Baseball at relativistic speeds and other wild hypotheticals

Randall "XKCD" Munroe's new "What If?" feature answers one wild hypothetical per week. The first two are corkers: Relativistic Baseball baseball asks what would happen if a baseball pitcher could throw a ball at 0.9C; the second, SAT Guessing, looks at the (very long) odds against getting a perfect SAT by bubbling in random guesses. Here's a taste of Relativistic Baseball:

The ball is going so fast that everything else is practically stationary. Even the molecules in the air are stationary. Air molecules vibrate back and forth at a few hundred miles per hour, but the ball is moving through them at 600 million miles per hour. This means that as far as the ball is concerned, they’re just hanging there, frozen.

The ideas of aerodynamics don’t apply here. Normally, air would flow around anything moving through it. But the air molecules in front of this ball don’t have time to be jostled out of the way. The ball smacks into them hard that the atoms in the air molecules actually fuse with the atoms in the ball’s surface. Each collision releases a burst of gamma rays and scattered particles. fusion illustration fusion zone of baseball

These gamma rays and debris expand outward in a bubble centered on the pitcher’s mound. They start to tear apart the molecules in the air, ripping the electrons from the nuclei and turning the air in the stadium into an expanding bubble of incandescent plasma. The wall of this bubble approaches the batter at about the speed of light—only slightly ahead of the ball itself.

What if?


  1. The SAT one annoyed me, because the actual perfect score is normed. So the same number of people (approximately) are going to get a 2400 each year, and they adjust the test in order to get the specificity they were looking for. (I need Randall Munroe to teach me about the velociraptor threat, not how to multiply fractions for probability…)

    1. Right, so you can miss a few answers and still get a “perfect” score. That puts the math off, but not by much.

      Having taught SAT prep for a spell (and taken a bunch of practice tests in the process), it’s a nice feeling knowing when you score a perfect, and not just a 2400.

      I don’t recall how many questions you can miss total (and it’s not equal for each category of questions), but I don’t believe it was more than four or five.

    2.  The SAT one annoyed me, because you don’t lose points for leaving answers blank. You get +1 point for a correct answer, -0.25 point for an incorrect answer, and 0 points for a blank answer.

  2. What I got out of it is that if Superman moved so fast that you couldn’t see him, he’d create a nuclear explosion.

    “Wait here, Lois. I’ll save the day!” ::Boom:: There goes Metropolis.

    1. You don’t have to move at the speed of light to be faster than human vision can pick up. “Faster than the eye can see” is not even remotely close to the speed of light.

      1.  That hasn’t stopped Superman from moving at near the speed of light on many occasions though.  Heck, he’s done it for frivolous reasons like racing the Flash around the world (presumably leaving a trail of radiated devastation behind). 

        1. Superman can go the speed of light while in outerspace, because there’s almost no air resistance. As for racing the Flash, that was for charity.

          The Flash on the other hand can walk through walls, so him being able to move nearly the speed of light in-atmosphere would make slightly more sense.

  3. Baseball leading to mushroom clouds… I wonder if someone’s been reading Underworld…. :)

    1. Actually all I could think about was Dragon Ball Z…
      Kamehameha was really just throwing a pebble at near light speeds.

  4. The final little subtitle, about the runner advancing to first, is so priceless.  Pitch-perfect bathos.

      1. While that’s true in theory, in practice the context in which a batter’s effort or lack thereof to avoid being hit is often taken into consideration by umps: speed and movement of pitch, lighting (see Ray Chapman’s death), etc.

  5. 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.

    1. As long as the fragments constituting “the batter” provide their own motive force, and stay within the baseline, on their way to first base; 6.09(c).

  6. What happened there with your “whatif04.png.jpg.gif”? Has your PS got multiple personality disorder or does it just hate the 253 shades of grey?

    Here’s a better one for you. Invoice is in the mail ;)

    1. yours doesn’t have full transparency on the background (not that it’s needed here, since boingboing has a white background anyway, but whatever). that’s where it gets a little harder. sure, it’s still easy, just index the intensity to the alpha channel, but i couldn’t figure it out in 10 minutes with GIMP.

  7. @retchdog:disqus The original on XKCD has a transparent BG already. Gifs tend to handle transparency worse than PNG-24 which is why I saved it without. But if you wanna get fancy then just save the original XKCD, open in PS, Copy and transform to suit BB sized canvas, Save for Web as transparent PNG24 (Ends up ~8k bigger in filesize than the gif version).

    If you really need one, here you go

    My recommendation: Get PS :P
    (seems disqus hates .pngs)

    1. Weird.  The thumbnail is black, but if you click it you get the image.  If you click the link, you get a very grayed out image.

      1. some odd side effect of an image of a cartoon showing a .9c baseball? Just be glad your display does not show the X-rays

          1. Well maybe he will end up like the pitcher if someone gets a too realistic rendering of the cartoon

  8.  This is exactly what a Master of Orion 2.5 needs in it’s endgame. Someone really does need to make a proper sequel to MOO 2. MOO 3 was a joke. There needs to a relativistic projectile weapon in the force fields tree. Mounted on a ship it takes out any ship in one shot, but it might miss. Mounted as a planetary defense, it does more damage than the Stellar Converter, but might miss. Research to hyper advanced and you can fire it from one star system to another if you have jump gates or star gates. Renders Desert or better planets to barren.

  9. According to my calculations, a 5-ounce baseball at 0.9c would have a kinetic energy of just about 4 megatons.  So yeah, it’d make quite a mess.

    1. That just makes me want to get 4 megatons of TNT and a baseball to see how fast I can get it to go.

      1. Unfortunately most of the energy would go into accelerating the mass of the TNT itself. So, not very fast – at most a few km/s. Unless you use the TNT as fuel to generate electricity and drive a linear accelerator.

        1. Whoops, I meant 4 megaton /equivalent/ of TNT. So, plop a sphere of plutonium or whatever they use into a /really good/ cannon, ram a baseball down there, and… stand back.

    2. What percentage of the particles making up the ball would just fly straight out of the Earth’s atmosphere and into space, though? I wonder if the percentage might be fairly close to 100%, in which case it could be that significantly less than 4 megatons of energy would be converted into heat and light on Earth, and the effects might not actually be as disastrous as Randall suggests. Also, the energy lost as heat and light might be spread out over a long path within the atmosphere rather than concentrated around the point where the ball begins to move at 0.9c.

  10. I thought from the outset, 0.9c is ridiculous overkill. Even at ‘just’ 0.1c the energies involved would be [insert big adjective].

  11. I believe I have spotted a flaw. 

    The article states: “It [the shock wave] hits the bat first, but then the batter, plate, and catcher are all scooped up and carried backward through the backstop as they disintegrate.”

    Earlier however it states: “The batter hasn’t even seen the pitcher let go of the ball, since the light carrying that information arrives at about the same time the ball does.” 

    Unless this was an attempted bunt, I cannot possibly see how the remains of the ball and could have hit the bat first.

  12. The analysis did not take into account how the ball was accelerated to its super speed. What happened with the pitcher’s arm, and how much force did he need to use to throw and keep a grip on the ball as it accelerated?

    1. Or it was the first sentence of the analysis: “Let’s set aside the question of how we got the baseball moving that fast. We’ll suppose it’s a normal pitch, except in the instant the pitcher releases the ball, it magically accelerates to 0.9c.”

  13. I always wondered how fast you would have to throw an egg into a frying pan to generate enough frictional heat to have an instant omelette. The egg is assumed to stay inside the pan.

    Likewise, how fast do you have to throw an egg in the air to generate enough aerodynamic friction to have it boiled upon landing? Mach 3?

  14. I think the fusion part is exaggerated here, and that most of the energy exchanged would be in electromagnetic scattering of the nuclei rather than nuclear interactions. The nuclei only take up a minute fraction of the volume of their host atoms, after all.  Approximating the molecular makeup of the ball by something between wax and sugar, at 44mm diameter, it’s effective nuclear area is only about 375 micrometers^2. The column of air at 80% N2 and 20% O2 only presents a cross section of around 50 micrometers^2. I’m pretty sure that the nuclei would largely pass each other by over a mere 18 meters of flight. The result wouldn’t be much less spectacular. The ball would pass through the batter and the stands before their bodies realized they’d been scheduled to explode. No one would have time to notice though.

    1. Further calculation gives around 10^21 nucleus on nucleus collisions between the mound and the plate–about 1 in 2500 nuclei over the given volume. At 9/10 c, the kinetic energy is more than 800MeV / nucleon–much more than the nuclear binding energy, so the nuclei would be blasted apart, RHIC-style.

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