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Black holes hype does not decay February 3, 2009

Posted by dorigo in astronomy, Blogroll, cosmology, humor, news, physics, politics, religion, science.
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While the creation of black holes in the high-energy proton-proton collisions that LHC will hopefully start providing this fall is not granted, and while the scientific establishment is basically unanimous in claiming that those microscopical entities would anyway decay in a time so short that even top quarks look longevous in comparison, the hype about doomsday being unwittingly delivered by the hands of psychotic, megalomaniac CERN scientists continues unhindered.

Here are a few recent links on the matter (thanks to M.M. for pointing them out):

The source of the renewed fire appears to be a paper published on the arxiv a couple of weeks ago. In it, the authors (R. Casadio, S. Fabi, and B. Harms) discuss a very specific model (a warped brane-world scenario), in whose context microscopic black holes might have a chance to survive for a few seconds.

Never mind the fact that the authors say from the very abstract, as if feeling the impending danger of being strumentalized, “we argue against the possibility of catastrophic black hole growth at the LHC“. This is not the way it should be done: you cannot assume a very specific model, and then draw general conclusions, because others opposing your view may always use the same crooked logic and reverse the conclusions. However, I understand that the authors made a genuine effort to try and figure out what could be the phenomenology of microscopic black holes created in the scenario they considered.

The accretion of a black hole may occur via direct collision with matter and via gravitational interactions with it. For microscopic black holes, however, the latter (called Bondi accretion) is basically negligible. The authors compute the evolution of the mass of the BH as a function of time for different values of a critical mass parameter M_c, which depends on the model and is connected to the characteristic thickness of the brane. They explicitly make two examples: in the first, when M_c=100 kg,  a 10 TeV black hole, created with 5 TeV/c momentum, is shown to decay with a roughly exponential law, but with lifetime much longer -of the order of a picosecond- than that usually assumed for a micro-BH evaporating through Hawking radiation. In the second case, where M_c=10^6 kg, the maximum BH mass is reached at 3.5 \times 10^{21} kg after about one second. Even in this scenario, the capture radius of the object is very small, and the object decays with a lifetime of about 100 seconds. The authors also show that “there is a rather narrow range of parameters […] for which RS black holes produced at the LHC would grow before evaporating“.

In the figure on the right, the 10-base logarithm of the maximum distance traveled by the black hole (expressed in meters) is computed as a function of the 10-base logarithm of the critical mass (expressed in kilograms), for a black hole of 10 TeV mass produced by the LHC with a momentum of 5 TeV/c. As you can see, if the critical mass parameter is large enough, these things would be able to reach you in your bedroom. Scared ? Let’s read their conclusions then.

“[…] Indeed, in order for the black holes created at the LHC to grow at all, the critical mass should be M_c>10^5 kg. This value is rather close to the maximum compatible with experimental test of Newton’s law, that is M_c=10^6 kg (which we further relaxed to M_c=10^8 kg in our analysis). For smaller values of M_c, the black holes cannot accrete fast enough to overcome the decay rate. Furthermore , the larger M_c is taken to be, the longer a black hole takes to reach its maximum value and the less time it remains near its maximum value before exiting the Earth.

We conclude that, for the RS scenario and black holes decribed by the metric [6], the growth of black holes to catastrophic size does not seem possible. Nonetheless, it remains true that the expected decay times are much longer (and possibly >>1 sec) than is typically predicted by other models, as was first shown in [4]”.

Here are some random reactions I collected from the physics arxiv blog -no mention of the author’s names, since they do not deserve it:

  • This is starting to get me nervous.
  • Isn’t the LHC in Europe? As long as it doesn’t suck up the USA, I’m fine with it.
  • It is entirely possible that the obvious steps in scientific discovery may cause intelligent societies to destroy themselves. It would provide a clear resolution to the Fermi paradox.
  • I’m pro science and research, but I’m also pro caution when necessary.
  • That’s what I asked and CERN never replied. My question was: “Is it possible that some of these black might coalesce and form larger black holes? larger black holes would be more powerful than their predecessors and possibly aquire more mass and grow still larger.”
  • The questions is, whether these scientists are competent at all, if they haven’t made such analysis a WELL BEFORE the LHC project ever started.
  • I think this is bad. American officials should do something about this because if scientists do end up destroying the earth with a black hole it won’t matter that they were in Europe, America will get the blame. On the other hand, if we act now to be seen dealing as a responsible member of the international community, then, if the worst happens, we have a good chance of pinning it on the Jews.
  • The more disturbing fact about all this is the billions and billions being spent to satisfy the curiosity of a select group of scientists and philosophers. Whatever the results will yield little real-world benefit outside some incestuous lecture circuit.
  • “If events at the LHC swallow Switzerland, what are we going to do without wrist watches and chocolate?” Don’t worry, we’ll still have Russian watches. they’re much better, faster even.

It goes on, and on, and on. Boy, it is highly entertaining, but unfortunately, I fear this is taking a bad turn for Science. I tend to believe that on this particular issue, no discussion would be better than any discussion -it is like trying to argue with a fanatic about the reality of a statue of the Virgin weeping blood.

… So, why don’t we just shut up on this particular matter ?

Hmm, if I post this, I would be going against my own suggestion. Damned either way.

Comments

1. Seth Zenz - February 3, 2009

I actually think intelligent blogosphere discussion does a lot of good on this issue. For every invincibly ignorant commenter, I think there are a lot of people who are reassured, especially if time is taken to answer their individual questions. (Yes, even if we repeat ourselves.)

The problem is that the arXiv blog post was based on a complete misunderstanding of the LHC safety reports — i.e. the false belief that black hole decay was required to prove the LHC is safe. That, combined with the author’s effort to sensationalize and the apparent “officialness” of “the arXiv blog,” is what created the latest round of stupid media attention.

People will keep using this as a scare story as long as they can sell newspapers or get blog hits with it. Since it’s out there anyway, it’s up to physicists to remind everyone what nonsense it is.

And, just to remind everyone: the LHC is perfectly safe. To understand why, and to read what that conclusion is actually based on, you can go here: http://public.web.cern.ch/public/en/LHc/Safety-en.html

2. Daniel de França MTd2 - February 3, 2009

Why particle accelators and MRI instruments use Type I supeconductors instead of Type II?

3. Per - February 3, 2009

WATCH YOUR CHILDREN!!!🙂

4. Luboš Motl - February 3, 2009

They worry about Swiss chocolate but such a black hole could be very helpful for Swiss cheese which is famous for these holes. What would Switzerland be without such holes.

Left-wing people often believe that the Earth is gonna be fried etc. But I wondered why would sensible, i.e. right-wing people ever believe that the LHC is going to destroy the world.

Now I think that the answer is clear: the nice right-wing ordinary people see a lot of ugly, left-wing experimental scientists at CERN – so it’s not such a crazy idea to figure out that they might be going to destroy the world.😉

http://motls.blogspot.com/2009/01/lhc-black-holes-living-for-seconds.html

5. dorigo - February 3, 2009

Right lubos, and sorry for overlooking your post on the matter. As a matter of fact, the parenting has taken more a hit on my surfing than on my blogging😉

Cheers,
T.

6. dorigo - February 3, 2009

Seth, I appreciate your point of view. I have to agree. The fact is that it is so unforgiving to have to deal with the fanatics, that one forgets the good one does to people with all their wits still around them.

Daniel, I have no idea! Ask Chad Orzel, I am sure he knows.

Per, I am, but they are so darn well-behaved!

Cheers all,
T.

7. Daniel de França MTd2 - February 3, 2009

Chad told me he doesn’t really know. He said that, according to wikipedia, type I excludes mangnetic fields better. I’ve also seen that, but I don’t feel nice with that answer because It’s vague. He told me to ask Doug Natelson.

8. dorigo - February 3, 2009

LOL! THe whole blogosphere is being consulted to get around your question🙂

Now I’m curious, so please let me know what the answer is.
Cheers,
T.

9. Warren Platts - February 4, 2009

Well, um, if you actually take a close look at the inside of the paper instead of being satisfied with the conclusion in the abstract, you’ll see that Casadio et al.’s model assumes that mBH’s that don’t escape the planet altogether come “to rest”, at which point Bondi (gravitational) accretion is supposed to dominate, but since the gravitational event horizon is so much smaller than the size of an atom, atoms rarely get close enough to get sucked in by the mBH’s gravity.

However, there is no such thing as “rest” within the center of the Earth! The temperature is 7000 K; the density is 13,000 kg per cubic meter. And, after all, temperature is just an epiphenomenon of moving particles–remember? My back of the envelope calculations show that the Fe atoms at the Earth’s core vibrate with an average velocity of 2500 m/s. So really, we should write the “at rest” accretion rate as dM/dt = 4 * π * v * ρ * R^{2}. (Since the atoms are vibrating in all directions, we have to use the formula for the area of a sphere instead the cross section.) Thus 4 * 2.5 km/s = 10 km/s.

That is, the effective velocity that an mBH feels while at “rest” within the Earth’s core is equivalent to an mBH traveling at just less than the escape velocity of the Earth. In other words, the accretion rate does not decline with the mBH’s velocity with respect to the center of the Earth–contra Casadio et al. In that case, accretion always outpaces Hawking radiation, and there is net, long-term growth.

I convoluted the rate of accretion with the growth of the radius R as a function of mass. According to my calculations, an mBH could reach kilogram scales within one month.

So let’s hope Lubos is right, and that Casadio et al. totally screwed up the first part of their article to the tune of 20 orders of magnitude–because they sure as heck screwed up the last part of their paper!

10. Daniel de França MTd2 - February 4, 2009

Hi Tommaso, I copied here what Doug wrote (he authorized) to me:

——–
Hi Daniel –

I’ve asked Tommaso Dorigo and Chad Orzel the reason of why Type II superconductors are not used in MRI and particle accelators. I didn’t get a confindent answer, so, I’ve been redirected to you. Can you explain me?

Ummm, I’m virtually certain that you have this backwards. Type II
superconductors are exactly what’s used in both MRI and particle
accelerators, as far as I know. I have two superconducting magnets
in my lab, and they both use copper-clad NbTi wire, which is definitely
type II. The 800 MHz NMR system that my biochemist colleagues have uses
(I believe) Nb3Sn, which is another type II with even higher critical
current. Back in my undergrad days, I did some work on the prototype
magnets for the now-defunct SSC, and those were also based on NbTi.

All alloy superconductors are type II, and almost all elemental
superconductors (Nb being the exception) are type I.

Type II superconductors generally have much higher critical fields
(and critical currents at field) than type I. When the applied field
exceeds Hc1, vortices form in the type II materials that have normal
(nonsuperconducting) cores. The magnetic flux is contained in the
vortex cores. More field = more vortices. In the presence of a dc
current, an effective force is exerted on the vortices that acts to
push them transverse to both the field and the current. Motion of the
vortices leads to an EMF (and therefore heating) even without destroying
the superconducting state. Really good type II wires have been
engineered to have disorder (e.g. grain boundaries) that pins the
vortices in place. Eventually at high enough fields (> Hc2), the actual
superconducting state gets destroyed.

Now, as for why some materials are type I and others are type II,
I need to think hard about that. I can give you a semi-useless
answer (It’s all about the ratio of coherence length to magnetic
penetration depth. Small ratio, as in the high Tc compounds, =
type II. Large ratio, as in lead or tin, = type I.), but I don’t
have a good understanding of why that is the case.

Hope that helps,
Doug
——

Hi Doug,

Interesting. So, I thought that given that these instruments were cooled down by liquid helium, which is also the case of LHC magnets, they would also be of type I. I thought that if type II were sued, by “logical” extension, high temperarture superconductors would also be used.

The magnets used in LHC are indeed of type I:
http://en.wikipedia.org/wiki/Niobium-titanium

I guess my doubt was, why isn’t higth Tc used? You answered:
(It’s all about the ratio of coherence length to magnetic penetration depth. Small ratio, as in the high Tc compounds, = type II. Large ratio, as in lead or tin, = type I.)

So, now, my doubt is: Why I can’t see much talk into high Tc, at least for LHC or other particle accelators and MRI? LHC delays are mostly caused by the hazards of using extremely low temperatures and MRI costs by using extreme cooling.

Cheers,

Daniel

———
Hey –

The real practical problem with high Tc materials is that they’re
ceramics, so making actual wires out of them is extremely
difficult. Also, while the Tc is high in the cuprates, and
the critical fields are also high, the critical current densities
aren’t necessarily that wonderful. Conversely, NbTi is very
robust and pretty idiot-proof….

— DN

11. chris - February 4, 2009

“Left-wing people often believe that the Earth is gonna be fried etc. But I wondered why would sensible, i.e. right-wing people ever believe that the LHC is going to destroy the world.”

right lubos, the “sensible right wing people” rather believe that on doomsday jehova will come and fry the earth.

12. SaneScienceOrg - February 4, 2009

Man’s technology has exceeded his grasp. – ‘The World is not Enough’
(“I’m slightly irritated, because this non-story is symptomatic of a larger mistrust in science, particularly in the US, which includes things like intelligent design. Anyone who thinks the LHC will destroy the world is a twat.” Arrogant, deluded douchebag and CERN spokesmodel, Brian Cox.)
(September 24, 2008 – ‘LHC on hold until spring of 2009’ – PhysicsWorld.com: “The magnet failure last week at the Large Hadron Collider (LHC) means that the accelerator will not be up and running again until early spring of 2009, say officials at CERN. To keep the project on schedule, the team running the accelerator near Geneva have decided to skip a planned test run at an intermediate energy and re-start the LHC in 2009 at the full beam energy of 7 TeV.”) And begin creating Black Holes.
Zealous, jealous, Nobel Prize hungry Physicists are racing each other and stopping at nothing to try to find the supposed ‘Higgs Boson'(aka God) Particle, among others, and are risking nothing less than the annihilation of the Earth and all Life in endless experiments hoping to prove a theory when urgent tangible problems face the planet. The European Organization for Nuclear Research(CERN) Large Hadron Collider(LHC) is the world’s most powerful atom smasher that will soon be firing groups of billions of heavy subatomic particles at each other at nearly the speed of light to create Miniature Big Bangs producing Micro Black Holes, Strangelets, AntiMatter and other potentially cataclysmic phenomena as described below.
Particle physicists have run out of ideas and are at a dead end forcing them to take reckless chances with more and more powerful and costly machines to create new and never-seen-before, unstable and unknown matter while Astrophysicists, on the other hand, are advancing science and knowledge on a daily basis making new discoveries in these same areas by observing the universe, not experimenting with it and with your life. Einstein used Astronomy to prove his landmark general theory of relativity that, ironically, decribes, among other things, the Black Holes which the LHC is designed to produce at the hoped for rate of one per second.
The LHC is a dangerous gamble as CERN physicist Alvaro De Rújula in the BBC LHC documentary, ‘The Six Billion Dollar Experiment’, incredibly admits quote, “Will we find the Higgs particle at the LHC? That, of course, is the question. And the answer is, science is what we do when we don’t know what we’re doing.” And CERN spokesmodel Brian Cox follows with this stunning quote, “the LHC is certainly, by far, the biggest jump into the unknown.”
The CERN-LHC website Mainpage itself states: “There are many theories as to what will result from these collisions,…” Again, this is because they truly don’t know what’s going to happen. They are experimenting with forces they don’t understand to obtain results they can’t comprehend. If you think like most people do that ‘They must know what they’re doing’ you could not be more wrong. Some people think similarly about medical Dr.s but consider this by way of comparison and example from JAMA: “A recent Institute of Medicine report quoted rates estimating that medical errors kill between 44,000 and 98,000 people a year in US hospitals.” The second part of the CERN quote reads “…but what’s for sure is that a brave new world of physics will emerge from the new accelerator,…” A molecularly changed or Black Hole consumed Lifeless World? The end of the quote reads “…as knowledge in particle physics goes on to describe the workings of the Universe.” These experiments to date have so far produced infinitely more questions than answers but there isn’t a particle physicist alive who wouldn’t gladly trade his life to glimpse the “God particle”, and sacrifice the rest of us with him. Reason and common sense will tell you that the risks far outweigh any potential(as CERN physicists themselves say) benefits.
This quote from National Geographic, “The hunt for the God particle”, exactly sums this “science” up: “If all goes right, matter will be transformed by the violent collisions into wads of energy, which will in turn condense back into various intriguing types of particles, some of them never seen before. That’s the essence of experimental particle physics: “You smash stuff together and see what other stuff comes out.” Read about the “other stuff” below;
http://www.SaneScience.org
http://www.risk-evaluation-forum.org/anon6.htm
http://www.LHCFacts.org/
http://www.LHCDefense.org/
http://www.LHCConcerns.com/
Popular Mechanics – “World’s Biggest Science Project Aims to Unlock ‘God Particle'” – http://www.popularmechanics.com/science/extreme_machines/4216588.html

13. Luboš Motl - February 4, 2009

Well, it’s still much more reasonable to believe that Jehovah will fry the Earth than to believe that man-made carbon dioxide will do the job – it’s about the order of magnitude estimates and Jevovah is simply closer to the correct estimate.😉

14. Bos'n Higgs - February 5, 2009

Perhaps I may impose upon Mr. Dorigo’s time to ask a specific question about

arXiv:0806.3381v2 (“Astrophysical implications of hypothetical stable TeV-scale black holes”; Giddings, Michelangelo, Mangano)

On page 25, equation 4.49 gives a value in years for the case of D=6. This equation, as we see, starts with 9.7 x 10^4, and continues with items that are difficult to type in this message box.

The authors’ comment, immediately following on page 26, is “The D = 6 time is short as compared to geologic time scales.” What is the D=6 result, please? What value – or range of values – goes in the place of

“1 over (lambda 6,4)” ?

What value goes in the place of

“(M sub D / M sub 0)^2” ?

A second question about M sub D, please. Judging from where they say, on page 26 …

“we obtain in D = 7 a combined time scale of approximately (6.4,20,40,65,94) billion years for M sub D = 1,…,5TeV”

… (M sub D / M sub 0) appears to be a ratio of masses as expressed in energy-equivalent TeV. Would an M sub D equal to 14 be the same thing they are writing about on page 9:

“the maximum value of M = 14 TeV allowed at the LHC”

… i.e., is one’s guideline: “In working with values of M sub D, don’t bother using a value higher than 14” ?

Thank you for your time.

15. dorigo - February 5, 2009

Boson,

I unfortunately am not qualified to answer your questions in the detailed manner it would deserve. However, I suggest you to contact the authors directly. You might be surprised by their willingness to clarify your doubts. Both authors have cern.ch email domains (just firstname.lastname at…)

Good luck,
T.

16. Yatima - February 6, 2009

And this discussion is clearly relevant because, of course, the evidence that we are living in a “warped brane-world” (whatever that is) is extremely overwhelming.

*Facepalms*

Of course, we can assume still more interesting beasts than bog-standard black holes on branes, what about ..uh.. David Brin’s Earth-eating “Knotted String” for example? Gentlemen, to your blogs!

17. dorigo - February 6, 2009

Lol Yatima… Of course the evidence is there for everybody to see.

See, that is what I meant above when I said “This is not the way it should be done: you cannot assume a very specific model, and then draw general conclusions”… Unfortunately, for the sake of arguing the pretext is sufficient.

Cheers,
T.

18. Warren Platts - February 6, 2009

Hi Paul,

I must retract my calculation above, as it was based on a typographical error on page 1 of Casadio et al. (M5=Mew s/b 10^{-24}) that threw my calculation off by 5 orders of magnitude, so it would take at least 10,000 years to grow to 1 kg–assuming no Hawking radiation. If you wanted delete the above post (and this one), that would be fine with me.

19. Daniel de França MTd2 - February 7, 2009

Hi Tommaso,

What kind of arguments would you say to black hole alarmists if LHC worked above 1000TeV, or anything that would give a much greater $s^{1/2)$ than any high energy cosmic rays?

20. dorigo - February 7, 2009

I would simply point out that black hole production happens if the scale of quantum gravity is below the energy achievable, and if this hasn’t happened at E=500 TeV, admitting it happens at 1000 TeV is a real rare chance, even giving the scale a flat prior from 0 to 10^18 GeV.

Cheers,
T.


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