Answer:
It is such a colossal amount that it defies the imagination.
An international team of astronomers managed to measure the light emitted by stars that exist or have existed.
The universe is estimated to be 13.8 billion years old. The scientists responsible for the study assure that their calculation reaches stars born when the universe was barely a billion years old.
"This calculation had never been done before," said Marco Ajello, an astrophysicist at Clemson University in South Carolina, United States, and one of the authors of the study published in the journal Science.
The light emitted by all these stars is equivalent, according to the study, to 4x10 ^84 photons or particles of light.