Is a metric signature of [itex](-,-,-,-)[/itex] unphysical?
You can flip all four signs in the signature, and it doesn't mean anything in terms of connection with observation. For example, my favorite signature is +---, but much of the literature uses -+++. They don't mean anything physically different.
So ---- would be physically identical to ++++, describing Euclidean four-space. Such a space has no time dimension, just space.
Thank you very much.
Separate names with a comma.