Tuesday, March 14, 2006

An enjoyable weekend back in BJ with a heady mix of work and play.

Firstly a report on the state of play of all my research...ever.

I think that this is probably a regular theme in the research of a theoretical physicist.

1) Think of an idea, be it groundbreaking or just a minor extension of somebody else's work.

2) Read the relevant papers - a lot of papers are written in a very short format missing out most of the calculation. This means that you have to make all the mistakes that they made in getting to the final answer. The difference is, you know when you've got it right because you have the answer sitting in front of you - or so you hope. The number of papers that are simply wrong is remarkable.

3) Start playing with the equations. Get used to the calculational tools and learn where they break down and where they are malleable.

4) See a clear path from the start to the final outcome and have a rough idea of how you will write the paper. You may be able to see a couple of minor stumbling blocks but they shouldn't be a problem.

5) Minor stumbling blocks turn out to be a major problem. This either spells the end of this project and tells you why nobody else has done the calculation or it's an interesting inconvenience which will teach you something in the process of overcoming it.

6) If you continue, you will get over the obstacle and see the light at the end of the tunnel. Finish the calculation and sit back, go home and go to sleep.

7) Wake up sweating in the middle of the night realising that a simple assumption you've made makes no sense at all. Somewhere in your calculation you've accidentally calculated that the universe is made of cellophane, the world is flat or nothing exists at all.

8) Get into the office and start all over again.

9) Repeat steps 6 through 8 until you're so blind to your own research that you no longer notice the blindingly obvious mistakes.

10) Write up the paper and repeat steps 6 through 8 several times for good measure until you've used up a redwood's worth of paper.

11) Submit paper to the web.

12) Repeat steps 6 through 8 but don't tell anyone that what you've put online has a huge flaw in it.

13) Replace paper in the middle of the night when nobody is looking.

14) Continue step 7 until step 1 is repeated and you can start again.

I'm currently running through steps 6 through 8 for the second time on the current paper. This means that though I should be able to write up tomorrow, I know that there is probably a long path ahead.

This means that I've been in the office over the weekend and when I haven't been in the office I've been seeing friends and talking physics.

So away from physics, I sampled my first home-made hotpot meal at a friend's house which is something that I'd like to try back in the UK.

Take a large pot and preferably an electric heater. Heat up some broth, be it oil or water based in the pot but make sure it has lots of flavour. Then for the next few hours, throw in bits of meat, vegetables, tofu and whatever else you fancy into the pot to cook for a few moments before dipping it in a sauce of your choosing and eating. A nice, casual dinner party meal for a few people. Like fondu, without the cheese and with a much bigger pot.

During the meal we watched three movies. The first two were short films taken from full length versions by Asian directors Fruit Chan and Chan Wook Park, both notorious for their extreme subject matter and Park specifically for his obsession with tales of revenge. Fruit Chan's film, Jaozi (meaning dumplings) is an exceedingly strange film essentially about the image consciousness of the Hong Kong fashionistas. I shall not reveal the contents of the dumplings on this blog. If you want to know, there are the usual places to find out everything you ever wanted to know about movies. (Incidentally the IMDB has now been on the web in some form for an impressive 17 years!).

Park's film is again a revenge story with a catch-22 element and some interesting twists. About the innocence of an easy life, though pretty gruesome, it includes enough surreal slapstick moments and cunning twists to raise it above a simple thriller. Both these films are worth a watch if you're into Asian Extreme though I get the impression from reading around that a lot is lost in the short film versions.


Complete change of topic....

I was involved for a couple of summers in the development of ATLAS, one of the detectors for the LHC, the particle accelerator planned to begin running in 2007. I've spoken about it in some detail before and it's not what I want to write about in detail now. What I do want to point out is that it's a stupendous feat of engineering and scientific expertise (something that I had a truly microscopic part in and so make no claims to have added anything to the impressive nature of this monstrous creation - I helped to program a calibration system which works out how the central detector changes shape over time so that the exact position of the particle collisions can be calculated).

The point is that the accelerator is by far the largest machine ever built and ATLAS is by far the most complex - it's essentially a five story computer/detector with sections cooled by liquid helium, many hundreds of thousands of miles of wiring and designed to deal with 40 million beams crossing each other at effectively the speed of light every second. Not only this but it needs to make decisions about every one of these crossings before the next one comes along. It's taken about 15 years to build this thing and there's a lot riding on it. In fact there's the future of high energy physics riding on it. If this thing doesn't see anything, a lot of us will be out of a job, science funding would be slashed as physicists had spent four decades barking up the wrong tree. We're expecting to see a whole zoo of new particles here which will answer a lot of the questions of the last 20 years of research - we hope. Anyway, the reason I mention it is because it's big.

In fact what got me thinking about this was Paul Cook's blog where he wrote about the discovery of a planet only five times the size of the Earth circling a nearby star, the point being that the viewing this planet is like seeing an object the width of a human hair, on the moon! Since the invention of the telescope and the discovery of the moons of Jupiter we've come an immensely long way. We do however have a lot further to go.

He also mentioned LIGO which is a piece of technological wizardry similar in magic to the LHC and ATLAS. Imagine putting on a pair of headphones which allowed you to hear two black holes colliding somewhere in our galaxy along with echoes from the big bang - not just the ever popular but somewhat troublesome microwave background radiation that permeates the universe - that's from a slightly more recent era. LIGO hopes to be able to do this but rather than using sound, it will use gravitational waves. There is a problem with this however as gravitational waves are ridiculously weak. The effect they have is to warp space time...a bit. Really, just a bit. In fact LIGO needs to be able to detect when the distance between two points which are several miles apart changes by one hundred millionth the width of a hydrogen atom. THAT'S JUST PREPOSTEROUS!!! What's even more preposterous is that we think we can do it. The thing is running, taking data and getting more and more accurate readings all the time. We haven't spotted any black hole collisions yet but we think that they will be seen. This is another giant leap in our slow but sure emergence from blindness that we call scientific progress. Exciting times ahead

As you can probably tell from previous posts, I have a bit of a thing about extremes of design and engineering and being in Beijing I get to see a great deal of fast, if not safe, skyscraper construction. The Taipei 101 tower is currently the worlds tallest building at just over 500m, much to the chagrin of the Chinese. They don't like this runaway nation to have anything better or bigger than it and are already building a structure in Shanghai which will be taller than 101, just. But neither of these buildings are anywhere near the height of the Al Burj and the Burj Dubai which are planned to be around 800 m tall. The Dubaians have a habit of building the biggest and best having completed by far the world's most expensive hotel last year (though apparently they forgot to sound-proof the luxurious rooms). In fact these two buildings, one of which is planned to be finished by 2008 are not only tall but, in my opinion, pretty stunning monoliths. Frank Lloyd Wright planned and designed in detail a building which would be a mile high and the Japanese still consider building a 4km high pyramid with it's own weather system to create an entire, enclosed city.

This talk of extremes brings me nicely onto today's seminar by Prof Ronald Fox from Georgia Tech whose talk was titled 'A physicist's perspective on the origins of life'.

He started off pointing out that what we would call astronomically large numbers (eg. the number of protons in the universe, about 10 followed by 80 zeros) are actually tiny when we start talking about combinatorial numbers. Combinatorial numbers means given a certain set of objects and a set of rules for how to arrange them, how many distinct (or indistinct) possibilities there are for the arrangements. For instance there are about the same number of combinations of choosing 50 balls from 100 as there are protons in the universe. If you want to come up with big numbers, don't look at the cosmos, look at simple combinatorics. In fact if you want to get into numbers larger than even these combinatorial numbers (and of course you can get any size number you want with combinatorics, the point is if you want to calculate combinatorics that have anything to do with the universe you are marginally bounded), you need to follow Turing's arguments about computable numbers which is really well explained on this page.

Anyway, getting off track again. So combinatorial numbers are big and it has been pointed out that the number of possible amino acids given a certain number of base pairs is so ridiculously large that the probability of having the set that we seem to have is essentially zero. So life shouldn't exist.

It's sort of an anthropic principle based on rather weak assumptions about the nature of amino acids.

Ronald fox disagrees with this simple argument and I have to agree with him. The lecture was showing how you can take a relatively simple route using energetics rather than combinatorics to show that any rocky planet with similar conditions to Earth is likely to produce the same form of RNA that we have on Earth. You can show this starting with the abundance of the important elements (of which there are only a dozen or so), necessary for life. From this you can show that monomeric organic compounds are likely to form using simple chemical arguments. From this it is again simple to show that given a fair range of conditions: some heating, or pressure waves etc. you will almost certainly get polymeric organic compounds and they will be the same whatever planet you have as long as the physical laws in all parts of the universe are similar to here. His arguments follow a similar though more complex line through to the construction of RNA, concluding that this is an almost inevitable product of a rocky planet with conditions similar to ours. His theories are not proved (or indeed proofed) but Francis Crick agrees with his reasoning and it seems pretty reasonable. NB. My organic chemistry is pretty poor so the above may well have mistakes - the basic outline is however correct.

The point is that you can get a long way with the origins of life just using arguments of energetics and some assumptions about the physical and chemical laws of the universe (which seem pretty reasonable and even if they're not, they're pretty firmly fixed within our galaxy which has somewhere around 10^11 sun-like stars).


Anonymous said...

A great post John. Had me roaming all over the web in my lunchbreak. I think we share the interest in extremes. Incidentally, your Wikipedia link to The Illinois is bust. Here it is in full: http://en.wikipedia.org/wiki/The_Illinois

Keep up the good work Biscuit.

Unknown said...

Cheers Bill,

Pleased if I can enthuse others a bit! There's lots of frankly mindblowing stuff going on at the moment and it's fun to share it with appreciative readers. Thanks also for the link, now hopefully fully functional.

All the best,