Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Changing Earth Orbit July 06! Is this for real?

  1. Jul 7, 2005 #1

    Crumbles

    User Avatar

    This site has a whole theory about changing the orbit of the earth by having 600 million people jumping at the same time.

    I am very skeptical about this. I mean it sounds like the violation of the conservation of energy/momentum if you can change the earth's orbit without any mass ejection or a collision of some asteroid with the earth.

    Can someone try to explain how this can be possible?
     
    Crumbles, Jul 7, 2005
  2. jcsd
    Phys.org - latest science and technology news stories on Phys.org
  3. Jul 7, 2005 #2

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    brewnog, Jul 7, 2005
  4. Jul 7, 2005 #3

    pallidin

    User Avatar

    Well, there WOULD be a mass ejection: the 600,000,000 people.
    The problem is that this ejection returns.

    Consider this scenario... 300 passengers on a 747(which is going about smoothly) suddenly decide to stand up and jump up in concert. If done properly, a collective force will be exerted on the 747 pressing it down. Then, just afterwards, the 747 experiences a lack of weight equal to the 300 passengers, so the 747 rises. Then the 300 passengers hit the floor and the 747 experiences a sudden weight gain and thus moves down.
    On average, there is no net effect.
    However, perturbations of the craft during this time most certainly occur.
     
    pallidin, Jul 7, 2005
  5. Jul 7, 2005 #4

    Crumbles

    User Avatar

    Ok so basically if they gather enough people with no brains out there and they actually jump, it wouldn't help the earth's orbit at all but just result in some stupid earthquake! :surprised
     
    Crumbles, Jul 7, 2005
  6. Jul 7, 2005 #5

    russ_watters

    User Avatar

    Staff: Mentor

    Well, lets calculate the energy involved real quick: Lets say the average of these jumpers is a svelte high-jumper who has a mass of 50kg and jumps 1m (yeah, I'm lazy). 600 million times 50 times 1 is 30 billion (giga) joules or 0.03 TJ. According to http://www.geop.itu.edu.tr/~onur/seis/eq_energy/ [Broken] site, thats half the energy of a 4.0 magnitude earthquake and an insignificant fraction of the energy of a nuclear bomb. So it'd be detectable, but you probably wouldn't feel it.

    But there's a catch: earthquakes are localized. They happen in a pretty small area and the energy travels outward as a wave. So the energy of those 600 million jumpers would need to be concentrated either by having them all stand on the same football-field sized area or jump in a precise sequence to cause the waves to constructively interfere.
     
    Last edited by a moderator: May 2, 2017
    russ_watters, Jul 7, 2005
  7. Jul 7, 2005 #6

    Crumbles

    User Avatar

    Ha ha! I like it! Can't wait for the 20th July of next year to watch a bunch of blisfully ignorant fools jumping thinking it's gonna do something!! :rofl:
     
    Crumbles, Jul 7, 2005
  8. Jul 7, 2005 #7

    yourdadonapogostick

    User Avatar

    even if that small number of peole could cause such a force by jumping, it wouldn't do any good....the earth has gravity, so they will come back and counteract the force they made by jumping.
     
    yourdadonapogostick, Jul 7, 2005
  9. Jul 8, 2005 #8

    Deek

    User Avatar

    What is the purpose of altering the Earth's orbit?
     
    Deek, Jul 8, 2005
  10. Jul 8, 2005 #9

    Crumbles

    User Avatar

    If we can alter the earth's orbit to be slightly further from the sun, it could solve climate issues such as global warming etc..
     
    Crumbles, Jul 8, 2005
  11. Jul 8, 2005 #10

    Pengwuino

    User Avatar
    Gold Member

    I thought we already got this every november 2nd since the 60's :rofl: :rofl:
     
    Pengwuino, Jul 8, 2005
  12. Jul 8, 2005 #11

    Deek

    User Avatar

    Or we could investigate alleviations to pollution. Which one seems more sensible to you?
     
    Deek, Jul 8, 2005
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook