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.
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If we had a perfect resolution of the light -in all wavelengths-coming towards us, then that is what we would see.
The cosmic background radiation is visible in every direction, because that’s literally the remnants of the Big Bang. This means we’re enveloped in an ever-expanding bubble of this cosmic background radiation. This is the extreme of what we can detect.
After the big bang, there was some time that passed until the universe cooled enough to be see-through, and after even more time the first stars began to give off light.
These stars are technically the oldest things we could theoretically detect, but the light from them has travelled for billions of years, weakening it immensely, and space has expanded in that timeframe making it shift to the lower-energy end of the spectrum.
The light also must get to us without anything passing in between that can obstruct it.
So you have a very weak signal, at very low energy levels with a high chance of being obstructed.
In spite of that, with the new James Webb space telescope we can see very far because the sensors are better than ever before. However they have limits of resolution and limits in what parts of the light-spectrum we can detect.
So why can’t we see everything? Because of objects that block the light, and hardware limits of the sensors.
If we didn’t have those problems, we would indeed see everything.
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