Hey everyone, from Srednicki's QFT textbook I've read that there has been work on the following attempt to obtain a relativistic quantum theory: instead of treating space as a label like time, promote time to an operator, such that you get 4-position and -momentum operators. Now I know that there are issues to address, the potential unboundedness of the Hamilton operator and such, but still I would be intrigued to take a look at these attempts. I did a search, but couldn't find anything. So does anybody now of some resources to point me to? If you're interested, said passage can be found on p.10 of Srednicki's book, which can be found via google book search. Looking forward to your responses!