Individually, I know all of these words…
Local Lorentz covariance is satisfied, which is all that is usually meant when discussing the validity of Special Relativity. In other words, we wouldn’t throw away Special Relativity if we found ourselves in such a space-time topology. General relativity and local Lorentz Covariance are still perfectly good. See here to be reminded about ‘local’ vs ‘global’ in relativity. In this case, the fact that relativity is satisfied locally but not globally is experimentally expressed by the fact that frame-dependent effects can only be measured by literally traversing an entire loop around the universe. And of course the entire point of the article I cited was to discuss the interesting consequences of a space-time that satisfies local but not global Lorentz covariance. Indeed globally there is a preferred frame, and it is quite intriguing how that preference is manifested, and how the paradox is resolved.
This thread has taken a very interesting (and conceptually difficult) turn. Thanks guys and gals. Stimulating as always.
Indeed, and I’m going to have to think about this one some more.
He was referencing this:
Colonel Sandurz: You’re looking at now, sir. Everything that happens now is happening now.
Dark Helmet: What happened to then?
Colonel Sandurz: We passed then.
Dark Helmet: When?
Colonel Sandurz: Just now. We’re at now now.
Dark Helmet: Go back to then.
Colonel Sandurz: When?
Dark Helmet: Now!
Colonel Sandurz: Now?
Dark Helmet: Now!
Colonel Sandurz: I can’t.
Dark Helmet: Why?
Colonel Sandurz: We missed it.
Dark Helmet: When?
Colonel Sandurz: Just now.
Dark Helmet: When will then be now?
Colonel Sandurz: Soon.
Erm… yeah I know. Thanks though!
Just found another mystery - the dynamo effect: how does the Earth’s core create its magnetic field? We know there’s a relationship between electricity & magnetism (u can create a magnet with electricity & coils, and spinning magnets like in a turbine can create electricity), but geologists still can’t explain why molten iron in Earth’s core generates the magnetic field as big as it does, and in its configuration.
That’s pretty misleading. See the wikipedia page, for example. We understand pretty well how the Earth’s magnetic field may (and probably is) generated, but, as wikipedia states: “The equations for the geodynamo are enormously difficult to solve, and the realism of the solutions is limited mainly by computer power.”
Ok, so we know that it worx, but not why. The conditions at the core are so extreme, there’s not (yet) a way to probe. There is an experiment on going, but as it stands, we don’t know for sure - there may turn out to be a previously unknown factor.
We know the “why” as well as we know any “why” in science.
I can’t believe everyone missed this one…
Someone on the first few pages brought up tides as an unexplained phenomena. However, in my 8th grade science class (which, for you haters out there, I know is not very advanced and can turn out to have some false answers) we learned that the separate pulls of the sun and moon on the oceans create tides. There are whole, mass-produced calendars with tides and moon phases printed on them, I’m pretty sure.
And let me just say for the record that I did absolutely no research on anything in my post while I was writing it. However, we spent a whole month on moon/sun/earth/ocean relationships only 2 years ago, so I’m fairly certain I’m remembering accurately. Deal with it.
The tides thing was a joke.
I knew that! :smack:
There are lots of “miscellaneous” phenomena that are quite wide open in terms of explanations. Of course, most are mentioned in wikipedia’s list of unsolved problems in science (which someone posted about 3 replies into this thread), but just to specify one in particular I came across recently and found interesting: sonoluminescence
Sorry to hear that. I had my GB out 21 years ago this month, and never experienced a day’s difficulty from the absence of it. I had hepatitis C (I don’t any more, yay), and my liver took quite a beating over the years, so if any liver were to be overwhelmed, you’d think it would have been mine. Can science explain why some people have problems post-cholecystectomy and others don’t?
In more detail, it was a Bill O’Reilly quote in reference to the whole creationism-in-school thing. He’s apparently in favor of it because science can’t explain a lot of things, like tides. :smack:
The scary thing is, he didn’t mean it as a joke.
That’s OK. Science can’t explain Bill O’Reilly, either.
The thing is, ICP gets a lot of stick for that, and I’m not saying they’re geniuses with an actual point in their ugly painted heads, but it’s actually a good question that I asked on this board recently: what is an electric field made of? - Factual Questions - Straight Dope Message Board
The answer is that we don’t actually know how magnets work. From what I gathered, there is something in the nature of the universe that creates a potential field between charged particles so that they naturally move toward each other and release energy as they do it.
Nobody claims to actually describe it well, only to predict its actions.
We literally understand electromagnetism better than we understand anything else in the Universe. To say that we don’t really understand magnetism is just to say that we don’t actually understand anything. It’s like the typical conversation with a three-year-old, who asks “Why?” to everything you say. Eventually, you just have to give up, no matter what the topic is.