> Dear Mike, > The conclusions that I drew were based on the reason given by Neville's. > Neville has demonstrated that he is a man of integrity. And since he is a > man of integrity, I accept his reasons for a non-response... (as yet!!). > Perhaps you should re-read his explanation and just be patient! > > Jack Dear Jack, Did you even read the proof? http://www.midclyth.supanet.com/page40.htm You may not understand the maths but surely you understand the statement in the conclusion: "This is a preposterous result, since even the decision to label them this way round in the first instance was totally arbitrary." Of course, the word "even" suggests that there is another reason for this result being preposterous but no reason is given other than the fact that the labelling was arbitrary so we can only assume that what is meant is that whichever particle is labelled 1 will have a total before and after velocity greater than the other (which would be preposterous). You may not be able to see how each line in the maths is derived from the previous ones but surely you are able to do what I did and substitute some numbers in for u1..v2, and work out the resulting numerical equation for each line of the proof. If the numbers are chosen so that equations (1) and (2) give true numerical statements, then the conclusion (which is derived solely from these equations) should also give a true numerical statement or *the maths in the proof* is wrong. I urge you to try this out, and then swap u1 for u2 and v1 for v2. Regards, Mike.