Some of the oldest known writings to have survived the ravages of time come to us from China (c. 5,000 BC), and Mesopotamia and Egypt (both c. 3100 BC) . Inscriptions found on steles made of stone, metal and wood survive to this day and have given us a glimpse of, and the ability to know something about, the lives of those people who are separated from us today by the millennia. Inscriptions, carvings, and drawings that adorn the temples, tombs, pottery, and remnants of Greece, Sumer, Somalia, Eritrea, Ethiopia, China, Egypt, Mesoamerica and the Near East lend further insight into those cultures . Some writings have also served as ciphers, allowing us to decode and understand the previously unknowable: with the discovery of the famous inscribed stela, the Rosetta Stone, scholars could finally decipher Egyptian hieroglyphics .
If the simple methods of the ancients—carving, writing, and chiseling by hand on clay, stone, wood or papyrus—strike us as quaint today, we may wish to consider for a moment that those crude methods have also allowed their works to survive for thousands of years. Paleolithic cave paintings in Eurasia are even older, some dating back 40,000 years . Speaking of crude, those paintings were rendered with nothing but pigments made from clay, blood, dirt, saliva, charcoal, bone marrow, and animal fat .
Now consider this: in my closet is an old box of magnetic tapes, the kind we used to play on tape recorders. They have never been physically damaged and yet, after a mere 25 years, most are now unplayable. I also still have a few boxes of VHS tapes. Unless I find a way to convert them to a new medium, they will also be unplayable when my ancient VHS recorder takes its last breath. In any case, many have already started to disintegrate like the tape recordings. All of those recordings will soon be lost, some irretrievably. Old computer files, many still on floppy disks—as well as the old computers able to play them—will likely all be lost when the magnetic medium succumbs or the hardware heads to the graveyard of the obsolete. But it is not just my collection: by the 1980s, the world realized that its film heritage was at risk from the very chemicals that made old films possible, particularly nitrates and celluloids, which were fading and destroying the medium. Despite the ongoing efforts of dedicated preservationists, it is estimated today that ninety percent of all American silent films made before 1929 are now lost; fifty percent of pre-1950 sound films are gone forever. 
So, how certain are we that our descendants, two hundred years from now, will have access to a Blue Ray player? A laptop? A PlayStation? To put it in perspective, today’s school children have never even seen a Sony Walkman, once the pride and joy of their parents (or grandparents!). And how certain are we that electrical current will even power the devices of tomorrow?
If our plethora of recordings today, that vast cornucopia of digital videos and digital photographs that memorialize everything from holidays, birthdays and vacations to family trips, graduations, and sporting events, is not consistently preserved onto new media, it too will all become obsolete and irretrievable—not in thousands of years, but in a few decades. Probably less. In the event of a devastating apocalypse, it is likely that much of our most technologically-advanced media will not survive. And post-apocalyptic survivors may not have access to electricity, let alone the internet or digital devices to open it. Assuming a more optimistic future, even if we were to preserve the current recordings of our culture in a time capsule, it is debatable whether our descendants living 500 years from now would have a way to play it. As it is, today’s engineers know very little about the vacuum tube technology that enabled the early Saturn V rockets to journey to the moon a mere 50 years ago.
We can see that sending information even a few hundred years into the future, such as through a time capsule, poses technical difficulties. The problem lies not so much with providing a basic understanding of the material. We can read a tangible book from two hundred years ago or a stone carving from 2,000 years ago. The real problem is that much of our information today is electronic. According to physicist and information theorist, Dr. Benjamin Schumacher, “Most of the technologies used to store that information won’t last for 200 years.” 
Further, as Brian McConnell states: “Most software today requires the user, or the client program downloaded by the user, to have prior knowledge about the system or information it is designed to access. For example, in order to view a QuickTime video clip, a user has to download viewer software specifically for the purpose of processing and rendering these files. Without the viewer software, the information contained in the .MOV file is unintelligible.” 
This leads to the rather shocking irony that, although humans have never memorialized their lives and their knowledge more fully than they do in the present age, we have never been more at risk of making ourselves completely unknowable to future generations. To that end, we must give serious thought to the idea of anti-cryptography: its most essential goal is “to create messages or programs that can be used by a recipient who has little or no prior knowledge about how they were created. This is a subtle but important difference from the way we do things today.” 
The next irony? As Benjamin Schumacher advises, “For our time capsule, the best bet is to use old-fashioned data storage technologies, such as print on acid-free paper or inscriptions on metal or stone.” 
That said, perhaps some of the simplest—and oldest—methods are still worth keeping around. And taking a fresh look at.
 Bright and Daniels, ed. The First Civilizations, The World’s Writing Systems, Oxford University Press (1996).
 C. Pool, Olmec Archaeology and Early Mesoamerica, Cambridge University Press (2007).
 J. Boardman, ed. The Cambridge Ancient History, Cambridge University Press (2015).
 P. Ghosh, Cave paintings change ideas about the origin of art, BBC News (Oct. 8, 2014). Available: http://www.bbc.com/news/science-environment-29415716.
 Pigments through the Ages. Available: http://www.webexhibits.org/pigments/intro/early.html
 D. Kehr, Film Riches, Cleaned Up for Posterity, New York Times (Oct.14, 2010). Available: http://www.nytimes.com/2010/10/15/movies/15restore.html
 B. Schumacher, The Science of Information: From Language to Black Holes, The Teaching Company (2015).
 B. McConnell, Anticryptography: The Next Frontier in Computer Science, O’Reilly (Feb. 2, 2001). Available: http://archive.oreilly.com/pub/a/oreilly//news/seti_0201.html