Thorium News

NO

Later/never

2040s

2050s

2060s

2070s

The cesium 133 F=3 <-> F=4 hyperfine microwave transition (no change)

Any system based on weighted averages of uncertainty or timekeeping contributions

The strontium 87 1S0 <-> 3P0 optical transition

The ytterbium 171 1S0 <-> 3P0 optical transition

Any other optical transition in ions

Any other optical transition in neutral atoms

Nihonium (Element 113)

Flerovium (Element 114)

Moscovium (Element 115)

Livermorium (Element 116)

Tennessine (Element 117)

Oganesson (Element 118)

Element 119 (Ununennium)

Element 120 (Unbinilium)

Astatine (Element 85)

Francium (Element 87)

Radium (Element 88)

Thorium (Element 90)

Uranium (Element 92)

Plutonium (Element 94)

Curium (Element 96)

Californium (Element 98)

Lawrencium (Element 103)

Actinium (Element 89)

Fermium (Element 100)