减速参数计算器 — 公式

The Deceleration Parameter

The deceleration parameter q₀ tells us whether cosmic expansion is speeding up or slowing down.

Formula (matter + Lambda)

q0 = Omega_m / 2 - Omega_Lambda

  • Positive q0 means deceleration (gravity wins)
  • Negative q0 means acceleration (dark energy wins)

    • Current values give q0 ≈ -0.535, confirming accelerating expansion.

    计算示例

    Standard cosmology: Omega_m = 0.31, Omega_Lambda = 0.69.

    1. q0 = Omega_m / 2 - Omega_Lambda
    2. q0 = 0.31 / 2 - 0.69
    3. q0 = 0.155 - 0.69
    4. q0 = -0.535