Cosmos: A Spacetime Odyssey, Episode 5, “Hiding in the Light”
With computer graphics getting cheaper and better every year, every new TV show and movie has to grapple with the question of how much is too much. That’s no less true for a hard-science series like Cosmos than it is for a sci-fi drama. There’s always the temptation to put more flashy visuals on screen just because you can, and the technology we have now makes it possible to show razzle-dazzle that would have been inconceivable in Carl Sagan’s original series.
But while the wow factor can be crucial to attracting an audience, the question of whether it advances the science is more complex. When done well, it makes it easier for viewers to visualize a difficult concept. But it’s not always necessary, and I think this episode proved that. It had noticeably less in the way of special effects than previous episodes – no showy black-hole spelunking, no Halls of Extinction – and told most of its major stories through animation. Yet it wasn’t any weaker for it. In fact, this was an outstanding episode, tightly written and well-focused.
First up, it was about time that Cosmos acknowledged some non-Westerners, and this episode delivers. On a theme of ancient experiments with light, we’re introduced to the Chinese philosopher Mozi, who taught an advanced utilitarian ethics and was apparently the first person to write down the principles of the camera obscura (but whose teachings were brutally suppressed by the emperor Qin Shi Huang, from whom the word “China” derives). We also meet the Arab philosopher Ibn al-Haytham, or Alhazen, who pondered the nature of light and vision during Islam’s golden age – which, as Neil deGrasse Tyson rightfully points out, was when Muslims kept the light of science and philosophy alive while Europe was sunk in the Dark Ages.
Even if inadvertent, this was a potent rejoinder to those who assert that science was or could only have been a Christian invention. It showed that the scientific revolution in Europe was built on a foundation of ideas that came from outside the continent, and more importantly, that the seeds of scientific thought – fearless questioning of received wisdom, intellectual openness, curiosity about nature – have existed in many cultures. They’re in no way a uniquely European invention.
Next, we revisit some of the famous names we’ve already met in previous episodes: how Isaac Newton discovered the spectrum of colors by passing light through a prism; or how William Herschel asked what seemed like a common-sense question – do the different colors of light have different temperatures? – and serendipitously discovered infrared radiation while trying to find out. (As I said on Twitter, the difference between us and great scientists may just be that they think to ask questions like this.)
Fraunhofer’s great discovery was the observation of absorption lines in the spectrum of the Sun. By building on his discovery, we learned that each element absorbs a different set of wavelengths, producing a characteristic “fingerprint” of dark bands in the spectrum. This work launched the modern field of astrophysics; it was the key to proving that everything in the cosmos, from the Sun to the planets to distant galaxies, is all made of the same basic elements that we find on Earth. (One of my favorite astrophysics facts is that absorption spectra were used to discover helium in the Sun before it was known on Earth). It even provided crucial support for the theory of the Big Bang: the absorption lines in light from distant galaxies are all shifted toward the red end of the spectrum, showing that these galaxies are racing away from us as space expands and carries them along.
The episode wrapped up with a lovely sequence that showed a city skyline and the night sky beyond in different wavelengths of light – infrared, radio, X-rays, gamma rays – to demonstrate how each kind of light reveals something different about our universe. The background music, which jumped around in pitch as we switched views from one wavelength to the next, was a clever, subtle touch. The pacing did feel a little rushed right at the end, although there wasn’t anything that could obviously have been trimmed. This, again, is a case where I think we should blame the relentless push of commercial demands, not the writers of the show doing their best with the time they have.
Other posts in this series: