I couldn't find an answer online, maybe someone here will know.
If a person left Earth, flew the speed of light in one direction for 6 months, made a u-turn then travels 6 months back at the speed of light. When they got back to Earth, how many years would have passed on Earth?
If there a math formula for this?
One year is correct because the time to measure how long the person traveled would be relative to the time the person started. What would be difficult to conceptualize would be how much distance was actually covered.