From the gravitation equation it is clear the earth gets pulled but we fall due to negligible mass. But, if each and every person on the earth takes a jet-pack and jumps to a height equivalent to 20 to 30 meters at the same instant of time, will the earth have any change in its motion? If yes then what could be the outcomes?

  • $\begingroup$ This is more of a speculative physics question than anything to do with space exploration as currently phrased. $\endgroup$ – called2voyage Apr 26 '16 at 15:25
  • 3
    $\begingroup$ It's not exactly a jetpack, but the result would be the same: what-if.xkcd.com/8 $\endgroup$ – Antzi Apr 26 '16 at 16:35

Unlikely any meaningful effect. Some napkin math...

Weight of average human: $62 kg$

Population Estimate: $7.4 \times 10^9$

Mass of combined population: $4.5 \times 10^{11} kg$.

The mass of Earth is estimated $5.972 \times 10^{24} kg$.

That's a huge order of magnitude in difference, and as such any gravity effects should be barely noticeable.

  • $\begingroup$ Phrased another way, the human population biomass on Earth ($10^{11}$ kg) is to the Earth ($10^{24}$ kg) roughly as a regular-sized bar of chocolate ($0.1 = 10^{-1}$ kg) is to the human population biomass on Earth ($10^{11}$ kg). $\endgroup$ – a CVn Aug 26 '16 at 14:36
  • $\begingroup$ I'm pretty sure if we rolled every human into a ball and collided it with the earth at 2000km/s we'd basically be able to take out a city, maybe a few cities nothing more. $\endgroup$ – Magic Octopus Urn Mar 28 '19 at 13:17

Not the answer you're looking for? Browse other questions tagged or ask your own question.