If you haven’t read Fafblog, go, then come back later. The post will still be around.
So Giblets and Fafnir talk estacology, and how they plan to transcend this whole spacetime thing.
Funny they mention that, as last week, Jeff Bone pointed out a physics paper about closed-space-like causality curves. The authors call these things ‘jinni’, but they sound like the plot to Back to the Future.
Aha!
- Michael J. Fox played Marty McFly, the kid on the closed-space-like curve.
- But he also played Alex P. Keaton, the Reganista teenager on Family Ties.
- The Medium Lobster is a closed-space-like curve, and a conservative.
We can draw one conclusion:
While Brad DeLong and Gary Farber may speculate on the identity of Fafnir, it’s obvious that The Medium Lobster is Michael J. Fox.
Update: Jeff Bone writes in with a clarification, so that the silliness is rigorous:
At the risk of being needlessly pedantic, I thought I might point out that, AFAICT, your use of the term “spacelike” in the Medium Lobster post is in fact subtly incorrect. (Spacelike, timelike, what’s the diff? ;-) While you are correct that the use of “spacelike” usually implies faster-than-light and hence time-retrograde motion when used to describe motion itself, the (geometric) curves in question are indeed called “timelike” curves. This clearly confuses an already confusing situation, but is the common practice (cf. the paper in question.)
The motion of any particle along such a timelike curve is indeed spacelike for parts of its trip; its light cone precesses and the metric tensor takes on a negative value. But the curve itself is said to be timelike, perhaps in order to convey the idea that the overall curvature is indeed “through time.” Motion - spacelike. Curvature - timelike. Apparently.
A closed “spacelike” curve would then presumably be a path which merely closes itself in space, without the tangent of motion ever taking a negative metric tensor value. I.e., my commute to work everyday (at least when seen from my house as a rest frame. ;-)
