system
Given the following post, respond as if you're commenting on Reddit:
human
[The Witcher 3] What exactly is The White Frost? Is it something artificial? Magical? Or a natural process like entropy?

Haven't been able to work this one out. It seems like an unstoppable force akin to entropy where eventually all worlds lose heat and energy becoming icy and lifeless. Perhaps it's more to do with each planet's star going supernova, and the worlds losing heat from their sun? Either way, it appears that The White Frost is the result of extremely powerful magic or unchangeable laws of physics due to the notion that only someone with Elder Blood (a rather notable trait and insanely powerful in magic that tends to bend the laws of physics) can actually stop it. 

So what is it? And how exactly does someone with Elder Blood stop it?
gpt
A (presumed) magical WMD that caused an unsurvivable ice age in one dimension or "sphere", before eventually making its way to another.

As to how it's stopped, there's unfortunately no canon answer to give other than "magic".