Seeing the dinosaurs...

[EGarrett]

Been thinking about this...and I see no reason for it to be impossible.

We see the night sky as it looked millions of years ago, so objects in the night sky see the earth as it looked millions of years ago.

So theoretically...if you could travel 65 million light-years away from earth in a black hole...then look back with a really powerful telescope, couldn't you see the dinosaurs and other prehistoric creatures walking around?

Likewise...you could probably see the Renaissance from 500 light years away? World War II from 60 light years?

Now...let's say we're trying to see some event from 60 years ago. If that light were reflected off an object at the right angle 30 light years away, we could pick it up with a telescope here on earth and have a constant view of things that were happening on earth 60 years ago to the day?

Thoughts? Flaws?

 

[The Don]

In theory yes ish....

In practice so few photons would be able to make the return journey back to Earth - inverse square law and all that (the rest would travel in different directions) - that you wouldn't be able to "see" anything coherent.

Photons are also not tagged so you wouldn't be able to say which were part of the earth reflection and which cane from somehting else. You can see stars because they produce a sh!t load of photons.

Also if there was relative motion between the Earth and the mirror, the light would be "shifted" in the same way that sound is shifted by the Doppler effect.

 

[Brian the Snail]

Now...let's say we're trying to see some event from 60 years ago. If that light were reflected off an object at the right angle 30 light years away, we could pick it up with a telescope here on earth and have a constant view of things that were happening on earth 60 years ago to the day?

I don't think that there's a problem with this in principle. But of course in practice it's pretty much impossible. For one thing, although you'll be seeing things from 60 years in the past, they'll look like they're at a distance of 60 light years away. So to see soldiers storming the beaches of Normandy on D-Day you're going to need one hell of a telescope!

Plus there's a problem with putting a sufficiently large mirror 30 light years away, which will have to be aligned (and remain aligned) to an extremely high precision, and be big enough to be able to collect enough light to see with your super-dooper telescope.

 

[blackjackal]

The only flaw that I see is that the light from earth would be so faint even at 1 light year that it would be difficult to view anything specific.

 

[EGarrett]

Hmmm...

Well...for starters, we could theoretically place an extremely large mirror on Mars (a project which would probably take a year or two) and with a telescope, be able to see, what, 8-10 minutes into the past?

That might actually be useful.

 

[The Don]

Or instead you could just place a camera on Mars of course you'd only be seeing the bits of the Earth facing Mars.

Altenatively you could ring the Earth with a series of Satellites which film everything going on and feed this information into a vast information bank from which you can retrieve the information as required.


Or is this already happening ?? Bwahahahahahah!!!!!!

 

[drkitten]

Hmmm...

Well...for starters, we could theoretically place an extremely large mirror on Mars (a project which would probably take a year or two) and with a telescope, be able to see, what, 8-10 minutes into the past?

That might actually be useful.

At what were you planning on looking?

I can get the same effect much more cheaply with a video camera and a short tape loop. It has the advantage that whatever I want to look at will be large enough to see.

 

[The Don]

Look, if you want to see dinosaurs, I can probably hook you up with someone who can provide something *ahem* pharmacological to enable you to do it

 

[Brian the Snail]

Or become a young earth creationist. Then you'll think that Jurassic Park is a documentary.

Problem solved!