No Stupid Questions

Infrared / line-of-sight based wireless transmission would be the norm.

In reality, a similar scenario happened a long time ago, at the beginning of the cosmos:

In the Big Bang cosmological models, during the earliest periods, the universe was filled with an opaque fog of dense, hot plasma of sub-atomic particles. As the universe expanded, this plasma cooled to the point where protons and electrons combined to form neutral atoms of mostly hydrogen. Unlike the plasma, these atoms could not scatter thermal radiation by Thomson scattering, and so the universe became transparent. (Source)

Before being transparent, "light" would not travel further. The era of recombination, which happened when the cosmos was "merely" 380,000 years old, allowed "light" to travel further. This "light" was also radio wave and microwave, and it was part of the white noise back when people still used analog receptor devices, such as radio receptors and analog TV sets. One could still hear it through analog ham radio transceivers and receptors that are still used today, such as Baofeng UV-5R and RTL-SDR dongles connected to a PC.

In your scenario, EM at the radio range wouldn't propagate, while the rest of the EM frequencies would propagate just fine.

Well, many of the technologies we use in a daily basis are microwave radiation. Access point routers (Wi-fi) operates in the "microwave" portion (2.4GHz and 5GHz), same for Bluetooth. Same for mobile network, which now broadly operates as 4G and 5G. Same for US GPS, Galileo, GLONASS and other geolocating satellital services.

People nowadays use internet to do things. Television and radio became embedded within internet streaming. Governments nowadays use internet to do things. Banks use internet to do things. Commerce use internet to do things. So, they'd be mostly unaffected at the beginning of such phenomenon.

What'd be affected on common people's lives:

• Some types of NFC, so contactless payment would stop working. Non-wireless payments would still work.
• Media broadcasting outside cable and internet. Both FM radio station signals and Digital TV station signals would simply vanish.
• Remotely locking and unlocking cars will become impossible because car alarm sets mostly operates within 433MHz, which is the "radio" part. Cars will probably be "unlockable" physically by turning keys on their door locks, but they will be noisy as they'd be triggered by the lack of signaled unlocking. Everyone's cars would go weeeweeeweeweeeweeeweeweeee... in unison as their owners/drivers resorted to their keys to open the doors. Infuriating for everyone, but not something that would "stop" altogether (except, maybe, for some kinds of alarms that wouldn't allow car ignition to function without proper unlocking, but this is more of an indirect consequence rather than a direct consequence of your "sudden radio wave blackout").

It's beyond common people that things would be more affected:

• Airplanes would stop communicating with TWR and some of their instruments would stop as well. Their comms happen between 108-137 MHz, which falls into the radio portion. They won't "fall from the skies", but accidents would start to happen as the coordination between flights would become impossible and they would need to resort to visual.
• Radars of all kinds.
• Some trains communicate with the railway control using the radio portion. No more switching rails for trains. Possible train wrecking.
• Radio telescopes all around the world (and those in orbit as well) would stop. No more observing the cosmos through radio waves.
• Some of the satellite communications that happen below the microwave range.
• Weather satellites, it would become impossible for them to do their climate-related operations. Weather forecast would become harder to do without this source of info.

It's a multifaceted and complex thing to try and imagine everything that would stop working. Modern society has lots of complex technologies, so I probably forgot something above.

Physics becomes inconsistent and everything explodes. Or the Matrix finally errors out and detaches everyone. You'll wake up and find yourself in some dystopian nursery, embedded in slime.

Well I'd make a ton of money installing bathroom ethernet cables.

It would not immediately be obvious but would have catastrophic knock on effects.

For day to day living the first thing people would notice is their home WiFi stops working and their mobile phone doesn't work at all (calls, mobile data, WiFi). And - as most countries still do it - terrestrial TV broadcasts would suddenly stop (possibly affects rural areas more, many homes in urban centres use cable but obviously this depends on your country). Radio would stop working obviously.

Military-wise it would probably mean immediately going to a state of high alert as a simultaneous loss of communication to many places would be interpreted as an attack that needs immediately investigating. While the military network is resilient and has non-radio ways of communicating it's not expecting to switch to this in an instant and there would be great paranoia about what's actually going on.

All planes would cease being able to communicate with ATC which would effectively ground the entire civilian air space. Instrument landing systems (runway radio beacons) would stop working so all landings would be manual, if the weather was bad pilots would have to divert without being able to check availability with anyone. Clearing the air without radio is a mammoth task and there would almost certainly be accidents as multiple planes try to approach the same run ways, or land on ones that are occupied, or run out of fuel seeing congested runways below and nowhere to go.

Urban rail transit would grind to a halt with drivers losing comms with signal switch stations. Some have non radio alternatives but with every walkie talkie ceasing to work this may not be enough. The network (like the tube and the metro) would halt and slowly manage an evacuation.

There would be general chaos trying to get to work (inc hospitals and other key workers) as RFID security passes stop working and everyone has to be validated manually.

Overall, apart from with airlines, I think the first day it would be inconvenient but not lethal. But then what would follow would be a lot of urban society being unable to function safely. Delivery via air would grind to a halt. Any location requiring security would lock down as security staff would have no way of communicating out of sight unless the place still had wired phones. Governments would immediately be assessing how long their national stockpiles would last without air freight. Possibly highways would get nationalised under emergency government control to prioritise road freight.

China would possibly invade Taiwan. It would be disastrous attempting an invasion without radio but they would probably have calculated that it affect the Americans worse.

Radio is light at a different frequency, because transparency is weird.

It breaks everything if an electron can't change levels and release a photon. Randomly picking one fixated target... fusing hydrogen into helium no longer emits photons and without light pressure to counteract gravity the Sun goes straight to something like a tiny white dwarf.

You can't really say photons only go pow at X frequency and not Y or Z. Photon don't care how you spank it into action. High energy, low energy; photon just wants to fly at the speed of causality.

https://cdn1.byjus.com/wp-content/uploads/2023/03/Visible-Light-Updated-2.png

A lot of stuff would stop working, including stuff like microwaves, satellites, all cell towers, and anything not wired. If it was not magic, it would probably kill everyone as everything is just a spectrum of energy.

Are you planing on breaking physics? If so, could you bring it up a few months.

There are natural sources for radio waves (some stars, maybe other things). Depending on the frequencies that stop, those could be impacted. I expect the energy powering the radio waves would build up. Best case is higher energy emissions, worst they explode.

What do you even mean with "part of the spectrum"? It is all used for radio (except the part that's nearly unusable).

Would you only regard air, or all dielectric materials? Then 'cable' and other networks are down as well.

You don't think a microwave is radio? This post is nonsense

The most people live in the southern hemisphere, India and China. August is winter here.

Radio waves are the same as light, so if radio stopped working the way you envisage, light would too.

Electricity, electronics and electrons are deeply connected with radio waves, so anything electronic would likely cease to function.

Any flying plane with fly by wire would likely crash, traditional linkage type planes would need to land because their engines would cease to operate.

Helicopters would probably auto rotate to an immediate landing.

People would likely starve pretty rapidly, since society is built around electricity.

The phenomenon most like what you describe is called an EMP, Electro Magnetic Pulse.

Radio waves are a pretty big part of the EM spectrum. Do you mean like sudden intense jamming from outer space, or like physics just stops suddenly?

If its the former, its going to depend on what parts of the spectrum are being jammed, but most modern militaries are actually pretty prepared for radio jamming and have alternate systems for most critical applications. The scenario is fairly similar to the EMP saturated environment expected in a nuclear war. The military has spent a lot of time and money preparing to moderate the worst of those effects. Civilian systems would not handle things very well at all. Expect lots of catastrophic cascading failures and instances of permanent damage.

If its the later, all bets are off any time physics breaks.

Edit: thinking about it a little more, I think the biggest risk would be that a nuclear submarine might in interpret sudden intense jamming as evidence that a nuclear war had in fact occurred and decide to fire its missiles when it was unable to contact anyone on any frequency.