Well, it went wonderfully. What went wonderfully? My one hour (plus) talk at a local church in the neighbourhood. I mentioned the backstory in a previous post. It was quite a long day in the end. I got up at 6:00am to write my “sermon” -which involved hunting with Google images for images which would illustrate the various themes I wanted to bring out. I sketched what I wanted to say mostly in my head and scribbled on a few scraps of paper, but the idea was that I did not intend to be scripted, but instead talk off the cuff. The scribbling was simply a means of ordering various themes.

We had a full church service, with some excellent singing (with the pastor Aaron Howard on the piano). And clapping, lots of clapping. There was some reading from scripture, with some nice verses chosen, and there was prayer. I have a problem with none of the above, I should say. It was not at odds with what I came to talk about: Science and science careers. These were good people, doing great things in their community, and that’s all that matters to me at this point.

In some cases, I was able to find resonance with what I wanted to say and what came up in the verses, and so I improvised a bit and incorporated some bits here and there as I listened. I got a rather grand introduction from a lady who writes children’s books about black inventors and scientists, which I thought was just perfect. I spoke for about an hour, and then there was an unexpected amount of really excellent questions afterwards, and so we went on for another half an hour.

I can’t get over just how pleased everyone was that I came out to talk to them. They’ve never done this before. We spoke at length about problems in the community and where -with limited resources- they could do more about getting kids exposed to science. I mentioned that they might consider not waiting for the schools to be “fixed” and take matters into their own hands. Why not have a “science club” for the young (and everybody else), right alongside their bible club, and just share information about good books, ideas of the day, etc, and get people from USC and other places to come and talk as guest speakers? They really could hardly believe me when I said that if they called up USC and asked, they could get more people to come and give a talk (e.g., “Please come and tell us something about DNA”), especially if they make sure that everything is ready and the person just needs show up and talk. They said they were going to try to use USC more. I encouraged them to make a niusance of themselves to get this to work.

Here I am with the pastor and some of the young ones:

Truth be told, the young person turnout could have been a lot better. The pastor was confused about this, but thinks that the message about what exactly this was to be did not really get to the schools. I offered to come out and do it again if they wanted to have another go at getting more kids.

One thing I talked about (more than I intended to, but that’s where the spur of the Continue reading ‘The Sermon’

One of our “missions” here at Cosmic Variance is to provide a glimpse into the lives of working scientists and to demonstrate (hopefully, to some extent) that academics are normal people.

A while ago, I wrote a post titled Debate a Dead Scientist - A Cunning Strategy, about a creationist class, dressed up as a philosophy course, in which part of the proposed curriculum was that Francis Crick (who was already dead) would speak to the class as an evolution expert. I made a bit of fun of this while commenting on how fraudulent it was.

That post prompted my good friend Chris Kyle to point out to me that academics - those normal people, we’d have you believe - can be even freakier when it comes to trotting out the dead.

Chris sent me links to the University College London Bentham Project, in which, as it says on the main site

At the end of the South Cloisters of the main building of UCL stands a wooden cabinet, which has been a source of curiosity and perplexity to visitors.

…

The cabinet contains Bentham’s preserved skeleton, dressed in his own clothes, and surmounted by a wax head.

The full story is here if you’re interested. But the part that I find hilarious, and totally demolishes my hope of convincing you that academics are normal is

Not surprisingly, this peculiar relic has given rise to numerous legends and anecdotes. One of the most commonly recounted is that the Auto-Icon regularly attends meetings of the College Council, and that it is solemnly wheeled into the Council Room to take its place among the present-day members. Its presence, it is claimed, is always recorded in the minutes with the words Jeremy Bentham - present but not voting. Another version of the story asserts that the Auto-Icon does vote, but only on occasions when the votes of the other Council members are equally split. In these cases the Auto-Icon invariably votes for the motion.

Oh well.

The Wikipedia article on countries with nuclear weapons is sobering reading. This map is from the article, although the color-coding is a bit misleading. (3quarksdaily points to more maps.)

• The United States, Russia, United Kingdom, France and the People’s Republic of China are the five nuclear powers recognized by the Nuclear Non-Proliferation Treaty (NPT). Not coincidentally, they are also the five permanent members of the UN Security Council. The US and Russia have about 6,000 active warheads each, while the others have a few hundred each. According to the NPT, only these countries are permitted to have nuclear weapons, and they are prohibited from sharing weapons technology with other countries.
• India did not sign the NPT, and exploded its first nuclear weapon in 1974 (in a test perversely named “Smiling Buddha“). In 1998 they tested “weaponized” nuclear warheads (I don’t know what that means) in Pokhran-II. Numerous complaints and sanctions followed, none of which had any appreciable effect, and the controversy eventually died down. Possession of nuclear weaponry is considered to be a crucial part of India’s self-image as a world power. They are now recognized by the US as a “responsible nuclear state.”
• Pakistan is also not an NPT signatory. They performed their first nuclear test in 1998, in response to India’s test. In 1999 they signed accords with India, agreeing to a bilateral moratorium on nuclear testing. A.Q. Kahn, leader of the Pakistani program, confessed to being involved in a clandestine network to share nuclear weapons technology with Libya, Iran, and North Korea; he was pardoned by President Perez Musharraf in 2004. There is some evidence that his network was also collaborating with the Taliban and al-Qaeda.
• Israel has not acknowledged possessing a nuclear arsenal, but it is an open secret; Israel is not an NPT signatory. (In fact, India, Pakistan, and Israel are the only sovereign states not to ratify the NPT — although see below.) They probably have several hundred warheads, comparable to the stockpiles of China, France, and the UK.
• North Korea, in contrast to Israel, has publicly claimed to have nuclear weapons, although some analysts remain skeptical. After ratifying the NPT in 1985, they withdrew in 2003; no other countries have ever withdrawn from the treaty. In September 2005 they agreed to scrap their existing nuclear weapons and rejoin the NPT, but later stated that no such steps would be taken unless they were supplied with a light water reactor.
• Iran is of course an interesting question.
• South Africa produced a few nuclear weapons in the 1980’s, but later dismantled them. They are the only nation to build nuclear weapons themselves and later give up the capability.
• Saudi Arabia has stated that they might need to develop nuclear weapons, although they deny actually having done so. Some recent reports claim that the Saudis have embarked on a weapons-development program, with aid from the Pakistani nuclear program.
• Several republics of the former Soviet Union found themselves in possession of nuclear missiles upon the collapse of the USSR in 1991: Ukraine, Belarus, and Kazakhstan. All have subsequently transferred the weapons to Russia and signed the NPT, and are currently nuclear-free. Concerns persist over the possibility that weapons technology was sold through the black market; Ukraine, in particular, was known to be active in selling at least conventional technology.
• Several industrialized nations are thought to be capable of putting together nuclear weapons with very little effort, including Canada, Italy, Germany, Lithuania, and Japan. For the most part there is no evidence that these countries have any desire to pursue such a course. However, former German defense minister Rupert Scholz has argued that Germany should consider nuclear weapons as a way to respond to terrorist attacks.
• Iraq, of course, had a program to develop nuclear weapons that suffered a number of setbacks, notably the Israeli air strike on the Osirak nuclear facility in 1981. After the 2003 invasion, the Iraq Survey Group concluded that the nuclear program had been abandoned in 1991, along with most other WMD programs, but that Saddam Hussein had plans to re-start the program once multilateral sanctions were lifted.
• As part of NATO agreements, the US provides tactical nuclear weapons for use by Belgium, Germany, Italy, the Netherlands, and Turkey.
• A number of countries are known to have begun programs to develop nuclear weapons, only to abandon them and eventually sign the NPT; these include Sweden, Switzerland, Egypt, Philippines, Libya, Australia, Poland, Romania, South Korea, Brazil, Argentina, Taiwan, and Yugoslavia.

What are the chances, with all those weapons out there, that someone will use one, say in the next fifty years? Extremely high, I would guess. None has been used in the last fifty years, it’s true, but for most of that time we lived in a bipolar world with clearly defined lines of engagement and relatively symmetrical capabilities and liabilities. (The above list doesn’t even mention non-state groups, of course.) A more fragmented situation exponentially increases the number of events that could lead to a nuclear strike, including the possibility of accidents. And the number of nuclear-capable states shows little signs of decreasing in the near future.

For what it’s worth, Russia, India and China have officially adopted a No-First-Use policy regarding nuclear weapons; the United States, United Kingdom, France, Israel, Pakistan and North Korea have declined to do so. In the 2005 revised Doctrine for Joint Nuclear Operations, the Pentagon listed the conditions under which a nuclear first strike could be requested, which includes basically any situation in which someone might want to use them. The Doctrine itself was originally published freely on the Pentagon web site, before being cancelled — that is, removed from the site, but not necessarily revised as doctrine. The original document can be read here. Britain and France have similarly asserted the right to nuclear first-use. It is hard to imagine that countries generally thought of as less responsible than the US, UK and France would feel much compulsion against using nuclear weapons if they felt threatened.

Once any country strikes another using nuclear weapons, the presumption against further use will be considerably lowered. The consequences are hard to imagine, simply for being so terrifying.

Well, I’m recovering from an excellent hike up Mount Wilson with the USC Neurobiologists earlier today, so while I do that, I’ll tell you about last night. Recall that the LA Times Book Festival is happening this weekend.

I came closer to seeing a realization of one of those topsy-turvy scenarios I often fantasize about, where more “academic” pursuits, or at least those more associated with the life of the mind, are celebrated in full Hollywood fashion. (I envision it in the context of science and scientists….imagine an Oscar-Like awards ceremony for the year’s best science papers, watched by millions on TV in prime time… but this will do for a start.)

Yes, I went to my first LA Awards ceremony, the Los Angeles Times Book Awards, and although I joked about Oscar analogies in a previous post, it actually was rather Oscar-like. The setup of UCLA’s Royce Hall for the event was very plush indeed, with a podium each on the left and the right of the stage for smooth transitions, and a giant screen for either relaying of the closeup image of one or other presenter, for the showing of acceptance speeches from those “who could not be with us at this time”, or for the display of graphics accompanying shortlist readings, etc. Just like in the Oscars. And yes, they had (why?!) the usual eye-candy woman bringing on the actual award, and the announcement envelope to hand to the presenter at the appropriate time.

The Master of Ceremonies was Dana Gioia the chair of the National Endowment for the Arts (there he is in full sail, at right, click for larger image). I was rather pleased that the first category announced was the Science and Technology section. (Perhaps it was in honour of there being a blogger from Cosmic Variance in the audience?) I found myself very excited by all of the nominees in this section, and was intrigued by the winning one, Diana Preston’s “Before the Fallout: From Marie Curie to Hiroshima”, which I’d somehow not heard of before (No, I don’t know how I missed it either). I had the pleasure of chatting with Diana Preston (and her husband Michael) at length at the After Party (see later), and got the chance to hear about how she went about finding a way into a field -atomic physics- about which she had no expertise (no science background, she said) to the extent that she could win a prize for her science writing. It was also interesting to hear her and science writer K. C. Cole bond over the various Manhattan project people they’d managed to talk to over the years in book research. (K. C. is working on a biography of her mentor Frank Oppenheimer at present).

I really want to read Diana Preston’s book, as well as several others on the shortlist in that section, as I mentioned in the previous post. Speaking of others, I finally met Sean Carroll. No, not our Sean M. Carroll, the Biologist Sean B. Carroll. We were together in line to go into the room where the After Party was to be held, which was taking a bit of time, for reasons I only figured out too late. I introduced myself and joked with him about the name-sharing thing, and told him about the blog. His Evo Devo book (“Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom”) is another one high on my list of things to read. There was an excellent review and discussion of it in the New Yorker late last year by the way. You might be able to get it online. I’d meant to blog about it back then but somehow did not get to it.

Here is the list of winners and presenters. I took it from the blog Nimble Books: Continue reading ‘I See Book People’

Yes, we go the extra mile for our students here at USC… My colleague Gene Bickers does more than that. He walks on burning coals every year as part of that extra mile (photo courtesy Steven Straker):

The point? Walking across burning coals is no big deal. You don’t need special mystic powers to do it. It’s just a matter of freshman physics: the coal simply does not have good enough heat conduction properties to transfer enough energy to your foot to burn it as you walk across. So you should only be impressed by a person walking across something like a red hot steel plate (much higher heat conductivity) and not burning their feet. Then maybe entertain the thought that they have mystic powers…. or something…..

I’ve done the hot coal thing a number of times myself (not at USC). Enough to know that you don’t have to be anything more than just a regular person to do this. No mystic powers needed. Sorry.

-cvj

In case you’re in the area, please don’t forget the Los Angeles Times Fesitval of Books this weekend, held over Saturday and Sunday at the UCLA campus. It is a blast. There are book authors of various types and genres being celebrated as the celebrities they should be, with young girls and boys gasping and fainting as their idols go by. Well, not quite, but I like to imagine this. Here is the website with the schedule. As they say there, you’ll have:

131,000+ Passionate Readers
370+ Famous Authors
300+ Popular Exhibitors
900+ Loyal Volunteers
6 Exciting Stages
2 Interactive Children’s Areas

I went last year and can verify that it is a lot of fun.

Actually, this year I won’t be able to see much because I promised to go with a big group to the top of Mount Wilson the fun way, which will take up most of Saturday. On Sunday, I’m doing the church sermon thing I mentioned earlier and then they are taking me to lunch and doing more Q&A, so I don’t know when I’ll make it over to UCLA that day.

I do get to go to one event for sure. My first LA Awards ceremony!! On Friday night I go to the LA Times Book Awards. I won’t be live blogging from it, as was done last year at The Elegant Variation. I’ll be too busy being embarrassed. You see, I looked at the list of nominees just now, and while several of the books are on my “must get around to reading this gem” list, such as (from the Science and Technology category) Chris Mooney’s “The Republican War on Science”, and Sean B. Carroll’s “Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom”, I have not read anything that has been nominated. I’ve just been too busy the last several months. So it’s going to be so embarrassing - I’ll be exposed as a fraud! On the plus side, I’ve been promised that I’ll be introduced to lots of interesting authors, such as Mariana Gosnell, the author of “Ice: The Nature, the History, and the Uses of an Astonishing Substance”, which I suspect is a truly excellent book. I’m going to get in touch with my inner groupie, for all the right reasons (but remaining slightly aloof on the outside of course).

Hmmmm… I wonder if I can speed-read a few of these overnight? And whatever shall I wear…do I finally get to wear that Tuxedo I bought a while back? Is it too late to rent some expensive jewelry, or get a jeweller who wants the red carpet publicity to lend me some?

-cvj

Well, a lot of us are reading a certain 140 page document that was released yesterday. The National Academies Committee on Elementary Particle Physics in the 21st Century (”EPP2010″) released its final report at a public briefing. It is entitled “Revealing the Hidden Nature of Space and Time: Charting the Course for Elementary Particle Physics”, and it is available as a pdf file at this page.

Just so you know what this is about, the committee - made up of several of the most distinguished scientists you can think of - describes its charge in the preface:

The principal charge to the Committee on Elementary Particle Physics in the 21st Century was to recommend priorities for the U.S. particle physics program for the next 15 years. Described in the Executive Summary and more fully presented in the Overview, the committee’s considered response is laid out in detail in the main text of this report, which begins by discussing the scientific challenges in particle physics and conveying the current status of the U.S. program, and then presents the committee’s consensus on the best way to sustain a competitive and globally relevant U.S. particle physics program

A few glances reveal that there’s just excellent material in the report, and I will make it the top item on my reading list for the next day or two, as a report like this is a good way of stepping away from the daily grind and reminding us (at least in part) about what we’re up to in this endeavour.

Skipping ahead to the findings and recommendations, they break down the key questions into three categories:

• Can the forces between particles be understood in a unified framework?
• What do the properties of particles reveal about the nature and origin of matter?
• What is dark energy, and how has quantum mechanics influenced the structure of the universe?

Then they proceed to describe propects for addressing these questions within the context of the worldwide effort to do particle physics, but particularly focussing on the U.S. role, suggesting key strategies for the future. There is a lot of focus -as there should be - on the Large Hadron Collider (LHC) and the International Linear Collider (ILC). (If you don’t know much about those experiments, please follow the links I put in their titles, and also have a look through the archives of this blog. JoAnne, among others, has done some excellent writing about them.)

Here are the Findings and Recommendations of the Committee, snipped from the pages for you (please read the rest of the document though, for context, data and more in-depth discussion):

Continue reading ‘The Future, By Committee’

Ali G interviews Noam Chomsky. I’m not really sure what there is to add to that, except my admiration that they pulled it off. Check Wikipedia if you’ve never heard of Ali G, or of Noam Chomsky. Via Omni Brain, by way of Mixing Memory.

It is that time of year again. Because I am insane, I am teaching -by choice- two classes this semester. One of them is quite small, having 12 students, the other is not. The small class is my electricity and magnetism class. With a class this small, it is nice sometimes to have a change of scenery, and -if the material can handle it- I show up one sunny Spring day (after the hard slog through rainy Winter days) and declare that we are going outside to sit under a tree. There are several lovely spaces on the USC campus perfectly suited to this, and so we go outside. Last year, when I first had the idea for doing this, eventually I thought to buy a little portable whiteboard in case I need to write or draw something. (I discovered that the board fits perfectly into my Brompton’s front carrier bag, sticking pleasantly out of the top as I cycle along!)

It’s just a perfect setup actually, since this time of year usually coincides with the last part of the class where we are doing Special Relativity. I can think of few physics topics which are better suited to sitting outside and discussing under a tree -with a few diagrams and equations- than the classic thought experiments of Special Relativity. Here’s everyone in the class (except Chris Cantwell, who unusually could not make it this time), and also the whiteboard, my coffee cup, and the Brompton (of course):
(L to R: Michael Crampon, Jeff Pennington, Michael Johnson, Douglas Mason, Omar Hussein, Aleksandr Rodin, Amanda Fournier, Christopher Winterowd, Christopher Palmer, Justin Seymour, Matthew Recker.)

You can see, if you look closely, the last remnants of the moment of confusion that appeared on their faces from just being told that a vector can have zero squared length while not itself being zero. (That’s a “null four-vector”, we were talking about, for the uninitiated. You need them for describing things that move at the speed of light, for example.)

I have to design them a final exam very soon. Time for a trip to the Cat and Fiddle then, some evening soon. I’m going to see if I can get in a “fun” question at the end again, like last year. During the exam last year, one student (Lauren Schenkman) raised her hand to ask a question. I thought there was a typo or something on the exam. No, there wasn’t. Her question - asked cautiously and respectfully, was, “Are you serious?”. I love that. Here was the question:

Continue reading ‘Relatively Pleasant’

Having traveled from Italy to England on Saturday, spent Saturday night at my parents’ house, traveled from England to Syracuse on Sunday, and then taken a one-day trip to Michigan State University to deliver a seminar, I am finally back home for an extended period.

As I mentioned in passing in my last post, the talk I enjoyed most at the meeting on Ischia was a joint talk given by Anthony Lasenby and Mike Hobson, from Cambridge University. I thought I’d give a brief description of the topic, because the talk made the subject much clearer to me than it had been.

The topic was Bayesian Evidence, which is a method through which one may compare how well two competing theories explain a given set, or sets, of data. I should say at the outset that this method, and related ones, have been being discussed in the cosmology community for some time now (my postdoc has even written a paper on it) but I haven’t paid anything like the attention to it that I should have. I’ve been vaguely keeping an eye on what people say when discussing it at meetings, but that’s about it. I should also point out, as will probably become evident rather quickly, that I am not an expert in statistical techniques for data analysis. Having said this, the fact that this talk interested me nevertheless is another measure of what a nice performance it was.

When one reads papers describing new results in cosmology, one pays attention to the error bars on a given result. To take a topical example, consider the evidence for a scalar spectral index less than one, as inferred from the three-year WMAP data. The measurement is quoted as n=0.951(+0.015)(-0.019). It is usual to interpret these “one-sigma” error bars as Gaussian; that is to say that, since one needs to add more than three multiples of 0.015 to the central value 0.951 to reach unity, one says that this constitutes a measurement of n<1 at greater than 3-sigma and that consequently there is less than a 1% chance of getting this result randomly.

Now, there isn't anything wrong with this necessarily, but there is something missing from such a description. When one uses n in a fit to the data, one has one more free parameters than one does when leaving n fixed and just fitting the other parameters. Such a better fit might be important of course, but it shouldn't be a surprise to anyone that one can get a better fit by using more parameters.

So there are two competing things going on here. The first is the fact that new physics can provide a new parameter, which, when allowed to vary, can provide a better fit to the data. One could think of this as a net plus. The second is that it is just easier to get a better fit with more parameters and so there is some kind of net minus associated with every new parameter one adds.

The latter effect is what we mean by Occam's razor - namely that if two sets of parameters (read two theories) fit the data similarly well, then the simplest one (the one with less free parameters) should be preferred.

Bayesian evidence, the topic of Anthony and Mike's talk, is a statistical method to provide a quantitative measure of the Occam's razor part of this competition. It allows one to compute the odds of one theory versus a second theory being the right explanation for a set of data, in a way that quantitatively rewards a theory for reproducing the data more faithfully than its competitor, and penalizes it for having more parameters.

To do this one defines the Bayesian evidence, E, as the average likelihood of a model over its prior parameter space. Thus, if one introduces a new parameter that doesn't improve the likelihood significantly over much of its range, then the evidence suffers for it.

Now, this all sounds eminently reasonable, but there is a catch of course, namely that there is no unique way to do it. Nevertheless, there are a number of different proposals, and the message that I am taking from reading a few papers and from discussions with colleagues who are much more expert at this than I am, is that one has to try a number of different methods, and if they all seem to give a significant result, then one can be confident that the result is a real one.

It is important to realize that, even when one has a method such as this to calculate the evidence, one has to make a somewhat arbitrary decision as to what value constitutes a result that is significant. In this paper, by Beltran, Garcıa-Bellido, Lesgourgues, Liddle, and Slosar, there is an amusing discussion of this, in which the authors note that models are typically ranked by the logarithm of the Bayesian evidence, ∆ ln E (the logarithm of the ratio of evidences for the competing models) , and quote the famous mathematician and astronomer Sir Harold Jeffreys

… a useful guide is given by Jeffreys [12] who rates ∆ ln E < 1 as ‘not worth more than a bare mention’, 1 < ∆ ln E < 2.5 as ‘substantial’, 2.5 < ∆ ln E < 5 ‘strong’ to ‘very strong’ and 5 < ∆ ln E as ‘decisive’, in each case the decision being against the model with the smaller evidence. Note that a difference ∆ ln E of 2.5 corresponds to odds of 1 in about 13, and ∆ ln E of 5 to odds of 1 in 150.

If you’d like to read more about this, I found that the introductory sections of this paper helped me a lot, although there are others that might suit you better. At some point Lasenby and Hobson’s slides will be online on the conference website.

Having had such a nice talk pull this topic out of the back of my mind, I’m thinking of having one of the undergraduates who are working with me for the summer study this technique and teach me the details of it. If I get a better understanding I’ll report on it again.