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“Visualization gives you answers to questions you didn’t know you had”*…

Reckoning before writing: Mesopotamian Clay Tokens

Physical representations of data have existed for thousands of years. The List of Physical Visualizations (and the accompanying Gallery) collect illustrative examples, e.g…

5500 BC – Mesopotamian Clay Tokens

The earliest data visualizations were likely physical: built by arranging stones or pebbles, and later, clay tokens. According to an eminent archaeologist (Schmandt-Besserat, 1999):

“Whereas words consist of immaterial sounds, the tokens were concrete, solid, tangible artifacts, which could be handled, arranged and rearranged at will. For instance, the tokens could be ordered in special columns according to types of merchandise, entries and expenditures; donors or recipients. The token system thus encouraged manipulating data by abstracting all possible variables. (Harth 1983. 19) […] No doubt patterning, the presentation of data in a particular configuration, was developed to highlight special items (Luria 1976. 20).”

Clay tokens suggest that physical objects were used to externalize information, support visual thinking and enhance cognition way before paper and writing were invented…

There are 370 entries (so far). Browse them at List of Physical Visualizations (@dataphys)

Ben Schneiderman


As we celebrate the concrete, we might carefully-calculated birthday greetings to Rolf Landauer; he was born on this date in 1927. A physicist, he made a number important contributions in a range of areas: the thermodynamics of information processing, condensed matter physics, and the conductivity of disordered media.

He is probably best remembered for “Landauer’s Principle,” which described the energy used during a computer’s operation. Whenever the machine is resetting for another computation, bits are flushed from the computer’s memory, and in that electronic operation, a certain amount of energy is lost (a simple logical consequence of the second law of thermodynamics). Thus, when information is erased, there is an inevitable “thermodynamic cost of forgetting,” which governs the development of more energy-efficient computers. The maximum entropy of a bounded physical system is finite– so while most engineers dealt with practical limitations of compacting ever more circuitry onto tiny chips, Landauer considered the theoretical limit: if technology improved indefinitely, how soon will it run into the insuperable barriers set by nature?

A so-called logically reversible computation, in which no information is erased, may in principle be carried out without releasing any heat. This has led to considerable interest in the study of reversible computing. Indeed, without reversible computing, increases in the number of computations per joule of energy dissipated must eventually come to a halt. If Koomey‘s law continues to hold, the limit implied by Landauer’s principle would be reached around the year 2050.


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