Happy Back to the Future Day! That’s right, Doc Brown, Marty McFly and Jennifer Parker arrive today. Residents of Hill Valley beware!

And what better day than October 21, 2015 to contemplate the space-time continuum. No, not the mathematical model that joins space and time into a single idea, representing space as three-dimensional and time as the elusive “fourth dimension,” and making time travel theoretically possible. But a more practically useful space-time continuum, for which Continue reading →