> ... that leads to people believing there is nothing outside the observable universe
No mainstream scientific source says this. The observable universe is purely a limit on the distance we can see - a horizon - due to the speed of light and the age of the universe.
> The main evidence used as "proof" of the big bang is the observed data seeming to show that the everything in the universe is "dispersing" slowly. That is at least what I've heard claimed.
> If you proscribe to believing in the big bang, then the entirety of everything we see is an expansion from a single dense explosion of matter.
This is misleading. The Big Bang is not an "explosion" of the kind we see on Earth, where some matter is pushed apart from a central point by an explosive force. If that were the case, then what we observe would be different.
Instead, what we observe has so far only been well explained by the idea that space itself is expanding. In this model, there is no center - there's no location you can point to as where the explosion happened, the expansion happened everywhere equally, it didn't radiate outward from a central point.
We have evidence of this omnidirectional expansion, in the form of the cosmic microwave background (CMB) radiation, which is radiation from the early universe that comes from all directions in the sky, because the Big Bang similarly occurred in all directions. Again, this is not what we would observe if it was similar to a traditional explosion.
> I believe that they are seeing something similar enough that it could be perhaps a "localized bang" or something like that.
If you're thinking of something more like a traditional explosion, no, that is ruled out by the observational evidence.
No mainstream scientific source says this. The observable universe is purely a limit on the distance we can see - a horizon - due to the speed of light and the age of the universe.
> The main evidence used as "proof" of the big bang is the observed data seeming to show that the everything in the universe is "dispersing" slowly. That is at least what I've heard claimed.
There is much, much more evidence than this. Wikipedia lists observational evidence in 7 categories: https://en.wikipedia.org/wiki/Big_Bang#Observational_evidenc...
> If you proscribe to believing in the big bang, then the entirety of everything we see is an expansion from a single dense explosion of matter.
This is misleading. The Big Bang is not an "explosion" of the kind we see on Earth, where some matter is pushed apart from a central point by an explosive force. If that were the case, then what we observe would be different.
Instead, what we observe has so far only been well explained by the idea that space itself is expanding. In this model, there is no center - there's no location you can point to as where the explosion happened, the expansion happened everywhere equally, it didn't radiate outward from a central point.
We have evidence of this omnidirectional expansion, in the form of the cosmic microwave background (CMB) radiation, which is radiation from the early universe that comes from all directions in the sky, because the Big Bang similarly occurred in all directions. Again, this is not what we would observe if it was similar to a traditional explosion.
> I believe that they are seeing something similar enough that it could be perhaps a "localized bang" or something like that.
If you're thinking of something more like a traditional explosion, no, that is ruled out by the observational evidence.