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The Straight Dope


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We've all seen the sun's rays streaming down between clouds to brighten up patches of a lake or forest. Why do the rays projecting from the sun form a triangle with the ground, as if the sun were only a few hundred meters above the surface? We all know the rays are almost parallel. Is there some optical or atmospheric effect that causes this? --Peter Collins and Catherine Iphigenie, Montreal, Quebec

This is one of those explanations that's a hell of a lot easier to show than tell, but unfortunately we haven't got the video version of the Straight Dope hooked up yet. Our next best bet is an intuitive leap using the following magical key phrases: Railroad track illusion. Foreshortening. Lack of depth perception. Get it? Well, it was worth a try. Buckle down and we'll do it the hard way.

When you see this illusion it looks as though the sun's rays are striking the earth at a right angle--that is, as if the sun were directly above the illuminated patch of earth. But it's not. (You never notice this at noon, do you?) The rays are actually striking the ground at a very shallow angle. The apparently close-to-equilateral triangle you see is actually an extremely elongated triangle, at one vertex of which is the sun, 90-odd million miles away. You're looking down the triangle lengthwise, but you can't tell that because there aren't any good depth cues in the sky. Think of the sides of the triangle as a sort of railroad track extending from the earth to the sun and you'll get a better picture of what's really going on. The sides of the triangle appear to converge a few hundred meters above the ground for the same reason the rails of a train track appear to converge at the horizon. In both cases they . . .

OK, I can see this isn't working. One last time. Take an index card and draw a tall skinny triangle on it. Now close one eye, hold the card edgewise up to the other eye, and sight down the length of the triangle from base to tip. The long skinny triangle has been miraculously foreshortened into a squat, almost equilateral triangle, right? (Of course it has. Don't smart off to your Uncle Cecil.) Same thing happens with the rays of the sun. Humor me and say you understand.

Is there any major religion that believes there is no life after death or any continuation or reincarnation whatsoever? --Azbug, Berkeley, California

Are you kidding? Absolutely everybody, including atheists, believes in life after death. Eleanor Roosevelt died and you're still alive, yes? I rest my case. The question is not whether there is "any continuation or reincarnation [of life] whatsoever" but whether (1) you continue to enjoy some sort of personal existence after death, and (2) whether there is a spiritual or immaterial realm that transcends death. On the latter point every religion I have ever heard of argues for the affirmative--else why have a religion?--but there is disagreement on point #1.

Buddhists, strictly speaking, do not believe in an immortal individual soul, and in fact much of Buddhist teaching is aimed at the extinction of personal desire. Other Eastern religions don't take it that far but do say the proper aim of individual souls is to merge anonymously with the Great Font of Existence. Old Testament Jews did not have a fully worked-out idea of the afterlife until late in the game, and even today one may argue that personal salvation in Judaism is secondary to the deliverance of the Jewish people as a whole. Apparently it was the Egyptians who first popularized the idea of a personal postmortem paradise, an idea since adopted by Christians and Muslims. But it's not true, as your question seems to suggest, that the chief appeal of all religions is the chance to cheat Mr. Death.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.

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