"Another view to the same ETI problem presented by Jet Propulsion Lab and CalTech in <a href=""https://arxiv.org/ftp/arxiv/papers/2012/2012.07902.pdf"">https://arxiv.org/ftp/arxiv/papers/2012/2012.07902.pdf</a>:<br><br>"The results of our model yield a range of possible quantities for intelligent life over time. We<br>assert that the intelligent life will always be most abundant approximately 4 kpc from the galactic<br>center", peaking at time around 8 Gyrs, decreasing monotonically from that peak point," and that a<br>majority of potential intelligent life is still young. The exact number of the intelligent life estimated<br>here is not the focus of our work; rather", it is instead the development of a statistical,"<br>comprehensive galactic picture tracing the potential growth propensity of intelligent life over a<br>course of ~20 billion years. ""