I remember seeing this in a thread (or maybe on Reddit?) a while ago (originally it was suggested to be gaseous hydrogen which made no sense when we ran the numbers). However I've not seen a source linking this back to official lore and I personally dislike it - not on any scientific grounds, I'm just attached to my WWII-analogue ship classes and tonnages.
Here ya go.
https://www.reddit.com/r/aurora4x/comments/7y9la5/whats_a_ton/dui2wwc?utm_source=share&utm_medium=web2x&context=3
Excellent, thanks.
Thinking about it, 14 m3 being one "ton" seems in the ballpark of tons being literal mass. Aluminum for example has a density of roughly 2.7 tons/m3, so for 14 m3 of volume to contain one ton of mass would imply about a 3% volume fraction of an aluminum alloy. My recollection from some investigation I did a while ago was that most ships had average mass densities in the range of 1% to 10% of the theoretical density of the primary structural material (obviously there is space for crew, component access, actuating mechanisms, wiring/cabling, etc.).
Does this mean anything important? No. Am I pleased that my personal headcanon can be mathematically justified? Of course!
I think that we have to assume that Duranium is some form of metal like compound that can be combined with other TN materials to form into many different types of materials with different properties. Duranium is what most stuff is actually made of in Aurora in terms of physical properties and especially ship hulls and many times armour.
In terms of crew I certainly assume that automation is a bit better in Aurora than in most equally sized ships of today.
Also... Mass is not important for Aurora in terms of ship movement, ships probably don't have much of any thrusts other than for very fine adjustments for docking. Travelling the stars in Aurora is purely based on ships volume, ships actually can weigh any amount of actual mass.
When I envision ships in Aurora they don't look much like most sci fi ships of most lore, certainly not with an engine at the back. I envision ships looking more like if they use and Alcubiere (
https://physics.stackexchange.com/questions/172699/the-effect-of-multiple-alcubierre-rings) drive or something similar where the "fuel" is not the actual driving force but the stuff that sinks the ships into the Eather. This makes the ships sort of fall through the Eather or surf it by displacing it in real space by micro displacement in space. Ships sort of blink in and out of existence in our universe and that is how the can instantly travel from one point to another without incurring any actual thrust or G force on either the ship or the crew inside it.
We also need to assume that a ship automatically adjust its relative speed to any gravity object it is close to, this is also why a ship don't have to alter thrust in order to match it's relative speed as it get's closer and closer to another object that exerts a large enough gravity force, the larger the object and the closer you are too it the ship will match the relative speed to that object without effecting either the ship or the crews energy "Magic". This is also one reason why objects larger than 500t can land on planets and other bodies as gravity somehow interfere with the drive systems.