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Sep. 04, 2014

Could You Hit a Baseball Pitched Near the Speed of Light?

by Randall Munroe

Click to enlarge images
Tune in to SciFri on September 5, 2014 to hear Randal Munroe ponder zany math and science questions like the one below. 
 
Q. What would happen if you tried to hit a baseball pitched at 90 percent the speed of light? — Ellen McManis
 
{"input":{"width":490,"photo":"pitch1","row":"4981","table":"DOCUMENT"}}

 
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. From that point onward, everything proceeds according to normal physics.

A. The answer turns out to be “a lot of things,” and they all happen very quickly, and it doesn’t end well for the batter (or the pitcher). I sat down with some physics books, a Nolan Ryan action figure, and a bunch of videotapes of nuclear tests and tried to sort it all out. What follows is my best guess at a nanosecond-by-nanosecond portrait.
 
The ball would be going so fast that everything else would be practically stationary. Even the molecules in the air would stand still. Air molecules would vibrate back and forth at a few hundred miles per hour, but the ball would be moving through them at 600 million miles per hour. This means that as far as the ball is concerned, they would just be hanging there, frozen.
 
The ideas of aerodynamics wouldn’t apply here. Normally, air would flow around anything moving through it. But the air molecules in front of this ball wouldn’t have time to be jostled out of the way. The ball would smack into them so hard that the atoms in the air molecules would actually fuse with the atoms in the ball’s surface. Each collision would release a burst of gamma rays and scattered particles.**
 
{"input":{"width":490,"photo":"fusionzone2","row":"4981","table":"DOCUMENT"}}
{"input":{"width":490,"photo":"fusiondiagram3","row":"4981","table":"DOCUMENT"}}
 
These gamma rays and debris would expand outward in a bubble centered on the pitcher’s mound. They would 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 would approach the batter at about the speed of light—only slightly ahead of the ball itself.
 
The constant fusion at the front of the ball would push back on it, slowing it down, as if the ball were a rocket flying tail-first while firing its engines. Unfortunately, the ball would be going so fast that even the tremendous force from this ongoing thermonuclear explosion would barely slow it down at all. It would, however, start to eat away at the surface, blasting tiny fragments of the ball in all directions. These fragments would be going so fast that when they hit air molecules, they would trigger two or three more rounds of fusion.
 
After about 70 nanoseconds the ball would arrive at home plate. The batter wouldn’t even have seen the pitcher let go of the ball, since the light carrying that information would arrive at about the same time the ball would. Collisions with the air would have eaten the ball away almost completely, and it would now be a bullet-shaped cloud of expanding plasma (mainly carbon, oxygen, hydrogen, and nitrogen) ramming into the air and triggering more fusion as it went. The shell of x-rays would hit the batter first, and a handful of nanoseconds later the debris cloud would hit.
 
{"input":{"width":490,"photo":"30seconds4","row":"4981","table":"DOCUMENT"}}
 
When it would reach home plate, the center of the cloud would still be moving at an appreciable fraction of the speed of light. It would hit the bat first, but then the batter, plate, and catcher would all be scooped up and carried backward through the backstop as they disintegrated. The shell of x-rays and superheated plasma would expand outward and upward, swallowing the backstop, both teams, the stands, and the surrounding neighborhood—all in the first microsecond.
 
Suppose you’re watching from a hilltop outside the city. The first thing you would see would be a blinding light, far outshining the sun. This would gradually fade over the course of a few seconds, and a growing fireball would rise into a mushroom cloud. Then, with a great roar, the blast wave would arrive, tearing up trees and shredding houses.
 
Everything within roughly a mile of the park would be leveled, and a firestorm would engulf the surrounding city. The baseball diamond, now a sizable crater, would be centered a few hundred feet behind the former location of the backstop.
 
{"input":{"width":490,"photo":"explosion5","row":"4981","table":"DOCUMENT"}}
 
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.
 
**After I initially published this article, MIT physicist Hans Rinderknecht contacted me to say that he’d simulated this scenario on their lab’s computers. He found that early in the ball’s flight, most of the air molecules were actually moving too quickly to cause fusion, and would pass right through the ball, heating it more slowly and uniformly than my original article described.
 

Excerpt from What If? by Randall Munroe to be published by Houghton Mifflin Harcourt on September 2nd, 2014. Copyright © 2014 by xkcd Inc.. Used by permission of the author. All rights reserved.

Related Science Friday Link
 
About Randall Munroe

Randall Munroe, a former NASA roboticist, is the creator of the webcomic xkcd. The International Astronomical Union recently named an asteroid after him; asteroid 4942 Munroe is big enough to cause a mass extinction if it ever hits a planet like Earth.

The views expressed are those of the author and are not necessarily those of Science Friday.
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                                                 ^
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Code:
line 1: package tmpevalpackage;
line 2: sub doEval { 
line 3: 	my($parent);
line 4: 	
line 5: 	if($LayoutManager::url_resolved_values{'SEGMENT.nickname'}) {
line 6: 		$parent = $LayoutManager::url_resolved_values{'SEGMENT.nickname'};
line 7: 	}
line 8: 	elsif($LayoutManager::url_resolved_values{'VIDEO.nickname'}) {
line 9: 		$parent = $LayoutManager::url_resolved_values{'VIDEO.nickname'};
line 10: 	}
line 11: 	elsif($LayoutManager::url_resolved_values{'DOCUMENT.nickname'}) {
line 12: 		$parent = $LayoutManager::url_resolved_values{'DOCUMENT.nickname'}
line 13: 	}
line 14: 	
line 15: 	if($parent) {
line 16: 		my(@books) = &Database::SelectClause('BOOK',"parent = $parent");
line 17: 		if(!@books) {
line 18: 			$parent = '';
line 19: 		}
line 20: 	}
line 21: 	
line 22: 	if(!$parent) {
line 23: 		my(@sel) = &Database::SelectClause('GLOBAL','record all ""');
line 24: 		if(@sel) {
line 25: 			$parent = 'GLOBAL.' . $sel[0];
line 26: 		}
line 27: 			$main::ENV{'reading_header'} = "FEATURED READING";
line 28: 	}
line 29: 	
line 30: 	 = '';
line 31: 	
line 32: 	if($parent) {
line 33: 		my(@books) = &Database::SelectClause('BOOK',"parent = $parent");
line 34: 		0 = 0;
line 35: 		my $dots;
line 36: 		foreach(@books) {
line 37: 			my(%data);
line 38: 			&Database::GetRow($_,'BOOK',\%data);
line 39: 			my($status,$title,$author,$url,$image,$width,$height) = &SciFri::Schema::getAmazonItem($data{'isbn'});
line 40: 			if($data{'title'}) {
line 41: 				$title = $data{'title'};
line 42: 			}
line 43: 			if($data{'author'}) {
line 44: 				$author = $data{'author'};
line 45: 			}
line 46: 			if($status eq 'ok') {
line 47: 				 .= "<div class=\"box-2x1-item box-slide\" data-href=\"$url\">";
line 48: 				 .= "	<div class=\"box-2x1-item-photo\">";
line 49: 				 .= "		<div class=\"image-wrapper\" data-jsclass=\"imageWrapper\" data-align=\"right\">";
line 50: 				 .= "			<img src=\"$image\" data-width=\"$width\" data-height=\"$height\">";
line 51: 				 .= "		</div>";
line 52: 				 .= "	</div>";
line 53: 				 .= "	<h4>$title</h4>";
line 54: 				if($author) {
line 55: 					 .= "	<p>by $author</p>";
line 56: 				}
line 57: 				 .= "	<div class=\"box-2x1-more-button\"><a href=\"$url\"><img src=\"/images/v1/icon_text_more_white.png\" width=47 height=15 border=0></a></div>";
line 58: 				 .= "</div>";
line 59: 				++0;
line 60: 			}
line 61: 		}
line 62: 	}
line 63: 	if($parent eq "GLOBAL.1") { $main::ENV{'reading_header'} = "FEATURED READING"; }
line 64: 	else { $main::ENV{'reading_header'} = "RELATED READING"; }
line 65:  };
line 66: &doEval();
line 67: 1;

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