Recent content by KOSS

Yeah, I get that, thanks. I'm still figuring out how to prove these things...

On a bipartite graph a game of cat vs mouse can be played, with say both the cat and mouse starting on a "red" vertex. We colour the vertices so that no two of the same colour are connected by an edge (can always be done with a bipartite graph of course). The game is played by cat and mouse...

Can any math geeks help? Refering to the talk, (Woodin: plenary talk at the 2010 International Congress of Mathematicians) http://bitcast-a.bitgravity.com/highbrow/livearchive40009/26aug-13.45to14.45.flv In Hugh Woodin's 2010 ICM talk on Ultimate L he introduces Godel's constructible...

Thanks again entphy for the clarification. Just so I get it all straight, my interpretation of the mathematics is as follows. The fact that there is an asymmetric field intensity initially does not necessarily imply any force right? There is a force only upon whatever might be a source of...

I just thought of another way to explain this qualitatively to high school students, they just need a smattering of special relativity. (Yeah, I'll get told off for doing this, but what the heck... my students can learn a little more than they are expected to know for exams, it won't kill...

Hi folks, yes I am still following this thread. I thank both Phrak and entphys for their contributions. I'm not so sure there is a deep disagreement. Many physical problems have equally valid, yet seemingly different, explanations. Maybe there is just a language issue in the discussion...

Hey Guillaume, don't give up dude. Part of the fun of forums like this is to engage in debate and test out your ideas. there are loads of physics experts reading the posts who can help you clarify your understanding. Just keep an open mind. there is no guild mentality really, just lots of...

Hey Aravind, see the replies in the thread, https://www.physicsforums.com/showthread.php?t=524617&highlight=discrete+energy" (which should of course read "Why does an atom emit discrete frequencies of light?")

To elaborate on LearningDG's remark, while superpositions are allowed and inevitable, when photon emissions are measured the wavefunction is collapsed according to the Born principle, which picks out a particular discrete pair of energy levels. All the superposition tells you is the...

I have found a few places where the force on the current carrying wire is discussed in terms of "tension" in the B field lines. However, my present understanding is that to make any sense of such language I would still need to talk to my students about the full Faraday tensor. Does anyone...

Here's the textbook page (see attachment):

This question comes under the familiar topic "force on a current carrying wire in a magnetic field". You all know the Lorentz force and F=LI\times B. So I'm teaching a high school class on this and a senior teacher tells me the students will need to explain the force on the wire for their exam...

Whoa! I love some of these olde threads! :-D If anyonez still readin' here's another opinion: Re: ""Einstein's general relativity says no, the fabric of space cannot tear." * You shouldn't read pop sci literature in such a serious way. GR does not say any such thing! GR ASSUMES a...

First, referring to the posts on pages & 2 of this thread - collectively they provide a satisfactory definition of spin. Though some kind PF mentor could probably do us all a favour and summarize. Second. just modify your third grader version: instead of "a consequence of the rotational...

Hmmm,... reading the book draft by Nelson, it seems in IST the notion of a standard natural number is undefined, ---Nelson, page 1 of "Internal Set Theory",http://www.math.princeton.edu/~nelson/books/1.pdf" Oh crap! Just read Hurkyl's reply. Didn't think you'd be reading five years later...