It's also such a universal constant that some sci-fi stories or movies (eg, Contact (1997)) use them as a tool to indicate an intelligent civilisation. In other

It's also such a universal constant that some sci-fi stories or movies (eg, Contact (1997)) use them as a tool to indicate an intelligent civilisation. In other words, transmit 2 blips, 3 blips, 5 blips, 7 blips, and it soon becomes clear it's not random - it's a list of primes.