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...
Mm, I was definitely thinking that the source radiates all around, and then you can grab that and focus it after; I have no idea how lasers work, but I'll take your word for it gladly.
The second question, of course, that then arises: does that answer apply in a more primitive society where it may be physically true but no one knows that, because they only have candles and lamps and no lasers at all; can a phrase be tautological in context, where it's not in physics...?
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 06:09 pm (UTC)The second question, of course, that then arises: does that answer apply in a more primitive society where it may be physically true but no one knows that, because they only have candles and lamps and no lasers at all; can a phrase be tautological in context, where it's not in physics...?
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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)