Halzen says this is something he feels passionately about. He calls today's American graduate school "unfortunate" because it still assumes you take courses, learn all of physics and then do research, when nobody can learn all of physics any more. The Belgian system he came up in, he says, let him learn by working on problems.
So it could have been done, it probably could have been done earlier, but in its present form, and for the discoveries we make, the electronics, I don't think we could have done it with Amanda analog signals. It's pretty essential to have the technology that NiGren and the Berkeley group developed for the data acquisition.
I want to ask you, because I knew you as a student of yours, albeit not as a graduate student, I think that would be a great treat, but as a student in a class about for advanced undergraduates and graduate students and particle physics, why do we conflate scientific ability with educational or pedagogy ability? words um you know someone who's a pilot may be extremely skilled at flying but we don't ask you know him to like teach flying necessarily although you and you can actually teach flying without i'm a pilot in my side hustle uh to to pay the bills here at the state university of california uh but i want to ask you why is it that we do that do we do do they do that in europe is is that common um you know that we have an expectation that because francis or brian are good at scientific research that they're also good at teaching or or is that a mistake
well i this is one this is one of the things i feel passionately about and never had the time to do much about it but i think that uh you know the graduate uh school that exists today at american universities uh is uh in a sense unfortunate it still lives in the days that you take courses and learn all of physics and then do research first of all you cannot learn all of physics anymore you cannot even learn all about some specialized subject in physics no so the way i have i i have everything i know and the belgian system at the time allowed you to do this everything i know i've i've learned by doing research you get interested in a problem you have to solve it you learn everything you need to solve that problem and that's how you learn and you remember by the way and uh i think uh that's the ideal way that you know trying to get a background of all of physics before you start doing research is an illusion uh which we which we are still living in in our present system of graduate schools
yes yes and it's it seems to be you know sort of strange how the european system influenced the american system you know the the germanic uh kind of uh emphasis on research and now most of the ludwig boltsman or max max planck institute they don't teach as i understand it so it's kind of ironic that the educators of the american system um they uh they don't do any education of their own anymore um so i wanted to talk a little bit about the technical details and the theoretical underpinnings of ice cube and and you've been kind enough to prepare some slides so i'll let you get set up to share the screen
okay so uh you know we want to detect uh neutrinos from space because we want to do astronomy with neutrinos rather than with photons and we know how to detect neutrinos this is an experiment in japan in a deep mine and it's a huge tank of water and light sensors and that's how you detect uh neutrinos the problem with this beautiful experiment is that the theorists in their wisdom told us that uh and by the way i'm not blaming anyone it was one of them uh told us that this experiment is 10 000 times too small to to do astronomy and catch the tiny flux of uh neutrinos that reach us from the universe so to make a long story short we build a detector that uh instead of water made out of water it's made out of ice and the phototubes are distributed throughout the ice and uh according to our wisdom as theorists it probably had a chance to detect cosmic neutrinos but no guarantees were given and so what you're looking at of course is uh it's not a real picture but so if you go under the south pole you stand the south pole station stands on three kilometers of ice and you go one and a half kilometers deep there are strings with uh the light sensors that you saw on the walls of the japanese experiment and so the strings are a kilometer long and there are 86 of them so the light sensors between strings are 17 meters apart and the strings are 125 meters apart and 86 of these strings fill a volume of ice with uh light sensors this idea by the way was uh born in 1960 a russian physicist mark came up with this idea. So the idea is certainly not new. So the challenge was to melt these sensors into the ice. And so we developed, that was the first big challenge. We developed technology at Wisconsin to do this. And the second challenge was, was this ice good enough? to act as a particle detector. And that's a long story. And the story is told in this slide. And I would spend the rest of your time if I went through this slide. But we made our major breakthrough when we realized that the light, blue light in ice, travels over hundreds and sometimes hundreds of meters. So this is compacted snow of 70,000 years ago. It's ultra-pure. And even in a lab, you cannot build a block that transparent to blue light. So that we didn't know that. That was pure serendipity. So these two things being solved, we built it and took data. And the idea is, you can imagine your block of ice here. And
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