Black holes at RHIC?

A statement from RHIC theoretical nuclear physicist Dmitri Kharzeev:

Horatiu Nastase, a member of the high-energy physics theory group at Brown University, has written a paper, posted on the preprint website arxiv.org, in which he claims that collisions at Brookhaven’s Relativistic Heavy Ion Collider (RHIC) produce the analog of a black hole.

Horatiu is referring to a mathematical similarity between the physics of the real world, which govern RHIC collisions, and the physics that scientists use to describe a theoretical, “imaginary” black hole in a hypothetical world with a different number of space-time dimensions (more than the four dimensions — three space directions and time — that exist in our world). That is, the two situations require similar mathematical wrangling to analyze. This imaginary, mathematical black hole that Horatiu compares to the RHIC fireball is completely different from a black hole in the real universe; in particular, it cannot grow by gobbling up matter. In other words, and because the amount of matter created at RHIC is so tiny, RHIC does not, and cannot possibly, produce a true, star-swallowing black hole.

This does not mean, however, that RHIC cannot study some of the phenomena that happen in the vicinity of black holes, as explained in a paper we wrote with Kirill Tuchin, also of Brookhaven's theoretical nuclear physics group. The explanation for this begins with Einstein’s “Equivalence Principle,” which states that gravity and acceleration (or deceleration) are actually equivalent forces. The principle explains why a person going up in an elevator feels slightly heavier, just as they would if gravity on Earth were stronger.

In the same way, the rapid deceleration of RHIC ions as they smash into each other for a very short period of time (about 10^(-23) second) is similar to the extreme gravitational environment in the vicinity of a black hole. This means that RHIC collisions should emit a bunch of thermal particles similar to the “Hawking radiation” emitted by a black hole. Since Hawking radiation is the cause of black hole decay, not formation, its existence would be yet another reason that RHIC cannot produce a real gravitational black hole.

For more information on this, see additional discussion from Kharzeev and a Quantum Diaries blog entry from RHIC physicist Peter Steinberg. See also: Statement on Committee Review of Speculative "Disaster Scenarios" at Brookhaven Lab's RHIC, October, 1999

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