if you can look back at the universe billions of years ago, why can't we see the Earth a billion or so years a

Question

We're discussing why one couldn't see earth back in time if you can see near the beginning of the universe. why couldn't you point the telescope to look at earth a million or billion or whatever...

Answer 1

Because the reason you can look at the universe from a billion years ago is because the light is that old. To see Earth from a billion years ago, a telescope would have to be placed 1 billion light years from earth.

Answer 2

To see Earth as it was a billion years ago, we would have to look at it from a place a billion light years away. There are two obvious problems with that. One, how do we get to a place a billion light years away when we can't even send an unmanned space craft to the nearest star only 4 light years away? And two, there is no possible telescope that can see something as small as the Earth from such a distance. The smallest thing we can see from so far away is an entire galaxy, even with the biggest and best telescopes. Even with the Hubble Space Telescope.

Answer 3

The folks have it all wrong. You don't have to be a billion light years away, you only have to set up conditions for the light to travel a billion light years. Set up a few billion mirrors on a geosynchronous satellite and another few billion on earth, pointed precisely, and the light will bounce back and forth for a few million years. Stand in front of the last mirror, and people who are alive millions of years from now will be able to see you.

Of course, there is the underlying problem that the light that left earth yesterday (let alone a billion years ago) is already a light-day away. You'll never catch up with it. You can only set things up to see today from sometime in the future.

I'd probably stick with a webcam.

Answer 4

You can. You just need great big lenses and be a billion light years away. The tricky thing, as I understand it, is that as you travel out to this distant location in your rocket telescope, and assuming you want a really fast rocket, as you approach the speed of light, time slows to a crawl, relative to earth time, so that when you look back, you will be so far in the future that the past you see won't seem very past like at all. I think.

Answer 5

there is a way....

you would have to view the billion year old light.

While most people think this means you would have to be billions of light years away, it isn't necessarily a requirement.

Light doesn't always travel in a straight line. It is bent as it travels by various objects. IF light is bent enough and in the right way, it could be bent upon itself in a circle.

This would enable us to view the earth in the past because we would view the light that set out into the universe and somehow found its way back here.

Another way is via a wormhole. A fold in time-space could catch us up to where the old-light is... and provide a viewing window. Ok ok... so I just saw the movie Deja Vu. (cool!)

Answer 6

the only reason you can see things in the past is because the objects you see are billions of light years away from you. it takes the light given off by these objects billions of years to reach earth. if earth were a billion light years away from where you were, and you found earth with your telescope, you would then see earth as it appeared a billion years ago. however there is no way for us to get something a billion light years away from earth because to do so (without taking an ungodly ammount of time) would require us to travel faster than the speed of light which, according to einstein, is impossible.

Answer 7

Because light reflected from the earth moves away from the earth. In order to see the earth as it was a million years ago, you would have to be sitting somewhere in the universe a million light years away from the earth.

Answer 8

You need a place to stand in to look at earth. You could look at any object billions of years back, provided that object is billions of light years away from you. So, to see earth billions of years back, you need to be billions of light years away from it.

Answer 9

When you look at a distant object in the sky, you are seeing it as it was many years ago. This is not quite the same as looking back in time to any event or object you wish. The object has to be located at a great enough distance so that the light takes a long time to get here. The object also has to emit enough light to be seen at that distance.

Answer 10

You are standing on earth,so you can not look back at yourself.
If you could stand on the sun you could look back at the earth and see it as it existed eight minutes ago!