We cannot measure the slowing of time near the Big Bang because there is no “cosmic clock” outside of this event against which to compare. | Published: May 11, 2026 Shortly after the Big Bang, the universe was made up of dense plasma, as imagined here, with the particles within it moving at nearly the speed of light. Credit: Andrii, Generated with AI/ADOBE STOCK Since the universe was very small right after the Big Bang and yet it contained the same amount of matter as now, would the intense gravity have slowed the passage of time? Roger Reed Pierre, South Dakota Shortly after the Big Bang, the density of the universe was greater than the inside of a neutron star … greater than the density of nuclear matter … greater than everywhere in space.  We know that neutron stars are so dense — they squeeze roughly twice the mass of the Sun into an object only the size of a small city — that their mass starts to warp local space-time around them severely.…