An exercise for the reader in spacetime

Here’s the problem with astronomical/cosmological measurements of time and space:

Say you’re at home plate on a baseball field. The left fielder wings you the ball two seconds ago from four hundred feet away. WHILE THE BALL IS IN TRANSIT someone stretches the field another five feet and adds another second of time to what’s elapsing. Screw how many feet per second is that ball traveling. What time was it when it was thrown and what time will it have been by the time you catch it? How far away was the outfielder when he threw it and how far away will he have been by the time you catch it?

How about if you measure it again ten seconds from now, judging by echoes of the grunt from the outfielder throwing it and echoes of the ball hitting your glove when you caught it? (Assuming the field stretches at a constant rate of five feet and one extra second per two seconds, of course.)

Now, how long ago was the hypothetical big bang? How long ago will it have been if you measure it again thirty seconds from now?

You’re welcome.



Big ups to the English language for being able to handle those verb tenses as well as it did. That’s some tricky shit.


November 24, 2009 · by xalieri · Posted in Everything Else  


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