Can you see Earth in the past from a telescope?

[ufomaybe]

If you can design one powerfull enough that was on another planet on the other side of the universe, can you see the ground level on Earth and all the different types of people who lived here on a clear sunny day?<br /><br />Can we ever do this in future ourselves assuming we can warp to other side of universe somehow in and instant and have the future technology.<br />

 

[vogon13]

20,000 lightyears (still in our galaxy, btw) would take you back in time 20,000 years.<br /><br />But getting you 20,000 lightyears away instantaneously is a problem.<br /><br />The size of the telescope would be biggish too.<br /><br />The earth's atmosphere would limit the ultimate amount of detail you could see regardless of telescope size.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[ufomaybe]

This say would be a great way of knowing weather the dinasours were really knocked off by an asteroid.<br /><br />Wouldn't the earth be clouded in all dust from the asteroid? <br /><br />Just an idea!<br /><br />Seems we are not allowed to go back in time and look for whatever reason.

 

[vogon13]

You would see (theoretically) a world full of dinos, than a big impact, then many clouds and dust and smoke, and then (presumably) a planet devoid of dinos.<br /><br />Aperture of the scope fot this at ~70 million light years would be immense.<br /><br />Aiming the scope would be difficult.<br /><br />Determining your location accurately enough (to watch the exact day of the impact) you would have to be within 10 billion miles or so (sounds big, but it is not).<br /><br />I am assuming lugging around the telescope won't be easy . . . <br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[qso1]

No way to answer that question with any real accuracy but to consider a more near term possibility. Think interstellar mission to Alpha Centauri that looks back at our solar system and you'd see the Earth theoretically anyway, as it was almost five years earlier. Optical physics and Earths atmosphere would probably limit the ability of the scope to see anything more than a globe where continents and clouds would be visible but not details such as cities, much less people. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[brandbll]

This plan is brilliant! I am taking note of it and will forward it to people whom it may concern. Thank you. <div class="Discussion_UserSignature"> <p><font size="3">You wanna talk some jive? I'll talk some jive. I'll talk some jive like you've never heard!</font></p> </div>

 

[doubletruncation]

Or you could put a satellite up in Earth now, record what's going on on the Earth right now (with much more ease than you could from another star system) and watch the recording five years from now (or however long from now you want to watch it). Unless you can travel from here to another star system faster than light does (given our current state of knowledge, there's no reason to think that you can, and some reason to think that you can't) this method would always beat out traveling to another star system to see the Earth in the past. We could always hope though that there is/was some kindly aliens recording the Earth from some distance away, that they'll keep this recording until we might meet up with them, that we do eventually meet up with them, and that they'll share the recording with us in a form that we can understand. <div class="Discussion_UserSignature"> </div>

 

[qso1]

doubletruncation:<br />Or you could put a satellite up in Earth now, record what's going on on the Earth right now...<br /><br />Me:<br />Certainly easier than waiting the couple centuries or more that it will probably take for us to become an interstellar travelling species. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[xmo1]

Yikes. Yes <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

 

[ford001]

What a great question.<br /><br />I have been thinking about just this same thing for the past couple of years.<br /><br />I have taken an interest in early hominids, and have been wondering about a way to be able to peer into the past, and see what early human and prehumans were doing and how they lived.<br /><br />The telescope sent out 2-5 million light years and looking back at Earth is something that I have fallen asleep to thinking about many nights. <br /><br />Glad to see I'm not the only one thinking about these things. <img src="/images/icons/smile.gif" /> <br /><br />You got some very good replies to this. Something more to think about now........

 

[vogon13]

To emphasize, for this to work, you need an instantaneous drive (or something at least seriously faster than light) and an enormous aperture. <br /><br />Just discerning weather patterns on earth from 2-5 million lightyears away is a staggering task. Making out life forms on the surface is vastly more difficult.<br /><br />Could you spot a cold virus on the visor of an astronaut on the moon from earth? This 2-5 million ly thing is hideously more difficult.<br /><br />Also, the stability of your telescope and the aiming accuracy would be daunting. How closely will Heisenberg allow you to point the telescope? And how do you refine your aiming? What was the identifiable configuration of stars in the earth's vicinity that long ago? How could this thing be pointed accurately? <br /><br />How many mamoths can you line up head to tail in a circle 5 million light years across? {think about it}<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[ford001]

I realize that this is just mental gymnastics, and is not really a workable idea, at least not with our present technology. <br /><br />(Why do you think it puts me to sleep while thinking about it? Trying to work out that faster than the speed of light, problem, man, if that doesn't put you to sleep, nothing will <img src="/images/icons/smile.gif" /> )<br /><br />But, to me, it's still an interesting thought as a way to look back in time......

 

[torino10]

Does light bend around a black whole? I know light doesn't bend, space does, but you get my meaning I hope.<br /><br />If you knew where a black hole was you could look into our past without needing a way to move faster than light.

 

[doubletruncation]

<blockquote><font class="small">In reply to:</font><hr /><p>Does light bend around a black hole?<p><hr /></p></p></blockquote><br /><br />Yes it does, your idea is pretty neat I think. It's kind of like looking in a mirror I guess (which is another way to see how you looked in the past <img src="/images/icons/smile.gif" />). <div class="Discussion_UserSignature"> </div>

 

[doubletruncation]

I would guess that it would be very difficult, if not impossible, to look at a distant black hole and hope to see what you looked like in the past. Any light that came from you and is now on the way back to you would probably be completely scrambled with light from all sorts of directions. I'd also imagine that the target area around the black hole for light that would come back to where you are now would be vanishingly small, meaning that you'd be talking about a very tiny amount of light that's actually from you mixed together with light from lots of other directions. <br /><br />See for example some of the discussion near the bottom of:<br />http://www.astro.ku.dk/~cramer/RelViz/text/geom_web/node3.html <div class="Discussion_UserSignature"> </div>

 

[ufomaybe]

Yeah I never seen this question asked online until I posted it. I figure I ask it here.<br /><br />Well also you know if we ever met an alien race from far away and they did have the technology, they maybe can answer our question if they looked back on Earth from where they are as to what happend thousands of years ago.<br /><br />Noahs ark? Great flood? Jesus? Romans? Would be nice to look back at that stuff.<br /><br />Though like most said its probably not possible for now if ever.

 

[alokmohan]

Tell me something of instantaneous travel please.Are we making absurd theoritical speculation?

 

[vogon13]

Einstein had concerns about objects traveling faster than light. An instantaneous drive doesn't involve speed at all (think about it).<br /><br />If you appear somewhere else in zero time, you have not traveled sequentially through the intervening points.<br /><br /><br />{btw, this is my first post today, it is very early (for me) and I might have a different take on this when I'm awake}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

Analogy:<br /><br />On your PC you can click on and drag an icon around. Seems like one could get in the operating system and just cause something to print out on the diplay in a different location in one screen refresh interval, and not drag it there.<br /><br />Perhaps an instantaneous drive just redefines you as being somewhere else in 1 Planck time interval. Since motion is not involved, you could be anywhere in the universe in 10^-43 seconds . . . . <br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>