Why is knowledge doubling no longer used as a metric to converge on the limit of the singularity? If we go back to Buckminster Fuller identifying the the "Knowledge Doubling Curve", by observing that until 1900, human knowledge doubled approximately every century. By the end of World War II, it was doubling every 25 years. In his 1981 book "Critical Path", he used a conceptual metric he called the "Knowledge Unit." To make his calculations work, he set a baseline:

- He designated the total sum of all human knowledge accumulated from the beginning of recorded history up to the year 1 CE as one "unit."

- He then tracked how long it took for the world to reach two units (which he estimated took about 1,500 years, until the Renaissance).

Ray Kurzweil took Fuller’s doubling concept and applied it to computer processing power via "The Law of Accelerating Returns". The definition of the singularity in this approach is the limit in time where human knowledge doubles instantly.

Why do present day ideas of the singularity not take this approach and instead say "the singularity is a hypothetical event in which technological growth accelerates beyond human control, producing unpredictable changes in human civilization." - Wikipedia