The Earth completely vanishes in an instant, leaving behind all of its artificial satellites.

The Science bit:

We know that large masses warp space.

The Question(s):

What would happen to the satellites? Would space spring back instantly in response to the Earth's disappearance? Would this in turn cause the satellites to rocket away from their respective positions? Would perhaps the effect be nominal due to the Sun's own warping of space?

It might help to use the standard "heavy ball on a taut sheet" scenario that is often used to visualize the warping of space.

What do you think?

Anyone ever read a story or scientific paper that discusses anything like this?

Thanks!

-HSO

***

In the answer, I'm ignoring the sun... Hope that's what you meant. If the Earth disappeared,
then the effect on spacetime would propagate away from the place where the Earth had been at
light speed. So, the artificial satellites would continue to go travel in orbits around where
the Earth had been for the time it would take light to get to them from the Earth (a very short
time, but not instantaneous). If the Sun disappeared, the Earth would continue in its orbit
about where the sun had been for eight minutes, the time it takes light to travel from the sun
to the Earth.

One upshot of relativity is that nothing, including information, can travel faster than light.
If our orbit around the sun changed instantaneously, so that we could work out that before those
8 minutes were up that the sun had disappeared, that information would have reached us faster
than light - not allowed.

Once the effects of the Earth disappearing had reached the satellites, they would travel in
straight trajectories, in the directions they had been travelling in when the effect of the
Earth disappearing reached them (as I said, I'm ignoring the sun).

-end
[EDIT]

And then he responded with the following after I asked to include the sun as a variable:

***
Following the "distortion of spacetime" picture, if the Earth disappears then the region of
spacetime around the Earth, which was distorted, will return to being flat (or whatever shape it
would be, taking into account nearby masses). However, the flattening effect would spread out
from where the Earth was at light speed, so regions of spacetime too far from the Earth to be
effected at any moment will still be distorted as if the Earth was still there. So, the way that
spacetime reacts is to flatten out, but not instantaneously.

Once the spacetime is flat in the region of an artificial satellite, it will just follow a
straight trajectory, and head off into space on a straight course.

Bringing the sun into play, all of the satellites of the Earth are also in orbit around the sun,
and none of them would have sufficient energy to escape the sun's gravity. So, once the Earth
has disappeared, the satellites will either fall into the sun or settle into independent orbits
around the sun, and it's critical on this front which way they were going when the Earth
vanished. Satellites that happened to be heading straight towards or straight away from the sun
would just fall into the sun, but satellites that were heading sideways on to the sun would
settle into an orbit around the sun. Anything in between would probably result in an eccentric
orbit. I think.

[This message has been edited by HSO (edited January 18, 2005).]

The fact of the matter is that while I understand the concepts of relativity, I truly know very little -- maybe enough to be considered "dangerous". I wouldn't be able to predict the results of such an impossible/implausible thing occurring. But in the theoretical sense, I'm interested -- merely as an aside to what I'm working on storywise.

The thought the popped into my head was: From an astronaut's perspective on the ISS, for instance, what affect would this have on their craft, technically a satellite. The answer is: I dunno. I have my suspicions; none of which are rooted in actual science.

Go here http://www.cuug.ab.ca/~kmcclary/ORRERY/example.html then click on start, then click on Destroy, to take the Earth away and leave the moon.

Pretend the moon is one of your satellites, and run this model multiple times to get a feel for what happens.

Still, I have a faint inkling as to why Einstein's hair was as it was. G-Relativity is heady stuff. It boggles, it does.

Well, you know when you're just about to fall asleep and you reach a near or full hypngogic state? Ideas pop into your head at random, your body relaxes, and eventually you fall asleep.

Two nights back, I was in that state, just before sleep and the craziest of crazy ideas popped into my head. This was it. What would happen if the Earth just disappeared? Of course, I've taken it further than that -- it doesn't simply disappear -- it goes somewhere else. But the space it occupied is now empty. And for my story, I've decided that the moon comes along, but no of the artificial satellites. This way I don't have to deal with tidal effect on Earth, saving me from that aspect of science.

As to who did it and why and how... for the purpose of the story, it's not important -- I'm allowed one really crazy idea. But if you will, think of it like the Greek Gods messing about with humanity for their own purposes, bets, what have you, and now put in on a universal scale.

There's a lot more to it than this, but that's the general gist.

This topic is merely an aside and a curiosity. It would be a separate story, maybe. Because the other thought, which I alluded to earlier, was "hey, what about the guys on ISS?" They would be stranded. But if I were to write about that, I would need to know a lot about physics and science. Thus, this topic -- hoping to cull that info from those more knowledgeable than I am.

The Earth is orbiting the sun at approximately 30kps. The lowest stable orbit around Earth has an orbital velocity around 8kps.

The moment the Earth disappears, you calculate the satellites' orbital velocities relative to the sun, rather than relative to Earth. Even if at that moment a satellite's oribit around Earth was taking it directly opposite to the Earth's orbital motion, it would still have an orbital velocity around the sun of 22kps.

So there's no way a satellite will be "heading" directly toward (or away from) the sun.

The satellites will take up orbits of varying eccentricities around the sun based on their vectors at the moment the Earth disappeared. None of those orbits should intersect the sun, so all the satellites are likely to survive for a long time.

If we are too assume for the sake of the story that superhuman entities used some mysterous means of teleporting the Earth and its moon away...

The mechanism of mysterous means might cause unusual repercussions for its dependent satellites. For instance, aside for the gravitional waves caused by the sudden absense of the masses which curve space-time, what kind of space-time repercussions would the mechanism cause?

The paths the remaining objects take in space-time might be altered depending on the mechanism. Say a giant wormhole appears, selective enough to swallow the Earth. For a time the satellites might rush toward the wormhole, until the wormhole dissipates.

Or perhaps, we assume there are other planes stacked in a higher dimension or dimensions, if the Earth was move from one plane to another, it might have a different effect.

Since its fiction, said mechanism might have any effect you want to make it. As long as it sounds credible.

I guage from your comment that only artificial satellites remain (earth and moon left together) that your interest is in the survivors on the ISS or a similar facility.

They would die from lack of oxygen or food long before the issue of them hitting a planet or the sun became a factor.

Now if you are setting this in a period where they can maintain themselves in their artifical world for years then you might have an issue of them being captured by Mars or Venus or eventually falling into the sun.

By the way, let's assume that all known laws of physics apply except for the fact that the Earth just disappears.

Good brainstorming, Chris. I'm trying to avoid the wormhole thing, though you can bet that characters in the story will consider that. But a wormhole still requires that it be traversed or travelled. In this case, the Earth is simply in one place one second, and in a new place the next. Which is all I'm really after... just the fact. The how and why don't really matter. It just is.

The astronauts are in free fall around the Earth. When the Earth disappears, they instantly change to being in free fall around the sun. And free fall feels like free fall.

Now, if you're thinking of the rubber sheet analogy, you may have the impression that there would be a "snapping back" of the rubber sheet as the weight which was holding it down is instantly removed. But while that snapping back would be very apparent to a three-dimensional observer, you must consider it from the point of view of a two-dimensional observer on the surface of the rubber sheet.

Obviously, the snapping back in the third dimension is not observable in two dimensions.

However, the curving of the rubber sheet has did cause some distortions in two dimensions, and smoothing the sheet will eliminate those distortions. But such distortions always seem to be away from the observer -- even though the spacetime where the observer is located may be distorted, the observer is distorted as well, so the observer does not notice.

Imagine a square drawn on the rubber surface (when flat.) When something nearby distorts the rubber sheet, an outside observer can see that the square is distorted, but the square still thinks it has four sides of equal length and four right angles. When the distortion is removed, the sheet snaps back to smooth, and the square doesn't notice that its own shape has changed, although it may notice the effects of the change on distant objects it has been observing.

Secondly, I want to ensure that I've understood correctly:

Simply, there wouldn't be any perception of the event except for visually? In other words, as Eric said, they may notice the amount of light has changed since the Earth is no longer reflecting any sunlight, and that the Earth is no longer there if it were being viewed from a window at that very moment, but no physical force would be apparent on the spacecraft.

Naturally, any computer uplink/downlink would be severed at the moment, too, so surely some sort of alarm would go off to indicate this.

So, really, the event itself would be rather boring and mundane from the physical phenomena perspective.

Correct?

His descriptions of thing happening are simple and easy. They involve someone pushing a button and everyone watching in amazement as "the Black Fleet vanished." Or, "The Moon was gone."

The description of what has happened is: "They were annihilated." Apparently, the device destroys stuff so thoroughly that there is no smallest atom remaining in "our universe" and sends it somewhere outside of space/time.

An interesting device indeed.

You might check some of the Amazon stores for the book, there were originally three: "Legion of Space"; "Cometeers"; "One Against the Legion." IMHO the first one is the best one. They are in similar vein to Burroughs "Martian Tales" (Not "Martian Chronicals"). Basically coming from the old swashbuckling days of Adventure and Wonder SF, (when there was a lot less science and nobody let it get in the way of a good story. )