Recent content by ibc

(not assuming any kind of continuum hypothesis of course) does every cardinal have a following one, i.e a minimal cardinal that is strictly larger?edit: ops, the title should be "following cardinal"

It's probably very university dependent, however, where I study there are people going from minor math undergraduate degree to pure math graduate, but they surely do more than those analysis and linear algebra courses you mentioned (at least a few of {topology, complex analysis, logic, set...

[take under consideration that courses vary between universities, not to mention between countries...] So to clarify, the CalcIII I did was mostly about multidimensional functions and multidimensional integrals, which is very useful to physics courses in general and to physics II in particular...

A force that is always perpendicular to the direction of motion does not change the magnitude of the velocity. One way of seeing it is considering the energy a force insert to the system (or the energy per unit time): P=\vec{f}*\vec{}v = 0 Another way is simply taking the derivative of...

Thanks for the information. So by what you say, most master's degree students are not doing it with a scholarship, in the UK? (I'm only referring to master's degree in exact science, of course when it comes to law school, medicine and such, most people need the degree to get a job elsewhere...

Hello I'm soon starting my third (and last) year to my bachelor's degree in math (primary, and a bit physics too) in a non-English-speaking country, and I'm thinking of doing a master's degree abroad (by abroad I mean USA, UK, or anyplace where they speak English) So I've been wondering how...

I don't understand. Take N= natural numbers N\subset \cup N_n where N_n is all the natural numbers up to n. it is a chain, and obviously N is not contained in any finite union. (and obviously there are similar less "dramatic" examples (where the subset is not all the union)) yes...

Hello I'm reading Y. Manin's http://books.google.co.il/books?id=8NTWRFD5lZ8C&printsec=frontcover&dq=yuri+manin+introduction+to+mathematical+logic&hl=en&ei=cfp_TJ2vJ8KSjAeB-6xl&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCkQ6AEwAA#v=onepage&q&f=false" and I've been having some difficulties. So...

I was wondering if the author would appreciate being nagged by such things, or stuff like that are better being referred to the publisher? (or it isn't the publisher's job to take care of such things?) In any case your site seems cool, I'll make sure to send my list there too. By the way...

Hello Say I'm reading a (scientific) book, and find all these small errors in it (typos and stuff, nothing serious). Is there anyone to send a list of all these errors, for the benefit of future printings? (does anyone care?) Thanks

Hello I've been told that a (real) Lipschitz function (|f(x)-f(y)|<M|x-y|, for all x and y) must be differentiable almost everywhere. but I don't see how I can prove it. anyone has an idea? Thanks

The main reason for which we eventually get our results, in this derivation, is the standing waves, which is a direct result of the geometry of the problem. I wouldn't expect any standing waves if I had a body radiating outwards into space. Also, what does it mean that the radiation is...

Perhaps I'll try to rephrase it compactly: 1) Why is the problem of a radiating black body equivalent to that of an inwards radiating cavity? 2) How is the energy density inside this cavity proportional to the radiation intensity (units of energy density / time)? Thanks again ibc

Hey In several books, the derivation of black body radiation is done by considering the energy density inside a cavity surrounded by walls in a certain temperature. The derivation is described as one of the first steps in quantum mechanics, where all considerations are purely classical but...

I really have no idea what you're talking about (nor what it has to do with anybody's native tongue). The Huygens-Fresnel principle is not just an expression to the diffraction of light, it's a way to characterize the wave in many circumstances. What I'm looking for is the derivation for the...