TV Detector Starships

It's apparently a myth that radio signals from ordinary Earth radio and TV transmitters can be detected deep into interstellar space. It seems rather that it doesn't even penetrate a light year before getting drowned out by background noise. Nonetheless, even a sphere six light months in radius is an enormous volume of space.

What might be happening, however, is that spacecraft may be moving through that volume and detecting BBC television. Nowadays it may be rather more difficult due to it having gone digital, but I feel confident that a Phase III civilisation is more than capable of hacking the signals and turning them into passable video.

Let's do the maths.

Isaac Asimov's 'Extraterrestrial Civilisations' estimates that there are 530 000 civilisations in the Milky Way.

Assuming the Milky Way to be a disc 50 000 light years in radius and 3000 light years thick, and disregarding the nucleus, diameter say 20 000 light years, as unsuitable for life, we have a volume of very roughly 22 x 10^12 cubic light years. This is an over-estimate.

Now suppose each planet has the same number of interstellar flights as Earth has international airliner flights. That's 37.4 million flights per planet per annum, and of course the annum is different elsewhere and there are hundreds of thousands of times the number of potential destinations, so this is a huge underestimate too.

Hence it's not unreasonable to assume that there are over 20 x 10^12 interstellar journeys a year in this Galaxy.

Now divide the volume of the inhabited Galaxy as calculated above by that of a sphere six light months in diameter, which is around half a cubic light year. So that's 44 x 10^12 times the volume of the sphere in which it's possible to receive BBC TV signals. That means that if every alien craft is watching TV from nearby planets, it ought to happen about once every two years, assuming the distribution of flight paths through the Galaxy to be random.

However, there could be hundreds or thousands of passengers on board the offending starships, and not one of them has a TV licence. What they probably do have, though, is equipment capable of receiving TV signals. Given that we have mobile phones even now, there will be many of those aboard each starship. Therefore we only need one such starship to pass through our local volume of space to generate a reason to fine hundreds or thousands of aliens.

So, my suggestion is to launch a fleet of TV detector starships to patrol the space around the solar system and pick up the signals from craft passing near us so the TV Licencing Authority is motivated to make first contact with spacefaring civilisations and fine them accordingly. These fines can be used to finance the BBC space programme.