Emrys42

It seems they wouldn't use most the fuels we use, since most of what we use is not even as good as liquid hydrogen. Seems to me liquid Hydrogen would be the worst fuel they might use, while antimatter is the best fuel. Although, if these were hypothetically the worst and best(energy to volume ratio) fuels they are willing to use, then couldn't they have more dense versions of these fuels as well? For example if hydrogen gas is good then a more compressed hydrogen would be better?

Between the Mohs, Brinell, Vickers, and all the other forms of hardness. Along with the lists of each not having every element I am having a real hard time determining the actual hardness of materials. I am designing a game which uses the periodic table to build everything and would like it to reflect the real world as much as possible. The two stats I am trying to figure out for elements it makes sense for(not gases etc) are Hit Points(hardness) and Damage Resistance(Yield Strength), while Yield Strength is not that difficult I am really having trouble with the Hardness. Does anyone have any suggestions(books, charts, or calculations)?

I have been trying to determine(for a game I am designing) what fuels and engines would a technologically advanced interstellar species most commonly use for space travel assuming they want as much energy output as possible for the smallest volume and mass possible. It seems as far as fuel goes hydrogen is the only combustible fuel that makes sense, other then that they might use antimatter, fission and fusion. Are there any other forms they might want to use and why?

Thank you both, the more I learn about the enthalpy of combustion the more it seems a technologically advanced interstellar species would mostly only use hydrogen as a fuel if it was looking for the most enthalpy of combustion by volume and mass. If they weren't using a fuel they would(I assume of course) use fusion or fission engines. Does this seem accurate? If there are other substances then hydrogen they might want to use for fuel what do you think they would be and why?

http://en.wikipedia.org/wiki/Energy_density This wiki page says the "specific energy" of Hydrogen is 123. What is the specific energy of all the elements on the periodic table? It also says the energy density of Hydrogen gas is 0.01005. What is the most dense you will find Hydrogen in the largest possible gas giant(just before it would be considered a brown dwarf star? If your able to answer this for all the gases on the periodic table, even better. http://www.periodictable.com/Properties/A/Density.html This page says the density of Titanium is 4.507, it also says the density of Carbon in graphite form is 2.26 while the density of diamond(also carbon) is 3500. What is the most dense titanium that could be found naturally occurring throughout the cosmos(that we know of)? Thank you for any help you can offer. If specific answers are difficult or impossible a close estimate would still be very helpful. I misspoke on the first question. I am trying to get the specific energy of the gases or other burn able elements on the periodic table. Also someone informed me that the density of titanium will mostly be the same once it leaves a star or black hole, is this correct?