This was examined in detail by the Straight Dope website a few years ago. http://www.straightdope.com/classics/a1_155 The net force is nil, of course, but if a billion people (not necessarily Chinese) all jumped off chairs at once they would only liberate the equivalent of 500 tonnes of TNT; a lot of energy, but not enough to create a significant earthquake.
Absolutely. Perhaps if everyone jumped with microsecond precision we could arrange for the force to be focused onto a single spot; it might be sufficient to demolish a building or two, but there are easier ways of achieving this.
Lets get the family car into it, brakes and tyres are great ways of converting some kinetic energy into heat, as with compression that was pointed out earlier. The key is converting kinetic energy into some other form. We can move the Earth but we will heat it up as well. Then there’s the natural resonance of the earth. If we could all jump in tune to these resonance frequencies we could have quite an impact.. An army marching in column is ordered to break step when crossing bridges. This is because if the bridges resonance frequency matches that of the step then the bridge may come down. Try it in a pool. Move up and down in time with the longest wave cycle you can find. In no time you will start to get good size standing waves.. (Works best in pools with even depth) If we all had a GPS device connected to a central server, which monitored low frequency (1Hz to 0.01Hz) seismic waves around the world, we could all be instructed to do a variety of actions to add energy to the oscillations. I wonder how long we would have to do this before the authorities step in.
So instead of world jump day, you are proposing Mexican Global Wave day. I like it. Please Register or Log in to view the hidden image!
Tesla did a lot of experiments with natural harmonics and electricity. Crazy old man. Tanks driving through towns and the like back in WWI and WWII would rumble houses into ruins and destroy the roads.
And men marching in one rhytm over a weak bridge would collapse the bridge. But it is another matter.
We should try getting the Chinese gov't to do this, lol. It can probably try to test this hypothesis since it is twice well over the population requirement.
so basically, from all you say here, there is no actually certain of what can or cannot happen... I mean, it is doubtfull that the orbit changes, yet, the effects of such mass in motion are a bit unpredictable... I guess we'll just have to wait and see
It is sad that man has come to nonsensical ideas like this to solve problems, then again, when hasn't he?
