I am talking about gadgets we see in science fiction movies that obey the laws of physics of our universe and could theoretically be constructed, barring the limitations of materials, energy and time faced by our civilization at the moment.
A Dyson swarm is basically just a huge number solar collectors orbiting the sun. Humanity could put some individual collectors in space if we wanted to, but we don’t have anywhere near enough resources to make a full swarm.
Near-relativistic spacecraft are conceivably possible and are not too far beyond what’s possible with current technology (though would still require significant advancements). The catch is that they would be very tiny and we would have to send a stream of them to their destination.
Retinal projectors are currently under development, and advanced ones could in principle be higher quality than current VR headsets while having a very small form-factor. Optical metamaterials such as metalenses would be very useful for this, particularly if they could be designed to work at all three RGB wavelengths simultaneously (not easy).
Dick Tracy’s communicator watch actually seems pretty shitty by today’s standards. His didn’t have a high def LCD screen in it.
Star Trek’s PADD also seems obsolete by real world standards. Those were just e-readers. A tablet is an entire computer, and a smartphone is an even smaller, pocket size computer. There are even phones and devices that connect to phones that do tricorder like scanning of vital signs, the atmosphere, even analyzing the elements that make up an object through spectrographic analysis. Meaning we have the ability to combine the ship computer, a PADD and a tricorder into one device.
