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interesting question


aure33
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Hey guys this is my first post here and I registered here just to ask one question because i was thinking about something very cool latley and was wondering if thats true and just wanted someone to tell me if that makes any sence so I thought that here it would be the best place to do since you are all interested in astronomy.

So I was thinking if people could somehow travel very far away from earth lets say 500 light years and then have some means to observe earth from such distance would he be seeing things that happened on earth 500 years ago?

So sorry if my question sounds stupid or something because im not very much into astronomy but im very curious about this particular question :)

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In theory yes - in practice no, the Earth itself would be undetectable from any appreciable distance, let alone detail on the Earth. There's so much gas/dust between the stars that the minute amount of light reflected from the Earth would all be absorbed or scattered. From 500ly even the Sun would be very hard to see.

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the sun would be ~mag 9 or 10 i think not worked it out properly, but sertainly not too faint to see. you would be able to watch things happening to the suns spectrum 500 yrs ago if you were 500lys away :)

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In theory yes - in practice no, the Earth itself would be undetectable from any appreciable distance,

However, if we had the technology to travel 500LY within any conceivable time just to turn around and look back, then we'd likely be able to develop the technology to detect and observe the earth from that distance.

-eli

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However, if we had the technology to travel 500LY within any conceivable time just to turn around and look back, then we'd likely be able to develop the technology to detect and observe the earth from that distance.

No, my point is that the amount of light from the Earth tends to zero at that distance - i.e. there's nothing getting there to detect.

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but obviously it would take at least 500 years (and probably even a bit more) to travel 500 light years away so you could never see earth as it was before you left.

and even abit more? are you talking about hubbles law or something else? cause at that distance the only thing to measure it well would be the time it takes light to get there so 500ly

as for hubbles law that would not apply inside our own galaxy, you would have to go out past M13 and the othe globular clusters to see that effect

ally

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thanks for your answers guys im so excited about this idea of looking back even though its as Ben said practically impossible, i think as for first time it would be amazing enough to be able to observe things that happened on earth few weeks ago which may not be so interesting but still quite amazing :)

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:) yes getting through the oort cloud might not be straight forward, but i hear that physicists in america have successfully teleported information from one ion to another by photons over a meter appart in seperate vacuum tanks. the succes rate was 90% and it represents the first truely successful teleportation ever and in theory they are not limited by any distance so they could teleport information over any distance at the speed of light
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Of course, travelling at the speed of light raises loads of issues about the relativity of time, all sorts of issues I have never really understood entirely.

However, you CAN see "into the past" already. Every time you look at ANYTHING, you are seeing it "in the past". If you look at something even ten meters away, you are actually seeing how it was a fraction of a second ago. If you look at the sun, you are seeing it something like 8 minutes ago. If you look at stars, you really ARE "looking into the past".

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Why are we so hung up on the speed of light ? ok, radio waves travel at the same speed, BUT just because radio is our best means of communication at the moment doesn't mean it will always be so.

We are limited (of course) by the knowledge we have at this moment in time.

For instance, and I know this is far fetched, in a Sci fi book I read when I was a kid, communications officers on deep space ships were always telepaths, because telepathic communication was instantaneous over any distance.

Like I say, far fetched, but in the future, who knows ?

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That's why I never get a clean shave!

:mad:

So if you had a scope with a mirror 5 miles across up in space could you see detail on planets light years away? I always wondered since an evil race in a SciFi book I read 50 years back did this before going out to conquer the galaxy in their mile long battleships that could accelerate at 5c.

:)

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so if we found a worm hole that folds space and got 500 light years away from earth within minutes, then we had a device that could see earth as good as a satalite orbiting earth. then we could see our great great great great great great great grand parents house? and maybe them farming or looking up at the stars thinking whats is our place here on earth?? man this guy who opened the thread has started a whole new world of thiinking for me!!!

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yeah i guess it is kinda bother but i think thats the same what most people from 15th century would have said about traveling to moon just to take few rock samples. Something that sounds totally crazy at the moment might be no surprise in few hundred years if not earlier.

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It might be easier to pop down the local archives and see if you can find any old photos, painting, or whatnot. Travelling 500ly away sounds like a lot of bother just to see the past, if you ask me.

really?? thats like saying look at nasa's websites for pictures of the night sky objects.. you goto get your scope out and look yourself right? its about seeing it yourself while it is happening, i no the light takes time to get here but still it is happening, we are seeing it. I would love to look back at the earth

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