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First of all, I am aware that its impossible for a planet with less gravity than the Earth, to naturally maintain an atmosphere with the same terrestrial gases, in an equal or greater proportion. Therefore, this proportion of gases is maintained artificially.

Second, although I have notions of what the ballistic coefficient implies, I have no idea how to calculate it or in what proportion its affected by the atmospheric density and gases of an atmosphere.

Following with this line of thought, we have the force of gravity of the planet X that is 8.04 m / s².

Let us assume then that the atmospheric pressure of this planet, whose atmosphere is being altered artificially, is approximately 2 atm.

Now with all the elements previously presented, I would like to know two things:

  • 1) Would this atmosphere sustain intelligent life in a realistic way? It is necessary to know if a human civilization could develop there.
  • 2) Would the effect of this atmosphere be enough to significantly affect the ballistic coefficient, to the point where its preferable to a civilization that has discovered firearms, have to continue using crossbows for more effective shots at a distance?

Note:Take into account side effects that may present apparently inert gases at high levels of partial pressure, such as nitrogen narcosis.

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    $\begingroup$ I'm just going to tell now that this question will get cut down by the admins they don't like mutable questions change it to one question that's to do with the title don't add more. it sucks i know but that's the way this site operates $\endgroup$ – Creed Arcon Mar 25 '18 at 3:30
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    $\begingroup$ I am aware that its impossible for a planet with less gravity than the Earth, to naturally maintain an atmosphere with the same terrestrial gases, in an equal or greater proportion depends on how much less gravity you have. I think that if the only difference is the gravity, with 8.04 m/s2 it would be doable to have much the same atmosphere. $\endgroup$ – Renan Mar 25 '18 at 4:17
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    $\begingroup$ @CreedArcon, it isn't just this site. All Stack Exchange sites are one-question-one-best-answer format. The reality is that this is not a forum. JAMS, these are two very different questions. Together they are too broad. The question about life on a low-G-high-P world might, itself, be too broad (it might even be a duplicate). And for the record, the only practical reasons for preferring a crossbow over a gun is limited resources for guns. Nothing about the world would ever make crossbows preferrable due to the range + damage + weather benefits of firearms. $\endgroup$ – JBH Mar 25 '18 at 4:55
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    $\begingroup$ (0) There is no need for artificial intervention. It is perfectly possible for your planet to sustain the required atmosphere naturally; see, for example, Venus. (1) At 2 atm total pressure the partial pressure of oxygen would be 0.42 atm, which is all right even for terrestrial humans. Yes, it can sustain intelligent life. Nitrogen narcosis is not an issue for life evolved on that planet, and even for humans it's borderline at only 2 atm. (3) Why would spring-powered weapons be preferable to firearms? Just like on Earth, crossbows would be preferable to firearms only in special situations. $\endgroup$ – AlexP Mar 25 '18 at 5:04
  • $\begingroup$ @AlexP But in the case of venus it has an atmospheric pressure many times greater than the earth, due to the type of gases found in its atmosphere. $\endgroup$ – JAMS Mar 25 '18 at 5:19
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an atmosphere with the same terrestrial gases, in an equal or greater proportion.

78% Nitrogen 21% Oxygen 01% Other stuff (mostly Argon)

the atmospheric pressure of this planet, whose atmosphere is being altered artificially, is approximately 2 atm.

Note that since the partial pressure of oxygen would effectively twice that of Earth, fires would burn faster.

Would this atmosphere sustain intelligent life in a realistic way?

Native life would/could have adapted to it, so there's no reason to say "no" to this hypothetical question. So... yes.

It is necessary to know if a human civilization could develop there.

If these are "humans which evolved on Earth, and then transported to this planet", then the answer is maybe. That's because nitrogen narcosis can begin even at relatively low depths when scuba diving, and 2 ATM of pressure is the same as diving to 10m.

Thus, enough people just might be loopy enough to die off within a few generations.

Would the effect of this atmosphere be enough to significantly affect the ballistic coefficient, to the point where its preferable to a civilization that has discovered firearms, have to continue using crossbows for more effective shots at a distance?

The question is flawed, because we didn't develop firearms because they shot better and farther. We developed them because they were easier.

Note that since there's so much more oxygen at 2 ATM, the gunpowder would burn a lot faster, generating a lot more pressure in the gun breaches. It's very possible that would have delayed the development of firearms (and cannons) until the development of better metallurgy.

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  • $\begingroup$ But in case firearms were developed with better metallurgy, a primitive harquebus would still have problems due to the shape of its projectiles. Wouldnt long and thin projectiles have an advantage due to air resistance? $\endgroup$ – JAMS Mar 25 '18 at 4:41
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    $\begingroup$ We developed firearms because they are handy to breach walls. Try to do it with the crossbow. As of faster burnout of the gunpowder, the recipe is easily adjusted. $\endgroup$ – user58697 Mar 25 '18 at 4:49
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    $\begingroup$ The single-user firearms follow the cannons, just because the cannon was a success in inflicting more casualties, on the greater distance, against better armed enemy. And the original fire__arm__ was a culverin, aka hand-held cannon. $\endgroup$ – user58697 Mar 25 '18 at 5:09
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    $\begingroup$ Gunpowder contains its own oxidiser (saltpeter), it doesn’t use atmospheric oxygen. So the increased partial pressure of oxygen wouldn’t affect its rate of burning in a firearm. $\endgroup$ – Mike Scott Mar 25 '18 at 6:00
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    $\begingroup$ @pojo-guy Crossbows are not silent. They are certainly far more quiet than a firearm, but you're not making a stealth-kill with it (plus bolts travel overwhelmingly slower than the speed of sound, where as the bullet can hit you before you've heard the shot). $\endgroup$ – pluckedkiwi Mar 26 '18 at 16:12
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Would the effect of this atmosphere be enough to significantly affect the ballistic coefficient

No, and at a first glance neither would the higher oxygen pressure.

But you might imagine have large quantities of dry pollen floating in the denser atmosphere. This would require a great care in lighting fires (fireplaces would need something like a flame arrester mesh).

But in the open, firing a gun might be a deadly mistake - unless it had just stopped raining, or the weather conditions or season or geographical features otherwise allowed it. The combination of high oxygen pressure and suspended combustible particles would turn the volume around the shooter into a dust bomb, a weak form of fuel-air bomb. With the shooter at the center.

In Earth atmosphere, it takes some doing for a dust explosion to take place - but if memory serves, a bunch of probationary cooks engaging in a flour battle near cooking fires in a kitchen in Paris was enough to kill one and maim two others, and wreck the kitchen.

Combine some local plant like lycopodium, but more so, and a higher oxygen availability, and wild gun shooting loses a lot of its appeal.

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Firearms were adopted because they were easier to train large numbers of people to use quickly than long or recurve bows. They replaced crossbows because a crossbow bolt, fired from a steel crossbow and drawn with a spanning mechanism could provide about 200J of energy at the target, while an arquebus imparted enough energy to the projectile to deliver 1000J of energy, an order of magnitude difference.

enter image description here

Spanning (or drawing) a steel crossbow. This gets you to 200J of energy

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A Medieval soldier with a firearm. A 1000J of energy can deal with even heavy plate armour

Any crossbow which can deliver that much energy would be either far too large to carry or use in any practical manner, or require such a massive and powerful spanning mechanism that would also be impractical for use in battle outside of special situations.

So regardless of if you are fighting on Earth, the hypothetical planet, or even the vacuum of space (both a crossbow and a firearm will work in a vacuum), a firearm will always outperform a bow.

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