The square root of a quantity denoted by this letter approximates the linear structure growth rate f and is strongly correlated with sigma-8. Jim Peebles defines the dimensionless parameter E as the harmonic mean of several quantities denoted by this letter, weighted by powers of a. The cube root of a ratio of two quantities denoted by this letter determines when the matter-dominated era ended. A dimensionless value approximately equal to 0.7 is denoted “[this letter]-sub-lambda,” while similar values are about 0.05 for baryons and 0.3 for matter. Another value denoted by this letter was measured to be approximately one by the Planck collaboration, implying that the universe has almost zero curvature. For 10 points, name this Greek letter that represents the ratio between energy density and the critical density, the density parameter. ■END■
| 2025 ACF Nationals | 04/19/2025 | Y | 24 | 29% | 0% | 38% | 94.43 |
| Player | Team | Opponent | Buzz Position | Value |
|---|---|---|---|---|
| Rasheeq Azad | North Carolina A | Indiana | 64 | -5 |
| Russell Nip | British Columbia | Ottawa | 64 | 10 |
| Athena Shadden | Texas | Iowa State | 67 | -5 |
| Jeremy Cummings | WUSTL A | UC Berkeley A | 71 | 10 |
| Geoffrey Wu | Columbia A | Waterloo A | 73 | 10 |
| Shardul Rao | Minnesota | Virginia Tech | 75 | -5 |
| William Groger | Columbia B | Cornell B | 93 | 10 |
| Yashwanth Bajji | Michigan | UCF | 103 | -5 |
| June Yin | WUSTL B | Georgia State | 104 | -5 |
| Tim Morrison | Stanford | Illinois A | 107 | -5 |
| Matt Schiavone | Northwestern | Chicago A | 109 | -5 |
| Teigue Kelly | Penn State | Arizona State | 110 | -5 |
| Liam Starnes | Chicago B | Georgia Tech | 112 | -5 |
| Gavin Markoff | Vanderbilt | Illinois B | 113 | 10 |
| Anuttam Ramji | UC Berkeley B | NYU | 114 | 10 |
| Amogh Kulkarni | Georgia State | WUSTL B | 133 | 0 |
| Rohan Dalal | Georgia Tech | Chicago B | 133 | 0 |
| Jonathan Huang | MIT | Harvard | 133 | 10 |
| Joseph Chambers | Virginia | North Carolina B | 133 | 0 |
| Soren Heydari | North Carolina B | Virginia | 133 | 0 |
| Cade Reinberger | RIT | Ohio State | 133 | 0 |
| Calvin Bostleman | Ohio State | RIT | 133 | 0 |
| Benjamin Chapman | Toronto A | Rutgers | 133 | 0 |
| Aum Mundhe | Rutgers | Toronto A | 133 | 0 |
| Alex Akridge | Indiana | North Carolina A | 133 | 0 |
| David Bass | Johns Hopkins | Toronto C | 133 | 0 |
| Jason Zhang | Toronto C | Johns Hopkins | 133 | 0 |
| Andy Huff | LSE | Florida | 133 | 0 |
| Leo Law | Florida | LSE | 133 | 0 |
| Noah Chin | Virginia Tech | Minnesota | 133 | 0 |
| Andrew Wang | Illinois A | Stanford | 133 | 0 |
| Conor Thompson | Iowa State | Texas | 133 | 0 |
| Richard Niu | Cornell A | Toronto B | 133 | 0 |
| Kunaal Chandrashekar | Toronto B | Cornell A | 133 | 0 |
| Shiva Tegulla | UCF | Michigan | 133 | 0 |
| Bryan Ugaz | Arizona State | Penn State | 133 | 0 |
| Adam Fine | Chicago A | Northwestern | 133 | 0 |
| James Ah Yong | Waterloo B | Yale | 133 | 0 |
| Andy Yu | Maryland | Winona State | 133 | 0 |
| Henry Bon | Winona State | Maryland | 133 | 0 |