Riding Sunlight to Jupiter

1.8 trillion furlongs per fortnight...

I would have used meters, but the French Revolution's inability to implement decimal time in 1794 has turned me off to SI Units. It just seems the height of hypocrisy to claim that base 10 should replace all systems and then use base 60 time in that same system.

Really, if you think about it, the English system is much more congruent with base 60 time than the SI system. Perhaps after Europe and the rest of the world adopt decimal time we Americans will be ready to give up our antiquated system, but to trade one flawed system for another seems pretty pointless.

So since Americans think in miles and that's my nationality, I decided to present the data that way. I could pedantically quote meters and meters/second, but then the information becomes unnecessarily abstract and that defeats my goal of conveying the vastness of space.

I have never heard a doctor tell a nurse " give the patent 5/32 of a pint of this". If this occurred then the already disease ridden hospitals would be even more of a death trap.

Thanks, Roger. That was enlightening. I've always thought of light traveling amazingly fast, but seeing the planets pass by, it doesn't seem that fast after all. Of course, to a photon, everything happens simultaneously, relativistically. It might never even notice the universe existed.

Yeah, I was always fascinated by that aspect of relativity. To be precise, it is unclear whether it is ok to extrapolate time dilation like that, but it is also not clear that you cannot. I've certainly have tried to visualize what it would be like for light if it didn't experience time. What I've come up with is everything is in the same spot and a jumbled combination. Makes me appreciate time. Also has made me wonder if that could be behind the "action at a distance" of entanglement. All baseless conjecture on my part, but fun!

I've read that "everything moves at velocity c through spacetime". It's a kind of funny idea, since velocity is displacement per unit time, and time is part of the "displacement". But I guess that is OK. (Actually, I think it's called four-velocity).

I found this explanation of Special Relativity on the internet one time, but haven't located it since:

If you're moving with respect to me, your coordinate system is slightly askew with respect to mine, so our relative velocity is the vector difference between two vectors that are almost parallel. (I visualize two jet planes flying almost parallel and drifting slowly apart.) If the relative velocity is great enough, the coordinates will be far enough from parallel that your distance will seem shorter to me and your "time" will seem to be foreshortened (pass slower). By symmetry, you will see the same effect in my coordinate system from your viewpoint.

Travelling at velocity c through space, a photon's coordinate system in spacetime is rotated a full 90 degrees, so that its "velocity" c is completely in some spatial direction and none at all in the time direction.