For Good Measure

"A decision, made at the 26th meeting of the General Conference
on Weights and Measures (CGPM), means that from 20 May 2019 
all SI units are defined in terms of constants that describe the natural world.
This will assure the future stability of the SI and open the opportunity
for the use of new technologies, including quantum technologies, 
to implement the definitions."

On the trail of accurate absolutes

Complete precision must agree

No time left to second guess

The measured metre perfectly

No cagey sham a perfect kilogram

The A for amperes proper charge

Thermodynamically for kelvin’s T

Amounts of substance moles at large

Resplendent bright intensity

Outside or inside in the cellar 

To measure best you’ll need cd

The light of which we call candela

Therefore second, metre, kilogram

Ampere, kelvin, mole

No matter where you need to see

The candela lights the whole