Black Holes - Interview with Dr. Steve Giddings

n this Special Topics interview, Dr. Steve Giddings of the University of California, Santa Barbara (UCSB) talks about his highly cited work in black holes research. Dr. Giddings is the lead author of the top-ranked paper published in the past two years on this topic, "High energy colliders as black hole factories: The end of short distance physics" (Physical Review D 6505: 6010, 2002), which has been cited a total of 74 times. He is also a coauthor on the paper ranked at #12 on this same list, "Classical black hole production in high-energy colliders" (Physical Review D 6604: 4011, 2002), with 12 total cites. Dr. Giddings is a Professor of Physics at UCSB. He is also an enthusiastic alpinist.

Why do you think your paper is highly cited?

There has been a lot of interest in the possibility that the fundamental scale of gravity, the Planck scale, could be in the vicinity of a TeV, the energy scale accessible by the Large Hadron Collider (LHC), presently under construction near Geneva. This idea is linked with the notion that there would be extra dimensions of space that might also be relatively large and experimentally observable.

If we discover the Planck scale near the TeV scale, this will represent the most profound discovery in physics in a century, and black hole production will be the most spectacular evidence of that new discovery.

If this possibility is true, the most remarkable prediction of this scenario is that black holes could be created at high-energy accelerators, perhaps as early as with the LHC. We studied this problem of black hole creation and decay carefully, and came to the conclusion that there could be a lot of black holes made (up to around one per second) and that they could apparently produce very outstanding effects in the detectors at the LHC. This possibility has obviously aroused a lot of interest.

What are the circumstances which led you to your work?

Stephen Hawking's prediction that black holes evaporate (which would be experimentally verified in this scenario) leads to a seemingly deep paradox regarding what happens to information cast into a black hole. I've invested a lot of thought into this paradox, and the related problem of black hole production in high energy collisions, over the years. When it was suggested that the Planck scale could be as low as a TeV, the game clearly changed—now we could imagine experimentally addressing these questions. This much was obvious (as was reiterated by Banks and Fischler), but less clear was how many black holes you would produce and what their creation and decay would look like. I'd written a bit about these ideas in earlier work, e.g. with E. Katz, but for reasons incomprehensible in hindsight really wanted to first better understand TeV-scale gravity scenarios in string theory. After doing that work Kachru and Polchinski, I approached Scott Thomas with the suggestion that we work out the black hole creation and evaporation story. The more we learned, the more excited we became. (After we'd gotten some of our results, we also heard that another team—Dimopoulos and Landsberg—was working on the same problem; their paper became public a little while after ours.)

Would you describe the significance of this work for your field?

If we discover the Planck scale near the TeV scale, this will represent the most profound discovery in physics in a century, and black hole production will be the most spectacular evidence of that new discovery. We will finally be able to gain clues about the possible breakdown of space and time, we will likely discover extra dimensions, and we might experimentally verify some of the predictions of string theory. Finally, black hole production would apparently represent the end of our quest to explore ever shorter distances, by performing collisions at higher and higher energies. Once you see black holes, you stop seeing shorter-distance physics; in some sense shorter distances likely don't exist. You've apparently reached a fundamental limit.

Where has this research gone since the publication of your paper? Where do you see it going 10 years from now?

There have been a lot of people who have looked at other consequences of TeV-scale black hole production, and worked out some more of the details of the process and what we'd see at the LHC. We received some questions about whether black holes could really form this way, which were subsequently addressed in more precise calculations, particularly with Eardley. In unpublished work, and in other people's work, the possibility has also been explored that black holes could be created by cosmic rays striking the upper atmosphere.

Where it goes 10 years from now depends a lot on what we find at the LHC. If we find black holes, they will furnish the generic description of high-energy physics. If we find evidence that the Planck scale is up closer to 10^19 GeV, it will become a much more academic subject. And if we don't reach the Planck scale at the LHC but do find hints that the Planck scale is a little higher, this could be the major impetus for building another larger accelerator.

What lessons would you draw from your work to share with the next generation of researchers?

Believe in your ideas, push them as far as you can, and don't get distracted. On a more scientific note: don't believe we've figured out all the possibilities for the physics at the TeV scale until we actually explore that scale experimentally—or come up with new ideas about it!

Steve Giddings, Ph.D.
University of California, Santa Barbara
Santa Barbara, CA, USA

with Stephen Hawking
with Savas Dimopoulos

ESI Special Topics, July 2004
Citing URL - http://www.esi-topics.com/blackholes/interviews/SteveGiddings.html