The best researched chapters are those on medical technology, where there is also deep data and clear dates and names. In other chapters, this depth of detail in persons and dates is missing, and the fact checking has been downright sloppy in places. This gives a slightly uneasy feeling to my reading of the book: what can be trusted at detail level and what cannot?

Some example fact errors:

• The author talks about the Heinkel He 280 being the main German jet fighter in World War II, while anyone versed in technology history knows that that honor befalls the legendary Messerchmitt Me 262.

• There is a claim that Vikings forged swords from carbonised iron which were longer and stronger than those of continental Europe. As a Swede, I have never heard of this fact. I believe the Vikings main military strong point was there fast and shallow-running ships, along with good timing that allowed them to exploit a period of weakness of the European continent.

And I have a suspicion that there are more such minor details which are not quite right in the later chapters of the book.

So overall, a nice concept that should have focussed on a few fewer technologies with more depth.