KeeTov & ExtrVet> "...can't stand the symmetry of 999..."
Nah, I was just worried that someone would turn it upside down and accuse me of having occult interests. [img]smile.gif[/img]
BobB & others - Thanks for your kind words.
Rusty and Bonni - Don't worry about getting the lead out... When I woke up this morning, I didn't feel any different now that I'm on this side of the 1000 mark. [img]smile.gif[/img]
Fox - You always ask "real good ones", don't ya. For the full story, put Feynman, Lectures in Physics v. II on your bedside table for a month or two and browse through it a few pages at a time when the spirit moves you. If you have never looked through this book, its a great read. Altho its supposed to be pitched at 2nd term Physics majors, anyone from a seriously interested layman all the way up to grad students in Physics can read, enjoy, and profit from it.
If you don't want to take this route, try this explanation for size. Imagine a strange country, Foamland, in which every object is surrounded by a sphere of completely transparent foam rubber. Nobody knows why this is so, or who put these spheres in place, but this is just the way it happens to be in these parts.
In Foamland, when one object starts getting close to another they start pushing each other apart - gradually at first, and more forcefully as they get closer together. The best scientists and philosophers in Foamland got together to try to "understand" this. They formulated lots of detailed mathematical rules about how objects in Foamland interact, and can make wonderful predictions about the behavior of objects in Foamland, but they can never answer the question, "why does it *really* work this way".
To a large extent, this is what we are fundamentally faced with in trying to achieve a deep understanding of electromagnitism. You asked, "...where does the energy come from to move the object towards the magnet...". In the mythical country of Foamland, the corresponding question would be, "Where does the energy come from that pushes other objects away?" You know perfectly well that the foam is simply acting like a spring, and if you force one object closer to another you store energy in this spring, but YOU were the one putting the energy into the spring. The spring is just sitting there and can store the energy you are putting in. It doesn't need to have "latent energy" at the start to make it work.
It's pretty much the same thing with E/M. Charged or magnetized objects interact with each other (even in a vacuum) according to well known rules, and if you push one positively charged object towards another positively charged object, they will act much like the objects in Foamland where the foam is completely invisible to the inhabitants, and can only be sensed by its effects on how objects interact. Magnetized objects follow a slightly different set of rules, but the underlying story is still the same: "This is the way it is!".
Around the late 1800's scientists in Foamland started hypothesizing the existence of "foam", an invisible field surrounding all objects. Around the same time, in our universe, scientists started to generate mechanistic concepts like fields, field lines, exchange of virtual particles, etc. to explain the behavior of objects in our universe, but these aren't "reality", anymore than invisible foam is. They are just ways that help us get our heads around such oddball fundamental behavior of objects.
Anyway, to answer your specific questions, Fox:
1) "Where does the energy come from to move the object towards the magnet?" - Ans: From whatever is moving the magnet around. Think of it as a stretched spring that unlike normal springs, gets stronger the closer the objects are to each other.
2) "Does the magnet 'transmit' energy to the object, thus enabling it to move?" - Ans: The magnet transmits a force to the object, almost exactly like a spring would. Does a spring 'transmit' energy? No, it stores and releases energy, and transmits forces.
3) "Does the earth suck?" - Ans: It depends on my mood.
HTH. The world is quite something when you examine it in detail, isn't it?
Tom / PM[ April 16, 2003, 05:53 PM: Message edited by: PhysicsMan ]