D&D 5E Unearthed Arcana: Travelers of the Multiverse

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dnd.wizards.com

Looks like Spelljammer and/or Planescape is back on the menu!

 

[Paul Farquhar]

But they were celestial bodies that moved differently.

And that's what made the different: Planets moved (along the ecliptic), the position of stars was fixed relative to each other. That's what made them stars. Neither type of heavily body appears to be "free floating", they all move in fixed paths.

It is just about possible for the human eye to resolve Venus (when full) as a disk, wheras stars are only ever visible as diffraction patterns. It's difficult to see what conclusion an ancient astronomer could have drawn from that, even if they had made the observation (there is no record of anyone before Galileo noticing). The Galilean moons of Jupiter are just on the edge of naked eye visibility too, but again no one is on record as having noticed them.

 

[Chaosmancer]

And that's what made the different: Planets moved (along the ecliptic), the position of stars was fixed relative to each other. That's what made them stars. Neither type of heavily body appears to be "free floating", they all move in fixed paths.

It is just about possible for the human eye to resolve Venus (when full) as a disk, wheras stars are only ever visible as diffraction patterns. It's difficult to see what conclusion an ancient astronomer could have drawn from that, even if they had made the observation (there is no record of anyone before Galileo noticing). The Galilean moons of Jupiter are just on the edge of naked eye visibility too, but again no one is on record as having noticed them.

But again, the ancient Chinese did conceive of them as objects floating at a vast distance. This is an undeniable fact. You can say they had no real evidence for their theory, but since they had the theory and it was competing with two other different theories, they had to have something that convinced them to support the theory.

I also hesitate to accept there being no record of someone else noticing being evidence that no else did notice. Not only is the North-Western World notorious for not acknowledging the accomplishments of other groups (very few people seem to know about Ismail al-Jazari for instance, who invented and built the crankshaft, camshaft, and robots in 1206) but the Mayans and many others with rich histories of astronomy had their records destroyed by invaders. So if records did exist, they were lost.

This is not to belittle Galileo. He did discover amazing things that people in his section of the world did not know. But the more I learn of world history, the more skeptical I become of the idea of things the world at large didn't know or suspect at any point in the history of the planet. There are many things we are finding out where known or discovered long before we think they were, by other people around the globe.

 

[jasper]

Neither does anything else except making an interesting PC.

But exploring a bizarre biology is one of the routes to making an interesting PC. And as someone who has already had Slime NPCs, getting a slime PC race is welcome

I don't need the bizarre to make a interesting PC. Anyone can make a interesting PC with bog basic human.

 

[Chaosmancer]

I don't need the bizarre to make a interesting PC. Anyone can make a interesting PC with bog basic human.

I never said you needed it. I said that it was one of the ways. You don't need swiss cheese to make a grilled cheese sandwich, but using swiss cheese is one of the ways to make a grilled cheese sandwich.

 

[SkidAce]

I never said you needed it. I said that it was one of the ways. You don't need swiss cheese to make a grilled cheese sandwich, but using swiss cheese is one of the ways to make a grilled cheese sandwich.

Instead of cheddar or american?

 

[doctorbadwolf]

The stars did not move, that's the point. The only available evidence indicated that the position stars relative to each other was fixed. It was not possible to observe proper motion of stars until the invention of the telescope, and even then it was shockingly difficult, as they where much further away than anyone could have imagined. Given that the relative positions of stars was observably fixed, the dome hypothesis was actually a better hypothesis than a free floating hypothesis.

Um…Ptolemy posited a model in which the stars move around the Earth. Only people who thought the world was flat, which was not a widely held belief after about 500 BCE, thought the stars were holes ina dome. That was not a thing in the Middle Ages.

Geocentric model - Wikipedia

en.m.wikipedia.org

Also Aether was posited by Aristotle, as were crystal spheres surrounding the Earth.

 

[Demetrios1453]

Um…Ptolemy posited a model in which the stars move around the Earth. Only people who thought the world was flat, which was not a widely held belief after about 500 BCE, thought the stars were holes ina dome. That was not a thing in the Middle Ages.

Geocentric model - Wikipedia

en.m.wikipedia.org

Also Aether was posited by Aristotle, as were crystal spheres surrounding the Earth.

The article you link, as well as the crystal spheres you mention, are what I assume what he was trying to say. The stars were believed to be attached to the outermost crystal sphere. Granted, it's not quite "holes in a dome", but it's fairly close...

 

[Demetrios1453]

The stars did not move, that's the point. The only available evidence indicated that the position stars relative to each other was fixed. It was not possible to observe proper motion of stars until the invention of the telescope, and even then it was shockingly difficult, as they where much further away than anyone could have imagined. Given that the relative positions of stars was observably fixed, the dome hypothesis was actually a better hypothesis than a free floating hypothesis.

I think you're meaning the stellar parallax, not stellar proper motion. Proper motion was already suspected in ancient times, and was proven as time went on and certain stars such as Arcturus had obviously shifted from their position over the centuries.

Stellar parallax was the real bump in the road for heliocentric models. If the Earth moved around the Sun, the stars would be seen to shift on a yearly basis as the Earth moved in its orbit, but no such movement was ever observed in ancient, medieval, and early modern times, simply because the stars were so much farther than anyone suspected. The lack of an observed stellar parallax was the ultimate and conclusive argument against heliocentrism, and it was the rock upon which Gallileo's defense foundered. It wasn't until 1837 that telescopes were powerful enough to detect stellar parallax and the heliocentric model was definitively proven (although by that point few believed otherwise).

 

[doctorbadwolf]

The article you link, as well as the crystal spheres you mention, are what I assume what he was trying to say. The stars were believed to be attached to the outermost crystal sphere. Granted, it's not quite "holes in a dome", but it's fairly close...

Closeish, but definitely not the same. The stars moved. People knew the stars weren’t all in the same places as they were in the dusty writings they studied.

Like…the positions of the stars were recorded, the fact the stars were different in different places was discussed, astronomers compared contemporary stellar alignments with ancient stellar alignments.

And there were many different proposed models for what it all meant.

Anyway, this all came about because of a discussion of the space in space opera, so Ancient Greece and medieval Europe is purely tangential. It does’t matter what the ancient or medieval understanding of the cosmos was. Players that want dnd space opera want to play D&D in Space, not a weird cosmic ocean of flammable nonsense.

 

[Paul Farquhar]

Um…Ptolemy posited a model in which the stars move around the Earth. Only people who thought the world was flat, which was not a widely held belief after about 500 BCE, thought the stars were holes ina dome. That was not a thing in the Middle Ages.

Geocentric model - Wikipedia

en.m.wikipedia.org

Also Aether was posited by Aristotle, as were crystal spheres surrounding the Earth.

Aristotle was not a scientist - he did not make predictions that could be tested by experiment. So, without any evidence to either support or refute, his aether sat on the shelf gathering dust for many hundreds of years (also see: atom). When evidence that light was a wave started to become overwhelming at the beginning of the 19th century scientists thought there had to be a medium for it to propagate through, so they dusted off Aristotle's aether. But, having revived the idea, Michelson and Morley set out to look for it, and failed to find it. Thus, the idea was thousands of years old, but only "science" for less than a hundred.

Ptolemy, on the other hand based his model on observations, and yes he, along with most educated people for most of recorded history, knew the Earth was a sphere, so his "dome" that held held the stars was also a sphere. Ptolemy's model, with it's fixed stars, was in regular use in the West for a couple of thousand years (with patches) and was declared "True" by the Church.