You never know whether an Einsteinian is lying or simply does not know what he is talking about:

https://m.youtube.com/watch?v=QnmnLmwBmfE
Brian Greene: "If you're moving relative to somebody else, time for you slows down."

Special relativity, if one sticks to its VALID inferences, predicts the opposite: If you're moving relative to somebody else, time for you SPEEDS UP - you observe the other person's clock running slow:

http://www.people.fas.harvard.edu/~djmorin/chap11.pdf
David Morin, Introduction to Classical Mechanics With Problems and Solutions, Chapter 11, p. 14: "Twin A stays on the earth, while twin B flies quickly to a distant star and back. [...] For the entire outward and return parts of the trip, B does observe A's clock running slow..."

Actually time neither slows down nor speeds up for the moving observer - the predictions of special relativity are absurd consequences of Einstein's 1905 false constant-speed-of-light postulate.

Pentcho Valev