I wrote this post at easter, and I’ve been meaning to post it ever since, but haven’t quite got round to it. I’m not really all that happy with it to be honest, but I’ve finally decided to resign myself to the fact that I’m not going to have the time to make it perfect until probably after my wedding… so here it is anyway. I hope you’ll at least enjoy the videos!
It was early on a cold Easter Sunday morning and I was in the car with my fiancée on the way to church. I was more excited than usual about going to church, as I’d given up eating meat for lent, and the church was celebrating Easter with a shared cooked breakfast. I intended to eat my body weight in sausages and was in a bouncy mood.
‘Oh, yes, also Josh – you can look in the back and find your Easter egg from my mum’ my fiancée said as we neared the centre of Ipswich. I reached back for the plastic bag and pulled out some decaf. coffee filters and a biography of Albert Einstein. Result! This morning was getting better and better.
In the event though, the breakfast was an utter disappointment. After 40 days of meat abstinence, I wanted the works; hot bacon, large sausages, salty boiled eggs, black pudding and – perhaps unreasonably – I was sort of hoping for some steak. Instead, for my £2 fee, I was presented with a luke warm coffee, some co-op muesli and a cold bacon sandwich.
The Einstein biography was much more appetising, and so later that day I decided a jaunt through general relativity might be a fun way to occupy myself during my few days off over the bank holiday.
One of the reasons Einstein was so great was because he looked at the hardest, and therefore I think the most interesting questions in the whole world. He was interested in what’s going on in the air around us all the time; the way in which all the different types of invisible waves buzzing around our heads work. What are they like, what are they really made of and how do they allow us to see, hear and tune in our radios? In this video clip, the amazing Richard Feynman talks about this crazy, complicated network of waves.
If we take Feyman’s example of waves in a swimming pool, surely the waves are not a thing, but rather a way in which the water moves? Einstein had a similar thought about light, if it’s a wave, what it is a wave in, exactly?
He eventually came up with the idea that Planks constant wasn’t just a mathematical curiosity, but a meaningful physical reality; it symbolised a particle of energy and it was these particles – we now call them photons – which were the matter which make up the light waves.
What’s also amazing about Einstein is that he came up with the idea of photons not while sitting in a plush office in central europe sipping coffee, but whilst holding down an exhausting job at the Swiss patent office. In the same year, 1905, which later became known as ‘the miracle year’, he had three more ideas, which he turned into 3 scientific papers, all of which were as revolutionary as the first. Genius!
The most important of these three ideas was special relativity. Although many people find Einstein’s science a little daunting, relativity isn’t that hard to understand as a basic principle. The idea is based upon the fact that when something is moving at a constant speed, the laws of motion are the same as when it’s standing still. Imagine bouncing a ball in a cabin on a ferry moving at a constant speed from Dover to Calais. The ship is moving, but the ball will still bounce straight up and down as if the ship was at rest.
That led up Einstein to wonder about the definition of ‘at rest’, since if the ship is in a dock, it’s stationary relative to the earth, but it’s not stationary relative to, say Jupiter, since the whole earth is moving through space anyway. What then do we mean when we say something is ‘at rest?’ Einstein wrote later that he knew immediately after first thinking these thoughts that we can only ever talk about something being at rest relative to something else.
That’s essentially the theory, but it was Einstein’s commitment to carefully exploring the mathematical repercussions of this idea that was his real genius. This where it gets complicated! So I’ve composed a set of amusingly budget videos to try and explain where Einstein’s logic took him.
So the speed of time is absolutely constant, no matter the position of the observer. How can we make sense of that fact? Before Einstein was able to make sense of it, he had to come to the realisation that the concept of relativity applies not only to motion, but vitally, to time as well:
There’s a much better explanatory video here.
So time actually is an incredibly hard thing to understand. When we say that Josh ate a pizza at 2.14am, what we mean is that Josh ate a pizza simultaneously with the hands of our watches pointing to 2.14am (and presumably also with Josh being extremely wasted).
But since we’ve just discovered that simultaneity is relative, we realise that actually there is no such thing as objective time. It’s not an extraneous force which is constant no matter where you are. The upshot of all this postulating is that time becomes rather plastic. Another thought experiment demonstrates what I mean:
Imagine you’re on a train with a mirror on the floor and on the ceiling. Light is bouncing up and down between the two mirrors in a straight line. Now imagine you’re on a platform watching yourself watching the mirrors and the light as the train whizzes past. Now, from your perspective, the light is moving diagonally up and down, since the train is in motion. So it’s moving a longer distance, right?
But since we know the speed of light is always exactly the same, what we can say is that in relative terms, the distance travelled or the time the light is taking must be switching around. We can’t really be sure which though, which gives rise to the idea of space-time; space and time are inextricably linked.
Well, that’s the basis of Einstein’s amazing idea. I hope my explanation made some sense!