Black Holes at the LHC - again
I am presently writing on a post on 'The Illusion of Knowledge', and I can't but find it ironic that while doing so I am distracted by those suffering from it. Peter Steinberg over from Entropy Bound (is this a black hole hanging on his blog, or do I start having halluzinations?) sent me a link to an overexposed YouTube video "The LHC-- the end of the world again?" showing a teenage girl in a garden babbling about how the LHC will cause the end of the world. Starting with the disclaimer "I don't have a very technical brain," the main statement is "So, we're creating a very unnatural situation."
Unnatural situation, my ass. When I was that age I was worried about soil erosion, overfishing, acid rain, desertification, the greenhouse effect, global political instabilities, deforestation, air- and water pollution, population growth, nuclear waste, overuse of fertilizers and pesticides, and a dozen other 'unnatural situations' that are still problems today (and that I'm still worried about). So here's my message to the YouTube generation: if you have too much time on your hand, and have already re-applied make-up three times today, why don't you talk about these infinitely more pressing problems? Because somebody could expect you do something about it?
And how 'natural' do you think YouTube is to begin with, maybe we better shut it down - I am sometimes very sure it will cause the end of the world as we know it.
Following some further links, I eventually came via another video titled "Did Nostradamus predict the LHC will create a Black Hole?" to a site called revelation13.net where you can read the following nonsense
"But perhaps creation of a black hole is a holographic parallel to the world reaching 6.66 billion population in 2008, and the rise to power of the Antichrist in Russia. If a black hole is created by LHC, then initially it might not be noticed, but it could gravitate to the center of earth and start swallowing the earth's core, perhaps over years. Perhaps such an event could be the cause of the Mayan calendar prophesy of the December 2012 destruction of earth. Lets hope for the best in this situation. If that should happen then nothing could be done about it. I think it is an interesting coincidence that CERN is turned on as the world population reaches 6.66 billion (in April 2008), 666 being the number of the Antichrist, and as the possible Antichrist Putin reached 666 months age in April 2008. Note that 666 is the number of the Antichrist in Revelation 13, the Antichrist or Beast being a Satanic imitation of Christ. In Greek, the original language of the Bible's New Testament, each letter is also a number, and therefore a word can be connected to a number by adding the letter-numbers."
And another great find is this: Black hole eating the earth, artist's impression
And what am I doing while the end of the world is coming close and the antichrist is apparently on his way? (Or is it 'her way'? Does the antichrist have a penis? Anybody knows?) Well, what I was doing today, besides wondering whether the antichrist has a penis, is preparing a colloq I'm supposed to give next week about, guess what, black holes at the LHC. (Look at this, they've even put together a poster, isn't that nice?) Too bad I can't download the above video, I'd have loved to embed it, it is just hilarious.
So, here is again all the reasons why the LHC isn't going to create a black hole that will cause the end of the world:
- To begin with, please notice that the creation of a black hole at the LHC is *not* possible in the standard framework of Einstein's theory of General Relativity. To produce black holes at the energies LHC can reach, it needs a modification of General Relativity at small distances. This could potentially be the case if our world had large extra dimension. There is however no, absolutely no, evidence so far this is really the case. The scenario is pure speculation, a hypothesis, a theory, or call it wishful thinking [1].
- It is not only that there must be compactified extra-dimensions, but the parameters of that model (their size and number) have to be in the right range. We know that the case with one dimension is excluded, and two should also already have shown up in sub-mm measurements, so this case too is strongly disfavoured. There are further various constraints from astrophysics that put strong bounds on the cases with three and four. But most importantly, there is no good reason known why these extra-dimensions should have the radius they need to have so quantum gravity is observable at the LHC - no reason other than it would be nice to have it shown up at these energy scales.
- Now to come to the issue of the black holes should they be created. Hawking showed in '75 using quantum field theory in the curved spacetime caused by a collapsing matter distribution that black holes emit thermal radiation. The temperature of this radiation is inverse to the radius of the black hole. The black holes that would be produced at the LHC would be extremely tiny, ~ 10-18 meters, and thus be extremely hot ~ 1016 K (that's a 1 followed by 16 zeros). They would decay within a time scale of roughly 1 fm/c, that is 10-23 seconds. They would not even reach the detector, instead they would decay already in the collision region. The only thing that could be measured are the decay products.
- The temperature of these black holes is so hot, they can not grow even if they pass through matter of very high density, like e.g. a gluon plasma or a neutron star. The mass gain from particles coming in the black hole's way (which depends on the density) is far smaller than the mass loss from the evaporation. The density of the earth is further several orders of magnitude smaller than that of nuclear matter, so there is no way the black hole could grow. Even if you assume the black hole has a high γ-factor (and thus experiences a higher density), this is not sufficient to enable it to grow.
- Hawking radiation is *not* a quantum gravitational effect. Hawking's calculation uses two very well known ingredients that are classical General Relativity and quantum field theory. It is true that we do not know quantum gravity, but quantum gravitational effects would only become important in the very late stages of the decay, when the black hole comes into the quantum gravitational regime. This would then affect the observables (and this ambiguity is thus somewhat of an annoyance), but it does not mean the black hole could grow. The reason is that if the black hole grew, it would come into the regime where Hawking's calculation applies to very good approximation, and it would lose mass as predicted. The scale for quantum gravitational effects to be important is the curvature at the horizon, which falls with M/R3 when the black hole grows, where M is the mass of the black hole and R is its radius (which again is a function of the mass).
As to the claim that there are 'people' who doubt black holes radiate, let me first reduce 'people' to 'physicists' since there are apparently also 'people' who doubt that the earth is more then 20,000 years old, or is a sphere (at least to very good accuracy). I know exactly no physicist who doubts that black holes radiate. The one work that I know of has sometimes been referred to is that by Adam Helfer. However, even he states in his paper (gr-qc/0503053) explicitly: "[These results] do not, as emphasized above, mean that black holes do not radiate [...]" [2]. - As has been said many times before, the earth is constantly hit by cosmic rays which undergo in interactions with particles in the earth's atmosphere collisions with a higher center-of-mass energy than the LHC will reach. If it was possible to produce a black hole this way which would then swallow the earth, this would not only very likely already have happened some billion years ago, but we should also see stars disappearing more often, especially neutron stars because of their high density. There is no evidence for that.
- It has then further been argued that the black holes at the LHC would be created in a different center of mass system, and thus not have the same average velocity with respect to the earth. This is correct but there are two points to be said here.
For one, the protons at the LHC will be accelerated to 99.9999991% of the speed of light, which is really fast. I mean, really. If you bang them together it is extremely unlikely the created particles will be in rest or even slow moving relative to the earth. Indeed, as Stefan has explained very nicely previously, their velocity will typically be far higher than the escape velocity of the earth. Pictorially speaking, consider a car crash. Things usually fly around quite a lot, already at 0.0000001% of the speed of light.
Second, even for the few black holes for which that wouldn't be the case, again, they would decay even before they hit the detector. In any case they would definitely not collect in the middle of the earth (or 'gravitate to the center of the earth' or whatever). This is a totally absurd idea that I have however come across several times. It is absurd because the center of the earth would generally not be on the produced object's trajectory (having an initial velocity), and even if it was they wouldn't stop in the center of the earth, why should they? Ever heard of energy conservation? As said previously, they are far to small (cross-section to small) to interact noticeably with the earth's matter so they wouldn't slow down. (If one really pushes it one can now go and estimate how long it would take them to slow down until they get stuck and so on. But frankly, this scenario is already so absurd that such a speculation is totally moot, and an utter waste of time, mine and yours.) - About the claim that the LHC's risk report is biased because it has not been performed by people at "arm's length". Yes, to get a reasonable report about the difficulties the LHC might be facing I would think you ask experts. These experts are usually people working in the field. Would you prefer them to be random sampled from a phone-book? I honestly do not understand why anybody would think people working in theoretical physics have a larger interest in destroying the planet than other human beings.
To be somewhat cynical here, you'd instead think that a lot of theoretical physicists should be really nervous about the LHC because it will test their theories. And no matter what, very many of these theories will be outruled, dead, speculations no longer viable. One of these theories that can be tested is the one with large extra-dimensions. And if it isn't found hundreds of people who have worked on it must face that they have wasted their time, their publications do not describe nature, and the topic is no longer something you can use for a grant proposal. - Finally, let me say that there is always some amount of uncertainty in everything we do. Yes, there is the possibility we are all wrong. There is also the possibility that you wake up tomorrow morning an have turned into a monstrous bug, because a cosmic ray has modified some virus to being capable altering your DNA. Or, as Arkani-Hamed put it so aptly in the recent NYT article: There is some minuscule probability, he said, “the Large Hadron Collider might make dragons that might eat us up.”
I, and I believe many of my colleagues, would really appreciate if the media - TV, print and online - would not support such catastrophe-scenarios and scientifically completely absurd scary stories just because they sell well. There is, in the community, no argument about whether mini-black holes at the LHC are a risk worth worrying about. The answer is simply no, they are not. The story about black holes created in particle colliders that swallow the earth came up first time in '99 regarding RHIC, so it has a long beard in 2008, and it's getting longer every day. If you are running out of topics for the science section, why don't you go and ask some scientists for inspiration?
I have no specific relation the theories investigated here, in fact, not being influenced by subjective preferences is part of what it means to be a scientist (whether we like that or not). I'm not telling you what I wrote here because I want money or publicity for collider physics, or any other reason of personal advantage you could accuse me of. I am telling you that just because black holes at the LHC is not something you should worry about. Worry about some real problems instead.
Further reading (strongly recommended before asking redundant questions):
Note added May 2nd: Clifford from Asymptotia asked me to clarify that with 'quantum gravity' I mean a theory in which gravity is quantized.
[1] And if you don't take into account the presence of large extra dimensions, you will find correctly that there is a factor 1032 missing. Before you suggest this factor has been overlooked in hundreds of peer-reviewed publications, maybe consider redoing your calculation.
[2] It seems to me that even if one bought his approach they would evaporate only faster. It's hard to say though because he states "it is unrealistic at present to expect to be able to make quantitative theoretic predictions".
TAGS: LHC, PHYSICS, BLACK HOLES, NOSTRADAMUS, NONSENSE, PARTICLE PHYSICS
Labels: Particle Physics, Physics, Science and Society
posted by Bee @ 6:25 PM
143 comments
links to this post
143 Comments:
LOL! Okay, but couldn't the LHC destroy the world in lots of other ways, ways that you haven't considered?
What if the high levels of proton speeds causes mutations in viruses? And they escape and kill everybody? And what about bacteria? IS THE LHC sterilized?
By the way, regarding your juvenile opinions on environmentalism and all that, I think it is hilarious that physicists get off on treating engineers as crackpots when they express their uneducated opinions on physics, but don't see any problem with a physicist, (who's never designed a manufacturing plant, know nothing about chemical engineering, and have never applied for an air quality permit and has no degrees in any sort of engineering or chemistry etc.) expressing their heart-felt opinions on the environment.
Uh, by "juvenile opinions" of course I mean the opinions you had as a youth.
Hi Carl,
I'd guess 1.9 K and 10^-13 atm is pretty much sterile ;-)
I actually don't know what you are referring to with physicists treating others as crackpots. I certainly have no problem with anybody expressing heartfelt opinions, and I don't think I've ever called somebody a crackpot? I am really sorry for all those people who are sincerely worried, having had plenty of worries myself as a teenager many of which later turned out to be due to exaggerated and/or unscientific reporting (growing up in a time of AIDS, Czernobyl, and Germany having lots of environmental problems one got to read and hear a lot that 10 year olds could get wrong). Yes, I am still worried about many environmental problems, but I usually don't write scary stories about them or declare the end of the world is due this year exactly because my knowledge is rather limited. My concerns about these issues btw lie dominantly on the political side (e.g. do our institutions manage to deal with them appropriately and in a timely manner). I am not sure if that addresses your comment but my problem is that unbalanced news reporting rather generally makes sensible discussions very hard, and reporting with the only purpose to scare people is just inappropriate. Best,
B.
PS: Also interesting, spell-check wants to replace Czernobyl with Cleanable.
I guess the only black hole would be the one in the standard theory if they don't find traces of Higgs.
Beautiful girl in the video though. Beauty should always be excused in my opinion:)
P.S Congratulations Bee for another detailed and complete post.
Hi Bee,
Another great post with even more explained. To be truthful though it was the venom I enjoyed the most and it was long overdue. I for one think too often the scientific community pussy foots around with people who have no intention in attempting to understand anything except their own unfounded opinions. There are many who are motivated by irrational fear and I must say I feel sorry for them, for like those that are afraid of heights, flying, confined spaces, rollercoasters or the boogey man, as we can do nothing for them, other then hope they seek out the help they need.
However, there is a second group that I am more wary of and those being the ones with some agenda other then what they would have us perceive as being only legitimate concern. They use unethical tactics, such as extreme exaggeration or even outright lies. They post what looks like informed and concerned web sites, which often screen comments before release. This serves to give one an unbalanced perception, which of course is the whole point to the tactic of censorship. They also find there way into print media, radio and television with practices much the same. These are the ones that shouldn’t be trifled with. They should be the ones threatened with civil and even criminal action as to show that there are consequences for their actions; and they are not immune simply because they claim their intent is to save us all and for our own good.
So as a first step, I would recommend those at CERN not only address this law suit, yet go further and file a counter claim, seeking damages for themselves and the related scientific community in general, whom these people have both slandered and libeled. It’s clear to me what must be done when the fox is in the hen house. I say stop with the defensive poster and go on the offence, for otherwise you play by rules they don’t hold themselves to and depend you will.
Best,
Phil
P.S. I guess Uncle Al is having a effect on me:-)
You may count me in for number 4: I am not 100% convinced that if black holes are produced at LHC (e.g. in some large extra dimensions scenario) the Hawking calculation applies to them: In that calculation you look at a free quantum field at infinity in the spacetime of a semi-classical black hole.
The microscopic black holes LHC could produce however would not be semi-classical, the curvature on the horizon would actually be Planck scale. Thus pure Einstein gravity is unlikely to be the correct description close the the horizon and the free quantum field might be a bad approximation as well.
Furthermore, the black hole in the Hawing calculation is nearly static: We see the radiation but what we compute is QFT in a fixed background geometry. For macroscopic black holes this is an excellent approximation and there you use conservation of energy to conclude that the bh gets smaller.
For the microscopic bh you are --- as you explain --- close to the moment where disappears. Again, this is obviously not quasi static and this raises the issue of remnants and how you get rid of them (a quantum gravity question probably).
All I am saying is that I don't think we have a very well controlled theory of microscopic black holes and the last stages of their decay. But still all the other points are very valid and thus even is the black hole (or some remnant) stays with us it would not be of any danger since I would expect it to look pretty much like any other elementary particle.
Hi Bee,
Nice post! This guy doubts that a BH radiates:
http://de.arxiv.org/abs/gr-qc/0607137
It seems that he submitted a first version of the above paper to PRL. It was rejected, of course. It is amazing that PLA dares to publish that!
Flavio
Hi Flavio,
Thanks! Will have a look. At first sight it seems he doesn't like the usual vacuum definition and therefore wants to reinterpret the result (he gets the usual temperature, see Eq. (61)). Best,
B.
I think Robert hit the nail on the head. Semiclassical black holes are created by the old fashion way of matter accumulation and are of no concern to the LHC. This is the type of black hole that 99% of the public is aware of. The microstate black hole is a different animal in that it is associated with the quantum gravity regime (Planck scale) which again is unlikely at LHC. There is simply not going to be a microstate black hole created which is near Planck density at the LHC level. Scattering processes will prevent this all the way up to GUT level.
Hi Robert,
Yes, the exact characteristics of the evaporation are not very well understood. This is one of the reasons why I don't work on the topic anymore. One can make all kinds of exact calculations of greybody factors and bulk/brane ratios and include supersymmetry and rotation and whatnot. But point is, how the final decay looks like is unknown. It is also unclear how the evaporation affects the temperature, since the black hole doesn't really have time to thermalize. So there's two possibilities that people consider: it either just decays instantaneously without the temperature changing. Or the temperature adjust after each emission (not in the microcanonical approach that Hawking used, but in the macrocanonical, so it doesn't have the unphysical divergence). Either way, they evaporate. What I'm saying is just that I found it's at a point where one would have to just go and measure before adding more and more details. One should also take into account that since the LHC is a hadron collider almost all of the black holes produced will have the smallest possible masses close by the threshold and essentially only make the final decay about which we know the least. The heaver ones are exceedingly rare.
Best,
B.
Hi Mark,
Depends on where the Planck scale is. As I said above the QG effects get weaker with the com energy (mass of the hole) increasing, so the not-classical effects go with powers Mass/Energy. As I wrote above I agree with Robert that for those BHs that are really directly planckian one doesn't know much, and I actually don't think we will know much until we have a theory of qg. Maybe you find Giddings summary interesting reg. semi-classical approx (see also references therein). Best,
B.
Abandon civilization to avoid UNKNOWN HAZARDS! Plastic water bottles are bad. Goatskins are good (dialectic obtains the goat part). Enviro-whiners ooze fear without comprehension, i.e., religion.
Is the antichrist circumcised? (especially important if the antichrist is a girl via CP inversion)
Off-center [lightspeed - epsilon] nuclear collisions create positively charged Kerr-Newman black holes. As electrons ultra-relativistically swirl in they will be electromagnetic pulse weapons imploding every iPhone, iPod, and X-Box on Earth. Know the fear, do it anyway.
Thanx Bee for the refs. I think it may be correct that all a microstate black hole wants to consume are thermal photons and not matter. Perhaps its the result of early cosmological conditions (QG). Who knows?
mark
Thanks for another great post B; it must be annoying to have to repeat oneself over and over ...
Phil - your second paragraph "However...good" seems to describe the present US administration almost exactly. Very scary indeed; unfortunately, they seem immune to prosecution at the moment.
Best.
Thanks :-) Well, I try to tell myself each time I repeat it, a few more people will get the message. Best,
B.
Hi Bee
The material you post brings together valuable material on whether or not there would be a risk from the LHC. My comments are on a few points which I think weaken your argument, generally by appearing to be somewhat unfair. They are offered in the spirit of hoping the LHC can be shown to be safe and operate.
A few selections from your post and comments :
"…YouTube video "The LHC-- the end of the world again?" showing a teenage girl in a garden babbling (my emphasis)"
Incorrect argumentation - ad hominem
"When I was that age I was worried about soil erosion, overfishing, acid rain, desertification, the greenhouse effect, global political instabilities, deforestation, air- and water pollution, population growth, nuclear waste, overuse of fertilizers and pesticides, and a dozen other 'unnatural situations' that are still problems today (and that I'm still worried about)."
Incorrect argumentation - red herring
"So here's my message to the YouTube generation: if you have too much time on your hand, and have already re-applied make-up three times today…"
Incorrect argumentation - ad hominem
"Following some further links, I eventually came via another video titled "Did Nostradamus predict the LHC will create a Black Hole?" "
Incorrect argumentation - straw man. Because some clearly crazy people support one side of an argument doesn’t mean the argument is necessarily wrong.
"Hawking showed in '75 using quantum field theory in the curved spacetime caused by a collapsing matter distribution that black holes emit thermal radiation."
Can you be more precise in language? As a scientist - although not a physicist, but with a paper in Nature - to me in the scientific method, the use of “showed” means “empirically demonstrated”. I don’t think Hawking or anyone else has done this.
"About the claim that the LHC's risk report is biased because it has not been performed by people at "arm's length". Yes, to get a reasonable report about the difficulties the LHC might be facing I would think you ask experts. These experts are usually people working in the field. Would you prefer them to be random sampled from a phone-book (my emphasisis)? "
Incorrect argumentation - straw man. That’s not the only alternative. Richard Posner in his Oxford University Press -published book gives another recommended makeup of an assessment panel - and it’s not just physicists.
"Finally, let me say that there is always some amount of uncertainty in everything we do. Yes, there is the possibility we are all wrong."
But not all errors have this particular worst-case scenario attached to them.
"There is also the possibility that you wake up tomorrow morning an have turned into a monstrous bug, because a cosmic ray has modified some virus to being capable altering your DNA. Or, as Arkani-Hamed put it so aptly in the recent NYT article: There is some minuscule probability, he said, “the Large Hadron Collider might make dragons that might eat us up.”"
Incorrect argumentation - straw man.
"I, and I believe many of my colleagues, would really appreciate if the media - TV, print and online - would not support such catastrophe-scenarios and scientifically completely absurd scary stories just because they sell well. "
Incorrect argumentation - ad hominem. How do you know that is their motive?
"If you are running out of topics for the science section, why don't you go and ask some scientists for inspiration?"
Leave war to the generals? Lucky Kennedy didn’t do that in the Cuban missile crisis.
Regards
LW
Hi LW,
Well, thanks for your thoughtful comment. You have however misunderstood my mentioning of the YouTube videos. This is not an 'argument' of any kind, and I have never pretended so. It is simply a demonstration of what you find out there.
- If you think 'babbling' is an 'ad hominem' attack, I apologize profoundly.
- It is not a red herring, because I don't discard discussing the actual topic for it.
- The Nostradamus quote isn't a straw man argument because I don't 'attack' it in exchange for the actual point. In fact, you might have noticed I don't comment on it at all.
- Again, you completely misunderstand my mentioning of the YouTube generation. It is not their argument that I am 'attacking'. I am just expressing my opinion that they could use their time better, and I think I make it pretty clear that it is my opinion.
- If you think 'showed' means something with 'seeing' empirically, then maybe 'derived' would have been more exact? However, I am very used to the word 'show' meaning to show from A follows B.
- I see. You are correct. It was meant to be a joke.
- It is not an ad hominem attack. First because this too is not part of the argument to begin with. Second because I do not claim this is their motive. I say, if this is the motive, then they shouldn't fall for it.
- I didn't say to leave it over to the scientists. Gee, certainly not! I was just suggesting that instead of repeating the same stories over and over again to maybe ask some scientists what they would like to see reported on.
Best,
B.
Btw, the girl in the first video has in my perception a somewhat confused line of thought, but she doesn't say anything plainly wrong. I think she's reading off the more complicated parts somewhere. Best,
B.
Hi Bee,
There is a post on ArXiv tonight, "Accelerator Disaster Scenarios, the Unabomber, and Scientific Risks." Seems that fear of accelerators destroying the world has a history. The article is also an account of the author's personal experiences in physics -- so it's not a short read.
Best, Kris
You can download youtube (and other) videos with the help of this site. Or grab them from cache while you're still on the youtube page and the video has finished downloading (on macs the location is something like /var/tmp/folders.501/TemporaryItems/FlashTmp0).
Hi Kris,
Thanks for pointing this out, I would probably have missed it! I will give it a read. Best,
B.
Hi Ivan,
Thanks! I should probably say, by now I have like three different versions of that video. So thanks everybody for the help! And yes, it will go into my next week's talk (amazingly enough, I managed to embed it into pdflatex). Will let you know what the audience thinks :-)
Best,
B.
The article by listed by Kris Joe Kapusta( I included another point to consider in context of Joe) is a good read. I learnt of him through Peter Steinberg and his lecture in Flicker up loaded by him on August 9, 2005.
This article goes to the point I made earlier, by how one might scoff at the ridiculousness of the idea of strangelets( how they came about in relation to the issue at hand)about what scientists actually know outside of those who are directly dealing with the work.
What is important, is that "LW" is being placed their amongst the originations of the research that was coming out. "A Lawyer" and "a scientist?"
Now we know how Peter Steinberg is dealing with this directly and how Cern is also answering the process most intelligibly.
It did lead to a greater understanding by looking into the QGP process that Joe is talking about in it's development, also, leads one to consider the context of what is evident in Grans Sasso and the area Joe is now working.
This relationship is what I found in concert with the Pierre Auger experiments( the awarenss of cosmic rays and John Ellis's work, and the issues of GZK cutoff and the historical development of the Flys Eye, and the "Oh my God Particle" issue then.
I would caution then those scientist who clamour with such vociferously about the ridiculousness of what what is being done in terms of the challenge of law in that issue, is also the awareness of what scientists have now learnt retrospect, that stranglets had been proved not to exist and that the very term "God Particle," is, "the incredible nature of scientific research" that discounts the term in face of what it now knows.
So what is now incredulous in the news and the article that passes from one blog to the next heralded research into the new things that are relevant in the collision process?
I am not in support LW's challenge just that it be taken into consideration with a little more respect. The challenge is an adverse way in which to answer all the conditions and provide for the benefits of checking over the current situation with the relevant information. Nothing wrong with detailing the facts as we now know them. I believe Cern is already dealing with them responsibly. They did it with the strangelets.
Is that the best you have... I will focus on the micro black hole argument, that is what the $500 contest at LHCConcerns.com is about , present a proof of 5% or lower risk from micro black holes... Should be easy, correct?
[quote]So, here is again all the reasons why the LHC isn't going to create a black hole that will cause the end of the world:
1. To begin with, please notice that the creation of a black hole at the LHC is *not* possible in the standard framework of Einstein's theory of General Relativity. To produce black holes at the energies LHC can reach, it needs a modification of General Relativity at small distances. This could potentially be the case if our world had large extra dimension. There is however no, absolutely no, evidence so far this is really the case. The scenario is pure speculation, a hypothesis, a theory, or call it wishful thinking [1].
[/quote]
Sorry, CERN predicted creation of up to 1 micro black hole per second. Have CERN publicly and strongly completely retract that prediction and I will give your argument more credit. Currently, you are talking out of both sides of your mouth. CERN either predicts the creation of micro black holes or they do not. They do. Further, the March 2005 RHIC bose-nova implosion created a Bose-Einstein condensate and thousands of atoms could not be accounted for. According to one Nobel prize winner it was "probably not a black hole". I hope he was correct. Because what ever was created, it was stable and it disappeared.
[quote]
2. It is not only that there must be compactified extra-dimensions, but the parameters of that model (their size and number) have to be in the right range. We know that the case with one dimension is excluded, and two should also already have shown up in sub-mm measurements, so this case too is strongly disfavoured. There are further various constraints from astrophysics that put strong bounds on the cases with three and four. But most importantly, there is no good reason known why these extra-dimensions should have the radius they need to have so quantum gravity is observable at the LHC - no reason other than it would be nice to have it shown up at these energy scales.
[/quote]
This is supposed to be convincing... to who?
[quote] 3. Now to come to the issue of the black holes should they be created. Hawking showed in '75 using quantum field theory in the curved spacetime caused by a collapsing matter distribution that black holes emit thermal radiation. The temperature of this radiation is inverse to the radius of the black hole. The black holes that would be produced at the LHC would be extremely tiny, ~ 10-18 meters, and thus be extremely hot ~ 1016 K (that's a 1 followed by 16 zeros). They would decay within a time scale of roughly 1 fm/c, that is 10-23 seconds. They would not even reach the detector, instead they would decay already in the collision region. The only thing that could be measured are the decay products.
[/quote]
Hawking Radiation has been disputed by no less than 3 rigorous peer reviewed studies that found no basis in science for such a conclusion. This is science fiction that requires Einstein to be doubly wrong in Professor Hawking's opinion. And we should believe professor Hawking why, because he has had how many theories proven correct correct in his very long career, he has won how many Nobel prizes since he completed his academic career with a sterling C average? Give me a break.
[quote] 4. The temperature of these black holes is so hot, they can not grow even if they pass through matter of very high density, like e.g. a gluon plasma or a neutron star. The mass gain from particles coming in the black hole's way (which depends on the density) is far smaller than the mass loss from the evaporation. The density of the earth is further several orders of magnitude smaller than that of nuclear matter, so there is no way the black hole could grow. Even if you assume the black hole has a high γ-factor (and thus experiences a higher density), this is not sufficient to enable it to grow.
[/quote]
And you know better than Professor Rossler who has been described by the 'Zero Risk' crowd as prestigious but, eminent but, world recognized but... And Albert Einstein was 'just a grad student'. Professor Rossler is one of the worlds most respected scientist geniuses, his list of scientific accomplishments is staggering. He did the math. 50 months accretion time. Where is the rigorous peer review rebuttal? Where is LSAGs Earth Accretion math? LSAG writes that they do not assume that micro black holes will be stable. So where is the rigorously peer reviewed Accretion math? It is only the fate of the planet, no math?
[quote] 5. Hawking radiation is *not* a quantum gravitational effect. Hawking's calculation uses two very well known ingredients that are classical General Relativity and quantum field theory. It is true that we do not know quantum gravity, but quantum gravitational effects would only become important in the very late stages of the decay, when the black hole comes into the quantum gravitational regime. This would then affect the observables (and this ambiguity is thus somewhat of an annoyance), but it does not mean the black hole could grow. The reason is that if the black hole grew, it would come into the regime where Hawking's calculation applies to very good approximation, and it would lose mass as predicted. The scale for quantum gravitational effects to be important is the curvature at the horizon, which falls with M/R3 when the black hole grows, where M is the mass of the black hole and R is its radius (which again is a function of the mass).
[/quote]
Hawking again, not credible. The GLAST satellite will look for signs of Hawking Radiation this summer, are you planning to start up the Large Hadron Collider before this satellite might fail to find the mythical Hawking Radiation. The following is what one professional physicist that I highly respect said of Hawking Radiation and possible quantum effects on micro black holes...
[quote]
"Hawking Radiation" is a hoax. Quantum theory should actually likely require a blackhole to grow larger, not smaller, if it were to effect a blackhole. Here's why.
Separating "virtual particle pairs" into real particles is not difficult, nor is creating antiparticles.
We routinely make antiprotons at Fermilab, etc. We slam high-energy protons into a Nickel target, with kinetic energy of about 2 orders of magnitude more than the rest-mass of a proton [about 0.94 GeV]. Out pop all kinds of particles and antiparticles, including antiprotons, which we magnetically separate, store, and later accelerate and collide into protons.
These scenarios always require an input of energy at least equal to the rest-mass of the particles created. For the radioisotope, this energy comes from the mass of the nucleus itself, which is reduced slightly when the positron is emitted. For making antiprotons, it comes from the kinetic energy of the proton beam striking the target.
Hawking's idea of evaporating black holes does not require input of energy to create particles. Instead, he believes that two particles [the particle and its antiparticle] will come into existence at the 'event horizon' as virtual particles, with one falling into the black hole, the other wandering away [as "Hawking Radiation"]. Because the one that wandered away became real, the one that fell into the black hole must have the equivalent of negative mass, thereby reducing the mass of the blackhole, preserving the total mass of the system.
That is the hoax. Negative mass. No such thing. If there were, the negative mass particle would more likely be repelled from the black hole [the opposite sign would make for gravitational repulsion, not attraction], not falling into it. The net result would be that black holes would spontaneously slowly grow larger, not evaporate, robbing via quantum tunneling from nearby matter. However, I believe they would just sit there unless matter directly fell into them. Either way, "Hawking Radiation" would not exist.
It is, of course, utter lunacy to use as a "safety argument" the idea that "Hawking Radiation" will evaporate the microblackholes they hope to make in the ATLAS detector. [/quote]
[quote] As to the claim that there are 'people' who doubt black holes radiate, let me first reduce 'people' to 'physicists' since there are apparently also 'people' who doubt that the earth is more then 20,000 years old, or is a sphere (at least to very good accuracy). I know exactly no physicist who doubts that black holes radiate. The one work that I know of has sometimes been referred to is that by Adam Helfer. However, even he states in his paper (gr-qc/0503053) explicitly: "[These results] do not, as emphasized above, mean that black holes do not radiate [...]" [2].
[/quote]
Talk to me about science that is NOT REFUTED by rigorous scientific studies over and over and find NO BASIS IN SCIENCE. Give up Hawking Radiation, LSAG has "we do not assume that micro black holes will evaporate..." and your peers have. Hawking Radiation is not science. It is rigorously disputed speculation that has no basis in reality.
[quote] 6. As has been said many times before, the earth is constantly hit by cosmic rays which undergo in interactions with particles in the earth's atmosphere collisions with a higher center-of-mass energy than the LHC will reach. If it was possible to produce a black hole this way which would then swallow the earth, this would not only very likely already have happened some billion years ago, but we should also see stars disappearing more often, especially neutron stars because of their high density. There is no evidence for that.
[/quote]
Your own LSAG (LHC Safety Assessment Group) presented to the University of Berkley not too long ago and conceded that cosmic ray impacts with Earth would send ALL particles created safely into space. Even the 1999 RHIC safety study conceeded that cosmic ray impacts are not equivalent of collider collisions. Why did CERN not release a promissed safety report from LSAG. Because they did not want the creme of the worlds physicists to tear it apart, so they send Physics graduate students to peddle weak, non-peer reviewed science on blogs?
Now you want me to believe that a cosmic ray hitting a stationary particle would focus the energy to a single point the same way that a collider smashes same mass, exact same speed, exact opposite vector and in some cases exactly center mass collisions with particles traveling each at 99.9999991% the speed of light for a net collision speed of almost 2C focusing the energy precisely to a single point, and sometimes these collisions will involve protons with anti-protons. And you want me to believe that is the same as a stray proton with up to 10^20 eV of energy hitting a relatively stationary particle on Earth. I read the 1999 RHIC safety study, they admit that the momentums produced by cosmic rays do replicate head on collider collissions. Did you read the 1999 RHIC study? Are you trying to make false arguments? Or do you truly not understand basic physics?
[quote] 7. It has then further been argued that the black holes at the LHC would be created in a different center of mass system, and thus not have the same average velocity with respect to the earth. This is correct but there are two points to be said here.
[/quote]
Thank you.
[quote] For one, the protons at the LHC will be accelerated to 99.9999991% of the speed of light, which is really fast. I mean, really. If you bang them together it is extremely unlikely the created particles will be in rest or even slow moving relative to the earth. Indeed, as Stefan has explained very nicely previously, their velocity will typically be far higher than the escape velocity of the earth. Pictorially speaking, consider a car crash. Things usually fly around quite a lot, already at 0.0000001% of the speed of light.
[/quote]
I don't know if every single EXTREMELY DENSE micro black hole created will be captured by Earth's gravity. I would like to know. Because if even the first is likely or virtually assured to be captured, then shutting down the experiment as CERN promised in response Professor Rosslers very strong concern, will be of no use!
[quote] Second, even for the few black holes for which that wouldn't be the case, again, they would decay even before they hit the detector. In any case they would definitely not collect in the middle of the earth (or 'gravitate to the center of the earth' or whatever). This is a totally absurd idea that I have however come across several times. It is absurd because the center of the earth would generally not be on the produced object's trajectory (having an initial velocity), and even if it was they wouldn't stop in the center of the earth, why should they? Ever heard of energy conservation? As said previously, they are far to small (cross-section to small) to interact noticeably with the earth's matter so they wouldn't slow down. (If one really pushes it one can now go and estimate how long it would take them to slow down until they get stuck and so on. But frankly, this scenario is already so absurd that such a speculation is totally moot, and an utter waste of time, mine and yours.)
[/quote]
Excuse me, but you are repeating weak and disputed arguments... If it is scientific, then officially release it and have it peer reviewed. If you can not, then perhaps all you can do is have Physics grad students peddle this 'stuff' on blogs.
[quote] 8. About the claim that the LHC's risk report is biased because it has not been performed by people at "arm's length". Yes, to get a reasonable report about the difficulties the LHC might be facing I would think you ask experts. These experts are usually people working in the field. Would you prefer them to be random sampled from a phone-book? I honestly do not understand why anybody would think people working in theoretical physics have a larger interest in destroying the planet than other human beings.
[/quote]
LHC Safety Assessment Group never release a report. There is no report. That is a very strong statement in it self. What I am responding to now, is this the LSAG safety report? Are the scientists who wrote it are not willing to defend it? I don't blame them.
[quote] To be somewhat cynical here, you'd instead think that a lot of theoretical physicists should be really nervous about the LHC because it will test their theories. And no matter what, very many of these theories will be outruled, dead, speculations no longer viable. One of these theories that can be tested is the one with large extra-dimensions. And if it isn't found hundreds of people who have worked on it must face that they have wasted their time, their publications do not describe nature, and the topic is no longer something you can use for a grant proposal.
[/quote]
I don't know how many scientists I have read that said, "No danger", of course I have not bothered to look into it myself, I am busy. Of course, according the legal action, employees of CERN are requested to refer to the risk as zero, regardless of personal opinions.
[quote] 9. Finally, let me say that there is always some amount of uncertainty in everything we do. Yes, there is the possibility we are all wrong. There is also the possibility that you wake up tomorrow morning an have turned into a monstrous bug, because a cosmic ray has modified some virus to being capable altering your DNA. Or, as Arkani-Hamed put it so aptly in the recent NYT article: There is some minuscule probability, he said, “the Large Hadron Collider might make dragons that might eat us up.”
[/quote]
Fine, at least prove the risk is less than 5%, then I can sleep at night believing my children may have some chance of growing old.
There is a $500 challenge, just prove 5% or less risk with respect to micro black holes. How many grad students are so well paid that you could not use $500?
[quote]I, and I believe many of my colleagues, would really appreciate if the media - TV, print and online - would not support such catastrophe-scenarios and scientifically completely absurd scary stories just because they sell well. There is, in the community, no argument about whether mini-black holes at the LHC are a risk worth worrying about. The answer is simply no, they are not. The story about black holes created in particle colliders that swallow the earth came up first time in '99 regarding RHIC, so it has a long beard in 2008, and it's getting longer every day. If you are running out of topics for the science section, why don't you go and ask some scientists for inspiration?
I have no specific relation the theories investigated here, in fact, not being influenced by subjective preferences is part of what it means to be a scientist (whether we like that or not). I'm not telling you what I wrote here because I want money or publicity for collider physics, or any other reason of personal advantage you could accuse me of. I am telling you that just because black holes at the LHC is not something you should worry about. Worry about some real problems instead.[/quote]
I don't think I will sleep well tonight. Will you?
JTankers
LHCConcerns.com
Hi JTankers,
Thanks for your comment.
Sorry, CERN predicted creation of up to 1 micro black hole per second. Have CERN publicly and strongly completely retract that prediction and I will give your argument more credit. Currently, you are talking out of both sides of your mouth. CERN either predicts the creation of micro black holes or they do not.
It wasn't 'CERN' who made this prediction but Dimopoulos + Landsberg, but besides this you apparently have a problem with the word 'if'. It is a prediction IF the world has extradimensions and IF they have the right number and IF they have the right radius etc. (Besides this, the number one per second is somewhat outdated and has since then been corrected downward because the scenario is overly optimistic.)
Hawking Radiation has been disputed by no less than 3 rigorous peer reviewed studies
UUUh! AAAhh! Gee, three rigorous peer reviewed studies! I shiver for fear! Are those by the same two above mentioned people?
"Hawking Radiation" is a hoax. Quantum theory should actually likely require a blackhole to grow larger, not smaller, if it were to effect a blackhole. Here's why.
[...] That is the hoax. Negative mass. No such thing. If there were, the negative mass particle would more likely be repelled from the black hole [the opposite sign would make for gravitational repulsion, not attraction], not falling into it.
Your 'explanation' why Hawking radiaton can't work is a very sad example for popular science explanation gone wrong that I mentioned previously in this thread. The picture with the pair production at the horizon is very misleading. If you can, I encourage you to do the calculation. The brief explanation to your problem is the energy of the infalling particle is negative as measured by the observer at infinity because inside the horizon the time- and spacelike coordinates are exchanged so the energy has a sign change. This does not mean these particles anti-gravitate.
I don't know how many scientists I have read that said, "No danger", of course I have not bothered to look into it myself, I am busy.
What is that supposed to prove?
And you know better than Professor Rossler who has been described by the 'Zero Risk' crowd as prestigious but, eminent but, world recognized but... And Albert Einstein was 'just a grad student'. Professor Rossler is one of the worlds most respected scientist geniuses, his list of scientific accomplishments is staggering. He did the math. 50 months accretion time. Where is the rigorous peer review rebuttal?
My sincere apologies, but I have never heard of this this world respected genius. Btw, this argumentation is also called 'appeal to authority'. Anyway, it's nice somebody did the math. As I wrote in the text, I don't doubt you can do this calculation. What is there to rebut? If you make assumption A then you can calculate B. People do that all the time. It seems to me this is the same problem with the conditional statements you have with point 1.
Excuse me, but you are repeating weak and disputed arguments...
Well, thanks for letting me know it's me who repeats the weak and disputed arguments.
Now you want me to believe that a cosmic ray hitting a stationary particle would focus the energy to a single point the same way that a collider smashes same mass, exact same speed, exact opposite vector and in some cases exactly center mass collisions with particles traveling each at
I never said that, and I don't see any point repeating what I said above.
Why did CERN not release a promissed safety report from LSAG. Because they did not want the creme of the worlds physicists to tear it apart, so they send Physics graduate students to peddle weak, non-peer reviewed science on blogs? [...]
There is a $500 challenge, just prove 5% or less risk with respect to micro black holes. How many grad students are so well paid that you could not use $500?
I'm not a grad student. And I am very well paid, thanks.
Best,
B.
Are you telling me that the Earth is safe because you believe that Professor Hawking has proven that micro black holes evaporate. Is that what you are saying?
Are you telling me that you have not read the rigorous peer reviewed studies that found no basis in science to support such conclusions?
And you want me to believe you when you say "zero risk"? You can't even prove less than 5% risk.
Professor Hawking speculates that it might be possible for particles to travel back in time, Professor Albert Einstein considered such ideas to be paradoxical nonsense, not possible.
Professor Hawking speculates that black holes might sometimes shrink, decay, evaporate, again Professor Albert Einstein considered such ideas to be not possible, against the laws of nature.
Professor Hawking today speculates that it will be safe to create micro black holes on Earth in the Large Hadron Collider, because he believes that quantum fluctuations around black holes will steal energy from the black hole. He seems quite certain about his theory, while at the same time he dismisses and ignores his own peers who write rigorous peer reviewed studies disputing this theory as not supportable by science, disputes Professor Einstein who stated that not even light can escape a black hole, and apparently requires that vacuum energy does not exist. And Professor Hawking was recently quoted as suggesting that he should be awarded a Nobel prize for this idea. (Professor Hawking has never won a Nobel prize). ''' Credibility of Hawking Radiation is strongly disputed:'''
2008 ... this prediction is not without its problems... no very good responses to these concerns... completely alters the picture drawn by Hawking... http://arxiv.org/PS_cache/gr-qc/pdf/0503/0503052v1.pdf
2008 ... Max-Plank-Institut fur Astrophysik: The results indicate that on average, "low mass" black holes of less than a hundred million solar masses are still growing at a significant rate. http://www.mpa-garching.mpg.de/mpa/research/current_research/hl2004-7/hl2004-7-en.html
2004 ... it may be a long time before we have sufficient knowledge of quantum gravity to be able to calculate the correct answers for the logarithmic terms in the entropy. http://arxiv.org/PS_cache/hep-th/pdf/0409/0409024v3.pdf
2004 ... 9.9% average doubt, ranging from 0% to 50% doubt by 15 physicists polled: http://www.lhcconcerns.com/#James_Blodgett, even before much of the peer reviewed credible rejection of Hawking Radiation was published
2003 ... Yet this prediction rests on two dubious assumptions... no compelling theoretical case for or against radiation by black holes: http://arxiv.org/abs/gr-qc/0304042
1900s ... Albert Einstein's theories require that black holes only grow, they never shrink, not even light can exit a black hole
Recently when asked if the Large Hadron Collider was safe, Professor Hawking said "Particles from collisions far greater than those in the LHC occur all the time in cosmic rays, but nothing terrible happens.". What? (http://www.latimes.com/news/science/la-sci-hawking12apr12,1,3191870.story))
Even CERN's own LHC Safety Assessment Group has conceded the that cosmic ray impacts with Earth could not endanger Earth, because unlike paricles created by head-on collider collisions, cosmic ray created particles travel too fast to be captured by Earths gravity and are all safely expelled into space at relativistic speeds, and the same LSAG group stated that they do not assume that micro black holes will evaporate. But CERN never released any safety reports created by LSAG.
JTankers
LHCConcerns.com
LHCConcerns.com will pay $500.00 US to the best proposal that can reasonably prove 5% or less Risk of Planetary destruction from Micro Black Holes.
The contest will conclude in a vote by site visitors on all reasonable proofs received, all proofs will be published and the contest will end not sooner than May 20th.
(LHCConcerns will make the final call on best proposal that reasonably proves 5% or lower risk from micro black holes being created by the Large Hadron Collider).
You may prove that ANY ONE of the following or provide any other reasonable Proof or method to prevent Micro Black Holes from being created by the Large Hadron Collider or prove that they are harmless!
1. The Large Hadron Collider will not make micro black holes.
2. Micro black holes created will be sent safely into space.
3. Micro black holes will evaporate.
4. Micro black holes will take more than 2 billion years to accrete the Earth. (If you can only prove a lesser time frame, then the prize will be reduced proportionately...)
5. Any form of cosmic ray argument that proves 5% risk or lower.
6. Find a way to make the Large Hadron Collider safe from creating micro black holes (we already requested different speed collissions or different mass collisions, LSAG told us it was not possible, they already thought of it).
It is harder than it looks, the LHC Safety Assessment Group (LSAG) could not produce a safety report...
(CERN and LSAG are still using the 1999 RHIC safety report that does not even address what might happen if micro black holes were created, because they did not know that it was possible at that time. We are also being generous on the 2 billion years, we want to be reasonable)
JTankers
LHCConcerns.com
Hi JTankers,
Your comment is completely ridiculous. I hope you are aware that with this 'argumentation' you are very efficiently undermining your own credibility. You have not brought up a single scientific argument. All you do is quote other people, and you have already demonstrated your lack of basic knowledge about the topic you are discussing.
Are you telling me that the Earth is safe because you believe that Professor Hawking has proven that micro black holes evaporate. Is that what you are saying?
I never said that. I believe the earth is save because I read Hawkings papers, did the calculation, read numerous other works on the topic (I recommend Birrell+Davies), did the calculations. Asked all the questions you too seem to have (e.g. the one about the negative energies), and convinced myself these derivations are physically and mathematically sound. I also did the calculations for the case of higher dimensional black holes, I read dozens of publications on the topic, I wrote my master's thesis on the Hawking effect, and my dissertation on the properties of mini-black holes.
Are you telling me that you have not read the rigorous peer reviewed studies that found no basis in science to support such conclusions?
I certainly missed one or the other publication on the topic. As I wrote in the text above I read the publications by Helfer that have been referred to, and that you too are referring to in the first quote. It seems to be pretty much pointless in discussing with you the details of this work given that I have the impression you don't know very much about the Hawking effect, but as I mentioned above, Helfer wrote himself explicitly "[These results] do not, as emphasized above, mean that black holes do not radiate [...]"
As to your second reference, this is about astrophysical black holes of very large masses so I do not know exactly what your argument is. Anyway, the full context to that sentence you cropped from that website is
"The results indicate that on average, "low mass" black holes of less than a hundred million solar masses are still growing at a significant rate. The team also measured the star formation in nearby low mass bulges and deduced that rate at which new stars form in these systems is a thousand times larger than the rate at which their black holes are growing. This factor of a thousand is in gratifying agreement with the ratio between bulge and black hole mass observed in inactive galaxies!"
The third reference by Don Page is a great paper! In fact, I recommend you read it. I already said above it is correct that we don't know quantum gravity.
The fourth 'reference' is a joke, right?
The fifth reference is by the same person as the first. If you had read this paper you'd have noticed that almost all of the 80 pages is a very nice summary of other people's research. There is no calculation supporting the claim you are making that black holes do not evaporate. Neither is there a calculation in the later papers, in fact he states he can not compute anything.
I find it very interesting that you are so very critical about the idea of pair production in the Hawking effect, but are completely uncritical with the idea that particle pairs of arbitrarily high energy can be prodouced in the asymptotically flat region, as Helfer seems to claim. It is of course hard to say whether this is in disagreement with observation without an actual calculation.
Besides this 'Rept.Prog.Phys.' isn't exactly a high-impact journal. I doubt it was the first journal this paper was sent to which means it was likely rejected in peer review several times (but this is just a speculation)
Okay, so where are the many thoroughly peer reviewed publications disputing Hawking radiation?
Best,
B.
BTW, just for completeness, the preprint of Rössler is here:
"Abraham-Solution to Schwarzschild Metric Implies That CERN Miniblack Holes Pose a Planetary Risk."
He has also written A Petition to CERN, Honey, I shrunk the earth!
He has presented these ideas on a congess called "transmediale 08 - CONSPIRE...", as a keynote with the title The Paradox of the Big Bang: Reducing Fear by Accelerating Danger. Maybe he is just making a big joke.
Cheers, Stefan
Ah, Rössler with ö, and he's a chemist not a physicists, that's why googling Rossler physics doesn't give anything useful. Here is what Wikipedia says
Otto E. Rössler (born 20 May 1940) is a German biochemist.
Rössler was born in Berlin. At the age of 17, he became an amateur radio operator (DR 9KF). After considering becoming a monk, Rössler chose to major in medicine, with a specialty in immunology, for ethical reasons.
He was awarded his MD in 1966. Rössler then began his post doc at the Max Planck Institute for Behavioral Psychology, in Bavaria. In 1969, he started a visiting appointment at the Center for Theoretical Biology at SUNY-Buffalo. Later that year, he became Professor for Theoretical Biochemistry at the University of Tübingen. In 1976, he became a tenured University Docent. In 1994, he became Professor of Chemistry by decree.
The pdf you linked to above is actually two papers. Regarding the questions whether it's a joke, read the last two paragraphs (on page 6). He ends his acknowledgements with the sentence "Paper submitted simultaneously to Science, Nature and Z. Naturforsch. to get the best criticism of the world, with the publishing rights going to the one who accepts first."
Anything to add?
Hi Bee and Stefan:
Thanks for the link to Roessler's petition. I hadn't seen it before, though I was aware of his paper estimating as little as 5 years for earth accretion by an accreting black hole.
I believe the problem that most people have with Hawking's idea is that, generally, there would be three different possibilities for a black hole sitting in the vacuum of space.
First, of course, under Einsteinian theory, it would simply just sit there, unchanging, unless matter were to come nearby and fall into it. That was the original theory, of course, before Hawking began talking about 'quantum effects' at the 'event horizon'.
We of course make particles and antiparticles every day. In our nuclear medicine departments, every day [including today] we slam protons into O-18 to make F-18, a positron emitter. When the F-18 decays [fairly rapidly because of its short half-life, which means we need to actually make it several times per day in some of our facilities], the nucleus loses a little bit of its mass, which is converted into the mass of a positron [and a neutrino], as well as their kinetic energies. This is then quickly converted back into energy, as the positron only travels about 1 millimeter before it encounters and electron, annihilating with two opposite-momentum photons of about 511 KeV each.
We also routinely make antiprotons by slamming high-kinetic energy protons into targets, creating lots of particles and antiparticles, some of which are antiprotons, which we then magnetically separate, store, and later collide with protons [as at Fermilab].
We always need to inject energy, however, to make such particles.
Hawking believes that the energy of the black-hole, however, can provide the mass for particle creation. While the idea is interesting, it is entirely different than what we do in the laboratory.
To sum up his idea, he envisions that a particle and antiparticle form at the event-horizon as virtual particles. When one falls into the black hole, the other wanders away, and now isolated, required to become real. Consequently, the other that fell into the black hole is required to reduce the mass of the black hole [to conserve total mass], being the equivalent of having 'negative mass'. That is the other odd thing about his idea.
It could be just as easily argued that a black hole would accrete a positive mass particle, requiring a nearby antiparticle to disappear.
However, in the vacuum of space, there would be no nearby particles, and such scenario would likely be suppressed, just as Electron-Capture radioactive decay is altered or suppressed if the nearby electrons take a different chemical configuration, or are absent [preventing the decay].
Regards,
Walter L. Wagner
Dear Dr. Wagner,
thank you very much for your comment, and the nice explanation of positron emission tomography.
However, with respect to your discussion of the Hawking effect, maybe you read carefully again Sabine's replies to JTanker, especially the paragraph "Your 'explanation' why Hawking radiaton can't work ..." ?
Moreover, I strongly suggest that whoever on this blog starts again to discuss the Hawking effect on the basis of the hand-waving "antiparticle falls into the horizon" argument will be banned forever, for inflicting insufferable mental pain on the host, Sabine.
Thanks, Stefan
Stefan:
Thanks for your response. I did as you suggested and read again from Jtankers, from which I quote Bee's response thereto:
"The brief explanation to your problem is the energy of the infalling particle is negative as measured by the observer at infinity because inside the horizon the time- and spacelike coordinates are exchanged so the energy has a sign change. This does not mean these particles anti-gravitate."
That is the problem that some physicists have - namely that "the energy of the infalling particle is negative".
While that does add up to zero net energy change [negative energy for the infalling particle, positive energy for the "Hawking Radiation" particle], thereby preserving the fundamental law that matter/energy is neither created nor destroyed, just changed in form, it poses a significant challenge to physics.
While the concept mathematically might be correct, in physics there is no demonstrated valid concept of "negative energy". This is a cute concept that is contrived to allow creation of a real particle/antiparticle ["Hawking Radiation"] without violating the law of the conservation of mass/energy.
While I am not asserting that it has to be wrong, it simply does not seem to be provable to be true.
It seems that it might also be true that a black hole might simply have a particle/antiparticle that is one of two newly-created virtual particles at the event-horizon fall into the black hole, thereby requiring any nearby particle/antiparticle to instantly vanish [without having to move through space to the blackhole], in order to preserve the total mass/energy of the system. This alternative explanation indeed seems even more plausible than Hawking's idea, though personally, if I were a betting man, I'd bet that neither occurs, and the black hole simply sits there unchanging until some stray matter falls into it.
Regards,
Walter L. Wagner
Dear Dr. Wagner,
That is the problem that some physicists have - namely that "the energy of the infalling particle is negative" [...] While the concept mathematically might be correct, in physics there is no demonstrated valid concept of "negative energy". This is a cute concept that is contrived to allow creation of a real particle/antiparticle ["Hawking Radiation"] without violating the law of the conservation of mass/energy.
Are you saying you are suing CERN because you think Hawking evaporation requires particles of negative energies?
Who are the 'some physicists' that allegedly have this problem? Would you be so kind to point me to a publication?
Best,
B.
Perhaps I can answer the Doctor's question: Dirac's equations (which will not fit in a comment) lead to values of energy E that are positive or negative. The negative solutions are considered positive states of antimatter. Dirac's equations lead to prediction of the positron.
Just to be remindful, positrons have positive mass, antiprotons have positive mass, antineutrons have positive mass, etc.
It takes real [positive] energy to create those real particles in a laboratory setting.
Regards,
Walter L. Wagner
Could you please explain to everyone reading this what happened in March of 2005 at the RHIC. Could you please explain what you think happened to the thousands of atoms that were not accounted for?
Do you think it is possible that the mass is still growing? If not, then why?
"A bosenova is a very small, supernova-like explosion, which can be induced in a Bose–Einstein condensate (BEC) by changing the magnetic field in which the BEC is located, so that the BEC quantum wavefunction's self-interaction becomes attractive.
In the particular experiment when a bosenova was first detected, this procedure caused the BEC to implode and shrink beyond detection, and then suddenly explode. In this explosion, about half of the atoms in the condensate seem to have disappeared from the experiment altogether, remaining undetected either in the cold particle remnants or in the expanding gas cloud produced.
Under current quantum theory, this characteristic of Bose–Einstein condensate remains unexplained, because the energy state of an atom near absolute zero appears to be insufficient to cause the observed implosion."
March 2005 http://news.bbc.co.uk/1/hi/sci/tech/4357613.stm (Poor article fails to mention thousands of missing atoms and instead assumes radiation, there were missing atoms that may have clumped, not radiation that would have been detected.)
http://en.wikipedia.org/wiki/Bose_einstein_condensate#Unusual_characteristics
http://news.bbc.co.uk/1/hi/sci/tech/4357613.stm
http://arxiv.org/PS_cache/hep-th/pdf/0501/0501068v3.pdf We argue that the fireball observed at RHIC is (the analog of) a
dual black hole.
http://en.wikipedia.org/wiki/Bosenova
In the particular experiment when a bosenova was first detected, this procedure caused the BEC to implode and shrink beyond detection, and then suddenly explode. In this explosion, about half of the atoms in the condensate seem to have disappeared from the experiment altogether, remaining undetected either in the cold particle remnants or in the expanding gas cloud produced.
JTankers,
In case you haven't noticed this post is about black holes at the LHC. From your sudden change of topic I assume you have nothing to reply to what I said above. For your other confusions, please consult somebody else, my time is finite.
Best,
B.
PS: You might want to clarify the words 'fireball' and 'dual black hole' before you make a complete fool out of yourself.
Hi Louise, Thanks for your help :-)
Dear Dr. Wagner,
Just to be remindful, positrons have positive mass, antiprotons have positive mass, antineutrons have positive mass, etc.
Correct. So what is your problem then? It's a tunnel effect. Particle out with positive mass, leaves behind missing positive mass. (I am not sure what Lousie was trying to say above.) Recommended reading: Parikh and Wilczek: Hawking Radiation as Tunneling. As mentioned above, I explained previously why I dislike the explanation with the particle pairs at the horizon. If you're to inflexible to rethink, maybe ask yourself where usually the energy for particle production in a strong background field comes from. Hint: it doesn't happen without the background field.
Could you do me a favor and answer my question: Are you suing CERN because you think Hawking evaporation requires particles of negative mass?
Best,
B.
B. writes: "PS: You might want to clarify the words 'fireball' and 'dual black hole' before you make a complete fool out of yourself."
Those are not my words, they are the words used in the peer reviewed study posted on http://arxiv.org/PS_cache/hep-th/pdf/0501/0501068v3.pdf.
The title is "The RHIC fireball as a dual black hole" by Horatiu Nastase of Brown University. Dated March 22, 2006.
It is clear you have not read the peer reviewed study of this incident. Please also research the thousands of missing atoms, the wikipedia article on Bose-Einstein condensate is a great starting point. I can also point you to the Nobel laureate on the team if you need assistance.
Hi JTankers,
Congratulations. You've ignored my advice and made a fool out of yourself. I read somewhat more than the title of that paper, and I also know what they are talking about. I am not presently in the mood to talk about Bose-Einstein Condensation, please excuse me, but I've got a paper to write. Best,
B.
Hi Bee:
It looks like we both have people jumping to our respective 'sides' with less-than-correct explanations. C'est la vie.
Yes, I have also read that "Hawking radiation" can be equated to a particle or anti-particle quantum-tunneling beyond the 'event horizon'. I don't believe that explanation either is absolutely required. Perhaps it's possible, perhaps not.
It gets back d