Misconceptions often get carried away. There is a new website called World Jump Day. It asks for people to jump at certain times on July 20, 2006. They claim that if it happens, the world will shift out of its orbit and there will be no more global warming. In fact their website says quite plainly that “Scientific research has proven that this change in planetary position [that's caused by jumping] would very likely stop global warming, extend daytime hours and create a more homogenous climate.” My first complaint in this claim is that he says research has proven it is silly to make such claims because science is definitely not the end all be all.
The goal of science—particularly physics—is to further our understanding of the world by looking at thimgs differently and thereby challenging convention. Einstein became what he was by challenging the foundation of his field. Therefore, if we are to assume that because some unnamed man with uncited research claims that bouncing will change our ecosystem, you have to take it with an enormous grain of salt. Anyway, to show you how claims should be made, I am here to refute the whole argument with numbers and basic physics. By the way, I shouldn't be making this agrument to begin with! That is because if the people who are jumping are from earth, then the forces of them leaving and landing would cancel each other out, and their net force would be zero (Newton's 3rd law). So, for the sake of it, let's invent new people!
Let us assume that the average (mean) mass of earth’s 6 billion inhabitants is 100kg (a gross overstatement, but the numbers are better). That would make their collective mass 6x1011kg.
Now let’s assume that all these people have fused into one sphere of that mass. If we assume that acceleration due to gravity on earth is 10ms-2 then if the mass jumps one and one fourth meters it will land with a velocity of 5ms-1.
The kinetic energy produced by the jump would equal to:
75x1011 Joules or 7.5 TJ (tera-joules)
7.5 TJ is approximately 2% of the energy released by one Megaton of TNT, which is also the size of a modern H-Bomb.
Basically the United States has tested similar bombs, but the earth’s remained fixed.
That may be because the earth has a mass of 6x1024 which means that the mass I spoke of was:
10,000,000,000,000 times smaller, which means the displacement caused by everyone jumping would shift the earth a tiny fraction of the radius of a hydrogen atom.
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