I'm not sure anyone has really provided a complete explanation of what is the difference between working with an absolute infinity and the way we do math normally in science and such.
Basically, no one has found the idea of using an absolute infinity to explain the world to be better than the way we deal with infinity in college courses. In college, you run across the idea that some infinite sets are larger than others (countable numbers vs uncountable). Edit - I think you could have the idea of different sized infinities and a final largest absolute infinity. Itโs just that this concept isnโt useful. It would be like claiming God is purple. Nobody can prove you wrong and it doesnโt matter.
Of course, an infinite set makes sense in math, and has practical uses in the sciences, but nothing can truly be demonstrated to be unending. Another poster put it nicely - infinity is a direction, not a destination.
I recommend this video How to count past infinity by Vsauce (about 20 minutes long). It is closer to entertainment than a lecture but its pretty good. I'm only an undergrad math major but I haven't found any real problems with this video (though, he does start talking about ordinal numbers which aren't terribly useful to anyone that I know of, yet, except for some really complicated number theory stuff cryptographers might use, don't ask me. cryptographers are basically wizards imho).
The question doesn't make sense, there are many things which have an infinite quality (like infinite cardinality) or are called infinite/infinity (like infinite cardinals and ordinals). They're not contradictory. They coexist the same as all finite things do.
"Countably infinite" means an infinitely-large set of numbers that could be generated by infinitely following an algorithm with a finite number of steps. For example, natural (positive whole) numbers are countably infinite because they could be generated by following this simple algorithm:
Start with the number 1
Add 1 to your number
Repeat step 2
The set of real numbers, on the other hand, is uncountably infinite because you can have an infinite number of digits after the decimal place. You can't define a finite generation algorithm like the one above simply because any precision you use wouldn't cover the full range. In other words, if you wanted to modify the above algorithm, and chose 0.1 as your starting number, your algorithm would miss 0.01. If you chose to start at 0.01, you would miss 0.001, and so on
That is the way it is often taught but actually both sets are infinite that is have no ends or in other words are not bounded.
The thing that is confusing to understand is that the question how many there are and how much there is diverges at infinity.
Our intuition (as finite beings) is broken here. Both sets are infinite but in one is more than in the other. That does not make one set more infinite than the other. You cannot be more unending than to literally have no end.