UPDATE: Hints added at the end.
That Mythbusters discussion and Ricki's post about it brought up a great question posed to my Physics class in college, and as I leave this veil of tears for the long trek home tonight, I will pose it to you.
It applies a little more to physics than to other disciplines but it is an interesting little poser:
What is the difference between a "law", a "theory", and an "equation"?
First update: Add the word "model" to the mix.
And yes, it's not a perfect explanation of the terms but it definitely is an interesting way to think about them. Second update: Don't overthink it. It's not a "real" definition.
FIRST HINT:
Newton's Law of Gravitation
Einstein's Theory of Relativity
Schroedinger's Wave Equation
The Big Bang Model
SECOND HINT: I may not have asked the right question ;)
Think about it, but not TOO hard.
Posted by Ken S at February 21, 2008 05:41 PM | TrackBack (0) |Well, about "theory," the most clever thing I can say is "You keep using that word. I do not think it means what you think it means.".
In other words: in common parlance, "theory" is just one step above "nonscientific wild-ass guess." In science, it's something more like "very well supported body of knowledge about a single topic."
Equation I always think of as a brief symbolic or mathematical explanation of some natural phenomenon.
And law...well, I don't deal with physics-type "law" much in biology, but there are certain things given the name "law" (like Shelford's Law) which seem to be "we've tested these a whole buttload of times and can't seem to violate them" or the Laws of Thermodynamics, which, internet purveyors of free-energy devices notwithstanding, seem to be "the way the Universe works" and can't be violated.
I think an equation is a statement of the relationship between values. Like PV=nRT. Keep the number of moles and the temperature constant, if volume goes up then pressure goes down, and so forth.
A theory is an overarching explanation of observations, which one may test by using it to predict the outcome of experiments that haven't been done yet. The better it predicts those outcomes, the more confidence one has in one's theory. A theory may be tweaked if necessary, when new observations come in, or thrown out altogether, even if one really likes it. I suspect phlogiston's departure from the realm of accepted theories really bummed some people out.
Can't state a definition for law that's any different from what Ricki said.
Posted by: Laura(southernxyl) at February 21, 2008 07:19 PMMan. I still miss phlogiston.
Excellent link, Ricki. I just love this part (my emphasis added):
Not only will Florida's students learn about evolution; they'll also learn that the scientific definition of a theory is different from the everyday definition, referring not to wild-eyed speculation but to a vast body of observation and testing that confirms a hypothesis so strongly that it might as well be considered fact.That may be a little strong, given the two different meanings of the word evolution:
The first meaning is the simple fact of evolution: it is observed that, at different times in history, entirely different populations of life have inhabited the earth and that subsequent forms tend look a hell of a lot like the ones immediately before (or even continuing to live concurrently). This is so well documented that it is "fact" the same way the "all objects denser than air fall when dropped" is fact -.the evidence is overwhelming.but it's a nice and pithy post nonetheless. Posted by: Ken S, Fifth String on the Banjo of Life at February 21, 2008 07:39 PM
Um... you mean "vale of tears." You can't exit a veil. [/PEDANT]
Posted by: Andrea Harris at February 21, 2008 08:57 PMI was being nice, Andrea.
(And also wondering if veil/vale was a subtle pun and I'd look stupid if I said anything.)
(Now you can look stupid too if it is.)
Posted by: Laura(southernxyl) at February 22, 2008 05:02 AMYou can use a veil to mop up tears, or tear a hole in a veil (top to bottom, if you're really talented) - was that the pun Ken was looking for?
Posted by: nightfly at February 22, 2008 06:03 AMIt... it... it's a subtle pun. It is, I tell you.
Yeah, that's the ticket.
Posted by: Ken S, Fifth String on the Banjo of Life at February 22, 2008 06:26 AMBeing totally flip here, but in my world as an ecologist, a "model" is something that the math-heads (not to be confused with meth-heads) who never leave their offices or labs make as Theories of Everything Important In the World, and that those of us who actually collect data in the field, break. And then the math-heads tell us that our data were "too messy." Or that we used the math wrong. Or something, something to preserve their precious model.
Models are tentative explanations for phenomena that sometimes work but mostly don't. Or at least that's my experience. Whenever I present a model of something in class, I spend an awful lot of time talking about how the model tends to be violated in the field. Or how it doesn't take into account something that actually happens to be important in the field, like herbivory.
Posted by: ricki at February 22, 2008 07:17 AMSpot on, ricki! Models are generally incomplete descriptions of the real McCoy. Computer models are quite prone to considerable inaccuracies, if not outright failure. Physical models are less prone, have to be approached with caution, but tend to be more reliable.
Usually, the best models concern easily and clearly defined systems, especially if they can be isolated from other influences. Alas, many people take model results as gospel, while ignoring the obvious flaws (and this is just not limited to global warming fanatics; I've seen this very phenomenon amongst professional engineers).
Possibly the best example I can offer of what I term "The Computer Model Oracle Syndrome" was the 1993 flooding in the midwest. I haven't been able to confirm this particular story, but it's a fact that the Corps of Engineers once had a scale physical model of the entire Mississippi River basin in Vicksburg, MS (some images of the "Mississippi Basin Model" are here). It's inactive now, superseded by computer models.
As the story goes, the model was mothballed in the late 1980s. When the 1993 floods hit, though, the then-existing computer models simply weren't working right; their forecasts weren't anywhere near being correct. So they had to re-activate the physical model in a hurry, including bringing a couple of retired employees back on board. The physical model produced better forecasts.
The model is inactive now (the computer models having been suitably tweaked, one would hope), but this is a good example of how models have to be taken with a large grain of salt.
Posted by: The_Real_JeffS at February 22, 2008 08:06 AMYou can use a veil to mop up tears, or tear a hole in a veil (top to bottom, if you're really talented)
My now-ex-wife burned a hole in her veil at our wedding, blowing out the unity candle. Not a good omen...
Posted by: Joel, president of Catholics for Xenu at February 22, 2008 08:58 AMOoh. Lacey headgear and open flames are not a good combination.
Posted by: Ken S, Fifth String on the Banjo of Life at February 22, 2008 09:06 AMNeither are open flames and beards.
Posted by: Ken S, Fifth String on the Banjo of Life at February 22, 2008 09:08 AMNo one brought up the Salome-removing-her-veils analogy (in other words, "leaving" them -- and in two ways, she's "exiting" the veils and also leaving them lying around on the floor...) Score!
Posted by: Andrea Harris at February 22, 2008 09:16 AMI am an accountant so...
A "law" is some linguistical nightmare of complexity that makes no sense to anyone, especially the congress that drafted it, such that we need volumes of regulations, rulings procedures, litigation, editorial interpretations, and congressional records to try and decipher the idiocy and figure out what the hell congress meant to say in the first place, which you can be guaranteed will bears no resemblance whatsoever to any common sense or reason.
A "theory" is my best wild-ass guess as to what that "law" means. See above.
An "equation" is Assets = Liabilities + Owners Equity, or Debits = Credits.
And a "Model" is some dumb-ass client who wants to deduct her highlights and mani/pedis as business expense.
Posted by: Maggie May at February 22, 2008 10:00 AMHAHAHAHAHAHAHA!
Posted by: Ken S, Fifth String on the Banjo of Life at February 22, 2008 10:09 AM