[Q_is_4_Quantum]

Not OP, and I don't have time (hah) to do the calculation but a rough rule of thumb is that if you take a "normal size" of a quantity (mass, speed, etc) then relativistic effects become measurable when you scale it by c^2, ie about 10^17. So e.g. We have had clocks for a while that are accurate to a part in 10^18, so they can measure time dilation at walking speed. Or detect gravitational time dilation when you lift something (the clock!) up one meter in the earths gravitational field.

Yet another way of saying how amazing this new result is: A second is much "closer" to the age of the universe than it is to a zeptosecond.

[caf]

It is worth stating this explicitly - NIST has in fact done the practical experiments to demonstrate time dilation at both 10ms⁻¹ relative velocity and 1m relative height in Earth's gravitational well:

https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=90505...

[SiVal]

I'm going to guess that the comment about measuring the weight of a person was not referring to measuring his walking speed nor his height. It's more likely referring to his personal gravity well and the time dilation it causes as he approaches and you go further into it. Still a guess, though.