Category Archives: Uncategorized

Physics and the Earth

As I delve deeper into the context of the physics I’m doing at the moment, all I seem to find is more and more information about the really serious state that the oceans are in.   I’m not sure whether this is just because I automatically hear much more about it now that I work in this field, or because it’s finally getting the much-needed press and so this stuff is being found out in the public sphere more and more.

In one way, I’m lucky because at least the physics I do is contributing to knowledge of the way the earth’s systems work, and in that sense I feel that I’m at least doing something positive about this issue on a daily basis.   Bubbles are at a crucial place on the boundary of the ocean and atmosphere and better knowledge of how many there are and where they are can only improve our understanding of the exchanges between these two great reservoirs of air and water.    On the other hand, all this will have a benefit a long way in the future (it’ll probably be ten years before models that incorporate this sort of data are really being used regularly), it seems that there is less I can do on a daily basis.   I choose stuff in the shops that has travelled as short a distance as possible to get there, I limit travel by car as much as possible, I don’t buy stuff I don’t need (like silly plastic toys that are only going to get thrown away), and I try to be aware of the consequences of my choices in life as much as possible.   I truely believe that all of those are important things to do.   And many people could do more of them and I could do better – it’s all dependent on the availability of information and the availability of real options.

However, I also feel that as a scientist, there should be more I can do.   After all, I understand the issues better than most people, because it’s part of my job to do so.   I understand how science works and how the evidence leads to these conclusions.   I have spent time in the oceans, and I’ve seen some of the effects of environmental changes (and I can imagine more).   Maybe I need to have more patience, and I’ll see places to do something extra soon.   But I feel that one of the biggest motivations for really changing your life to at least stop the problems getting worse, if not to start to reverse the recent trends, is knowledge and understanding of what is happening.   Really understanding it, not just looking at a picture of an ice floe and thinking “well, that won’t be there in the Arctic in the summer in ten years time”.    People really need to understand what it is that has been done, and then very quickly get over most of the anger and sadness that this knowledge causes and move on to actual changes that can be made.   Many of them are personal and they start with better informed consumers and voters.

Some days, when physics is a hard thing to do, when there are tough deadlines and a lot of responsibility for creating my own projects and direction, and when I’m floundering in new understanding of something, I wonder why I do what I do.     And then I realise that I’m one of the few people that really has a unique role here, to communicate what is happening from direct scientific knowledge and to convince people that these changes to their outlook and lifestyles really are important, and that they do make a difference.   There needs to be a connection between the scientific facts and the individuals whose actions have caused those facts.   And that divide should be bridged by a scientist.  Maybe people don’t really think about physicists as being those who are working in this area, but there is as much physics in all this as biology and ecology and chemistry.   I think that all scientists should do what they can here.   Just understanding how science works is something that you can try to share with other people, which may help them digest the information about the environment in the news.

If you’re interested, a great place to start informing yourself about ocean-related issues is the Shifting Baselines project and also the blog below:

http://www.shiftingbaselines.org/index.php

http://scienceblogs.com/shiftingbaselines/

And number one thing (in my opinion) on the list of “things that you could change but you probably don’t really know about” is to think very hard about any fish you may eat.   Overfishing is causing tremendous damage to the ocean, not just because of the removal of fish but because of the massive habitat destruction that dredging causes.   There are some fish that are still sustainably harvested, and try to find that out.   In the UK, I’m not sure about the best sources, but the Monterrey Bay Aquarium has  a great website with recommended alternatives to some of the fish that are found in the US:

http://www.mbayaq.org/cr/cr_seafoodwatch/sfw_sushi.aspx

I think that physicists really have a role to play here…   I took a course called “Systems” in the third year of my undergraduate degree, and the much of same thinking really applies to environmental phenomena.     We may feel that because our academic work doesn’t relate directly to environmental stuff, we are not in a position to talk about it.   But sharing our understanding of science itself is really invaluable.

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A wave is more than its equation

When I first started at the Scripps Institution of Oceanography a year ago, I was a complete novice when it came to ocean-related activities.   California thrives on these things and I stuck out as a rather puzzled (and pale) foreigner from an industrial town in the north of England.   “We don’t ‘av sea up thur, lad.   In’t that where them fish down at chip shop come from?”     So I thought I’d at least better learn to surf, so as not to look quite so out of place.

I went to some classes organised by the university.   I did all right, considering that I had never actually seen anyone surfing in real life and so I genuinely had no idea what I was supposed to be doing.   It’s amazing how hard it is for a proper Californian to understand that concept.  ” No, I really don’t know… where does catching a wave actually happen and how do I make it happen?”    I did enjoy it as well, except for the class with really high surf when I swallowed more ocean than anyone could possibly have intended and consequently felt like vomiting for most of the last 20 minutes.     I didn’t give up though and I did learn to surf.

Mostly, I learned that surfing is an amazing example of physics in action.   You have all these wavepackets coming along, steepening as it gets shallower and all travelling at a speed which depends on their wavelength.   You see waves interfering and you see when the waves start to become non-linear as the assumptions of the simple wave equation break down.   And you are in the middle of this, frequently (at least in my case) upside-down a metre or so beneath the breaking wave crest, experiencing turbulence in a very personal way.   I thought back then of writing a piece for a physics magazine at home about how all 1st year undergraduate students should be taken off to a beach and taught to surf, so that they could experience wave physics first-hand, and appreciate what all the equations really mean in practice.

And now I discover from the video below, that someone actually teaches this class at Scripps and I never knew.   Good for them, but boo hiss that I didn’t find out until now.    I really think that this sort of class should be offered to all physics undergrads, so that they don’t forget that it all connects to the real world.    I wish that I’d known – I’d have asked for a copy of the course material so that I could see how it was presented.   I’m going to push for things like this to be more common when I get back to the UK.   I admit that surfing in the UK might not seem as attractive, and indeed might put off those fainter of heart, but so what?

Go forth, physicists of the world, and surf…

it seems that embedded video won’t work on this site so here’s the link:

http://www.scivee.tv/node/6057

NeuroBayes: Sometimes sans Neuro

I went to the weekly computing seminar yesterday, because it was on a statistical data mining tool that is being simultaneously used by physics experiments and marketing firms. The speaker is a physics professor, used to work for the PLUTO Collaboration, DELPHI, and now is variously associated with CDF and CMS. The company, Phi-T, is now totally private, and employs a couple dozen ex-physicists, or physicists, depending on how much of a purist you are. The software is proprietary and closed source, and the speaker was severely vague about what specific tools were actually used, but there is an interface in C++/ROOT/C#/Lisp already made, so its (supposedly) trivial to use, with a discounted academic licence.

So what is it? Basically, you have a vector of measureables, like detector channels, and some target, like say Resonance mass. Or Age, profession, #kids, and your target is “How much will this person cost us in Health Care in the next n years.” You then train the thing on your historic or simulated data, and it generates Bayesian posteriori distributions for new data. This is pretty common in neural computing literature, but this thing seems actually practical.

The only really fascinating thing is the generality of the thing, which was (supposedly) applied with minimal expert consultation on problems like car insurance premiums, to B_s mixing at CDF. Here’s a list of referred journal articles with their stamp. So whats inside? A neural network you say? No! The guy said in most applications they skip the neural net entirely and just use “Other” statistical methods. It’s clear that he was using some kind of input decorrelation like principle component analysis, but he wouldn’t say what specifically. He used a bunch of phrases that were cryptic to me like “zero layer network” to mean something other than a perceptron (I asked), and “zero iteration training” of a network. Maybe these things mean something to yall statters, but nothing to me. Anyways, the output of whatever was a discretized probability histogram that got splined together.

I’m unconvinced that the “default settings” he mentioned could schedule re-stocks for the largest book distributor in Germany AND find the X(3872) resonance, but what do I know? He also said that the companies own stock were controlled by this thing, but that selling it for this purpose is somehow illegal. Anyone know what he was talking about? Here’s a paper on it, by the speaker.

In the end, the talk was a sales-pitch/head-hunt, but if anyone out there needs to solve a highly nonlinear problem and has a cushy grant, go nuts.

Quantum Mechanics in Your Face

If, today, you feel as if you should be doing work, but don’t really want to do any, may I suggest a video of a Sidney Coleman Lecture: Quantum Mechanics in Your Face? You’ll learn and be entertained.

The lecture is fantastic and consists of the late, great Coleman discussing a version of Bell’s theorem (which is much easier to understand than the standard treatment), and then going on to discuss the “mysterious” “collapse of the wavefunction”. It’s great stuff. All that’s required for enjoyment is a basic undergrad QM course…

Creative Writing Assignment

Before a seminar last week, I was discussing a colleague’s masters thesis, and she told me something I’m fairly jealous of:  She gets to invent her own physics words.  You see, this colleague comes from Ukraine, and her University has recently changed its thesis requirements from Russian to Ukrainian.  The two languages are closely related, but have significant differences in alphabet, vocabulary and grammar.  Ukrainian has been the official language of the Ukraine since 1991, but it was suppressed to varying degrees during the Soviet Era, and the CIA Factbook lists currently at 67% of the population claim it as their native language.  Since it has only recently been officially used at the university level, there are many technological words which are currently loaned from Russian or English.  This isn’t really unique to her situation, as that anyone who studies physics in any language has solved a problem by an ansatz, and heard of bremsstrahlung*.  What is unique is that there is pressure to develop Ukrainian, and therefore pressure to remove these loan words.  She was vague about how many loan words would be officially tolerated, but indicated that some technical vocabulary could be naturally adapted, but some would need to be basically invented from scratch to make them genuinely Ukrainian.  That’s got to be 50% fun, and 50% intractable.

*Bremsstrahlung is in firefox’s En. spell checker.  Thats awesome.  Ansatz isn’t, but ersatz is?

Bubble Bath

I had a Eureka moment this week. Fortunately I was not sitting in a bath at the time and so I did not have to decide whether to suppress the urge (apparently written into the laws of physics for moments like this) to run around the streets naked, shouting happily about my discovery. Thinking about it though, if I’m ever going to try that, it should be while I live in southern California near the beach. In my neighbourhood, such behaviour would probably just count as part of the social background noise rather than anything significant.

The Eureka itself was to do with how bubbles behave acoustically when fragmenting in turbulence (for example underneath a breaking wave). It turns out that some bubbles are disguising themselves acoustically as other bubbles (because the dominant resonance is not at their natural frequency). This explains a gap in the data which was previously unexplained, and I am very happy because my model matches the data pretty well. Or, it matches it pretty well up to now. There are still lots of things to be tested, but the fact that it explains this major feature is very encouraging. So I worked all this out, plotted most of the relevant stuff and hopefully this is sufficient for the time being to exorcise the bubbles-on-the-brain demons. Just before I worked out what was going on, piles of ideas were sitting untidily round in my head, overflowing into corners that they really didn’t belong in (for example, the ones associated with eating yogurt and inventing cocktails). They jostled each other and squeaked and squawked and squeezed and generally wouldn’t leave me alone. So now they’ve been put in order and I can get on with some other things. Good ideas. Sit. Stay…

Unclear physics

I was reading a book called “The Revenge of Anguished English”, and although the content doesn’t live up to the promise suggested by the title, there was a nice physics typo mentioned near the end: “He got his degree in unclear physics”. The question is whether that tiny letter substitution makes that much difference to most people who might be reading a newspaper biography of someone. Are nuclear and unclear synonyms to everyone who doesn’t have a physics degree? I would guess that for all practical purposes they could often be interchanged. I don’t want to be snobbish about it – I’m sure that I wouldn’t blink at an article about”More sculpture” when it was meant to be about “Moore sculpture”. Perhaps nuclear physicists should be upfront about it and just go with it. An “unclear power station” sounds quite aesthetically pleasing, as if it faded into the background on sunny days. And at least G.W. Bush could talk about such an entity without inducing a snigger from every science graduate (and indeed every literate person) in the English-speaking world.