Give consideration to the fact that alien astronomers could have scrutinized Earth for more than 4 billion years without detecting any radio signals, despite the fact that our world is the poster child for habitability.Seth Shostak
Consider: Life arose on Earth close to four billion years ago. Four billion years of slithering, swimming, and soaring life forms. But only in the last 200 thousand years has a species arisen that can fathom the laws of nature and build hardware able to signal its presence.Seth Shostak
We're interested in things that have big teeth, and you can see the evolutionary value of that, and you can also see the practical consequences by watching 'Animal Planet.' You notice they make very few programs about gerbils. It's mostly about things that have big teeth.Seth Shostak
Consider: The human genome consists of about 3.3 billion base pairs. Since there are only four types of pair, that amounts to 0.8 gigabytes of information, or about what you can fit on a CD. With a microwave radio transmitter, you could beam that amount of information into space in a few minutes, and have it travel to anyone at light speed.Seth Shostak
Heads are a good deal, and I think they would be a common feature. It's hard to think of species that don't have heads, although there are some. It's good to have a head because it puts some of the sensory organs - eyes, ears, whiskers or whatever - next to the CPU, the brain.Seth Shostak
Mars still remains the astrobiology community's number one choice for 'nearest rock with life,' but there are many researchers who argue that the moons of Jupiter are better bets. In particular, Europa, Ganymede, and Callisto are all thought to hide vast oceans of liquid water beneath their icy, outer skins.Seth Shostak
It will be the mother of all telescopes, and you can bet it will do for astronomy what genome sequencing is doing for biology. The clumsy, if utilitarian, name of this mirrored monster is Large Synoptic Survey Telescope, or LSST. You can't use it yet, but a peak in the Chilean Andes has been decapitated to provide a level spot for placement.Seth Shostak
Frankly, I'll believe in horoscopes the day I can describe my personality to an astrologer and they tell me what date I was born.Seth Shostak
The usual metric for whether a planet is habitable or not is to ascertain whether liquid water could exist on its surface. Most worlds will either be too cold, too hot or of a type (like Jupiter) that may have no solid surface and be swaddled in noxious gases.Seth Shostak
If the cosmos isn't finite, then far, far away, floating duplicates of your brain - with all its experiences, thoughts, and emotions - are occasionally (and temporarily) thrown together by the random combining of atoms. Such 'Boltzmann brains,' as they're called, are a disturbing consequence of an unlimited universe.Seth Shostak