You should be serious. It could well be that the genes responsible for the long legs of a giraffe are integral to its long neck. Giraffes drink infrequently, but a dearth fresh foliage to eat probably increases that need. Their stance to drink is already awkward, getting down on their knees (elbows) would leave them even more vulnerable to predators. Their height may be limited by their ability to drink.
I’m actually familiar with tides, as was the Italian Galileo. I know, as he and others did, that they vary a great deal in real life in real oceans. And that these complexities are not easy to explain in detail.
For another view of tides, let us consider Kepler, since he was one of the greatest scientists who ever lived, and a classic edifying example of abandoning a pet idea when faced with evidence; and his explanation was not greatly different from older ones, and it agrees in some ways with the facts as now known.
By Kepler’s theory that the Moon exercises an influence over the waters, “there is one high tide a day, it’s when the Moon is directly overhead, and it’s always about the same height and behaves the same everywhere.” I’ve highlighted the major predictive differences between the two theories; please correct any errors. The balance does not seem to be strongly in Kepler’s favor.
It appears (according to such scholars as I’ve seen commenting) that no one ever made a good account of two tides a day until Newton brought the full force of modern dynamics to the problem. Galileo at least made a try at an explanation, and it’s on the right track for many real tidal phenomena: to wit, the size and shape of basins.
But that’s supposed to make two tides a day? Crazy! Except, umm, maybe you should ask an oceanographer who works with tides what it is that causes the one tide a day at a point on the coast of Vietnam. The answer will be the various resonances of the ocean in that area, combined, of course, with this being half the frequency of the tides in general. Galileo would probably not be shocked at this.
While we’re up, let’s ask the oceanographer why there are negligible tides on many islands in the middle of oceans. Or why the tides are so small halfway up the Adriatic when they’re large at Venice. Heck, for that one you don’t need an oceanographer; just ask Galileo, who explained it explicitly and correctly. (“Correctly” includes “by good reasoning”: no credit for accidents.) Would he then have had trouble explaining the tides at the islands? I doubt it.
The bit about when the one high tide occurs isn’t obvious, so let me expand a bit. We might go to Great Britain, a place where they really know the tides, and ask people in various places when the high tide is on a given date, and how well it agrees with the position of the Moon. You will find that their answers vary by a matter of hours. This is not explained by difference in longitude, in that England is rather less than 15 degrees (one hour) wide. You know what the explanation is.
In fact, and perhaps you know this, Galileo knew magnets well, heaping praise on Gilbert for his ground-breaking empirical investigation of them. Let us by all means call him a fool or a liar, then, along with nearly every philosopher of Newton’s time two generations later, who hated gravitational “action at a distance” as a seeming absurdity. It had to be conceded, though, that the thing worked, and nothing else did. But serious thinkers still disliked the idea, as did their successors until 1915.
Galileo got the motive force of the tides wrong. let us never forget that!! Not that we could. Arguably he ought not to have done it. But his ideas gave potential explanations for some anomalies, arguably worth further investigation, that other theories don’t have at all. To call it his ideas a bunch of hacks is to ignore what he said (along with masses of empirical data) in order to score points.
I think that one may be a misunderstanding / misinterpretation of an old but never-repealed Parisian law against women wearing trousers (as opposed to dresses / skirts).
I thought it was a reference to this.
Also referenced in Jonathan Coulton’s Over There.
ed malin said:
You can pick your reference point as any arbitrary place in spacetime. The problem is how to identify this arbitrary point from any other arbitrary point. Until we map out all of spacetime with a coordinate grid system and a convention for aligning the grid, we are stuck referring to objects within spacetime as our points of reference. As Chronos said, you could pick a point like the center of mass of the Earth and Saturn (okay, he said around another star), but you still have to know about Earth and Saturn to find that point.
OK guys, how about these two possibly dumb questions:
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Can gravity diminish to the point where it has no effect on some known particle? i.e. won’t accelerate it.
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If a force is delivered to matter in quanta, is there a period of time between quanta where the force is not measurable. i.e. is acceleration measured as a series of chunks?
btw: i started out wondering if a baseball could actually travel in a ‘straight line’. look where that has taken me.
Our best current understanding of gravity is that it continually and smoothly trails off, but never quite reaches zero. However, we know that our current understanding of gravity is incomplete, and it’s quite plausible that it does in fact occur in discreet quanta. But if so, the quanta are small enough that we’ve never been able to detect evidence of them. And it may well be (for all we know) that even with a quantum theory of gravity, it’d still be smooth somehow.
Do we know enough about this regarding any force (we excluding me, because I defenitely don’t know)? Is there a real granularity to the universe that is known? You seem to be saying ‘not with gravity in a way we can prove’.
We do understand electromagnetism about as well as it’s possible to understand anything. At least, the theory agrees with the observations to an insane degree of precision, and there aren’t any inconsistencies in the theory, or other specific reasons to believe it’s incomplete. And the answer to your question is, in layman’s terms, that there is “granularity” of a sort, but that it shows up in much more complicated ways than you make out.
Thanks, sounds like the time to go back and try to learn something useful about quantum physics. The whole ‘understanding’ thing is going on in another thread. I wonder if you have an opinion on how close we are to understanding a finite set of rules that defines the universe, if there is such a set of rules. Based on the reports of others, it sounds like we could be getting close, unless we’ve missed something big entirely, which would certainly seem possible. Are we nearing the ‘end of physics’, or are we as close as we were to the ‘end of history’ about 20 years ago? (and did anyone believe that end of history thing?)
There are some big things entirely that we know for sure we’ve missed, quantum gravity being chief among them. But even if we do get that one licked (which I don’t expect will happen in my lifetime), I’m confident that we’ll just go on discovering other mysteries.
A reasonable point of view, and one which would make the future more interesting.