Buckle up, readers. Today we’re going on a speed trip through the universe. We’re starting with a salute to a very remarkable woman, someone who reached for the stars during her lifetime, and who died on Christmas at the age of 88. Her name was Vera Rubin, and she was an astronomer. I paid particular attention to her story because one of my earliest ambitions was to travel to and study distant planets. My life took a different direction, but I am still an avid reader of news stories about that field.
During her lifetime Dr. Rubin was denied even a course catalog from Princeton, which did not admit women to the astrophysics program. She had to consult with a famous astrophysicist in the lobby of a building because women weren’t permitted in the offices upstairs. She had to fight for access to the Mt. Palomar telescope. Yet despite the obstacles in her path, she transformed modern physics and astronomy with her discovery of dark matter. (She never received a Nobel Prize for her work; many women in the sciences think this was because of her gender.)
What is dark matter? We don’t really know. It doesn’t emit light or other forms of radiation. We can’t see it or detect it with our instruments. But it has mass that affects the motion of everything else in the universe.
Bear with me while I throw some inconceivably large numbers at you:
This past October, The Astrophysical Journal reported that there appear to be ten times as many galaxies in the universe than had previously been estimated. The new number is two trillion (2,000,000,000,000), and that’s considered a low estimate. Each galaxy is estimated to have about 100 billion stars. And nearly every star has one or more planets, plus a profusion of items too small for our instruments to detect: moons of those planets, asteroids, and comets. (OK, your head is spinning. So is mine.)
Prof. Rubin calculated that everything, everything we humans can see or detect—all those trillions of galaxies, all of those stars and their planetary entourages—is merely five percent of what actually exists. Another 27% is dark matter—matter that does not emit light or energy. We know almost nothing else about it. The rest of what’s in the universe, Dr. Rubin speculated, is dark energy, about which we know even less.
We are very small, short-lived creatures, like blind worms in a cave, struggling to comprehend our environment with our limited sensory equipment. But we do struggle.
For millennia we have looked up and tried to explain what we saw. Various nations worshipped the sun and moon as deities, and interpreted heavenly events as omens. The Hebrews said God placed these bodies in the celestial firmament (conceived of as a solid arch overhead) to shed light on earth. The Greeks spun legends of heroes transformed into constellations. Gradually we replaced myth with something closer to what we think of as science. By the time in which my novels take place, the 9th Century BCE, the educated elite had learned to predict eclipses and realized that these were natural phenomena and not messages from the gods. (Two of my characters, Arzeh in The Throne in the Heart of the Sea and Arneb in The Stars in their Courses, are mathematician astronomers.)
During that same 9th Century BCE, the Hindu philosopher Yajnavalkya said that the earth rotates around the sun, and not the reverse. The Greek Aristarchos declared as much in the 3rd Century BCE. However, this notion wasn’t generally accepted until after the invention of the telescope 400 years ago—and even then the Church fought back, imprisoning Galileo for daring to say that the earth is not the center of the universe. Yet to this day vast swaths of the population of the First World haven’t gotten the memo. According to a National Science Foundation survey, 34% of Europeans and 26% of Americans still believe that the sun revolves around the earth. Now, of course, with a new administration dedicated to destroying public education, denying science, and creating a fact-free political climate, we can expect those percentages to increase.
The brightest among us continue to push back the clouds of ignorance. Who knows what the telescopes and space probes will find? What theories will be developed to explain dark matter, dark energy, or the origins of the universe in the next 400 years? Assuming our species survives that long. To conclude with a quote from Dr. Rubin:
“In a spiral galaxy, the ratio of dark-to-light matter is about a factor of 10. That’s probably a good number for the ratio of our ignorance to knowledge. We’re out of kindergarten, but only in about third grade.”