In November 2008, a paper proposing Bitcoin was sent out to an obscure cryptography list by "Satoshi Nakamoto." On or about Jan. 3, 2009, five years ago Friday, Nakamoto mined the first 50 Bitcoins -- the "genesis block" from which all other Bitcoins have sprung. Nakamoto continued to comment on the development of Bitcoin until 2011 when he appears to have slowly backed away from the project. But Nakamoto almost certainly does not exist -- at least not as an individual named "Satoshi Nakamoto." Most believe the moniker is a pseudonym for the actual anonymous Bitcoin creator -- or cabal of creators.

And since Bitcoin has gained prominence numerous theories have been proposed by journalists and researchers alike. The Switch doesn't purport to offer any answers -- but that doesn't mean it isn't fun to review the speculation. Here are some of the most prominent theories that have cropped up over the years:

Michael Clear or Vili Lehdronvirta. Joshua Davis, writing in the New Yorker in 2011, took a crack at unraveling the Nakamoto mystery. Using a textual analysis of Nakamoto's posting, he settled on Michael Clear -- then a graduate student at Trinity University in Dublin. Clear responded with a joking, "I'm not Satoshi, but even if I was I wouldn't tell you" and has since flatly denied any connection with starting the digital currency and payment system. In fact, Clear pointed him in the direction of Vili Lehdronvirta, a Finnish programmer who studies virtual currencies and who currently is a Research Fellow at the Oxford Internet Institute. Lehdronvirta similarly denied being Nakamoto, in a convincing enough manner that Davis turned his attention back to Clear.

Neal King, Vladimir Oksman, and/or Charles Bry. Adam Penenberg at FastCompany wasn't convinced by Davis's investigation -- in fact, he embarked on his own inquiry. And when he searched for other uses of a particularly unusual term from the original Bitcoin paper ("computationally impractical to reverse") it turned up in a patent application filed three days before the Bitcoin.org domain name was registered. The researchers on the patent, Neal King, Vladimir Oksman and Charles Bry, have all denied being Sakamoto -- but Peneberg wasn't quite convinced. He was particularly skeptical of King's claim that he had never heard of Bitcoin, saying "that would be like a journalist claiming he never heard of Twitter."

Shinichi Mochizuki. Ted Nelson, an information technology pioneer and the inventor of hypertext, speculated that Japanese mathematician Shinichi Mochizuki was Nakamoto in a YouTube video earlier this year. As Chris Mims at Quartz laid out, Nelson didn't have a lot of evidence to back up his reasoning, but he wasn't the only one to come to the conclusion. And not everyone was convinced -- Tyler Jarvis, who went to graduate school with Mochizoichi, said "there is no way he cares about things like Bitcoin" on Twitter when the speculation first started.

Nick Szabo. Just in December the Internet worked itself into a frenzy over a post claiming a textual analysis pinpointed former George Washington University Law professor and current blogger Nick Szabo as the creator of Bitcoin. Szabo was behind "bit gold," a conceptual precursor to Bitcoin, in 1998. But he already denied being the originator of Bitcoin in a blog post in 2011 where he discussed the cypherpunk's intellectual predecessor to the system.

Purported connections to the NSA and Silk Road. Beyond specific individuals, rumors have also swirled that that Bitcoin was related to the government -- specifically the NSA. But no significant evidence has emerged to support that claim besides in a 1996 paper on the possibility of digital crypto-currencies which references research by Tatsuaki Okamoto -- another researcher who is the subject of speculation. At one point, Israeli researchers claimed to have found a link between Satoshi and the Silk Road, citing an early wallet they believed belonged to Nakamato. But the researchers later retracted that allegation after the owner of the wallet turned out to be Dustin D. Trammell, a Texas security consultant.

Anyone have any other good guesses?