[Physics] the error in the measured value of the Hubble Constant

Question

I've found on the internet that the Hubble constant has been measured to be about $2.3\times 10^{-18} \, \mathrm{s}^{-1}$ Does anyone know what the current error bounds are on this value?

Answer 1

The Hubble constant, $H$, has been measured by many experiments. One of the most recently published measurement by the ESA Planck Surveyor indicates,

$$H\approx 2.20 \times 10^{-18} \pm \underbrace{2.50 \times 10^{-20}}_{\text{uncertainty}} \, \, \, \, \, \text{s}^{-1}$$

or equivalently in more common units (for the Hubble parameter),

$$H\approx 67.80 \pm 0.77 \, \, \frac{\text{km}}{\text{s}\,\text{Mpc}}.$$