# Pitching a baseball at 0.9c?

1. Jul 10, 2012

I came across this from xkcd today. The question seems interesting, but I was wondering if this expplanation quite covers this or are there other possibilities? (Also, is something wrong with this explanation?)

Basically they're dealing with a baseball pitched at relativistic speeds.

http://what-if.xkcd.com/1/

2. Jul 10, 2012

### BruceW

haha, yeah, something like that would probably happen. The ball would definitely get destroyed. Particle accelerators must be vacuum for this reason - if there was air in there, then the particles would collide with them. So if there was a ball going at this speed, then all the particles in the ball would collide with the air particles, giving off ridiculous amounts of energy.

3. Jul 10, 2012

@BruceW - An open air particle accelerator--my thoughts exactly!
So, basically, it's 150g of particles colliding with air molecules, so wouldn't the collision (for now let's assume there's no batter for a good distance) cause the entire ball to disintegrate resulting in the generation of energy we can't quite handle?
Or will it be within comparatively safe limits?

4. Jul 10, 2012

### BruceW

at 0.9c, the kinetic energy is at a similar level to the rest mass energy. And from what you know about E=mc^2, this is going to be a huge amount of energy since we have a tenth of a kilogram of mass to play with.

Edit: So, specifically, the energy output of the explosion will be of the order of c^2 times by 1/10 kilogram

Last edited: Jul 10, 2012