The SRians Said: Time is What the Clock Measures

Are they members of the APS ?

http://www.aps.org/resources/

This definition for time implies that a clock second represents the same
"duration" (universal time?) in all frames.

This definition is almost completely useless. And while it may be true, time
is most importantly considered the 4th dimension of Mikowski spacetime.


Question:
Does this mean that a clock second is an interval of universal time?


No. What it means is that time (the dimension), does some really weird and
unexpected things. It's all relative.