It is possible to see our past from deep space
76From elsewhere in the universe, it is possible to see the Earth's past
This is a small, edited part of another Hub I have written, "Extraterrestrial Life - Will we Ever Find It?".
It is a on a particular subject I find so fascinating that I wanted to do a separate little Hub about it.
Light travels faster than anything else yet known to humankind; its speed is 300,000 kilometres, or 186,282 miles, every single second; the Earth is 93 million miles away from the Sun, and even at its immense speed, the Sun's light takes 8 minutes to reach the Earth. The most distance planet, Pluto, is 4,000 million miles from the Sun, and at 186,000 per second, the Sun's light takes 4 and 1/2 hours to reach it.
Because the speed at which light travels is limited, it is impossible for us to see anything in the universe as it is now; we can only ever see things as they were.
The light from the Sun carries the image of the Sun to our eyes. That light takes 8 minutes to reach us, so we can only see the Sun from Earth as it was 8 minutes ago. The Moon, our natural satellite, has no light of its own, it is illuminated by the Sun; the Moon is approximately ¼ million miles away, so the reflected sunlight that carries the image of the Moon to our eyes takes just under 2 seconds to reach us. When we look at the moon, we see it as it was just under 2 seconds ago.
The fact that the speed of light is limited has very interesting implications. If it were possible for you to be on the surface of the outermost planet, Pluto, and you had a gigantic optical telescope powerful enough to look back and see things on Earth in fine detail, you would be able to see things that had happened four hours earlier, because that’s how long the reflected light carrying the image of the Earth would have taken to reach you.
If you could travel far enough away from the Earth, you would be able to see many of the answers to past mysteries. You would be able to find out the truth about how the pyramids were constructed, or exactly what happened to the dinosaurs.
In order to instantly travel to another point and time in the universe, and see the Earth's past, you would need one thing that only exists in science fiction, a Star Trek type time-warp spacecraft, and another thing that is only hypothetical; an optical telescope many times bigger and more powerful than any ever built. A time warp spacecraft does not exist, and neither does a telescope powerful enough to see things in fine detail over such immense distances; but if they did, looking into the distant past would be perfectly possible.
There would be a couple of potential problems to consider.
You might be able to get a clear view of things that happened on Earth up to several hundred years ago from a distance of several hundred light years out; go much further out, and depending on what location and direction you were looking back from, interstellar gas, dust and light from other stars might get in the way.
To get a clear view into the Earth's very distant past, you would have to find a point in the universe where you weren't looking through a lot of stars or interstellar/intergalactic matter. That could be a position outside the edge of the galaxy (The Milky Way) from where there was a clear line of sight. If you looked back from the centre of the galaxy, about 30,000 light years away, where stars, gas and dust are very dense, you probably wouldn't be able to see the Earth's surface clearly.
Another little problem with looking back to see the Earth's past from far out in space would be our old friend, the weather. If the assasination of Julius Caesar took place on a clear sunny day, then you would be able to look straight down on it from 2,000 odd light years away; but if it took place on an overcast day, then tough luck, you'd be looking down onto the top of a cloud bank!
Fascinating isn't it? Just think - if you suspect your husband or wife was having a quick kiss and cuddle with your neighbour last summer, you could hop on your time warp craft, travel half a light year away, and use your super telescope to look down on them in the back yard. Before you go rushing off to the divorce court though, you would need to consider if they would accept evidence from six light months away!
Copyright David Sakho, 2011
Hypothetical time warp spacecraft
Space telescope
Satellite image of the American Civil War battlefield at Gettysburg
Satellite image of the Acropolis, Athens
Satellite image of the Giza Pyramids
Satellite image of Dinosaur National Park, Alberta Canada
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It is an interesting hypothesis but unfortunately, for us, could only be a though exercise. Whether we are looking out into the universe at another planet or "they" are looking back at us we will both be limited by time. Theoretically, as you point out,we could observe their origins and they could observe ours. Good hub....thought provoking voted up.
Davidwork, very interesting hub. This idea can only work up to a certain point. The Milky Way galaxy is 100,000 light years across so theoretically speaking, if you are on a planet on the other side of the galaxy and had a very powerful telescope you will be seeing images that happened 100,000 years ago on Earth. But that is as far back as you will be able to see because the nearest galaxy is 2.5 million light years away and we would only see the galaxy and not the individual stars that it contains if we were located in the Andromeda Galaxy. Unfortunately, we will not be able to see the dinosaurs and when they were destroyed because that happened about 65 million years ago.
Melpor,
Thanks for your comment, though I think you did miss a couple of points I made; this is all hypothetical, though the part about the light is correct. I put this Hub up to get people thinking.
I did point out that you would need a time warp type spacecraft to get to a particular point in the universe and look back; and I did also point out that you would need an optical telescope BIGGER AND MORE POWERFUL than anything now in existence.
If such an optical telescope were possible, why wouldn't you be able to look back 65 million years if you had a clear line of sight?
The largest optical telescopes we now have are looking at objects several BILLION light years away, at the known limits of the observable universe. If they were a lot bigger, and had greater resolution power, why wouldn't they be able to distinguish detail from such a distance?
Great blog David. I have enjoyed reading this piece a lot more than your previous "E.T. Life" hub as I've learned much more about a topic that I'd not even begun to think about in this way before. You really do seem to have a clear set of perspectives on the ramifications associated with this phenomenon.
I was wondering though - as I don't know anything at all about this subject - if the fictitious concept of a time machine (as depicted in the 1960 Rod Taylor movie) would similarly be based on the same principles as, say, the design of the timewarp spacecraft you mention? If this is true then wouldn't it be possible to shift to be present at the actual point being observed by the telescope as opposed to just looking on from a distance?
I really have no ideas of my own on this and genuinely look forward to picking up on an interesting response.
Jags,
I’m sorry I didn’t answer your question immediately.
I had to take my time on this one and write an answer that hopefully, explains things clearly without over simplifying them. I hope the analogies I have used below do this adequately.
Time travel, as demonstrated in H.G. Well’s 1895 novel “The Time Machine”, and the 1960 MGM film of that book starring Rod Taylor, is a bit different from the concept of time warp travel.
Time travel is about simply travelling to the past or the future.
Time warp travel, sometimes also referred to as warp time or wormhole travel, is a THEORETICAL way to overcome the vast distances of the universe using technology that enables you travel from one place to another in a much shorter time.
Any journey you make, no matter where to, involves two things that you cannot avoid: time and distance.
Suppose you go around to your friend’s house. It’s only a few streets from you, but however you decide to go there, whether you walk, cycle or drive, you cannot avoid dealing with time and distance. The distance remains the same if you take the shortest route, but the time to get there depends on which method of transport you use.
Suppose you want to make a longer journey. You’re in the UK, and you want to go to Australia. That’s about twelve thousand miles. If you decide to hike there, it could take you several years. If you decide to drive overland, across Europe and Asia, it could take several weeks. If you do what most people would do and fly there, it only would take 16 – 18 hours. Now I have to be careful here, but the jet is the best comparison to warp time travel; by using it, you have, in a very basic way, ‘warped’ the time. By using flight technology, you have cut a journey that would take several years overland to one of less than a day through the air.
If you want to travel from one place to another in the universe, you also have to deal with time and distance, but on a much bigger scale, because the universe is unimaginably vast.
Our best rockets have sent astronauts to the moon and have sent probes to almost all of the planets, but for deep space, they are very slow and basic. They may seem fast to us, but the distance to even the nearest star after our sun is so great that a rocket would take about 40 thousand years to get there, and of course, humans could not survive a journey that long. Even light, which moves faster than anything else yet discovered, 186 thousand miles every second, would take about four years to reach the next nearest star. If humans developed a spaceship that could travel at light speed, it would still be an eight year round trip.
It would be impossible for us mortal humans to survive long journeys through deep space to other parts of the universe without death, ageing or some kind of trauma.
The Great scientist Albert Einstein applied his genius at physics and mathematics to work out that it is possible to bend, or warp, space and time, and other scientists who followed in his footsteps believe that this may make travel to other parts of the universe THEORETICALLY possible IF we can develop the technology to do it in the future. That would mean that instead of taking tens, hundreds or thousands of years to travel from Earth to other stars and solar systems, it could be done within a reasonable time, hours, days or weeks, which would be more suitable for us mortal humans.
As for being able to jump back to the time period you are looking at, no, you wouldn’t be able to do that, because remember, what you would see would only be an IMAGE of the past that the light has carried to your eyes, not the past itself. That is easily explained by using the Sun as an example; astronomers who specialise in studying the Sun see it through their special telescopes every day. Because light from the sun takes eight minutes to reach the Earth, they can only SEE the Sun as it was eight minutes earlier, they cannot TRAVEL BACK IN TIME eight minutes just by seeing that image. Here’s another analogy: your friend has just seen someone you haven’t seen for ages. He decides to go around to your house and tell you in person. It takes him about ten minutes to walk to yours. When he knocks on your door, he is telling you about something that happened ten minutes earlier, but you can’t travel back in time ten minutes to actually witness what he has told you, can you?
This is the best way I can explain it. Maybe some other Hubbers who are real science buffs could drop in with comments that could explain it better.
Cyndi10 Level 7 Commenter 5 months ago
Interesting hub and interesting premise. I think they are developing or asking for funding to develop a telescope that is supposed to come close to allowing us to see the big bang!