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.
An Einstein frame and a String frame are two different ways of describing the same physical phenomena, namely the behavior of gravity. In an Einstein frame, the equations of motion are described using the metric tensor, while in a String frame, they are described using the dilaton field. This results in different mathematical formulations, but both frames are valid and equivalent descriptions of the same physical system.
The two frames, Einstein and String, arise from different theoretical approaches to understanding gravity. The Einstein frame is based on general relativity, while the String frame is based on string theory. Both theories have been successful in explaining different aspects of gravity, and the two frames provide complementary perspectives on the same phenomenon.
The Einstein frame is more commonly used in scientific research, as it is the traditional framework for studying gravity and has been extensively tested and validated through experiments. However, the String frame is gaining more attention in recent years due to its potential for solving some long-standing problems in physics, such as the unification of gravity with other fundamental forces.
No, the two frames give equivalent predictions for physical phenomena. This means that any observable quantity calculated in one frame can be translated into the other frame without changing the final result. However, the two frames may offer different insights and approaches to understanding the same phenomenon.
Yes, researchers can choose which frame to use based on their preferences and the specific problem they are trying to solve. In some cases, one frame may be more convenient or provide a simpler mathematical formulation for a particular problem. However, the final results should be the same regardless of the chosen frame.