Friday, 4 October 2013

Relatively Speaking

Sometimes I think insufficient love is given to Galilean Relativity. Ever since the Special and General Relativities became so fashionable in the early 20th Century, I don't think simple old Galilean Relativity has been getting its due. And I intend to remedy that today.  

Asked by a journalist in 1919 whether it was true that only three people in the world understood Albert Einstein's theory of General Relativity, Mathematician and all-round smug git, Arthur Eddington is reputed to have replied, "Who's the third?" I like to imagine that the next question the journalist asked was: "How did you manage to wangle a two year trip to New Zealand to study an eclipse at a time when all of Europe is engaged in bloody war and can I come with you?" 

To understand General Relativity you need to wrap your skull around ideas such as four-dimensional curved spacetime and the equivalence of gravity and acceleration. Even its predecessor, Special Relativity, requires you to suspend intuition so far as to imagine that the Speed of Light is the same for all observers no matter how fast they are travelling. But Galilean Relativity is so simple and intuitive that I invented it when I was Fourteen.

I mean, I didn't get credited with it or anything. It's not called Finnginnian Relativity because obviously Galileo Galilei got there first in 1632 (at the age of 68!).  

Late developer Galileo Galilei
I had never heard of Galilean Relativity, when, travelling on an escalator on a school trip in the mid-1990s, I felt compelled to remark to my companion: "How do we know we are moving? We might just be staying still and everything else is moving past us." "Finn," my companion replied, "That sort of comment is precisely why you are never going to get off with any girl ever."

I saw immediately that he was right and resolved to keep all my relativistic thoughts firmly on the inside of my head from that moment on. 

Years later, I read about Galilean Relativity and how early modern scientists had realised that the question, "Are we moving?" has no meaning unless a reference frame is specified. "Is everything moving relative to my static position on this escalator?" is equally as valid a question as "Is this escalator moving?"

These days, I'm not so self conscious, I'll just go ahead and talk about Galilean Relativity and if nobody wants to listen... well... that's what this blog is for!

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