The appearance of new technologies suddenly is rather rare. By `sudden' I do not mean the appearance of a working new technology `out of the blue' as it were, with no warning whatsoever. I do not know of that ever happening. (Does anyone else know of such an appearance?)
What I mean is the public display of a new technology that is fairly mature but more successful than anyone expected. What is required is a technology, at least somewhat known, that provides a `shock of the new' to a wide range of people.
I think the display of the first Xerox copying machine qualifies. Even though many people had invented and displayed technologies for rapid copying, the Xerox machine was simpler and faster.
The first computer spreadsheet also qualifies.
I can think of four technologies that might do the same in the future. But first my memory of the past century:
It is arguable that the machine gun and tank of World War I were as influential as the nuclear bomb. But machine guns did not provide the same `shock of the new', except to elderly generals. Moreover, initially, tanks failed miserably, mainly if I remember rightly, because they were misused.
Thinking back over the past century, I cannot think of other great examples. I am sure others exist, but these are what I remember. (Please tell me of others.)
Consider other technologies of the past century that have became well known and influential:
(My mother told me that of all the inventions since 1900, she thought the vacuum cleaner the most significant. For cultural reasons, I had not thought of it.)
None of these technologies appeared `suddenly'.
It is true that some of these innovations changed how people thought to act in a fairly short time. In the late 1950s and 1960s, for example, airliners changed how people traveled from one city to another in the US. In the 1980s, personal computers came to be used as `super-typewriters', and in the 1990s, people began to use the generation-old Internet.
In France, over a few years centered around 1910 or 1912, buses and trucks powered by internal combustion engines replaced their horse drawn equivalents, even though private automobiles as such did not become important until the latter part of the century.
But none of these changes were quite as surprising as those I mentioned.
As for the future:
I can think of four technologies whose display would surprise many, even though they have been discussed and investigated for decades:
Probably the rocket engine would have to be `air-augmented'. (A nuclear thermal rocket engine might also work, but it would likely release too much radiation for widespread use.)
An earth to orbit rocket that is inexpensive to operate would not be designed and developed by any private group. This is because its investors' accountants could see that competitors would soon duplicate the process and reduce profits. Moreover, the governments of the major space-faring countries and coalitions have no interest in lowering the cost of intercontinental weapons, which this action would do. The US, for example, is not going to make it less expensive for Iran to threaten the US directly.
Much money has been invested in hydrogen fusion research over the past few generations. It is known that humans can cause fusion; after all, that is what a hydrogen bomb is about. The key is to generate energy more slowly than in a bomb.
The effort is difficult. That is the stated reason we do not as yet have a hydrogen fusion reactor. But some say the reason is that most of the money has gone to research the wrong technology, that of tokamaks. Others say that with an in improvement super-conducting magnets, a tokamak or other design would work. Some say the effort is simply difficult.
I do not know what is true. But let us suppose that humans could build a successful hydrogen fusion reactor.
In that case, we know that powerful interests would be against its deployment in the near future. That is because a not-too-expensive hydrogen fusion device would lower the value of huge, long term investments in coal, oil, and natural gas. It would change international politics dramatically. It would weaken the current government of Russia. It would bring unknowns.
As far as I can see, the only country with the knowledge and the motivation to fund hydrogen fusion development is Israel. That country sees that it would benefit militarily if it could synthesize oil at a lower cost than any Arab oil producer can pump it. Such a price cut would reduce the power of its enemies.
China has the motivation, since it suffers serious air pollution from burning indigenous coal and must also import vast quantities of oil. I do not know whether it also has the ability to apply knowledge and the daring to fund a project that may well fail.
Europe should have the motivation, since it is dependent on foreign sources of energy; and it has the knowledge (presuming, as I said, that the effort would succeed without the expense and time required by the current ITER project). But as far as I can see, Europe lacks the willingness to invest.
We already have humanly-built Von Neumann machines. They are called `economies'. The fastest reproduce themselves in seven years. (Such a growth rate is 10% per year. That pace of development has never lasted more than a generation or two.)
I am thinking of a humanly-built Von Neumann machine that can reproduce itself every seven months or every seven weeks. I cannot conceive of a current industrial system that could become like that. Something new is required. For success, investors would have to invent and build robots or nanotechnology self-assemblers. Rapid replication is `robot manufacturing' at speed.
A side effect of rapid replication is that all previous manufacturing facilities become obsolete. Besides reproducing themselves, well designed Von Neumann machines could manufacture all the objects that people want. The result is that people could become richer in objects, but not in goods like `location' that cannot be manufactured, and not in services (except for those services provided by robots, such as automatic answering machines).
Unless their governments invent and control `rapidly' reproducing Von Neumann machines, China and Japan would suffer particularly, since those countries, along with the smaller countries of Asia, depend on manufacturing exports.
Von Neumann machines have been discussed since Von Neumann first proposed them in the 1950s. While natural Von Neumann machines, such as bacteria, require a megabyte or two of `source code' — their DNA — a NASA study of the early 1980s suggested that a humanly-built Von Neumann machine on the moon a might require 10 or 100 gigabytes of source. A less flexible and less complete humanly-built Von Neumann machine on the earth might well require less code. But in any event, the effort would be large.
I do not know of any work being done directly to implement humanly-built Von Neumann machines and cannot imagine who might fund the development, even though it is, as far as I know, possible and would be, I think, of value to humanity as a whole.
This is commonly called `artificial intelligence', but I do not see that `intelligence' as such is needed. An `artificial stupid' need not be confusable with a human; it does not have to be able to pass Turing's test of intelligence.
Instead, such a computer, or robot, needs to be able to the few things that humans most frequently want it to do, and also — and this is key — be able to do the many things that humans infrequently want it to do. The computer or robot cannot require too much expertise on the part of humans. In this case, `not too much' means no more than the learning required to drive a car or to read and write. In other words, an amount of learning that can be expected of everyone, not just of experts.
I do not know of any work being done directly to implement such computers.