Why is space so dark even though the universe is filled with stars?

[Admin]

Astronomers estimate that there are about 200 billion trillion stars in the observable universe. And many of those stars are as bright or even brighter than our sun. So, why isn’t space filled with dazzling light?

Why is space so dark even though the universe is filled with stars? : Read more

 

[rod]

"People have been asking why space is dark despite being filled with stars for so long that this question has a special name — Olbers' paradox."

My notes. Could axion decay underlie excess cosmic optical background?, https://phys.org/news/2022-12-axion-decay-underlie-excess-cosmic.html

ref - New Horizons Observations of the Cosmic Optical Background, https://iopscience.iop.org/article/10.3847/1538-4357/abc881, 11-January-2021. "Abstract We used existing data from the New Horizons Long-range Reconnaissance Imager (LORRI) to measure the optical-band (0.4 ≲ λ ≲ 0.9 μm) sky brightness within seven high–Galactic latitude fields..."

My observation. To calculate excess cosmic optical background, various sources that emit optical light must be calculated too and how much optical light they would release, including factoring redshift too. From the reference paper link, "1. How Dark Does the Sky Get? The simple fact that it is dark at night, known as "Olber's paradox", argues that the universe is finite in time or space (Harrison 1987)..."

My observation. How dark the night sky is points to a finite size universe with a finite age, thus a distinct beginning.

 

[rod]

My note, the space.com article states, "we live in a very special time in the universe’s life". Yes indeed, otherwise we would not see the Universe astronomers do today. Consider cosmology, the beginning features inflation and the inflaton or origin of the solar system in astronomy. A lot of violent catastrophism operating during the beginning of our solar system, for example giant impact with Theia for the origin of the Moon. We would not be here today *living in those times*, so we live in a *very special time* to see nature today.

 

[Pogo]

if there were infinite stars and no gas and dust, and no Redshift, the sky would be infinitely bright; solid bodies would probably not form due to the high heat.
But, there are not an infinite number of stars within the distance of zero or small redshift. Beyond the distance of significant redshift, the light emissions of stars have shifted below the visible spectrum.

 

[EmmBee]

This is the old 'Olbers Paradox', and we now know Space is filled with dust and yet undefined mass apparent. Dedicated research is ongoing and theories are several. You may do your own R & D for the fun of discovery !
You're welcome...

 

[Pogo]

This paradox was referred to in an old astronomy text from 1948 I had when I was a kid. It stated exactly that, infinite stars would necessarily result in infinite light, therefore the sky is finite. It didn’t need to take into account dust and gas, and Redshifting.

 

[Questioner]

If the furthest stars/galaxies from us are traveling at near luminal speed wouldn't even further (unseen) stuff be traveling at superluminal speed, making the luminal speed limit a local phenomenon?

 

[Classical Motion]

"Why is space so dark even though the universe is filled with stars?"

1. Space is larger than you can imagine.

2. All electric fields are self repulsive. This causes light to diverge. It spreads, loses density and loses intensity. It dissolves into space. Light has limited range. Limited range on it's own, no expanding space needed.


And that's why it looks dark. Actually it's quite bright........because it's a multi-exposure. If we could only see the present universe......it would probably be quite dark. And extremely lonely.