http://www.worldjumpday.org/

supposing every human jumped and landed at the same time on a very small area on one side of the earth, would it affect anything at all?

I'd like some energy calculations by some more calculus-oriented of you.

edit: moreover, is professor Hans Niesward truly existing professor and is there such thing as department of Gravitationsphysik at Munchen, Germany?

I just thought it would be fun to debunk a completely harmless "theory"

This was discussed recently here.

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thanks 8)

How silly we are to think that our weight could do anything.

We would have to collectively leave Earth, and then slam into it as a human race meteor.

Jumping in the air does not decrease the mass of the Earth. Landing from a jump does not increase the mass of the Earth.

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If you jump of a chair on 31st dec at 23:59:59.6 and land after midnight you can then go around claiming that you jumped into the year or decade if you wait 5 years.

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Huh?

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If there are 5 billion people on Earth and the average weight is 150 lbs then there are 375 kilotons of people. If all of them jumped 100 miles into space and landed in the same place you would have about a third of the energy of the Hiroshima bomb or the equivalent of a small tactical nuke.

All you would get would be a few squashed ants.....

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You would also have a lot of people puree 8)

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No I meant de-orbit the entire population of the Earth. Send em round the Sun once in asbestos suits and slam them into the Earth at 14,000 miles/ Second.

Still wouldn't de-orbit the Earth but would make a hell of a hole.

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It might be better and less painful to use some other source of mass.

Perhaps one of those mountains in the Himalaya... 8-[

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I received an email about this. I'll do the energy calculation at some point...

... but it doesn't matter. Even if everyone on Earth weighed a thousand times what they do, and all jumped on the same patch of Earth, the orbit won't change.

Why not? Because the center of mass of the system won't change. It can't, unless people actually leave. When they jump up, the CoM will move up a tiny bit (probably the width of a proton's whisker), but it will go back to where it was when people land.

So this won't work at all.

Incidentally, an iron meteorite 100 meters across would weigh as much as about 25 million people, but the energy equivalent is far higher, of course. And since the meteorite comes from outer space, it does effectively change the CoM of the Earth. Yet no impact like that could possibly shift the Earth's orbit.

Anyway wouldn't a change in orbit just make it more or less elliptical or change the plane of the orbit? There would be no benefit visa vi globalwarming.....

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If you look at momentum there's a tiny scale difference of ~10^17 between the best humanity could do and Earth's linear momentum.[/url]

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A gnats fart in a tornado.....

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But what about angular momentum? If you got everyone to run east or west at several m/s, you'd change the rotation rate. When they stopped, of course, the speed would change back, but you'd get a step in the elapsed time.

The earth's rotational angular momentum is (assuming I did the math right) about 7e33 kgm^2/s. A billion 100 kg people moving at 1 m/s has an angular momentum of about 6.4e17 (being on the surface is a big advantage here), so the rotational rate slows by a part in 10^16. Not quite to the level that atomic clocks could see it.

Now, get everone to ride a bicycle or drive a car in the same direction, and we might be able to see something.

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Will this bring back 1999?

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No, not even if Superman does it

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My calculation give 375000 kilotons

I make it 340,000 kilotonnes!


but its close. 8-[

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It would have no significant effect. A simple illustration makes this clear:

Earth weighs 6,580,000,000,000,000,000,000 tons (6.58E21). Say about 6 billion people can jump. Their collective weight is about 450,000,000 tons, or 1/14,600,000,000,000th of the earth's weight.

A small flea jumping off a locomotive imparts thousands of times more momentum to the locomotive than all the people on earth would impart to the earth if they simultaneously jumped.

What if they kept jumping?


No, the real thing against this idea is that, gravity acts like an invisible elastic band that when the person jumps up he pushes the Earth away from him with the same momentum with which he then rises in the opposite direction. The Earth and the person then attract each other and are brought back to the "same" position, given that the earth will have moved in its orbit while the man was in the air. But their is eventually no effect, just as if an astronaut were just 1 meter away from the space shuttle with no attachment, there is absolutely nothing he could do to get back to the ship without some help, or a heavy spanner to act as "propellant", throwing it as fast as he could in the opposite direction in which he wanted to go.

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Once again... The net mass of the Earth would remain constant.
Your still standing on the Earth.

Like Popeye blowing into the sail of his sailboat to push it along.

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Even then, you would have to do it right.

There are two ways I can imagine where humans could, in principle, be used to significantly affect the earth's orbit:

(1) Build a "human gun" that fires people into space at a velocity arbitrarily close to the speed of light (.9999999999....), never to return. The energy source, gun design and managing the potentially damaging effects on the planet and the people being fired are left as an exercise to the reader.

(2) Remove all people from the earth at conventional velocity, then fire them at the earth at a speed arbitrarily close to light. The method to accelerate the people to this speed is left as an exercise to the reader.

While both methods could affect the earth's orbit, it is expected that the effect on both people and planet would be somewhat unpleasant.

I think Amnesty International would have something to say about this idea.....






8)

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