The original question was: "If you traveled back in time to 1975 equipped with a modern laptop loaded with a development environment of your choice, what's the

The original question was: "If you traveled back in time to 1975 equipped with a modern laptop loaded with a development environment of your choice, what's the first thing you'd do?" There's a big difference between accidentally traveling back in time with only your laptop + dev environment while you're typing at Starbucks and intentionally doing it. If accidental, I don't think the cached text or HTML contents of my MacBook's filesystem would be that terribly helpful in predicting the future (though having modern source code would be interesting, and of course there's the hardware itself). My own knowledge of the last few decades would likely be more useful. If intentional and I have some time to prepare, then I can show up with Wikipedia, stock prices, racing results (Back to the Future got this right), scientific papers, etc. Wikipedia compressed is only ~9GB as of Feb 2014. Perhaps then find some relatives and convince them I'm legit. To offer proof of time travel, describe future events and publish the uuencoded checksums-with-nonce in an NYT classified ad in advance. Both checksums and uuencoding existed in the 1980s and they certainly could have existed on the Unix boxes of the 1970s (maybe they did). Signing with a private key would work after 1976 in the public literature, or 1973 for GCHQ, but would probably be a bit too obscure for easy verification for another decade or so, barring disruption of the timestream.