Your Feet Are Aging Slower than Your Head - with Vlatko Vedral #shorts #science #gravity #physics

Royal Institution
Royal InstitutionApr 9, 2026

Why It Matters

Even a centimeter‑scale gravitational time shift matters for GPS accuracy and validates Einstein’s theory, driving advances in precision timing.

Key Takeaways

  • Feet experience slightly slower time than head due to gravity
  • Difference is about 10⁻¹⁶ seconds per second of life
  • Over a lifetime, total offset remains undetectable biologically
  • Atomic clocks can measure gravitational time dilation over centimeters
  • Interstellar depicted extreme dilation near neutron star, illustrating concept

Summary

The short video explains that because of Earth's gravity, clocks lower in the gravitational potential—like the feet—run infinitesimally slower than those higher up, such as the head.

The effect is minuscule: a foot‑head differential amounts to roughly 10⁻¹⁶ seconds per second, which over an 80‑year lifespan adds up to less than a microsecond and is biologically irrelevant. Modern optical atomic clocks, however, are precise enough to detect the shift caused by moving a clock just a few centimeters in altitude.

The presenter cites the film *Interstellar*, where a spacecraft near a neutron star experiences dramatic time dilation, and notes that raising an atomic clock by 10 cm already alters the last two or three digits of its readout.

While the phenomenon has no practical health impact, it underpins technologies like GPS and offers a laboratory‑scale verification of general relativity, reinforcing the need for ever‑more accurate timekeeping in navigation and communications.

Original Description

Your feet are younger than your head (by fractions of a second) ⏱️
Vlatko Vedral explains how gravity slows time, ever so slightly, closer to Earth’s centre. With today’s atomic clocks, even a few centimetres in height reveals the effect.
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