Umm - thinks - is it possible to radiate in one direction only, or only in a few? Or is 'radiate in all directions' an absolute tautology, in all circumstances? Answer on one side of the interweb only...
You can read the Wikipedia article about lasers if you really want to know. But the fact that they send out all their light in exactly the same direction is one of the major things that make them so useful.
And since a tautology is a semantic thing, it doesn't have to care about physics. But I suspect that the lamp that shines in one direction only is an old enough concept (all it takes is a flame and a box with only one opening, after all) that "radiate" doesn't necessarily mean that stuff is being sent out in all directions. Far from sure, though.
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Date: 2006-07-06 06:18 pm (UTC)And since a tautology is a semantic thing, it doesn't have to care about physics. But I suspect that the lamp that shines in one direction only is an old enough concept (all it takes is a flame and a box with only one opening, after all) that "radiate" doesn't necessarily mean that stuff is being sent out in all directions. Far from sure, though.
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Date: 2006-07-06 09:52 pm (UTC)