okay, just want to throw this out to you folks, will touch back tomorrow--

what could this be like?  life obviously would be different.  would the universe itself be just a cloud?  no natural clumping of matter that would come with gravitational forces, but instead something magnetic (for lack of a better word)?  

certainly not oxygen breathing life forms as we know it.  

maybe a weak gravitational force works, but nothing stronger?  sorry, my science isn't all there in spots.

The universe is big. Like really, really big. It's the biggest thing you've ever seen, by definition. If you don't have clumping into planets, then there's no life. Things are so far apart that there aren't any stars or heavy elements. It's just a cloud of hydrogen that's very big and very disperse.

We can debate what is required for life all day and all night because we really don't have a lot of data points - but I'm pretty sure that it requires there to be more than just hydrogen gas and hydrogen ions in a formless void.

-Frank

If you want just a world that is effectively without gravity, by IRL physics, effective gravity is zero throughout the inside of a hollow sphere (the pulls in opposite directions cancel out). You can then have atmosphere that stays put because its held inside the sphere. I'd toyed with this idea as a basis for a less silly Spelljammer-type game.
 
If you wanted you could also have the sphere rotate to have centrifugal force provide limited pseudo-gravity just on the inner surface, while not affecting other objects floating inside.
 
A universe without gravity is harder to imagine (what Frank said). The electromagnetic force can do stuff, but electric charges can repel as well as attract so I'd guess there wouldn't be any clumping. The other basic forces like the 'strong nuclear force' and whatever are in theory much stronger than gravity, but operate only at a subatomic range and so have little or no effect.
If gravity is just much weaker, then a gameworld planet is just going to have to be bigger to have the same gravity, but otherwise its business as usual.

well, it's a different universe, another dimension--and a thought experiment.  there wouldn't be "planets" as we know them, since that requires a strong force of gravity.  maybe what i'm thinking of is something like gravity is significantly weaker?  or is only strong enough to work on a molecular level, as opposed to a "stellar" level?

i think the original inspiration for this thought experiment was the fluidic space thing from voyager.  no stars or planets, but life somehow manages to come about.  maybe an analogy would be d&d's astral plane?  just voidstuff, but smaller clumps of matter, nothing larger than a small asteroid, really.

So... a universe where gravity is stronger or the same strength but where the big bang happened with more force or happened relatively recently in the universe's past.

-Frank

For an <#ENVIRONMENT> without gravity, Larry Niven's The Smoke Ring and The Integral Trees are pretty good reads.  (A World out of Time is set more-or-less in the same "universe" but a wholly different setting - on a Dying Earth, millions of years after the other two books but is also a good read).

EDIT: The first two occur in a freefall environment around a black hole with a normal nearby stellar neighbor.  A nearby gas supergiant was torn apart by tidal forces and leaves a "ring" millions upon millions of miles thick with an inhabitable band of o2, water, and other stuff vital for human habitation (and evolution of native plants and animals) in orbit around the black hole, and a society of people descended from colonists who stopped to investigate the phenomena evolves over the course of time.

Quote from: beeber;481285well, it's a different universe, another dimension--and a thought experiment.  there wouldn't be "planets" as we know them, since that requires a strong force of gravity.  maybe what i'm thinking of is something like gravity is significantly weaker?  or is only strong enough to work on a molecular level, as opposed to a "stellar" level?

Are you thinking of gravity behaving functionally identical to electromagnetism, where both forces are governed by (different) massless spin-1 gauge boson particles?

http://en.wikipedia.org/wiki/Gauge_bosons

Quote from: FrankTrollman;481220but I'm pretty sure that it requires there to be more than just hydrogen gas and hydrogen ions in a formless void.

This. If there's no gravity then there's no stellar fusion, no super nova and an empty periodic table, which sucks really.

Quote from: boulet;481322This. If there's no gravity then there's no stellar fusion, no super nova and an empty periodic table, which sucks really.

Isn't the periodic table governed mainly by a Coulomb electrostatic force between the electrons and nucleus?

Quote from: ggroy;481327Isn't the periodic table governed mainly by a Coulomb electrostatic force between the electrons and nucleus?

The diversity of elements in the universe is created by fusion happening inside stars (or when they collapse and then explode).

Quote from: boulet;481328The diversity of elements in the universe is created by fusion happening inside stars (or when they collapse and then explode).

This appears to be the nucleus part of the atom.

What I was thinking of, was how solving the Schroedinger equation for the hydrogen atom (ie. with a Coulomb potential) replicates the patterns of the periodic table.

@TDD, yeah, i think those two niven books are an influence on this--i read them years ago and found the environment fascinating!

as far as the rest, the wiki article might as well been in greek, LOL

but if you're saying we wouldn't have many elements without stellar fusion, i guess that puts a damper on the concept--no cloud of primordial soup or whatever for life (of whatever variety) to evolve and mutate from, i guess.  certainly puts the kibosh on the "fluidic space" dimension bit from trek :nono:

thanks for the input, folks

If the place is an accessible universe, it could get its heavier elements from elsewhere. Someplace that has, for example, some fucking stars in it. If you come up with a bunch of psychobabble about how it's a universe created by material sublimating out of black holes in other universes (or whatever), you can give it whatever size or constituents you want it to have.

Life also doesn't need to have started there, it can have come from another universe and then evolved. With no stars, there would be no photosynthesis. But you could still have living things evolving by collecting the heat from radioactive decay or by breaking down complex chemicals from other universes. Hell, you could go really far out there and have living creatures that soak up hydrogen atoms and fuse them into heavier elements.

If there is no way into the place, it doesn't matter if it exists. If there is a way into the place, you don't need to explain how anything started there, because things can start elsewhere and move in.

-Frank

that would work--the place could be like a petri dish.  stuff gets into that universe, grows, then mutates or dies out.   and yeah, couldn't have photosynthesis, but instead more like those tube worms down at the vents at the ocean's bottom, areas of life based around chemosynthesis instead.  

if i'd have to explain it to players it would end up being a mix of real science and treknobabble, anyway.  but it helps to have more science than babble, IMO

Of course, you could create a nascent universe - one formed not of its own big-bang but by virtue of previously mentioned black holes quantum tunnelling into a space which, in a few ∞ years*, will become a "normal" universe (by accretion of non-strange matter and quantum uncertainty) but for now is your sort of weird universe of quantum foam and little else.  

Perhaps it's already begun in localized places - travelers tell of horrifying "zones" where some fearsome "crushing force" smashes all matter inward into uninhabitable spheres of death.  No-one knows what this terrible phenomena is!


(*=when you're talking about restructuring matter on a fundamental level due to quantum uncertainty, it will "eventually" happen but even on a cosmological time scale, the amount of time taken for matter/energy to restructure on a scale large enough to amass a Singularity - the Singularity - you're looking at essentially Infinite time to pass before that occurs.  But at that juncture if you're just sitting around waiting for it to happen, you have all the ∞ time in the world )