Calculadora de Densidad Crítica — Fórmula
## Critical Density of the Universe
The critical density is the dividing line between a universe that expands forever and one that eventually re-collapses.
### Formula
**rho_crit = 3 H0² / (8 pi G)**
- *H0* must be in SI units of 1/s (about 2.27 x 10⁻¹⁸ s⁻¹ for 70 km/s/Mpc)
- *G* = 6.674 x 10⁻¹¹ N m² kg⁻²
The observed value is roughly 9.5 x 10⁻²⁷ kg/m³, equivalent to about 5.7 hydrogen atoms per cubic metre.
The critical density is the dividing line between a universe that expands forever and one that eventually re-collapses.
### Formula
**rho_crit = 3 H0² / (8 pi G)**
- *H0* must be in SI units of 1/s (about 2.27 x 10⁻¹⁸ s⁻¹ for 70 km/s/Mpc)
- *G* = 6.674 x 10⁻¹¹ N m² kg⁻²
The observed value is roughly 9.5 x 10⁻²⁷ kg/m³, equivalent to about 5.7 hydrogen atoms per cubic metre.
Ejemplo Resuelto
Using H0 = 2.27e-18 s⁻¹ (≈ 70 km/s/Mpc).
- rho_crit = 3 H0² / (8 pi G)
- H0² = (2.27e-18)² = 5.153e-36
- 8 pi G = 1.676e-9
- rho_crit = 3 * 5.153e-36 / 1.676e-9
- rho_crit ≈ 9.22e-27 kg/m³