Clara Sousa-Silva: Searching for Signs of Life on Venus and Other Planets | Lex Fridman Podcast #195

The following is a conversation with Clara Sousa-Silva, a quantum astrochemist at Harvard specializing in spectroscopy of gases that serve as possible signs of life on other planets, most especially, the gas phosphine. She was a co-author of the paper that in 2020 found that there is phosphine in the atmosphere of Venus, and thus, possible extraterrestrial life that lives in its atmosphere. The detection of phosphine was challenged, reaffirmed, and is now still under active research. Quick mention of our sponsors: Onit, Grammarly, Blinkist, and Indeed. Check them out in the description to support this podcast. As a side note, let me say that I think the search for life on other planets is one of the most important endeavors in science. If we find extraterrestrial life and study it, we may find insights into the mechanisms that originated life here on Earth, and more than life, the mechanisms that originated intelligence and consciousness. If we understand these mechanisms, we can build them. But more than this, the discovery of life on other planets means that our galaxy and our universe is teeming with life. This is humbling and terrifying, but it is also exciting. We humans are natural explorers. For most our history, we explored the surface of the Earth and the contents of our minds. But now with space-faring vessels, we have a chance to explore life beyond Earth, their physics, their biology, and perhaps the contents of their minds. This is the Lex Fridman Podcast, and here is my conversation with Clara Sousa-Silva. Since you're the world expert in, uh, well, in many things, but one of them is phosphine, would it technically be correct to call you the queen of phosphine?

I go for Dr. Phosphine. Queen is an inherited title, I feel.

Yeah. But you still, uh, rule by, um, love and power, so ... But while, while having the doctor title.

Yeah.

I got it.

Kindness.

Kindness, kindness. In September 2020, you co-authored a paper announcing possible presence of phosphine in the atmosphere of Venus, and, uh, that it may be a signature of extraterrestrial life.

Big maybe.

Big maybe. There was some pushback, of course, from the scientific community that followed, friendly, loving pushback.

(laughs)

Um, then in January, another paper from, uh, University of Wisconsin, I believe, confirmed the finding. So where do we stand in this saga, in this mystery of what the heck is going on, uh, on Venus in terms of phosphine and in terms of aliens?

Okay, let's try to break it down.

Okay.

The short answer is we don't know. Um, I think you and the rest of the public are now witnessing a pretty exciting discovery, but as it evolves, as it unfolds, um, we did not wait until we had, you know, years of data from 10 different instruments across several layers of the atmosphere. We waited until we had two telescopes, uh, with independent data months apart. But still, the data is weak. It's noisy, it's delicate, it's very much at the edge of instrument sensibility, sensitivity. And so we still don't even know if it is phosphine. We don't even really know if the signal is real. People still disagree about that. And I think it ... At the most, more philosophical end of how this happened, I think it is a distinction, and myself and other co-authors were talking about this, it's a distinction between hypotheses generation and hypotheses testing.