[yefragetuwrabrumuy]

There are some common sense rules of thumb about life in the Milky Way. To start with, create a timetable for it that is 14.5 billion years.

The first 4.5 billion years are pretty much lost because the galaxy was in a formative period, and its first stars had yet to start exploding and forming metals in the process, and the overall galaxy was very irradiated and “hot”. So the actual life formation on planets that *could* be habitable probably started around 10 billion years ago.

Based on the history of Earth, it took about a billion years for basic one-celled life to emerge. Earth might have been helped by a bombardment of metals from a nearby supernova, also possibly by the Theia object, increasing its mass and possibly giving a lot of metals to Earth.

[Windflier]

There are some common sense rules of thumb about life in the Milky Way. To start with, create a timetable for it that is 14.5 billion years.

In time, I believe that scientists are going to revise that number upwards, again and again. It's my opinion that the known universe is much, much older than people currently believe it is.