What would happen to the Internet if all computers crashed?

No, sorry, the internet is a bunch of wires and fiber cables and routers.
The data exist at the endpoints, in those devices that would be destroyed.
They’re not in the wires or routers, except for tiny sets of buffered bytes if those weren’t destroyed too.
We’d have to re-invent the Harlem Shuffle on our own.

The Internet is much more vulnerable to attack than most people realize. If you look at the number of connections that Internet nodes have, it follows a power law distribution. What this means is that a relatively small number of computers are responsible for the bulk of the traffic. Power laws are fairly common. Wealth distribution and the sizes of cities are other examples Taking down a relatively small number of nodes would cripple the flow of data just as bombing a small number of a country’s cities would decimate the country’s population.

@LostInParadise The internet, in particular the protocols on which it is built TCP/IP, are designed to be very robust. Traffic will be routed around broken links automatically as long as there might be a way to relay to the destination.
The first Gulf War (Kuwait, Bush Sr.) was complicated by the fact that the Iraqis were using vanilla internet technology to communicate. When a target site was blown to bits any Iraqi military communications that might have flowed through it went around it instead.

The OP said “all devices” so I answered from that perspective.

Once we get everything there is about us into Google et al, and let our books and pictures crumble to dust, then we are vulnerable to the disappearance of civilization and culture if the power goes out.

They won’t. Why waste time speculating?

Your question assumes that the data are all “floating around” somewhere right now. That’s not how it works. Your data is stored in specific locations, in specific machines, even if you don’t know where all of them are, and even if they’re not all together. So, if all the devices that allow us to get on the internet (by which you seem to mean all computers) are destroyed (and I mean really destroyed), then the data are destroyed with them.

Your multiple question marks seem to indicate that you are very concerned about this possibility. I don’t think that it’s reasonable to worry about all the computers in the world being destroyed, but there are reasons to worry about losing data if you are storing it outside of hard drives that you own and have physical access to. If you are worred about this, then keep backups.

It depends on how much of the internet’s data is backed up on physical media like magnetic tape.

@dabbler , The protocols are robust with regard to random outages. If the major hubs like those of Google were attacked, the flow of data could be seriously diminished.

Isn’t the destruction of internet systems one of today’s international threats? If the grids(?) are destroyed, all the communication abilities would be useless? I ask out of ignorance.

There are ways to mess with portions at a time, we see reports of DoS denial-of-service attacks with specific targets. And the internet portion we use the most, World Wide Web has it’s own vulnerabilities especially DNS service that determines the real addresses of the URL domains with the web sites we visit. There can be pockets of malfunction and outage but the flow goes on in as much of the internet as possible by what routes it has to. Functionally, national firewalls in China and other countries look like malfunctions and the system tries for alternatives which are sometimes successful.

There was a worm in the 80’s that came close to taking down most of the internet by infecting servers in ways that are now prevented. Who knows how creative disruptive forces will get in the future. If our world continues getting more corporatist, I suspect overt global corporate warfare will take place over networks before they start shooting missiles at each other’s headquarter buildings. But they will have to be careful of collateral damage or risk losing customers.

Frankly, I think it’s hard to tell by what mechanism humanity will avoid becoming like William Gibson’s dystopias. The complexity we build will have challenges that rival those of nature.
In five hundred years will it be some mashup of ‘Mona Lisa Overdrive’, ‘The Fifth Element’ and ‘Idiocracy’ ?