The advancement of science and technology has enabled us to gradually understand the world we live in, and our outlook on the universe is also changing subtly. Someone raised the question: If you stand 100 light years away from yourself, can you see your past life?
Image source NASA
As we all know, light-year is a unit of distance, which is the distance of light traveling in a straight line in the vacuum of the universe for one year. Some people think that if a star is 22 light-years away from the earth, the star we see when looking up at the starry sky at night is actually 22 years ago. In fact, this statement is correct. For example, the sun we see is about 150 million kilometers away from the earth where we are, and it takes about eight minutes or ten seconds for the light it emits to travel to the earth, so the sun we see is actually what it looked like eight minutes ago. Up.
Theoretically speaking, if we are in the universe, standing light-years from the earth, then the time we see is the distance divided by the light beam, so standing 100 light-years away from ourselves can see What I was like 100 years ago. If we ignore the effect of the expansion of the universe, if the light of a cosmic body that emits light in the universe spreads in the universe, so how many light-years away this celestial body is from us, then we basically see it how many years ago it was. However, the earth is a planet and does not emit light. It is unrealistic for the light generated by human beings to spread in the universe, because the light is too weak. But science and technology have unexpected power. Maybe human beings can travel back to the past through the time machine in the future! Image source of
: NASA
