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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.

Black holes, the winged seeds of our Universe January 8, 2009

Posted by dorigo in astronomy, cosmology, news, science.
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From Percy Bysshe Shelley’s “Ode to the West Wind” (1819), one of my favourite poems:

[…]O thou,
Who chariotest to their dark wintry bed
The winged seeds, where they lie cold and low,
Each like a corpse within its grave, until
Thine azure sister of the Spring shall blow
Her clarion o’er the dreaming earth, and fill
(Driving sweet buds like flocks to feed in air)
With living hues and odors plain and hill:
Wild Spirit, which art moving everywhere;
Destroyer and preserver; hear, oh, hear!

The winged seeds -of galaxies, and ultimately of everything that there is to see in our Universe- appear today to be black holes: this is what emerges from the studies of Chris Carilli, of the National Radio Astronomy Observatory (NRAO). In a press release of January 6th, Carilli explains that the evidence that black holes are antecedent to galaxy formation is piling up.

In a nutshell, there appears to be a constant ratio between the mass of objects like galaxies and giant globular clusters and the black hole they contain at their center. This has been known for a while -I learned it at a intriguing talk by Al Stebbins at the “Outstanding Questions in Cosmology” conference, in March 2007 at the Imperial College of London. But what has been discovered more recently is that the very oldest objects contain more massive black holes than expected, a sign that black holes started growing earlier than their surroundings.

This is incredibly interesting, and I confess I had always suspected it, when looking at the beautiful spiral galaxies, attracted in a giant vortex by their massive center. I think this realization is a true gate to a deeper understanding of our Universe and its formation. A thought today goes to Louise, who has always held that black holes have a special role in the formation of our Universe.

Interviewed for Nature (the magazine…) September 10, 2008

Posted by dorigo in internet, news, personal, physics, science.
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Yesterday I had lunch at the Meyrinoise (courtesy Nature) with Geoff Brumfiel, a reporter from Nature (the magazine, not the bitch) who came to CERN to witness the big media event of today. We talked about several things, but in the end what was left to discuss for the podcast we recorded was the least interesting thing of all -the fact that we are not going to disappear in a black hole after LHC will eventually start colliding beams operation (which, for the absent-minded among you, hasn’t happened yet -only a beam at a time has been circulated in the machine so far).

In any case, you can hear some more interesting interviews along with mine at the Nature site, specifically here.

UPDATE: fixed the link to the main page of Nature news. There, you find my pic (not a good one actually) linking to the interviews.

UPDATE: Hmm, if Nature (the magazine AND a little bit of a bitch today) keeps changing the address of pages I link, I am going to download the darn site here and stop worrying. Anyway, here is the updated link to the LHC special.

Strasbourg clears the last hurdle to LHC September 1, 2008

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The European Court of Human Rights in Strasbourg has rejected today the appeal by a group of doomsday-scenario aficionados led by Markus Goritschnig, who claimed the experiment violated Article 2 and Article 8 of the European Convention for Human Rights, which grants the right to live and the right to the respect of human and family life, respectively.

I am so fed up with such claims, soooo fed up, that a small but non negligible part of me is actually rooting for black holes being actually produced by LHC, for Hawking radiation being a gross mistake, and for the very first black hole created at LHC startup to swallow our whole solar system. It would be a reasonable punishment for the opposers of the LHC if, after losing all their battles, they were finally torn to smithereens by a black hole. Of course, the fact that the rest of us would also have to die the same horrible death is a small price to pay for being direct observers of such a sublime punishment – death by the very device they claimed to fear, because their claim was groundless, despite being true.

More math illiteracy September 1, 2008

Posted by dorigo in internet, news, physics, science.
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In my previous post I complained about the utter inability of many italian reporters to pay attention to numerical figures in their pieces, as if the hard data they sometimes have to unwillingly report was a nuisance.

Today, upon reading the news on the site of the other main italian newspaper, Repubblica, I saw another example of that effect. And it is an even more annoying one, for several reasons. First, because Repubblica is the newspaper I prefer among the two. Second, because it appears in a science-related piece, written by a reporter who is supposed to pay attention to the data he produces. Third, because it concerns the LHC.

In a piece titled “Fermate il test sul Big Bang o la Terra sparirà” (Stop the Big Bang test or Earth will vanish) Enrico Franceschini wrote a rather sloppy account of the issue of micro-black-hole production by the LHC. For instance, sloppiness is apparent when he writes:

“…ci sono scarse possibilità che l’acceleratore formi un buco nero capace di porre una minaccia concreta al pianeta…”

(there are slim chances that the accelerator creates a black hole capable of posing a concrete threat to the planet)

Slim chances… Oh well. I am rather more pissed by the following statement:

“Vero è che il nuovo acceleratore ha suscitato attenzioni e polemiche perché è il più grande mai costruito, con una circonferenza di 26 chilometri e la possibilità di lanciare particelle atomiche 11.245 volte al secondo prima di farle scontrare una contro l’altra a una temperatura 100mila volte più alta di quella che esiste al centro del sole.”

(.…the possibility to launch atomic particles 11,245 times a second before having them collide one against the other at a temperature 100 thousand times higher than the one existing at the center of the sun.)

Atomic particles ? Was “protons and heavy ions” too technical for the piece ? And where the hell is that 11,245 Hz figure coming from ? “Launching atomic particles 11,245 times a second” does not even make any sense. The right figure, however, is 40 million times a second. This time the mistake is by 3.55 orders of magnitude. Darn, the explanation suggested in the thread of the previous post does not even apply here.

What the micro black hole fear mongering really is about June 12, 2008

Posted by dorigo in personal, physics, science.
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I was slightly surprised this morning to read the following comment from my friend Kea, after I had answered in slightly provocative terms to the umpteenth comment of some anti-LHC activist promoting the modern-day equivalent of a raid with torches:

Tommaso, to be honest, I am a bit tired of this LHC-safety-case bashing. Even given all the usual reasonable arguments, how sure are you that you have accounted for all your hidden assumptions? I’m a theorist, and the only I thing I know for sure is that NOBODY knows what we’ll see at the LHC.

I wish to paste here my answer to Kea, because I think the heart of the matter must not be mistaken.

I am of course unable to be sure of what the LHC will produce, if black holes or red dragons. But I am sure that the advancement of science calls for boldness in opening doors leading into the unknown. And I am in favor of the small risks the package includes. The question, to me, is not whether the risk is zero or tiny. It is whether we must insist for rationality in our choices or be led by hysteria. And I have my own answer. Therefore I will, sorry, insist in bashing these clowns whenever they pester this site with their oddities.

Now, I am sure Kea agrees with my statement. I think she just wants to communicate that we might end up feigning more confidence than we really possess. After all, it is not so uncommon to find fanatics among scientists too: we are humans. Granted: but fear mongering is to be addressed before we clean up our own home.

UPDATE: on a second thought, there is nothing wrong in principle with raising objections about the LHC or whatever other scientific endeavour, if done respectfully. And following Voltaire, I have to remind myself that I defend the right to speak of those who disagree with me. So I have to offer a partial retractatio: I will not “bash those clowns” as they “pester this site with their oddities”, but rather counter their arguments with rationality. Not forgetting that I want to have my share of fun as I do it 😉