How advanced are we as a civilisation?

How might we find evidence for a civilisation on the Kardashev scale?

Looking for Type 1 civilisations

Over the last decades, astronomers have been able to predict the existence of dozens of planets orbiting various stars outside our solar system. Much of this work is done by observing the ‘wobble’ of a star. Planets will cause their parent stars to ‘sway’ as both planet and star are actually both revolving around a common centre of gravity which is not in the middle of the star. Another method used is to measure the light from the star dimming as a planet passes in front of it.

In 2005, astronomers confirmed that they have produced an image of a planet five times the size of Jupiter orbiting a star 200 light years away from us. As you can see in the image, the planet is a fuzzy orange ball. Telescopes will have to be far larger than those which exist today in order to produce an image of oceans, land and cities.

If ET lives on a planet orbiting a distant star and has invented something like television or radio, then radio telescopes may pick up these signals. A strong collection of radio waves which continue over time may be our best way of finding a Type 1 civilisation. SETI, the well known Search for Extraterrestrial Intelligence is well known for searching for signals of this type. Powerful and persistent radio signals are most likely our only currently available method to spot an extraterrestrial Type 1 civilisation.

Looking for Type II civilisations

Kardashev’s scale indicates that civilisations of this type have been able to harness the power of a star – presumably the one around which their species originates from.

One way of doing this was proposed by physicist Freeman Dyson in 1959. Dyson suggested that perhaps a civilisation advanced to a sufficient degree could break apart the planets in their solar system and use the material to form other ‘island’ habitats orbiting the sun in a ‘swarm’. This would allow much, much more of the energy from the star at the centre to be used than what could be gathered on the surface of a planet.

These ‘Dyson spheres’, as they are commonly and inaccurately called, would most likely appear to have odd peaks of radiation and brightness as the sun they surrounded would be visible periodically when the swarm of islands orbiting it passed through our line of sight.

Again, radio telescopes could spot a Type II civilisation which had constructed a gargantuan structure of this kind around a star – as well as astronomical telescopes.

Looking for Type III civilisations

If Dyson spheres hinted at science fiction, then Type III civilisations which utilise the power of an entire galaxy will remove all doubt. If ET has had enough time to travel thoughout his home galaxy then perhaps we would find hundreds or millions of radio signals or the tell-tale flickerings of Dyson spheres. Or perhaps on a more precarious limb of speculation, civilisations of this magnitude would have learned how to draw power directly from more energetic phenomenon such as black holes or pulsars.

Possibly the biggest problem facing any serious effort to locate an extraterrestrial civilisation is the size of space – and the scale of time. At the most extreme estimate human beings on earth have only organised themselves in cities over the last 8000 years. We have only had radio communication during the last hundred of those years – and the tiny signal from our earliest radio and television communications would have only radiated out less than 100 light years from our solar system in all directions. As our galaxy is a disc about 100,000 light years wide and 1000 light years thick, any creatures looking for us would be practically our neighbours. The nearest galaxy to us, Andromeda is 2.5 million light years away – others are much further.

Where is human civilisation on the Kardashev scale?