# Planck length and the speed of light

1. Dec 18, 2009

### helenk

How can the Planck length and the speed of light both be universal constants? Will the Planck length change depending on your frame of reference?

:)

2. Dec 18, 2009

### rhenretta

Planck length is based on 3 constants, none of which change due to speed

$$\ell_{p}=\sqrt{\frac{\hbar G}{c^3}$$

Since $$\hbar$$ , G, and c are all constants, planck length also remains constant