the subjective risk (Bayesian "belief" risk) of weird things happening. This is not a probability in the frequentist sense, but a belief or not in the existence of a specific phenomenon, like evil genies popping out of bottles. Although certain theorists might feel insulted, posing the hypothesis of making tiny black holes at LHC energies which would not undergo Hawking radiation are, to me, not very far from genies popping out of a bottle. What "risk" is associated with such hypothetical phenomena ? If the phenomenon doesn't exist - that means, if it was just a quirk in the mind of a theorist or a story teller - then you can repeat the experiment on a gazillion earth-like planets, it will NEVER happen. If on the other hand, the phenomenon exists, it can occur at ANY rate, even "for sure". What do we do then ? It cannot be excluded that totally unexpected and weird things happen, and if we really do something totally new for the very first time in the universe, it is totally impossible to know. We might offend a deity which collapses the entire universe just by uttering a new phrase, we might get a genie out of a bottle, we might invoke the "coming of the great white handkerchief", or we might turn the earth in a black hole.
Happily, most things (except for uttering phrases) we can do happen already somewhere in the universe, so by analyzing these things, we can sometimes obtain upper limits for the probability of the phenomenon happening under the hypothesis that the phenomenon is possible in the first place. But note that these estimates are not estimates of the probability that this will happen: they are conservative upper bounds.

Of course, from a decision PoV, Bayesian "ignorance" probability is probably to be treated on the same level as "genuine frequentist probability".
The danger of fixing too low probability levels for weird things to happen, is that we will for ever be stiffled in attempting new things - even at first totally inoffensive things, like writing phrases (which might invoke magical powers).


you mean, the LHC experiment is an objective risk??????
Vanadium 50
#143
Sep8-08, 09:28 AM
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Quote Quote by vanesch View Post
Of course, from a decision PoV, Bayesian "ignorance" probability is probably to be treated on the same level as "genuine frequentist probability".
The danger of fixing too low probability levels for weird things to happen, is that we will for ever be stiffled in attempting new things - even at first totally inoffensive things, like writing phrases (which might invoke magical powers).
The problem with making decisions this way is how do you make an objective comparison about the risks of opening the bottle and releasing an angry genie versus not opening the bottle and risking the wrath of the god of bottle-opening? According to this line of reasoning, neither of the two mutually exclusive actions has acceptable risks.
vanesch
#144
Sep8-08, 09:53 AM
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Quote Quote by chinatruth View Post
you mean, the LHC experiment is an objective risk??????
No. It is rather a subjective risk: we will do "new" things, and an exotic phenomenon which might have an evil effect can hence, by ignorance, not be excluded (just as vanadium's genie from the bottle). If we were really doing something unique in the LHC, then there would be no way to tell whether or not this might actually happen, and anybody's guess would be as good as any other.

However, what is going to happen at the LHC is not unique in the universe. From that given, we can try to derive an upper limit to the eventual objective probability of some evil effect, under the hypothesis that it even exists. THESE are the numbers you find scattered around. They are *upper bounds* for an unknown objective probability, which might very well actually be 0 (said phenomenon doesn't exist).

Vanadium gave the perfect example: it is not unconceivable that there is a low objective probability that an evil genie that will destroy the earth pops out of a bottle when we open it. But from the fact that we already opened 10^12 bottles, and that this didn't happen, we can deduce that IF ever such evil genies exist, the probability for them to pop out of a bottle cannot be larger than about 10^-12. That doesn't mean at all that we estimated the probability of evil genies to exist to be about equal to 10^-12 - honestly I don't believe they exist at all. But I have no scientific way to prove to you that this won't happen, and hence the best I can do is to say that opening a new bottle will represent a probability smaller than 10^-12 to destroy the earth. If you require (as Kent does) insanely low risk levels, well, then 10^-12 is not good enough, and hence from now on it is prohibited to open any bottle. Do you realise the burden such requirement for extremely low risk levels entails ?

Now, opening bottles is a very common activity, and that's what allowed us in the first place to give the upper bound of 10^-12. But imagine that we said the same for, say, landing on the moon. Imagine that somebody fears that we might wake up a monster hidden in the moon, which will eat the earth. As we haven't done many moon landings, this time we don't have a 10^12 trials at our disposal. Only a few tens or at most hundred (if you include robotic landings and such). So "landing on the moon could have a 1% chance of destroying the earth!". Nobody made the argument, so we didn't worry. In the 60ies, there weren't many moonlandings and then "landing on the moon could have a 30% chance of destroying the earth". We didn't know. We took a huge risk waking up the monster in the moon. Turns out there wasn't such a monster... or actually, we still don't know - there's still a 1% upper bound on the risk of waking up the monster if ever we do a new moon landing. Should we risk the earth ?

The thing with the LHC is similar. Normally, the LHC won't make black holes. It is only in very contrived theoretical speculations that spacetime is warped in such a way that the low LHC energies could do so, and even in that case, if they respect the second law of thermodynamics, they should evaporate immediately. This kind of theorist's invention is IMO not very far from evil genies, as it is based on not much more than a whole load of speculation.
But we don't know for sure, as this is new. So one looks at the number of natural collisions at LHC energies that would have had the potential to do so and tries to estimate an upper bound of the probability that an evil thing could have happened (from the fact that it didn't). This gives us then an upper bound of having anything seriously evil in the LHC. If no collisions ever happened in nature at LHC energies, we would not be able to find such an upper bound. We would be left with an upper bound of "100% chance that we destroy the earth".


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