Lost Starlight

[Zinjanthropos]

Just wanted to know if someone has figured out how much starlight has been lost since the first light emitting star in the universe. Appears as if someone did. They also have a number for amount of photons that have been emitted since then.

https://www.smithsonianmag.com/smart-new...180970938/

Excerpt:

The team looked specifically at data from the extragalactic background light (EBL) a cosmic fog permeating the universe where 90 percent of the ultraviolet, infrared and visible radiation emitted from stars ends up.

What is the Cosmic Fog? Are they saying 90% of starlight has been lost over the eons?(found that a little confusing)

[C C]

[...] What is the Cosmic Fog? Are they saying 90% of starlight has been lost over the eons?(found that a little confusing)

The opposite. The EBL is just the term or generalization for what the article is about: The accrued EM radiation across the aeons that is still traveling/circulating or has not been absorbed. That's why it's metaphorically referred to as a "fog" filling space. Like the CMB, which purely dates back to circa 380,000 years after the birth of the universe and has diluted to microwave range. The EBL, OTOH, embraces most of the rest of the wavelengths emitted by stars and galactic centers over the course of 13+ billion years.

EDIT: CB and the slipperily chronicled DEBRA are arguably more inclusive labels collectively embracing CMB, EBL, etc.

[Zinjanthropos]

[...] What is the Cosmic Fog? Are they saying 90% of starlight has been lost over the eons?(found that a little confusing)

The opposite. The EBL is just the term or generalization for what the article is about: The accrued EM radiation across the aeons that is still traveling/circulating or has not been absorbed. That's why it's metaphorically referred to as a "fog" filling space. Like the CMB, which purely dates back to circa 380,000 years after the birth of the universe and has diluted to microwave range. The EBL, OTOH, embraces most of the rest of the wavelengths emitted by stars and galactic centers over the course of 13+ billion years.

EDIT: CB and the slipperily chronicled DEBRA are arguably more inclusive labels collectively embracing CMB, EBL, etc.

Would they take into account the light that couldn’t escape in the first 380,000 years or the light that doesn’t escape or is captured by the black holes permeating the universe/galaxy centres? Are their calculations based on light that is absorb by matter other than BH’s?

[C C]

Would they take into account the light that couldn’t escape in the first 380,000 years or the light that doesn’t escape or is captured by the black holes permeating the universe/galaxy centres? Are their calculations based on light that is absorb by matter other than BH’s?

I suspect it's more of a guesstimate than a literal measurement (and is obviously limited to the visible universe), but regardless, it's an assessment of what was originally emitted by stars prior to contingent absorption incidents occurring later. The earliest time "measured" would date back to when stars first formed circa 250 million years after the Big Bang. Though they place the emphasis on light emitted by stars, the EBL itself actually includes radiation from proto-stellar nurseries and non-stellar type emissions at the core of galaxies.

https://www.science.org/doi/10.1126/science.aat8123

This allowed us to reconstruct the evolution of the EBL and determine the star formation history of the Universe over 90% of cosmic time.

https://news.clemson.edu/clemson-scienti...-universe/

“By using blazars at different distances from us, we measured the total starlight at different time periods,” said Paliya of the department of physics and astronomy. “We measured the total starlight of each epoch – one billion years ago, two billion years ago, six billion years ago, etc. – all the way back to when stars were first formed. This allowed us to reconstruct the EBL and determine the star-formation history of the universe in a more effective manner than had been achieved before.”

[...] Putting a number on the amount of starlight ever produced has several variables that make it difficult to quantify in simple terms. But according to the new measurement, the number of photons (particles of visible light) that escaped into space after being emitted by stars translates to 4×10^84.