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The Arecibo Observatory: An inverted ziggurat?Ricardo Arduengo/AFP via Getty Images
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Space Babel

On the undignified end of the Arecibo Observatory and our search for the heavens

Adam Kirsch
December 04, 2020
Ricardo Arduengo/AFP via Getty Images
The Arecibo Observatory: An inverted ziggurat?Ricardo Arduengo/AFP via Getty Images

Reaching the heavens is one of the oldest human aspirations. No sooner had God destroyed the world in the Flood, starting the human race over with a clean slate, than they started building the Tower of Babel to touch the sky. Some scholars believe that the story in Genesis 11 was inspired by Etemenanki, a massive ziggurat that would have been familiar to Jewish exiles in Babylon. Almost 300 feet tall, it bears an inscription by Nebuchadnezzar II boasting, “I raised its top to heaven.”

The builders of the Arecibo Observatory reached quite a bit further into the heavens than that. When it commenced operation in Puerto Rico in 1963, its 1,000-foot reflector dish was the largest in the world, a title it held until 2016. In 1968, the Arecibo Observatory made the first observation of a neutron star, the Crab Pulsar, which is 7,175 light years from Earth—about 4 quintillion miles. Later, it was used for the first direct observations of a comet and an asteroid.

And now, like Etemenanki, the Arecibo Observatory lies in ruins. The telescope was made up of two separate structures: a reflector dish built into a natural sinkhole, and a receiver suspended 500 feet above by metal cables connected to three support towers. Just before 8 a.m. on Tuesday morning, the 900-ton receiver platform fell onto the dish below, destroying both.

The exact cause of the collapse isn’t yet clear—it’s been reported that the tops of the support towers broke off—but it didn’t come as a complete surprise. There have been escalating problems with the cables since August, and last month the National Science Foundation announced that it would close the observatory rather than undertake dangerous and expensive repairs. But the big crash was, in the words of one scientist quoted in The New York Times, “an undignified end” to one of the greatest structures humans have ever built.

It wasn’t God who brought down the Arecibo Observatory, the way he interfered with the Tower of Babel by “confounding the speech” of its builders, causing human languages to diverge for the first time. Nor would any of the scientists who used it describe themselves as trying to reach God, as the builders of Babel hoped to with their migdal v’rosho bashamayim, “a tower with its top in the heavens.” But the English word “the heavens,” like the Hebrew word shamayim, connotes not just the physical sky but the divine realm that has always been associated with it. For the first astronomers in ancient Greece, studying the stars was the best way to make contact with the divine. According to Plato, the reason God gave human beings the power of sight was to “behold the courses of intelligence in heaven,” to understand the divine mind through the motion of the stars.

For rationalist thinkers ever since—including Maimonides, who interpreted the Torah by the light of Greek philosophy—the miraculous is not to be found in violations of the laws of nature, but in those laws themselves. God appeared to humans only once, in smoke and fire on the top of Mount Sinai, but the movement of the stars is eternal, and anyone who studies it at any time or place can make contact with the mind of the Creator. Modern cosmologists and astronomers have the same belief: They study outer space in order to discover the laws of nature, not to find God’s hiding place or send him a message.

That’s the official view, anyway. Since space exploration began in the 1960s, however, it has also been driven by the half-admitted hope that we will find an intelligence out there. This wouldn’t be God, exactly, but it would be a nonhuman mind we can talk to and learn from, which is one of the roles God plays for us. It might even be so advanced as to appear godlike. The astronomer Carl Sagan imagined such an extraterrestrial intelligence in his novel Contact, where humanity is tutored in the secrets of the universe by aliens. (The film adaptation used Arecibo as a set.)

SETI, the search for extraterrestrial intelligence, appeals to the part of us that longs for miracles in the old, pre-rational sense—not knowledge of the laws but an exception to the laws. It draws on the same longing for absolute otherness that fuels humanity’s imagination of God. No wonder astronomers have mostly kept their distance from SETI, seeing it as rather embarrassing, more like ufology than proper science.

But not always. In fact, the most enduring legacy of the Arecibo Observatory may not be the countless observations it made, but a message it sent only once, on Nov. 16, 1974. To mark a major upgrade of the telescope, its antenna was used to beam a message at the star cluster M13, about 21,000 light years from Earth. This message, the most powerful radio transmission ever sent from our planet, is made up of 1,679 bits of data, and if properly decoded it would communicate basic facts about humanity, including the chemical composition of DNA and the average height of a human being. There is even an encoded picture of the Arecibo telescope itself.

The astronomers who created the Arecibo message, including Carl Sagan, knew that there was effectively no chance it would ever be read, much less answered. There would have to be a technologically advanced civilization in M13 looking for signals at just the right place and time, and they would have to share enough of our way of thinking to be able to decode the message. If they beamed a response back to us, someone on Earth would have to be waiting for it 42,000 years from now. When you consider that the main telescope at the Arecibo Observatory collapsed a mere 46 years after sending the message, it seems almost impossible that anything human can last long enough or reach far enough to encounter another mind. But as anyone who’s ever prayed for a miracle would tell you, almost impossible means there’s a chance.

Adam Kirsch is a poet and literary critic, whose books include The People and the Books: 18 Classics of Jewish Literature.