# Can we move the earth?

1. Dec 25, 2004

### Gughanath

This might be a weird question, but hey, thats what physics is all about!
Say everyone in the whole world jumped as high as they could at the same time, would the earth move??

2. Dec 25, 2004

### rayjohn01

A little

Assuming the people who did the jumping were more or less in one hemisphere and NOT equally distributed , I suppose the answer is yes but it would certainly not be much and it is not permanent.
Imagine someone standing on the earth on a plate under which is a powerful spring. The spring is triggered and the person accellerates upwards -- the earth also accellerates downwards ( in the sense of opposite). But due to the mass of the earth it moves a lot less -- At some point if the person does not reach escape velocity , then the very same force which the spring overcame will bring them together again - but when he hits the earth all the energy of the spring will be dissipated as heat , in which case everything returns to normal except the original stored energy in the spring has gone in a slight gain in local temperature .
At least thats my Holiday theory.
Ray.

3. Dec 26, 2004

### Tom Mattson

Staff Emeritus
The Earth's motion would indeed be affected because the Earth's rotational inertria would change. But you don't even have to have a situation as elaborate as all that. It's also a fact that you alter the motion of the Earth simply by walking! When you walk a frictional force develops between the Earth and the bottom of your feet. The force exerted on you by the Earth propels you forward, and the equal and opposite force exerted on the Earth by your foot pushes the Earth backwards (it also exerts a torque about the center, to complicate matters even further).

4. Dec 27, 2004

### rcgldr

Tidal actions from the ocean are slowing down the earths rotation.

The recent 9.0 earthquake near Thailand altered the earth's orbit by a tiny amount (shift in the center of gravity of the earth).

5. Jan 2, 2005

### Problem+Solve=Reason

Like Jeff stated; it is possible to move the earth a tiny bit by simple movments, but the earth will gradually move back to the original orbit.

This is true, unless we where to be hit so hard that the earth actually detacthed from the orbit. Isn't it also true that a butterfly landing on a tree moves all particles around it and causes a domino effect therefor moving all of the matter in the universe?

Last edited: Jan 2, 2005
6. Jan 2, 2005

### lawtonfogle

I like the thought. The only thing is will the butterfly have an affect on anything that will change the course of the univeres' destiny, or was this the destiny predetermined and the butterfly could not have not land on the tree???

And the earth can be moved but moving it either way will do one thing, just by two different paths, kill us.

path A We go on a path straight into the sun (well the path will still orbit the sun)

path B We go on a path and freeze as we leave the only orbit around the sun that it is hot but not to much as we travel away from the sun

So why would it matter if we could or couldn't. Let us not try to find out. OK!