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Archived Post

This post is archived from my Posterous blog, which shut down in 2012. Some posts have been edited slightly to fix typographical errors, correctly represent the gender of some individuals, and remove unnecessarily-gendered language. You can view the full archive here.

A three panel comic. Panel one shows Doc and Marty from Back to the Future. Doc is saying the time machine will appear in the same place one minute in the future. In panel two the time machine disappears with fire tire tracks. In the final panel the time machine is floatin in space some distance from the earth.

Same place, different time.

A lot happens in one minute. The Earth moves about 11,000 km in its path around the sun. Meanwhile, the sun (and all the rest of the solar system) moves about 13,000 km in its path around the center of the galaxy. Note that the Earth itself is about 13,000 km in diameter.

The whole Milky Way galaxy also “moves” in the direction of the constellation Leo, but this is due to the expansion of the universe itself, so it would be fair to say that any “same place” in the universe also moves with it, making this movement irrelevant.

So, if a time machine jumps forward one minute in time, and stays “in the same place” the Earth will have moved roughly one Earth-diameter away during that time.

One final note: 88 miles per hour is about 10,000 miles an hour too slow to maintain orbit at 13,000 km, so the time machine will probably come back pretty soon.

On the bright side, Einstein tells us everything is relative so I guess there really is no same place anyway.