I am having a bar fight instead. 8 space marines are getting hammered when all of a sudden a cult shows up and starts a bar fight in the zero-G bar where the marines are. The cult is also rather inebriated, so it is a pretty fair fight. The marines are trained in zero-G combat and have enhanced reactions. The cult is a bunch of men and women who can throw punches and have bad tempers. How would the zero-G environment affect the result of a classic bar fight (i.e. can I still smash a bottle and use it to stab someone)? I’m looking for answers from people with first hand experience in bar fights and or zero-gravity, having never been in a serious fight in my life.

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    $\begingroup$ I don' think anyone here had a first hand experience with a 0-g fight... I hope you are already familiar with this classic example $\endgroup$
    – Alexander
    Dec 15, 2020 at 19:36
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    $\begingroup$ :Zero-g" and "bottles" are somewhat incompatible. $\endgroup$
    – PcMan
    Dec 15, 2020 at 19:57
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    $\begingroup$ Most real barfights are both unspectacular, fast, and confusing -- even before the bad lighting. Don't go for reality. $\endgroup$
    – user535733
    Dec 15, 2020 at 20:05
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    $\begingroup$ When you say "space marines" and "alien worship cultists", are you referring to Warhammer 40k where you have magically enhanced space marines who can punch through brick walls with their bare hands vs cultists who've been twisted into demon like beings by the Chaos Gods or do you just mean two rival factions of mundane humans that just so happen to share names with a popular franchise? $\endgroup$
    – Nosajimiki
    Dec 15, 2020 at 20:16
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    $\begingroup$ What @L.Dutch-ReinstateMonica is trying to get at is that the problem is that your questions are too story-based. Our job here is to take a specific question (e.g. "how would microgravity affect a bar fight?") and answer it. It is not to write your story for you. As a result, it's generally recommended that you keep extraneous elements of your story (e.g. that the attackers are an alien-worshipping cult) out of your question. $\endgroup$ Dec 15, 2020 at 20:52

6 Answers 6


Zero-G isn't a great place for a fist-fight. Or a bar, really.

Sucking whiskey through a straw from a collapsible bulb does not make for a particularly pleasant drinking experience, and any ah... fluids that might come about from having gotten hammered will float all over the place. Into ventilation systems. Into your squadmates' faces. Ew. Plus, having to push people passed-out-drunk out of your way just to get to the head?

If there's going to be a common area to drink and eat, it really seems like it'd be in a rotating section of the space station.

But all that aside, it's also not a great place for a fist-fight (let alone improvised weapons). There's the fluid issue again (break someone's nose? Enjoy wobbling spheres of their blood flying all over the place), but also, as a nameless Mass Effect sergeant put it, "Sir Isaac Newton is the deadliest son-of-a-bitch in space!" So if you hit someone without properly anchoring yourself, as much of your energy goes into shoving you backwards as into your opponent. So most of your haymakers are going to be operating at half-strength, notwithstanding intoxication.

That same intoxication is going to make the mental vector-math needed to make sure you're pushing off the right surfaces and grabbing the right handholds nearly impossible, of course, so what you'll probably have is a bunch of relatively aimless flailing at one another, unless everyone's boots are magnetically locked to the floor or something.

Breaking a bottle to use as a dagger in microgravity seems almost suicidally stupid, though. I can't imagine that any bar in zero-g would stock glassware at all, and would keep its drinkables in plastic containers. Even on earth, if you drop or break a glass bottle, tiny shards and fragments get everywhere and take forever to clean up. Imagine glass dust floating around in space! Inhalation hazard, eye hazard, navigation hazard, filtration hazard, all at the same time.

So a zero-g barfight would be dramatically different than a barfight on earth, would probably not be possible for heavily intoxicated participants, and probably wouldn't happen at all, because the bar wouldn't be in zero-g.

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    $\begingroup$ For those of us without a nautical vocabulary, "the head" means the toilet. $\endgroup$
    – cowlinator
    Dec 16, 2020 at 7:40
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    $\begingroup$ Once we start living in space, bars will probably be the first thing to pop up ... $\endgroup$ Dec 16, 2020 at 18:41
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    $\begingroup$ " Plus, having to push people passed-out-drunk out of your way just to get to the head?" - actually, that might be easier in 0-g than on Earth... $\endgroup$ Dec 17, 2020 at 10:07
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    $\begingroup$ We've had spacebars for years though $\endgroup$ Dec 17, 2020 at 20:40
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    $\begingroup$ @MikeG Did you just. $\endgroup$
    – jdunlop
    Dec 17, 2020 at 22:40

Jdunlop is right that you do not want a bar in a zero-g section of a space habitat... but that does not mean there is not a good reason for a normal-g bar to suddenly become a zero-g arena for a bar fight. If the bar was never intended to become zero-g, it may still have all the hazards one would expect of a normal bar: glass bottles, open containers full of various liquors, etc.

One of the interesting things about this scenario is that you have two factions with vastly different backgrounds. While your cultists, like most people, have probably never even thought about how to fight in zero-g, the space marines would have spent a significant portion of their basic training learning to do combat in unusual gravity situations. Whether the Space Marines are legitimately out matched or just so drunk it seems like a good idea, one of them may believe that they could get the upper hand specifically by killing the gravity and relying on their space marine zero-g training to carry the day.

And for the most part it would work...

In zero-g, if the cultists still thinking they can tackle, punch, and kick their way into a win they will quickly find that they have become a greater threat to themselves than the space marines. People who have experienced zero G often comment about how surprising the force of their own inertia is despite feeling weightless; so, I suspect many of them would end up injuring themselves slamming into things at angles they don't know how to control and with an amount of force that they do not expect.

Having seen my fare share of drunken college brawls, I can say that a person who is trained to fight a certain way will still typically fight that way farely well even when drunk. Wrestles still wrestle, boxers still box, untrained noobs still flail around like untrained noobs, etc. The biggest differences between a drunken combatant and a sober one is that drunken combatants are more likely to not notice things like walls and furniture; so, then tend to do their well rehearsed moves that they know perfectly well right up to the point that they run into something. The other big difference is that drunken combatants are less likely to know when to "pull their punches". This is a double edged sword in the since that it means they will often hit harder, but it also means they will often over commit to attacks leaving themselves either vulnerable to counters or simply attacking in ways that they injure themselves too.

While I do not believe any style of martial arts exists yet to cover zero-g fighting, we can make some predictions about what it would look like based on how space-walk training works. Basically, you stop relying on friction to create counter forces, and instead rely on hand-grips and wedging yourself into places. So, while the cultists would mostly be floating around flailing wildly, the Space marines would fight such that they always keep one appendage gripping or wrapped around something for stability. In doing so, they could still effectively strike their opponents without particularly endangering themselves. Having rehearsed these combat habits, they would also naturally be compensating for their lowered situational awareness since their whole fighting style would be based around not taking the environment for granted and hanging onto things for extra support. So, my guess is that the intoxicated space marines would still be relatively capable combatants in the environment even if they are not fighting at 100%.

As for using weapons, glass bottles are not a great idea because of the debris, but I could see pool sticks being very useful. Apart from the mechanical advantages of hitting someone with a stick vs your fist, they will also be useful should you get flung out into the middle of the room since it could be used either to push yourself back to a grippable surface, or to help slow you down before running into something.

In the end, the Space Marines will probably get courtmarshaled on who even knows how many violations, but my money is on them to win the zero-g fight hands down.

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    $\begingroup$ I would comment that if the bar was never intended to become zero-G, making it zero-G should be more difficult than a soused space marine can manage. Even assuming magical gravity plates rather than spinning, even emergency shutdown would require multiple authentications, probably not from within the bar. $\endgroup$
    – jdunlop
    Dec 15, 2020 at 23:29
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    $\begingroup$ @jdunlop (warning: TV Tropes link ahead) Not necessarily $\endgroup$
    – Erbureth
    Dec 16, 2020 at 13:16
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    $\begingroup$ Right. Soft Science universes tend to be much better at inventing super technology than making it tamper-resistant. $\endgroup$
    – Foo Bar
    Dec 16, 2020 at 14:01
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    $\begingroup$ @jdunlop This can be explained without an insecurity system by simply assuming that the Space Marines (or atleast the squad leaders) are privileged users. Since it is the duty of the space marines to protect the space station, they would could already have the credentials to manipulate gravity plating anywhere on the station simply because of its usefulness as a non-lethal crowd control measure. If gravity control is seen as part of a ship/station's defensive systems, then making an overly difficult authentication system could be considered a bad thing. $\endgroup$
    – Nosajimiki
    Dec 16, 2020 at 15:50
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    $\begingroup$ @ErburethsaysReinstateMonica I'm amazed that link doesn't have my favourite insecurity system trope - which is that a gun can be used to either lock OR unlock an electronic locking system depending on what the protagonist needs - THE LOCK WILL KNOW $\endgroup$ Dec 17, 2020 at 12:59

When ice hockey players fight, they grip each other's collars with their other hand before they start punching, to stop themselves being pushed apart by the force of the blows. I would believe this happening in space too.

In zero G ordinarily you would hold on to the furniture with your hands or feet if you're not trying to get somewhere. But if you're too mad to wait for the enemy to come to you, you could leap at them, grab at them with one arm, and start punching with the other. You'd have to hold on tight, though; if they can get you to let go, and you're not holding the furniture, they can throw you slowly but firmly at the opposite wall.

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    $\begingroup$ +1 for reference to a real-life analogue. $\endgroup$ Dec 16, 2020 at 20:05
  • $\begingroup$ What a great point ! $\endgroup$
    – Fattie
    Dec 17, 2020 at 14:10
  • $\begingroup$ This, it makes a lot of difference if the fighting parties are used to 0-g or even fighting in 0-g or if they have to find out how to do it, while they are doing it. $\endgroup$
    – Ivana
    Dec 17, 2020 at 19:39

That has some interesting possibilities.

First, if industry or commerce gets into space, people have to build all of that, so they might have a bar to relax after work. Gotta keep space from getting too boring...

There wouldn't be any glass bottles. If there was a bar, drinks would likely come in some form of squeeze tubes. Can't suck liquid out of a glass bottle in zero g, and can't just tilt it up to drink... the stuff would just sit in there, no gravity to pull it out.

Also, broken glass doesn't drop to the floor in space. It just floats around where people might breathe in small glass shards with bad results.

So any such fight would likely be just fists, as attacking someone with a plastic bag and straw won't accomplish much of anything... although you could add some comic relief by having one of your marines falling back on instinct and trying to smash their drink bag, before realizing how pointless that was and tossing it away.

Robyn had the best suggestion on how a fist fight might actually go, grab on and swing so you don't float away. Boxing rules get replaced by Newtonian rules, with actions and equal/opposite reactions.

Ironically, a space bar fight would likely end up being a fairly gentle affair, with people floating in all directions. Maybe it could end up with the two chief antagonists looking at each other and saying - this just isn't working.


I'm going to do a whole lot of speculation here.

Any bar in a zero-gravity environment would probably be stocked with materials that do not shatter or splinter, since those can hang in the air and cause lung problems. This means no glass and no wooden pool cues (possibly no pool cues at all, as that game needs gravity to work). By the same token, most if not all living spaces would be constructed to have a constant flow of air at all points to prevent particulate buildup, sending them over to a filtration system. The flow might be stronger here than elsewhere in the station to better handle vomit, but most of the time people will have barf bags within arms' reach.

Speaking of bodily waste, even in the future most people working in zero gravity would probably still be wearing diapers. For humans, the reflex that lets your body know that you need to use the restroom is very gravity-dependent, so you might not even realize you need to use it until it becomes an emergency. The actual evacuation processes for urine and feces, as well, normally depend on gravity. This has caused may problems for real-life engineers seeking to design toilets that work in zero gravity, and the ones we have now are still difficult to use. In this future scenario, we might have something more advanced that's more clean, comfortable, and reusable than current diapers, but in all likelihood it would still involve relieving yourself where you are. Bathrooms wouldn't need to be as common as they are on Earth as a result; they may even be limited to private quarters. In other words, our zero-gravity bar in space might not have an actual bathroom.

The process of drinking in zero-g would involve flexible straw-and-bag type containers that are unlikely to either spill or puncture. To prevent people from floating into inconvenient places, the stools would be anchored chairs or couches equipped with seat belts. The walls would be lined with handholds, and the furniture (if there is any) would be curved and rounded so nobody runs the risk of bashing their head on a sharp corner. They could serve food, as well, but it wouldn't be prepared in a way that could make lots of crumbs, and it would likely be prepared in a form that's easier for an inebriated patron to eat without making a mess.

There wouldn't likely be much furniture, aside from the seats. If you need to put your drink somewhere, you can just let go of it and it will stay put. No need for a table or counter top. If you have pool, it would need to be either virtual or embedded on a wall in the style of a pachinko machine. Darts would be unchanged, though they'd likely be blunted. The "bartender" would probably be a vending machine that mixes drinks by itself; if there is a human bartender, they might be separated from the customers with some type of cage enclosure. If this type of establishment expects patrons to get rowdy every so often, the cage setup is more likely.

So here we can visualize our bar. On all six walls there are various belted seats arranged such that groups of people can converse without much trouble. In one corner there's a cage where the bartender hooks bags together to mix their contents and tosses the resulting concoctions through the bars. The ventilation system is constantly whirring, and there's always a slight breeze that goes directly towards the nearest wall or floor (walls and floors are the same thing in zero gravity).

Our space marines are strapped in their seats in a big circle, or maybe they've set up a simple partition that keeps them from floating away when they aren't strapped in. They're sucking on bags full of whiskey or whatever liquor they drink in the future, and most of them are practically empty. The flattened, empty bags have slowly gravitated to the floor/wall, where suction keeps them from going anywhere else. They're chatting, they're laughing, they're having a good time.

In walks our cult. They float in, talk to the bartender, order drinks, and take seats once they've been served. After some time, they notice the space marines sitting on the adjacent wall, and they decide to start some trouble. The two groups exchange some obscene taunts. Other patrons can see where things are going, and they migrate away from both groups. Some people hurry up and leave. A couple of cultists pull knives that they made in their machine shop, then unstrap themselves and make their way over to the Marines' area. Usually they would climb the handholds like a ladder, but right now they're feeling brave (and inebriated) enough to just launch themselves straight towards the Marines in the hopes of getting in a cheap shot. One gets lucky and slams right into a Marine. The other fumbled his launch and landed on the wall nearby.

The first cultist aims his knife directly at the marine. He knows about momentum intuitively enough that he stabs from his center of mass to put his weight behind the strike and to prevent himself from spinning. The second cultist Thuds against the wall and drops his knife, which bounces and tumbles around the room.

The Marines are trained in hand-to-hand combat in zero gravity. A few maxims:

  1. Don't go looking for a fight, and if you can escape, do. It's usually easier to drift away from danger in space than on Earth.

This Marine has a cultist coming straight towards him with a bladed weapon. He can't avoid a fight. However, Newton's laws state that this cultist cannot change his speed or trajectory, and is effectively trapped. To give himself more freedom of action, he unstraps himself but keeps one leg in the strap.

  1. Anchor yourself before striking, and stay anchored. Fighting unanchored, your attacks will be weaker and you wont' be able to control where you drift.

The cultist has broken this rule. The Marine has no trouble using his enhanced reflexes to grab at the cultist's wrist, forcing them to drop the knife, and counterattack with a punch of his own.

  1. Maintain contact and disable your opponent. In other words, grab and grapple.

The Marine keeps a firm grip on the cultist, pulls him close, and starts wailing on him. Since he's anchored, he can throw the cultist at the wall without sending himself flying and follow up with more attacks.

  1. Stay anchored while grappling, and prevent your opponent from anchoring themselves.

The Marine, no matter what he does with the other three limbs, always keeps one foot in his strap or on a handhold. It's tricky to do, but he's trained for this. To keep the cultist from reaching a handhold, he uses throws to keep him off-balance.

  1. Go for the joints, just like on Earth.

Once the cultist is disoriented, the marine pulls him into a closer grapple, exerting control on the cultist's joints to keep him from mounting an effective counterattack.

The second cultist, now disarmed, reorients himself and realizes that one of the Marines is headed straight for him. The Marine uses his momentum to tear the cultist off of his handhold, then catches a handhold himself and uses it to launch his own barrage. However, the cultist gets a lucky kick in, sending the Marine flying. The Marine, however, keeps his grip and both of them go flying in the air.

  1. If you are drifting, you are vulnerable from five sides. Be especially aware of your surroundings when drifting.

At this point, the Marine can either pull the cultist close and punch continuously, or he can throw the cultist off and use the momentum to change his trajectory. Since he knows the cultist has allies, he kicks the cultist away and sends himself toward a wall where he can re-anchor himself.

At this point the rest of the cultists are joining the fight. Some of them have the sense to stick to handholds, but others are trying to use the flying tactic like the first one, too drunk to realize that it's a losing strategy.

Everything that follows is pure chaos. Some people get sent spinning into the center of the room, only to crash into an opposite wall. The Marines are outnumbered and unarmed. Their superior reflexes are dulled by the alcohol, but they're both stronger and more massive, meaning they can more effectively control momentum. Some of them have been able to take knives from the cultists. The fight is short and brutal; blood spatters every which-way, each droplet eventually getting sucked up into a wall. There is no reliable way to avoid getting stabbed in a knife fight, so some of the marines get cut up pretty badly, but the cultists unlucky enough to have their knives taken are cut up much worse. Some cultists cut and run, as do all the other patrons.

By the time station security gets there, people are on the walls and floating in midair, throwing punches and stabbing at each other. Some people floating are dead or unconscious; for them, blood is expanding outward from any open wounds they have into an amorphous blob. A big glob of bloody vomit is drifting lazily toward an opposite wall, splattering in slow motion onto it and then getting sucked up. One person is spinning uncontrollably in the middle of the room, unable to stop themselves.

  • $\begingroup$ The enemy's gate is Down. $\endgroup$ Dec 17, 2020 at 22:23

This is about fight dynamics aspects, on which I fear some people have misconceptions.

  • first of all, the effectiveness of punches as such will not be affected in 0g. How they are thrown is that you set a part of your body, like your arm, into a rapid motion. After that, gravity plays no role, the damage is delivered purely by inertia, which would be the same in zero g.
  • the momentum involved in, say, in a boxing punch, is relatively small. Your arm is about 5% of your body mass, so if you punch someone your mass, they will acquire 5% of the speed of the punch, so they will at best very slowly drift. When a boxer is knocked out, they fall because they black out, not because their body is set to fly.
  • Punching someone will not set you to fly in the opposite direction. Even of you throw not just an arm, but the whole body weight, after a perfectly elastic collision with an opponent of equal mass, they will be set to fly, and you will stop (think of billiard balls). In reality the collision will be inelastic, so you both will be moving together in the direction of the punch.
  • That said, some techniques of how you set your body parts to move may not work well, while others will still work perfectly. Most boxing punches are done by rotating the hips and the torso, and to create torque for that, you need friction on the ground. If you have two handles on a wall about 80cm apart, you can press your feet against them from inside, but never moving your feet makes for poor boxing. On the other hand, a certain famous headbutt is totally suitable for 0g: what Zidane does is basically, create a spring of his body and then unleash. All he needs is a wall behind him to press his foot against.
  • one large problem is that if you miss, you retain momentum and/or angular momentum, so that you may fly until you hit the other wall, or just spin. Which leads us to the main skill for a fight in 0g: flying and bouncing around! When you have just bounced off the wall, there are just two things you cannot change: momentum and angular momentum. But, you can still do a lot of things with your angular velocity and the action of rotation, by changing your body shape. You can train, like a cat, to always land on your paws, and bounce back in exactly right direction and velocity and with angular momentum you want. All that subliminal, of course - that's no different from many other things a human can learn to do without thinking.

Imagine yourself floating in the middle of the room when a 6-packed marine bounces off a wall and heads your way, rotating. as he approaches, he groups himself to start rotating very fast, like a figure skater, and as this spinning thing passes you, a limb sticks out to switch you off. Pretty spectacular, huh?

  • $\begingroup$ Just jumping in to comment on the punching comment: There are fighting techniques in which you lock your core and push off your leg into a punch to create a rigid or semi-rigid structure from fist to back foot. In this way, extra force generated by the muscles that would normally not land in the punch, would be backed up by the traction to the ground, and therefore more force can land. Outside of that, I agree, mostly, the existing intertia is good enough to land a good punch. $\endgroup$
    – Harry Mu
    Feb 18, 2023 at 23:52

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