Nobel Physics Laureates (day 4)

On the cycle down to the Inselhalle today (where the conference is on), Martin told me that when his German supervisor was young, he attended the same conference we are attending 50 years ago. Only a slight difference, there was only 100 German students (compared to 550 internationals now) and the Nobel Laureates at the time who attended included greats like Albert Einstein, Werner Heisenberg, Wolfgang Pauli, and Neils Bohr. If you have ever done any bit of Physics, you would have heard at least one of these names. It’s fascinating to think we’re literally walking in the footsteps of greatness, with the privilege of attending such a conference. Right now we’ve moved on a generation, and many of the Laureates this week were taught by the “golden generation” of Modern Physics. For example, Prof Douglas Osheroff studied under Richard Feynman and Prof James Cronin studied under Enrico Fermi (and also Murray Gell-Mann, the man responsible for the subatomic particles called quarks)
Today’s talks opened with something a lot more interesting to me than the biology from yesterday. Actually come to think of it, the entire theme of today’s talks and discussions was a lot more related to the Physics that I studied as an undergraduate. 2 of the talks involved measuring cosmic effects, one being cosmic x-rays and the other being cosmic microwaves. Prof. Riccardo Giacconi (prize winner in 2002) discussed his discovery of cosmic X-rays by flying X-ray detectors on Skylab (a very early type of space station) in the 60’s and looking at the x-ray structures of the suns corona. He was also involved in analysing x-ray experiments flown on the x-ray observatory Einstein, Hubble space telescope, and proposed the latest probe CHANDRA in 1978 (launched in 1999). He gave a brief history of the technological development in x-ray astronomy since the 60’s, showing the increase in detector sensitivity to X-rays over time. In 1978 x-ray observations showed us the amazing crab nebula and its pulsar (a pulsar is a neutron star emitting jets of radio waves), binary stars in external galaxies, and indeed galaxy clusters themselves. It’s hard to believe these pictures were taken with an orbiting telescope millions of miles away, but then you have to consider that these objects can emit as much as 1000 more x-ray radiation than the sun itself. He also discussed the presence of dark matter (a type of matter which theoretically should exist, and comprises 23% of the entire universe!) by the collisions of 2 galaxies, and was also the first to find sources of X-rays which are now almost certain to contain black holes.
Did you know the age of the Universe is 13.7 million years old with an error of 1% (20 million years!) according to Big Bang theory? Prof George Smoot (Prize winner in 2006) had us all fascinated on a trip through the evolution of the universe and raised some very philosophical questions such as “why are galaxies different colours”, “why are there so many galaxies if there is only life on Earth (so far)” and “is there any order to the arrangement of the galaxies”? These far reaching equations led to the nature of his Prize, detecting the microwave background (some of the oldest stuff around as he modestly put it) using the COBE (Cosmic Background Explorer) launched by NASA in 1989. According to his theory, cosmic microwave background radiation is evidence the big bang occurred. When emitted, the Universe was 3000oC, and since then is a mere 2.7 K. Smoot discovered that this temperature varies ever so slightly from place to place in the Universe (it’s not homogenous). He also talked about a new probe called the Max Planck, which takes wedge shaped images of the universe and shows the temperature distribution. These distributions can be placed together to create a 3D map, of which Prof Smoot has some fascinating movies detailing. His enthusiasm for explanation of his work and thoughts caused him to stretch well over time, but nobody was complaining. Prof. James Cronin was absent from today’s meeting, which is a shame because I was looking forward to his talk on cosmic rays. As I mentioned already, he was educated by the likes of Enrico Fermi and Murray Gell-Mann, and helped in the discovery of the subatomic particle, the K-meson (also called a kaon). He also proved that by examining the decay of these particles, the reaction in a particle accelerator that caused it when run in reverse does not retrace the track of the original reaction. This shows that the interactions of particles may not be indifferent to time, and so symmetry is violated during weak decay. Not to worry, we had 2 particle physics lectures to look forward to.
Prof Martinus Veltman (Prize winner in 1999) treated us to a history lesson of high energy particle physics, something which I am happy for because since teaching it 3 years ago I haven’t seen a lot of it. From humble beginnings of the Irish priest Nicholas Callan producing 600,000 volts in Kildare in 1836, right up to the modern day LHC (large hadron collider) which will be powered up in CERN in August this year, he detailed all particle accelerators in between. Its great the way science is built on other science because Wilhelm Roentgen (the 1st Prize winner in 1901) used the high voltages geberated by Callan and and another German inventor for the discovery of X-rays, and Bequerel used high voltages to discover radioactivity. In chronological order (for anyone who is interested!) the accelerators are the Cockroft-Walton accelerator (Walton was from Carlow by the way, and won the Physics prize, the year escapes me though), in which accelerated protons smashed into Lithium atoms, the SLAC “Monster” (Stanford Linear accelerator on the San Andreas fault in the US), the cyclotron, the cosmotron, the synchrotron, the tevatron, storage rings (the first time actual beams were collided rather than particles into a target), and soon the LHC. Prof. David Gross (Prize winner in 2004) echoed the principle purpose of the LHC, to look for the elusive Higgs boson, which is a subatomic particle that theoretically should exist, and has been proven in many models but which has not yet been physically observed. This elusive particle plays a key role in the Standard Model of particle physics, providing as he called it the “missing link” into showing how elementary particles acquire properties such as mass. He told us also how it is a significant step in the search for a Grand Unified Theory, which seeks to unify 3 of the 4 fundamental forces, electromagnetism, the strong nuclear force and the weak nuclear force. This would still leave gravity to be explained (as of yet there is no particle that is responsible for gravity). Other particles are suspected to be found with the LHC such as strangelets, micro black holes, magnetic monopoles (a particle consisting of only a north or south pole!) and “supersymmetric particles”. This part of the talk confused me to no end, probably because my experience of it was little to none. Supersymmetry (SUSY) looks beyond the Standard Model of particle physics, and is an attempt to explain the energy transitions to create the particles, and to unify the theories. The graph shows the energy modelled energy required to unify the forces, and the energies created by the new LHC. Integrated into this is the murky term “string theory” of which I was almost completely lost, but its an attempt to explain the presence of dark matter and dark energy in the universe.
So all in all, there was a lot in Wednesdays lectures. Lots to note, and it’s extremely interesting to hear the research going on in particle physics. Lucky I had the quantum and modern physics modules or I would have been totally lost!
In the afternoon questions and answers session, Prof Giacconi also gave his thoughts on the future of astrophysics, including a fair amount of politics on securing funding, and communication of results, important stuff for any physicist. Prof. Gross was extremely both popular and busy, attracting by far the largest crowd to his questions and answers session (he had to host the crown in the lunch tent because there were so many!). He answered all kinds of general questions, from the origins of particle physics right up to present day, and discussed the powering up of the LHC in August 2008. I’m not entirely sure if all the students were there out of general interest, but I got talking to a few German lads working at the Max Planck institute, who reckoned lots of the PhD students there are responsible for analysing the Terabytes of data generated every day at particle accelerators. Things can only get worse when the LHC powers up! Socially it was fairly quiet in the evening, a beer and a massive ice cream was on the cards to cure the addlement my brain went through from the tough day of talks. We relaxed with a classical concert of Beethoven 7th symphony put on for us in the evening in the town theatre.

Tschuss!
Jim