Is it possible to look back in time?

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12sec. Civic

12sec. Civic

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I got a strange idea from the thread: "Question".


Ok, this is all very theoretical, but it is kind of interesting.

I am not sure how far telescopes from earth can see. But I know they can see very far. Because most stars are over 1,000 light years away. In fact, the milky way galaxy is 100,000 light years wide.


Anyways. Here is my way to look back in time. Considering we can see things with telescopes that are millions of light years away, it seems that something 10 light years away would be VERY visible. So, lets say you put a HUGE mirror. I mean a mirror that was as big as texas or alaska (theoretically speaking). So, what if you put this mirror 10 light years away. Also, ignoring the fact that it would take a VERY long time for us to place this mirror 10 light years away.


If the mirror is 10 light years away, the light from it that reaches us has taken 10 years to get from earth to the mirror, and 10 years to get back. So, if you looked towards that light with a high powered telescope you'd see the world 20 years ago. I am quite positive that we have telescoped that can see MUCH further than this in great detail.

Now all we have to do is get a mirror out in space.

Even if we could only get a mirror 1/2 a light year away. We could still look back in time 1 year and see much more detail.

What do you think?
 
Yeah, but you wouldnt really be able to see all tha tgood of detail. You would just see the planet as if it was a rather big star.
 
Well......
that is true..
but the mirror wouldn't reflect OUR image, way too far away
what it would do is reflect the image of stars around it
 
When we look at the nearest star, Proxima Centauri, what we see is 4 years old. Same with the sun, but its only 8 minutes old. So that could be called "looking back in time"

Just to be on the bright side, if for some unknown reason the Sun went supernova, with no explantion. we wouldnt know for 8 minutes.
 
We have a mirror in space, though someone shortened it to Mir... silly people. ;)

You would only be able to see the planet as a whole, and a huge mirror in space would end up getting broken up by space debris.

If I want to look at the world 20 years ago, I look at old videos, old pictures, history books. Sure seeing the world in the past would be a swell novelty, it's fairly useless...
 
With powerful enough telescopes, astronomers can see almost all the way back to the big bang, to the edge of the universe where galaxies and stars start to thin out, the time before matter, which could very well be the time before time. Astrophysics is the most mind bending stuff I know of.
 
Well, the scientists can see galaxies far away which we see from about a few hundred years away. So, i guess all you would see is a section of green and blue with clouds.
 
If I look outside now - it's night time I can technically see what happened xxx years ago when the light was originally sent from where evr the hell it came from?

So yes you can and cannot do as you suggested
 
Originally posted by 12sec. Civic

If the mirror is 10 light years away, the light from it that reaches us has taken 10 years to get from earth to the mirror, and 10 years to get back. So, if you looked towards that light with a high powered telescope you'd see the world 20 years ago. I am quite positive that we have telescoped that can see MUCH further than this in great detail.
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Your concept is correct, but the idea of "light" reaching this mirror from Earth, is not. See the only thing(s) that put off light in the uinverse are stars. Our planet may reflect "some" light off our star, but to see it from 10 light years away is impossible. It just doesn't put off that much light. The reason we get to see other planets so well in our solar system is because: 1) We are really (on a universe scale) close to them, and 2) Usually we are on the side that is reflecting the suns light. (These two ideas, can be applied to the moon as well) To this day, we still don't have really good pictures of Mercury, because all we see is a the shadow its casts when in front of the sun. (Although there was a semi-successful mission to Mecury in the 70's)


Originally posted by MazKid

You would only be able to see the planet as a whole, and a huge mirror in space would end up getting broken up by space debris.

Click to expand...

This isn't entirly true. Although the possiblity is out there, most likely it wouldn't happen. Space debris is soooooo far apart from each other, you could basicly stick something out there and almost promise it wouldn't get hit in your life time, nor your grandchilderns life time. Most of the big debris is charted wih orbits that Nasa keeps track of, and that now computers can predict when it might hit any given object in space. I think they have predicted Earth being hit in some 500,000 years from now. (don't quote me on that)


Originally posted by Viper Zero
We do have a mirror in space. It's called Hubble.
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This is our greatest acheivment as far as astromey is concerned. Recent pictures came in not so long ago, and the detail is amazing!

Originally posted by milefile
With powerful enough telescopes, astronomers can see almost all the way back to the big bang, to the edge of the universe where galaxies and stars start to thin out, the time before matter, which could very well be the time before time.
Click to expand...

This is what they are seeing with the Hubble, waves of clouds of dust and debris, expanding outward into what seems to be the truely unexplained.

If this stuff interests you, take an Astromey class, as I did just recently. The concepts will completly blow your mind. We think (as a human race) we know a lot when it comes to space, but as far as the true Astromer is concerned, we haven't even started to dent the iceberg!

So there is my science leason of the day! Hope I didn't bore anyone.
 
This is an interesting idea. The mirror you would place in space would have to be as efficient as they come (99.99999% of light reflected). Also, you would ahave to use Hubble (as it's the most advanced piece of stargazing equipment we have). Point hubble at the mirror, and theoretically you could see your parents' first meeting. I see no flaws with it.
 
Well, how about a slight adaptation to the question.


Screw the mirror. Send out a telescope like hubble that we could send out. That could look back at us. Then it could send the info as a radiwave which would take as long as light takes to get here.


The Voyager Space probes are 12.5billion km's and 9.5billion km's from Earth now. If they had a very powerful telescope on them (which they do) they could take pictures of earth.


The sad thing is. The Voyager has been travelling at over 35,000mph since 1977 and its only 10 light hours away from us. So, if it took detailed photos of City streets and stuff, that stuff only happend 20 hours ago. The pictures we receive would not be very old. Not worth it.


But the theory is technically sound.


PS: I just finished an Astronomy class at University.
 
The whole question is kind of general. Let me post a similar question, then then answer to it:

Can we hear the past?

Kind of, because some things move faster than sound. So when you hear the thunder, you're hearing the past of the lightning. But the real answer is no. It sounds strange, but you're not hearing the "past". Sure, you heard what happened then, but you're not constantly hearing it. It would be like saying when you hear your echo, you're listening to your past.

This brings me to my other theory. It is my theory of light and its speed. People say that light always moves at the same speed. This is light in general. I've been thinking specifically on this subject for a long period of time, although I havn't done any experiments or written anything down, I've been keeping track of things in my head and using logic. Let's say that you see a star through a black hole. What you see is two of the same image. Now that's because the light becomes bent when it goes around the hole. This also shows that light has mass, since it's being acted upon by gravity.
Since the black hole puuulls the light, it speeds light's speed half way through, but when light goes out, it slows the speed down. So therefore, light's speed is not constant.

Now I'll bring this back to relevancy. Here is another question:
If you watch documentrary footage of WW2 that was actually filming the war in 1943 or so, are you watching the past? No, you are watching something from the past. In order to watch the past, you would have to go back into the past and watch things from there, but then, of course, everything would be current there, so it creates a paradox.

Now I pose another question:

Many people claim that if you move faster than the speed of light, time will do one of three things: slow down, stop, or reverse. Others claim that none of that happens. Here is my reasoning for why it is not true. Look at the sun, what you are seeing is the light generated by the sun from 4 minutes ago or so, maybe longer, it's not relevant, just to know that there is a time difference. Now if you claim that if you move faster than the speed of light, then time slows down is wrong.

First, let me get something straight before I go complexe in my mind: lightspeed and the speed of light are two separate things. lightspeed is how fast light is travelling. The speed of light is a specific speed that all scientists have agreed upon so they can guage how far an object is away, hence lightyears.

Back to the reasoning:trouble::
Since black holes make light speed up then slow down, you're saying that light's time changes, when in fact, time is constant. Given, days and years, they're both variables for whatever planet you live on, by our definitions. A day is how long it takes for a planet to complete a 360º rotation on its own axis. A year is how long it takes to complete an orbit. Time would stay the same, however, because we've agreed to use seconds as our method of measuring time. We can say that Jupiter's day is this many seconds, or that Mars's year is this many, but we can't say how many years because it would be different by whatever planet you are on, and also by whatever calendar you use. So by saying this, you are saying that light is going back in time or its time slows down, because it's going faster than the speed of light when it enters the black hole. You're also saying that its time becomes slower because the light slows down when it leaves the black hole.
Now I'll bring this closer to the point:O:
When we say if we go faster than the speed of light, time will somehow change is odd. It's odd because then it would be saying light is instantaneous, which we know is not true. I'll bring something else to prove that light moves at different speeds:

When you shoot pure light through a prism, you see all of the different colours available. When you shoot pure light on to something, let's say a yellow wall, the yellow waves move, but all of the other colours stop. That's just it, they're not reflected, so either they change frequencies, which would mean their speed changes, or they just hault and we can't see them because they're not reflected back, so their speed halts all together.

If anybody would like to talk with me upon this subject, just PM me and we can chat:D

:O:O:O:O:O
 

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