What is time?Afirst,intuitiveanswer maybethat time isadimension of thephysical universe. As such, it existsand has always existed independentlyofhuman experience.Wethus find it natural to assigntemporal identitiestoeventsthat took place millions ofyearsbefore humanity even came into being,inpar-ticular in areas such as astrophysics,geology, and palaeontology. Weknow,orwe think we know,that the …