chicks dig unix

Kevin mused the following on his LiveJournal:

“A Jedi typically defends themselves against blaster fire by using their lightsabre to deflect the shots. If you consider a random distribution over time of blaster shots, and allow the jedi to move arbitrarily fast, this works. However! A lightsabre is fairly close to being a straight line, and therefore, if the blaster shots are simultaneous, only shots colinear on a single line are deflectable at any one time.

So! if you make a blaster with three barrels, arranged triangularly, and they’re spread out a little to get around the small frontal area of the lightsabre, and the three barrels shoot simultaneously, you’re guaranteed at least one hit, even if the Jedi blocks the other two.

Time to purge the Jedi scum from the universe methinks”

I work with several hardcore Star Wards nerds and as such Star Wars is a very common topic of conversation in the office, much to the chargin of the QA engineer who sits near the developers and could care less. They’re also nerds of electronic engineering and other disciplines, so I figure they’ll get a kick out of it and I send it around. First in is a reply from Star Wars Nerd Numero Uno:

“You’re not guaranteed at least one hit.
First, the Jedi could swipe the lightsabre at an angle to the perpendicular plane of the trajectory of the shots thereby deflecting two colinear and, allowing for a small amount of travel along its trajectory, the third.
Second, the Jedi can use the lightsabre with one hand, and with the other hand, use Force Push to deflect miscellaneous shots.
Third, the Jedi can use Force Speed to simply step out of the way.”

And then, just before lunch, the CTO follows up with:

“Good theory but needs more rigour:

If you assume that a touch of the sabre is sufficient to deflect a blaster shot. Then, given:
- Sjedi is the linear speed a Jedi moves the sabre (neglecting relativistic effects of speed of light limits)
- Dsabre is the sabre width
- Sblaster is the speed of a blaster shot
- Dblaster is the distance between blaster shots

Then the distance travelled by a blaster shot in time T is: Sblaster*T, which must be greater than Dsabre to kill the Jedi, i.e.

Sblaster * T > Dsabre

We also know that if the Jedi moves between two successive blaster shots in time T:

Sjedi = Dblaster/T

which implies

Sblaster * Dblaster / Sjedi > Dsabre.

In other words, to kill the Jedi and assuming all sabres are made equally, you need to either increase the blaster speed, or increase the distance between blasts, or slow down the Jedi!”

(Can you tell he’s currently writing a book for Wiley and on occasion co-authors IETF Drafts?)

Kevin wakes up and fires back with this retort:

Assuming that after passing the sabre the bolt has about a quarter of a meter to travel, and assuming that blasters aren’t completely shit and have muzzle velocities comparable to a decent modern gun’s (say 1000m/s), the bolt is gonna take 1 or 2 ten thousandths of a second to travel the rest of the way to the jedi’s body. The sabre has to move even faster, as it needs to move diagonally in the same time.

As for Force push (presumably this is from some video game or other), in the movies they never use telekinesis on blaster shots, only larger items, which makes sense when you consider the speeds and reaction times involved. And as for Force Speed, assuming a shot from 10m away and the speed above, it takes 100th of a second to reach the Jedi. If the Jedi moves a metre to avoid it you’re talking about an instantaneous 10g acceleration, which will probably result in them needing to use Force Tylenol and maybe Force Nice Cup Of Tea And A Sit Down before continuing the fight.

The whole using a lightsabre to deflect shots thing relies on a heightened state of awareness to process the visual cues and predict where a gun is actually pointing, coupled with precision in movement and fast enough reflexes to use this information. Think Miyamato Musashi in space. It’s not one of the more obviously magical things they do. If you accept this, and you’re obviously free not to, then this technique becomes subject to physical (and physiological) limitations - there’s only so fast we can move, even if we can expand our perceptions to the point where we have exact knowledge of our immediate surroundings. This is supported by all that “stretch out with your feelings” and “sense the target droid” bollix. If it were another “magical” skill like telekinesis, it would be a question of learning that and just invoking it to deflect anything in a wide area, effectively using it like a shield. And if that were possible, you’d expect to see things like Force Push being used as a 360-degree stun weapon by creating a compression wave in the air around the Jedi.

But after this the energy is gone and here the to and fro ends. A fun distraction while it lasted. I’ve saved the discussion here for posterity.