Everyday life on the internet is insecure. Hackers can break into bank accounts or steal digital identities. Driven by AI, attacks are becoming increasingly sophisticated. Quantum cryptography promises more effective protection. It makes communication secure against eavesdropping by relying on the laws of quantum physics. However, the path toward a quantum internet is still fraught with technical hurdles.
To simplify - c is the maximum speed at which a “cause” can be transferred.
If I send a radio signal to turn on a light, and the light will only turn on in response to that signal, the signal cannot travel faster than c otherwise it would not have been able to turn on the light.