The Alchemist has the following Grand Discovery available at 20rth level.

    Eternal Youth: The alchemist has discovered a cure for aging, and from this point forward he takes no penalty to his physical ability scores from advanced age. If the alchemist is already taking such penalties, they are removed at this time.

    The Wizard has the following Arcane Discovery available at 20th level.

    Immortality (Ex): You discover a cure for aging, and from this point forward you take no penalty to your physical ability scores from advanced age. If you are already taking such penalties, they are removed at this time. You must be at least a 20th-level wizard to select this discovery.

    I could see these being adjudicated one of two ways.

    1) They grant true immortality and the character lives forever unless killed.

    2) They keep the character eternally youthful but the character dies at the maximum age for their species.

    How do most people rule this?

Do you want there to be a difference between Immortality and Eternal Youth? If so, then one option could be that Immortality keeps you at the age when you became immortal and Eternal Youth keeps you at age 18 until you reach the maximum age of your species.

But generally, these are interchangeable terms.

Yeah, these look like the same thing to me. Cures for aging. You could have them work differently like Spinachcat said. Or you can just top out the character's apparent age at, say, the top of the Adult category for the wizard's Immortality effect, while Eternal Youth stops aging and then the character's apparent age decreases a year for each year that passes, until it stops at 18 or so, so they don't go full Benjamin Button.

Even if you accelerate time a lot, how often does dying of old age actually come up in D&D games? (Okay, it did happen if you used aging caused by spells, but that was usually ignored in my experience)

It's certainly a factor in games like Pendragon or Ars Magica but even long D&D campaigns rarely seem to go more than 20 years of game time (at least in my experience).

But I would go with 1). If you don't age, then your body likely wouldn't break down. Though I think eventually you would soak up enough backround radiation for that to kill you.

In Mystara, thanks to the potion of longevity not having any chance of failure in BECMI (as opposed to AD&D, where there was a 1% cumulative chance it would fail and undo all the removed aging) there were a lot of effectively immortal people in the high magic nations like Alphatia and Glantri

I've never had characters continually played for long enough for "aging" rolls to matter.

I admit one of the sounder ideas of GURPS 4th was to take the Aging disadvantage off the table.  You want to play an elderly character?  Then design the character to have reduced capabilities to suit.

You stay young, but ultimately die when your natural time is up. IMC true Immortality is a pipe dream many have researched, and if and when it occurs, it is the result of a curse or some magical experiment that defied the laws of nature and/or went terribly wrong (e.g. lichdom, vampirism, etc).

That is the by-the-book 3e take on immortality (for the otherwise mortal). It does not appear to be stated in the Pathfinder SRD though, so... do what you want!

Quote from: JeremyR;731641Even if you accelerate time a lot, how often does dying of old age actually come up in D&D games? (Okay, it did happen if you used aging caused by spells, but that was usually ignored in my experience)

I've seen it come up a number of times in AD&D, although Haste or a Ghost were invariably the culprit.

Similar to what others have suggested, I'd treat Eternal Youth and Immortality differently, with the former keeping you at the young age bracket until maximum age is reached (at which point you die), and the latter allowing aging through the age brackets, but not dying when maximum age is reached.