# Particle Accelerators effects on Earth

by azabak
Tags: accelerators, earth, effects, particle
 P: 32 Since particle accelerators need to be a cyclical structure in order to generate the collisions it has associated to it an angular momentum. Due the conservation of angular momentum we use the rotational kinetic energy of Earth itself to supply them. Take, for example, a particle accelerator that is operating aligned with the axis of rotation of the Earth. If it was able to generate angular momentum in the same direction of the Earth's rotation could it, if supplied with enough energy, stop the rotation of the Earth?
P: 15,294
 Quote by azabak Since particle accelerators need to be a cyclical structure in order to generate the collisions it has associated to it an angular momentum. Due the conservation of angular momentum we use the rotational kinetic energy of Earth itself to supply them. Take, for example, a particle accelerator that is operating aligned with the axis of rotation of the Earth. If it was able to generate angular momentum in the same direction of the Earth's rotation could it, if supplied with enough energy, stop the rotation of the Earth?
Not sure you appreciate the scale here. Particle accelerators move very tiny amounts of atoms. Microscopic amounts.

True, when accelerated to relativistic velocities, they can pack quite a punch. In an article about the LHC, they suggested that stepping in front of a beam of particles would be like getting hit by a truck. That's a lot of momentum for a few tiny particles - but it's about a thousand billion billion billion times smaller (1021) than the Earth's momentum.
P: 2,193
 Quote by azabak Since particle accelerators need to be a cyclical structure in order to generate the collisions it has associated to it an angular momentum. Due the conservation of angular momentum we use the rotational kinetic energy of Earth itself to supply them. Take, for example, a particle accelerator that is operating aligned with the axis of rotation of the Earth. If it was able to generate angular momentum in the same direction of the Earth's rotation could it, if supplied with enough energy, stop the rotation of the Earth?
First off, accelerators don't need to be circular, they can be linear as well.

Secondly,
http://xkcd.com/162/

Mentor
P: 13,648

## Particle Accelerators effects on Earth

 Quote by azabak Since particle accelerators need to be a cyclical structure in order to generate the collisions it has associated to it an angular momentum. Due the conservation of angular momentum we use the rotational kinetic energy of Earth itself to supply them.
First off, as DaveC already noted, the angular momentum here is tiny.

More important, due to the conservation of angular momentum, almost all of that angular momentum is eventually transferred back to the Earth. There is some lost angular momentum in the form of neutrinos, but that is tiny, tiny, tiny.

You're tilting at the wrong windmill. If you want a windmill to tilt against, think about us evil aerospace engineers. Every one of the satellites sent up to geosynchronous orbit, and every one of the probes sent to other planets, is launched to the east precisely because this king of launch lets us steal a tiny bit of the Earth's rotational angular momentum, thereby making the launch a bit cheaper.
 P: 32 The energy we use comes partly from the Earth and partly from the Sun. Sending things into space, creating faster vehicles, accelerating particles, all this uses our available energy. Even it being a huge discrepancy still exist. We didn't expected to have climate problems some thousand years ago, but now we know that humans can indeed affect significantly the cosmic environment. Imagine if in the next millennium we have problems like "putting Earth back on its rotation axis".
 Mentor P: 14,665 Like others, I suggest you work the numbers out.
 P: 126 The round-a-bouts on the highways have a greater effect than particle accelerators.
P: 261
 Quote by alexg The round-a-bouts on the highways have a greater effect than particle accelerators.
Aw, horror! We need to make every second one to go round the other way to compensate!
 Mentor P: 14,665 This is why some countries have to drive on the wrong side.
P: 1,285
 Quote by DaveC426913 Not sure you appreciate the scale here. Particle accelerators move very tiny amounts of atoms. Microscopic amounts. True, when accelerated to relativistic velocities, they can pack quite a punch. In an article about the LHC, they suggested that stepping in front of a beam of particles would be like getting hit by a truck. That's a lot of momentum for a few tiny particles - but it's about a thousand billion billion billion times smaller (1021) than the Earth's momentum.
Isn't that the energy of being hit by a truck?

If I compute the momentum with p = E/c (quite accurate for particles with a kinetic energy so much larger than the rest-energy), I get:

p = 7.7 Tev * (number of protons) / 3*10^8 m/s = 7.7*10^12 * 1.6*10^(-19) * 5 * 10^14 / (3 * 10^8) = 1.9 kg m s^(-1).

This is more like the momentum of a pigeon.

data from here:
http://accelconf.web.cern.ch/accelco...c1992_1545.pdf

Of course the large hadron collider uses two beams that go in opposite directions, so the net effect is 0.

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