Strings 2006

One more day of the Strings 2006 conference to go! It’s been a very intense conference, with many ideas and talks. I’ve gained some ideas which are at least somewhat related to things I’ve been thinking about, but I’m not sure how they’ll turn out.

I have been a little disappointed that there have been no “big picture” talks — string theory has had a slow year, and I would have been interested to hear what some of the big names were thinking about for the coming year. Though I suppose if anyone did have a big idea, they would have already published.

I’ve been contributing a little to Jonathan Shock’s very ambitious efforts to summarise proceedings at the conference, over at his blog. It’s turning into a useful reference (judging by his page hits, if nothing else), and it’s certainly be useful for me to review the talks. Though it is hard trying to write down succinct summaries of talks in other areas of string theory, especially when there are 5.5 hours of talks a day!
Continue reading “Strings 2006” →

Apportioning the Internet

The control of the infrastructure of the Internet is a controversial issue. Recently in the news was the refusal of ICANN, the governing organisation of the domain name system, to approve an application for the creation of a “.xxx” domain — aimed at sites providing pornographic material. The issue is deciding just who actually made the decision. But it’s definitely not the only issue of global fairness in Internet infrastructure.

The problem is that ICANN makes domain name decisions which are then effectively binding on the world (though China may be thinking of breaking ranks). But in general, the rest of the world has to follow suit if the Internet is to continue to work smoothly.
Continue reading “Apportioning the Internet” →

ANALYZE your PostgreSQL databases!

I’ve recently been reminded, in no uncertain terms, of the importance of running the “ANALYZE” (or “VACUUM ANALYZE”) command periodically on a PostgreSQL database installation.

My problem:
Amongst other tables, a production database I administer has three tables: two moderately large tables, A⁽¹⁾ and B, and one quite large one (>700 000 records), C (for “Cross”), which is essentially the full cross product of A and B, with an additional piece of information for each tuple (record). So I’m associating some information with every combination of records from tables A and B.
Continue reading “ANALYZE your PostgreSQL databases!” →

Extraordinary measurements

In the news today is the discovery of a planet about fives times the mass of Earth, orbiting a star 20 000 light years away from Earth.

That’s just amazing. Never mind the implications for the search for life, or any of that — the actual measurement is amazing. A quick back of-the-envelope calculation shows that an equivalent measurement would be observing something the width of a human hair, end on — about 0.05mm thick. It’s not easy seeing that with the naked eye more than about a tenth of a metre away, never mind on the moon.

Meanwhile, the people at LIGO are trying to measure changes in the path length of a ray of light, caused by passing gravitational waves, of less than a thousandth of the width of an atomic nucleus.

And the Large Hadron Collider, under construction near Geneva, will collide thousands or millions of protons a second, and track almost all of the vast numbers of particles each collision creates. We typically talk about atoms in groups of about 10^23 particles, but here we’re talking about tracking each individual particle.

And perhaps most amazing to me, we can make meaningful statements about the whole universe a tiny fraction of a second after the Big Bang, based on a few observations from a single planet in a single place in the universe, at essentially a single point in time in the universe’s evolution.

There are some really smart people out there.

$100 laptops — now what’s the next step?

It’s starting to look like Nicholas Negroponte, founder of the MIT Media Lab, might just make his plan for a sub-$100 laptop work. Yes, that’s one hundred dollars. It has some very interesting innovations, and makes all sorts of interesting ideas possible.

The laptop is being developed by a newly-formed foundation, called One Laptop Per Child (OLPC) — have a look at the official FAQ. The idea is to make a really cheap but very usable laptop, which will be bought in quantities of at least a million, by governments, and distributed to schoolchildren. The idea is no less than, well, one laptop per child, anywhere in the world.
Continue reading “$100 laptops — now what’s the next step?” →

Relaxation = information?

I’m addicted to high-information entertainment. Hey, so are most of you reading this. But it’s such a throw-away line that is ceases to mean much to us anymore. But I think I might really mean it.

I sometimes play the mental game, when I’m bored, of imagining what I would do if suddenly transplanted to times long ago. The immediate realisation is that while I have lots of good technological concepts, I don’t really know how to go about, say, finding iron ore or making those cotton spinning machines that were a part of the start of the industrial revolution. And even if I could take my reference material (ie. my laptop) along with me, I could spend my life trying to remember exactly how 1 volt was defined, so as to make a generator to power it.
Continue reading “Relaxation = information?” →

Asymmetries in scientific fields

I’ve just finished reading Michelle’s candidacy report, on some of the research she’s been doing into catalysts for certain reactions in organic chemistry. It’s highlighted for me some of the differences between different fields of research — and in particular, between theoretical physics, and the more experimental work that most other people at Caltech do.

Michelle’s report was very easy to read. That’s partially because it’s well written, but I’d say it’s also because the difficulty is in a different place to that of papers that I’m used to reading. “Reading” a longish string theory paper can take literally months — and even then, I can’t claim to understand everything that is being said. Reading Michelle’s report took a few hours, and while I didn’t understand all the jargon, I think I got the gist of the issues and approach that her research took.

On the other hand, having read Michelle’s report has brought me no nearer to actually being able to synthesise anything more interesting than a bowl of pasta and sauce. “Reading” the string theory paper, however, has involved working through the mathematics behind each step, at great length — sometimes hours for a single line. So once I’m finished, I’ve done a substantial portion of the work that was required to write the paper in the first place. The analogy would be me reading Michelle’s paper, and then making some of the reagents too — and that would take months too.
Continue reading “Asymmetries in scientific fields” →

Upgrading my memory

I’m proud to present the Official Langabi.name guide to Adding 256MB of RAM (memory) to your laptop:

Turn off your computer. Open the relevant part of your laptop to expose the memory slots. Check that you have a spare (unused) memory slot.
Remember (correctly) the result of the above check.
Assuming the success of the above steps, order a 256MB RAM chip for your laptop. Sites like Crucial allow you to order the correct RAM for the exact model of laptop that you have.
Wait for the RAM chip to arrive (allow approximately 3 days for shipping and damage. Though hopefully not much of the latter).
Turn off your computer. Touch a metal part of it to remove any static charge you might have. Open the appropriate part to expose the memory slots, and insert the RAM chip. Close the computer again, and turn it back on.
Live in eternal bliss. Or at least until software becomes yet more bloated.

All this can be had for the low, low price of 102.988 Del Taco “Taco Tuesday” tacos*. Or, if you must know, $36.79.

But wait, you say — there are surely lots of far more complete guides (with pictures!) on buying memory, all over the internet? True, but they all leave off the vital step 2.
Continue reading “Upgrading my memory” →

Lines, intersections and dimensions

Building on the interest in my post on knots and different dimensions, I thought I’d say a few words on some interesting issues on lines in different dimensions, as raised by a recent seminar. It’s an interesting mind game!

We explicitly consider only generic situations from here on, which means that we ignore special cases as physically unlikely. So parallel lines need not be considered — all lines will have some random angle between them.
Continue reading “Lines, intersections and dimensions” →

The problem with point particles

Quantum mechanics is often viewed as a “weird” theory, with all sorts of non-intuitive predictions. However, there are more serious conceptual problems with classical mechanics, at least in its simpler formulations. One of these is what happens near point particles — in fact, point particles in classical mechanics lead to all sorts of infinities. I’ll say a little about this below, as well as talk about what quantum mechanics and string theory have to say about these short-distance infinities.
Continue reading “The problem with point particles” →