I saw an interesting mini-series, "To the ends of the Earth." They said when two becalmed ships are within?

Question

a mile of each other on a glassy sea, they will be drawn together "by the force of attraction of large objects." Did old sailors know of an experiment to prove Einstein's warped space or was this just a gimmick for the show? Is this true or BBC productions make believe.

Answer 1

This is NOT gravity -- the gravitation attraction of two large ships is less than the force of one sailor spitting off one of the ships.

But ... if there is the slightest current or waves or wind, and the direction is from one ship toward the other, then the downwind (or down-current) ship is in the "shadow" of the other. So it gets less wind (or current), so it moves slower, so the up-wind ship will move faster and catch the down-wind ship.

If the wind is 1/10 of a mile per hour, and the shadow effect is 10%, then the ships will be together in 100 hours = about 4 days.

Answer 2

Hmm, an interesting theory, but I would think impractical to test.

The force of attraction between any two objects is proportional to the product of their masses, divided by the square of the distance between their centers of mass:

F = GMm/r² where G is the Universal Constant of Gravitation

Let's consider two ships, each with a mass of one million kilograms (that's about 1103 tons), separated by one kilometer (0.621 mile) (the metric system is SO much easier to work with):

F = (6.672x10^-11 m³/kg-sec²)(10^6 kg)(10^6 kg)/(1000 m)²

F = 6.672 x 10^-5 kg-m/sec² = 6.672 x 10^-5 Newtons
F = 1.4999 x 10^-5 pounds = 0.000014999 pounds -force

The force of attraction is VERY small (15 one-millionths of a pound!). Those seas would have to remain glassy, and the ships utterly becalmed for a long, LONG time before they'd get close to each other.

Answer 3

Even just a mile apart, the force of gravitational attraction between the two would be very, very small... but, I suppose on an absolutely calm sea, with no current in the water, and no wind pushing either vessel, **eventually**... they would have to be drawn toward each other.

Answer 4

Hmm. Interesting.

You know, I'll bet that if the sailors knew this would happen--which it certainly does for moving ships--it might be one of those things that was only known empirically. I mean, Neandertals knew how to throw a spear accurately, but I'm pretty sure they never thought of y = Vo t - 1/2 g t^2.

That's my guess, anyway--even though your observation comes from a fictional novel series.

Answer 5

Wouldn't happen, because even a becalmed sea not totally without wind. You would need two ships under the worlds largest bell jar to test this.

Answer 6

Based on the novels by William Golding, 'To The Ends Of The Earth' is a three part miniseries, a fictional miniseries.

Answer 7

It would take a very long time, I'm sure. but even two marbles on a frictionless surface would be drawn to each other, eventually. Everything has a gravitational attraction.