Key to the Mystery of Dark Energy: Corrected Relationship between Luminosity Distance and Redshift

A new possible explanation to the luminosity distance (DL) and redshift (Z) measurements of type Ia supernovae (SNeIa) is developed. Instead of modifying the theory of general relativity or the Friedmann equation of cosmology with an extra scalar field or unknown energy component (e.g., dark energy), we re-examine the relationship between the luminosity distance and the cosmological redshift (DL Z). It is found that the DL Z relation previously applied to connect the cosmological model with the measured SNeIa data is only valid for nearby objects with Z ≪ 1. The luminosity distances of all distant SNela with Z ≳ 1 had been underestimated. The newly derived DL Z relation has an extra factor p 1 + Z, with which the cosmological model exactly explains all the SNeIa measurements without dark energy. This result indicates that our universe has not accelerated and does not need dark energy at all.