Imagine a UFO lands in a football stadium. A humanoid creature walks out onto the field. A television reported breathlessly states, "Finally, proof that we are not alone in the universe!"
Microphones are raised to the creature. He begins, "Sadly, we are alone in the universe. Only humans and aliens exist -- just us two, and nobody else. We are alone."
What does it mean to be alone? Are 4 billion humans not enough for you? How many conscious beings does there need to be for us not to be alone? Enough so that the annihilation of a couple of suns or planets does not wipe out conscious life everywhere?