with how light works and the constant expansion of what we term the “observable universe” why don’t we constantly see new stars appearing in the night sky as the observable part expands and stars/galaxies light reaches us for the first time?
The night sky has stayed relatively the same (accounting for changing postions over time, stella phenom, supernovas etc.) for all of humans written history.
In: 515
The observable universe isn’t actually expanding, it is shrinking!
Our observable universe is determined by what light has had time to reach us from distant parts of the universe. In a static universe with a specific start time this would mean that we would continually be seeing more universe as this shell expands at a rate of one light year per year. However the universe isn’t static, it is expanding in volume equally across space. As a result over larger distances this expansion increases in speed, to the point that at the very edges of our observable universe the expansion outstrips the speed of light! The amount of stars in the universe we can observe then is shrinking because space is appearing between the stars faster than light can cross it to reach us.
Edit: The other big issue with your question is that what we can observe in the sky with the naked eye is almost entirely within our own galaxy. We can see some nearby galaxies and star clusters as faint smudges, but overall the vast amount of the observable universe isn’t something that would impact our view of the night sky regardless of if it was expanding or shrinking.
Latest Answers