I did say "questions", not logical arguments. smile

I'd appreciate some maths help here, please.

A particle travelling at 0.9c from emitter to detector is timed by observer 1, who is stationary relative to both emitter and detector, as taking 1 sec to cover that distance.

Observer 2 is travelling (in the direction from detector to emitter) at 0.8c.

What time does observer 2 record for the particle?
What equation is used to determine this?

Of course you can see where this is going, but that's OK, its not a "try to catch Orac" exercise. smile

There never was nothing.