In the muons experiment the flow is measured at top of a mountain and at the base of the mountain. The velocity of the muons was calculated http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/muonex.html The velocity is 5 times the speed of light, which is of course against the relativity theory. The scientists downgraded the velocity to make it compliant with the relativity theory. Now with the "new" velocity" the flow measurement is not consistent with the calculation any more, as one would expect . So time dilatation and length contracton has been assumed to make it consistent once again http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/muon.html#c1. And I am confused . Which was first? The chicken or the egg?