I was reading this weekend in January's physicsworld some curiously contrasting articles on the state of physics funding in various countries. The UK has recently announced some serious cutbacks to their international collaborative projects, in an attempt to claw back 40 million pounds that was mis-spent a couple of years ago following an accounting error.  Whoops. For example, there will be the complete withdrawal by the UK from my favourite Large Hadron Collider experiment, ALICE.

Meanwhile, Japan's physicists are nervous after some major budget slashing by its government. There are fears that major research facilities there, such as the Spring-8 synchrotron in Hyogo, will be under the knife, perhaps to fund the new government's ambitious election promises.

However, across the Pacific, in the US, things are looking a bit rosier, at least if you work in the 'right' bits of physics. The National Science Foundation will get a 7% increase on its budget, and NASA a 5% increase. And just across the channel from the UK, France is dishing out a 35 billion euros stimulus package to its university and industy research programmes.

And in the same issue, there's an article looking at where the 'top' 158 physicists in the world began their research, and where they are now.  Of these, 30% were born in the US, but 67% of them are based there now. And those based in the US have about a 16% higher 'h-index' (a measure of a scientist's research output) than those based elsewhere.

For what it's worth, I've also done up a quick count of the job adverts in the back of the magazine. It (if you haven't guessed) is a UK magazine, and out of 13 adverts for jobs, four of them are based in the UK, and nine elsewhere in Europe.

I'm not sure what conclusion I should come to from these ramblings (safest not to come to any conclusion given the selectivity of my data source), though it does indicate what most physicists know already - if you want to do well in physics research, you have to be mobile. And particularly mobile in the direction of the United States of America.

In an earlier post I made the outrageous claim that three is a working approximation to infinity. If you thought that was ambitious, have a read of the following extract from an abstract that I discovered this morning while doing a bit of literature searching as part of my research. It's a great insight into the mind of a theoretical physicist.

 The present work studies the effect of additive noise on two high-dimensional systems. The first system under study is two-dimensional, evolves close to the deterministic stability threshold and exhibits an additive noise-induced shift of the control parameter when driving one variable by uncorrelated Gaussian noise...

Reference:   Hutt, A.  Additive noise may change the stability of nonlinear systems. Europhysics Letters, 84(3), 34003. (2008).  DOI 10.1209/0295-5075/84/34003

Did you spot the implication?   The author is implying that a two-dimensional system is high-dimensional.  In other words, two is a big number. Now, I don't know about you, but I live quite happily in three dimensions. This large number of dimensions doesn't cause me any problems. But, when it comes to analyzing how systems behave, there is actually a massive increase in the diversity of behaviour when we move from a one-dimensional system to a two-dimensional system. (By a one-dimensional system, I mean one that needs just one variable to descibe it, and a two-dimensional system is one that needs two variables to describe it. In this sense a pendulum is a two-dimensional system. To describe its state you need to know the bob's position and velocity.)  Two dimensions are pretty diverse, really.  The pendulum can sit still and just hang under gravity, or it can do its characteristic swing back and forth, but that's not all. If you whirl it to start with it can go round and round in circles, or, if you start it pointing vertically upwards and ignore friction, it will drop (but which way?), swing round, and end up back exactly where it started.

The physicist, and perhaps more so the mathematician, will then make great strides forward, and happily move from two to three, four, ten and even infinite dimensional systems, which are just further examples of high dimensional systems.  Visualizing what's happening becomes a bit tricky, but, in practice, once you've got used to the idea, there is not a lot of difference between two and ten.

Every time I blink I seem to get another email from a science journal that I haven't heard of inviting me to contribute to their most prestiguous publication.  It's all very flattering to get emails telling me that as a world leader in organic chemistry research I am invited to contribute to their well-read journal, but I am beginning to wonder about the validity of the science-journal based system of documenting and disseminating scientific research.   (NB In case you are wondering, I am NOT a world leader in organic chemistry research, but send out the email to enough people and you'll hit one who is...)

When I was a PhD student in the early 1990's (cue soppy nostalgic violin music)  I spent a lot of time in the library looking at journal articles.  Every month, a publication called 'physics abstracts' would appear in the physics library in Bristol - a huge thick thing that contained short summaries of research that was published in physics journals that month. It was nicely indexed by way of topic, and I could browse through it pulling out articles that might be relevant to my research. I'd then go and get the journal volumes off the shelf, find those articles (or maybe have the librarian order them for me from another library) and read them. Some of them would be useful, others not, but in this way I kept up to date with relevant work.

Now, I don't leave the office.  I can search the library catalogues, pull off PDFs of relevant articles, check which subsequent articles cite them, all without leaving the comfort of my office chair. The University of Waikato library has a fantastic new extension to it but I am yet to see the inside of it - I just haven't had cause to actually go down there to consult something that is not available online.

All that is great, but it has led to an absolute explosion in information. The ISI Web of Science, a popular tool for searching publications, looks at about 10,000  journals.  That's a huge number. I dread to think how large that 'physics abstracts' publication would be now. Finding a piece of relevant work can be like looking for a needle in a haystack of irrelevant information. I am forced to wonder just how many of these journals actually contribute significantly to the advancement of science.  How much work is never read, and how much gets repeated in several places across the world because the various groups are unaware of each other's existence? This is where conferences can be very advantageous - by putting people who are working on similar things together, in one place, it is much easier to become aware of who in the world is researching what.

More information is not necessarily better, but more information is what we are getting.

According to the fount of all knowledge  -  Wikipedia ;-)    - the only three countries not to have adopted the System Internationale units are Burma/Myanmar, Liberia and the United States of America. 

I can't help thinking that there is something deeply significant about those three countries falling into the same group, but I can't quite put my finger on it.

One of my big thick first year university physics text books has in large red writing on the back cover - "Not for sale in the United States".  I assume this is because of the SI unit issue.  I also assume it will be hard to find this book in a bookshop in Monrovia, though I haven't tried looking for it there.

As any physics student knows (or should know), units are important things. By 'unit' I mean a measure of the kind of quantity you are dealing with. So if it's mass, then a kilogram, a gram, an ounce, etc are all units;  if it's distance, then kilometres, light-years, feet are all units.   Units are essential - it's not very helpful to say that the distance from Hamilton to Auckland is 130. If I had a dollar for every time I've had to yell 'UNITS' at a student  who has missed them out, I'd be ... well, maybe not a millionaire, but at least able to affford one more cup of coffee a week during term time.

 Units are very useful too.  Last week I was trudging through some pretty intense algebra for some of  my research work. The potential for mistakes is huge, and it's difficult to be sure you get the right answer out at the end. (It's research, which means, amongst other things, you can't go and look up the right answer in a text book - it's up to you to work through it, and to know that you have worked through it correctly.) Units help in this process because when you have an equation, the units (more formally, the dimensions) must balance. Here's a rather trivial example. 

The distance a ball falls when in free fall is given by the equation s = g t^2 / 2 (g times t squared, then divided by 2). Here, distance is denoted by 's', time by 't', the acceleration due to gravity by 'g'. Let's check the units. On the right-hand side, 'g' is an acceleration, so would carry the SI unit of metres per second squared.  't' is a time, so would carry the unit of seconds (in SI). And 2 is just 2. No unit there. So on the right hand side we have

metres per second squared, times seconds squared

which is of course just metres.  And that matches the unit of the left hand side, which is a distance. That example isn't too taxing, but when you get nasty equations that need manipulating and solving it is a very good check that things are reasonable. (Of course it can't be used to spot all mistakes - if I'd written s = g t^2 / 3, this method wouldn't have picked up a problem.)

   Well, last night's thunderstorm was a bit of a feeble affair after the fireworks of Wednesday. There were a few flashes, the odd rumble, and a bit of rain, but it cleared away after an hour. Maybe somewhere else got the drenching this time. Still, it makes four days in a row of the same daily weather, almost hour-by-hour. And this morning....is shaping up the same way...

A student of mine sent me these photos of his television screen on Wednesday night (used with permission).  There was a lightning strike close to his house, which seems to have magnetized the television.  The picture is there, but the colour is wrong.

In an old CRT television, each point on the screen contains a phosphor - and there are three different colours, red, green and blue. To make up the colour picture, the phosphors are stimulated by the required amount, by a beam of electrons that hit the screen from behind. The beams are scanned across the screen using magnetic fields (charged particles like electrons are bent by electromagnetic fields), and, in order to hit the right phosphor, need to emerge in the exactly the right direction.  What I think has happened in this case is that the lightning has permanently magnetized some part of the television. This is hardly surprising given that lightning carries a huge direct current, and consequently creates a nice magnetic field around it.

So as the electrons pass, they are bent slightly but consistently off course, and hit the wrong colour phosphor. Hence the image looks right, but just with the wrong colours. De-gaussing  the TV removed the colour shift, putting it back how it should be.

Well, those of you living in the central North Island will probably have some idea already of what I'm going to say, but, for those of you who don't, I'll start by saying that the weather here has been rather predictable this week.  We've had three tropical-style days in a row, with a fourth shaping up the same way already.

It goes like this.  6.30 am Wake up to a beautifully clear morning, temperatures perhaps slightly on the cool side, but not a cloud to be seen.   9 am. Beautiful morning, nice mild temperatures. 12 noon. A few clouds around, getting warm.  3 pm. Uncomfortably warm and hot  6 pm.  Yukky sticky feeling to it.  Watch those clouds build. 7 pm or so. Thunderstorms start, along with the rain.  9 pm (or later, as it was last night) Thunderstorms begin to fizzle out.    Not sure what it's like during the night, but its nice and clear again the next morning.

Last night's thunder was particularly impressive, if that's the right word.  It went on for about three hours, with the sky almost constantly lit up by lightning flashes. And lots and lots of rain. The house remained nice and dry, but some of the buildings at the university haven't - there's a very damp smell pervading the corridor at the moment and I hear rumours of some offices down the corridor from mine being flooded.

This weather is more reminiscent of the tropics. I've only spent a few days in Singapore, but pretty much this is the pattern of events that unfolds there most days.

Here's a nice piece of applied physics research that will excite a significant minority of the population - specifically those who dread going to the dentist. Personally, I have never had any issues with drills (needles are a different story), but I know lots of people who do.

The proposed method uses cold plasmas to kill off bacteria-infected dentin that would otherwise have to be drilled out before a filling applied. A bit like microwaving the tooth. It's in the reasonably early stages of the commercialization process, but maybe you will see it at your dentist in a few years' time.

Read for yourself on the physicsworld site at  http://physicsworld.com/cws/article/news/41506

Now, what would be really exciting is if they could develop a method for taking blood samples without sticking sharp metal objects into one's veins. I would invest in that one.

The comment on my previous entry raises a few  issues with the way we feel heat.  (NB for those who normally read this blog on http://www.sciblogs.co.nz , you'll need to go onto physicsstop to see the comment - http://sci.waikato.ac.nz/physicsstop ) 

How hot we feel has more to do than just what the temperature is.  Anyone who has stood outside in a gale will know that it feels much colder than what the thermometer reads. That's the windchill.  The temperature is the same, but the rate at which heat leaves your body is much higher when the airflow past you is greater. That's because in still air, your body heats up the air around your skin, so unsurprisingly it feels warmer to you (because the air next to your skin really is warmer). But in a strong wind, that warm air is just blown straight away.

Humidity plays a key role too. Water requires energy to evaporate, and it takes that energy from what it is in contact with. So when sweat evaporates, it cools the skin. It evaporates more readily in low humidity conditions, so here it takes energy from you at a greater rate than in high humidity. Thus a dry heat might feel more tolerable than a wet heat.

Evaporation is what makes you feel cold the second you step out of a swimming pool, especially in nice sunny weather. All that water on you starts evaporating, and it sucks heat out of your body. So there's a vicious irony here - when you jump in the swimming pool to start your swim, it feels cold (water is better at carrying heat away from you than air), and when you get out of the pool at the end of your swim, it also feels cold.  Why can't it feel warmer both ways?

Writing the last piece about fridges has reminded me about a comment I heard from a fellow student while I was an undergraduate. I can't remember the exact circumstances, but it quite possibly had something to do with objects in liquid nitrogen.  Anyway, the comment was something along the lines of 'The temperature's so low you can feel the cold radiating from it'.

Hmmm. Yes, we know what you mean, but it's not quite right, is it?  It is heat that radiates. Hotter things radiate more. Cold is the lack of heat.   If we hold our hand close to something very hot, we can feel the heat radiation. But the hot thing isn't the only thing that's radiating, our hand radiates heat as well. What matters is the difference between the heat it receives and the heat it gives off. In my office at the moment, my hands feel to me neither cold nor hot, because what they are pointing at (namely the keyboard) is pretty well the same temperature as my hands themselves.  The amount of radiation arriving on them is roughly balanced by the amount leaving.

So when we 'feel the cold radiating from something', what we are feeling is that not enough heat arrives on our hands to balance the heat that is leaving. (Plus probably we are feeling the cold air too, due to convection currents).

But, before I treat my fellow undergraduate too harshly here, I should point out that physicists are quite adept and speaking about the absence of something as being something itself.   When we describe semiconductors (e.g. silicon, as in chips), we talk about n-type and p-type material. 'n' stands for negative, and in n-type silicon we consider electrical conduction happening because electrons move. That is a conventional way to think about electrical conductivity.  But in p-type (p is for positive) the mechanism for conduction is slightly different - we talk about the moving of positively charged holes.   A hole is really the absence of an electron, but we can treat a hole as an entity itself - even to the point of assigning it a mass. It's a bit like those slidy puzzles - slide one tile into the square gap to create a gap where the tile was - the gap (hole) appears to move, though of course it is really the tiles (electrons) that do the moving. When you've worked with semiconductors for a while you can forget that a 'hole' isn't a real thing.

So is it then really wrong to say you can feel the cold radiating off something?