You all are missing my point.
Let's see, how can I make myself more clear...?
Mass itself cannot be measured directly, it can only be inferred by the
behavior of a mass undergoing acceleration. None of the schemes proposed
here (the balance, the calibrated oscillation -- though that is clever and
would work in zero gravity) measure the mass directly.
The balance compares the weights of two (or more) objects. If they exhibit
the same weight, then they must have the same mass. Still the mass itself
has not been measured, it has only been compared to a standard. (And
whether that standard was water or an alloy is irrelevant to this
discussion.)
The oscillator (essentially a mass on a spring) also does not measure mass
directly. What is measured is the period of the oscillation. Again, this
can be compared to a standard, but the mass is not being measured.
I think it's kind of neat that mass cannot be measured. No one need be
defensive about this!
- John
P.S. I'll have to retract my statement "Show me a device that can measure
mass under zero gravity and I'll admit that mass can be measured.", since
the oscillator works, though still does not measure the mass.
