Quora Answer : Which technological innovation will change the world the most by 2042?
All of them.
By which I mean that the network of interactions between the different innovations is phenomenal. And that's the biggest effect of them all : the "internet" if you think of internet as network of networks.
For example, Processing was just a little editor / pre-processor and library to make Java easier for computer artists. But stuck on the front of a free-software compiler tool-chain and coupled with a simple incremental development in micro-controllers, it spawned the phenomenon of Arduino.
Which rapidly led to an ecosystem in which orders of magnitude more people started messing about with electronics and physical stuff. Which led to many people thinking about new kinds of device. (Input and output) And needing to fabricate physical objects.
The Arduino became the brain of the RepRap open-source 3D printer. It became the brain of early quadcopter experiments. (Parts of these quadcopters were 3D printed.) It became the brain of many home-automation experiments, musical instruments, weather-stations, robots etc.
At the same time, the Kinect was introduced as a game controller (with cheap IR depth-perception). Soon hackers were repurposing it to drive robots, fly quadcopters, scan objects for 3D printing etc.
At the same time, Apple's iPhone launched a frenzy of smart-phones, put incredibly powerful computers in everyone's pocket. Those powerful computers drove down the price of Arm chips. Which made it possible for the Raspberry Pi, a small hobbyist board that was powerful enough to run Linux and cheap enough to be bought by a child. Raspberry Pi (and similar boards like BeagleBone) slot right into the Arduino ecosystem.
Soon, many of those tinkerers started professionalizing. Selling kits. Founding startups. Launching projects on Kickstarter and other crowd-funding platforms.
And most of this appeared out of nowhere, since 2000.
At this point, the maker / robotics / internet of things (which is not just about a new way of streaming video to your TV, for fuck's sake) / ubiquitous computing / personal drone etc. cat is out of the bag. What we know is that more people are empowered to dream up, prototype, and crowd-fund new things than at any time in human history. We are beginning to see an explosion of new stuff. Not just mass-produced copies of a few basic patterns, but orders of magnitude more types of things. And at any stage, any combination of two or more of those things can spawn entirely new species will change the world yet again.
So it's the network of networks : of social connections, of information, of ideas, of money, of companies, of types of organization and types of money and types of economy. This is already a world which is utterly transformed compared to just 15 years ago ... most people just haven't noticed it yet.