Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Could we be made from a star we see in the night sky?

Learn more physics!

Most recent answer: 08/12/2013
Q:
As far as I am aware, all substances (e.g.oxygen, iron, gold etc) come from the nuclear fusion of stars, as well as the destruction of the star. As well as that, when we look into the night sky, we see, for example, proxima centauri as it was 5 years ago. Does that mean, when we look at a star at the far reaches of the galaxy, that star might have exploded billions of years ago and that perhaps the materials that we are made of (carbon for example)came from that star? Technically we would be looking into our own past!
- Danny (age 18)
England
A:

Hi Danny,

That's a cool idea, but it wouldn't work as you've imagined it. If we were created from the elements forged in a star we see in the night sky, then those elements would have to have traveled faster than the speed of light to reach the earth, form us, and then wait for the light from the star to arrive.

So, we can't see our past by this method. It's possible that some of the earth was forged in a star which is still alive today, but we when we look at the sky, we will necessarily see the star long after it created the atoms which made it to what we now call earth.

David Schmid


(published on 08/12/2013)

Follow-up on this answer.