My head hurts when I think about the Big Bang – the moment when the universe started. How did something come out of nothing? Is there a beginning to time? Is there a multiverse? Well, I didn’t quite get the definitive answers to these questions when I attended a lecture by Professor Andy Parker, the head of Cambridge University’s particle physics department, but I did learn what the Big Bang sounded like!
Apparently, the sound can be extracted from the cosmic radiation that has been with us since the Big Bang. I was expecting to hear the most dramatic explosive noises, but it sounds more like a robotic hum. It’s a bit disappointing, actually. You can listen to it here.
Aside from the sounds, I also learnt about dark matter. It turns out that the normal matter – the stuff we can see and observe – only makes up 5% of the universe. Dark matter makes up 25% and dark energy makes up the remaining 70%. So the world we see whether through microscopes or telescopes are only a tiny proportion of what exists.
Dark matter does not interact with observable electromagnetic radiation, like light, and so it is very difficult to detect. In fact, it’s only through the fact that galaxies hold together that first prompted scientists to think about dark matter. The observable normal matter would “generate” enough gravity to hold galaxies together, so there must be some other type of matter (and a lot of it). That’s where dark matter comes in.
As for what dark matter is, no-one is quite sure. Some think it could be tied up in brown dwarves (something between Jupiter and a star) or massive compact halo objects or MaCHOs (don’t ask). But the more likely explanation is that it is made up of some unknown fundamental particles.
Don’t even ask what dark energy is. The main message is that most of the universe is made up of stuff we can’t observe, we don’t really know much about this dark stuff and I get a headache when thinking about what happened before the Big Bang.
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