Physics Reviews (A level)

Hello, I'm back to writing after I don't even know how long. I think it's been about half a year. I've been thinking I needed to get back into my reviewing, mostly related to my revision, and what better way to get back into it than having a test tomorrow. This review is on all the turning points stuff we've done so far. This relevance of this review on other Physics A-level students at other schools does depend on what the optional module the school picks is, as I think there's a bunch of choices, like astrophysics and (*retches*) more mechanics. Although this whole story probably won't be relevant in a few years anyway, as the spec and our understanding of science changes. I guess this makes this a little time capsule of Physics understanding at this current time (7/11/2022). Hello future people! How is life? Are people still discriminatory or ignorant in the future? So is the world as a whole actually not shit? Or did the right take over? Maybe we're all just dead.

Actually that last point (about a time capsule of physics) is quite relevant to Turning Points, as it is all about history of Physics. This makes it kind of interesting, as some of the stuff we have to learn has been disproved. The topic is also quite different to the rest of Physics, as that is very maths based with a fair bit of content to learn, whereas this is like the opposite. Anyway, I'll get on with it.

First up we have about Newton, which as we all know made lots of important discoveries in Physics (e.g. laws of motion). However, in a shocking twist, the part we're about to learn was something he actually got wrong 😱. This was during the long-lasting debate about light being a wave or particle, and Newton sided with the particle argument.  His theory was that there were light particles, which he called corpuscles, and there were 7 types, for 7 colours (we still often use these 7 colours, e.g. with rainbows (who knew Newton invented queerness?), but not really in physics, or to do with wave-particle duality). As we know, light performs different phenomena, which Newton needed to explain how light being a particle explained. 4 phenomena that needed to be explained were shadows, reflection, refraction and diffraction. Shadows could be explained as the particles would bounce off an object, meaning the light doesn't reach the other side, and similarly reflection was explained as the corpuscles bounce off the reflective surface at the same angle it hits. He explained refraction by saying the corpuscles are pulled through the material (by attraction) and speed up, causing the angle to change (we know this one isn't true, as light actually slows down in a more dense material). The one he couldn't describe however was diffraction.

Huygens was another scientist, and he disagreed with Newton, saying light was in fact a wave. They were direct nemeses, with a stronger arch-enemy story than ever Batman and Joker, The Rock and paper, Walter White and Cancer. It was a bitter rivalry, that ended only in a private fight-to-the-death on a boat in the middle of the pacific in 1822. No one within a 50 Megametre radius survived, as there weren't any cameras back in those days, not even black-and-white ones, no-one can truly say what happened. All that anyone knows is that 2 skeletons were found next to the sunken remains of the ship. Did they both kill each other? Was it like Romeo and Juliet, where one of them kills themselves and the other one finds the body so kills themself but then it turns out the first person faked their suicide but then they see that the second person is dead so then they actually kill themself for real? Or did they both reconcile, fake their deaths and fly into the sunset, hands embraced. Only those 2, God and fan-fic writers can truly know.

Oops I wrote so much I needed to start a new paragraph. So Huygens said light was a wave, but even his description was different to our view of light waves now. He said light was a longitudinal wave (uh oh), and that it propagated through the 'Ether', which was described as a mysterious force. This sounds kind of cool, but it isn't a very scientific way to describe light being a wave. Something tells me he couldn't think of anything, so just said it was mysterious🤔. Some things he said which are still believed today are the use of wavefronts, and that light colour depends on frequency. His theory also explained some things Newton couldn't like diffraction. He said that when a wave goes through a similar-sized gap, the wavefront spreads out. It also describes reflection, as the wave reflects off a surface at the same angle, and refraction (better than Newton), as a wave slows down through a denser medium, causing the angle to bend. However, this theory doesn't explain shadows, as the wave would be able to curve around the object.