Last week we passed an important milestone in the history of science. November 25th, 2015, marks one hundred years since Albert Einstein delivered his now infamous address to the Prussian Academy of Sciences, during which he laid out the series of equations which lie at the heart of his General Theory of Relativity. This anniversary has been marked by events around the world celebrating his discovery of how the geometry of space and time is influenced by the presence of matter and energy and how this one man and his thought experiments changed the course of science and physics forever.
The theory of General Relativity is one of the pillars of modern theoretical physics and scientific cosmology and for the first time described gravity not as a force, as in the theories of Isaac Newton, but rather as a distortion in the very fabric of space-time itself. The physicist John Wheeler, in an often quoted phrase, summed up the theory when he wrote,
“matter tells space how to curve, and space tells matter how to move.”
One of the outcomes of the equations of general relativity was the theory of the big-bang and how the universe (there could be more than one according to current theories of multiverses) began in a single explosion followed by rapid inflation and expansion.
This explosive event left behind a kind of “afterglow,” a fossil of the early universe, a slowly evaporating entropic clue of those first few moments of time. This energy field has been mapped, in one the most difficult cartographic projects ever undertaken, by the Wilkinson Microwave Anisotropy Probe (WMAP), which was launched by NASA in June 2001, with the mission to make fundamental measurements of the universe as a whole. One of the satellite’s main tasks was very cartographic in nature and sought to create a map of this “afterglow” that would be a kind of “baby” picture revealing the structure of the early universe. A complicated undertaking, the probe looked back in time and mapped the geography of the residual energy left over from the first moments of space’s existence.
The amount of this energy, now known as the Cosmic Microwave Background (CMB), and its distribution is a critical variable in the various theories of the universe’s earliest moments. The results of this “universal” cartographic enterprise (shown in the map below) have complicated the picture of the universe’s expansion. It appears that early on the universe went through a period of very rapid growth, termed “inflation,” when there was an exponential increase in its size. Gradually however, over the last several billion years or so, expansion gradually slowed, as matter began to attract itself together under the pull of gravity as outlined in Einstein’s theory. More recently in cosmological time, data show the universe expanding again at a more rapid pace as the repulsive effects of the mysterious dark energy have begun to be the major actor in controlling the destiny of our universe.
The well-known physicist Stephen Hawking, whose book, the Large Scale Structure of Space-time is a classic in the field, in an interview with New Scientist magazine, said that the results of this map and what they reveal about the distribution of matter and energy (they are the same, all of you remember the E=mc2, from Einstein’s earlier, Special Theory of Relativity) are perhaps the most exciting in his career.
The visualizations of WMAP show a dynamic form of cartography that is far different from the simple paper maps of the past. As computational technology and the speed of spatial computing has increased, mapmakers are finding their way into fields scattered across the entire range of the sciences and the humanities. From earth looking satellites, to big data, to historical studies, to the mapping of Facebook friends and the internet, all the way to large multimillion dollar projects like the mapping of the human brain and the universe as a whole, mapmakers are using complex visualizations as tools of understanding and discovery that are blurring the definition of what a map actually is. The case of the WMAP maps, and the intricacies of Einstein’s theories that they are shedding light on, are just one of the many places that cartography is making its mark and living up to what one of the pioneers in early computer cartography, William Warntz, thought mapmaking would become in the future when, in the 1970s, he wrote,
“We recognize yet another role for maps. In the solution of certain scientific and mathematical problems …that however elegantly stated, are intractable, graphical solutions are possible. […] There are many cases in which the graphical solution to a complex spatial or scientific problem turns out to be a map in the full geographical sense of the term, “map.” Thus a map is a solution to the problem.”