Einstein was a genius, there is not a single person in the world that disputes this claim. He completed his Ph.D. in 1905, and in the same year, he published a number of papers. These were on the photoelectric effect, Brownian Motion, Special Relativity and the paper where he discussed the equivalence between mass and energy. In this post, we’ll be looking at what Einstein thought about as a precursor to Special Relativity.
Einstein made two postulates (the scientific word for propositions) about the laws of physics before considering relativity. The first postulate was that the laws of physics are the same regardless of how you look at it. The second was that light travels at a constant speed regardless of how you are looking at it. These may seem like really stupid and obvious things to say, but let me give you an example.
Let’s say there were two people. One of them was moving on a train, and the other was waving from the platform. Instantly, an uncertainty exists. The uncertainty is ‘who is moving?’. The obvious answer is the person on the train. However, the person on the train may see it as he’s stationary and the platform is moving. What Einstein’s postulates state is that regardless of whether you’re looking at the situation from the train or the platform, the speed of light is the same, and the laws of physics are the same.
These rules act as a precursor for Special Relativity. Einstein used these postulates as rules of sorts when thinking about Special Relativity. The incredible thing about this is that he used thought experiments before even putting pen to paper. In particular, he devised a thought experiment called the light clock.
The light clock consists of two mirrors with a beam of light bouncing between them. However, this can be quite hard to visualise, so instead, we’ll be thinking about two cars, where somebody passes a tennis ball through their window to the car of the other window. There is also a third person, who is watching the cars from the side. If both cars are stationary, what the people in the cars see is the same as what the observer sees. However, if both cars are traveling in the same direction at the same speed, then according to the observer, the ball travels at an angle, whereas the people in the car see it as travelling at right angles to the direction of the motion of the car.
This is actually an incredibly significant distinction. One of Einstein’s postulates was that the speed of light (the tennis ball) is constant regardless of where you’re observing it from. This means that the people in the car and the observer see the tennis ball travelling at the same speed. However, the observer sees the tennis ball travel a further distance as it is travelling at angles to the car. This means that time must travel slower for the people in the car with respect to the observer.
However, the slowing of time (time dilation) isn’t the only thing which is observed. the observer also sees an increase in mass and a decrease in size.
I hope you’ve found this post interesting! If you have, please be sure to stick around for the next one! A new post will be uploaded every Saturday at 10 AM GMT. The next topic will be on Einstein’s Theory of General Relativity.
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