World
What If Everyone Jumped?
Short answer: the planet would barely notice. Eight billion people jumping 30 cm would move Earth by much less than the width of an atom, and it moves back as soon as everyone lands.
If everyone on Earth jumped at once, would the planet notice?
Conservation of momentum does not care about feelings. If eight billion people push down on the ground together, Earth is pushed the other way by the same impulse. Earth's mass is about 6 × 10²⁴ kilograms, so the recoil speed is not a rounding error in a poetic sense — it is a rounding error in a literal one, something like 10⁻¹³ metres per second. While everyone is in the air, the planet has that tiny delta-v. When they land, they hand the momentum back. Net displacement of Earth's orbit is not a thing this experiment will claim. The interesting number is how small a planet makes a crowd.
Written and checked by Aivora Digital · Last updated:
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About 8 billion is a current world population ballpark.
Your result
2.01 × 10^−13
Earth's peak recoil speed (m/s)
while everyone is airborne
- Takeoff speed
- 2.43 m/s
- Momentum of the crowd
- 1.20 × 10^12 kg m/s
- Earth recoil Δv
- 2.01 × 10^−13 m/s
- Kinetic energy of the jumps
- 1.46 × 10^12 J
- After they land
- net Δv ~ 0
- Earth mass in the model
- 5.97 × 10^24 kg
What does that mean?
While 8,000,000,000 people of 62 kg are in the air after a 0.3 m hop, Earth recoils at 2.01 × 10^−13 m/s. That is not a typo in the exponent. Hang time is about 0.49 s; then they land and the impulse reverses. Net change in Earth's orbit: about zero. The people were already part of the planet. A jump is a brief internal rearrangement, not a rocket.
At a glance
- Crowd mass4.96 × 10^11 kg
- Earth mass5.97 × 10^24 kg
Compare
| Airborne | 2.01 × 10^−13 m/s recoil | |
|---|---|---|
| Back on the ground | ~0 net | momentum returned |
| Earth's orbit | not shifted by a hop |
Compare scenarios
A jump is a brief loan of momentum
Takeoff speed for a hop of height h is sqrt(2gh). Multiply by the number of people and their mass and you have a momentum. Divide by Earth's mass and you have a recoil. The formula is the same one that makes a rowing boat nudge backward when you step onto the dock, written at planetary scale. No, the planet does not 'shift in its orbit' in any lasting way. Orbits care about the centre of mass of Earth-plus-people, which barely moved because the people were already standing on Earth.
Landing closes the books
While the crowd is airborne, Earth has a whisper of opposite velocity. Contact on landing applies the opposite impulse (plus a bit of heat and sound). After everyone is standing again, the Earth–crowd system has the same total momentum it started with, ignoring the millimetre of extra height they no longer have. If you want a lasting change in Earth's motion, you need to throw mass into space or rearrange it permanently. A jump is neither.
Energy is a crowd, still not a quake
Kinetic energy at takeoff is ½ N m v². For eight billion people that can look like a large joule count because there are many of them, not because any one patch of crust was loaded like a bomb. The energy is spread across every inhabited place at once. This page will show the joules and refuse to translate them into a fake earthquake magnitude. Magnitude is a local seismic measurement. A coordinated hop is not one.
Worked example: 8 billion people, one jump
- Each person (62 kg) jumps 30 cm, which needs a take-off speed of about 2.4 m/s and keeps them in the air for about half a second.
- Total momentum: 8 billion × 62 kg × 2.43 m/s ≈ 1.2 trillion kg·m/s.
- Earth’s mass is about 5.97 × 10²⁴ kg, so its recoil speed is 1.2 × 10¹² ÷ 5.97 × 10²⁴ ≈ 0.0000000000002 m/s (2 × 10⁻¹³ m/s).
- In half a second that moves the Earth about a tenth of a trillionth of a metre, far smaller than an atom. Then everyone lands and the Earth moves back.
- Total energy at take-off: about 1.5 trillion joules, roughly the energy of 350 tonnes of TNT, but spread across every inhabited place at once.
If everyone on Earth jumped together, the planet would move by much less than the width of an atom and return as soon as they landed.
What people get wrong
- “It would knock the Earth out of its orbit.”
- The people start and finish on the Earth, so the Earth-plus-people system never changes its motion through space. The orbit is unaffected.
- “It would set off an earthquake or tsunami.”
- The landing energy would be spread across billions of separate spots, each one about as forceful as a person jumping off a step. Earthquakes release energy from one fault in one place.
- “Everyone could jump at the same moment.”
- People are spread across every time zone, so it would be the middle of the night for billions of them. Even a perfectly timed jump would change nothing measurable.
Common questions
What would happen if everyone on Earth jumped at the same time?
Almost nothing. The Earth would recoil at about 2 × 10⁻¹³ metres per second for the half-second everyone was airborne, then return when they landed. The sound and the crowds would be the only noticeable effects.
How many people are there on Earth?
The United Nations estimated 8.2 billion people in 2024. This page uses 8 billion as a round default; you can change it with the slider.
How we calculated this
Takeoff speed is sqrt(2 g h) with g = 9.80665 m/s². Earth’s recoil = the total momentum of everyone jumping (people × mass × take-off speed) divided by Earth's mass from the NASA fact sheet. Delta-v is that ratio. Energy is ½ N m v². After landing, net delta-v is treated as zero. People are a number slider, not a geographic map, so there is no crustal loading model and no seismic magnitude.
Assumptions and limitations
This is a simplified estimate. Actual results depend on factors the model does not include.
This is a simplified thought experiment. It uses transparent assumptions so you can see what changes — it is not a full physical simulation of the real world.
- Everyone jumps at the same instant and the same height.
- Takeoff is vertical in the local up direction; Earth is a rigid body of mass M⊕.
- Air resistance and the fact that people are not uniformly spread are ignored.
- Landing returns the momentum; net orbital change is ~0.
- No earthquake scaling is attempted.
Sources
- NASA Earth fact sheet
Mass, radius, rotation period and orbital speed used as the baseline Earth.
- NIST CODATA — standard acceleration of gravity
gn = 9.80665 m/s², the conventional standard gravity (also ISO 80000-3).
- United Nations — World Population Prospects 2024
Estimates the world population at 8.2 billion in 2024.
Go further
Related experiments that pick up where this one leaves off.
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