Fat balls

OK, so this is not tenuous exactly but it is kind of convoluted. Bear with me.

At the weekend I bought some of those fat balls for the birds. I'm not sure why they like them - because I'm not sure that fat is a regular part of their diet - but I like to feed them, so that's why I bought them, and on Sunday the Minx put three of them in the feeder.

When I was making the coffee this morning I glanced out of the window and there were two birds busy pecking away at the balls. That'd make a good picture, I thought, so I went to take a photo. Obviously as I moved near to the window, the birds flew away, but I figured if I stayed still and waited a while they'd come back. They didn't.

And this act of affecting something by observing it put me in mind of a mind-blowing physics experiment whereby a beam of light is shone at a screen. There are two slides which can be placed in front of the screen: one with two slits in it and the other with just one. Depending which slide is in place, a different pattern is formed on the screen because, in the two slit scenario, the photons coming from each slit interact with each other, creating a more complex pattern . So far, so straightforward.

Here's the interesting bit. If you 'slow' the light beam down until it's emitting just one photon at a time, the photon falls on the correct pattern depending on which slide is in place. Which is odd, because in the two slit scenario, the pattern is formed because the photon interacts with other photons. But in this version of the experiment, there are no other photons: we only have a single photon. Yet even though this single photon can travel only through one slit, it 'knows' whether the other slit is there or not.

That sounds crazy, right? So crazy that it can't be true. But it is. Absolutely 100%, scientifically verified to be true. And this is because, until we observe them, the photons are not actually in existence: they are probabilities. And when there are two slits, those probabilities interact. Yet these photons are an actual part of our physical universe.

If you've followed this - and especially if you've not heard about the phenomenon before - then I think this SHOULD be the most mindbending thing you've ever come across. It's certainly stranger than anything we've ever imagined or that I've ever read in any book, probably because it's so unintuitive. When I learnt about it, it changed my life. It made me realise that the universe that we were born into is strange and marvellous, and contains truths that we will never grasp intuitively because the world we experience is so different from the relativistic and quantum worlds that are extreme extensions of it. 

And I love that, this truly weird world of physics; harder to believe than any legend or myth. I wish we all were more excited about it.