When I saw this, I wondered whether this was the same Von Neumann who gave his name to Von Neumann probes, which are hypothetical self-replicating spacecraft that can fill the galaxy within a relatively short timespan.
It turns out that this is the same Van Neumann, who appeared to have been very influential in the early days of computing. In reading about him, I was impressed with all the work he'd done. The people who came up with the concept of Von Neumann probes named them after Von Neumann because of his theoretical work regarding how computing machines can self-replicate.
Fermi also used the concept of Von Neumann probes and the lack of alien Von Neumann spacecraft as proof that aliens (or at least interstellar spacefaring aliens) don't exist.
Von Neumann was often considered by colleagues to be the smartest person they'd ever met. There's an old story that goes something like this:
Von Neumann was asked a mathematical puzzle: two bicyclists start 20 miles apart and head towards each other at a steady speed of 10 mph each. At the same time, a fly that travels at a steady 15 mph starts from the front wheel of the southbound bicycle and heads to the front wheel of the northbound one, then immediately turns around and heads to the wheel of the southbound one, and continues until the bicycles meet and he is crushed. What total distance did the fly travel?
The trick is that it seems you'd need to compute an infinite series, figuring out the distance traveled on the first journey, then the second, then the third and sum them all. In fact, you can just realize that two bicycles starting 20 miles away, each moving at 10 miles an hour, will meet in 1 hour; if the fly's traveling at 15 mph constantly during that time, it travels 15 miles.
Von Neumann provided the solution immediately. The man who posed it to him said "Oh, you must have heard the trick already!" "What trick?" said von Neumann. "I just summed the geometric series!"
The way I solved it was to say that the bicycles meet in the middle because their velocities are equal. They travel this 20/2=10 miles with v=10mph in 1 hour. In this 1 hour, the fly will travel 15 miles, no matter how often it changes its direction.
Fermi and von Neumann overlapped. They collaborated on problems of Taylor instabilities and they wrote a report. When Fermi went back to Chicago after that work he called in his very close collaborator, namely Herbert Anderson, a young Ph.D. student at Columbia, a collaboration that began from Fermi's very first days at Columbia and lasted up until the very last moment. Herb was an experimental physicist. (If you want to know about Fermi in great detail, you would do well to interview Herbert Anderson.) But, at any rate, when Fermi got back he called in Herb Anderson to his office and he said, "You know, Herb, how much faster I am in thinking than you are. That is how much faster von Neumann is compared to me."
There are a number of stories about von Neumann, but almost all of them are apocryphal. I do remember his former professors remarking that if they put unsolved problems on the chalkboard, he'd have them solved by the end of class.
Legend has it that when Gödel presented his incompleteness theorem Von Neumann understood that Hilbert's program was destroyed and immediately threw in the towel.
Claude Shannon, arguably one of the greatest electronic engineers of the 20th century (which would be "ever" I guess) even went to Von Neumann for advice. The "novelty" of a signal was thus named "entropy" (inverse thereof) because of how Von Neumann understood information theory fitted into the broader picture of theoretical physics. Entropy = Amount of Disorder in a System = 1 / Novelty, or something like that. Point is, Von Neumann didn't just understand Shannon's ground breaking new theory right away, but also understood how it tessellated with all the other ground-breaking theories of the day.
Von Neumann was one of the greatest mathematicians ever. Theoretical physics, computer science, game theory, statistics, he was a master at everything.
Alternatively, it could be the case that introducing even minor bugs into the programming of your first Von Neumann probe can be a civilization-ending event.
So maybe we haven't seen any probes because they first disassembled their creators for building resources, then became too busy disassembling each other to get very far.
It turns out that this is the same Van Neumann, who appeared to have been very influential in the early days of computing. In reading about him, I was impressed with all the work he'd done. The people who came up with the concept of Von Neumann probes named them after Von Neumann because of his theoretical work regarding how computing machines can self-replicate.
Fermi also used the concept of Von Neumann probes and the lack of alien Von Neumann spacecraft as proof that aliens (or at least interstellar spacefaring aliens) don't exist.