Re: Dangerous Ion Colliding Experiment?

[Gordon Smith <slipstk@OLEMISS.EDU>]

At 03:55 PM 7/23/99 -0500, you wrote:
>A student approached me after class today to see if I knew about an
ion
>colliding experiment that was supposed to begin today but was
cancelled
>due to a chance of generating a tiny black hole or strange
matter.  Does
>anybody know anything about this experiment and/or rumor?

I think your student is referring to the letters section of the July
Scientific American, in which there is a letter regarding something
covered in a prior issue.  The letter seemed to be ranting about the
possibility of destroying the earth through high energy physics.  To
quote from the SciAm web page:

Madhusree Mukerjee's article on the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory ["A Little Big Bang," March] alarmed several readers, such as Michael Cogill of Coquitlam, B.C. "I am concerned that physicists are boldly going where it may be unsafe to go," writes Cogill, who worries that creating stuff that has not to anyone's knowledge existed since the early universe“namely, a quark-gluon plasma“could result in a catastrophe. "What if they somehow alter the underlying nature of things such that it cannot be restored?" he asks. Another reader wondered whether the RHIC experiments could result in miniature black holes (below).

BLACK HOLES AT BROOKHAVEN?

Thank you for the article by Madhusree Mukerjee entitled "A Little
Big Bang" [March]. In the 1970s
Stephen W.
Hawking postulated that in the early
moments of the big bang, miniature black holes would have been present.
Although they no longer exist in our region of the universe, such mini
black holes could be created by smashing a proton into an antiproton with
enough energy. If one were created near a large congregation of mass and
if it started absorbing that mass before exploding, the black hole could
reach a relatively stable half-life and thus continue to grow. If this
happened on the earth, the mini black hole would be drawn by gravity
toward the center of the planet, absorbing matter along the way and
devouring the entire planet within minutes. 
My calculations indicate that the Brookhaven collider does not obtain
sufficient energies to produce a mini black hole; however, my
calculations might be wrong. The only way to determine the energy density
at which a mini black hole would be created as an intermediary step to
the type of explosion depicted in your article is to build a collider and
do the experiment. Is the Brookhaven collider for certain below the
threshold? 
WALTER L. WAGNER
via e-mail 

Frank Wilczek of the Institute for
Advanced Study in Princeton, N.J.,
replies: 
Whenever we explore new physical (or chemical, or biological) phenomena,
questions like Cogill's arise regarding whether we might unwittingly
trigger some catastrophe. For example, in the early days of the
Manhattan
Project,
Fermi
and others carefully considered whether a nuclear explosion might ignite
the atmosphere. Scientists must take such possibilities very
seriously--even if the risks seem remote--because an error might have
devastating consequences. In the case of the Brookhaven RHIC, dangerous
surprises seem extremely unlikely. First, nuclear collisions with larger
energies take place regularly as cosmic rays rain down on our
atmosphere“so if a disaster were possible, it would have already
occurred. Second, related regimes have been explored in detail, and so we
have substantial evidence that our theoretical framework for
understanding what will happen is reliable. Although we cannot calculate
the consequences in complete detail, we can distinguish credible from
incredible scenarios. 
The idea that mini black holes will be formed, as Wagner suggests,
definitely falls in the latter category. The energy densities and volumes
that will be produced at RHIC are nowhere near large enough to produce
strong gravitational fields. On the other hand, there is a speculative
but quite respectable possibility that subatomic chunks of a new stable
form of matter called strangelets might be produced (this would be an
extraordinary discovery). One might be concerned about an
"ice-9"-type transition, wherein a strangelet grows by
incorporating and transforming the ordinary matter in its surroundings.
But strangelets, if they exist at all, are not aggressive, and they will
start out very, very small. So here again a doomsday scenario is not
plausible.

-G-

-----------------------------------------

Gordon Smith

National Center for Physical Acoustics

Coliseum Drive

University, MS 38655

slipstk@olemiss.edu