I saw the prog in question...
Quote:
Originally Posted by Doggle Avaddit  Do you mean you were watching the television program "Horizon" and they said that one of the stars in our sky could be our own (but younger) Sun? |
Yep that's it.
They said that if the Universe is a 4-dimensional 'doughnut' shape, then looking out into space, your line of sight would eventually double back, and you could maybe see our solar system from behind yourself..... and at such a distance, that you are seeing it as it was billions of years ago.
A few problems with that line of thought though...
First of all - we don't yet know exactly how many spatial dimensions the Universe consists of (Likely to be either the 3 we recognise - or many more - unlikely to be 4) - and we also don't know whether it is doughnut shaped or not....
IF - and that's a mighty
BIG 'IF' - both of those factors co-operate with the theory...
Then other problems come in to play.....
EVERY star you can see in the sky, is inside our galaxy (which is
'only' 100-odd thousand light-years across) - it's impossible to pick out individual stars in other galaxies - well, observatory-class telescopes can to some extent, but only in the very nearest of (relatively) local galaxies.
To see 4 or 5 billion years into the past (when our Sun was young), you would have to look at galaxies 4 or 5 billion light-years away, which can only be seen as a fuzzy blob, in even the biggest telescopes.
The 'Hubble' telescope can see this far (the Ultra-deep field photo goes back almost to the Big-Bang) but positive identification at those distances is impossible. Even if the theory was correct (which is highly unlikely)