*Steve Colby asked the Naked Scientists:* I have recently discovered the

Naked Scientists podcasts and am enjoying them immensely. I have a couple of questions for you.

Question 1: Is it true that we get faster as we get older?

Consider that, in the Special Theory of Relativity, as objects move faster, their length decreases in proportion to the Lorentz Factor. Also, the relativistic mass of a moving object is increased over the rest mass by the same factor. Now I have observed that, as I get older, I am getting shorter and heavier. I conclude therefore that I must be getting faster.

Now for a legitimate question: Given the invariant speed of light and the Lorentz length contraction, would a reader who has 20-20 vision at rest need reading glasses when riding the TGV at relativistic speeds, due to Lorentz contraction of the eyeball?

I look forward to hearing your answer on a

future podcast (during a slow science week, no doubt)

Best Regards,

R. Steve Colby, PhD

Raleigh, North Carolina, USA

*What do you think?*