What if you could get light-years away from Earth...

ßleck

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What if you could get light-years away from Earth and had some sort of super-telescope that was advanced enough to view the Earth, wouldn't it be possible to witness the past?

I mean since you can't actually see an object until the light coming from it reaches your eyes, why wouldn't the same thing happen far away in space with the "object" being the Earth. You can't see a star until its light reaches Earth which can take years, so we are technically already looking at their past.

I understand that technically you are already seeing the past, but that must be only a few micro-seconds in the past. What I'm talking about is looking years back, like being able to see the birth of your grandparents.

Couldn't all this also mean that if we could travel faster than the speed of light that we could travel back in time?

Also think of the possibilities! We just "believe" in the content of old books and paintings to understand our history, yet we can never be sure about what actually happened. There are countless mysteries of the past that remain unsolved. There are also many conflicts going on because people disagree about what actually happened in the past. So many problems would be solved. You could also just watch yourself being born and stuff like that is just awesome to see.

I've had this thought for ages and never did any effort to find an answer... Until today I guess. I'm sure some of you thought about this too. Anyway, enough from me. I want to hear what you guys think!
 

Veho

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You should read The Light of Other Days, it's a novel by A.C. Clarke and Stephen Baxter that talks about the effect such a technology (wormholes + telescope = seeing into the past) would have on our society and the world. There's some interesting stuff.
 

FAST6191

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We could debate physics (and it is late enough with being hopped up on sugar enough to go in for it) though Veho pretty much stopped that for a while. Likewise "if we could travel[/communicate] faster than the speed of light" holds so many more interesting possibilities/options/thought experiments than watching my birth (I came out screaming and covered in gunk, not much changed for about two decades and even then the change was of suspect merit) or even much of history for me (screw the past -- they did not even have antibiotics).

I do have to say though "We just "believe" in the content of old books and paintings to understand our history" does rather undermine basically the entire study of history where "determine the quality of your sources" is as important as "hypothesis, test, repeat" is to general science. Likewise this magic telescope had better be pretty magic to hear things, smell things, interpret brainwaves, consider the ramifications of information travel (how many times have battles been fought after the end of wars because nobody has yet manged to say "it is off lads"?).
 

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If I could get light years away from earth, I'd hide my porn there.
 
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Gahars

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Couldn't all this also mean that if we could travel faster than the speed of light that we could travel back in time?

Actually, you would be travelling into the future (What ya know 'bout my time dilation?) and just receiving images from the past in your present.

...Maybe we should stop before somebody gets an aneurysm.
 
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FAST6191

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If I could get light years away from earth, I'd hide my porn there.
But everybody views porn and nobody that matters (assuming you are in one of the nicer countries in the world) cares. That seems like an awful lot of effort for no real gains.

I'd find the aliens and betray humanity for the good of humanity
General logic has it that any aliens that pull off faster than light travel are so advanced and evolutionarily speaking likely to just eat you that it does not matter, likewise if you are the travelling alien what are the inferior life forms going to do about humanity? Also does humanity matter at this point?
 

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The short answer is yes, you could if the light of the Earth could be seen from other planets and you could make out the details on the surface. In reality, you wouldn't be able to make out any details from so far away. The light bouncing off the Earth is too dim. That's why we detect extrasolar planets by means other than seeing them (e.g. their effect on their suns, etc).
 

Black-Ice

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General logic has it that any aliens that pull off faster than light travel are so advanced and evolutionarily speaking likely to just eat you that it does not matter, likewise if you are the travelling alien what are the inferior life forms going to do about humanity? Also does humanity matter at this point?

........D:
 
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Lacius

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Couldn't all this also mean that if we could travel faster than the speed of light that we could travel back in time?

Also, no, it's impossible to travel faster than light and go back in time that way. The only way to cheat the speed of light and travel faster involves hypothetical ways of manipulating spacetime (e.g. wormholes, Alcubierre drive, etc). Alcubierre drive, for example, wouldn't result in backwards time travel since the ship being used technically won't be moving; the bubble with space expanded behind it and contracted in front of it would be the thing moving and everything in the bubble would be stationary. Backwards time travel could be possible via other means.

The reason people say faster-than-light travel would result in backwards time travel is because time slows down for a person the closer to the speed of light he/she gets. This is time dilation and is a part of Einstein's theory of relativity. This happens because nothing can travel faster than light. Imagine I'm on a train traveling at 99.9% the speed of light. If I'm on that train and try to run forward, one would think my running speed and the speed of the train would be added together for my actual speed, but because I can't exceed the speed of light, time literally slows down for me and my combined speeds will never exceed the speed of light.

As Gahars already alluded to, time dilation could result in effective time travel to the future. If I stay on a spaceship, train, etc. traveling at close to the speed of light long enough, I will get off the craft and only feel like a fraction of the time has passed.
 

ßleck

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You should read The Light of Other Days, it's a novel by A.C. Clarke and Stephen Baxter that talks about the effect such a technology (wormholes + telescope = seeing into the past) would have on our society and the world. There's some interesting stuff.

Seems interesting. Might just give that a read.
We could debate physics (and it is late enough with being hopped up on sugar enough to go in for it) though Veho pretty much stopped that for a while. Likewise "if we could travel[/communicate] faster than the speed of light" holds so many more interesting possibilities/options/thought experiments than watching my birth (I came out screaming and covered in gunk, not much changed for about two decades and even then the change was of suspect merit) or even much of history for me (screw the past -- they did not even have antibiotics).

I do have to say though "We just "believe" in the content of old books and paintings to understand our history" does rather undermine basically the entire study of history where "determine the quality of your sources" is as important as "hypothesis, test, repeat" is to general science. Likewise this magic telescope had better be pretty magic to hear things, smell things, interpret brainwaves, consider the ramifications of information travel (how many times have battles been fought after the end of wars because nobody has yet manged to say "it is off lads"?).
Maybe we SHOULD debate physics. If you make a statement I would like to know exactly what you base your thoughts on and on a topic like this physics seems inevitable. Anyway I agree about how my example about watching your birth might have been a sligthly more simple and boring example.

That's the problem about the study of history. You have to rely on sources. Sadly the only way to know for sure what happened in the past is to have actually seen the event that happened in the past. I'm pretty sure more than half of what we know about the past is wrong. That's because there has to be some kind of document containing the details of what happened at a specific event and the person who made the document must be really neutral about the event. The further you go back the less sources there are and you can't always fully trust someone.
I'd find the aliens and betray humanity for the good of humanity
If we find intelligent aliens we should exchange pictures of our pasts. :yay:
Actually, you would be travelling into the future (What ya know 'bout my time dilation?) and just receiving images from the past in your present.

...Maybe we should stop before somebody gets an aneurysm.

So... We would just "see" the past? Also, we should go on. Anyone who dies, dies for SCIENCE!
The short answer is yes, you could if the light of the Earth could be seen from other planets and you could make out the details on the surface. In reality, you wouldn't be able to make out any details from so far away. The light bouncing off the Earth is too dim. That's why we detect extrasolar planets by means other than seeing them (e.g. their effect on their suns, etc).

Well I said IF we had some kind of super-telescope :D
Also, no, it's impossible to travel faster than light and go back in time that way.
My question was IF we could travel faster than light, could we travel back in time? Not if it is possible to go faster than the speed of light. But I see how it might not be possible and because of that backwards time travel isn't possible at all in that manner.
 

Foxi4

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Also, no, it's impossible to travel faster than light and go back in time that way.

I don't think he meant time travel in that sense - what he referred to was if we could witness events from the past if we were to travel faster than light which, in theory, is possible.

Our eyes detect light reflecting off surfaces - this is what we see, meaning, witness. If we were to travel faster than these reflected beams, "overtake" them so-to-speak and then face the direction they came from then for all intents and purposes, we should be able to see light that was reflected a long time ago (unless they were reflected once more on the way to us or otherwise distorted, of course).

Naturally we'd have to assume that our ship would be weightless and caused no resistance whatsoever to even have a slim chance at beating the speed of light if we were to use the "conventional" sense of the word "travel" unless, as you said earlier, we'd find a way to fold space, effectively decreasing the distance between Point A and Point B to zero.
 

Lacius

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My question was IF we could travel faster than light, could we travel back in time? Not if it is possible to go faster than the speed of light. But I see how it might not be possible and because of that backwards time travel isn't possible at all in that manner.
It is impossible to travel backwards through time due to the effects of time dilation. Faster-than-light travel might be possible if one cheats, but it's purely speculative and wouldn't have anything to do with time dilation. There might also be other ways to travel backwards in time that don't have to do with faster-than-light travel, but those are also speculative.

I don't think he meant time travel in that sense - what he referred to was if we could witness events from the past if we were to travel faster than light which, in theory, is possible.

It was the latter and then the former; both ideas were mentioned in the original post. I got it. The idea that we could literally travel backwards in time if we somehow traveled faster than light is a common misconception about the theory of relativity that I was correcting.
 
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Foxi4

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It was the latter and then the former; both ideas were mentioned in the original post. I got it. The idea that we could literally travel backwards in time if we somehow traveled faster than light is a common misconception about the theory of relativity that I was correcting.

Fair enough. :)
 

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