Schreiber message to the h-bar

The following is a message in reply to some discussion in some forum called “h-bar”. That forum only admits a handful of symbols to be posted at a time, so I have to relay the following reply from here. If you come here from elsewhere than the h-bar, then you are out of context and should leave.

Maybe the following information helps:

Part of the motivation behind the nLab site (see the Wikipedia entry about the nLab) is that there are many important developments in mathematical physics these days which are rooted in recent progress in homotopy theory but for which practicing physicists will have a hard time tracking down the relevant entry points, or of which practicing physicist will have a hard time even becoming aware of (as maybe this dicussion here shows).

A pivotal point of this development is probably Lurie‘s proof of the cobordism hypothesis (which makes him rank position 3 among Fields medal candidates this year see and work by Daniel Freed et al. on developing the connection of this to fundamental physics.

We have published a collection with the American Mathematical Society which reviews these and other developments, see

The reason why I am linking a lot to the nLab is because I think in present times theoretical physics suffers from a lack of understanding of fundamental terms that are thrown around in discussion, and that I think a good answer should provide references for each technical term that it uses. The nLab pages are meant to provide this. Mostly they give commented discussion of established literature, Wikipedia links and everything, but also some pointers to more modern developments in homotopy theory, which mostly cannot be found via other links. If anyone spots an actual mistake or misstatement on the nLab, point it out and we’ll fix it (turn to the “nForum” for that).

Notice that the nLab is widely cited on MathOverflow (this ís the research-level mathematics SE discussion group which, if I may say this, has a good bit higher average quality than the current Physics.SE site, notably Mathoverflow has lots of active bigshot mathematicians participating); it is referred to as a standard cite to turn to before asking questions (see here:

Since string theory was mentioned, let me say that I understand that some string theoretic considerations can get on people’s nerve’s from time to time (even though I think it shouldn’t) but in the case at hand where the discussion is about basic concepts of 20th centure physics – the role of fiber bundles in physics, to wit, which was born together with differential geometry as the language for gravity and gauge field theory at the beginning of the last century – I think every physicist with some basic education should have an easy time confirming that my message reviewed the broadly accepted state of the art, pointers to modern reviews including.

In fact the content of my message was to a large extent duplicated in a second reply by another contributor that appeared later in its thread. Now, that my message had links to more information for each technical keyword appeared, while the other message did not, is hardly to be used against the original message, is it? I think the whole Physics.SE site would benefit from people providing more details on the actual definition and usage of technical terms.

There is so much confusion in physics with people handling terms, specifically in field theory, which they only associate a vague understanding with. We can all improve on that, if only we show a minimum tolerance for mathematical language. Because, like it or not, that is the language is which physics is formulated.

Created on September 16, 2013 at 17:08:55. See the history of this page for a list of all contributions to it.