What are your opinions do do think both alicorns are immortal and can't be destory or just long lived and can die

I like to think that they are partly immortal, that they won't naturally die and are very hard to kill. But there are ways to kill them through special means.

4890093
I’d like they’re long lived. In my head cannon, the princesses, or any alicorn for that matter, age once every fifty years. So, in my head, I’d like to think the princesses are physically in their early 40s, and during Luna’s banishment, they were in they’re late teens, around 18 or 19 years old.

4890093
In my stories, Celestia, Luna and Discord all originate from the same source, they are immortal as long as they remain within Equestria, but outside Equestria they can be destroyed if they are cut off from the energies that sustain them.

6866506
That's pretty cool
6867012
Wow that sound amazing so their invincible while in Equestria and their more vulnerable outside it.

6867020
Yes, I have their power curve follow the inverse square law, same as for electromagnetism. I posit Equestria as a pocket universe, so their ability to survive drops as distance from the domain wall increases.