Tomorrow, October 21, 2015, is Back to the Future day. It's the date when the characters in the 1985 movie Back to the Future, Part !!, arrive in the future, 30 years ahead.
In the first movie in the trilogy, Back to the Future, Part I, Doc Emit Brown accidentally sends Marty McFly 30 years back to 1955 carrying a 1985 Camcorder. Unable to use the broken time machine DeLorean to get back to ’85, Mary looks up the younger 1955 Doc Brown who marvels at the Camcorder, calling it “astounding, a television studio in a box.’ and is able to hook it up to his 1955 black and white TV. Was that realistic?
The transistor was invented in 1948, and the possibility of integrated circuits was being discussed in the early 1950s. In 1955 TV studios were recording programs on movie film using Kinescope technology. Ampex Corporation sold the first commercial video tape recorder, the $50,000 VR-1000, in 1956, but it is quite possible a know-everything inventor like Doc was already aware of the technology being developed. The video output from the 1985 Camcorder would have been a clearly marked RCA connector. Those connectors date back to the 1940s, when RCA introduced them to allow record players to be connected to radio consoles.
Attaching an oscilloscope to the connecter, Brown would quickly recognize a baseband television signal. It would be in “compatible color” NTSC, but that standard came out in 1953. Television receivers of the time did not generally have a video input, but adding one to a vacuum tube receiver would not be hard at all, a capacitor to the grid of the video amplifier stage would do it. And since NTCS color was designed to be compatible with older black and white sets, it all should just work.
Presumably Mary’s camcorder batteries were not completely discharged and it would be simple for Doc Brown to measure their voltage (if it wasn’t clearly marked on the unit) and hook up a suitable low-voltage DC power supply, or even a battery.
So yes, that scene in the film was realistic.
Now suppose the movie was remade 30 years later in 2015, the arrival year in Back the the Future, Part II. Marty would presumably be carrying an iPhone 6s. What would a 1955 Doc brown have made of that?
Connecting the iPhone to his 1955 TV seems unlikely. The iPhone does not output an NTSC analog TV signal. The video signal it does output was unknown in 1955 and likely too fast for Doc’s oscilloscope to decode. While composite video adaptors are available, there is no reason Marty would have one with him. But of course Doc Brown could have watched the video on the iPhone itself.
Power is a bigger problem. If Marty happened to have a standard USB AC adaptor and Apple Lightning cable, it would plug into a 1955 ungrounded wall outlet, without any adapter. If not, Doc would likely be stumped. The Lightning plug has a chip inside that authenticates itself to the iPhone to prevent cables unauthorized by Apple from working, so there would be no way for Doc to connect external power through that port. The best he could do would be to carefully open the iPhone case, tricky to do without damaging the delicate insides, and charge the battery directly.
In short, while a 1985 Camcorder would be comprehensible to a 1955 inventor, a 2015 iPhone would be darn close to magic. What will 2045 bring? Will vintage movie buffs be able to understand Back to the Future without interpretive notes?
The lesson for computer security: It's hard to predict the future of technology. Long term security requires very conservative designs.