## Wednesday, November 6, 2013

### natural scale of the Universe

can you express the Universe's current

• age $1/H_0$
• size $c/H_0$
• density $\rho_\mathrm{crit}=3H_0^2/(8\pi G)$
• temperature

in Planck-units?

#### 1 comment:

1. the size $c/H_0$ of the Universe in units of the Planck length $l_p = \sqrt{\hbar G/c^3}$ is $\simeq 10^{61}$, the age $1/H_0$ of the Universe in units of the Planck time $t_p=l_p/c$ is again $10^{61}$, the Planck temperature $k_BT_p = \sqrt{c^3\hbar/G} = 10^{+32}$ Kelvin, and about $10^{32}$ times above the current temperature of the Universe, and the Planck density $\rho_p= m_l/l_p^3$ with the Planck mass $m_p = \sqrt{c\hbar/G}$ is $10^{122}$ times larger than the current density.