StarTalk Radio: Are We Alone? with Jill Tarter

Host: Neil deGrasse Tyson
Guest: Jill Tarter (Co-founder, SETI Institute)
Co-host: Matt Kirshen
Date: August 19, 2025

Overview

In this Cosmic Queries edition of StarTalk, Neil deGrasse Tyson and comedian Matt Kirshen welcome Dr. Jill Tarter—pioneer in the Search for Extraterrestrial Intelligence (SETI) and inspiration for Carl Sagan’s Contact. The discussion covers humanity's centuries-long quest to discover life beyond Earth, the technical and philosophical challenges of detecting alien intelligence, and listener questions about ethics, technology, and the daunting odds of making contact.

Main Discussion Points & Insights

1. Jill Tarter’s Background & Early Work

• Brown Dwarfs Discovery:
  • Jill Tarter recounts her doctoral thesis on "brown dwarfs"—objects more massive than planets but too small to sustain hydrogen fusion like regular stars.
    • “My thesis was about what I call brown dwarfs. Stars that are too low mass to stably fuse hydrogen at their cores.” (03:26, Jill Tarter)
• SETI Involvement:
  • By chance, Tarter was recruited to early SETI efforts because of her computer programming skills, despite the infancy of digital technology.
    • “I learned how to program the first computer that we ever had on our desktop…you had to program each step in octal. Right. So you had to set all the ones and zeros by hand.” (05:45, Jill Tarter)

2. SETI’s Focus on Technological Intelligence

• Search for Techno-signatures:
  • SETI is primarily searching for evidence of advanced civilizations—in particular, those that leave detectable technological traces (e.g., radio signals), not just biology.
  • “We're looking for something, someone that can modify its environment in ways that we could sense over the vast distances between the stars.” (10:21, Jill Tarter)
• Limits of SETI’s Technology:
  • The search is naturally limited by the capabilities of current equipment; intelligent civilizations lacking radio or powerful tech would be invisible to us.
  • “If you found an Earth that had a Roman Empire…you would pass them by saying, nothing here. Keep walking.” (11:23, Neil deGrasse Tyson)

3. Why Radio Waves?

• Physics of Interstellar Communication:
  • Radio waves pass through cosmic dust, unlike visible or infrared light, making them optimal for communication across the galaxy.
    • “Radio...they basically don't see the particles, they don't see the dust, and are not absorbed by it…We’ve been looking at the center of the galaxy at radio waves from very early times in this scientific discipline.” (16:11, Jill Tarter)
• SETI’s Assumptions:
  • The search presumes alien civilizations would discover and use similar physics, at least at some point in their development.
    • “Any aliens would have to know enough astrophysics to conclude that radio waves would penetrate space in the way other bandwidths wouldn't.” (17:14, Neil deGrasse Tyson)

4. How Much Have We Searched?

• The ‘Glass in the Ocean’ Analogy:
  • Jill Tarter addresses the scale of humanity’s search for alien signals, using her famous analogy:
    • “All the searching we'd done to date was as if we said, ‘oh, we're going to look for fish in the ocean’ and what we did was take an 18 ounce glass and dip it in the ocean and take a look and say, ‘are there fish in there?’…You have to look harder. That's where we are.” (18:59, Jill Tarter)

5. The Significance of Contact

• Existential Meaning:
  • The discovery of another technological civilization would imply hope: advanced societies can survive their own adolescence.
    • “If you were to succeed, you would by inference, know that it's possible to outlive your technological infancy and to have a long future.” (20:02, Jill Tarter)

Memorable Quotes & Notable Moments

• On the Intersection of Bias & Technology:
  • “You can't search for intelligent life that does not have technology.” (11:23, Neil deGrasse Tyson)
• On the Challenges of SETI:
  • “Might have. But on the other hand, if you're stubborn, you might have turned that around and said, wow, this is one of the most interesting questions that humans can ask about themselves and their place in the cosmos.” (20:02, Jill Tarter)
• On Disclosure:
  • “I'm going to tell the world about what we found and at least my interpretation of what that means. But the world is going to decide how they're going to react.” (22:52, Jill Tarter)

Key Listener Questions & Timestamps

• What happens if we find alien life? (22:39)
  • Tarter emphasizes transparency but says humanity’s reaction is unpredictable.
• Arthur C. Clarke’s “Equally Terrifying” Quote (23:30)
  • Tarter finds both possibilities “extremely significant,” noting that finding others offers hope, while our solitude is daunting.
    • “Both are extremely significant. One is not so hopeful in terms of the continued existence of life on Earth. The other is…incredibly exciting and impactful to know.” (24:19, Jill Tarter)
• What does SETI actually ‘listen’ for? (25:13)
  • SETI looks for narrowband signals that nature cannot easily replicate, indicating artificial origin.
    • “What we use instruments to try and detect is the kind of emissions that nature can't do…narrow band transmissions.” (26:25, Jill Tarter)
• Could aliens detect our TV/radio signals? (30:03)
  • Likely only the carrier signal, not the actual content, is detectable from afar. (30:54, Jill Tarter)
• Should we send signals or build structures to get noticed? (34:20; 35:47)
  • Passive listening is far cheaper and less disruptive than actively transmitting; funding and practicality prevent large-scale active efforts.
    • "If everybody's listening and nobody's talking, we're not going to succeed." (36:46, Jill Tarter)

Ethics, Funding, & Future Speculations

• Ethical Guidelines for Contact (38:11, 40:22):
  • SETI follows international principles for data verification/announcement, but further ethical decisions would likely be shaped by religion and geopolitics, especially in the case of intelligent (not microbial) life.
    • “The ethics are going to come from probably the religious entities across the planet, and those are different and they have different perspectives.” (40:22, Jill Tarter)
• International Competition:
  • The Chinese have the world’s largest radio telescope; first contact might not be an American discovery. (43:17)
• Technological Limitations & Future Physics (45:30):
  • While SETI searches for radio signals, Tarter acknowledges we may be limited by our own physics—not ruling out the possibility of undiscovered means of communication.
    • “We think about it, but we don't know how to do it right.” (46:34, Jill Tarter)

Probability, The Drake Equation, and The Odds

• Co-temporality Problem (48:01):
  • SETI’s odds of detection depend on both the lifetime of technological civilizations (L in the Drake Equation) and the overlap of their communicative phases with our own.
    • “Unless L…is large, there's not going to be any success. There won't be any overlap.” (48:21, Jill Tarter)
• Drake Equation (49:33):
  • Describes the variables involved in estimating the number of detectable civilizations.
    • “The number of technological civilizations in the Milky Way galaxy…can be estimated by taking the rate of star formation…multiplying that…by the average longevity of the technologies…” (49:33, Jill Tarter)
• Current Best Guess:
  • Civilization length (L) is at least about a century (our own radio era), but the upper limit is unknown.

On UFOs and Recent Congressional Hearings

• SETI’s Involvement in UFO Discourse (51:59):
  • Tarter maintains that thorough, ordinary explanations exist for most reported phenomena.
    • “If you can explain the evidence with ordinary means and ordinary physics…then, you know, go home. Occam’s razor.” (53:02–53:37)

Fun, Tone, and Pop Culture References

• The Inspiration for Contact’s Ellie Arroway:
  • Sagan's protagonist was based on Tarter: “Carl was a member of our board of directors. He wrote a book about a woman who does what I do.” (13:29, Jill Tarter)
• Humorous Banter:
  • Discussing whether comedians would expect aliens to have their own comedians or if we’d be the “vegetables” in alien culinary culture. (40:00, 55:57)
• Running Joke:
  • Neil offers to push for a ‘volunteer tax’ on alien movies to fund SETI. (54:29)

Final Thoughts

• Persistence & Hope:
  • Despite daunting odds and slow progress, the search itself is among humanity’s most profound scientific quests. The hope is, as Tarter summarizes, “When we succeed, we'll know we've done the right thing.” (29:55)
• Promise of Transparency:
  • Jill Tarter assures: “When we make contact, you will know. I'm going to tell the world.” (22:52, 55:06)

[End of summary]