Astronomy Conference on Gravitational Waves, Warped Space and General Relativity

A few days ago, Jack, Oki and I went to the first of two public lectures being run by the International Conference on General Relativity and Gravitational Waves. The world-renowned Kip Thorne from Caltech gave the first talk, and I thought I'd tell you a little about what he said.

First of all, Prof. Thorne talked about all the evidence that has been gathered which supports the Theory of Relativity. He told us that the farther out in space you get from a heavy body, such as the Earth, the more time speeds up. A clock running on a satellite high above the Earth runs a little faster than another clock down on the ground. As a result, car navigating machines (GPS's), would not work at all unless their clocks were adjusted for this time difference. This is an example of Einstein's Theory of Relativity put into practical use.

Next, he talked about the warped space surrounding heavy bodies such as the Sun. If only we could see the warped space, we would find that the size of imaginary circles around the Sun, compared with their diameters, would be smaller than pi X diameter. In the case of black holes, this distortion of space would be so extreme that the circumference of the event horizon would be tiny in comparison to its diameter.

The talk then progressed to gravitational waves, and their possible causes. Gravitational waves would come from supernovae explosions, spinning neutron stars, accretion discs around black holes, and even the left-over energy from the Big Bang itself. Each different type of event would have its own special signature of gravitational waves, and by recognising these signatures, astro-physicists would be able to work out not only what was going on in the universe now, but also what happened at the very beginning.

One slight problem ... we don't actually have sensitive enough instruments yet to be able to measure these gravitational waves. Various interferometers are being built around the world to help collect these waves, including one in America, one in Japan, another in Switzerland, two in Italy, and one almighty, huge whopper of an interferometer in Australia. Once these instruments are all up and running, we should be able to start collecting data. With more sophisticated interferometers, which they are hoping to develop by 2014, we should be able to get a very good picture of the history of the universe, and its general structure. Astrophysicists seem to be pretty sure that the universe we live in is a three dimensional membrane in multi-dimensional hyperspace! The gravitational wave research will give us a better picture of this theory.

Within the next thirty or forty years, astrophysicists are planning to build a giant interferometer in orbit around the Sun, shaped like an equilateral triangle, with sides five million kilometres long! An instrument of this size will be able to measure the gravitational waves emitted from the first moments of the Big Bang, and hopefully, we will then know how the universe really began! At present, we can tell what happened after the first 100,00 years, but we don't know what happened before that, although there are plenty of theories.

That's about all I can remember from this first talk. The next talk is in two days' time, and will be given by Sir Roger Penrose, the great mathematician. I can't imagine how he will be able to put his maths into layman's language, but if I understand what he says, I will report back to you with a description of his talk in a couple of days....

... Well, a couple of days have now passed, and I've just come home from the second talk. Sir Roger Penrose seems to be a modest, humble, down-to-earth, nice chap, and I like him, and respect him for his brilliance, but I wouldn't recommend his lectures. He seems to be one of those university professors who knows a lot, but just can't explain it to his students. In typical British fashion, he avoids modern technology, and prefers to use the old-fashioned overhead projector and hand-drawn transparencies to the computer PowerPoint slides, which make it harder to understand what is written.

He rambled in a disorganised fashion from one transparency to another, and never actually told us what he was really trying to say. However, I attempted to gather a few points, and this is what I think he meant, although I'm probably wrong: there was a number which was bigger than a googleplex! Bigger than 10 to the power of 10 to the power of 100! It was 10 to the power of 10 to the power of 125! I'm not sure what that number was connected to, but I briefly noticed protons and neutrons written below the number, and I think the enormous number estimated how many protons and neutrons are present in the universe.

The talk was supposed to be about what happened before the Big Bang. He mentioned briefly that there was an asymmetry at the beginning. He also said he thought it might have been possible for time to have existed before the Big Bang.
Then he talked about the end of the universe. All matter would decay, after a terribly long time, such a long time that it would be very boring to hang around and wait for it. Then black holes would evaporate after an even longer time, going pop when they died, and letting out some low energy photons in the process.

He then said that after all the matter in the universe had decayed, and all the black holes had evaporated, all that would be left were photons, still travelling at the speed of light, and experiencing no time. The universe would end in a timeless, massless state.
However, Sir Roger also believes that at the end of our universe, a new one might begin when the remaining gravitational waves crash in on each other and create an imbalance that ignites a new Big Bang.

This may, or may not, be what the talk was about. I'm still not sure. However, it was good to see such a famous scientist in the flesh, and I'm glad I went to the lecture. If you asked me which talk I enjoyed the most, it was definitely Kip Thorne's lecture. I learnt something from him.