Anuj Purwar

Camping in a volcanic crater

Last week I was in the island of Maui in Hawaii to attend the Division of Nuclear Physics Joint Meeting of the APS and JPS (Japanese Physics Society). The meeting was held in the Ritz-Carlton. Was I living the high life! Here is a picture from my room at the Ritz.

The organizers had done a great job, getting a rate of just $165 instead of the regular $350 or so. In addition it had been organized so that we either had a morning or an evening free allowing us to do some sightseeing. Of course the flip side was that sometimes the sessions would go into the night. Still once again great organization. Maui is a volcanic island with blue oceans and pretty beaches; white, black & red the beaches come in all colors. And then there are the mountains rising all around. I ended up doing several hikes: from Iao national park with it's dense rainforest with delicious strawberry guavas 

to camping inside the volcanic crater: Haleakala or House of the Sun. Here is a picture of our little camp.

You can see the volcanic cinder cones in the background. The crater itself is huge, apparently it can fit the entire island of Manhattan! We hiked around for several hours encountering some very interesting landscapes from rainforest to "moonscapes". Here is a picture of Anita next to one of these "moonscapes".

We also went around the silversword loop full of these endangered plants which look like an alien with a hula skirt, specially in this volcanic other worldly landscape.

After a strenous hike with all my equipment (see my picture with my backpack standing on an old lava flow in the crater)

we treated ourselves to a fancy lunch at Mama's Fish House. For dessert we had this amazing dessert: black pearl, a chocolate mousse filled with a passion fruit sorbet in oyster shaped cookies..

It was undoubtedly one of the best desserts I have ever eaten. It was so pretty that we were almost a bit reluctant to eat it!

Free Coca Cola and Pentaquarks

For each of the previous 5 times that I went to the Los Alamos cafeteria, I bought a 20 oz. bottle of Coke, all of which had a winning cap which allowed me get a free 1 L bottle of Coke. The probability of winning in any one bottle is 1/6 and since I won 5 times in a row... I just pulled off something that has a chance of 1/7776! I won't even try to calculate how far this is from norm in terms of sigma, the favorite term that physicists like to use to determine the likelihood of a signal.

So what does this have to do with pentaquarks, that exotic state of 5 quarks. A few days ago I attended a seminar by Ed Hartouni from Lawrence Livermore National Lab, in which he described some analysis he did searching for a pentaquark signal with a fixed target p+p experiment at Fermilab. They didn't find anything. But there are several experiments which show pentaquark results: effects of several sigmas even and then there are several experiments which published results indicating no pentaquarks. What does this mean in terms of statistical significance? This brings me back to the incident of 5 consecutive free Coca Cola wins for me. If I naively assume that each of these wins is independent, then I get the absurd result of 1/7776. However if I assume that these events correlated, then I get a much more reasonable probability of 1/6. Obviously we need to be more careful when we quote results in terms of sigma as there might be unforseen correlations. It also reminds of a news headline I read "50% of scientific papers are wrong". This applied to medicine but sometimes I wonder it applys to physics. For instance with regard to pentaquarks, I know that my experiment PHENIX had "Seen" a pentaquark signal last year. But fortunately before the results became official, a mistake was found: a miscalibration in the timing of the Electromagnetic Calorimeters lead to a false signal. And yet this finding was never published... In some ways there is more to learn from these mistakes than another "discovery". I wish that some of these negative finding papers were also published so that some other experimental collaboration does not make the same mistake.

Bethe Symposium

This had been one long break from the blog for me. I've just been so busy: from the usual hikes having guest over for a week to preparing for the APS Div. of Nucl. Physics conference coming up next week. As a result I have built up a huge backlog of things that I wanted to write in this blog. I shall start with the Bethe Symposium, held in Los Alamos last month on August 19, 2005. This was organized by Mikkel Johnson in memory of Hans Bethe one of the giants of physics in this century and a hero for physicists everywhere.

The symposium was attended by his immediate family as well as several well known physicists like Sidney Drell, Gerry Brown, Harold Agnew, Edwin Saltpeter and others. It was such an inspiring experience to hear all these famous people talk and reminiscence about Hans Bethe. The picture below shows Harold Agnew a former director of Los Alamos describing Bethe, the next door neighbour during the Manhattan Project days. The lab had a bit of wild west in those days. Harold described how his backporch didn't have a door, so they simply "borrowed" some doors from some of the tech areas in the lab. Something like this now would lead to a federal investigation and FBI and what not!

Bethe continued coming to Los Alamos during summers because he loved to climb the mountains here. Later he worked towards control of nuclear weapons.