The velocity of light in vacuum, c, is approximately 3 × 10 8 m s −1, fast enough to make 7.5 round-the-world trips in a single second, and to move a distance of 300 mm in 1 ns. This ultrahigh speed ...

A simple and budget-friendly soup that freezes beautifully. Make it extra special by drizzling with a little cream and scattering chives or parsley on top. Serve with warm crusty bread and butter.

Slow light is an electromagnetic wave with a group velocity reduced by optical resonances in the medium through which it is travelling. These resonances can occur in atomic vapours, in photonic ...