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Ever wondered what it would take to bring down the Internet? Well, not much.

Hosted by: Hank Green
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(SciShow Intro plays)

Hank: There's a giant network of machines that contains the sum of all human knowledge and connects us as a species that we have become quite reliant upon. We call it the internet, and it is actually and upsettingly kind of fragile and there are plenty of ways to break it. 

Actually, you might not have noticed, but there were widespread internet outages just last year, thanks to a glitch in what is known as the global routing table, which is basically a map of the internet. Every device connected to the internet has an address, and when you use the internet, you need to send data back and forth between those addresses. But to get to its destination, that data needs to be bounced around to a few different places along the way, and to make sure it gets to the right place, it needs directions. Those directions are stored in the global routing table, and practically every router which redirects packets of data from one network to another uses them. The problem is routers have limited memory, and older ones were only designed to hold 512,000 entries in their maps of the internet, but the internet has gotten bigger than that. 

So in August of 2014, the routing tables finally passed 512,000 routes, at which point older routers registered a memory overload and just stopped working. Basically, the internet broke. Companies developed a workaround by allocating more memory to allow more entries to the table, but at best, it raised the capacity to about a million routes, which only buys us a few years worth of time, and it took a while for everybody to implement the fix, and meanwhile, lots of people lost access to the internet. 

Still, overloading the routing table is something that we can predict and something that we can fix. There are other less innocent ways to break the internet and one of them is incredibly simple: cut the cables. And I'm not talking about the cables in your house, even though that would break the internet for you, I'm talking about the massive lengths of fiber the stretch across the ocean floor connecting the internet across the continents, because, yeah, those exist. We transmit our data the same way we sent overseas telegrams in the late 19th century.

There have been a few upgrades obviously, but the general concept is the same. The good news is that the cables aren't that vulnerable. In shallower areas of the ocean, they're designed to be shark-proof, which makes chopping through them pretty tough, also yeah, we had to make the internet shark-proof. In deeper areas, the cables are so deep that if companies ever need to access them, which they sometimes do for maintenance, they need to use special ships just to haul them up to the surface. 

But there have been times when cable failures have been a problem. In 2003, for example, one group of cables failed twice within a few weeks, mainly affecting the UK, where internet speeds slowed by about an eighth. And as recently as 2013, three people were arrested for deliberately trying to cut the cables providing service to Alexandria in Egypt. There are hundreds of cables throughout the world, though, it would take some real effort to cut through enough of them to cause long-term damage. 

But despite all of our planning and all of our fail-safes, there are still things that are outside of our control. And those things could break the internet for a good long while. Whenever there's a solar flare, for example, the sun sends out lots of high energy radiation, distorting the Earth's magnetic sphere. A huge solar storm has the potential to wipe out important parts of our infrastructure, like the power grid, and without electricity, there is no internet, through really, at that point, the lack of internet would not be the biggest of our problems.

How likely are we to get that bad of a solar storm? Well, not very, thankfully. The last time something of that magnitude hit Earth was in 1859, but electricity was much less of a big deal back then. That storm did knock out some telegraphs, but all things considered, we did okay. But in 2012, we had a very near miss.  The sun sent out a massive flare that would have done serious damage if it had hit us. Luckily, it was pointing in a different direction. 

So barring unforeseen issues with the routing tables, some damaged cables, or a super intense solar flare, hopefully the internet will be sticking around for a very long time.

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