A couple of posts ago I mentioned that stars shouldn’t exist – at least not by classical physics standards anyway. I skirted the issue at the time, but it’s high time for a closer look as I cant delve into any more details about nanotech OR the lifecycle of stars without covering some basic quantum mechanical phenomena – turns out quantum mechanics is actually pretty important as I’ve mentioned before.
First i need to more accurately describe the problem. Atoms, as you may remember from high school, have two types of particles squashed tight together at their nucleus; the positively charged protons and neutrally charged neutrons. (If you need a refresher and a laugh look here). Those positive charges are the central ‘problem’ in fusion, as they repel other positive charges and mean that nuclei will try to get as far away from each other as possible if left to their own devices, almost like a little ‘force-field’ around each atom. Yet for fusion to occur, these positive charges must not only collide, but stick together – and at the temperature of stars, hydrogen atoms don’t have enough energy to do this – so how does fusion occur at all?
Well of course, it’s not the star that’s wrong – it’s our human lack of experience with the nanoscale that causes the problem. Matter actually only appears as a solid when you look at length scales longer than a few nanometers, below that it becomes apparent that what we refer to as ‘particles’, like electrons and protons and photons, are actually something else entirely – they’re waves AS WELL AS particles: the so called ‘wave-particle duality‘. This wave nature allows particles traveling fast enough to pass through this ‘force field’, event though classically they don’t have enough energy to do so – they ‘tunnel’ though it. These little wave-particle things literally smash into one side of the barrier, and then occasionally appear on the other side, without traveling through the barrier itself. That’s the equivalent of driving a car into a concrete wall at full speed, and occasionally – just occasionally mind you – the car disappearing on one side and reappearing on the other completely unscathed. Bizarre.
And this ‘quantum tunneling‘ process is how stars are able to fuse hydrogen nuclei together to form Helium; how they’re able to shed that little bit extra mass and convert it into the glorious electromagnetic radiation that we bask in all summer long. Once the nuclei tunnel through this ‘force-field’, they’re captured by the nuclear strong force. (you may guess by it’s name that its rather strong. Stronger in fact, than that repulsive force between the positively charged protons, but only active over very tiny distances; over about 0.000001 nanometers. [and a nanometre is 0.000000001 meters]) And finally it’s that strong force that holds the entire nuclei together in its stable form of Helium.
So just to reiterate. It’s the fact that everything solid in our universe is actually comprised of waves at some ridiculously small length scales, that allows stars to shine. Some of the smallest and strangest phenomena in the universe dictating the behaviour of the largest, longest lived structures and , by association, all the diversity of life that has arisen as a consequence of them. All just a by-product of some tiny little waves.
And we’ve still only scratched the surface of the true weirdness of the universe – wait till you see what happens when you get stellar quantum-mechanical objects like neutron stars. Or entanglement. Or metamaterials.
The universe suddenly becomes a for more interesting place than we have ever dared imagine.
But, just to keep things in perspective, my next post is about dog feces, cockroaches and Girl-scout cookies. :p