It pays to ride as fast as you can!

Relatively speaking….

…that is.  Einsteinian Relativity is one of those mind bending things to get your head around.  There’s that stupid drunken pub debate about what would happen if you were watching a car drive past at 90% of the speed of light and then the driver turned the lights on, etc etc.  Would the light from the headlights end up doing 190% of the speed of light? Nope, it would travel at the speed of light!  The speed of light is constant, no matter how fast you are going.

  The basic equation for speed is Speed=Distance/Time.  In our theoretical car therefore, if the Distance from the bonnet and the Distance from the headlights is the same, and the Speed of light is the same, the only way the two equations can be balanced is by altering the Time variable.

  This is a fab effect known as Time Dilation and affects any object travelling at any speed. The greater the speed, the greater the time dilation. It’s not just theoretical – GPS satellites which travel at high speeds have to compensate for onboard time running microscopically slower than time on Earth. I think I read somewhere that without this compensation they’d get 4 feet further out of position every day.

  Anyway, what got me thinking was the fact that the Apollo astronauts actually travelled about 70 milliseconds through time as a result of their long, fast trip to the moon. (In fact, Jim Lovell and John Young went twice – that’s a whopping 140 milliseconds younger!!)

 * (See ‘The Twin Paradox’ at the bottom of the page)

  I got bored and decided to work out the amount of time dilation I’d experienced in my PB 25 mile TT of 53mins 50 secs!

  The formula is fairly straightforward:

  If you bang the numbers in, you get a ‘Relativistic Factor’ of 9x10^-17

 So, over 53mins 50secs which is 3230 seconds, that gives a time dilation of 2.907x10^12 seconds! That’s 0.000000000002907 seconds difference (2.907 picoseconds or 2.907 trillionths of a second) between the time I experienced on the bike compared with the timekeepers time!

 There’s an associated relativistic phenomenon called ‘Lorentz Transformation’ whereby the length of an object appears shortened at relativistic speeds. Using the same Relativistic Factor, at 27.7mph the bike from the point of the view of the timekeeper on the finish line looks 1.395x10^-13m shorter than it actually is. That’s 0.1395 picometres or 0.1395 trillions of a metre

 Obviously, the effects on time and length (and even mass) are tiny at these low speeds but at speeds much closer to the speed of light, they are huge (that’s why people on the pavement don’t look skinny when you zip past them on your bike!).

At 99.999999999999% of the speed of light, a 12 hour time trial from the rider’s point of view would be the equivalent of 10,000 years for the time keepers!

My head is completely done in…..

Think I need to get out more…….


* There are two twin brothers. On their thirtieth birthday, one of the brothers goes on a space journey in a superfast rocket that travels at 99% of the speed of light. The space traveller stays on his journey for precisely one year, whereupon he returns to Earth on his 31st birthday. On Earth, however, seven years have elapsed, so his twin brother is 37 years old at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveller’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers, i.e. both still need five minutes to shave each morning in their respective reference frame.