Ken Ham: "Stop sciencing, astrophysicists! Aliens are hellbound!"

[Anomalocaris]

Don't worry, we won't find any. Earth like planets are far too rare, and even if you have one evolution does not veer towards intelligence but rather away from it as brains are energy expensive. Yes I'm aware of the kepler finds but we have no way of knowing if those worlds have the liquid core needed for life to evolve.

If our understanding of planetary formation and galactic evolution is anything close to being right, then all rocky planets with simular age as earth and same or larger size as earth, and formed in similar surrounding in dust rich spiral arms of milky way, are extremely likely to have still have liquid cores. The reason is they formed sufficiently late in the evolution of Milky way such that their formation nebulas would include substantial percentage of long half-live raioactive isotops, and these would be included in the planet to form a strong, durable heatsource in the core. At the same time their size would provide the insulation and relatively low surface area to volume to enable them to retain heat well enough to keep their core molten for >5 billion years.

Also, liquid core is probably not necessary for life. It is now strongly suspected that most primitive, as well as most common form of life on earth, and probably throughout the universe, are extremaphiles that can exist underground under high temperture and harsh chemical conditions. These forms of life can exist even if a planet is not protected by any form of megnetic field. Complex, intelligent life might be hard to develop in these situations based on our current understandin, but our understanding of what conditions are needed for intelligence to evolve is sketchy anyway.