 Let’s try to get a better sense of this. What’s the brute fact required of us? And why should we worry about it? Why should we think that the neo-Lorentzian theory, which is acknowledged to be empirically equivalent to STR (Balashov &amp; Janssen 2003: 23; Callender 2008: 52–53), offers an inferior explanation of both length contraction and time dilation than does STR? Janssen (2002) puts the point as follows: