With excitement building about an announcement due tomorrow from scientists working at the Large Hadron Collider, today’s Lindau Nobel Laureate Meeting talks kicked off with the Higgs, explored some mysterious anomalies with neutrinos and looked forward to some practical applications of spintronics coming soon in information and communication technologies. (You can read all our coverage this week, including the “30 under 30” profiles series of young scientists attending, in this In-Depth Report. Also see the Lindau Nobel Community blogs.)
Martinus J.G. Veltman, who won a Nobel in 1999 for his work on the quantum structure of electroweak interactions in physics, expressed near regret about the idea that the Higgs boson, the missing particle necessary for completion of the Standard Model of particle physics, may soon at last be announced. “What does it mean if they discover the Higgs at the LHC?” he asked. “First of all, it completes the Standard Model.” In effect, however, “That closes a door,” he said, meaning that it is not clear what new experiments along those lines could immediately follow. “Discovery of the Higgs is sort of a bad thing.” Finding the Higgs would not resolve all the questions of physics, of course. One that vexes Veltman is why, in particular, particles come in three generations, defined by an intrinsic property called spin. “Supersymmetry has promise of explaining why there are three generations but it has never fulfilled that promise” so far, he said. “This problem, I consider to be, more strange, further out, than the Higgs particle.”
“The most appealing to me of the new physics envisioned is supersymmetry,” agreed David Gross, who shared a 2004 Nobel for the discovery of asymptotic freedom in the theory of the strong interaction, and who serves as an adviser for Scientific American. Some questions around supersymmetry might be able to be tested at LHC.
Carlo Rubbia, who won in 1984, for contributions to W and Z particles discovery, turned to a different puzzle: anomalous neutrino readings at reactors.
“Neutrino masses and oscillations represent a main experimental evidence of physics beyond the standard model,” Rubbia said. Evidence may be building up from several experiments in the search for a hypothetical type called sterile neutrinos. They won’t interact except with gravity, making them very difficult to detect. If they are heavy enough, they may contribute to cold dark matter or warm dark matter. “Maybe something is there,” said Rubbia of the experimental results that show “missing” neutrinos—possibly the sterile neutrinos. “It’s certainly a big question mark, which we have to understand better.” Better experimental equipment being brought to bear could provide the answer. Rubbia said 114 institutions were working on the problem in one way or another. “There is a real revolution in the sterile neutrino experiments,” he said, an effort that is “on the order of an LHC-type experiment.”
Albert Fert, who shared the 2007 Nobel Prize for the discovery of giant magnetoresistance, used in computer hard drives, discussed advances in spintronics, a type of electronics that uses not just the electrical charge of electrons but also a quantum property called spin, which lets electrons act like tiny bar magnets. Beyond today’s M-RAM (magnetic RAM), based on giant magnetoresistance, said Fert, the next generation for memory, will be STT-RAM (STT stands for spin-transfer torque), where spin alone is used to effect changes in magnetic memory layers. STT-RAM could be in products in one or two years, said Fert, who also says that hybrid structures that combine semiconductors and spintronics could be a first step beyond today’s CMOS flash memory.
Last, William D. Phillips, who shared a 1997 Nobel for work in using lasers to cool and trap atoms, talked about recent work in creating artificial magnetic fields that can act on ultracold neutral atoms by using a pair of lasers directed at rubidium atoms. Using such artificial magnetic fields to create simulations could help probe questions about the quantum phases of matter, “one of the as-yet-unknowns mentioned by David Gross this morning,” Phillips said. “Some of the problems in quantum mechanics are easy to state and impossible to calculate, at least with any computers that we have today,” said Phillips. “One of the answers to that problem is to let nature do the calculation [using ultracold atoms] and measure the answer.”