Nor does 20th (21st) -century physics countenance the idea that there is anything ontologically special about the past, as opposed to the present and the future. In fact, it fails to use these categories in any respect, and teaches that in some senses they are probably illusory. So there is no support in physics for the idea that the past is “fixed” in some way that the present and future are not, or that it has some ontological power to constrain our actions that the present and future do not have. It is not hard to uncover the reasons why we naturally do tend to think of the past as special, and assume that both physical causation and physical explanation work only in the past present/future direction (see the entry on thermodynamic asymmetry in time)... I am not referring to the time directions (toward-the-past, toward-the-future), which are certainly legitimate enough in physics and do sometimes play important roles. Rather, I am referring to our intuitive ontological division of history into the past, the present, and the future. “The present” in particular is not to be found in any physical theory's description of the world. And special relativity theory undermines the traditional conception of a non-observer-relative present
I read something in the SEP that suggests that, if you take physics seriously, then time can have a direction, but there is no present and so strictly speaking no future that hasn't happened yet or fixed past. Then A times are nothing in addition to B times: the A series is an illusion.
That could be existentially untenable, much more so than moral anti-realism or even solipsism. Is Bertrand Russell dead, or is he alive until he's 97? How old is Noam Chomsky? What's going on? Are these philosophers just talking the talk? Or is there a present nonetheless, with true utterances about A times, even-though A times are not objective?
In any discussion about whether the now is objective, we need to remember that the term "objective" has different senses. There is objective in the sense of not being relative to the reference frame, and there is objective in the sense of not being mind-dependent or anthropocentric. Proponents of the B-theory say the now is not objective in either sense.
I think part of the problem is that I don't know what "relative to the reference frame" means: whether a time that isn't can still meaningfully exist, and if so what metaphysical commitments we have to make.