A paper has recently been published that takes all the present theories about the ways in which life can arise on a planet, mixes in the known properties of planetary systems including all seventy-nine known transiting exoplanets and looks to see how many actually do rule out the possibility of life and how many don’t display such destructive behaviour. The answer is that two systems violate all known principles for getting life going and seventy-seven aren’t obviously sterile. This doesn’t mean there is life in these systems, just our present theories and observational data can’t rule it in or out at present. Similar with the other two, it is simply that present theories don’t provide a way for life to exist there.
By life, the researchers mean stable Earth sized planets in the habitable zone for a certain length of time. In two cases, the hot Jupiters in the system would’ve definitely thrown an Earth like planet out of the system, in a further twenty-eight there would’ve been some history of destabilisation but later relaxation into a more habitable rhythm. This means that although the presence of hot Jupiters has often been suggestive of a galaxy full of mostly sterile solar systems, it may happen to not be that way. More details at Astronomy Now.
Astronomy Now also have this report on the energy cost of running an interstellar beacon blasting out a signal for aliens to spot – the kind of thing the ‘Wow’ signal was meant to represent. The trouble is the kind of energy required for the kind of signal sent over the kind of distances between stars is rather a lot and could run counter to the repeatability principle of the various SETI studies – that for a signal to be validated, it must be repeated. Close by aliens may be able to put out a low resolution signal, beamed like a lighthouse around their entire celestial sphere, but a little farther away and it may just be a little too much.
…using our kind of technology that is…