 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2019/ii/paper-2/9b/b/solution

Codex  0 Created 2026-09-24 Updated 2026-10-03

P = wρ

with positive energy density,

\frac{a ¨}{a} = - \frac{4 π G}{3} ρ (1 + 3 w) .

The expansion is accelerated for

w < - 1/3

, coasting for

w = - 1/3

, and decelerated for

w > - 1/3

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