Hitting a 0.9c fastball...

[grayhawk]

What would happen if you tried to hit a baseball pitched at 90% the speed of light?

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

Follow up question: If it was fouled back, how well would the new Unequal CP work?

[Dannytheman]

What would happen if you tried to hit a baseball pitched at 90% the speed of light?

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

Follow up question: If it was fouled back, how well would the new Unequal CP work?

Yup, he gets first base, dead ball!! Dead batter, umpire and anyone else within a square mile. :agasp_:

[JHSump]

Ha! A graduate student of mine sent me this link yesterday! Pretty neat description.

And, yeah, this is really one situation where calling "Dead ball!" is warranted!

[johnnyg08]

I love this article. Great stuff!!

[carolinablue]

" Sounded like a strike".

[Jocko]

Ha! A graduate student of mine sent me this link yesterday! Pretty neat description.

And, yeah, this is really one situation where calling "Dead ball!" is warranted!

you're the prof, right? So an object traveling at the SOL inside the Earth's atmosphere creates fusion resulting in nuclear blast? According to the laws of physics, is this mathematically accurate?

[JHSump]

Ha! A graduate student of mine sent me this link yesterday! Pretty neat description.

And, yeah, this is really one situation where calling "Dead ball!" is warranted!

you're the prof, right? So an object traveling at the SOL inside the Earth's atmosphere creates fusion resulting in nuclear blast? According to the laws of physics, is this mathematically accurate?

Yeah, I'm the prof.

The description sounds pretty realistic, in terms of physics. Certainly, the nuclei in the atoms of the ball would have more than enough velocity to fuse with atoms in the air, releasing energy, just like in fusion reactions that take place in the Sun. And plenty of energy would be released.

How much energy? Well, a common thing for physicists to do is a "back of the envelope" calculation to get a rough result, just to see if an idea has any merit. Enrico Fermi was famous for doing such calculations, and, interestingly, was one of the founding fathers of nuclear energy (and bombs). I did two such rough calculations for this situation.

1) If every proton in the ball were to undergo a reaction with a proton in the air, and release the typical amount of energy released in a nuclear reaction, then the amount of energy released would be equivalent to about 3 kilotons of TNT. That's equivalent to a small nuclear weapon.

2) Even scarier, if all the kinetic energy in the ball's motion were converted to heat, it would be roughly equivalent to a 1 megaton TNT explosion --- a large thermonuclear explosion.

Without trying to sort through any other details, I suspect the actual result will be somewhere in between these results. Either way, its a big kaboom!

[Jocko]

Interesting. Would you think atmospheric pressure and humidity would affect the size and type of kaboom? I would envision greater humidity would due to the "heaviness" of the air from water molecules. If this happened on the coast with the AP, it seems the explosion wouldn't be as far reaching as it would in say Denver. No calculations made, just brainstorming.

[JHSump]

The atmospheric conditions would certainly affect the extent of the expansion of the fireball. It's exactly as you say: the density of the air is important. This effect was worked out back in the 1940s as part of understanding the nuclear tests. I've seen it applied to supernovae explosions (same idea, the density of interstellar gas affects the range and rate of expansion of the shock wave).

But, if you ask me about how large the effect would be, that's a detail a "back of the envelope" calculation would not so easily capture. So, I don't have that answer.

I think the website where the OP comes from will be posting such discussions weekly. I doubt they will be baseball related much of the time, but I think they want to address "everyday" things, and they welcome submitted questions. The site is http://what-if.xkcd.com/1/

and their motto:

ANSWERING YOUR HYPOTHETICAL QUESTIONS WITH PHYSICS, EVERY TUESDAY

And, remember, every Thursday "The Big Bang Theory" airs on CBS (sorry, just a plug for my favorite TV show).

[Jocko]

Thanks. I don't think I'm going to the discussion group, though. Taking my brain ther would be like drawing down on Billy the kid with a slingshot! I'm WAY outgunned. Hahaha.

The atmospheric conditions would certainly affect the extent of the expansion of the fireball. It's exactly as you say: the density of the air is important. This effect was worked out back in the 1940s as part of understanding the nuclear tests. I've seen it applied to supernovae explosions (same idea, the density of interstellar gas affects the range and rate of expansion of the shock wave).

But, if you ask me about how large the effect would be, that's a detail a "back of the envelope" calculation would not so easily capture. So, I don't have that answer.

I think the website where the OP comes from will be posting such discussions weekly. I doubt they will be baseball related much of the time, but I think they want to address "everyday" things, and they welcome submitted questions. The site is http://what-if.xkcd.com/1/

and their motto:

ANSWERING YOUR HYPOTHETICAL QUESTIONS WITH PHYSICS, EVERY TUESDAY

And, remember, every Thursday "The Big Bang Theory" airs on CBS (sorry, just a plug for my favorite TV show).