I was reading recently about new interest in SETI type programs and got to wondering if life on other (similar) planets could evolve intelligence and then an advanced technological world without the tell-tale trace of radio waves.
Or I guess a similar question could be, how close to our current civilization (cars, computers, etc) could we have gotten without RT? I realize that by default that rules out a large part of the space program but we could still be highly advanced without it couldn’t we? Or would it rule out the space program?
Could there be highly advanced alien civilizations that hadn’t yet stumbled across radio technology?
If we had all current devices, but they had to be wired, the world would look like this.
Realistically, though you could get pretty far without radio. It wouldn’t preclude Space exploration, although it might make satellites a lot less important.
It certainly wouldn’t affect cars, except for entertainment, and other transportation would be minimally affected. Just go back to the 1950’s, and get rid of radio and TV, and you are almost there.
Other transportation would be hugely affected. Modern aviation is pretty much impossible without radio or radar*. Without radio beacons or GPS, aerial navigation is limited to spotting landmarks and dead reckoning. That limits most flights to shorter distances in fair weather. Landing in poor visibility conditions would be much harder and riskier. Ground based radar and radio is also necessary to track and coordinate any significant amount of air traffic. How many planes can take off and land at an airport, per hour, if you can only coordinate everything with signal lamps and semaphore? Basically, aviation would be stuck in a stage not much more advanced than in the 20s: a few small planes operating over short distances, with much lower reliability and safety.
Navigation at sea has also been improved by radio and radar, though obviously it was quite possible before that. However, I have a hard time imagining the development of modern, global container shipping, if navigation was as difficult and hazardous as it was a century ago.
How much of early electronic research and development was tied to the radio? For one example, the origins of modern computers go back to efforts and decrypting radio broadcasts in WW2. There was certainly a lot of development of wired systems and communications networks, though I expect it would be a lot slower without related developments in wireless systems and communications.
*I’m including radar here because (IIRC) the strongest radio-frequency signals emitted by the Earth into space are from high power, tight beam RADAR.
A lot can be done without radio. But once you start playing with electricity and magnetism, radio seems to me to be inevitable. Radio is implicit in the Maxwell equations after all. That doesn’t necessarily mean that radio transmission at the level we do it is also inevitable. Maybe entertainment is not known so no radio stations, no TV, etc. But radio for air navigation doesn’t produce that much stray radiation that is detectable.
Visible light is electromagnetic radiation after all. Understanding of that will lead to radio.
You could also have a society very much like ours, except with no long-range radio transmissions. Think wifi hotspots all over the place, that devices communicate with from perhaps fifty feet away, and which then carry signals on wires or fibers from there. In fact, we might end up having to move to something like this anyway, to alleviate bandwidth crowding.
I guess it depends on whether the OP means radio-qua-radio as in long-distance voice communications, or radio as in any form of efficient long-distance communications. I would think that civilizations would be self-limiting and prone to many disasters without fast, efficient long distance communications of some kind.
As said above, an engineering society just about couldn’t avoid inventing radio unless they never mastered electricity or magnetism. In which case they’re sorta stuck in the steampunk era.
Also, detectable radio is not a sign of an advanced civilization. Within 50 years we’ll have replaced almost all the old fashioned AM & FM radio, and most of the simple radars, with advanced digital waveforms. Which at the limit are almost indistinguishable from noise.
They’ll still be radio in the sense of being EM waves propagating through space. What they won’t be is obviously distinctive and artificial.
Any electrical spark will create ‘radio’ radiation - see the steamships of the 1900-1930 era - those wires strung between masts or smokestacks were radio antennas.
See Wireless Telegraphy
The first issue is the one I mentioned already, that an advancing civilization like ours will be radio noisy for only a few years before going effectively silent again as they move beyond simple waveforms.
That’s sort of sad, but I agree, it seems inevitable - an advancing technological society is probably going to invent radio, but the demand for bandwidth is quickly going to result in the use of compression etc.
So we’re only likely to detect other civilisations by being extraordinarily lucky and looking at the precise right moment, or if they are broadcasting for the express purpose of being seen (e.g. ‘active SETI’).
As a side question; supposing a technological extraterrestrial society on par with our own received one of our digitally-compressed signals containing just one audiovisual stream (and broadcast in such a way that they got the whole thing - including any frequency modulation), with no knowledge of the compression methodology etc - just the conviction that the signal does contain information, what would be their chances of extracting anything useful out of it?
Zero. Properly done signalling is within a fraction of a decibel of the Shannon entropy limit. That means it actually is indistinguishable from pure noise (especially at interstellar distances) unless you have the key.
