Is anybody out there?

But despite these concerns, for the moment, the plans for deliberate transmissions from Earth go ahead and there is nothing anyone can do to stop them - or even demand a discussion beforehand.

One thing is clear from our searches for ET - there is nobody transmitting strong interstellar beacons in our local vicinity. If "they" are out there, they are keeping quiet, prompting the question that they might know something we don't.

Perhaps the aliens already know about us and are on their way. Or perhaps not. Intelligences - possibly vast, cool and unsympathetic - could be sweeping their skies looking for us. At the moment when they point their instruments in the direction of our sun - a commonplace yellow-dwarf star - they may well find nothing unusual, if no one's sending messages in the other direction. Should we keep it that way?

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