How would a spirit level function in space?

I am assuming that by "in space" you mean zero gravity and not in a hard vacuum.

I think that because water still has surface tension the bubble would not break up, but in zero gravity the term top really has no meaning. In my opinion the bubble would just float randomly in the vial.

Yes I do mean zero gravity. I realize that top doesn't become an important reference

but the true reference in a level is the vial to the edge of the level. If by floating randomly you mean it is not in contact with the inside surface of the vial that is fine because if the bubble was obeying any laws of consistency then the vial would still act as a reference to the edge of the level. Does zero gravity negate the self referential quality of a level?

I'm not sure what the 'self referential quality' is that you refer to.

I think the bubble would move to one end of the chamber to minimise surface area and the bubble/liquid interface would be spherical with the radius determined by surface tension.

is there ever reallyany substantial volume of space where there is zero gravity?

No.

It would not work as a level, as a fluid will not form a level in zero gravity.

In zero gravity it will be governed by inertia and surface tension.

It can still evaporate, if water. It can be boiled but the steam pressure will force it from the heating surface by reaction alone.

drops will float and coalesce into a sphere as they contact. They will also blot into clothing under the capillary action, etc.

Fluids are a real problem in space and speacial zero0 void tanks have to be created to deal with them it you need a flooded inlet on a pump. Often they have a small solid rockert that fires to settle fuel.??

If you make a large enough spirit level and put it in orbit, it will work, but instead of showing the horizontal level it will show the vertical, i.e., the bubble will go to the center when the line through the two ends of the tube is vertical.

The reason for this "bizarre" behaviour is tidal gravity (also called-micro gravity in orbits). I happens because orbiting objects follow the orbit of their center of mass (COM). Below the centre of mass, Earth's pull is slightly stronger than at the COM and the pressure in the fluid is higher there than at the COM. Above the COM, the gravity is slightly weaker than at the COM and the centrifugal force causes the pressure in the fluid to be higher there as well.

The air bubble will float the the point of lowest pressure, i.e., on the COM. The reason why a large spirit level would be required is because the micro-gravity is really small, about 0.2 μg per meter. If you want to know more about micro-gravity, visit Relativity 4 Engineers and read the pdf download from the page: Tidal Gravity.

Regards, Jorrie

Quite.

The wisdom and economics of placing a large-enough spirit level into space then need to be called into question!

It could also fuction as a solid state, (rock and a stick), indicator of the
direction of any accelleration applied.
(Similar to the 'needle & ball` instrument still required in aircraft even if
a gyro horizon is installed.)

Hi Pragmatist,

"Similar to the 'needle & ball` instrument still required in aircraft even if
a gyro horizon is installed."

You may find it interesting to know that the needle part to the bank and turn indicator (bat and ball) is actually a gyroscope that is aligned vertically and it is also used as a backup instrument for the artificial horizon. Part of your primary instrument training (or at least mine was) requires you to fly using the bank and turn indicator as a substitute for the artificial horizon.

They are also normally powered from two separate sources. For example if the artificial horizon is powered electrically the bank and turn indicator is vacuum powered.

What about the air bubble spreading evenly over the glass surface (so, for the eye) actually disappearing?

...air bubble spreading evenly...

This would depend on the viscosity and surface-tension of the said fluid, wouldn't it?

Where in space is zero gravity found?

There seems to be two situations to be considered.

1 a stationary (to what) person in deep space.

2 a person in orbit experiencing zero gravity.

Will Jorrie's bubble behave the same in both situations?

2 can be tested quite easily by free falling and observing. (a parachute or bungee rope is essential)

Hi Hendrik.

In deep space the bubble would not know where to go, because the gravity effect, especially tidal gravity, will be negligible.

I prefer to refer to orbital conditions as micro-gravity, not zero gravity, as argued before.

To be tested by a parachutist will be tricky, because as soon as any airspeed builds up, the fall is no longer an "inertial free fall" and the spirit level will behave normally. Orbit is the only practical option, I think.

Regards, Jorrie

Hi Jorrie

Yes i can see now that the bubble will show the vertical.

What will happen if the level is rotated (lengthwise) 90deg or 180deg once the bubble has settled?

I have interesting proof that a spirit level can be influenced. I will find the information and post it.

Hi Hendrik, you wrote: "What will happen if the level is rotated (lengthwise) 90deg or 180deg once the bubble has settled? "

I have no idea, because the tidal gravity over the "horizontal" spirit level will be extremely tiny. If one ignore surface tension and sticking, I guess the bubble would hypothetically divide into two and each half will go to the level of the centre of mass of the spirit level on opposite sides.

Regards, Jorrie

If I remember correctly gravity is the based on the mass of an object which means even if a place of true zero g's exist and you were to place the spirit level there, the level would form it's own gravity well, a very weak one but still.... And for the sake of simplification friction and viscosity are being ignored.

a common spirit level such as this one (just the ampule not the frame) is curved thus putting it's center of gravity towards the center of the shorter radius. The fluid having a higher specific gravity would displace the air bubble to the center point of the Long radius. Of course the center of gravity is also dependent on the starting point of the bubble so you have three possible places for the bubble to end up, end #1 , centered as seen above or at end #2, take your pick.

Am I near the ballpark Jorrie?

The bubble will form a sphere, and if you have a 10 pound mass for gravity you might have a ~trillion trillionth of a g making it float upgee, so if you are prepared for a ~100 year settling period and add some more for bounce, it might work?

Why?

To have everything level and organized in space.

What will it look like with every structure placed at random?

How would you know which side of a black hole is the top?

Yes you are correct. WHY?

In the absence of gravity, surface tension would be the overriding force. My guess is that the bubble would go to one end of the tube and stay there if the amount of surface exposed would be minimum.

I'm going to argue with myself, having thought about it a little bit. If the liquid sticks to the glass more than to itself (meniscus going up, not down - in gravity), then I think the liquid forces would push the bubble to the middle.

I doubt that we can get NASA to test this for us. Maybe dropping in off the house and looking really quick...

After reading both of your posts I am not sure which one is correct. I think a lot depends on the interior surface of the vial and the liquid used. If the liquid is plain water and the surface is like a freshly waxed car then it seems the bubble would have the greater attraction to the surface. If some sort of surfactant was used (soap) then it seems the liquid would have the greater attraction to the surface. I need to think about this a little longer to get my brain wrapped around it.

In Orbit with centrifugal force and variable gravity affects it might do something but it would take a lot of programming and testing to tell you what it means. In non-gravitational and zero acceleration or any other force, it will tell you nothing. In that case a gyro is your only bet unelss you have an optical sensored computer judge your relative position in mapped star field and thus your vessel attitude relative to youe expected direction. Otherwise just put a grid verticle and horizontal lines in the craft so you hang youe pictures straight without a level.

Well, if the spirit level does not work in space, how are we going to get our snooker table levelled out there? This really could spoil the fun!

table N pole, balls all S pole(with a small hollow space inside N,,,can that be done?). The extra force required to make them hit(cue ball also N) adds to the requisite skill. Else make them inside a cube with a constant mag field and the balls non magnetic, but conducting so they are slowed by the field as shorted turns.

Other ideas?

Hi aurizon,

Wouldn't it be easier if you just made the table magnetic and use a ferrous material for the balls. That way the balls would stick to the table but not try and avoid each other.

Hi Masu! I like the idea of 3 dimensional weightless snooker, for extra difficulty.

Now that could be an interesting game. A cube that was the size of a billiard table with a pocket in each corner and the center of each edge, 20 in all. You then have to pot the balls the same way as you do in snooker using a cue and white ball.

I am just trying to figure out how to increase the friction enough that the balls will stop moving within a reasonable time frame. Perhaps if the balls were table tennis balls rather than billiard balls. They would be similarly elastic and the friction with the air would slow them down to a dead stop fairly quickly. You would need to be careful though as a player moving about the playing room could easily cause disturbances in the air that would upset the balls.

I have a better ides of a way to do it on Earth rather than in orbit. You could do it if the room was filled with water and the balls had exactly the same density as the water thus canceling out the gravity. The only problem with this idea is that it would be difficult for the players to breath. It would need some sort of remote control cue that could be used from outside.

Has anybody got any ideas?

copper balls in a uniform mag field would experience drag on flight and rotation that would bring them to a halt. The trouble is the left hand rule will curve their path if you have any intrinsic magnetism due to the induced currents. I am nor sure of there is any way to make a drag friction analog. A very viscous gas might work, but then the players need masks. I wonder if there is a very viscous gas that would work here? The nature of gasses tends to make them very low in viscosity. Possibly heavy halide hydrocarbon refrigerant gas??

I wanted some avoidance as both the cue and object ball would skitter in a learnable manner. You could even make a noncontact pot by repulsion alone. With strong enough magnets contact would occur less, or never. With a copper coated orin tablke you would get rolling 'friction', so balls would come to a stop.

Now, lets try table tennis. Velcro shoes/floor. With no fall, the serve would need to be a toss down bounce with a hand serve. Have to be a limit there to avoid smash serves. Possibly a standard serving machine to serve with a few presets. Serve would be from air to table, + bounce and the returns start from there to land on the table.

Might be a game in there?

The whole thing can be done in NASA's Vomit comet the one that does the free fall from 35,000 feet. But in true space the whole idea of using a normal spirit level is a waste of time because you could never put it down and see the bubble at the same time. Laser sighting is used fore real, over the short distances that involved it is the cheapest and quickest method.

Spell checker oh no not again!

"The whole thing can be done in NASA's Vomit comet the one that does the free fall from 35,000 feet."

Actually that is a bit of a misconception about how the vomit comet actually achieves zero G. It actually follows a flight path like this

While the aircraft is in the red part of the flight path you experience about 2 G and while in the green parts you experience 0 G. Basically the green section are the parabolic path a projectile would follow if in free flight hence the weightlessness. The red sections are the same shape but since they are an inverted parabola you experience 2 G .

Hi Masu, I suppose the "Vomit Comet" makes it a bit easier on everyone by changing smoothly from 0g to +2g. I know it can be done virtually instantly, but that's rather nasty, especially if you're not securely on the floor!

Regards, Jorrie

...it can be done virtually instantly...

Sure, Einstein's Elevator: A free-fall into a "seemingly" zero G, it's just the eventual meeting with earth that's nasty, the rest is pure fun...

Yes I did know what you so pedanticaly explain.

My apologies BrainWave, your statement;

"NASA's Vomit comet the one that does the free fall from 35,000 feet"

seemed to indicate otherwise.

My guess is that the spirit level will destroy itself.

In the vacuum of space, the air pocket in the tube will exert pressure on the walls of the tube and burst it, freeing its spirit and sending it out into the vastness of space. Now the instrument becomes an empty piece of metal that can be used to repair the International Space Station .

In space bubble and the sprit have no weight; hence specific gravity has no meaning.

This amounts in saying that they have same relative density.

If this is agreed, how about an analogy on earth for a comparable situation:

In a container take a solution (whose specific gravity can be manipulated) and granules with same specific gravity.

Now let us analyze what happen to these granules, float, suspend, settle or bit of all…

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