The first thing Simon said this morning was: “Mom, do you know that if you keep moving, you get one quadrillionth of a second per second younger than if you just sit still?” Simon had heard this fact on VSauce the night before (and I think we watched another VSauce video earlier and also read in our *Eine kleine Nachtphysik* book about how in spacetime, we barely move through space and only move through time, and the faster one moves through space, the slower one moves through time – that’s why time stops for anyone moving through space at the speed of light.

This morning, Simon wanted to calculate how much less older one gets within a lifetime of 100 years if one keeps moving all the time. He first calculated how many seconds there are in a 100 years. He said he knew that there were 10! seconds in 6 weeks and went on from there:

And then, multiplied that value by one quadrillionth (see below). He ended up with approximately one three hundred thousandth of a second per 100 years – getting that much less older than if you sit still for a century. The value is very approximate, as Simon is not exactly sure whether the initial value of one quadrillionth per second is correct – it could be even less!