 Do you see the  difference between:   2* (80,0,0,16) = (60,0,0,20)   and:   2 * tau(80,0,0,16) = tau(0,0,0,0) + tau(60,0,0,20)   (Hint: the difference is huge, like night and day.) Hmm.... let's see if I can work it out myself... don't tell me, ok? 2*(80,0,0,16) = (160,0,0,32) which is not equal to (60,0,0,2) so that is FALSE. tau(60,0,0,20) is... err... according to the wacky transforms ... tau(x,0,0,t) = (t  vx/c^2) /sqrt(1  v^2/c^2) = (20  3*60/25)/sqrt(1 9/25) = (20180/25)/sqrt(16/25) = 12.8/0.8 = 16. tau(0,0,0,0) = (0  3*0/25)/0.8 = 0 So tau(0,0,0,0)+tau(60,0,0,20) = 16. 2* tau(80,0,0,16) = 2* (16  3*80/25)/ 0.8 = 2* (16  9.6)/0.8 = 32 32 = 16. So that is FALSE. I see no difference between FALSE and FALSE. Please tell me what the huge difference like night and day is. 

Fumble Index  Original post & context: nm81f.70848$iW5.9345@fe3.news.blueyonder.co.uk 