What-If 0001: "Relativistic Baseball"

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What-If 0001: "Relativistic Baseball"

Postby Yakk » Tue Jul 10, 2012 6:59 pm UTC

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

"A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base."

I'm wondering how far the baseball would get before it effectively detonated -- I'm surprised the effect wouldn't be more directional?

I suppose the momentum (the vector component of the event) is relatively small compared to the energy, in effect.

(Is this the appropriate forum?)
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Re: What-If 0001: Relativistic Baseball

Postby jpers36 » Tue Jul 10, 2012 7:12 pm UTC

There's a #2 as well ...

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Re: What-If 0001: Relativistic Baseball

Postby Kaiman » Tue Jul 10, 2012 7:34 pm UTC

This is why the movie Eraser is totally bunk. That bullet would have obliterated entire city blocks.

A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.


That was an excellent way to end the analysis.

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Re: What-If 0001: Relativistic Baseball

Postby zagarus » Tue Jul 10, 2012 9:19 pm UTC

The ball wouldn't have the time to split into tiny particles, as described. It would merely vaporize into atoms in various states of ionization (forming a plasma). Formation of particles requires that it break up slower than the speed of sound in the material. The atoms of the plasma itself wouldn't have the kinetic energy to ignite fusion in the air, otherwise the yield of nuclear explosions would be dramatically higher than they are. There was a concern in the early days of nuclear weapons development that a nuclear explosion could ignite the whole atmosphere in a spectacular fusion reaction, but it was quickly calculated to be impossible.

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Re: What-If 0001: Relativistic Baseball

Postby indelibleone » Tue Jul 10, 2012 9:59 pm UTC

I think that the energy per particle would pull the ball apart well before this happened .The ball would have so much kinetic energy that the thermodynamic limits of combustion would kick in quicker as (3/2*K_boltzman*T) = K.E. Since the before and after velocity difference is too much, the ball would much more likely disintegrate. One should model this to be sure, but fusion is just absurd. The air would more likely "crack" around the ball and lightning would strike through the sub-atmoic particle shower carved pathways thus incinerating the ball anyways.

The lightning is a far less likely scenario because it assumes the ball is a hard surface.

So basically Randall's situation can only occur for an indestructible baseball (I guess that's the magic he is talking about). The lightning case for a less hard but still hard ball, and for a realistic baseball: a ball of fire.

Basically at these energies, everything literally falls apart as the binding energy is not enough to hold it together.

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Re: What-If 0001: Relativistic Baseball

Postby RepoMan » Tue Jul 10, 2012 10:23 pm UTC

I got curious about the numbers (unexpectedly sparse in this post), and some simple surfing plus the awesome Wolfram Alpha yielded this:

(255 grams times ((0.9 times the speed of light) squared)) divided by 1 megaton of TNT
=
4.44

So the 0.9c baseball is the equivalent of almost a 4.5-megaton nuclear bomb. DAAAAAANG. According to Wikipedia (http://en.wikipedia.org/wiki/Nuclear_weapon_yield), the most powerful nukes in active US service are only 1.2 megatons, so it'd be almost four of those at once.

Moral: DON'T THROW BASEBALLS THAT FAST.

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Re: What-If 0001: Relativistic Baseball

Postby Max™ » Tue Jul 10, 2012 10:39 pm UTC

Indeed it is, I loved "unsuspecting batter" as well.

Reminded me of Starfall.
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Re: What-If 0001: Relativistic Baseball

Postby Faramir » Tue Jul 10, 2012 10:45 pm UTC

A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.


6.08
The batter becomes a runner and is entitled to first base without liability to be put out (provided he advances to and touches first base) when --
...
(b) He is touched by a pitched ball which he is not attempting to hit unless (1) The ball is in the strike zone when it touches the batter, or (2) The batter makes no attempt to avoid being touched by the ball;
If the ball is in the strike zone when it touches the batter, it shall be called a strike, whether or not the batter tries to avoid the ball. If the ball is outside the strike zone when it touches the batter, it shall be called a ball if he makes no attempt to avoid being touched.


Based on my understanding of Randall's description, the ball has disintegrated by the time it reaches home plate, so it seems like there is nothing left to touch the batter. Are we assuming that being hit by the blast wave counts as being hit by the ball, since it will contain particles from the ball?

I swore there was an official rule about what happened if pieces came off a ball during play (e.g. hit so hard the cover comes off), but I can't find it. I'm pretty sure that the larger piece would be considered the live ball. In this case, if the ball is disintegrated, either there will be no live ball left or one particle (the last to be stripped away?) would be the "live ball", but since it will be microscopic, there's no way to know whether it touched the batter or not.

On the other hand, if we consider this as the pitcher "defacing the ball", then by Rule 8.02(a)(5) the pitcher (what's left of him) will be ejected from the game and suspended by the league.

Obviously this a question the MLB Rules Committee needs to look into.

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Re: What-If 0001: Relativistic Baseball

Postby egaku » Tue Jul 10, 2012 10:47 pm UTC

So how fast could a baseball, or whatever, travel in the atmosphere before it causes massive death?

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Re: What-If 0001: Relativistic Baseball

Postby jello34543 » Tue Jul 10, 2012 11:20 pm UTC

XKCD wrote:A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.


Respectfully, I must disagree with this interpretation of 6.08(b). It is my understanding that if any part of the ball passes through the strike zone, it is a strike. If we assume the ball is thrown as a non-relativistic strike, then the bullet sized core which makes it to the plate should as well. In addition, any number if shredded fragments are likely to pass over the plate as well. Therefore, under 6.08(b)(1) the batter would not be eligible to advance to first base.

In addition, regardless of being called as a ball or strike, we are assuming that the light from the thrown pitch and the ball itself arrive at essentially the same time (unsuspecting batter). As such, the batter lacks the reaction time to attempt to avoid the pitch, and therefore would also not be eligible to advance under rule 6.088(b)(2).

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Re: What-If 0001: Relativistic Baseball

Postby gmalivuk » Tue Jul 10, 2012 11:43 pm UTC

RepoMan wrote:(255 grams times ((0.9 times the speed of light) squared)) divided by 1 megaton of TNT
=
4.44
Except, baseballs are more like 145 grams, and you can't use Newtonian kinetic energy for something going a sizable portion of the speed of light.

The actual kinetic energy in this case is (.145kg)(299792458m/s)2(1/sqrt(1-0.92) - 1), or 1.7e16 J, equivalent to 4.03mt.

(Note that at 0.866c, an object's kinetic energy is equal to its rest mass (as energy), which is what you'd get if you reacted half its mass in normal matter with the same amount of pure antimatter.)
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Re: What-If 0001: Relativistic Baseball

Postby clockworkbookreader » Wed Jul 11, 2012 1:08 am UTC

And 4.44 mt vs 4.03 mt is going to make a big difference to the pitcher, the batter, and the poor fool sitting on the hill watching. (no, no! He's only MOSTLY atomized and caught up in the plasma ball).

I understand the need to be right and to make sure the math is correct, but in this case we ARE talking of horseshoes, hand grenades, and nuclear events.
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Re: What-If 0001: Relativistic Baseball

Postby gmalivuk » Wed Jul 11, 2012 1:11 am UTC

It's just coincidentally that close because the extra 110g RepoMan used for the ball's mass more than balanced the underestimate given by the non-relativistic kinetic energy calculation. If the ball were actually 255g, it would be 7.09mt.
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Re: What-If 0001: Relativistic Baseball

Postby Pfhorrest » Wed Jul 11, 2012 1:48 am UTC

jello34543 wrote:It is my understanding that if any part of the ball passes through the strike zone, it is a strike.

Not that this is directly relevant, but: what if the ball deflects off the batter, then through the strike zone?
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Re: What-If 0001: Relativistic Baseball

Postby brakos82 » Wed Jul 11, 2012 1:54 am UTC

Pfhorrest wrote:
jello34543 wrote:It is my understanding that if any part of the ball passes through the strike zone, it is a strike.

Not that this is directly relevant, but: what if the ball deflects off the batter, then through the strike zone?


I think you'd get a turkey?

Or in this case, an unsuspecting plasma turkey.
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Re: What-If 0001: Relativistic Baseball

Postby ivnja » Wed Jul 11, 2012 2:01 am UTC

Pfhorrest wrote:Not that this is directly relevant, but: what if the ball deflects off the batter, then through the strike zone?

If the batter makes some effort to not be hit and it still hits him outside the strike zone, it should be a free base no matter where the ball ends up afterward.
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Re: What-If 0001: Relativistic Baseball

Postby PhoenixEnigma » Wed Jul 11, 2012 2:04 am UTC

Faramir wrote:On the other hand, if we consider this as the pitcher "defacing the ball", then by Rule 8.02(a)(5) the pitcher (what's left of him) will be ejected from the game and suspended by the league.
I'm pretty sure they'll be forcefully ejected from the game in this instance, regardless of what the rules may say.
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Re: What-If 0001: Relativistic Baseball

Postby TheGrammarBolshevik » Wed Jul 11, 2012 2:06 am UTC

jello34543 wrote:
XKCD wrote:A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.


Respectfully, I must disagree with this interpretation of 6.08(b). It is my understanding that if any part of the ball passes through the strike zone, it is a strike. If we assume the ball is thrown as a non-relativistic strike, then the bullet sized core which makes it to the plate should as well. In addition, any number if shredded fragments are likely to pass over the plate as well. Therefore, under 6.08(b)(1) the batter would not be eligible to advance to first base.

In addition, regardless of being called as a ball or strike, we are assuming that the light from the thrown pitch and the ball itself arrive at essentially the same time (unsuspecting batter). As such, the batter lacks the reaction time to attempt to avoid the pitch, and therefore would also not be eligible to advance under rule 6.088(b)(2).

You make a fair point. Of course, even if the runner were to be awarded a base it would have to be a substitute under 5.10(c)(1) and the game should be suspended under rule 4.12(a)(3) because of damage to the field equipment. These actions would be carried out by a replacement umpire under rule 9.02(d).

Pfhorrest: The ball becomes dead when it hits the batter, so it cannot be a strike regardless of where it goes.

However, on a literal reading the batter is awarded a base if he attempts to avoid a pitch and is struck by it after it has passed through the strike zone.
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Re: What-If 0001: Relativistic Baseball

Postby Max™ » Wed Jul 11, 2012 2:07 am UTC

PhoenixEnigma wrote:
Faramir wrote:On the other hand, if we consider this as the pitcher "defacing the ball", then by Rule 8.02(a)(5) the pitcher (what's left of him) will be ejected from the game and suspended by the league.
I'm pretty sure they'll be forcefully ejected from the game in this instance, regardless of what the rules may say.

Well, parts of them could wind up fused with the nuked topsoil.
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Re: What-If 0001: Relativistic Baseball

Postby Yakk » Wed Jul 11, 2012 3:03 am UTC

indelibleone wrote:I think that the energy per particle would pull the ball apart well before this happened .The ball would have so much kinetic energy that the thermodynamic limits of combustion would kick in quicker as (3/2*K_boltzman*T) = K.E.

First, I am under the impression that combustion will take too long. Things will have gone pear shaped by the time you have combustion.

Second, the equation you are using isn't for parallel, highly ordered motion -- but rather, the amount of K.E. that random motion (temperature) implies.
Since the before and after velocity difference is too much, the ball would much more likely disintegrate.

The moment of acceleration from mundane to 0.9c velocity is magical, as explicitly described in the post.

Getting that baseball up to 0.9c has its own interesting issues. But those are explicitly hand-waved.
One should model this to be sure, but fusion is just absurd. The air would more likely "crack" around the ball and lightning would strike through the sub-atmoic particle shower carved pathways thus incinerating the ball anyways.

Fusion doesn't look very absurd to me. 0.9c is fast. The repulsion between nuclei could be overwhelmed at that velocity: I'd be worried that the velocity would be too high for the nuclei to capture each other!

RHIC is (wikipedia source) 99.995c, but it produces quark-gluon plasma.

Alpha particles move at (again wikipedia) 0.05c, and are quite capable of triggering fusion.

Doing a quick bit of math:
4.002602 * 1.6 * 10^(-27) kg * c^2 / (28300.7 *1000 * 1.6*10^(-19) J) =~ 127
the mass-energy of a helium-4 nucleus is 127 times the binding energy of said nucleus. And at 0.9c, the KE of a nucleus is greater than its mass-energy. Basically, I think fusion might be an overly low-temperature description of what happens when a 0.9c baseball flies through the atmosphere...

(The ratio for C-12 is only 117 (mass energy vs binding energy)).

I suspect rather than Fusion, we'd get Fission (which would cool the baseball down from the energy of the impact!), as the impact would split nuclei into pieces with higher binding energy than what they started with?

Meh.
So basically Randall's situation can only occur for an indestructible baseball (I guess that's the magic he is talking about). The lightning case for a less hard but still hard ball, and for a realistic baseball: a ball of fire.

Fire is too cold for what will be going on. Fire is a hot gas. What is going on with that baseball is that the binding energy of nuclei 2 orders of magnitude smaller than the kinetic energy of the nuclei. And when it hits another nuclei, energy changes hands -- and even a glancing collision is enough to shatter both nuclei. Direct fusion doesn't look likely, because there isn't enough mass in the ball-width between the pitcher and the batter to get the energy-per-subatomic particle low enough for things to form a nuclei...

I suppose you could bleed off most of the energy in the form of ridiculously high-energy radiation, giving your baseball and air particles a chance to cool down and merge, but my uneducated napkin calculations makes that seem unlikely.

Secondary fusion, where the wave of emitted high-energy photons from the initial baseball-air collisions, smash into the air and give things enough of a kick to fuse, seems more reasonable. Maybe that is what is going on with the fusion -- fusion of air-to-air nuclei, not baseball-to-air nuclei?
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Re: What-If 0001: Relativistic Baseball

Postby zombie_monkey » Wed Jul 11, 2012 12:02 pm UTC

Someone over at James NIcoll's blog said the same thing:

http://james-nicoll.livejournal.com/3849919.html?thread=72400831#t72400831
The xkcd description talks about fusion, but at those speeds the kinetic energy of the nuclei far exceeds their nuclear binding energy. The nuclei would undergo spallation, shattering into smaller fragments and free protons and neutrons, together with production of pions and other mesons.

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Re: What-If 0001: Relativistic Baseball

Postby rmsgrey » Wed Jul 11, 2012 1:08 pm UTC

Of course, at sufficiently high speeds (.9c may well not be high enough) the relativistic baseball simply isn't around long enough to dump enough energy to cause a problem - most of the energy ends up carried into deep space rather than forming a mushroom cloud in the stadium. Sure, individual atoms in the way get shredded, but surely there just isn't time for much of the energy to get dumped into the surroundings...

You'd need there to be enough mass in the way to drop the ball's speed down to around the (local) speed of sound for energy to bleed off significantly - an air-atom colliding with a ball-atom will give two atoms still traveling at nearly half the speed of light in the ball's original direction - you need to slow down a lot before any lateral component of motion becomes significant.

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Re: What-If 0001: Relativistic Baseball

Postby reluctantsaints » Wed Jul 11, 2012 1:18 pm UTC

I haven't read the rest of this thread, but I want to say that out of all of the things that I read this morning, some of which were trying quite harder to make me laugh, this succeeded the most-- simply with the last line.

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Re: What-If 0001: Relativistic Baseball

Postby snowyowl » Wed Jul 11, 2012 4:32 pm UTC

rmsgrey wrote:Of course, at sufficiently high speeds (.9c may well not be high enough) the relativistic baseball simply isn't around long enough to dump enough energy to cause a problem - most of the energy ends up carried into deep space rather than forming a mushroom cloud in the stadium. Sure, individual atoms in the way get shredded, but surely there just isn't time for much of the energy to get dumped into the surroundings...

You'd need there to be enough mass in the way to drop the ball's speed down to around the (local) speed of sound for energy to bleed off significantly - an air-atom colliding with a ball-atom will give two atoms still traveling at nearly half the speed of light in the ball's original direction - you need to slow down a lot before any lateral component of motion becomes significant.


Yes, I think the ball will easily escape the Earth's gravity and carry off most of its kinetic energy into deep space. But the X-rays thrown off by the nuclear reactions will still be very impressive, and I'd expect air molecules just close enough to the ball to be pulled along in its slipstream but not close enough to actually hit it would dump most of their energy into the environment. There would definitely be a sizeable explosion.
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Re: What-If 0001: Relativistic Baseball

Postby Manabu » Wed Jul 11, 2012 4:49 pm UTC

I found it very amusing. But is it really a 4.03mt nuclear explosion? Will every atom in the ball be fusioned? And how much air and other materials will take part in the fusion reaction?

Outside this highly hypothetical situation, high speed atmospheric re-entry and hypersonic fight also have non-trivial air resistance effects. The air can't get out of the way fast enough, so it's pressure and temperature rises. At high temperatures, the gas become chemically reactive, and those chemical (not nuclear, thankfully) reactions modify it's own proprieties and state. Wikipedia has a nice article about it: http://en.wikipedia.org/wiki/Atmospheric_entry

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Re: What-If 0001: Relativistic Baseball

Postby Max™ » Wed Jul 11, 2012 4:52 pm UTC

Compress the atmosphere ahead of the ball until it reaches the same density as the ball itself, see how far that would take.

Now accelerate the process and see how long the ball survives.

Don't think it would fuse completely, but I wouldn't want to be around to find out.
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Re: What-If 0001: Relativistic Baseball

Postby gmalivuk » Wed Jul 11, 2012 7:06 pm UTC

Manabu wrote:I found it very amusing. But is it really a 4.03mt nuclear explosion? Will every atom in the ball be fusioned?
No fusion has to happen, because 4.03mt isn't a nuclear explosion. It's just the amount of kinetic energy in a baseball moving at 0.9c. If there's fusion, that's *additional* energy released, on top of that. As mentioned a couple of times, though, if there is fission instead (which is probably more likely given the velocity) this will take away some of the energy, because most of the atoms involved are relatively small and thus absorb energy in fission rather than releasing it like, say, uranium does. This would reduce the portion of that 4.03mt of energy that quickly turns into dangerous heat or radiation.

However, even if *all* the (non-hydrogen) atoms in the ball (and a similar mass of atmospheric atoms) fission, it would only account for a percent or two of that total kinetic energy.
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Re: What-If 0001: Relativistic Baseball

Postby forbiddenSpell » Wed Jul 11, 2012 7:58 pm UTC

"The .9c pitch is the best thing that happened to baseball!"

"But it's not the same game!"

"It's better!"

"No it's not!"

"Cause the batter comes up and he's vaporized..."

"He can bunt!"

"Whatever."

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Re: What-If 0001: Relativistic Baseball

Postby firechicago » Wed Jul 11, 2012 8:25 pm UTC

Max™ wrote:Compress the atmosphere ahead of the ball until it reaches the same density as the ball itself, see how far that would take.

Now accelerate the process and see how long the ball survives.

Don't think it would fuse completely, but I wouldn't want to be around to find out.


But as the original article points out, the atmosphere will not compress appreciably in front of the ball. For that to happen, the atoms of the air in front of the ball would have to hit its surface and then bounce off, which is highly unlikely at .9c. They're much more likely to either pass right through the ball or fission/fuse with the atoms in the ball. At these relative speeds it's much more accurate to think of the ball as colliding with a stationary array of air molecules, rather than moving aerodynamically through a gas.

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Re: What-If 0001: Relativistic Baseball

Postby Yakk » Wed Jul 11, 2012 9:19 pm UTC

Baseball stadiums usually have stuff behind the catcher.

And 0.9 c / (11,190 km/s) =~ 24, so it wouldn't take much solid matter (24 times the mass of the baseball) to soak up the momentum of that baseball to below escape velocity. Roughly 24 ball-widths worth of baseball-density matter, or 1.8 meters. So a concrete pillar would get in the way, but the wall of a house wouldn't be noticed.

Air is roughly 1000 times less dense than a ball (presuming the ball, like most matter on the planet Earth, is about as dense as water). So you'd need 24000 ball-widths to reduce the ball to escape velocity. Using 7.5 cm for a baseball, that is only 1.8 km. So, much like an alpha particle, its kinetic energy could be soaked up by the atmosphere pretty quickly (for its size!)

Then again, the x-ray and other fronts from secondary effects might clear stuff out of the way, allowing the core of the ball to penetrate. On the other hand, the matter in front of the baseball doesn't have much time to get out of the way until the baseball slows down.
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Re: What-If 0001: Relativistic Baseball

Postby ppomes » Wed Jul 11, 2012 10:37 pm UTC

I think there is an omitted word (so) in the phrase, "The ball smacks into them [so] hard that the atoms [...]"

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Re: What-If 0001: Relativistic Baseball

Postby Max™ » Thu Jul 12, 2012 12:33 am UTC

Yakk wrote:Baseball stadiums usually have stuff behind the catcher.

And 0.9 c / (11,190 km/s) =~ 24, so it wouldn't take much solid matter (24 times the mass of the baseball) to soak up the momentum of that baseball to below escape velocity. Roughly 24 ball-widths worth of baseball-density matter, or 1.8 meters. So a concrete pillar would get in the way, but the wall of a house wouldn't be noticed.

Air is roughly 1000 times less dense than a ball (presuming the ball, like most matter on the planet Earth, is about as dense as water). So you'd need 24000 ball-widths to reduce the ball to escape velocity. Using 7.5 cm for a baseball, that is only 1.8 km. So, much like an alpha particle, its kinetic energy could be soaked up by the atmosphere pretty quickly (for its size!)

Then again, the x-ray and other fronts from secondary effects might clear stuff out of the way, allowing the core of the ball to penetrate. On the other hand, the matter in front of the baseball doesn't have much time to get out of the way until the baseball slows down.

That's what I meant.

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Re: What-If 0001: Relativistic Baseball

Postby NukemHill » Thu Jul 12, 2012 1:09 am UTC

A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.


Frankly, that pitcher's facing a hell of a fine. After all, he's just thrown at the batter ... the umpire, the on-deck hitter, the entire bench for both teams ... every fan in the stands ... and every living creature within a square mile.

I think the commissioner is going to have something to say about this....

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Re: What-If 0001: Relativistic Baseball

Postby jareds » Thu Jul 12, 2012 1:23 am UTC

Adam Savage: You're probably asking, "Adam, why are you in a bunker on the Moon?"! I'll tell you. Earlier today, the Bussard ramjet we launched 10 years ago re-entered the outer solar system. In just a few minutes, it will fly by the Moon at 90% of the speed of light! Several hundred milliseconds ahead of time, it will release a baseball [holds up baseball] with a very slight nudge that puts it on a path almost exactly tangent to the lunar surface. If everything goes according to plan, that baseball will enter a hole in the outer wall of our full-scale replica moon colony! [points to scale model] It will then travel down a perfectly straight, vacuum-filled tube for three miles until it reaches the end of the tube here [cut to camera on location] -- the pitcher's mound of our baseball diamond. It will puncture the seal and proceed toward home plate, where Buster is waiting. [cut to crash-test dummy wearing a baseball unifornm] Jamie, are you as excited as I am?!

Jamie Hyneman: Well, this is our biggest build yet. I hope it works.

Adam Savage: I do too!

...

[Cut to Adam and Jamie in space suits standing next to a crater next to an enormous containment wall that's been torn open. Adam looks dejected; Jamie looks like Jamie.]

Jamie Hyneman: Well, the ultra-high speed camera suggests that the ball started to scrape the Moon's surface a hundred yards before it reached the outer wall. Even if it weren't for the surface, it still would have missed the tube by at least seven feet. We'll have to rethink our guidance system, reset, and try again.

Adam Savage: I really hope it works next time. That will be our last ramjet. If something goes wrong again, I think that'll be it for this myth.

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Re: What-If 0001: Relativistic Baseball

Postby Max™ » Thu Jul 12, 2012 2:24 am UTC

O.o

Fund it.
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Re: What-If 0001: Relativistic Baseball

Postby elminster » Thu Jul 12, 2012 8:24 am UTC

Personally, I would have thought the ball would generate enough energy that the entire ball would vaporize (or at least no longer be in a solid state) well before reaching the batter. I'm guessing the fission caused by hitting the air atoms in front of it would probably be enough energy to raise the temp to more than enough to do that.
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Re: What-If 0001: Relativistic Baseball

Postby Pfhorrest » Thu Jul 12, 2012 9:00 am UTC

If the ball is moving so fast that the air molecules are effectively stationary for the entire course of its motion, then no thermal energy is going to propagate through the ball and cause chemical reactions like combustion or state changes like vaporization. We're dealing with speeds so fast and periods of time so small that modeling things as fluids and solids with chemical and thermodynamic properties isn't really applicable because not enough small-scale mechanical events have time to occur for those larger-scale aggregate phenomena to even make coherent sense. It's really better modeled as a bunch of individual atoms knocking around at this scale. And a baseball-sized chunk of such atoms are flying at 0.9c, and don't give much of a fuck if some high-energy photons are bouncing back at them, they can bounce right back off thankyouverymuch without slowing down these baseball atoms significantly at all. All those scattered nitrogens and carbons and oxygens in the way will make an effect eventually, but it's something like the effect of a semi-truck barreling down a street at 200mph running into a crowd of people. Yes, they will slow it down... eventually. And my orders of magnitude here are probably off; it's more like the truck (the baseball) is traveling so fast it will plow through a few hundred miles of people (atoms in the air) before they finally slow it to a stop. The stopping effect of the blood splattering on the windshield (the gamma ray bursts from the smashed atoms) is negligible by comparison, and the truck may crumple or even get smashed apart as it plows through the crowd, but the wreckage of that truck is still booking it and doing similar damage as it goes. Inertia's a bitch.

I didn't mean for this metaphor to become so gruesome, honestly.
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Re: What-If 0001: Relativistic Baseball

Postby solune » Thu Jul 12, 2012 9:12 am UTC

Frankly, that pitcher's facing a hell of a fine. After all, he's just thrown at the batter ... the umpire, the on-deck hitter, the entire bench for both teams ... every fan in the stands ... and every living creature within a square mile.

I think the commissioner is going to have something to say about this....


I think the pitcher should only be held responsible for direct interactions of the ball's particles with the public. The velocity given to the air around the ball, photons bouncing on the ball or emitted from it are hardly his responsibility.
And, as it is unlikely that an atom from the ball would survive a 90° turn (or even a 1° turn), only the people in direct line of the ball will be "touched" by it

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Re: What-If 0001: Relativistic Baseball

Postby Yakk » Thu Jul 12, 2012 1:57 pm UTC

Chemical reactions are too slow and too low energy to matter "near" the baseball. Fusion is too slow and too low energy to matter, other than as secondary effects, near the baseball.

Actually, we may hit quark gluon plasma -- or at least we have a chance to! Most of the "rest mass" of a proton is in its quark-gluon binding energy. And rest mass = K.E. at ~83% of the speed of light. So a collision at 90% of the speed of light has enough energy hanging around to cook quarks and gluons apart. It won't last long, and there isn't enough to convert the baseball and what it collides with into quark-gluon plasma entirely, but in the chaos of the collisions some parts are going to get "extra hot" I suspect.

The first collisions will tear nuclei into component protons and neutrons, which will couple madly and cool down. Some of those might collide with other particles going in another direction and turn into quark-gluon plasma? I'm really not sure, too many billiard balls to think about.

I wonder what happens when one of those high-energy electrons plows into a nucleus? Probably not all that exciting compared to nucleus-nucleus collisions.

So I've noted that treating things as chemicals is silly. Given that the KE is ~2 orders of magnitude higher than the binding energy of nuclei, should treating the particles as atoms be equally silly? Probably. The energy lost by splitting the nucleus is far below the threshold of the napkin math I'm doing.

I do find it interesting that the binding energy of a nucleus is a lower order value than the KE required to have that nucleus to escape Earth's gravitational pull?! I must be making a mistake here. What is it?

They should have sent a particle physicist.
One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision - BR

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Re: What-If 0001: Relativistic Baseball

Postby iamspen » Thu Jul 12, 2012 2:41 pm UTC

I realize he can throw the ball at 0.9c, but man, that pitcher has some poor mechanics.


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