Question
This limit is surpassed by rare “extreme-energy” particles. For 10 points each:
[10h] Identify this upper energy limit approximately equal to 5×10 19 electron volts. Particles above this limit lose energy via the production of pions formed by the decay of a delta resonance.
ANSWER: GZK limit [accept GZK cutoff; accept Greisen-Zatsepin-Kuzmin limit or cutoff]
[10m] One notable particle with energy above the GZK limit was this cosmic ray detected in 1991. With an energy of 51 Joules, roughly the same as a 60 mph baseball, it is currently the highest energy cosmic-ray ever recorded.
ANSWER: Oh-My-God particle
[10e] The GZK limit is derived by assuming cosmic rays lose energy through scattering interactions with photons from this body. This largest blackbody in the universe has a temperature around 2.7 Kelvin.
ANSWER: CMBR [accept cosmic microwave background radiation]
<Science - Physics>
Summary
| 2024 ARGOS @ Brandeis | 03/22/2025 | Y | 3 | 6.67 | 33% | 33% | 0% |
| 2024 ARGOS Online | 03/22/2025 | Y | 3 | 23.33 | 100% | 100% | 33% |
Data
| CLEVELAND, THIS IS FOR YOU! | Aw we're so sorry to hear that maman died today, she gets five big booms | 10 | 10 | 10 | 30 |
| Thompson et al. | I wish it were possible to freeze time so I would never have to watch you retire | 0 | 10 | 10 | 20 |
| throw away your cards, rally in the streets | UBC | 0 | 10 | 10 | 20 |