Related Clues:
- 1950s filmstrip, "Our Friend, the ___"
- Fermi's tidbit
- Fermi's particle
- Very little bit
- Tiny source of energy
- It gets smashed
- Subject for Bohr
- Lepton site
- It's smaller than a molecule
- Bit of matter
- With 41-Down, nuclear device
- Bit to be split
- Democritus' indivisible unit
- Nuclear fission target
- Very small matter