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Blink 3 of 8 - The 5 AM Club
by Robin Sharma
Listen to the Intro
Crush summary
James Riordon
Close Encounters with Gravity
22 mins
Brief summary
Crush by James Riordon delves into the complex dynamics of unrequited love, offering insights on navigating intense emotions and the interplay of identity and desire, blending personal narrative with psychological exploration.
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Crush
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Key idea 1 of 5
Freefalling, and feeling gravity
What is gravity? Even if you can’t define it, we all have a strong relationship with it. There’s that queasy sense of fear you get when you’re standing at the edge of a drop. Whether it’s a rooftop, a cliff, or the lip of a snowboarding superpipe, gravity is what gets you moving at sixty kilometers an hour during a typical freefall, and that’s strong enough to make your nerves jangle and take a step back.
Acrophobia, or a fear of heights, feels like ancient wiring, a survival instinct baked into our DNA. But is it really? Psychologists in the 1950s built the famous “visual cliff” experiments. They put young animals on a glass platform that suddenly revealed what looked like a sheer drop: rats, kittens, goats, turtles, even baby goats and chicks. Most balked or froze. Human infants showed racing heartbeats and clung to caregivers when carried toward the “cliff.” For years, that was taken as proof that fear of heights was innate. But later work showed a twist: human infants are drawn to cliffs. Their hearts pound mostly from excitement. Acrophobia, like many phobias – be it snakes, spiders, or strangers – seems to be something we learn through bad experiences and warnings. That matters, because learned fears can be treated.
Now, as for the physics of gravity’s “pull”. At Earth’s surface we live under about one g of acceleration, 9.8 meters per second per second. That steady tug has a lot of influence. It’s what keeps our bones dense and our muscles engaged, along with deciding how quickly we speed up when we fall. Whenever we’re on a swing or a rollercoaster, we flirt with changes in g, but those are short, playful jolts. As for astronauts in orbit, they live in near-continuous freefall. Blood shifts from legs to chest and head, calves shrink, torsos puff slightly, and many battle nausea, headaches, and disorientation before longer-term issues like bone loss, muscle wasting, vision changes, and mood disorders set in.
Since there’s plenty of interest in preparing for a future when people might spend more time in space or lower gravity environments, efforts have been made to combat these side-effects. But so far, we’ve only found partial fixes, like bungee-tethered treadmills, resistance machines, and vacuum “pants” that pull blood toward the legs. They help but can‘t fully substitute our need for Earth-like gravity.
It’s a problem that’s led to some wild ideas. At some point in the next few billion years, the Sun’s rising heat will make the Earth uninhabitable – at least in its current position. One possible solution – one that solves some of the issues around gravity and resources – would be to turn Earth into a rogue planet. Carefully timed gravitational slingshots could, in principle, tug Earth itself outward when the Sun swells into a red giant, turning our planet into a slow-moving, fully furnished ark. That dream of “Spaceship Earth” sets up the next question: what makes any world a good home in the first place?
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What is Crush about?
Crush (2025) pulls you into a world where everyday experiences – like watching water swirl in a sink – open doors to black holes, bending spacetime, and the strange physics that shape the universe. From our fear of heights to the fate of the cosmos, it’s a fascinating look at gravity, the force we think we know best, but barely understand at all.
Who should read Crush?
- Curious science fans who love learning how the universe works
- Space enthusiasts drawn to the strange physics behind cosmic extremes
- People who enjoy big ideas about our origins
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