## anonymous one year ago Why does light travel faster in a vacuum?

1. sohailiftikhar

because their pressure is low.

2. Abhisar

Because, vacuum is optically least dense. understand it like this, your speed of propagation will be less in a path full of traffic (optically dense) and will be high when traffic is low (optically rarer).

3. Michele_Laino

in a medium with refractive index n>1, the light speed is: $\Large v = \frac{c}{n}$ and c is the light speed in vacuum. Now being n>1, we see that: $\Large v = \frac{c}{n} < c$