Recent content by eforgy

This is a neat trick and Urs used something like this to define a metric in our paper (something I had failed to do on my own for 6 years!). I think I'll point out a few things though. First, if you have another map T:\mathcal{H}\to\mathcal{H}, then T T_\phi = T_{T\phi}. From this it...

Piecewise Smooth Manifolds and Diffeomorphisms Hello, There is an entire field of mathematics studying "piecewise smooth manifolds" and their respective diffeomorphisms, which are precisely homeomorphisms that are smooth except on a set of a measure zero. As has been pointed out (and is...

I agree 100% and I think from what I've read that Peter would agree too. The point is, as Peter more eloquently stated, that things seem to have gotten to the point where research in nonstringy ideas is discouraged (at least indirectly by lack of funding opportunities). That is sad. I'm...

Oops! Oh well. That is less fun then :) I read the first post by selfAdjoint (without noting the earlier March date) pointing to the weblog, but I did so just yesterday so the first entry I saw there was his April 1 entry. I assumed this whole thread represented a duping by him on us all :)...

April Fools! Peter must be getting a good chuckle out of this thread (if he's aware of its existence) :)

Greetings from California Hello! Man, I almost forgot how nice the weather is here in California. I am really dreading the trip back to Boston! :) I can't agree more about the 'growl growl' nonsense. With things like that the chance of having a serious discussion here is basically nil...

Nice! :) I just read this and highly recommend it. Eric PS: Urs, this constraint business is something I haven't thought much about. It gives me a new interpretation of the subspace of paths for which \partial^2 = 0 . This is like the "physical" space.

Give him a break Hi Marcus, In Urs' defense, I happen to know that he will be away for the next three days enjoying a nice internet-free vacation on the beach. I think that instead of insinuating that Urs is being somehow academically underhanded by not provided you the references AGAIN...

Hi Marcus, I'm no expert either, but I can tell you what I understand of Urs' stance on this issue. He can elaborate more if I miss the point. I don't think anyone thinks Rovelli's (or Thiemann's) stuff is mathematically faulty. The only thing Urs is claiming is that LQG represents a...

Moderators I still can't seem to bring myself to support this group with Lubos listed as a moderator. His insulting behaviour is intolerable and this would just give him free reign to blast people with impunity. I need to decide if I will simply not vote or give a NO vote. Eric PS: I...

Hi Urs, Let me state in my words how I am beginning to understand this. I am sure I am just repeating what you've been saying all along (assuming what I say is correct that is). In the "usual" approach, you take your constraints and "quantize" them directly as operators on some hilbert...

I can do a little better than this. Looking back at the earlier posts here, I'd write down e^{p^2-m^2}|\psi\rangle = |\psi\rangle. Since p^2 commutes with m^2, I guess we could write this as e^{p^2} |\psi\rangle = e^{m^2} |\psi\rangle, but I don't know if this buys us...

Thanks lethe for starting to solve this exercise. It's been so long since I've looked at QM that I wouldn't have had a chance to get as far as you did. But picking up where you left off, I think Urs simply wants you to look at the equation p^2|\psi\rangle = m^2|\psi\rangle and note...

Hi selfAdjoint, The problem is not with the locality of my version. I assure you that generalized Stokes theorem is not a local theorem. It is defined globally. I still didn't put my finger on exactly what the issue is, but based on Jeff's comment, I am thinking that it might be related to...

Hi Jeff, Thanks. I tried to read through the paper. I can't say that I understand it (yet), but I do see that what he means by Gauss' law is not the same as what I mean by Gauss' law. To me (and most geometers I would think), Gauss' law is just an incarnation of the generalized Stokes...