RAY: You are kidnapped and unceremoniously dumped on a deserted island in the Pacific. This island basically is 10 miles long and about a hundred yards wide, and it's completely covered with grass and palm trees. And your captors have been nice enough to give you a few things to assist you in surviving. They've given you a supply of water, a life-size poster of Ginger Grant, a flashlight, a box of matches and a blankie. So, the first day, you walk around the island, and you notice that you've got no chance of escape because the island is sheer drop-off all around, 500 feet onto sharp rocks into shark-infested waters. So, there is no escape from this island, and you go to sleep that first night under your blankie, and you're awakened the next morning by the sound of thunder and the bright flash of lightning.
TOM: Oh-oh. I'm not going to like this.
RAY: I don't think so. And you realize that lightning has struck the far end of the island. You're approximately in the middle, let's say, so five miles away from you, lightning has struck and has set the grass and palm trees on fire. And as luck would have it, there's a breeze blowing from the fire toward you. So, it's pushing the flame in your direction. And you can imagine that everything on the island is going to be toasted—including you, unless you think quick. And the question is: How do you save your sorry butt until your wife can pay off the ransom?
RAY: All of us remember from our high school or junior high school physics that the Moon has a fraction of the Earth's gravity. In fact, we were all told that it's a sixth the gravity of the Earth. When those NASA guys faked the landing on the Moon, they were very careful to show the astronauts bounding from one spot to another, like they were kangaroos.
TOM: How DID they fake it?
RAY: Springs. Invisible wires. You've never seen Peter Pan? Anyway… for example, if you had a bathroom scale, and you put your 600-pound...
TOM: mother-in-law?
RAY: I knew you were going say that! If you put your 600-pound Bengal tiger on this bathroom scale, and then transport the tiger and the bathroom scale to the Moon, the Bengal tiger (or the mother-in-law), would weigh 100 pounds. You with me?
TOM: I'm with you.
RAY: Here's the question. Is there anything you can think of that, if measured in the same way, would weigh more on the Moon than it does on the Earth? Now, I have an answer in mind, but there may be more than one right answer.
A Matter of Gravity
TOM: My answer was a helium balloon.
RAY: There you go. Any balloon with lighter-than-air gas, such as helium or hydrogen, would work for an answer. Because on the Earth it wouldn't weigh anything on the scale, right? In fact if you were standing on the scale and holding a big enough helium balloon it could make you weigh nothing. If you tried to put it on the scale it wouldn't register because it would float away. But on the moon, because there is no atmosphere, in addition to being not much gravity, there's nothing for the balloon to float on. Therefore, if it doesn't explode, it'll sit on the scale and it'll actually weigh something, whereas on the earth it doesn't weigh anything.
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The Principle of Least Interest: He who cares least about a relationship, controls it.
