Shaft!

[mmcirvin]

This synopsis of general relativity (in honor of the Gravity Probe B satellite) is pretty good, but it contains a small factual error: The vertical shaft in which the Pound-Rebka gravitational redshift experiment was performed was not, as commonly believed, an elevator shaft. It was a shaft that was built into the Jefferson Physical Laboratory in the 19th century to do free-fall experiments. In a sense that feature of the building was always for studying gravity. There were elevators built into the building later, but they were elsewhere.

I know this because my desk was in an office a few meters away from the famous shaft for several years (and before that, it was in an office a few meters away from Bob Pound).

Once (as I mentioned in a comment before) somebody I had known as an undergraduate came to visit (he was filling in as a substitute French-horn player in a concert at Memorial Hall) and I mentioned that the building was the first in the world at which the difference in the rate of the passage of time at the top and bottom had been measured (this is one theatrical way of talking about gravitational redshift/blueshift). He looked at me like I was crazy and said "That's ridiculous. Time is a constant." I couldn't convince him otherwise. How slowly they learn.

Comments

[dumplechan.livejournal.com]

That shaft is one bad...

[ THE OBVIOUS BAG ENTERS, CONSUMES SWT, AND PERFORMS A SERIES OF BIRDCALLS FOR THE AUDIENCES'S BEMUSED EDIFICATION ]