Question

A young-looking woman astronaut has just arrived home from a long trip. She rushes up to an old gray-haired man and in the ensuing conversation refers to him as her son. How might this be possible? Explain your answer.

Answer 1

She can be his mother if once she left her son on Earth while she went for a space trip at a speed close to the speed of light. Travelling at such a high speed is accompanied by time dilation (the time for the stationary observer on the earth flies faster), so, the son gets old at a faster rate that the mother. As she comes home, we notice that she looks younger than her son.