Seeing into the past

I dont belive that its possible to time travel in to the past or future.
But maybe to see into the past?

Think about this:

It takes 8 minutes from the light from the sun to reach earth.
That its self is looking back in time to whats happened on the sun.
If it dissaperd, you wouldnt know till 8 minutes after it dissaperd it was gone. following?

Lets say theres a planet with a good clear view of us with unbelivebly powerful telescopes. to zoom in even farther that you can on gogle earth lol


If that planet looked at Earth they would see our past through the light because the delay in the light has took so long to travel the distance to them.



Imagine that planet was a mirror instead (yes that you see yourself in) in space that reflected light of our own plant back to us and we luckly pointed very powerful telescope (yet to be made) at it. We would actualy see our own past also.



so as an example.

Its the year 0

light comes from the sun, bounces off earth to the mirror takes 100 years. Light from the mirror back to the earth and in to telscope the same time 100 years. We would see what would happen in the year 0 but have to wait till the year 200 to see what happened because of the time it took for the light to leave us and get back.

Pretty good idea. I know the idea of a mirror in space is mad, let alone somthing to zoom in so far this day and age. But its still possible for if you were on another planet haha

If ive got anything wrong in what ive thought. Do correct me.

Nope, it's all correct.

It's weird to think that for every second of earths existence, there is light travelling away that would show you what it was like then.
Of course, the further in the past you went the more powerful telescopes you would need, plus to get that information back to earth would require the exact same amount of time that you are looking back, but it would be plausible if we were advanced enough.

How's this for a trip-

If you had a faster than light engine and an arbitrarily good telescope, you could warp out far into space and watch the entire history of the earth as far back as you wanted.

OMG!! You're so clever! and, there was a thread on here not long ago about how scientists had found a way to manipulate radio waves to travel faster than the speed of light!! maybe these two ideas could be connected somehow!

OP, you should find the scientists and pitch them your idea!

I am not sure people know the past correctly.

I'd be willing to help out in what I think they are missing.

Would going back in time help us find out life's mysteries?

Like where the UFO came from.

Or... rather than setting up a single mirror 100 light years away, you could set up a series of mirrors in a zig zag pattern that reflect the light back and forth... reducing the overall distance needed from one planet to another.

If I remember correctly, scientists got light to slow down (or something like that). I wonder if your idea was the general principle used.

Every moment since the big bang, there has been a "foot print" left behind. So in theory, it is possible to go back in time, however going forward still has ideological kinks.

AAC

[edit on 9-5-2008 by AnAbsoluteCreation]

Originally posted by AnAbsoluteCreation
Every moment since the big bang, there has been a "foot print" left behind. So in theory, it is possible to go back in time, however going forward still has ideological kinks.

AAC

[edit on 9-5-2008 by AnAbsoluteCreation]

What? Going forward in time is easy. I for one, do it all the time. it's slow, but I can manage 1 second per second with no effort.

Going backwards in time is the hard part. Sure you can see light from the past, which lets you watch the past of some other places play out in real time, but nobody has a way of actually moving things back in time. Faster than light travel necessarily implies that, assuming relativity is correct.

And we have more solid evidence for relativity than we do for causality. so there's good reason to suppose that if FTL travel was ever invented, it would also function as a means to go back in time.

I always consider pictures, video footages and so on "looking back in time". But that is with devices capturing the event from one (or multiple) angles, manipulating and "recording" so in the "future" we can look back at it. So yeah, why not find a way to capture all the "past".

However, if light is emitted out from a specific object inside a cave, would you still see this light somewhere in the far far far away universe? After all, this "light/past" did not leave Earth at all...

Look at it this way.

You are now using light to send and receive this data on this thread. Fiber right? Everything is encapsulated in small chunks and opened and reassembled into the proper order so you see this. It's a very simple process when you break it down.

Remember, you're not actually seeing this your seeing a representation or a clone(reflection) of the original sent by light. You are also looking into what I wrote in my past from my perspective and presently in your perspective.

Now, we know for a fact that we can slow light down somewhat.

In theory (maybe fact) we can also speed light beyond normal light speed.

While we cannot physically travel into the past we could in theory send data into the past and possibly find a means to reflect it back containing data from the past. (as in the op's mirrors)

At some point we could send & receive enough data to build a virtual reality machine that would itself be a time machine - however our physical bodies would never leave our time - only our minds through the interface could see the past. (another words the time machine would be virtual reality interface into the past)

At some point we could devise a means for others in the time we are viewing/visiting (reflecting) to receive our data as well and thus we could manipulate time through them or through items would could manipulate with photons (like a television or maybe even someones brain).

Even though would could not physically be there our virtual time machine would allow us indeed have some actual manipulation power though very limited, mostly it would be for viewing.


[edit on 10-5-2008 by verylowfrequency]

Originally posted by IchiNiSan
However, if light is emitted out from a specific object inside a cave, would you still see this light somewhere in the far far far away universe? After all, this "light/past" did not leave Earth at all...

Yes, the less light the more difficult it would be. Which is why the more reflexions you create the more likely one could see you in the past. Each reflection would make another viewpoint possible because there would be more light able to be captured.

Maybe that's why mirrors are connected so much with magic - they are connections or multipliers.

Originally posted by IchiNiSan
I always consider pictures, video footages and so on "looking back in time". But that is with devices capturing the event from one (or multiple) angles, manipulating and "recording" so in the "future" we can look back at it. So yeah, why not find a way to capture all the "past".

However, if light is emitted out from a specific object inside a cave, would you still see this light somewhere in the far far far away universe? After all, this "light/past" did not leave Earth at all...

Nope. It hit the cave wall and was absorbed as heat. You can only see what went on on the surface of the heavenly body in question from space. Anything that went on out of line of sight of the great outdoors is lost forever to the past.

Not that its particularly likely we'll ever get engines fast enough or telescopes powerful enough to watch the distant past, but hey, it's good for a thought experiment, right?


Now: Mirrors won't help, unless they're angled so that light that would previously hit something is now reflected into the sky. Otherwise, it will absorb about 15% of the light and then reflect the rest into a wall or something.

Note that when scientists slow light to a crawl, they're not actually slowing the photons down; they're just forcing the light to take a very long and convoluted path through a material. In certain supercold vapors, they can slow it to a paltry few meters per second, but that's just the speed of the light pulse through the materials. The photons themselves still travel at c. It just has to pass around all the atoms in the material, or be absorbed and remitted, and so it takes significantly longer for the light to reach the other side than if it was traveling through a vacuum. It might have applications in storing data as light pulses, which is pretty cool.

You'll note that light is slowed by anything that isn't a vacuum. light travels slower in water than in air, and slower in glass than in water. The speed of light in a material determines it's index of refraction. The speed of light given in textbooks is the speed of light *in a vacuum*. There is no credible current theory involving ways to make light travel faster than that.

Although what verylowfrequency said would make for a bitchin' transhumanist science fiction story. Things like that usually involve sending data through wormholes into alternate universes to build a place that we could put our minds, but doing the same thing to our own universes' past is cool too.

reply to post by mdiinican


Thanks for the lesson about photons not slowing down. I always assumed they slowed down and not taken longer paths. Never had a physics course.

I'd just be happy if someone would reflect next weeks Mega Millions number to me. Maybe they could bounce it off the mirrors on the moon.


[edit on 10-5-2008 by verylowfrequency]

Originally posted by verylowfrequency
reply to post by mdiinican

 

Thanks for the lesson about photons not slowing down. I always assumed they slowed down and not taken longer paths. Never had a physics course.

I'd just be happy if someone would reflect next weeks Mega Millions number to me. Maybe they could bounce it off the mirrors on the moon.

[edit on 10-5-2008 by verylowfrequency]

Well, by any rights, you could use the technique of putting a mirror somewhere (far out of the solar system!) to get *last* week's mega millions number. You could use a mirror on the moon to see yourself circa a fraction of a second ago. light takes about sixteen minutes to the sun and back, about fourty for a round trip to mars.

Another neat fact is that you can fire stuff through substances faster than the speed of light in that substance. This is most common with particle radiation in, say, water. It often gives off a pretty, eerie blue glow, and is called Čerenkov radiation. It's what gives operating nuclear reactors their characteristic blue glow. It's mostly UV though, so it's best too look at it in pictures only. Not that it's a great idea to be in the same room as the fuel rods of an operating nuclear reactor in the first place.

The particles aren't going faster than light, they're just traveling through the material faster than light does. the photons interact with the substance as they pass though, whereas particles literally brute-force plow their way though, only stopping when they run into something.