Recent content by haushofer

It's comparable to the time where the geocentric and heliocentric models both successfully explained planetary orbits. It was only in accepting the heliocentric model that modern cosmology could develop. From this modern standpoint the heliocentric model of course is to be preferred. Sometimes...

My advice: don't mention the war or supersymmetry.

Intuitively: if r and v point in the same or opposite direction, L is zero. So only movement in the direction perpendicular to r contributes to L. Those are the angles. By the way, this is also what makes the l=0 states of e.g. hydrogen clasically difficult to understand: it involves movement...

Yes, that's a gread addition. It leaves me with the final question: are all constraints one can impose consistent? And how can we check that? Working everything out for other constraints leaves us in general with second order derivatives and the coefficients themselves, giving the same problem...

Yes, thanks a lot, you're absolutely right. Reading your post I redid the calculation and indeed was missing a factor of p(x) which makes all the difference! I had a strong feeling pW=const. should play a role, but couldn't see it of course. You saved my day! I've seen quite some texts on this...

I found the book: https://people.uncw.edu/hermanr/mat463/ODEBook/Book/ODE2.pdf

Hi folks, I decided to brush up my knowledge of Green's functions and Differential Equations, and came across this chapter, https://people.uncw.edu/hermanr/mat463/odebook/book/greens.pdf of some unknown book (if anybody recognizes it, I'd like to know the title). In 8.3 (page 265) the...

If I understand you correctly: wouldn't that mean that your version of the Kruskal metric still has a coordinate singularity at r=2M? So no, that doesn't seem right.

Ah, the one book, from the one author. My favourite.

Maybe I'm a bit dumb, but you have to be a bit more specific if you want to receive help. Personally I can't make anything out of this. If you want people to help you, put effort in a clear opening post.

Never mind, solved it. This was serious confusion :-p

I guess my confusion is this: why would the hotter sphere cool down a bit by absorbing radiation from the colder sphere?

I think every teacher knows that words are really important in physics. Physics is also about interpretation, or "ontology", or "concepts" as you put it. And that involves wording, which shapes our understanding of everything, including physics. Ultimately, we don't just use math to understand...

My 2 cents: if you're being pushed in your chair because the train accelerates, it's a frame-independent fact that an engine makes the train accelerating. That's why we call this force "real". Your body with inertia just resists this change of speed. In your frame you describe this as a force...

@kuruman I only see now your comment about absorption, emission and minus signs. But isn't the whole point that if (say) sphere 1 absorbs power from sphere 2, eventually this extra energy is reemitted? That's why I choose a plus sign for c.