Hey everyone! This is a completely off of the wall concept that I was wondering about.

If we are ever able to build an amazing enough telescope (far better than what we have - the kind needed to see freckles on planets thousands of light years away), and we are able to find a reflective surface in deep space at the right angle, would it be possible to observe our own reflection and see ancient earth unfold in real time? Watch dinosaurs live out their lives?

In a general sense, I guess I'm really just asking if you guys think we will ever be able to take advantage of the speed of light in some way to observe our ancient past. If its as simple as having another perspective in space, it seems like technology could get us there rather easy.

That would be an amazing thing, but I'm not sure how well it would work. Light scatters and diffuses a lot over distances, so anything you would find would be fuzzy and blurry at best.

However, this is a GREAT idea for something in a game! Imagine that the point of the game is to determine the location of some secret item and the only way to find it is by watching the past unfold. Could definitely be a great element!

These types of ideas frequently keep me up at night :)

In theory, yeah. In practice, the telescope and mirror would both have to be immensely large, precise and flat... From a sci-fi point of view, you'd probably invent some kind of synthetic aperture telescope (e.g. a swarm of millions of probes, constantly moving through our solar system at high speeds, acting as one device) to get around the size issue, and discover some kind of gravitational lens effect that is somehow acting like a giant chrome ball

A telescope magnifies existing light ... it does not some how "gather" light from different time periods .

It definitely would make for an awesome idea for a game! It made for quite the spectacular piece in the 2006 movie Deja Vu. The film isn't all that great, IMO, but the space age tech featured in the film is very much similar in concept to viewing events in the past. It is worth a watch just to catch the sci-fi tech in action. It is definitely cool stuff.

A telescope magnifies existing light ... it does not some how "gather" light from different time periods .

The idea is that the light you see would have been emitted several million/billion years ago. When you look up at the moon, you're not really seeing "the moon", you're seeing it as it was a little more than a second ago. When you look at distant galaxies with a powerful telescope, you are really seeing galaxies that existed billions of years ago, and probably don't look the same or even exist anymore today.

One problem with this idea is that our view of the old earth is going to be played back at normal speed. So if you're unlucky you could be a million years too early to see dinosaurs or the first humans or whatnot, and there's nothing you could do about it!

One problem with this idea is that our view of the old earth is going to be played back at normal speed. So if you're unlucky you could be a million years too early to see dinosaurs or the first humans or whatnot, and there's nothing you could do about it!

Yep. Another problem would probably be alignment. I'm not sure how long the show could last if our perspective and the reflective surface are both moving around at different speeds in their respective solar systems and galaxies.

I've also thought of this idea, but in diffrent terms, if we could ever achieve some form of FTL travel, then it'd be possible to set a satillite 65 million light years away, and do the same thing.

The problem thoigh with this is that the earth is constantly moving through space so w/e reflective lense you find would have to of been looking at the earth at just such a time period, and now we would have to be back in a similar position to receive the returned light, it's astronomically unlikely such things would align in such a way. Now then if we placed a satellite with an super amazing lense say 1 light days distance from us we could constantly see everything that happened yesterday. But we'd still need some absoultely amazing tech to be able to see anything of value besides maybe some cloud patterns around the earth.

If we are ever able to build an amazing enough telescope (far better than what we have - the kind needed to see freckles on planets thousands of light years away), and we are able to find a reflective surface in deep space at the right angle, would it be possible to observe our own reflection and see ancient earth unfold in real time? Watch dinosaurs live out their lives?

In a general sense, I guess I'm really just asking if you guys think we will ever be able to take advantage of the speed of light in some way to observe our ancient past. If its as simple as having another perspective in space, it seems like technology could get us there rather easy.

You have two questions.

Is it possible to see things in the past? Yes. Light takes time to travel, so if you found a reflector at a distance you could see things in the past.

Is it possible to watch OUR ancient past? No. At that kind of distance the angular diameter distance would make that practically impossible. The farther away something is, the smaller the angle it takes up. Look at how much light we get from nearby stars and how tiny their angle is. The smaller the angle the less photons there are. You'd be looking at an angle that is hundreds of light years away, or for the dinosaurs, millions of light years away. With our current technology we are able to detect planets at the 50 light year range, and even then they are detected not usually by direct observation of the planets but as statistical analysis of the tiniest blips of signals around a star.

So the planets around Tau Ceti, the are 10 light years away. Even so, we cannot actually see the planets. We can see the tiny variations in the star's light and use that to estimate the properties of the planet itself. There is not enough detectable light coming from the planets to even figure out what kind of atmosphere they have, let alone what was happening on the planet's surface 10 years ago.

Even if you did set up a reflector at the right distance and angle to see back hundreds of years, or thousands of years, or especially millions of years, there won't be enough concentration of light for any meaningful observation.

This is one of those obnoxious moments where math and science diverge. Does the math work? Yes. Are you going to find something out there naturally occurring in the universe that will have the size/position/precision that you'd need for this to actually work? Exceedingly improbable.