Top 10 Reasons Why Sex at the Speed of Light is not an Advisable Form Of Procreation 10. Penile length contraction: According to the relativistic theory of length contraction, this is an inevitable consequence of performing sex at the speed of light. An average penis of length 13cm traveling at 99% the speed of light… Continue reading Top 10 Reasons Why Sex at the Speed of Light is not an Advisable Form Of Procreation