The whole theory assumes that other civilisations are as wasteful as we are? I doubt any species that is more advanced than we are will be wasting as much energy in the form of light as we do.

And if they dont need light to see or have no eyes?

Good point by Philippe .... it may be life, \"but not as we know it!\" (credits to Spock).

It is equally likely that they will light the dark side of their planet brighter than we do.

David Anderton: Well, lighting doesn\'t really use *that* much energy. Lighting currently represents only a smallish fraction of total electricity consumption globally (and electricity consumption as a whole is itself only a part of overall energy consumption).
When more advanced technologies such as LEDs and such become more widespread, the share of lighting energy of the total can be reduced by an order of magnitude or two without reducing the amount of artificial light.
Also, a considerably more advanced civilization would probably have more energy available (via fusion, large-scale renewables or something else).

Agreed with David Anderton, lol Intelligent life is not wasteful..
Look at all the plants and animals that Inhabit our planet... and you will surely understand what I mean.
Philippe H -- true that they are most likely telepathic

David, why are you assuming they\'d be more advanced than us?

SETI has been around for over 30 years... they\'re searching for radiowaves and such. I could be wrong but I would think that any civilization the was advanced enough to produce artificial light would also be emitting radiowaves of some sort. If a civilization is producing artificial light but not emitting radiowaves then chances are this civilization is many, many years ahead of us technologically and if that is not the case then we could be dealing with a civilization that may not be breathing oxygen.

Radiowaves and now lighting... why not look for motion too? Transportation could show life forms.

re; Dana Lawton
1. Without the genus of Nikola Tesla radio may not have been invented until much later. While Guglielmo Marconi may have invented radio independent of Tesla\'s previous invention he did so using several of Tesla\'s patented inventions.
2. Depending on the planets ionosphere it is possible that they use radio communications intensively without noticeable signal escaping.
3. Edison inc. was not the first to invent the incandescent light bulb it is just history and technology conspired to make his the one you don\'t need to be a historian to remember. and even so there is still other light sources such as limelight, and gas mantle lamps that can light the night sky effectively if the locals are willing to pay the price.