Dark energy and accelerated expansion

Equipment

• Schematic expansion-history graph $a(t)$
• Slider “Tỉ phần vật chất Ωₘ” (matter fraction)
• “Góc nhìn” (view angle) control and draggable canvas
• “Tạm dừng” (pause) button

Procedure

1. Read the expansion curve

   Start with the default $\Omega_m$ and follow the curve $a(t)$ from the past to today. The slope of $a$ is the expansion rate; in a matter-dominated era $a\propto t^{2/3}$, while dark energy drives faster, roughly exponential growth at late times.

2. Sweep the matter fraction

   Drag the $\Omega_m$ slider down and up; since the model is flat, $\Omega_\Lambda=1-\Omega_m$ adjusts automatically. With $\Omega_m$ near 1 the curve keeps decelerating, while a small $\Omega_m$ bends it upward — the signature of accelerating expansion from $\ddot a>0$.

3. Compare universes

   Set $\Omega_m=1.0$ (matter only) and then a low value like 0.3, matching today's estimates. Describe how the future of $a(t)$ differs in the two cases, and connect the acceleration to a component with negative pressure, $p_\Lambda=-\rho_\Lambda c^2$.

Simulation

Experiment history

Related physicists

Related library topics