World’s First Nuclear Clock Ticks On, Opening a Window on a Fifth Force

Sources:

• D.C.L. Toscani et al., “A thorium-229 optical nuclear clock with feedback loop,” arXiv:2606.04997 (2026)
• B. Huang et al., “A nuclear clock based on 229-Th,” arXiv:2606.08870 (2026)
• K. Hughes-Castleberry, “The world’s first nuclear clock just ticked on,” Live Science, June 17, 2026