The discussion revolves around the concepts of "Einstein frame" and "String frame" within the context of cosmology, particularly in relation to string theory. Participants seek to clarify these terms and their implications in theoretical frameworks.
Participants do not reach a consensus on the meanings of the terms, and the discussion reflects varying levels of understanding and familiarity with string theory concepts.
Some assumptions about the familiarity with string theory and cosmological models may limit the clarity of the discussion. The dependence on specific definitions and the implications of the dilaton field are also noted but remain unresolved.
windy miller said:I have listening to talks come across the terms"Einstein frame" and "String frame"
sure for example herePeterDonis said:Can you give any specific references?
windy miller said:sure for example here
https://arxiv.org/pdf/hep-th/0608200.pdf
thanksPeterDonis said:From equations (2) and (3) in that paper, it looks like the "Einstein frame" is the usual FRW coordinates used in standard cosmology, and the "string frame" is a conformal transformation of those coordinates that rescales time and distance in a way that varies with the value of the dilaton field ##\phi## (and also depends on the number of dimensions ##N## in the underlying string theory, but that will be constant for a given model). Since the dilation field ##\phi## presumably varies with time, the conformal factor will also vary with time. Presumably this conformal transformation is convenient for string theory, but I am not familiar enough with string theory to know why.