Scientists have found the amount of light generated Universe

Christopher Davidson
December 1, 2018

A map of the night's sky showing the location of 739 blazars used in the study to measure starlight in the universe. By peering back at the earliest days of stellar creation, scientists in SC have measured all of the starlight ever produced throughout the entire history of the observable universe.

Are you ready for the amount?

000,000,000,000,000,000,000,000,000,000,000,000,000,000 photons. Or 4×10^84.

According to the new measurement, the number of photons - particles of visible light - that escaped into space after being emitted by stars translates to 4*10.

"Thanks to the data collected by telescope "Fermi", we could measure the total amount of starlight". "The EBL represents the book reporting the story of stellar activity and galaxy evolution within the universe", Marco Ajello, lead researcher and astrophysicist at Clemson College of Science in SC, said in an email.

The new EBL measurement also provides important confirmation of previous estimates of star formation from missions that analyze many individual sources in deep galaxy surveys, like the Hubble Space Telescope. "Every single star that has existed has contributed to this emission, and we can use it to learn all the details about star formation and evolution and galaxy evolution".

To calculate all of the starlight ever produced throughout the history of the observable Universe, the team analysed nine years worth of gamma-ray output from 739 blazars - galaxies with monster black holes at their centres - and their interaction with the extragalactic background light (EBL) by NASA's Fermi Gamma-ray Space Telescope; a feat that has never been done before, said Marco Ajello, lead author of a recent research paper submitted to Science.

Astronomers believe that our Universe began forming the first stars when it was a few hundred million years old. So, in the milky way each year there are about seven new stars.

Despite the huge photon number, Earth still gets the majority of its light from the Sun due to the vast size of the universe. Now, by using an indirect method, scientists have finally made this measurement.

"Gamma rays are the highest-energy form of light".

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However, extragalactic background light is arduous to evaluate since it is expanded so thinly across the universe and is eclipsed by bright light genesis close to Earth.

"It's like following the rainbow till the end and finding the treasure. That's what we found", Ajello said.

A team of researchers analysed nearly nine years of data from gamma-ray signals stemming from 739 sources.

Gamma ray photons produced within the jets eventually collide with the cosmic fog, leaving an observable imprint.

"Gamma-ray photons traveling through a fog of starlight have a large probability of being absorbed", Ajello said.

'By measuring how many photons have been absorbed, we were able to measure how thick the fog was and also measure, as a function of time, how much light there was in the entire range of wavelengths'.

This works like a timeline of the universe.

"By using blazars at different distances from us, we measured the total starlight at different time periods", said postdoctoral fellow Vaidehi Paliya.

Scientists who study the universe want to unveil all its secrets.

'Without the evolution of stars, we wouldn't have the fundamental elements necessary for the existence of life'. But what about the very beginning of the universe? "When the right frequencies of light collide, they can convert into matter through Albert Einstein's famous equation E=mc2", said co-author Alberto Dominguez, an astrophysicist at Complutense University of Madrid. "Our measurement allows us to peek inside it".

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