Wednesday July 23, 2003
Note: If you are mathematically inclined, you may be familiar with classical word problems in algebra and calculus in which the correct answer is "insufficient data." Many readers of Schlock Mercenary have been looking at the puzzle suggested by the incoming light-sail, since there is insufficient data to determine things like the mass or speed of the sail-ship. These clever readers have wondered just how much real math has been done by the author.

The answer, of course, is "as little as possible."

Fortunately, with the data provided in today's strip, readers need only assume the size and luminousity of the star to work things out for themselves. Unfortunately, they may also have enough motivation to do this math, since the author is going to offer sketches to the first five answers deemed correct by his panel of judges.

Assume that the star is identical to Sol - it weighs 1.9 x1030 kilograms, and puts out 3.8 x1026 joules/sec. At the current rate of deceleration, the sail-ship will approach to within 90 million miles of the star in exactly eight months. The sail is 102,000 kilometers in diameter, and only an insignificant portion of that surface is in shadow. When it crosses the center of the system (assume a mercurially-close passage), the sail-ship will have exceeded stellar escape velocity by a factor of three.

Given this information, you ought to be able to determine the current velocity and mass of the sail-ship, as well as its current distance from the star.

You also ought to be able to resist the temptation to spend this much time on math. After all, the author did, and you're certainly a better person than he is, right?

Book 3: Under New Management
Part III: Board of Accidental Tourism


Jevee Ceeta:What's the word on this light-sail we've found, captain?
Tagon:Ennesby has been tracking it for the past six hours. It's going to pass right through this system in about eight months, and then sail back out into interstellar space. It's no threat to us.
Sign:Not a step
Ennesby:Update. It's either going to end up back in interstellar space, or it's going to plow into the sun.
Tagon:I guess that's one danger of sailing directly into the solar wind.
Ennesby:Tacky, sir.