Our buildings will have fallen, our civilisation will be gone, we will have all disappeared, but we will have left a legacy. In a few billion years there will be little sign that we ever existed. In a far off galaxy, though, all of our broadcasts will still be coursing through space.

We have already reached Ursa Major – the great bear in the northern sky has been listening to crackly broadcasts of voices and music for around two years now. In 19 years it will watch the first pictures, as John Logie Baird's test transmissions reach them. The Berlin Olympics, the breakout of the War, the fall of the Iron Curtain, Rihanna on MTV – it will see it all.

Alderaans not far away, goes the line from the Red Hot Chilli Peppers famous song, but it will be another two years before Californication reaches Canis Minor. The entire band will be dead before their song even leaves the galaxy. It's a little ironic that the solid stone buildings, the visceral possessions that we own are so much more transient, so much more ephemeral than the information that we shoot carelessly through the air, and yet slightly comforting that the thoughts we have, the art we make, the music we dance to and the news that defines our society have such longevity.

Andy Warhol once said that everyone gets 15 minutes of fame. It takes around half of that for the news to reach the closest star – the Sun. In a way, the cheesy sentiment that some dead human 'stars' shine forever is correct. They just shine at a non visible frequency – their faces split into lines and modulated onto radio waves. And it doesn't take much to become one of these 'stars' – the only criterion is that you must have been in some kind of broadcast – you can join the club just by talking on a mobile phone.

It's a little unnerving to know that a million years after we have been forgotten, after the last human has died, that somewhere in the universe an electron will be dancing to the music of Take That; depressing to know that our species will be judged on the merits of the cars that we 'pimped', or the antics of spoilt rich kids in Laguna Beach. We have broadcast much that would be improved by the static of a distant pulsar.

Once we broadcast it, it is gone. The information travels at the speed of light – to overtake it we would have to break the laws of the universe. The electromagnetic vibrations are expanding in a sphere at 300 million metres per second. Eventually they will blend into the static of the universe, muffled by the hum of distant stars, the last echoes of the big bang. Until then, though, they will travel unencumbered through the vacuum of deep space, distorted as the gravity of black holes or distant stars shifts their frequency.

That is the longest lasting physical memory of our species, that is humanity's legacy. So no more shows like 'My Super Sweet 16' please – you're letting our species down.