Question

Compared to time kept on Earth, there is a physical slowing of time when you travel at _____.
a. everyday low speeds.
b. relativistic speeds.
c. both A and B
d. none of the above

Answer 1

If the distance between you and another person is changing,
(you are in motion relative to each other, and it doesn't matter
how fast), and you both have clocks, then ...

-- you will say that your clock and your heartbeat are running normally
but his his clock and heartbeat are running slow;

-- he will say that his clock and his heartbeat are running normally
but your clock and heartbeat are running slow.

You'll both be correct.