The units of time(both absolute time and duration)most practical to use when dealing with very long times,e.g.in Nuclear Chemistry and Earth and Planetary Sciences,are multiples of the year,or annus(a).Its proposed de...The units of time(both absolute time and duration)most practical to use when dealing with very long times,e.g.in Nuclear Chemistry and Earth and Planetary Sciences,are multiples of the year,or annus(a).Its proposed definition in terms of the SI base unit for time,the second(s),for the epoch 2000.0 is 1 a=3.1556925445 x 10^(7)s.Adoption of this definition,and abandonment of the use of distinct units for time differences,will bring the Earth and Planetary Sciences into compliance with quantity calculus for SI and non-SI units of time.展开更多
文摘The units of time(both absolute time and duration)most practical to use when dealing with very long times,e.g.in Nuclear Chemistry and Earth and Planetary Sciences,are multiples of the year,or annus(a).Its proposed definition in terms of the SI base unit for time,the second(s),for the epoch 2000.0 is 1 a=3.1556925445 x 10^(7)s.Adoption of this definition,and abandonment of the use of distinct units for time differences,will bring the Earth and Planetary Sciences into compliance with quantity calculus for SI and non-SI units of time.
