If intelligent life does exist elsewhere in the universe, it's possible they will pick up radio signals from us.
gemini://jsreed5.org/log/2023/202303/20230314-extraterrestrial-signals.gmi
Radio signals are a recent phenomena; the "Great Oxidation Event" may have been notable somewhere around 2 billion years ago, if someone had been looking and knew what to look for and could detect the change at however far the light has gone since.
tags #history #geology