Counterweight artillery, steam cannons, air guns and crossbows. All the stuff you have in the Ancient and Medieval world, with steam and air remaining a curiosity under research at the Museion of Alexandria.

Steam cannons do have potential as the Mythbusters showed. The problem is arranging for a rapid energy transfer to the water.
Air guns suffer from energy inefficiency, but you can use the compressed air and a burning substance in combination.

As for creating the scenario, let's just say saltpeter remained an expensive medicine and you had to be nuts to burn all that money for a slightly hotter flame.

i know this would be alittle off the wall and it is ment to be laughted at, but what about rapid firing crossbows on motorcycles? the mongols biker club could potentually make an empire.



honestly i'm intrigued about the future of armor, the idea of reaction and flex metals has a turly interesting ability.

if there are no guns or explosives then cavalry charges have no real reason to fade away, so replace the horse with a car and you soon have tanks with scythes running round.

ok so it is a little bit mad max but given the limits of what horses can do replacing them with engines is a good idea.

As soon as explosives get employed in mining the availability of metal changes and leads to our current industry with steel machinery. No gunpowder means lower surplus from mining and thus less chances for engines. You also miss the whole gunpowder engine development that was very inspiring.

You can take a simple animal driven carriage and fasten a repeating crossbow and as many sickles as you want on it. This has all been tried one way or another in pre- and early gunpowder times. It would be novel if you take a wheelbarrow instead of a carriage. http://www.lowtechmagazine.com/2011/12/the-ch...arrow.html has a good article on the overall effects of wheelbarrows in China.

To alter the premise somewhat, I suspect pikes, halberds, targets, bows, crossbows, armor, and heavy cavalry would have remained important if gunpowder had somehow not appeared and transformed European warfare over the course of the fifteenth and sixteenth centuries. The knight handsomely encased in steel might well have endured for centuries under this scenario.

I have made a large induction coil gun using a 2000v/100000A at discharge, machine for some show and it was interesting and accelerated things very quickly but as a practical weapon for individual use the power source will be the problem.

I have made many gas powered rigs and made a gun for a bouncing bomb test rig that used a 30cm bore and shot a 30kg load 130m at 6 degrees elevation on 6% power. At 45 degrees on 100% it would have been jaw dropping for home made artillery and all based on nitrogen and all very easy to make.

CO2 is also used in mining where you can use effectively 'sticks of dynamite' that are in fact CO2 units that you burst in holes in the rock, so mining does not have to use explosives, though the acceleration of available technology due to explosives is a very good point.

Party pooper as it may be.` Compressed gas weapons would be the simple and effective replacement to gunpowder.


Tod

compressed gas arrow guns, flame throwers/Molotovs, poison/incapacitating gas, improved shield wall (a la Riot Police)

Electric swords/spears/pikes, sonic weapons, needle guns, gyrojet rounds

paintball guns with acid/anesthetic/poison, etc


and most fearsome of all... SHARKS WITH FRICKING LASER BEAMS

Not intending to spoil the the what-if scenario completely, then a modern world without gunpowder - or at least some other explosive - is not conceivable. Reduced to its basics a gun is nothing more than the applied principle of thermodynamics - using the rapidly expanding gasses from a chemical reaction (an explosion) to build up a high pressure in a confined volume (the barrel of the gun) thus acceleration a projectile by exerting a force on it. Any chemical reaction quick enough will do, or in fact as some have already suggested, ordinary compressed air can be utilized in the same manner though it results in somewhat more unwieldy weapons (think compressing the air as opposed to just loading a premade shell). And it is not just weapons which makes use of these priciples - any kind of internal combustion engine or steampowed one for that matter also does. The basic science is simply to much a part of the modern world to be eliminanted from the picture - and turing those principles into nasty weapons are simply to easy for it not to happen even if we tried to imagine some kind of moral or religious taboo against it..

Nonetheless, its always fun to explore the idea of these alternate worlds.

To consider your original question; how a world much as we know it, just excluding firearms, would reflect on armour and fighting? Well, for one thing we are able to make personal armour of a much higher strength-to-wheight ratio than anything historically possible - and, using standardized elements and sizes, in an relatively quick industrial manner. Turning out breatplates for use against crossbows and edged weapons is not much different from the vest currently used against bullets and scrapnel - in fact ceramics, kevlar and various composites would propably most often be the material of choice despite the advances in metallurgy..

Chosing a level of protecting for the individual soldier, as well as overall use of these troops, two major considerations comes into play. What kind of weapons they are up against is the first obvious factor as I'm sure anyone will agree on, but almost as important is the wheight, value if you like, that the surrounding society puts on human lives as opposed to material costs. This, in my opinion, will make fighting and equipment differ from that of previous centuries to a much higher degree than any specific advance in material science or tactics and has been left out of the discussing so far. If not already apparent earlier, then WWI showed what industrialized warfare really is. The pitched battles of the industrialized economics of supplies and output rather than events on the battlefield. Armies of relatively untrained mass-conscripts can be turned loose and equipped so effectively that it is just a numbers game. Given a society with infrastructure and industry as we know it, it doesn't really matter if rifles are replaced with either an airpowered equivalent or some sort of rapidfire crossbow contraption. Speeds might be somewhat down on the battlefield, both in case of rounds fired by infantry and the mobility of heavier weapons (replacing tanks with gunturrets and artillery-pieces with some, due to their support machinery, larger pieces capable of similar action, be it via electro-magnetic or air/steampowerd projectiles), but it doesn't change the big picture.
It is just to easy to take a vast number of lives in very little time today, not even considering NBC-weapons or similiar. Just to pick one example, consider the use of incindiaries. Even if not thinking bombardment from any kind of flying contraptions or large-scale electric railguns, trebucets or similar with longer ranges, simple flamethrowers, suitable protected, could effectively neutralize any larger concentration of troops massing for close combat. Sure the opposing army would come up with similar tactics if not wiped out right away, but the point I'm getting at is that of the offensive versus defencive capapilities in modern warfare which are clearly unbalanced: The potential killing power of any individual soldier simply prevents any kind of chivaleric face-to-face fighting or large-scale close combat from being the norm. Perhaps the deciding factor isn't even the support industry, rather that it enables conscripts to kill professionals. Of course there is and always will be a difference in effectiveness due to training, but though peasents could also be levied en masse in the middle ages, they hardly had much chance against the professionals of that day, noblemen and mercenaries. Being able to pick of someone from a distance with weapon where you more or less just point and trigger it makes a huge difference as opposed to meeting them with a pitchfork. The English longbows or the Genovese crossbows didn't quite make it, their rate of fire was not sufficient or they required some level of skill in use as well as craftmanship in their production, but it was a first. Once firearms were sufficiently effective and easy to use as well as produce, one of the most important factors in warfare had become how many men could be equipped and supported in the field, not the individuals themselves. This would of course not differ if the weapons of choice were something different than those associated with gunpowder.

Just to wrap up this long post, I actually think armour - at least the munitions grade supplied to the masses - would be quite prevalent, though there would not be much of the completely enclosing high grade, as this could offer little extra protection against heavier weapons. A simple flak-jacket or cuirass if you like, could make more of a difference in terms of survival if the rate of fire or kinetic energy of induvidual projectiles were somewhat down as compared to what infantry of today are exposed to. A simple cost-benefit analysis would see to that. When bodyarmour were finally outfased some 150-200 years ago (think mounted cuirassiers) it was of it being too expensive (not to mention heavy) compared to the number of cases where it would make a difference. Some elite troops have been issued armour in the recent past, but basically it has only resurfaced in wider use again (think recent conflicts in Iraq and Afghanistan) once the costs of issuing it were favorable as opposed to not doing so - which may be as much due to political considerations as a merely economic argument. Nonetheless it is still valid analysis.

So, massproduced armour, most likely a helmet and protection for the torso/abdomen but not the limbs as a standard. If the scenario also excludes the use of explosives (landmines, bombs, granates etc. ) helmets with a wide brim - think kettlehats or sallets - would be the norm as there would be no risk of deflecting scrapnel which is basically the factor deciding the design of helmets in our world. More enclosing armour is unlikely for regular infantry unless the level of medical treatment (basically survivability of blodloss/infections = damage to the limbs ) has been tweaked. It would just be a thing large left unused, as it was more likely to cause discomfort than save your life. One probably has to go all the way as to banned serious development of projectile-weapons as such if extant armour should see wider use..

Unfortunately for us lovers of fine armour, in this altenate scenario warfare and weaponry would still be a matter for states and corporations outfitting the masses, leaving little credability to the idea of mastersmith toiling away to produce individual masterpieces..

I wouldn't say that gunpowder, much less modern firearms, allow "conscripts to kill professionals." Properly drilled and experienced professionals always had the advantage over barely-trained peasantry, especially as the numbers increase (an untrained bum might stand a chance against a lone soldier but when it's 100 bums against 100 soldiers there probably wouldn't even have been a fight). It's worth noting that recent development in command, control, and communications as well as training and tactics have allowed professional military forces to score staggering kill ratios against less well-trained opponents; the one thing people tend to forget about Black Hawk Down/Mogadishu is that the tiny force of Rangers and Deltas inflicted over ten times their own number in casualties. Without air support from the Little Bird gunships the ratio might not have been that high and indeed the stranded force might have been overrun, but in all likelihood they would still have brought down several times their number in Somali attackers as they died fighting. Similarly, against soldiers who had a really good idea of how to use the musket and bayonet, even musket-armed peasantry isn't going to do much good without an overwhelming advantage in numbers.


That brings us to one funny fact: we don't use gunpowder anymore in most of our firearms, not in the sense of the original black powder. The propellant we use today is usually a nitrocellulose-based mixture that gives off much less smoke and causes less fouling than black powder. So today's world without black powder? Hardly any difference at all. Our reenactment groups would look quite different but once it gets to modern weapons it'd just be pretty much the same thing all over again.

There was a cute basis for a roleplaying game called “Out of a violent planet” that was an attempt to combine plausible aliens with “humans are special”. Essentially the conceit was that all sentient aliens were psychic, so when aliens encounter humans they have trouble dealing with them , because they can’t accept that non-psychics are sentient, but eventually start referring to humans as “murder apes” due to their unique ability to make up for their weak, toothless and clawless bodies, and lack of psychic abilities by perverting science to make tools (which no one else needs) especially tools for putting holes in other creatures (most other species settle arguments by mind controlling the other party).

The parts of this discussion about how if gunpowder did not exist, we would just find an alternative way of perforating each other reminded me of the setting.

I forgot to mention that the only really silent pistol in the world is a Russian model where the expanding gases drive a piston that in turn drive the bullet out of a short barrel; none of the gases are supposed to escape the cartridge, hence no (or very little) acoustic report. The principle was obviously inspired by internal-combustion pistons (such as those used in automobile engines) and I can't conceive of a modern civilisation that wouldn't want to take advantage of this if they had no other means of chemically propelling their projectiles. Of course, without encapsulating the gases, we'd just get a close equivalent to guns with the exception that the fuel and oxidiser components of the propellant would have to be fed into the chamber separately rather than being combined in a granular/caked form.

Here's what I'm thinking (if we assume that technological progress continued as it did in reality, just with no gunpowder.)

The 1500s would see a surge in the development of extremely high quality armor for both men and horses (plate armor was already becoming highly articulated and complex by the early 1500s.) So, basically, this already happened, except in real life armor just got heavier and heavier to protect against gunfire until law of diminishing returns forced cuirassiers and lancers to switch to 3/4, half, breast/back/helmet, and finally no plate at all, switching to buff coats.

Without the guns, there would have been no reason to abandon full plate armor, so I imagine in this alternative scenario, we'd have fully-armored cavalry and infantry in high quality articulated armor for hundreds of years later, maybe all the way up until the mid 1800s. The styles of fashion would undoubtedly change, but the armor would retain its basic form. (In fact, as armor design has always mirrored clothing design, it'd be a pretty cool exercise to try to imagine what the plate armor of the 1700s and 1800s would look like, from what we know about the fashions of the time.)

As soon as electricity becomes developed to a sufficiently high level, expect the armor to be abandoned as soldiers come face to face with electrical weapons and get electrocuted to death inside their metal shells. Also they would be cooked alive by flamethrowers and other such devices. So by 1900 I expect it would be more or less like the 1900 of reality, just with no guns and more electrical projectiles, compressed-air weapons, and flamethrowers (which would be a mainstay of the battlefield).

Lower tech you'd see Flamethrowers, Poison gas weapons, Steam-tanks. Once Steam has arrived you could just boil people with it

At a higher tech you'd figure out a man portable way to make small pieces of metal move really fast, there are a ton of options, and you are back to guns again

S. M. Stirling made an attempt in his "Dies the Fire" series to outline a physics that could support not rapid chemical reactions without unpleasant side effects like putting out the Sun, does an ok job, but it's just too hard to close all the "make bits of metal move really fast" methods IMO...