With the motion of life, cause and effect feel certain. We see stable patterns. But Hume reminds you, correlation does not guarantee causation.
Subject: Causation versus Correlation.
Reasoning asks you to question whether you’re seeing real causation, or just a misleading correlation. Always ask: What’s the evidence? Hume said, repeated observation shows habit, not logical necessity. If a cause exists, find it!
We are not separate from the universe—we are expressions of it, linked by matter, chemistry, and atoms.
Subject: We Are Stardust.
Carl Sagan reminds us that we are intimately connected to the universe. The particles that form our bodies are borrowed from a cosmic pool of just 17 particles and four forces. Even more humbling, the molecules within us were forged in the hearts of stars, linking us directly to the vast cosmos that surrounds us.
In 1842, Christian Doppler wrote about the doppler effect in stars. It was first confirmed with sound in 1845, then with light in 1848. The big moment came in 1868 when, for the first time, we could tell which stars were coming and going.
Subject: Waves.
When a source moves toward you, waves compress and frequency increases; when it moves away, waves stretch and frequency decreases. This applies to sound (changing pitch), and light (changing color, or redshift).
Water doesn’t weaken a permanent magnet, but time eventually does.
Subject: Magnets.
Water does nothing to magnets, not even temporary ones. And permanent magnets are only “permanent” on a human scale. Over time, the forces and interactions of the universe slowly change the alignment of their magnetic domains. Most permanent magnets last for decades or centuries unless you heat them, strike them, or expose them to a strong opposing magnetic field. In deep space, some might hold their magnetism for billions of year
Change is the only form of permanence that exists—first glimpsed by ancient thinkers, and now woven into the fabric of modern science.
Subject: Impermanence.
Heraclitus’ claim that “everything is in flux” captures a deep truth shared by both metaphysics and classical physics. The world appears stable only because change often happens gradually. Beneath every solid object, fixed identity, and steady law lies continuous motion, transformation, and becoming. What endures is not stillness, but patterned change.
In 1842, the Doppler effect was proposed by Christian Doppler. First confirmed for sound in 1845, then for light in 1848.
Subject: Light Waves.
In 1848, the Doppler effect was extended from sound to light when astronomers noticed that starlight shifts in frequency, revealing stellar motion through subtle changes in color. This is the first time we knew which stars were coming and going.
Analog is the wave. Digital describes the wave. Analog mirrors the continuous shape, digital samples the shape. Most people do not hear a difference.
Subject: Electromagnetic Force.
Analog and digital reveal a deeper truth about description. Analog mirrors the continuous shape of the wave. Digital samples that shape, leaves out some in-between detail, and rebuilds what matters. Most people cannot hear the difference, but some audiophiles say they can. Sometimes “incomplete” is still complete enough.