Question

A space traveler is moving at a speed of 0.6 times the speed of light as seen from the Earth's frame of reference. After one year passes on Earth, the space traveler will

• A. age more than one year
• B. age less than one year
• C. age exactly one year
• D. not age at all
• E. become younger

Answer 1

The correct option is B age less than one year

Given : $v=0.6c$

The time elapsed on earth $t=1$ year.

Using relativity, time elapsed in the space traveler frame $\tau =t\sqrt{1-{\beta }^2}$ where $\beta =v/c=0.6$

$\therefore$ $\tau =1\times \sqrt{1-(0.6{)}^2}=1\times 0.8=0.8$ year $⟹$ $\tau <t$

Thus times elapsed in space traveler frame is less than that of earth, so space traveler will age less than one year.