What would happen if we shrink earth?

Question

I just watched one episode of Avengers Infinity War series, in this episode AntMan manages to shrink earth, and everything it conains (People, Animals, Things, etc.) into a (I believe) microscopic level.

Now, assuming this is possible, what would happen to us? How we, tiny people, will be affected by the gravitational force of the moon, and Sun?.

Trying to rationalise super-powers is generally futile. In this case, we have no idea how the shrinking works, so all we can do is make stuff up, which is not what you asked for by using the reality-check tag. Here's a tip: comics writers don't create rules for themselves. They just make up whatever suits their plots. — John Dallman, Sep 22 '16 at 21:18
I'm going to float the idea that this be closed as "too broad" unless the OP is able to clarify how this shrinking process works. Making atoms and subatomic particles smaller has a significantly different answer path than declaring that, for example, every second molecule is sent to some other dimension. Note as well that the latter option itself would introduce a whole host of additional clarifications needed. Alternatively the question could be re-stated to specifically state that the act of shrinking did not occur and that the Earth and people on it were simply much smaller. — GrinningX, Sep 22 '16 at 21:54
See also: What we gonna see if we start to decrease in size infinitely? and What issues as a result of square-cube law would a human scaled to the size of an ant face? — Theraot, Sep 23 '16 at 01:32

score 2 · Answer 1 · answered Sep 23 '16 at 01:18

We need to check if Earth would become a black hole. To do that we calculate the Schwarzschild radius for Earth mass. If Earth becomes smaller than that, then it is a black hole.

So, Earth mass is 5.9721986×10²⁴ kg – we Wolfram|Alpha the radius to get 8.87mm

It is not stated what would be the size of Earth, but if it goes below that horizon * wink, wink * then it is a black hole.

As per the trajectory, it would not be affected. The moon would stay in orbit. That is because the gravitational force doesn’t depend on density, just mass. The tidal forces across Earth are another thing, as Earth is smaller, it covers a smaller gradient of the gravitational effects of the moon (or the sun for that matter) – and at the same average distance from the moon – meaning that the difference of the effects on the Earth on the side near the moon and on the opposite side of Earth are minimal. Ergo, tidal forces are minimal too.

score 1 · Answer 2 · edited Apr 13 '17 at 12:40

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I believe in Ant-Man shrinking is accomplished by reducing the space between the subatomic particles, and the spaces between the atoms. The how this works goes unexplained (and I don't believe any theory grounded in physics can begin to explain this), and as I can offer nothing there, I'll brush over it.

Ignoring most of the issues this causes, I'll focus a quick discussion around one topic Orejano brought up, specifically gravity. Earth would maintain its mass, but would now be smaller than the eye can see. Even if we dial it back to being roughly 1 meter cubed, we get a density of 5.972 × 10^24 kg per cubic meter.

We can take a trip over to Physics Stack Exchange to determine the density of a black hole. The answer? Seems to be (at the heavy end) 6 × 10^18 kg per cubic meter.

Meaning even if we scale Earth to one meter cubed and not microscopic we're denser than a black hole.

Not a pretty outcome for the citizens of Earth.

edited Apr 13 '17 at 12:40

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answered Sep 22 '16 at 22:02

Ranger

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Being denser than a black hole shouldn't be a problem. The gravity would still be the same. If the force that is packing atoms tighter is all between adjacent atoms, it wouldn't increase the pull. – SRM Sep 23 '16 at 00:17
@SRM There's a pretty big difference in behavior between you and a blackhole with your mass. Light that reaches the blackhole-with-your-mass never leaves it, while light that reaches you may reflect off so we can see you. – Cort Ammon Sep 23 '16 at 00:35
Something wrong with your figures, as I recall that a black hole with the mass of the Earth would be about the size of a marble. – JDługosz Sep 23 '16 at 01:32
My point was this: gravity is the ONLY force that warps spacetime so far as I know... electromagnetic-nuclear forces do not. To make a marble size black hole in real physics, you slam together a massive amount of matter, the core of which becomes a microscopic black hole that builds as it absorbs matter. It starts because there's a gravity asymptote to seed it. Here, no such gravity pressure ever existed. It's simply that the atoms are closer without the commensurate warping of spacetime because a non-gravity force is involved. – SRM Sep 23 '16 at 04:40

Kevin · Answer 3 · 2016-09-23T02:52:56.850

If we didn't start collapsing immediately, I'd worry about...

the effects the shrinking had on earth's rotational velocity.
Changes in air density choking us to death
Freezing to death since earth has less area and will receive a fraction of energy it did before.
Packing all that fissile material into the area of a dime. I bet it'd all go off and we''ll likely get vaporized before freezing to death. Antman's tech couldn't affect the energy released and the energy per square meter would be insane.

Like others have said, mass is the same. We'd just be much denser and that may not kill us on its own.

What would happen if we shrink earth?

3 Answers3