[net.physics] arbitrariness

bte (08/10/82)

 In response to Doug's question about units:
As far as I can tell, a scientific measuring system can be set up
with any forms of units *undefined*, so long as they are not intercon-
nected. For example, the system we use now has as its basis of
measurement space, time, and mass. (There are those who say that
charge is undefined, but it can be defined by the definition of
an Ampere.) However, an equally valid sysytem could be set up
using action, speed, and momentum. (For those of us who haven't
had physics in quite some time:
	  action = energy*time (joules times seconds, or kilograms
	     times {meters squared} over seconds), the units
	     of Plank's Constant
	  momentum = mass*velocity (kilograms times meters/second,
	     a strange something which is conserved)
	  speed = distance/time (meters per second, the units of
	     lightspeed)
Since two of these units have fundamental constants associated with them,
and the third is (for some reason) important, the action-speed-momentum
system is seen as a good replacement for space-time-mass units systems.
 Then, of course, the question "What is time?" is answered, "Action
divided by (speed times momentum), of course!"
    Something to think about, at least.
				Blackhand the Evil
				unc!bte