Astronomers have observed that the universe is expanding at an accelerated rate, a conclusion based on the redshift of celestial bodies. According to the redshift, celestial bodies move more slowly in the distant past than they do today, which means that there is something accelerating them. Astronomers use type Ia supernovae as a standard gauge for measuring large-scale lengths, using their brightness to measure distance, even if the supernova’s brightness is not the same, but their brightness changes follow a standardized curve.
Astronomers speculate that dark energy is driving the universe’s accelerated expansion. But according to a study in the journal Astrophysical Journal, a team of astronomers at Yonsei University in South Korea, the University of Lyon and the Korea Institute of Astronomy and Space Science found that the key assumption that brightness changes follow a standardized curve is likely to be wrong. The age of the supernova predecessor star was not taken into account.
This means that distance is not measured correctly and the celestial body may be closer than we thought. The universe may not have accelerated expansion.