For years, astronomers and physicists have calculated the age of our universe by measuring the time elapsed since the Big Bang and by studying the oldest stars based on the redshift of light coming ...

In physics, there are a host of standard constants: the speed of light, the charge-to-mass ratio of the proton, and Planck's constant, to name just a few. Repeated measurements going back a few ...

The kilogram — anywhere in the world, for any purpose — is based on the exact weight of a golf-ball-sized chunk of platinum and iridium stored under three glass bell jars in a vault in an ornate ...

YET another fundamental constant of nature may have changed over the last 12 billion years. If confirmed, the result could force physicists to radically rethink their theories and provide support for ...

The kilogram finally has a precise meaning despite defying a rigorous definition for over a century. Delegates of the General Conference on Weights and Measures unanimously voted Nov. 16 in favor of a ...

Through extremely high precision measurements of a pulsar orbiting a white dwarf star, astronomers have found that the gravitational constant, which dictates the force of gravity, is "reassuringly ...

Astrophysicists have performed a powerful new analysis that places the most precise limits yet on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find ...