| Clue | Source | Date |
|---|---|---|
| Part of physics disposed to human query about time | The Times Quick Cryptic | 01 Oct 2025 |
| Brainchild of physicist Max Planck | Eugene Sheffer | 05 Sep 2020 |
| Noted Max Planck contribution to physics | New York Times | 09 Nov 2015 |
| Noted Max Planck contribution to physics | ||
| Planck's Nobel prize-winning formulation | ||
| Planck's brainchild |