About Philip
Philip Liu leads TechCayman’s education programmes, running robotics camps, hackerspaces and in-school workshops that support Cayman’s future tech talent. A Harvard-trained computer scientist, Phil has built enterprise software and high-frequency trading systems. In Phil’s Corner, he shares what’s been on his mind.
One Second Here Is A Year Over There
When I was in university, an acquaintance (a music major) sat down across from me in the dining hall at lunch. He knew I was taking some physics intro courses and asked me if I could explain the theory of special relativity to him, in simple terms. If you’ve ever wondered how it works, when they refer to it in movies that time passes at different rates in different places, here was my attempt.
The base of the dilemma is that time and space may appear to dilate or contract based on different frames of reference. This clearly sounds impossible, so just hear me out.
Imagine there is a train. There is a passenger on the train, as well as an observer outside the train. It’s a long train, with a single light in every window that flashes just as that window passes the observer. As the train passes, the observer sees a series of flashing lights in windows. So far so good?
Now the train starts to speed up. The observer sees the light flashing faster and faster, because the windows are passing faster and faster. Ok, duh. Now the train is going so fast that the flashes start to blur into one another. One flash starting just as the previous ended. Now faster, the lights appear to pulse, as one flash starts before the previous has finished. Soon, the train is going so fast that the flashes just look like one continuous light.
The train keeps going faster.
The observer now sees one continuous light that starts at the head of the train and ends with the caboose, which lasts a certain amount of time – the time it takes for the whole train to pass.
The train goes faster.
The length of time the observer sees the continuous light starts to get shorter and shorter because the time it takes for the train to pass gets shorter.
The train goes even faster, now traveling as fast as theoretically possible, the speed of light.
The observer now just sees a single flash of light and the entire train has passed.
To the observer outside the train, the length of the train has contracted to a single window, and the time it takes to pass is an instant. For the passenger on the train, time is passing normally, and the train is still many cars long. So, depending on your frame of reference, time and space may appear to dilate or contract when velocity approaches the speed of light!
And that train would certainly be handy for my morning commute.
Phil’s Corner is a personal column written by Philip Liu.
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