Friday, November 16, 2007

the darkness at the end of the paradigm

The other day we went to a very thought-provoking talk by Jocelyn Bell Burnell (the discoverer of pulsars) at the Bath Science Café at The Raven.

There was talk of dark matter and dark energy, which are basically 'dark' in the sense that no-one knows what they are. We do know that dark matter is probably non-baryonic, unlike most matter in the universe. (Baryonic matter is matter with protons and neutrons in the nucleus.)

So, she said, there will be a paradigm shift when the nature of dark matter and dark energy is discovered.

There was a similar paradigm shift when it was finally realised that phlogiston didn't exist. Natural philosophers studying burning materials assumed that, since they gained weight after burning, they must be emitting a substance that had negative mass; they called this substance phlogiston. Joseph Priestley almost had it right when he produced "phlogisticated air" (air that, he believed, was rich in phlogiston), but it was Antoine Lavoisier who realised that phlogiston didn't exist, and that rather than losing a substance with negative mass, the burning material was actually fixing oxygen out of the air. The theory of phlogiston may seem daft now, but it made sense at a time when it was assumed that air was all one substance, not several different gases mixed together. (I remember watching a video about this in O-level Chemistry.)

Another paradigm shift that Professor Bell Burnell told us about occurred in astronomy when looking at planetary orbits; it was assumed they were circular, but then people observed anomalies in them and called them epicycles, and it all got very untidy until Johannes Kepler pointed out that the orbits were elliptical.

And of course the most famous paradigm shift of all was the one when Copernicus pointed out that we live in a heliocentric solar system, not a geocentric one.

At least nowadays you are not likely to get burnt at the stake or kept under house arrest for suggesting a radical new scientific idea. The worst thing that could happen to you is loss of tenure.

The point of all this is to say that, although there is speculation as to what dark matter and dark energy might be, it may be that something else is wrong, such as the basic assumptions which led to the need to theorise their existence, in which case whatever is causing the need to insert them into the theoretical models turns out to be something completely different. In a hundred years' time, people could be laughing at those early 21st century scientists who believed in 'dark matter' and 'dark energy', in the same way that we find phlogiston, flat earth theory and geocentric cosmology amusing nowadays. Such is the weirdness when we're sitting on the brink of a paradigm shift. Maybe a bit like sitting at the event horizon of a black hole - nothing will ever be the same again once you have passed the threshold.


Joe said...

Science, like evolution may mostly go along in a reasonably smooth curve but sometimes there are huge jumps, or quantum leaps which redraw not only scientific research but the actual way we see ourselves as a species and the planet we live on. Only a few decades ago people were pooh-poohing the idea of continental drift and yet now we take the movement of entire continents and subduction of continental plates for granted. Dark matter may be one of the next leaps that makes us re-evaluate the world, or perhaps it will be the creation of AI, proof of life beyond the Earth, being able to massively extend our own lifespans... No wonder SF writers can get dizzy with imagination ...

Nice to hear Jocelyn is still lecturing, I remember reading about her when still at school and those strange, regular radio signals - could it be a signal from another race? Sadly not but it was still something strange and new we never knew existed; indeed until just a few years before her and her colleagues that entire view of the heavens via the radio telescope was something humanity had no idea existed all around it. Now we can go to a website and listen to the actual sound of the hydrogen band of the universe.

And still got a soft spot for Kepler; I read about him too as a schoolboy and also via dear old Carl Sagan's Cosmos. And I had that fine pleasure of using that knowledge to deflate a pompous twat two years above me at school, who demanded we stop using the computer (back when the school had only a couple of BBC Micros) because he and the physics teacher had a new programme to run on it which was more important than our work, a programme showing Kepler's theories which I wouldn't understand. Had the delight of watching his arrogant face fall as I explained the ideas of elliptical motion and his time with Tycho Brahe. That sort of thing rarely happens, but by god it was so satisfying when it did and confirmed for me that reading a lot is a good thing :-)

Yvonne said...

Deflating the pompous is always a good thing.

I'm looking forward to finding out where the next paradigm shift takes us. All this astrophysics is really exciting stuff.