Here's his basic idea..."What if the Reaver spear couldn't possibly have made it through the forward windows of Serenity?" The rest of the article is here for your consideration. Feel free to follow the link above on over to the article at Slice of SciFi and add a comment if the moods strikes you. I'll give you the text here as well.
First Hill had to understand what modern spacecraft use. Certainly they have windows just as Captain Mal's Serenity does, but how thick are they and what protection do they provide from the harsh vacuum of space?
Hill is quick to point out that, within Earth orbit, space debris, no matter how small, still travels at approximately 9,000 meters per second. Which brought Hill to the following important scientific fact -- "Shuttles today are outfitted with shielding to prevent such disasters, and feature two-and-a-half-inch thick windows."
Next we need an example of what happens when a ship's window is damaged by debris in the vacuum of space. In this case, Hill selected an occasion wherein a paint fleck struck a window of a ship in flight to an international space station. The fleck caused damage that looked like the indentation of a "sort of miniaturized plate." Hill estimates the fleck caused "5,000 pounds per square inch impact, creating more than enough damage to warrant a window replacement." Yikes!
Now we need to estimate. So Hill eyeballed Wash's death scene repeatedly and concluded that "If Reavers shoot spears slow enough to be dodged (which they do), the spear that kills Wash can't be moving much faster than a Major League fast-ball, putting the upper limit on speed around 100 miles per hour (45 m/s).
This is orders of magnitude slower than the hypervelocity impacts that a shuttle deals with, but the spear is thousands of times more massive than a fleck of paint. Assuming it's fashioned out of a metal, and given its size, I'd guess it's around 100-200 pounds (45-90 kg)."
Our short translation for that is "Uh-oh." But Hill's not done yet. He adds, "Kinetic energy is easy enough to calculate, as is pressure. The kinetic energy of a moving object is one-half of its mass multiplied by the square of its velocity. This equation gives the Reaver spear a frightening 101,250 newtons of force at the low end. The pressure exerted by the spear is then equal to the force divided by the area it is acting on. Making the tip of the spear the size of a US quarter, the resulting pressure is a ludicrous 31,800 psi."
Conclusion? "This is over six times the force of the largest recorded impact to a space shuttle window, and almost four times the maximum pressure a shuttle window can take before deforming and failing."
Hill's ultimate conclusion almost isn't necessary, but, for the sake of finality, he revealed, "Wash didn't stand a chance."
As I sat pondering the science and math behind this analysis I thought, "I bet Joss Whedon could've told you that and saved you a bunch of work. Because he knows sci-fi fans will call you on something like this if they can." Wash never stood a chance.
A few seconds later another thought hit me. Remember the guy in Florida who got whacked out of his brain and started eating people's faces. The guy they said bath salts had turned into a zombie? Couldn't have been more wrong. He didn't become a zombie. He was still alive. He became a REAVER. There's a thought that will keep you up at night.