Concern Over Creating Black Holes

Maria Williams writes to tell us about worry surrounding the impending startup of CERN's Large Hadron Collider. Some fear that the device, in creating mini black holes, could jeopardize Life As We Know It. While the tiny black holes should evaporate quickly — throwing off so-called Hawking radiation that can be detected — CERN software developer Ran Livneh reminds us that "Any physicist will tell you that there is no way to prove that generated black holes will decay." The LHC site assures us there's nothing to worry about. The flap is reminiscent of the time the Relativistic Heavy Ion Collider went live. The worry then was that "negative strangelets" could gobble up the world.

Comments

SETI paradox resolved

[Gary W. Longsine]

Where are they? Gone.

Civilizations routinely destroy their home planet by creating miniature black holes thereupon whilst trying to figure out what makes them tick. Technology advances faster than democracy, and it has never yet in the long history of the universe been put to a vote.

Natural Particle Accelerators

[noretsa]

If it were really so easy to destroy the world it would have happened long ago.

For example, there are as yet little-understood phenomena that can accelerate particles six orders of magnitude faster than anything achievable in a lab. Try reading about Ultra-high-energy cosmic rays.

More specifically read the story of the Oh-My-God Particle. This was a proton detected in October of 1991 that had an energy of 3.2 * 10^20 eV. The equivalent energy of a baseball thrown at 55 mph... all in a single proton travelling at 99.99999999999999999999951% the speed of light!

While something travelling that fast has little probability of interacting with anything you could imagine the surprise if one of those hit you! I think that the fact we are alive with such powerful forces already at work in our universe means we have little to fear.

Utter Crap

[bockelboy]

I work one of the LHC expirements (low-level grad student, no one important), and this is utter crap.

Yes, there are physicists who are concerned. There is a chance that this could happen - one of those "if everything we know about high energy physics is completely wrong, this could happen". There is an approximately equal chance that Pat Buchanan will be nominated as the Democrat candidate for president in 2008. No physicist can prove that this won't happen - just like no physicist can actually prove that Superman doesn't exist.

Unfortunately, it's about the only way a reporter can "sexy up" a story about a particle accelerator. I can't wait to see the headlines in 2007 - "Will the Earth end tomorrow?" (subheading: "Respectable scientists say 'No'").

Nature itself tells us: no doomsday

[xPsi]

IAAP (who worked on RHIC physics). The same arguments used in 1999-2000 with RHIC (and with Fermilab before that) should be used here. There is no chance for doomsday catastrophe. While these events at the LHC are "high energy" from a human technology point of view (per event per particle), the LHC generates low energy events at low rates compared to nature itself. There are millions of LHC-like events (or "greater") per second that occur on the surface of the moon alone, not to mention in our own atmosphere from cosmic rays. While cosmic rays are carefully studied, the reason we build machines such as RHIC, Fermilab, and LHC is, as scientists, we like to study events systematically and carefully at specific energies in a relatively low-noise environment (difficult to do with cosmic rays, which is why we might not formally detect strangelets or black holes in such events when measured). However, if there were problems with voracious black holes, stranglets, or other doomsday scenarios due to elementary particle collisions, they would have happened long, long ago in nature (locally) -- we would have seen evidence for it on the moon, atmosphere, etc. (assuming we survived long enough to witness it with such a high event rate - it probably would have happened long before we had a chance to even evolve).

See Doomsday Fears at RHIC in particular the reference Review of Speculative "Disaster Scenarios" at RHIC

You are correct

[jd]

The size of the singularity is fixed, but the size of the black hole is not. The size of the black hole is directly proportional to the mass and should be a function of the entropy. Hawking radiation is the stream of particles of quantum foam which switch from being virtual to being real when the opposite particle is captured by the black hole. For reasons I do not entirely understand, it is assumed that the majority of particles captured will be the anti-particle, thus adding a negative amount of mass to the black hole. The companion particle will then be observed as radiation that appears to come from the vicinity of the black hole.

There is an assumption in all of this, that the singularity is a point in space/time. This is how it is normally considered, but it is by no means the only interpretation that would be valid. Evaporation only applies within this assumption because entropy can only ever increase and the entropy of a physical point singularity that did not evaporate would be a constant. If a singularity does not exist as a point (there are other solutions, such as a "Kerr Ring Singularity") or doesn't actually exist as a physical entity at all (see below for a trivial theory where that would work), then all bets are off.

This is a "just for amusement" theory, for the sole purpose of illustrating a singularity that would not violate the second law of thermodynamics and still not evaporate. Let us say that a singularity does have infinite gravity at the point at which it "exists", and that the curvature of space/time is a direct function of gravity, then what we call a singularity would not actually exist as an object. At all. What you would have is a "well" of essentially zero diameter where the sides were orthogonal to space and along the axis of time in a negative direction. The notion that "space and time end at a singularity" would not be true to an observer within the Universe, as they would not experience the well as anything other than a continuation of space. However, space would then not be simply-connected and it would be mathematically possible to show that there were mathematically definable points within an otherwise well-defined region that could not be reached.

Now for the well itself. It cannot stop within the universe, because there are no forces along that axis. F=ma, so if F=0, then a=0. Nor can it continue forever, because it's going along the axis of time and time does not continue forever. There is exactly one place such a well could terminate, that being the moment of the Big Bang. (It stops there because there's nothing more to travel along.) It would be an express trip, there would be no possibility of getting off anywhere else. So it's just as well that, if this correct, anything that fell in would be crushed into quantum foam. Nothing else is going to fit in a well of zero diameter. Hawking's theory of imaginary time becoming real time would certainly fit this description.

This theory would require that (a) black holes can only ever expand, (b) hawking radiation would contain equal numbers of particles and anti-particles (which would explain why we have such trouble finding any), (c) the recently-proved Poincare hypothesis does NOT apply to space/time, as it is no longer simply-connected, and therefore the Universe is NOT topologically equivalent to a hypersphere (which is going to upset the Chinese and Russians no end), and (d) the Hubble constant absolutely must be below 1.

(That last one might not be obvious, so I'll explain. This theory recycles matter and energy through time to the big bang. Since you have a Universe's worth of matter/energy, you would not need inflation theory - which is "good" because inflation is an ugly hack whose chief benefit is that it works vastly better than every other mainstream theory in existance. But you can't guarantee that the whole Universe is recycled if the Universe is open. You can only guarantee 100% recycling if every possible photon and every possible particle is absolutely