Cosmos: A Spacetime Odyssey, Episode 11, “The Immortals”
As the new Cosmos approaches its final episode, it’s about time that the series started looking back on the ground it’s covered and drawing some larger lessons. This episode accomplished that, and while it treads into more speculative territory than earlier outings, I think that’s appropriate.
But first, there was a scene about someone I’d never heard of: Enheduanna, a Sumerian high priestess who holds the honor of being the most ancient author whose name we know. (The most ancient person whose name we know is probably the Egyptian ruler Iry-Hor, but Enheduanna is the oldest who speaks to us in her own words.) It even quoted a line from one of her poems, giving those ancient cuneiform texts new life in a medium their creator could never have imagined.
The invention of writing allowed human beings to transcend death, to transmit messages across the generations to those not yet born. This point led into the oldest story known to humanity, the Epic of Gilgamesh, which includes the figure of Utnapishtim, a legendary mariner who was ordered by the gods to build a wooden ark which carried two of every animal so that life would survive a global flood. Utnapishtim is unquestionably the source of the much later story of Noah, which Tyson emphasized, much to my glee and creationists’ likely chagrin.
There’s a connection here that I was very pleased to see made: Life transmits itself the same way as writing. The genetic code of DNA is an immortal message, which propagates through time along a chain of transient physical vessels, just as our stories are copied and reprinted by scribes and publishers. The story of life is a continuous thread spooling back to its origin, though that origin is still a mystery to us.
And it’s reasonable to wonder whether that thread is part of a larger tapestry: whether life might exist on other planets, or even whether it could spread from one planet to another by panspermia. With a sample size of one, there’s no real way to answer this question yet, although the episode did spend a fair amount of time on the possibility. It also presented an intriguing if speculative idea: that life could have survived the giant impacts that repeatedly sterilized and melted Earth early in its history by microbes hitching a ride into space on impact ejecta, falling back and germinating once the planet had cooled again.
And if life exists elsewhere, could we ever communicate with it? We’ve been listening for extraterrestrial transmissions with no success, but I was delighted to see this episode venture a speculation that I’ve made before: maybe the reason we haven’t detected alien signals is that there’s something better than radio waves which all advanced civilizations use to communicate, and which we don’t even know to look for yet.
The other, more pessimistic possibility is that we haven’t heard from aliens because, on the timescale of the universe, technologically advanced civilizations don’t last long. And it has to be said that human history offers little evidence to contradict this.
Some cultures collapse because of catastrophes that are impossible to predict, like the Toba event in Indonesia about 75,000 years ago: a supervolcano eruption which was so enormous it plunged the entire planet into a volcanic winter, and which may be the cause of a bottleneck in human population found in genetic studies. Others are destroyed in war, as was the case when European colonizers decimated the native people of the Americas; although, as Tyson notes, their genocidal victory was due less to their superior weapons and more to the diseases they carried, to which indigenous Americans had no resistance.
But many cultures contain the seeds of their own downfall. Mesopotamian civilizations like Enheduanna’s constructed ingenious irrigation systems, but climactic shifts and the slow accumulation of salt in the soil eventually doomed them. This story of a culture poisoning itself with its own waste products, of course, is an irresistible analogy to the widespread climate change we’re now causing.
The Mesopotamians didn’t realize what they were doing, but as Neil deGrasse Tyson pointed out two episodes ago and reiterated this time, we don’t have that excuse. If we had the collective will, we could avert almost any peril that might threaten us. The greatest danger we face isn’t from natural events, but from malignant ideologies that turn us against ourselves or cause us to avert our eyes from disaster barreling down. (My wife pointed out that they showed a snippet of Adolf Hitler at the same time Tyson was talking about climate-change denial, which may have been deliberate.)
Appealing to fear is one way of motivating people, by pointing out a danger and urging them to take some action to avert it. When the danger is real, this is legitimate and valid. But there’s another way to motivate people, and that’s by appealing to hope: painting a picture of what we could achieve if we overcome the challenges we face, inspiring people so that they want to make that vision reality.
To that end, the end of this episode introduced a second Cosmic Calendar, showing the next fourteen billion years and what may lie ahead. This was some of the most unbridled speculation of the series, but it was glorious: the reversal of global warming, the settlement of Mars, and humanity’s departure from the solar system as we set out to colonize other worlds. (It even showed the space arks!)
The best compliment I can give this episode is that it captured that spirit of wonder that Carl Sagan was best known for. It was a forceful reminder that in spite of the greed, ignorance and bigotry that keep us earthbound, we’re capable of wondrous things. That is and should be the most potent argument that we can make. Ever since Sumerian writers inscribed their vision on clay tablets, humanity has dreamed of reaching the stars; but it’s only by following the light of reason that we’ll ever reach them.
Other posts in this series: