Vast Body of Water Surrounds Distant Black Hole

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Vast Body of Water Surrounds Distant Black Hole

Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe. The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away.
 
It's the universe's largest plughole :D
 
But does the water drain clockwise or anti-clockwise...
 
adz said:
Vast Body of Water Surrounds Distant Black Hole

Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe. The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away.
Click to expand...

That makes my brain hurt.
 
Of course, when they say water, they doubtless mean an immense cloud of gas and dust that is rich in water molecules, rather than a big swirling mass of liquid water. Which would be even more awesome, though extraordinarily unlikely.

Hmmm. I wonder what mass of water would be required to collapse under gravity in order to give a differentiated body composed entirely of different phases of water?
 
Karlos said:
Hmmm. I wonder what mass of water would be required to collapse under gravity in order to give a differentiated body composed entirely of different phases of water?
Click to expand...
I often wonder the same thing.
 
motorollin said:
I often wonder the same thing.
Click to expand...

I suppose the simplest way to approach the problem is to work out what mass of water (with the simplifying assumption that it is wholly incompressible and at a uniform temperature) would be required to form a spherical drop with sufficient surface gravity to hold down a shell of gas (water vapour) that would be in equilibrium with the liquid surface at whatever temperature we are interested in. Obviously we want our "water world" to be wet, since you can already make ice balls any size you like, so perhaps the triple point might be a good surface temperature/pressure to conduct this thought experiment at.

Then consider the many known phases of ice: http://en.wikipedia.org/wiki/Ice#Phases

From that you can then factor in compression and estimate how such a body might collapse inwards giving a core of metallic water, wrapped in differentiated layers of various high pressure phases of ice and finally by your ocean / atmosphere.
 
Right, I think I have my first approximation for the perfectly spherical, homogeneous, incompressible sphere of water at the triple point - I've derived a function that equates mass into surface acceleration (g). It's not pretty. I'll use the caret (^) to signify raising to a power. First the preamble:

1. Density (should be symbol rho, but I can't be bothered to find it):
rho = m/v

2. Volume of a sphere:
v = 4/3 . pi . r^3

3. General equation for (magnitude) of force:
F = m.a

4. (Magnitude) of force between two masses at a distance r from their centres of mass:
F = G . m1 . m2 /r^2

5. Rearranging (1) for m and substituting (2) for v:
m = 4/3 . pi . rho . r^3

6. Rearranging (5) for r:
r = ( 3 . m / 4 . pi . rho)^1/3

7. Rearranging (3) for a and substituting (4) for F and letting m1 be the mass of the body of water (m) and m2 the mass upon which F is being calculated (note that m2 is cancelled out in the substitution):
a = G . m / r^2

8. Substitute (6) for r:
a = G . m / ( 3 . m / 4 . pi . rho) ^ 2/3

So, from (6) and (8) we can calculate the radius and surface acceleration due to gravity of our hypothetical planetary blob of water, given that G and pi are constant and rho is too when our water is magically incompressible and not given to changing phase under inordinate pressure.

Ideally, rearrange (8) to get m as a function of a and you can simply throw in whatever surface acceleration you want and get the mass required, but just playing around with these (plugging 999.84 kg/m^3 for rho at the triple point, 6.67384x10^-11 m^3 kg^-1 s^-2 for G), I get that a 100,000km diameter blob of water under these conditions would mass 5.2352x10^26kg and exert a surface acceleration due to gravity of 13.98 m/s^2.

Way more than enough to hold down the measly 611.71 Pa partial pressure of water vapour at the triple point :)
 
^ in light of which, I call first dibs on the total water content in Oort cloud if the species goes through a technological singularity and onto a post physical footing before I die...
 
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@Karlos
For your efforts I award you 10, count 'em 10, Internets :banana:
 
Well, if oddball ideas like this amuse you, try this one.

You have a blob of pure "neutronium", (neutron degenerate) matter composed entirely of neutrons left over from some stellar event (of course it would never be pure, but this is a theoretical exercise). If a wandering interstellar proton were to hit it, does it become a single atom of a super-heavy isotope of hydrogen for a brief instant?
 
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