illuminating science

Well, everyone’s blogging about it, so I have to chip in. Recently announced, scientists have found an Earth like planet only 20 light years away, and in the so-called “habitable zone” of its star.

Basically: By studying the motion of star Gliese 581 in the constellation Libra, astronomers were able to detect a planet with about 5 times the mass of Earth (about half as big again in diameter). Models suggest that it’s made of rock, quite similar to Earth. But most significantly, it’s at the right distance from the star for its surface temperature to be between 0-40 degrees - just the right temperature for liquid water, a requirement for life as we know it. Interestingly, the star is a red dwarf, a relatively cool slow burning star. This new planet is much closer in to its star than Earth is, but becase the sun is cooler, it doesn’t get fried. There’s no guarantee that the planet does have water, let along life, but at the very least it’s the first planet discovered which really ticks all the boxes.

I’ve got to say, I can’t help but be excited by this. There’s a potentially habitable planet among the 100 closest stars to Earth. Sure, it might just be chance - but if there really are lots of planets like this out there it really ups the argument for extraterrestrial life! It also means (and here I’ll be very speculative) that this planet could be the target of extra-solar exploration. Sure, this is a long way off (bets, anyone? I’d be surprised if it was within 100 years - maybe 200 as a ballpark figure?) and the logistics and travel time are enormous but 20 light years with a defined target makes it just a little more possible, I feel. Of course, I’d kind of like to get our own planet in order first…

Anyway, the book makers have already shortened the odds on alien life, so we must be getting closer!

Powerpoint is the Big Thing at the moment - talks are all done with Powerpoint slides accompanying, even lectures and school classes are now often done with Powerpoint. But new research from UNSW suggests that having the same text on your Powerpoint slides as what you’re saying may actually limit the audience in what they can learn. Apparently our “working memory” is really only good at handling two or three tasks at the same time - if it tries to listen and read at the same time, it’s got limited space left for actual thinking and processing.

They suggest that diagrams and pictures on slides are fine (since these present the information in a different way) but using text detracts from the rest of your talk.

I’ll have to think about this a bit more - I do like having some text on the slides so that if I tune out for a few seconds (minutes…) I don’t completely lose the plot. But I definitely don’t write all my text on there (and read verbatim - very, very bad). On the other hand, when I first started giving talks, I preferred to use no slides - I liked people not to be distracted from what I was saying by reading ahead (or behind). If this research really does hold water, I’ll have to think more about my own presentation style.

Another point they make is that students learn more (in a talk, anyway) from being presented with worked solutions - so their brain can devote itself to understanding and remembering, rather than solving. I’d certainly like to see more of their research first though

Well, my grandma’s been in intensive care this week, which has been pretty stressful. It’s all okay at the moment, although she’s going on dialysis this morning. I confess, though, there’s a part of me that find the whole thing “interesting” in a strange way - so many machines, so many different drugs all working together, so many talented doctors. Of course, I’d be even happier if it was a sarcastic doctor with a cane treating her. (That’s a TV reference I hope you know!)

Just wanted to put this quick post up before Easter - hope everyone has a good break.

Just reading a neat paper on changes in length and time scales under special relativity. The idea of length (and time) scales is an important one in physics - it’s about asking what sizes “matter” to your system. For instance, is it a galaxy, thousands of light years across? Or is it an eyeballs, where millimetres is important? Or is it an atom, where we need to consider billionths of a metre?

It’s not just for fun, though - it helps you work out what’s important in your problem. If what you’re interested is on the scale of light years, you don’t need to worry about atoms. If you’re interested in how plants use photosynthesis, most of the interesting stuff is over in a millionth or even a billionth of a second - so don’t worry about leaves waving in the breeze, or maybe even the motion of certain proteins.

And of course, one place all this is really important is in computation - simulating physical systems on a computer. After all, if you you’re interested in how leaves blow in the wind, there’s no point in taking snapshots of your virtual plant a billion times a second. Save time, and just take 30, or 100, calculations “per second” of plant time. On the other hand, if you’re interested in how energy moves between different molecules, you’re going to need to simulate a much smaller scale and on much shorter timescales.

That’s one of the things that makes biology so hard to study - you’ve got “interesting” things happening on the scale of seconds, thousandths of a second, all the way down to billionths or trillionths. And sometimes, there’s things happening on much longer timescales as well! If some process takes 10 seconds to happen, but you need to increment in steps of 0.0000000001 of a second, it’s going to take a very long time! Similarly for distances - if I need to simulate every molecule of a plant, it’s physically impossible on any computer we have to do this before the sun runs out of fuel…

Enter this paper. In special relativity, time and space can change depending on how fast you’re moving. Clocks can run slower when they speed up (tested with airplanes!), rulers can appear shorter, etc. The upshot of this is that the important lengthscales and timescales can also change - if you simulate your particles moving very fast, you might find that you can be more “pixelated” in your model, and still get all the info you need. Everything kind of gets “compressed”, if you like. This means that choosing a different speed for your simulated experiment can cut a week long calculation down to just 30 minutes!

Apparently, other researchers are so impressed because no-one had found this before, despite special relativity being very well understood (by some ) It’s a simple discovery, in essence, but it might make previously impossible calculations very realistic - and who knows where that will lead?