Newton
What I really admire are people who, through their sheer brain power, can change our views of the world. The first example that comes to mind is Newton’s insight that if the universe were infinite, the night sky would not be dark as everywhere there would be tiny pinpricks of starlight. So, we don’t live in a infinite universe. Another one is Einstein’s thought experiment that proves that time is relative. But see below for a description of that. But, now to John Goodricke and the Variable Star. (for Newton and the Maypole see my post here).
Goodricke
Last year in York, near the Minster, I saw the blue sign above. I thought, what on earth are ‘variable stars’? Behind me, I heard two women say something like. ‘Here it is,”variable stars”‘. I turned around and asked them what was a variable star?
‘Donno’ they said, ‘we’ve ‘just doing this escape room walk around York.’ They showed me a booklet they had received on the internet,. This is what I would call a treasure trail. Sadly, they showed no interest in finding out what a variable star is!
Aristotle and ancient philosophers held that the universe was unchanging and eternal. The first breach in that theory was the identification in 1638 of star Omicron Ceti. Johannes Holwarda discovered that the star pulsed on an 11-month cycle. This and the discovery, of supernovae (first observed in 1572), proved that the ‘The starry sky was not eternally invariable’. But there was, as yet, no explanation for the phenomena.
John Goodricke was educated at Thomas Braidwood‘s Academy, school for deaf pupils in Edinburgh, and Warrington Academy. He returned to live with his parents, who rented an apartment at the Treasurer’s Hall. This is near the Minister in York. He used a friend’s personal observatory to look for variable stars. He found two of the first 10, and was the first to propose a solution. This was that two stars orbited each other causing eclipses between them and the observer. Thus creating a variation in the light emitted. To be able to extrapolate from a simple observation, and provide an explanation which necessitates a complete rethink about the nature of the universe seems, to me, to be awesome.
Einstein’s Thought Experiment
Back to Einstein, his thought experiment was something like this:
A train is travelling through a station. There is an observer on the train towards the front, another on the platform as the train goes through. There are two simultaneous lighting strikes at either end of the train. The observer on the platform sees the strikes as simultaneous. Why? Because she is in the middle between the two lighting strikes and light travels at the same speed. The observer on the train who is near the front of the train will see the lighting strike at the front of the train before the light from the strike at the back of the train can reach him. It has further to go.
This means that time is not a constant, it is relative to the observer. And yet, we think of time as a constant, something that remorselessly ticks forward and which we cannot alter. But it isn’t.
For a better explanation, see https://en.m.wikipedia.org/wiki/Relativity_of_simultaneity
First written 2024, revised 2025