Thread: A Question About Space And Light

the problim would be that the light may have been degrading over time, so, though we may be able to see into the past, it would probably be a very fuzzy picture.

... unless light only degrades in an atmosphere

you want to view what's happening on the earth's surface from 100 million light years away?.....

I think instant teleporting is the least of your worries, to be honest

what about 2000 years ago? I want to see these so called miracles for myself. If the red sea were parted, i want to see that too.

Im sorry, i dont mean to turn this into a religious argument.

I think a bigger problem would be if you angled the telescope slightly wrong

magnifying the sun's light down to a point and burning a hole in the back of your head


*edit*
but in all seriousness
I doubt you'd see anything at all

you're not talking about the sun's light, here
you're talking about the sun's light reflected off of the earth's surface
light bouncing off a surface will (I think) radiate out in a hemi-sphere

100 million light years away, the actual amount of light reaching your telescope would be so infinitely small, I doubt you'd see any light at all
let alone any detail in the light to constitute a "picture" of events that happened 100 million years ago

hey guys, i'm gonna move this to extended discussion i think.

Originally Posted by Hard

what about 2000 years ago? I want to see these so called miracles for myself. If the red sea were parted, i want to see that too.

Im sorry, i dont mean to turn this into a religious argument.
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no worries.

you would have to be very patent, though. It took about a day for the winds to blow the sea apart

Originally Posted by Hard

From what i understand about light years, it is the distance a beam of light travels in 1 earth year. Now for my question. If we could INSTANTLY teleport to a distance 100 million light years away from earth, could we look back at earth and see what was going on 100 million years ago (asssuming we had the proper telescope)?

I assume this is possible, because i have always heard that some of the stars we see at night may already be extinct, just that the last light rays havent reached earth yet.

but this will probably never be a reachable goal. Instant teleporting?......
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Yes you are correct. Theoretically that is possible, given that you can teleport and have the proper telescope as you said. It is the same way we can still look at dead stars on the sky at night.
We are able see the remaining light from a dead star, but the material emitting the light is gone.
This is all in theory though, as you can't teleport faster than the speed of light itself. At least I see that impossible when we are thinking in a materialized manner.
Other methods would be the use of wormholes, or 'warping' where you take advantage of the bending of the universe. It's all theories though, so we're merging theories with theories here .

I think it's great that you made this topic, since makes it easier to explain why time is only an illusion.

Technically what you say is possible. But you would need an incredibly powerful telescope, and you would need to be looking at the Earth at least from a location that is perpendicular to the plane of the Milky Way. Luckily the Sun is stationed in a relatively low density area of the universe, but even so, in order to resolve a clear picture of Earth:

9.46×10^15 x 100,000,000 = 206,265 (12,756,000) / alpha

You'd need a telescope precise down to 2.78 x 10^-12 arcseconds. (0.00000000000278) Or to about the trillionth of an arcsecond. The limit of our best space-based telescope now, the Hubble, can resolve 0.05 of an arcsecond. So you'd need a telescope about 20 billion times more powerful than the Hubble just to get a blurry picture of the Earth. I don't know what you'd be looking for on Earth 100 million years ago but don't expect to see extinct animals or anything without a telescope invented by God. But of course, if you had God, you wouldn't need to travel that far to see the past.

On another note, I believe a while ago a couple of British scientists managed to teleport a subatomic particle.

Light does diminish over distance, even in space. That's why scientists were so puzzled when they first saw Quasars. They first appeared to be starts, but they were MUCH farther away- past what was before thought to be the end of the known universe. There are probably plenty of stars out there, we're just too far away to see them.

If you had a good enough telescope and teleported from Earth, say, 100 Light years, you would see the Earth as it was 100 years ago. What we all see is light, reflecting off of objects, right? It makes sense to me.

Another question I'd thought of is how fast changes in gravity effect nearby objects. If the sun were to disappear instantly (Not possible, I know... in theory) would we fly out of orbit before the last rays of light finish their 8-minute path to Earth? Or would the changes in gravity occur AFTER we're flash-frozen?

Originally Posted by FreshBrains

Light does diminish over distance, even in space. That's why scientists were so puzzled when they first saw Quasars. They first appeared to be starts, but they were MUCH farther away- past what was before thought to be the end of the known universe. There are probably plenty of stars out there, we're just too far away to see them.

If you had a good enough telescope and teleported from Earth, say, 100 Light years, you would see the Earth as it was 100 years ago. What we all see is light, reflecting off of objects, right? It makes sense to me.

Another question I'd thought of is how fast changes in gravity effect nearby objects. If the sun were to disappear instantly (Not possible, I know... in theory) would we fly out of orbit before the last rays of light finish their 8-minute path to Earth? Or would the changes in gravity occur AFTER we're flash-frozen?
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i cant remember quite right but i think i read somewhere that the speed of gravity is the same as light

Originally Posted by docKnubis

i cant remember quite right but i think i read somewhere that the speed of gravity is the same as light
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http://www.newscientist.com/article.ns?id=dn3232

Originally Posted by Ynot

http://www.newscientist.com/article.ns?id=dn3232
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It does but the Earth would not fly away at the speed of light. The Earth is traveling at 30km/s in a mostly circular orbit around the Sun. Should the Sun disappear, the Earth will continue moving in a straight line at 30km/s along the line tangent to the point where it was in its orbit at the time of the Sun's disappearance. The entire acceleration provided by the Sun's gravity is currently directed in a centripetal fashion, keeping the Earth from moving in a straight line. (Like swinging a ball at the end of a rope above your head)

The last rays of sunlight would reach the Earth at the instant the gravitational effects of the Sun is lost upon the Earth (if you believe what they say in the article).

Originally Posted by Ynot

Light does diminish over distance, even in space. That's why scientists were so puzzled when they first saw Quasars. They first appeared to be starts, but they were MUCH farther away- past what was before thought to be the end of the known universe. There are probably plenty of stars out there, we're just too far away to see them.

If you had a good enough telescope and teleported from Earth, say, 100 Light years, you would see the Earth as it was 100 years ago. What we all see is light, reflecting off of objects, right? It makes sense to me.

Another question I'd thought of is how fast changes in gravity effect nearby objects. If the sun were to disappear instantly (Not possible, I know... in theory) would we fly out of orbit before the last rays of light finish their 8-minute path to Earth? Or would the changes in gravity occur AFTER we're flash-frozen?
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Light diminishes in space in the sense that it is spread out at the rate of an inverse square relationship with distance. Interstellar dust/dark matter is what causes most of the actual diminishing.

Also, I don't know what you mean by flash-frozen but the Earth has an atmosphere so I don't believe there will be an "instant-freeze" effect. I'd give Earth a few weeks before it becomes completely inhabitable and perhaps a few months before humans will be unable to survive without burrowing deep into the crust.

I'd assume the Earth/Moon system would still be intact, allowing for continuing plate-tectonics, geo-activity etc to fade slowly, so maybe we could survive for a longer period than that by living underground, until we run out of food.

The problem here is how we measure it... seeing as how earth "years" are irrelivant in the long run. They are just man made integers, used to comprehend the ellapsing of existence over your present self.

One thing overlooked though, you cant teleport.... you are made of particles, and to get 100, 000 light years away in an instant, your particles would have to travel faster than the speed of light(at least within the realm of current physics), which is impossible.

You could theoretically travel at 99. 999999999999999999999% the speed of light, then you could look back and just barely glimpse yourself leaving, and then you could watch what happens while you were gone.... That seems pretty interesting too..

in theory, yes: the light from earth that would reach you would be 100 million year old. Only I don't think you will see much A lightyear is a Looooong way.