The Pirate Bay's ISP has shut them down
dn.se
dn.se
TL;DR - The were back up 3 hours later but a fiber cut has them down at the moment.
So imagine if all 4 billion computers on the face of the planet requested 1 byte of data from one server. That server would need at least 4 gigabytes/second bandwidth, likely higher, to cope. This can, in theory, be done with a DRDoS attack. This scales quite considerably, considering I have about 1MB/S up-stream bandwidth. If every computer in the world transmitted 1 megabyte of legitimate data requests to a server, its fiber connection would likely melt as it would be hitting 4 petabytes of data.
DDoS attacks usually use fake packets to clog up the server, which then it usually doesn't require too much effort to crash a computer. I'm sure with the 3.6 million registered users that even a small percentage taking part in a DDoS attack could easily take down a server and that's without counting on the use of botnets and such.
The internet works like a bridge; the traffic only runs quickly when there's no congestion in the toll booths. If people start getting out their cars and arguing with the person in the toll booths (fake data packets) it won't take long before you've got delays, which then it won't take long until the traffic comes to a complete halt, which is the time you pray the bridge doesn't collapse! Servers are usually reset after a DDoS and business carries on as usual, however I'm sure that's not always the case.
Yeah! Have you got any idea about what exactly happened? It's kind of crazy if only one person can make that happen.