World Axis Cosmology

Question

I have a few uncertainties concerning World Axis Cosmology.

Are all planes alternative universes? (That is, there is no way to travel physically from one to another - only by portals and magic.)

Is mortal world considered a planet or there is some "world's end"? (If we want to be specific, mortal world is post spellplague Toril.)

Are there any stars and moons in mortal world?

Answer 1

Your key resources on getting more detail than the Dungeon Master's Guide offers are the Manual of the Planes, and supplements like The Plane Above and The Plane Below (for the Astral Sea and Elemental Chaos, respectively).

The planes are not each separate universes. Travel between them is another matter entirely.

• As I write about in What are the planes of D&D 4e? Where did they come from, and how are they connected?, the Shadowfell and Feywild are echoes of the Mortal World, and the Mortal World is still physically connected to them at many points, such as in the hearts of the wildest forests and within the deepest and darkest caves. At this points, you can end up walking from the World to one of those echoes or back again, without portals or magic.
• The Astral Plane and Elemental Chaos are very much within the same universe as the mortal world, which was made in a space right between them. Getting to them by conventional travel however will be tricky, as they are infinite in size. The topology may not make sense here. Don't think too hard about it.
  • The World is still intimately connected to the Elemental Chaos in the most elementally wild and chaotic locations, and you could travel through those just like you could to the echoes. However this is usually more environmentally hazardous, considering we're talking about the elemental extremes: you'd be heading through the heart of a volcano, or deep into the ocean, or into an enormous ages-old storm, or so on.
  • One could ask the question: "what if I hop on a rocket ship and just start heading in one direction for a while?", but that's something the lore leaves open for you to explore the answer to in your own campaign.

The Mortal World, strictly speaking, refers to a little spherical ball of chaos and life that the Primordials created and the Gods stabilised. It's a planet with finite surface area.

There are stars in the sky, but what they are is less clear. Are they magic twinkling out from the Astral Sea? Are they burning balls of gas? Are they lights suspended in a ball around the space the Mortal World sits in? Are they the eyes of aberrations peering in from the Far Realm? Nothing in D&D 4e's lore cares to answer this cleanly, preferring to leave room for you to make up something fun.

Are there other planets? Certainly the lore encourages speculation that the Feywild and Shadowfell may just be two of many echoes of the world, but what that means for other planets isn't clear.

Answer 2

Looking at the handy cosmology map on page 161, we see what looks like a spherical earth flanked by spherical other-earths: The Shadowfell and Feywild.

I have always treated the Demi-Earths to be separate plane, and only allow planar travel to them. However, I must define parallel worlds differently than others. In my opinion, a parallel world has an alternate person for each Earthling (Like in the Doctor Who episode 'Age of Steel,' where Pete is still alive, Jackie's divorced, The Doctor doesn't exist [or is dead] and Rose is a dog). From what I can tell, the Demi-Earths are more like copies of the locations, but not (necessarily) the people (the 4e Tomb of Horrors handily illustrates this).

In summary: No, I don't think you can get to other planes by getting on a spaceship; Yes, Earth (or Toril, Oerth, or whtever else) is a planet (sounds a little stupid, actually, when I put it like that), and I don't think that either Demi-Earth is necessarily parallel.

Yes, there are stars, or else how would there be a Star Warlock Pact?