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The folks behind World Jump Day are

The folks behind World Jump Day are trying to shift the earth into a new orbit. Dunno if the science behind this is kosher, but the idea is that if 600 million people all jump at the same time, their collective landing will shift the earth into a different orbit and solve our warming problem.

Reader comments

HensleyFeb 27, 2005 at 10:02AM

I thikn perhaps you intended to type "shift the earth." The existing title is quite intruiging!

Stacey KnowlesFeb 27, 2005 at 10:06AM

600 million people doing the other thing just might work... I just hpe they don't, that's all.

sarahFeb 27, 2005 at 10:12AM

Fantastic headline. Don't you dare change it.

jkottkeFeb 27, 2005 at 10:16AM

Shift! It's shift! (Note to latecomers: the headline read "trying to shit the earth into a new orbit"...perhaps a more interesting proposition, but untrue.)

Anyway, any physicists out there know if this orbit shifting is possible?

ArminFeb 27, 2005 at 10:25AM

I'm not a physicist, but I still think this doesn't make sense:

As far as I can tell from a quick glance at the site it doesn't matter where on earth you are to participate. Therefore someone jumping in, say, Australia, would cancel out someone jumping in Canada (not sure if they are exactly opposite, but you get the point).

And I remember reading something about all Chinese people jumping at the same would shunt the earth out of its current orbit, which was swiftly disproved. I think.

ArminFeb 27, 2005 at 10:40AM

Me again, here's a link about the Jumping Chinese.

BobFeb 27, 2005 at 10:51AM

Weren't you a physics major, Jason? Did something happen to Newton's Laws that I don't know about?

JamesFeb 27, 2005 at 11:00AM

I am a physicist (well, an undergraduate one at least) and I'm fairly certain that this will make no difference. They will impart some momentum on the Earth when they land (assuming they don't all cancel each other out), but they will also remove the same amount of momentum from the Earth when they jump, so the jumping and landing together have no net effect. Also their claims about climate change are pretty sketchy; even if this did change the Earth's orbit, given the number of people they need I doubt it could be done with very much precision, so there's no telling what the new orbit would look like.

Having said that, the fact that the recent Asian tsunami shifted the Earth's axis of rotation would seem to contradict my argument, so maybe there's something in this after all...

MartinFeb 27, 2005 at 11:14AM

My guess would be that the mass of all the people in the world is much, much smaller than people think, relative to the mass of the earth. When you thump your finger against your leg, you're talking about something with a mass of, what, an ounce? (your finger), versus something with a mass of a couple hundred pounds (your body). So you can feel that. My guess is that the combined mass of humanity doesn't come close to the mass of the finger (in this example). And even a finger, by itself, can't really move anything the size of a body or a leg in one blow anyway.

JoeFeb 27, 2005 at 11:19AM

Yes but changing a rotaion and an orbit are so much diffrent. To somehow "move the earth" is just silly in my head. I

Also people jump at diffrent heights, One person may jump higher than the other and therefore hit the ground at a diffrent time than a person jumping lower than them.

Don't think it will ever work.

ramananFeb 27, 2005 at 11:34AM

Sorry, but isn't this like trying to move a car by pushing against it from the inside? It's been many years since I've taken a physics course, but I don't think this works.

Joe (number 2)Feb 27, 2005 at 11:36AM

If 600 million people jumped off a bridge, would you?

AfroozFeb 27, 2005 at 11:40AM

Hi guys,

I'm a big fan of the site, and I happen to be a science nut. This is a classical example of people not knowing physics. So earth weighs roughly 6 times 10 to the 24 kilograms. If we assume that everyone on earth weighs 220lbs (or 100kg) and they magically turn into ONE MASS, that mass will make barely make any difference at all! The mass will still be 13 powers of ten less massive than the earth. I did the whole calculation once, an the earth shifts a distance smaller than an atom I believe!

By the way, I'm developing a site with all this sort of stuff called Mad Physics Dot Com. It should be done in a week, I hope you guys come. I will post this proof in more detail!


WilliamFeb 27, 2005 at 11:45AM

To reiterate what others have said, just look at the effect of the recent earthquake that caused the tsunami. An earthquake of this magnitude only shifted the earth's orbit a fraction of a degree. Now, think about it. How many tsunamis will 600 million people cause?

And who knows which way the jumping will shift the earth's orbit? They might even shift us into an even worse position for global warming.

AfroozFeb 27, 2005 at 11:46AM

By the way. Those who are not big math nerds. If everyone jumped (and they weighed 220lbs each) the earth would still weigh:

10,000,000,000,000 times more than them.

I just thought I'd write out all of the zeros to emphasize the point that World Jump Day wasted their domain registration money!

bingFeb 27, 2005 at 12:08PM

It wasn't the tsunami that changed the earth's rotation, it was the earthquake. And it wasn't the earthquake's shaking, it was the slipping of one plate over the other.

The Earth's circumfrence pulled in by the merest of degrees, and thus we're rotating that much faster, centripodal force, conservation of momentum etc...

yafujifideFeb 27, 2005 at 12:13PM

The only reason the tsunami affected the Earth's orbit was because it permanently altered the shape of the Earth. As others have said, when people jump, their landing cancels out any shift in orbit.

Now if they were to launch millions of tons of matter into space that never came back down, that would shift our orbit.

jkottkeFeb 27, 2005 at 12:44PM

Weren't you a physics major, Jason?

I was, but it was a long time ago and the specifics have long since left my brain. And I guess this also ties into my earlier post about plausible lies and false truths.

Dan BrunoFeb 27, 2005 at 2:30PM

I remember my high school physics teacher disproving this sort of thing, using conservation of momentum.

Still, I gotta give them credit for having over 60 million people registered to do this...

daveFeb 27, 2005 at 3:24PM

If they were really serious, they'd sell us large rocks to drop from 2nd storey windows.

DanielFeb 27, 2005 at 4:35PM

Didn't they do this on Futurama with the robots "venting" at the same time? Just this time it's with people and not as funny?

ZacFeb 27, 2005 at 5:16PM

Maybe if all 6.5 billion of us got together on a fragile tectonic boundary. Even if the calculations show it won't work, who here is in support of shelving the Mars shot for an international collaboration that gives us all a trip to Parkfield, Istanbul, or Queenstown?

AfroozFeb 27, 2005 at 5:44PM

Hey guys,

My rebuttal is online! World Jump Day is Wrong!. Jason, if you could it would be great if you could post the link as a follow-up or something. That is, if you approve.

*Humble Bow*

Soeren DalsgaardFeb 27, 2005 at 7:28PM

Anybody taking world jump day seriously is being.....had. It's a joke, just like

xinaFeb 27, 2005 at 8:00PM

world jump day is for the birds. everyone knows the earth is flat!

Carl CaputoFeb 28, 2005 at 2:39AM

Um, I’m kinda surprised nobody’s mentioned that Cecil Adams demolished this hooey-ridden notion in 1984, in a true classic among his responses.

As you can imagine, I possess phenomenal scholarly resources. I have converted the spare bedroom in my house into a research library containing 16 million volumes, which are dusted twice a day by a team of robed acolytes holding candles. I have instant access via my Apple 380S GT to all the world’s data banks. Why, right here on my writing table next to the box of spare quills I have a dog-eared copy of 16,000 Unbelievably Complicated Physics Experiments for the Home and Garden, With Answers, which has helped me out of many a jam.

But despite this wealth of scientific knowledge, the Teeming Millions routinely write in with questions that not one sane person has ever asked in 6,000 years of recorded history. As a result, my usual sources of information are useless.

And on to the demolition.

electricincaFeb 28, 2005 at 8:32AM

The people behind this World Jump Day appear to be a German art/media group called Vene Hammerschlag or at least it is hosted on their server.

They describe themselves thus Vene Hammerschlag ist eine Gruppe von interdisziplinar arbeitenden Kunstlern und Mediengestaltern, die Raume schafft fur eigene Werke und Werke anderer Kunstler. Die Verbindung der untershiedlichen Disziplinen mit herkommlichen Party-Elementen an immer verschiedenen orten fuhrt zu einer neuen und zeitgemassen Form von Ausstellung.

Who says Germans have no sense of humour?

LeoFeb 28, 2005 at 3:49PM

Howdy folks. As someone who just recently gave up on a major in Applied Physics in favor of Computer Science, I still remember a thing or two.

So, translational motion: Whenever you jump, we can call you and everything that's not you two pieces of mass in a system. Conservation of momentum, which is always applicable (as opposed to conversation of energy, for example) says that the center of mass of you and the rest of the Earth stays put unless there's some force from outer space. As you jump up, the Earth will move away from you distance proportional to the ratio of your masses. (rough estimate: a trillionth of a trillionth of a billionth of a meter.) You apply this same rule to everyone on Earth, and it remains self-consistent. As people fall back to the ground from their respective jumps, the reverse process happens. No net effect.

Rotational motion is a LOT tricker. If you had everyone on one side of the Earth lay down, and everyone on the other side stand up, then we could shift the axis of rotation of the Earth and make summers warmer and winters colder or something stupid like that. But again, only by the slightest of margins.

Hope that helps.

inspoeticaFeb 28, 2005 at 4:28PM

Another link to Jumping Chinese.

AfroozFeb 28, 2005 at 7:38PM

"Rotational motion is a LOT tricker. If you had everyone on one side of the Earth lay down, and everyone on the other side stand up, then we could shift the axis of rotation of the Earth and make summers warmer and winters colder or something stupid like that."

Not Quite. Remember your powers of ten guys!

RustjiveMar 03, 2005 at 10:14AM

Pretty sure the entire thing is just an elaborate hoax. A search for "Niesward" on Google Scholar turns up one Steve Niesward, from New Jersey. It seems unlikely that someone becomes a professor without publishing, but maybe he's an adjunct or something. Another search for "Institut fur Gravitationsphysik" shows that there's indeed one - but not in Munich. A search for Munich universities shows that there is no "Institut fur Gravitationsphysik" in Munich.

An easy way to get email addresses for spam, or perhaps a complex art project.

lerxtMar 04, 2005 at 10:53AM

It is very clear that the earths orbit can not be shifted (because of momentum conservation laws), but the axis or the rotation speed can de changed from the earth (there is no physic law against that).

I have a much better idea, to change the world jump day into the world running day. That day everyone should run east. That should make the earth spin slower, and have longer days.

The idea is to alternate running to the east on weekends, and run west on week days. Imagine that! work less and rest longer!

McKay SalisburyMar 04, 2005 at 3:58PM


Problems with Angular stuff.

If everyone lay down, or stood up as was proposed, then there would be a fractional change,

but that's assuming that all the changes are permanent. Those people lying down, had to have been lying down in the first place. The act of lying down will counteract all the benefits they will be getting when they stand up. Consequently, those people who lye down, will have to eventually stand up (unless they decide to remain there for an eternity, like if somone shot them (remember to calculate that momentum into the equation too).

Runnign to the east and west will have similar consequences. Remember that if I run 20 miles west every night, I'll have to run 20 miles east in the morning so I can get back to work. (I'd be driving my car anyway, same benefits except more mass = more delta angular momentum) Some sort of work shifting could occur. By the end of the week, I'd be working 100 miles further west than I did on monday, so I'd be taking someone elses place. The problem with this is that there's a lot of people in california who don't exactly have anywhere to go (you know the san andreas fault worries? this will happen every week).


This thread is closed to new comments. Thanks to everyone who responded.