SI redefinition
The main challenges facing the modern world today are measurable. We measure the world in seconds, meters, kilograms or amps. In the overwhelming majority of countries we use the International System of Units of Measure (SI), which integrates almost the whole world into a coherent metrological whole.
Consistent, uniform metrology takes care of our health, environment, trade, science, technology and safety. However, modern metrology faces a new challenge: the redefinition of SI, which will make metrology ready to meet the demands of modernity in the 21st century.
Basic constants
|
∆νCs |
9 192 631 770 s-1 |
|---|---|
|
c |
299 792 458 m s-1 |
|
h |
6,626 070 15×10-34 J s (J s = kg m2 s-1) |
|
e |
1,602 176 634×10-19 C (C = A s) |
|
k |
1,380 649×10-23J K-1 (J K-1 = kg m2 s-2 K-1) |
|
NA |
6,022 140 76×1023 mol-1 |
|
Kcd |
683 lm W-1 (dla monochromatycznego promieniowania o częstotliwości 540×1012 Hz) |
SI Units
|
1 s |
9 192 631 770/∆νCs |
|---|---|
|
1 m |
(c/299 792 458) s ≈ 30,663 319 c/∆νCs |
|
1 kg |
(h/6,626 070 15×10-34) s m-2 ≈ 1,475 521… ×1040 h ∆νCs c-2 |
|
1 A |
(e/1,602 176 634×10-19) s-1 ≈ 6,789 687×108 ∆νCs e |
|
1 K |
(1,380 649×10-23/k) kg m2 s-2 ≈ 2,226 6653 ∆νCs h k-1 |
|
1 mol |
6,022 140 76×1023 NA-1 |
|
1 cd |
(Kcd/683) kg m2 s-3 sr-1 ≈2,614 830×1010 (∆νCs)2 h Kcd |
Information on the SI redefinition is also available on the BIPM website.