Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.
The question is: If you hang two plumb bobs, say 50 feet apart are the
I would say they are as close to parallel as one would care for them to be.
If you want to get technical, they are not exactly parallel due to the
curvature of the earth. One would assume that the bottom of the plumb bob
is pointing at the exact centre of the earth due to gravity and since we're
on a ball, they wouldn't be exactly parallel. At 50 feet apart, the
difference wouldn't be enough to care about.
I was in HS when they built the Verrazano Bridge in NY. I remember one
of my teachers explaining that the uprights had to be 6" out of parallel
due to the curvature of the earth. I don't know if the number is
accurate, but that is what I recall (after forty years or so).
Let's do some quick math.
The towers are about 700 feet tall, and the Earth's radius is about 4000
miles. 700 feet / 4000 miles is about 1 part in 30,000.
Since arc length is proportional to radius, the tops of the towers are 1
part in 30,000 further apart from each other than their bases. The towers
are about a mile (call it 5000 feet) apart, so the tops are about 5000 /
30,000, or 1/6 of a foot further apart than the tops. Call it two inches.
Now, let's got to the video tape. Wikipedia says:
Theoretically, no, but I doubt if you could measure the difference if
they were just 50 feet apart. If the 2 bobs were, say, a couple
thousand miles apart, they'd both be pointing towards the center of
the earth, so they definitely wouldn't be parallel.
Isn't that the principle that led to the first calculations of the
earth's diameter? Some guy looking down wells... OK, google tells me
it was Eratosthenes, in Alexandria.
Ok then... In recent news;
In a recent study, mathematician George Sparling of the University of
Pittsburgh examines a fundamental question pondered since the time of
Pythagoras, and still vexing scientists today: what is the nature of
space and time? After analyzing different perspectives, Sparling offers
an alternative idea: space-time may have six dimensions, with the extra
two being time-like.
So if I turn a six dimensional bowl on my quantum lathe, primarily
taking advantage of the additional time-like dimensions, how long do I
have to work the finish in before it dries?
A1) No, since each will hang toward the center of the earth (ignoring
gravitational pulls of other less massive or more distant bodies).
A2) Yes, if the correctness of the answer is going to be determined by
empirical methods using measurement tools available to the average
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