Primordial helium measured at 24.58% of early universe mass

The LBT Y P project measured primordial helium in 54 metal-poor galaxies, finding it makes up 24.58% of the universe's initial matter by mass. The result matches the Planck cosmic microwave background estimate of 24.67%, reinforcing a key pillar of the Big Bang model.

• Primordial helium accounts for 24.58% of early universe mass
• Planck CMB estimate of 24.67% agrees with the new measurement
• About 90% of cosmic helium is primordial, 10% came from stars
• Study sampled interstellar gas regions in 54 galaxies