Home Diary of a CEO Notes
Diary of a CEO · 2025-10-13 · 2h 05m

Neil deGrasse Tyson: The Harsh Truth About Horoscopes (sorry but it’s true)

Neil deGrasse Tyson dismantles astrology and offers a cosmic perspective on death, meaning, religion, AI, aliens, and why we won't reach Mars.

Neil deGrasse Tyson: The Harsh Truth About Horoscopes (sorry but it’s true)
The guest

Neil deGrasse Tyson — One of the most recognizable astrophysicists in the world, director of the Hayden Planetarium and host of Cosmos. He popularizes science and turns the mysteries of the universe into accessible life lessons.

The gist

Steven Bartlett and Neil deGrasse Tyson range across mortality, meaning, and the 'cosmic perspective' that humans are literally made of stardust and share DNA with all life. Tyson argues meaning is created rather than found, explains why he isn't afraid of death, and critiques the human tendency to divide into tribes over religion and ideology. He makes contrarian cases that humans will never reach Mars without a geopolitical driver, that the simulation hypothesis has a clever escape hatch, and that astrology and 'crystal energy' don't survive scientific scrutiny. The conversation closes on AI, the certainty of microbial alien life, and the value of basic science to civilization.

Big reveals

  • Tyson flatly says Bartlett's probability of reaching another planet in his lifetime is 'zero'.
  • Argues the Apollo program was canceled because the US only spends big when there's a geopolitical/defense reason, not for exploration's sake.
  • Lays out his simulation-theory 'escape hatch' that puts the odds we're in a base reality back to roughly 50/50.
  • Says he and two colleagues calculated about 100 living civilizations currently exist in our galaxy.
  • Admits his biggest life regret: a harsh, deflating evaluation he wrote of a young student decades ago.
  • Reveals he let go of his religious belief at age 18 and urges Bartlett not to lose his faith because of him.
  • Calls 'crystal energy' meaningless, noting crystals are literally the lowest energy state of their atoms.

Things worth remembering

  • Humans share roughly 20% of their genes with a banana, and have more in common with fungi than fungi do with green plants.
  • A single breath contains more air molecules than there are breaths in Earth's entire atmosphere, so every breath shares molecules others have inhaled.
  • Each human body radiates about 80 watts, like an 80-watt bulb.
  • Earth's escape velocity is 7 miles per second.
  • Life expectancy currently rises about one month per year; 'longevity escape velocity' is when each year adds a year of life.
  • A black hole is defined as a region where escape velocity exceeds the speed of light, so not even light can escape.
  • If the sun shut off, Earth would eventually cool to about -462°F, the background temperature of the universe.
  • Life appeared on Earth within ~200 million years of the planet cooling, suggesting life arises readily.
  • Astronomers have searched only a 'coin-sized' volume of the galaxy for exoplanets and life.
  • Tyson notes The Matrix has one physics error: using humans as an energy source violates thermodynamics, but it's needed for the plot.

Recommended in this episode

Books, products and media the guest or host genuinely endorsed here — with the buy link.

Affiliate link — we may earn a commission at no extra cost to you.

Guest’s ownBook

Just Visiting This Planet

Neil deGrasse Tyson

“It's called just visiting this planet. So, so I'd lied before. I can give you some advice.” — Neil deGrasse Tyson 02:02:56
Find it on Amazon
Guest’s ownBook

Cosmic Perspectives on Civilization (Starry Messenger)

Neil deGrasse Tyson

“I wrote a whole book, one of those books in your stash there, that one. Cosmic perspectives on civilization.” — Neil deGrasse Tyson 00:13:35
Find it on Amazon
RecommendedMedia

Cosmos

Neil deGrasse Tyson (inferred)

“I've watched Cosmos. I've watched it several times. It's one of my favorite things to watch... I try and persuade everybody to watch that.” — Steven Bartlett 00:20:21
Find it on Amazon
RecommendedMedia

The Matrix

The Wachowskis (inferred)

“Well, sci-fi is The Matrix. Why? I love everything about it. The story is tight.” — Neil deGrasse Tyson 01:25:22
Find it on Amazon