Seeing into the past?

With these space based telescopes they are claiming to see back billions of years ago, as in currently viewing how things were then not how they are presently. 
If there existed the same technology on the other end wouldn't they be able to see our past as well? It makes me think if they had advanced telescopes and gps coordinates they could see things that occured on earth that we may have missed. 

Anonymous2020-12-07T20:54:38Z

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If they were 10,000 light years away and looking at the Earth right now, they would see things on Earth as they were 10,000 years ago.  And they could see things we might have missed but that wouldn't help because even if they sent a message it would take 10,000 years to get here.

Anonymous2020-12-08T13:34:39Z

 That is assuming any intelligent life exists in Space zxj
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jeffdanielk2020-12-08T04:24:39Z

Yes, aliens looking at earth would see it as it was in the past because light takes time to get to them. But no telescope could be powerful enough to see details on earth from light years away. But maybe aliens 75 light years away with a gigantic telescope are right now seeing the atomic explosion of the bomb the US dropped on Japan 75 years ago. 

quantumclaustrophobe2020-12-07T22:23:27Z

That's true... We see the sun as it was 8 1/3 minutes ago - but, if someone was standing on the sun (and somehow not being turned into plasma), they'd see the Earth as it was 8 1/3 minutes ago.  
We see the Andromeda galaxy as it was 2.2 million years ago - and, the folks in Andromeda (if there are any) are seeing the Milky Way as we were 2.2 million years in our past. 

If you were to wave at someone in Andromeda right now, they wouldn't *see* that wave for another 2.2 million years - which means, if they managed to wave back, we wouldn't see their answer for 4.4 million years after our initial wave...  

If someone in a galaxy 65 million light years away had a telescope that could resolve Earth from such a distance, they could see the asteroid hitting our planet that will be wiping out the dinosaurs. 

Stan Dalone2020-12-07T20:54:07Z

Yes, telescopes observing distant places see them as they were when the light left them.  So when we look at the Andromeda Galaxy we're actually seeing it as it was 2.5 million years ago, because it's 2.5 million light-years away.

However, there's no way to see any detail on a planet in Andromeda.  The level of difficulty you can see with a telescope is dependent on how big your collecting surface (lens or mirror) is vs. how far away - so it's a question of physics rather than technology.  You couldn't build a more "advanced" telescope that could see more detail than what we can do today.

The fact is that, because of the physics limitation, it's impossible to see something as small as a person, or a lunar lander, on the surface of the Moon from here.  I don't know the mathematics of this exactly, but in order to see something that small that far away, your collecting surface would have to be something like planet-size.  And that's only a quarter million miles away (about 1.5 light-*seconds*).

Edit: I think Carol Okla was a victim of Autocorrect there.  The episode she's referring to is "The Squire of Gothos".

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