At times from arduous research, at other times from serendipity, and sometimes from opportunism, moments of human ingenuity strike to forever change the face of history. The following four technologies are among the most prolific.

The printing press (1439)

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Littered within the marginalia of medieval texts are countless hand-drawn illustrations by monks who transcribed manuscripts entirely by hand. Many of these drawings were non sequitur, sometimes even vulgar. The reason? The monks were amusing themselves as transcribing tomes is tedious work. Moreover, transcription was expensive. Outside of monasteries, literacy was confined to nobility as most couldn’t afford to purchase literature to read.

All of this was bound for change at the hands of a German entrepreneur. By the 1400s, the basics of print technology had been developed in the form of a wooden block with engraved letters that was covered in ink and stamped onto paper. Eager to find an edge and make a buck, Johannes Gutenberg built upon the design of earlier print technology by replacing wooden blocks with individual metal pieces that could be rearranged in a frame. Thus was born moveable type. When Gutenberg developed the printing press, it was operated by hand. However, even with the required labor, the printing press allowed for the mass production of text on an unprecedented scale.

Early on, nobility viewed printed texts as cheap imitations of authentic hand-transcribed texts, which shifted the early market of printed texts to the middle and lower classes. The widespread availability of literature along with the growing middle class fueled literacy rates among the public. It accelerated The Enlightenment, powered higher education, and eventually facilitated an environment in which democracy could one day flourish.

The electric dynamo (1831)

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Observations of static electricity trace all the way back to 600 BC with the Ancient Greeks. However, it wasn’t until millennia later that tangible progress was made in describing the forces at work. By 1600, William Gilbert coined the word “electricitus” from Latin to refer to observed electrostatic forces. Looking into his work years later, Thomas Browne referred to the forces as electricity, and, in 1752, Benjamin Franklin demonstrated that static sparks and lightning are part and parcel of the same phenomenon.

The first major breakthrough in harnessing electricity came from the Italian physicist Alessandro Volta. Volta invented the voltaic pile, the world’s first functional battery, which was able to produce a steady current and a flow of electric charge. Volta’s experiment was instrumental to technological progress, but it wasn’t until the advent of the work of Michael Faraday that electricity became a viable and widespread source of energy. Faraday invented the electric dynamo, which used a copper coil and a magnet. Building upon his design, Thomas Edison and Joseph Swan developed the incandescent bulb.

As romantic as candlelit dinners may be, burning the midnight oil wasn’t ideal for productivity. By the early 1900s, continued developments led to the widespread commercial use of electricity.

Penicillin (1928)

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“I breathe, therefore I am” doesn’t have quite the same ring to it. It was, however, an unfortunate reality in the case of René Descartes’ fatal case of pneumonia. Descartes was one of countless men and women who significantly influenced history but were lost to illness.

Returning from a vacation in Scotland, Dr. Alexander Fleming returned to his bacteriology lab to find a mess and a poignant surprise in the form of a mold. Writing in his journal, Fleming recounts:

“When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer. But I guess that was exactly what I did.”

Fleming observed that the mold had prevented the normal growth of Staphylococcus aureus on his petri dishes, and so went the discovery of penicillin. It wasn’t until the 1940s that Fleming’s discovery was acknowledged, and production of antibiotics began in earnest, but once the ball was in motion, the face of modern medicine was forever changed. Innumerable lives have been saved by the advent of antibiotics. It’s impossible to say what the world would look like without Fleming’s serendipitous discovery, but widespread over-prescription and poor patient compliance continues to fuel antibiotic resistance among bacterial populations in both the developed and developing world.

ARPANET (1969)

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There are quite a few steps in between the invention of the light bulb, penicillin, and the internet.  However, it wouldn’t do justice to a list of world-changing technologies in the information age without including the innovation that has defined our own era.

The U.S. Department of Defense began funding for the Advanced Research Projects Agency Network (ARPANET) in the 1960s. The goal was to use packet switching, an innovative method of data transmission, to establish a communications network for rapid exchange of information. ARPANET was the first of its kind and, importantly, the first to use Transmission Control Protocol (TCP) and Internet Protocol (IP), or “TCP/IP” for short. TCP/IP standardizes packet switching, allowing for widespread expansion of the network. The technology developed in ARPANET was used to develop several more networks within NASA, the NSF, and the DOE. By 1974, NSFNET was linked with ARPANET and provided the foundation upon which the internet was built.