Science Club: Robert Oerter
In which DCist interviews area scientists, researchers, and academics on topics pertaining to natural and scientific interests. As Thomas Dolby would say: science!
Robert Oerter has taught at the University of Maryland, Howard University, and George Mason University, where he has worked for the past 10 years. He is the author of The Theory of Almost Everything: The Standard Model, The Unsung Triumph of Modern Physics (Plume Press), which has been translated into Italian and Spanish. Dr. Oerter has done research in elementary particle physics, supersymmetry, quantum chaos, and underwater acoustics.
DCist: Protons and neutrons are both hadrons. Are there other hadrons?
Robert Oerter: A hadron is any particle built of quarks. There are six different types of quark, and six corresponding anti-quarks, so there are many possible combinations. Protons and neutrons are both baryons: particles built of three quarks. Mesons are built of one quark and one anti-quark.
DCist: The Large Hadron Collider is a 17-mile loop of tunnels. What explains its large scale?
RO: You want to achieve the highest possible energy, but the protons lose energy as they go around the bend of the accelerator. So you want to have as little bend as possible: that means as large a loop as possible.
DCist: How can a particle that results from the collision of two protons be more massive than a proton?
RO: The secret is Einstein’s famous E = mc2. According to Einstein, energy can be transformed into matter (and vice versa). When you accelerate the protons to nearly the speed of light, they carry a tremendous amount of energy. That energy can be transformed into particles with an equivalent amount of mass.
DCist: What is the difference between a miniature black hole and a black hole? Are they both singularities occupying single points in space?
RO: Both are singularities, as you say. Miniature black holes are . . . smaller. Really. That’s the only difference.
DCist: Do scientists expect miniature black holes to emit Hawking radiation?
RO: Yes. Because they are so small, they radiate very quickly and evaporate in a tiny fraction of a second.
DCist: What would constitute evidence for the Higgs boson (the theoretical particle that gives mass to matter)?
RO: The basic idea is that, when the energy of your proton beam gets close to the energy needed to create a new particle, the collision rate increases. So you ramp up the beam energy, and look for jumps in the collision rate. In practice, things are much more complicated than that. The LHC will have so many collisions (a billion every second) that it won’t even record most of them — the computer software will automatically throw them out. Even among the collisions that are kept, most will be uninteresting “background.” So the experimenters will need to sort through everything carefully to pick out the events that are possible Higgs events.
DCist: What would constitute evidence for extra dimensions beyond the three (okay, plus time) that we know?
RO: This one is even harder to answer. One possibility is that energy would be carried away into the extra dimensions — to us it would look like an undetected particle was produced. But how would we know the undetected particle really is an indication of higher dimensions, rather than a more garden-variety new particle? My gut feeling is that extra dimensions will be very hard to prove.
DCist: If we witnessed evidence of dark matter or dark energy after an LHC collision, would we necessarily know it?
RO: That’s a very good question. Dark matter is proposed to explain certain astronomical observations: galaxies seem to have much more mass than can be accounted for by the normal stars, planets, etc. that they contain. Now, there are many speculative theories out there that provide particles that are dark matter candidates. If a particle was produced at LHC that fits with one of these theories, we still wouldn’t know for sure if that particular particle is the one responsible for the astronomical observations we ascribe to dark matter. So, no, we wouldn’t necessarily know. Still, a good case could be made if the new particle had all the right properties.
Dark energy is a different story. It is unlikely that LHC will shed any light on dark energy.
DCist: Has public interest in (or fear about) the LHC revived interest in the Superconducting Super Collider once planned for Waxahachie, Texas? Were there things that the SSC can do that the LHC cannot?
RO: Not as far as I am aware. The SSC would have been able to reach even higher energies than LHC, and so could potentially have discovered more new particles. Fortunately, there are good reasons to believe that the LHC will be powerful enough to produce the Higgs particle. But other interesting physics (like the dark matter candidate particles) could be beyond its reach.
Attention has turned to other proposed colliders, like the International Linear Collider.
DCist: If the LHC were to start a reaction that caused the entire universe to be engulfed in strange quark matter, whom could we blame?
RO: No one, because no one would be around to blame. But you knew that already.
Photo by Image Editor.