T
Tomdstone
Guest
Answers:Tom
A couple of questions:
Yppop
- If Maldacena duality provides a non-perturbative formulation of string theory with certain boundary conditions; just what are those boundary conditions?
- Since anti-deSitter space has a negative (attractive) cosmological constant, isn’t that in conflict with a current observation of a positive cosmological constant and an accelerated expansion of the universe?
- Are you a physicist? BS, MS, PhD?
- I believe that they are Dirichlet BC. How much detail do you want?
- It is possible that back reaction effects may lift the universe from an AdS phase to an inflating universe and I suppose that you may wick rotate from dS to Ads. However, I thought that WMAP results have shown that our universe has a positive cosmological constant, so I don’t think that the universe we live in today is an AdS space with negative cosmological constant. The AdS/CFT correspondence is useful not because the universe is an AdS space, but because it is helpful mathematically in solving certain problems. There is a paper by James B. Hartle, S. W. Hawking, Thomas Hertog which claims that “a wave function in a gravitational theory with a negative cosmological constant can predict an ensemble of asymptotically classical histories which expand with a positive effective cosmological constant. This raises the possibility that even fundamental theories with a negative cosmological constant can be consistent with our low-energy observations of a classical, accelerating universe.” But I suspect that there might be an error in that paper.
arxiv.org/pdf/1205.3807v3.pdf - I have a general interest in varying topics. I am working part time with a janitorial cleanup job, cleaning toilets, washing floors, sweeping up, etc., which is not too bad, except that my boss is a tyrant. I got a cup of coffee at break time, and sat down to take a sip when all of a sudden he comes storming in, screaming and yelling that I was spending too much time for the break.