Okay, so for those of you who have never heard of it, let me give you some background. Newton was 100% wrong. That's part 1. That apple falling his head turned out to really be a lump on his head for nothing. What Einstein has said is that time and distance are connected at the hip. Like that irritating couple in middle school. And also that everything is completely relative, hence the clever title.
So, as theory has it, if you travel really fast... like really fast (think Apollo Ohno variety)... then your time and distance you travel will be different than someone who's standing still. And the faster you go the shorter the distance is to you... there are plenty of jokes about how according to special relatively a bus going really fast will turn into the short bus. Get it. Special relativity?! RIGHT?! It kinda works like this (from this site):
Anyway, this theory is that if the Millennium Falcon actually travels fast enough it can theoretically shorten the distance, thus making the parsec line make perfect sense. "Fast enough for you, Old man. It's only the ship that traveled so fast that to me the distance was shortened by 6 parsecs, of course to you the distance was the same, because it's all relative... you know how it is."
So, according to Special Relativity Han Solo wasn't lying and George Lucas wasn't an idiot writing that sentence!
BUT HERE'S THE PROBLEM WITH THIS THEORY!
If we're going to believe this, then we have to believe that the Star Wars definitely existed in our universe, thus following our physical laws. So if that's the case, then dig this: 12 parsecs is about 39 lightyears. So if Han Solo was traveling at the speed of light this run would take him about 40 years, and Harrison Ford is not that old in the movie.
BUT WAIT! Han says that the ship can travel .5 past light speed. Okay. EVEN if we are to accept that the Millennium Falcon could travel 1.5 times the speed of light (not possible) through the concept of hyperspace (not plausible) then it's still 26 years.
And sure, he won't age that much because he's following the laws of special relativity, but he'll still age... and if he travels this fucking much and claims to do the Kessel Run so much than he has done it numerous times... and really, if he were that old than the love story wouldn't work. So I'm not buying this either.
Also, I have reason to believe when he says .5 past the speed of light it actually means that he's going .75 the speed of light because of time dilation numbers... but I won't go into this here.