Question on really deep oceans

[Sea Wasp (Ryk E. Spoor)]

According to my examination of the phase tables for water, in an ocean
under ~1g and in the 300k or so range, a little more than 60 miles down
it will turn into Ice VI, and deeper (250 miles?) to Ice VII.

Both of these exhibit Debye Relaxation, according to wiki and other
sources.

Are there any interesting implications of this with respect to the
phenomena to be expected on such a planet? I'm not talking about what a
Debye Relaxation-prone material can do in lab circumstances but about
large masses in a real-world environment, possibly covered to some depth
on top with accumulated sediments (possibly, depending on circumstances,
compacted to rock of some sort) and far down resting on bedrock or the
equivalent of mantle material (turning to supercritical fluid if it's
overheated, of course).

--
Sea Wasp
/^\
;;;
Website: http://www.grandcentralarena.com Blog:
http://seawasp.livejournal.com

[alie...@gmail.com]

On Sep 23, 6:09 am, "Sea Wasp (Ryk E. Spoor)"

<seaw...@sgeinc.invalid.com> wrote:
>         According to my examination of the phase tables for water, in an ocean
> under ~1g and in the 300k or so range, a little more than 60 miles down
> it will turn into Ice VI, and deeper (250 miles?) to Ice VII.

M'kay.

>         Both of these exhibit Debye Relaxation, according to wiki and other
> sources.

M'kay.

>         Are there any interesting implications of this with respect to the
> phenomena to be expected on such a planet? I'm not talking about what a
> Debye Relaxation-prone material can do in lab circumstances but about
> large masses in a real-world environment, possibly covered to some depth
> on top with accumulated sediments (possibly, depending on circumstances,
> compacted to rock of some sort) and far down resting on bedrock or the
> equivalent of mantle material (turning to supercritical fluid if it's
> overheated, of course).

(Refreshing organic memory via Wikipedia)

"Debye relaxation is the dielectric relaxation response of an ideal,
noninteracting population of dipoles to an alternating external
electric field."

Yeah, that's what I thought.

Bwuh? Will this hypothetical deep-ocean world have a core that
radiates high-power microwaves?


Mark L. Fergerson

[Moriarty]

On Sep 23, 11:09 pm, "Sea Wasp (Ryk E. Spoor)"

<seaw...@sgeinc.invalid.com> wrote:
>         According to my examination of the phase tables for water, in an ocean
> under ~1g and in the 300k or so range, a little more than 60 miles down
> it will turn into Ice VI, and deeper (250 miles?) to Ice VII.
>
>         Both of these exhibit Debye Relaxation, according to wiki and other
> sources.
>
>         Are there any interesting implications of this with respect to the
> phenomena to be expected on such a planet? I'm not talking about what a
> Debye Relaxation-prone material can do in lab circumstances but about
> large masses in a real-world environment, possibly covered to some depth
> on top with accumulated sediments (possibly, depending on circumstances,
> compacted to rock of some sort) and far down resting on bedrock or the
> equivalent of mantle material (turning to supercritical fluid if it's
> overheated, of course).

ObSF time: Iain M Banks' _Surface Detail_ has a trip down to the
depths of an iceworld's ocean. Although I'm not an expert, he seemed
to get the physics right.

But I can't for the life of me remember if I've seen that elsewhere in
SF. Any others? I'm guessing that, given Wasp's interest in the
topic, in a year or two there might be a new Spoor work where we see
it.

-Moriarty

[Charles Bishop]

In article <k3n1m3$ri9$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)"

<sea...@sgeinc.invalid.com> wrote:

> According to my examination of the phase tables for water, in an ocean
>under ~1g and in the 300k or so range, a little more than 60 miles down
>it will turn into Ice VI, and deeper (250 miles?) to Ice VII.
>
> Both of these exhibit Debye Relaxation, according to wiki and other
>sources.
>
> Are there any interesting implications of this with respect to the
>phenomena to be expected on such a planet? I'm not talking about what a
>Debye Relaxation-prone material can do in lab circumstances but about
>large masses in a real-world environment, possibly covered to some depth
>on top with accumulated sediments (possibly, depending on circumstances,
>compacted to rock of some sort) and far down resting on bedrock or the
>equivalent of mantle material (turning to supercritical fluid if it's
>overheated, of course).

Not to derail the original question, but I have a sub-question. Is it
possible to have a earth type world (liquid water, &c.) that can have a
250 mile deep ocean, or a 60 mile deep one? That is, that deep in places,
much the same that the Marianas trench is a deep part of the Pacific
Ocean.

I just wondered if gravity "allows" such depths on an earth type world
without filling them them in, over time, of course, smoothing the bumps
and holes in the surface in a world big enough to have them to begin with.

--
charles

[Sea Wasp (Ryk E. Spoor)]

On 9/25/12 2:31 PM, Charles Bishop wrote:
> In article <k3n1m3$ri9$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)"
> <sea...@sgeinc.invalid.com> wrote:
>
>> According to my examination of the phase tables for water, in an ocean
>> under ~1g and in the 300k or so range, a little more than 60 miles down
>> it will turn into Ice VI, and deeper (250 miles?) to Ice VII.
>>
>> Both of these exhibit Debye Relaxation, according to wiki and other
>> sources.
>>
>> Are there any interesting implications of this with respect to the
>> phenomena to be expected on such a planet? I'm not talking about what a
>> Debye Relaxation-prone material can do in lab circumstances but about
>> large masses in a real-world environment, possibly covered to some depth
>> on top with accumulated sediments (possibly, depending on circumstances,
>> compacted to rock of some sort) and far down resting on bedrock or the
>> equivalent of mantle material (turning to supercritical fluid if it's
>> overheated, of course).
>
> Not to derail the original question, but I have a sub-question. Is it
> possible to have a earth type world (liquid water, &c.) that can have a
> 250 mile deep ocean, or a 60 mile deep one? That is, that deep in places,
> much the same that the Marianas trench is a deep part of the Pacific
> Ocean.
>

Well, depends on how Earthlike. You're not going to get continents with
dry land and oceans that are a hundred miles deep; the continents will
sink down because they represent WAY too much mass to be supported
(continents may seem solid to us, but they're really just thin crusts
floating on plastic, near-liquid mantle and thus if they get too thick,
they sink down).

You can certainly get a world with liquid water that has great depth --
many miles. But (assuming roughly earth-normal gravity) at about 60
miles or so, at temperatures around what we consider normal, it'll start
to turn to Ice VI, later to Ice VII and possibly others depending on
temperature and exact pressure and so on. (see a phase diagram of water
for exact numbers and such)

[Wayne Throop]

: "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com>

: Well, depends on how Earthlike. You're not going to get continents

: with dry land and oceans that are a hundred miles deep; the continents
: will sink down because they represent WAY too much mass to be
: supported (continents may seem solid to us, but they're really just
: thin crusts floating on plastic, near-liquid mantle and thus if they
: get too thick, they sink down).

Well... they are also composed of light fluffy rocks, not so dense
as the bassalt plates underneath. Otherwise, they'd be too heavy
to even poke up out of earth's puny oceans. But yes, also, even
with light fluffy rock, you're not going to get it peeking out of
60km of water.

"Also cute and FLUFFY!" --- Stitch to Gantu

"The learned gentlemen from the university have asked me if I relied
on Einstein's General Theory of Relativity or if I used the simpler
rules of Newton's Law of Universal Gravitation on the evening in
question when I accidentally took Sheriff Johnson's life. Shit.
I don't know. I just got angry and squished the fucker. But I've
gotten better at running things and I promise not to do it no more."

--- Jake "Heavy" Sullivan
Parole Hearing, Rockville State Penitentiary, 1928
(he squished the sheriff, but he didn't squish the deputy)

Sullivan took every bit of Power he had and let it go all at once,
increasing gravity's strength, bellowing at the world to pull them
down under the strength of 50 earths. [...] The foundations cracked
and turned to powder under the pressure [...] Rokusaburo was just
gone, replace by a sudden pressurized red mist that instantly
coated the entire basement.

--- Jake "Heavy" Sullivan, running things better after his parole
(Rokusaburo was an Iron Guard, not technically a sheriff...)
(plus, it was a clear-cut case of self-defense)
(Rokusaburo was one baaaaad mother(shut your mouth)
so he was dropped down a ... ahem... shaft)

[JRStern]

On Tue, 25 Sep 2012 14:10:17 -0400, "Sea Wasp (Ryk E. Spoor)"

What is the normal temperature, on Earth, at 60 miles?

J.

[Wayne Throop]

:: You can certainly get a world with liquid water that has great depth

:: -- many miles. But (assuming roughly earth-normal gravity) at about
:: 60 miles or so, at temperatures around what we consider normal, it'll
:: start to turn to Ice VI, later to Ice VII and possibly others
:: depending on temperature and exact pressure and so on. (see a phase
:: diagram of water for exact numbers and such)

: JRStern <JRS...@foobar.invalid>
: What is the normal temperature, on Earth, at 60 miles?

I note that since water convects much faster than rock,
comparing temperatures 60 km depth in rock to 60 km depth in water
is quite like comparing apples to bicycles.

[William December Starr]

In article <13485...@sheol.org>,

thr...@sheol.org (Wayne Throop) said:

> "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com>
>

>> You're not going to get continents with dry land and oceans that
>> are a hundred miles deep; the continents will sink down because
>> they represent WAY too much mass to be supported (continents may
>> seem solid to us, but they're really just thin crusts floating on
>> plastic, near-liquid mantle and thus if they get too thick, they
>> sink down).
>
> Well... they are also composed of light fluffy rocks, not so dense
> as the bassalt plates underneath. Otherwise, they'd be too heavy
> to even poke up out of earth's puny oceans. But yes, also, even
> with light fluffy rock, you're not going to get it peeking out of
> 60km of water.

But if you ever do, at least we know from Larry Niven what you're
supposed to shout in surprise.

-- wds

[Michael Stemper]

In article <k3ss2a$27g$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com> writes:
>On 9/25/12 2:31 PM, Charles Bishop wrote:

>> Not to derail the original question, but I have a sub-question. Is it
>> possible to have a earth type world (liquid water, &c.) that can have a
>> 250 mile deep ocean, or a 60 mile deep one? That is, that deep in places,
>> much the same that the Marianas trench is a deep part of the Pacific
>> Ocean.

> You can certainly get a world with liquid water that has great depth --
>many miles. But (assuming roughly earth-normal gravity) at about 60
>miles or so, at temperatures around what we consider normal, it'll start
>to turn to Ice VI, later to Ice VII and possibly others depending on
>temperature and exact pressure and so on. (see a phase diagram of water
>for exact numbers and such)

So, Nevia, as described, is right out?

--
Michael F. Stemper
#include <Standard_Disclaimer>
Life's too important to take seriously.

[Sea Wasp (Ryk E. Spoor)]

I'm not sure what the actual depth of Nevia's oceans was, since I don't
have _Triplanetary_ to hand. A depth of 20 miles with a few scattered
islands peeking out would be feasible. more than that, probably not. I
could imagine some mechanisms to provide very occasional super-high
mountains, but they wouldn't last for even human timescales, let alone
geologic.

[Wayne Throop]

: "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com>

: I'm not sure what the actual depth of Nevia's oceans was, since I

: don't have _Triplanetary_ to hand. A depth of 20 miles with a few
: scattered islands peeking out would be feasible. more than that,
: probably not. I could imagine some mechanisms to provide very
: occasional super-high mountains, but they wouldn't last for even human
: timescales, let alone geologic.

The islands could be dynamically supported by mantle plumes.
Or the tectonics could be otherwise very non-earthlike.

[Andrew Plotkin]

Floating islands.

Not that I have any idea how to produce *them* on a deep-ocean world.
I guess you start by figuring out a plausible mechanism for a
twenty-mile-high convection cycle -- get minerals and nutrients up
from the sea-floor to the lighted zone -- and then invent big, big
algae. Let floating seaweed mat up and "petrify", or dry out anyhow.
Maybe a population of microorganisms that like to cling to the roots
and bubble.

--Z

--
"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."
*

[Wayne Throop]

::: A depth of 20 miles with a few scattered islands peeking out would

::: be feasible. more than that, probably not. I could imagine some
::: mechanisms to provide very occasional super-high mountains, but they
::: wouldn't last for even human timescales, let alone geologic.

:: The islands could be dynamically supported by mantle plumes.
:: Or the tectonics could be otherwise very non-earthlike.

: Andrew Plotkin <erky...@eblong.com>
: Floating islands.

Oooh, cool.

: Not that I have any idea how to produce *them* on a deep-ocean world.

: I guess you start by figuring out a plausible mechanism for a
: twenty-mile-high convection cycle -- get minerals and nutrients up
: from the sea-floor to the lighted zone -- and then invent big, big
: algae. Let floating seaweed mat up and "petrify", or dry out anyhow.
: Maybe a population of microorganisms that like to cling to the roots
: and bubble.

Giant turtles. Xref "Mysteries of the Arcana" (where it's turtles all the
way down, http://mysteriesofthearcana.com/index.php?action=comics&cid=231
And also xref The Last Airbender, and the giant lion-turtle therein.
And David Duncan's "West of January", where all the cities are built on
turtles.

[Sea Wasp (Ryk E. Spoor)]

On 9/26/12 1:40 PM, Andrew Plotkin wrote:
> In rec.arts.sf.written, Wayne Throop <thr...@sheol.org> wrote:
>> : "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com>
>> : I'm not sure what the actual depth of Nevia's oceans was, since I
>> : don't have _Triplanetary_ to hand. A depth of 20 miles with a few
>> : scattered islands peeking out would be feasible. more than that,
>> : probably not. I could imagine some mechanisms to provide very
>> : occasional super-high mountains, but they wouldn't last for even human
>> : timescales, let alone geologic.
>>
>> The islands could be dynamically supported by mantle plumes.
>> Or the tectonics could be otherwise very non-earthlike.
>
> Floating islands.
>

That's not a problem. I've already designed THAT part of the world,
named the creatures involved, figured out where they fit in the cycle,
all that kind of stuff.

[alie...@gmail.com]

On Sep 26, 11:06 am, "Sea Wasp (Ryk E. Spoor)"

<seaw...@sgeinc.invalid.com> wrote:
> On 9/26/12 1:40 PM, Andrew Plotkin wrote:
>

> > In rec.arts.sf.written, Wayne Throop <thro...@sheol.org> wrote:
> >> : "Sea Wasp (Ryk E. Spoor)" <seaw...@sgeinc.invalid.com>

> >> : I'm not sure what the actual depth of Nevia's oceans was, since I
> >> : don't have _Triplanetary_ to hand.  A depth of 20 miles with a few
> >> : scattered islands peeking out would be feasible.  more than that,
> >> : probably not.  I could imagine some mechanisms to provide very
> >> : occasional super-high mountains, but they wouldn't last for even human
> >> : timescales, let alone geologic.
>
> >> The islands could be dynamically supported by mantle plumes.
> >> Or the tectonics could be otherwise very non-earthlike.
>
> > Floating islands.
>
>         That's not a problem. I've already designed THAT part of the world,
> named the creatures involved, figured out where they fit in the cycle,
> all that kind of stuff.

OK, so why are you concerned with the high-frequency dielectric
properties of exotic benthic ices? Is there an enormously powerful RF
source down deep, or am I asking for a spoiler?


Mark L. Fergerson

[John F. Eldredge]

Pumice, plus some plant that tends to grow in a network around
collections of pumice? You would get a fairly flat island, but it would
float.

--
John F. Eldredge -- jo...@jfeldredge.com
"Reserve your right to think, for even to think wrongly
is better than not to think at all." -- Hypatia of Alexandria

[Sea Wasp (Ryk E. Spoor)]

Looking for cool stuff to exploit -- will natural processes cause it to
build up charge and electrocute everything above it? Will it transmit
radio waves naturally? I have no idea what the stuff does, but since the
characteristic of the ice was mentioned in my references I figured I'd
ask to see if there were some likely (or not so likely but believable)
consequences of those ices' characteristics.

[Jens Kleimann]

What about icebergs, or large chunks of sea ice? Floating by definition, the (potentital) problem being that they don't last all that long. Or permanently frozen polar caps. Whould these count? And, more interestingly, whould a floating ice cap on an all-water planet stay at the pole despite it not being connected to solid bedrock below?

Jens.

--
Remove '_nospam' for actual email address.

[JRStern]

On Tue, 25 Sep 2012 20:28:25 GMT, thr...@sheol.org (Wayne Throop)
wrote:

Yeah but you've got to start somewhere.

SW said "at temperatures around what we consider normal", I suppose
meaning 25c. Problem is that at first approximation, temperature on
Earth in the mantle goes up about 25c per kilometer, per
Google/Wikipedia. Giving us roughly 2500c 60 miles down. May impact
his Ice VI scenario.

OTOH, following your lead, the entire planet may cool much faster with
that much water. OTOOH, if Ice XXX does manage to form, it won't be
convecting much faster than stone. Or will it?

Then there's this:

http://www.nationalgeographic.com/explorers/bios/kevin-hand/

“Europa is about the size of our own moon,” Hand explains. “Its vast
ocean is likely more than 60 miles deep (Earth’s ocean depths reach
only about seven miles). That means Europa may harbor two to three
times the volume of all liquid water on Earth.”

--

Bottom line is that basically, I think SW can have just about as much
Ice VI as he needs for his plot. You could adjust the radioactives,
move the planet's orbit or adjust the star as necessary until everyone
was bored on the technibabble and went on with the story, or maybe
geoengineeer it, or add the rare element freezeronium.

Anyway we all know it's Ice IX we gotta watch out for.

J.

[JRStern]

On Wed, 26 Sep 2012 23:58:33 -0400, "Sea Wasp (Ryk E. Spoor)"
<sea...@sgeinc.invalid.com> wrote:

> Looking for cool stuff to exploit -- will natural processes cause it to
>build up charge and electrocute everything above it? Will it transmit
>radio waves naturally? I have no idea what the stuff does, but since the
>characteristic of the ice was mentioned in my references I figured I'd
>ask to see if there were some likely (or not so likely but believable)
>consequences of those ices' characteristics.

When caught up in a abc field, it will do xyz.

It will sink a type VI or VII cruise ship that hits the planet.

Maybe the Debye Relaxation make it especially good to cool mixed
drinks, or at least a ruthless corporation might claim so and mine the
planet hollow selling the cubes across the galaxy.

J.

[Sea Wasp (Ryk E. Spoor)]

I'm writing a putatively hard SF novel here, with one single known
violation of our laws of physics (the drive I'm using to get people
there); in a sense I'm trying to write a Hal Clement novel for the
2010s. So I don't want anything that a scientist who knows the field
will immediately just throw the book across the room for. Say "Okay, but
even if theory says that, no way would it ever actually WORK that way",
I'm fine with that. I just want to try to avoid as many complete
screwups as I can, while not missing out on potentially cool opportunities.

[Sea Wasp (Ryk E. Spoor)]

On 9/27/12 10:44 AM, JRStern wrote:
> On Tue, 25 Sep 2012 20:28:25 GMT, thr...@sheol.org (Wayne Throop)
> wrote:
>
>> :: You can certainly get a world with liquid water that has great depth
>> :: -- many miles. But (assuming roughly earth-normal gravity) at about
>> :: 60 miles or so, at temperatures around what we consider normal, it'll
>> :: start to turn to Ice VI, later to Ice VII and possibly others
>> :: depending on temperature and exact pressure and so on. (see a phase
>> :: diagram of water for exact numbers and such)
>>
>> : JRStern <JRS...@foobar.invalid>
>> : What is the normal temperature, on Earth, at 60 miles?
>>
>> I note that since water convects much faster than rock,
>> comparing temperatures 60 km depth in rock to 60 km depth in water
>> is quite like comparing apples to bicycles.
>
> Yeah but you've got to start somewhere.
>
> SW said "at temperatures around what we consider normal", I suppose
> meaning 25c. Problem is that at first approximation, temperature on
> Earth in the mantle goes up about 25c per kilometer, per
> Google/Wikipedia. Giving us roughly 2500c 60 miles down. May impact
> his Ice VI scenario.

But in the oceans, it gets COLDER the lower you go. To a minimum of
slightly above freezing for the particular concentration of salt. I.e.,
if you go down a kilometer in the Earth your temperature goes up by 25c,
if you go down a kilometer in the ocean you may find your temperature
goes DOWN by 25c. Cold water sinks... but ice floats, usually. The
density of Ice VI is greater than that of standard water; not sure if
it's greater than that of water at that depth. Have to check. Water
doesn't compress MUCH, but it will compress.

>
> OTOH, following your lead, the entire planet may cool much faster with
> that much water. OTOOH, if Ice XXX does manage to form, it won't be
> convecting much faster than stone. Or will it?
>
> Then there's this:
>
> http://www.nationalgeographic.com/explorers/bios/kevin-hand/
>
> “Europa is about the size of our own moon,” Hand explains. “Its vast
> ocean is likely more than 60 miles deep (Earth’s ocean depths reach
> only about seven miles). That means Europa may harbor two to three
> times the volume of all liquid water on Earth.”

That's because Europa has roughly 1/8th Earth Normal gravity, so the
pressure at the bottom of that ocean will only be roughly that of an
Earthly ocean 5 miles deep or so -- which being a little over 26,000
feet is considerably less than the deepest our oceans actually get here
(36,000 feet or nearly two miles deeper).

>
> Anyway we all know it's Ice IX we gotta watch out for.

There actually IS an Ice IX, but it doesn't, fortunately, have the
characteristics of the Ice IX mentioned by Vonnegut.

[Michael Stemper]

I wouldn't think there'd be a problem. One of our polar ice caps is not
connected to solid bedrock below, but it seems to stay in place.

[alie...@gmail.com]

On Sep 26, 8:58 pm, "Sea Wasp (Ryk E. Spoor)"
<seaw...@sgeinc.invalid.com> wrote:

> On 9/26/12 10:45 PM, n...@bid.nes wrote:
>
> >    OK, so why are you concerned with the high-frequency dielectric
> > properties of exotic benthic ices?
>
>         Looking for cool stuff to exploit -- will natural processes cause it to
> build up charge and electrocute everything above it? Will it transmit
> radio waves naturally? I have no idea what the stuff does, but since the
> characteristic of the ice was mentioned in my references I figured I'd
> ask to see if there were some likely (or not so likely but believable)
> consequences of those ices' characteristics.

I got nothing for Debye relaxation, but did you know that water ices
are proton conductors and can be magnetized?

From this paper:

http://physics.nd.edu/assets/29206/gower_christina_monte_carlo_simulation.pdf

"Ice VI and Ice VII are known as the self-clathrate forms because
their structure is composed of interpenetrating lattices with
tetrahedral bonds." (No other ices have this characteristic.)

and goes on to discuss modeling their magnetizability.

Suppose there's sufficient irregularly-distributed stuff [element,
compound, whatever] on your world to dope benthic ice at a particular
stage in transition between VI and VII so that it becomes strongly
ferromagnetic (maybe by linking the disordered separate latices so all
the proton spins can align?), strongly enough to produce a noticeable
(/usable) field wherever your drama occurs; surface or the deeps. You
would probably get multiple magnetic poles. It occurs to me that
quakes would strongly alter the magnetic field by moving the critical
pressure up or down (or sideways) through ices with the proper dopant
concentration, making navigation more "interesting" for all involved.
You could get auroras at all latitudes, moving with the field
changes...

What to use as a dopant? I don't know. Doc Smith got away with
claiming that a little Rhenium made a super-strong alloy (Leybyrdite)
at least partly because nobody could gather enough Rhenium to call BS
on him. Pick something fairly exotic.

Oh, look:

http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust

No wonder Doc used Rhenium. ;>)


Mark L. Fergerson

[Sea Wasp (Ryk E. Spoor)]

Actually, one of his favorites was an osmium-iridium alloy -- both of
them even farther down the charts!

[Aleksandar Kuktin]

Hello group!

But, if I remember my geography right, the arctic ice cap is conected to
the continents on it's side.

I believe a polar ice cap on an all-water planet would stay on the pole,
provided there are no sudden movements equatorwise. The ice that composes
said cap, however, would not stay on the pole.

The polar ice cap would be in a steady state with reguard to the
surrounding ocean. If it is moving in a certain direction, the ice on the
leading edge would melt, but it would be replaced by newly forming ice on
the trailing edge of the ice cap. A section of the ice cap, however would
eventualy melt as it moves from the trailing edge to the leading edge.
Any city build on this section of ice would also eventually sink.

In the event of a sudden movement, where the whole ice cap moves
equatorward, it would melt whole, but a new ice cap would form on the
vacant pole.

So, over geological time frames, you can expect there to always be an ice
cap. Just don't bank on building a permanent settlement there.

[david.sh...@ymail.com]

On Sep 27, 2:21 pm, Aleksandar Kuktin <akuk...@gmail.com> wrote:
> Hello group!

> The polar ice cap would be in a steady state with reguard to the
> surrounding ocean. If it is moving in a certain direction, the ice on the
> leading edge would melt, but it would be replaced by newly forming ice on
> the trailing edge of the ice cap. A section of the ice cap, however would
> eventualy melt as it moves from the trailing edge to the leading edge.
> Any city build on this section of ice would also eventually sink.

This is to some extent true of our arctic ice cap. While, even during
the summer it extends to the north coasts of Greenland and the
northern
Canadian islands, there is substantial drift. Enough drift, that
Nansen's expedition in the Fram traveled a substantial distance from
the New Siberian Islands to Spitzbergen, locked in the pack ice.

Also see <http://www.arctic.noaa.gov/detect/ice-seaice.shtml> for,
among other things, an animation of the ice motions.

[Aleksandar Kuktin]

Perhaps debye relaxation-prone materials can affect the propagation of
electromagnetic waves.

Now, I don't know enough physics/mathematics to tell if a layer of ice-VI
would atenuate or help propagate EM waves (especially with comparion to
liquid water), but I reckon it would do one of the two.

[JRStern]

Well, that is something. Of course it doesn't keep on getting colder
since it's still liquid. How IS it that it gets colder, when on land
it does not, that nasty convection? If so it has also managed to
continue to cool the ocean floor, which we assume would also be
warmer, 35,000 feet down. Interesting question, actually.

> Cold water sinks... but ice floats, usually. The
>density of Ice VI is greater than that of standard water; not sure if
>it's greater than that of water at that depth. Have to check. Water
>doesn't compress MUCH, but it will compress.
>
>>
>> OTOH, following your lead, the entire planet may cool much faster with
>> that much water. OTOOH, if Ice XXX does manage to form, it won't be
>> convecting much faster than stone. Or will it?
>>
>> Then there's this:
>>
>> http://www.nationalgeographic.com/explorers/bios/kevin-hand/
>>
>> “Europa is about the size of our own moon,” Hand explains. “Its vast
>> ocean is likely more than 60 miles deep (Earth’s ocean depths reach
>> only about seven miles). That means Europa may harbor two to three
>> times the volume of all liquid water on Earth.”
>
> That's because Europa has roughly 1/8th Earth Normal gravity, so the
>pressure at the bottom of that ocean will only be roughly that of an
>Earthly ocean 5 miles deep or so -- which being a little over 26,000
>feet is considerably less than the deepest our oceans actually get here
>(36,000 feet or nearly two miles deeper).

True, just that it actually occurs, and even locally, and possibly to
greater depths.

I should have mentioned the lower gravity as well as the radioactives,
the whole planetary density issue. Suppose it also matters what's on
top, for all we know Jupiter has oceans of liquid water a hundred
miles deep, with immense atmospheric pressure above helping with the
liquidity.

J.

[Sea Wasp (Ryk E. Spoor)]

Yep. Cold water sinks, hot rises. Which is why you get hotter as you go
down in land -- you're at the TOP of the mantle, just getting through
that very, very thin, cooled crust at the top.

Because of this, I would expect the oceans to be cold at the bottom
even with very deep oceans, until they solidified under pressure... and
then other factors come into play.

Oh, this is gonna be FUN.

[Cryptoengineer]

On Sep 27, 4:36 pm, "Sea Wasp (Ryk E. Spoor)"

<seaw...@sgeinc.invalid.com> wrote:
> On 9/27/12 3:58 PM, JRStern wrote:
>
>
>
>
>
>
>
>
>
> > On Thu, 27 Sep 2012 11:10:43 -0400, "Sea Wasp (Ryk E. Spoor)"
> > <seaw...@sgeinc.invalid.com> wrote:
>
> >> On 9/27/12 10:44 AM, JRStern wrote:

> >>> On Tue, 25 Sep 2012 20:28:25 GMT, thro...@sheol.org (Wayne Throop)

> >>> wrote:
>
> >>>> :: You can certainly get a world with liquid water that has great depth
> >>>> :: -- many miles.  But (assuming roughly earth-normal gravity) at about
> >>>> :: 60 miles or so, at temperatures around what we consider normal, it'll
> >>>> :: start to turn to Ice VI, later to Ice VII and possibly others
> >>>> :: depending on temperature and exact pressure and so on.  (see a phase
> >>>> :: diagram of water for exact numbers and such)
>

> >>>> : JRStern <JRSt...@foobar.invalid>

Assuming stratification does not take place, the deeper the ocean/
smaller the world, the more effective the cooling should be, since the
area of the ocean surface (where it radiates heat) is larger than the
area of the underlying solid planet.

Think about life forms which play with the phase table for biological
reasons; for example, one which has chamber where water can be changed
from Ice III to liquid to lower density, perhaps by adding or removing
antifreeze compounds to the chamber, thus varying the creature's
buoyancy. Or using highly pure ice to form skeletons, while the rest
of its body and the surrounding ocean remains fluid due to salt
content.

pt

[Aleksandar Kuktin]

On Thu, 27 Sep 2012 13:59:27 -0700, Cryptoengineer wrote:

> [snip]

> Or using highly pure ice to form skeletons, while the rest of
> its body and the surrounding ocean remains fluid due to salt content.
>
> pt

My brain just experienced a segmentation fault and crashed.

[Cryptoengineer]

Not quite the same, but there are Antarctic fish that live in sea
water below 0C by producing antifreeze compounds in their bodies.

The physical properties of non-standard ice crystal habits at the
extreme pressures SW envisages may be quite different than the brittle
stuff we're used to.

pt

[JRStern]

But then, just noodling, the oceans have been semi-actively cooling
3/4 of the Earth's crust for the past billions of years. And must
continue to do so today. Certainly including where volcanoes and
vents spew heat directly. Does that slowly affect even plate
tectonics, or is the crust just so thin it really doesn't much matter?

Wow a sub-genre of geologic sf.

J.

[Sea Wasp (Ryk E. Spoor)]

The cooling is significant only on VERY long timescales, I think. The
planet in question is quite geologically active.

[Wayne Throop]

:: But then, just noodling, the oceans have been semi-actively cooling

:: 3/4 of the Earth's crust for the past billions of years. And must
:: continue to do so today. Certainly including where volcanoes and
:: vents spew heat directly. Does that slowly affect even plate
:: tectonics, or is the crust just so thin it really doesn't much
:: matter?

More that it is so thick it doesn't matter (depending on
which things are in the set of things-that-might-matter-in-this-context).

: "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com>
: The cooling is significant only on VERY long timescales, I think.

: The planet in question is quite geologically active.

That might make a difference. On earth, given the size of the plates
and any plausible rate of sea-floor spreading, the bottleneck in heat
loss is going to be conductivity through mumble kilometers of crust.
Since the crust is not liquid, it doesn't convect. Compare to volcanic
lava fields; the surface crusts over, and then the rock underneath can
remain liquid for quite a while. And that's without any radioactive
elements decaying in siginficant amounts, and with only a few centimeters
thickness of solid overlaying.

So. The earth as a whole is much like that. If you have something
over the crust that's convective, the crust will bottleneck the heat
from the underlying magma, and it'll have vaguely (give or take a couple
hundred degrees) the same temperature as we've got either at the air-rock
interface, or at the water-rock interface, here on earth.

Now, if the planet in question is very geologically active, as in,
has incredibly fast tectonic motions, and sea floor spreading in some
sort of fractal pattern so it can have actual magma escaping all over
the place instead of in a single thin line... well... it'd be very
different. In fact, it'd be so different it'd be difficult to say
what all the side effects of that would be.

I recall a 1970s Analog short story about a planet where the tectonic
plates were about the size of large islands, and moved... very VERY
fast indeed. Some of them had steering mechanisms of some sort put on
them, etc, etc. I have no idea how plausible that would be.
Not very, I vaguely expect.

[JRStern]

On Thu, 27 Sep 2012 20:10:00 -0400, "Sea Wasp (Ryk E. Spoor)"
<sea...@sgeinc.invalid.com> wrote:

>> But then, just noodling, the oceans have been semi-actively cooling
>> 3/4 of the Earth's crust for the past billions of years. And must
>> continue to do so today. Certainly including where volcanoes and
>> vents spew heat directly. Does that slowly affect even plate
>> tectonics, or is the crust just so thin it really doesn't much matter?
>
> The cooling is significant only on VERY long timescales, I think. The
>planet in question is quite geologically active.

Sounds tricky.

What is the temperature even 1km under the bottom of the Marianas
Trench, or under the Antarctic sea bed, or wherever the coldest water
is now. Under a 100km deep ocean, with the ground temperature
otherwise over 2000c, you're going to have to have a lot of convection
to keep that water near freezing, and ice forming and killing the
convection, would seem likely to melt again soon. Kind of like snow
in Washington DC.

J.

[Wayne Throop]

: JRStern <JRS...@foobar.invalid>
: What is the temperature even 1km under the bottom of the Marianas

: Trench, or under the Antarctic sea bed, or wherever the coldest water
: is now. Under a 100km deep ocean, with the ground temperature
: otherwise over 2000c, you're going to have to have a lot of convection
: to keep that water near freezing, and ice forming and killing the
: convection, would seem likely to melt again soon. Kind of like snow
: in Washington DC.

Why would ice formation kill the convection? Ice is lighter than water,
so it wouldn't stick down there stably; it'd tend to break off and
float up. Hm. Maybe you mean some of the exotic ices are denser
than water, and might insulate as well or better than rock... in which
case, no more than a kilometer or so of ice could coat the sea floor.
Because then heat would build up under it, and destabilize it.
At least, over a megayear or less.

I also think you are vastly overestimating how much heat is pouring out
from the earth, or even something much more active than earth. Take earth
as an example, on average over the surface, it's only 0.075 watts / m^2.
True, at seafloor spreading sites, it's much higher than average, but at
subduction zones, I doubt it's that much higher than the average. If you
pile enough rock on top of something, it'll insulate it remarkably well.

I'm not at all sure where the "ground temperature otherwise over 2000c"
comes from. Seems very unlikely. Sure, you could have that if there
were something insulating the surface... but air doesn't insulate,
nor does water, nor does vacuum (remember, you have 75 milliwatts per
square meter... look at the black body equilibrium temperature for that.
I'm pretty sure it's not 2000c; I mean, even without running the numbers,
think of putting a 75 mW resistive heater on each square meter of the
moon's surface). I don't think it'll get very hot.

So. Like I said. Not sure (nor is it at all clear) where the "otherwise
2000c" comes from. Under what circumstance would it be 2000c? The only
one that comes to mind is if it had several kilometers of rock on top.
Gas, liquid, or vacuum wouldn't do it. And since the context here is
at the top of any solid rock layers, it can't have rock over it.
Nor anything that melts significantly before 2000c.

[Howard Brazee]

Depending on how cold it is. When water gets below 4 degrees C, it
expands. That is why ice floats. And it's why the arctic has so
much more fish than the tropics, as cold water at the bottom goes to
the top, bringing up nutriments as it goes.

--
"In no part of the constitution is more wisdom to be found,
than in the clause which confides the question of war or peace
to the legislature, and not to the executive department."

- James Madison

[Dimensional Traveler]

My personal first thought is that you'd always have ice at the poles, it
just would always be the _same_ ice.

[Dimensional Traveler]

But it is mostly surrounded by land and anchored to that.

[P. Taine]

On 27 Sep 2012 03:34:05 GMT, "John F. Eldredge" <jo...@jfeldredge.com> wrote:

>On Wed, 26 Sep 2012 17:46:05 +0000, Wayne Throop wrote:
>
>> ::: A depth of 20 miles with a few scattered islands peeking out would

>> ::: be feasible. more than that, probably not. I could imagine some
>> ::: mechanisms to provide very occasional super-high mountains, but they
>> ::: wouldn't last for even human timescales, let alone geologic.
>>

>> :: The islands could be dynamically supported by mantle plumes. :: Or

>> the tectonics could be otherwise very non-earthlike.
>>

>> : Andrew Plotkin <erky...@eblong.com> : Floating islands.
>>
>> Oooh, cool.
>>
>> : Not that I have any idea how to produce *them* on a deep-ocean world.

>> : I guess you start by figuring out a plausible mechanism for a :
>> twenty-mile-high convection cycle -- get minerals and nutrients up :
>> from the sea-floor to the lighted zone -- and then invent big, big :
>> algae. Let floating seaweed mat up and "petrify", or dry out anyhow. :
>> Maybe a population of microorganisms that like to cling to the roots :
>> and bubble.
>>

>> Giant turtles. Xref "Mysteries of the Arcana" (where it's turtles all
>> the way down,
>> http://mysteriesofthearcana.com/index.php?action=comics&cid=231 And also
>> xref The Last Airbender, and the giant lion-turtle therein. And David
>> Duncan's "West of January", where all the cities are built on turtles.
>
>Pumice, plus some plant that tends to grow in a network around
>collections of pumice? You would get a fairly flat island, but it would
>float.

Isn't that "The Fata Morgana" by Frankowski?

[Greg Goss]

Up until the last few years, it's been encircled by bedrock.
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.

[JRStern]

On Fri, 28 Sep 2012 00:55:04 GMT, thr...@sheol.org (Wayne Throop)
wrote:

>I'm not at all sure where the "ground temperature otherwise over 2000c"

Presumed temperature on Earth 60 miles down, might be more like 2500c
per simple number from Wikipedia of 25c/km.

>comes from. Seems very unlikely. Sure, you could have that if there
>were something insulating the surface... but air doesn't insulate,
>nor does water, nor does vacuum (remember, you have 75 milliwatts per
>square meter... look at the black body equilibrium temperature for that.
>I'm pretty sure it's not 2000c; I mean, even without running the numbers,
>think of putting a 75 mW resistive heater on each square meter of the
>moon's surface). I don't think it'll get very hot.

So you argue that the 60 miles (100km) is insignificant, that the
water will convect away a lot more heat than rock anyway, so under
100km of water you have to a first approximation an Earth-like crust
still limiting core radiation to something like 75mw/meter. My
interpretation (if that's what it was) was that it would somehow be
much higher. Perhaps you're right. But still, if you apply even
75mw/meter to the bottom of a solid mass of ice, what happens? I
dunno, but SW might want to figure it out. It might be enough to
throw off his subocean ice, or what do you think?

J.

[Wayne Throop]

: JRStern <JRS...@foobar.invalid>
: Presumed temperature on Earth 60 miles down, might be more like 2500c

: per simple number from Wikipedia of 25c/km.

Right. Under 60 miles of insulating rock. But the example for which
you're saying the temperature will "otherwise" be 2000c is under zero
miles of insulating rock. Do you mean so mething like, "if only there
were 60 miles of insulating rock, which there isn't"?

: So you argue that the 60 miles (100km) is insignificant,

I argued no such thing. I argued that 100km of rock will have different
thermal properties than 100km of water. As is obvious on earth; if water
acted like rock, the temperature in the marianas trench would be >100c,
whereas it's much closer to 4c.

: But still, if you apply even 75mw/meter to the bottom of a solid mass

: of ice, what happens? I dunno, but SW might want to figure it out.
: It might be enough to throw off his subocean ice, or what do you
: think?

I agree, it seems unlikely that thick enough sea floor ice would be stable
under 75mW/m^2, since the lack of convection would allow heat to build
up under the ice. Assuming that you don't have the "ice is lighter than
water" issue, because we're talking a layer of Ice-N for some values of N,
then depth in that *ice* could very likely be more like depth in rock than
depth in water. Meaning, the ice layer couldn't be more than a few
kilometers deep at most, before it became unstable, simply because
it would melt at lower temperatures than rock.

But I don't recall he said how deep the ice layer was. Did he?


Destination unknown, as we pull in for some gas
Freshly pasted poster reveals a smile from the past
Elephants and acrobats, lions snakes monkey
Pele speaks "righteous," Sister Zina says "funky"
How bizarre; How bizarre, how bizarre

--- OMC, "How Bizarre"

[Gene Wirchenko]

On Thu, 27 Sep 2012 15:56:01 -0700, JRStern <JRS...@foobar.invalid>
wrote:

>On Thu, 27 Sep 2012 16:36:41 -0400, "Sea Wasp (Ryk E. Spoor)"
><sea...@sgeinc.invalid.com> wrote:

[snip]

>> Oh, this is gonna be FUN.
>
>But then, just noodling, the oceans have been semi-actively cooling
>3/4 of the Earth's crust for the past billions of years. And must
>continue to do so today. Certainly including where volcanoes and
>vents spew heat directly. Does that slowly affect even plate
>tectonics, or is the crust just so thin it really doesn't much matter?
>
>Wow a sub-genre of geologic sf.

Planet porn?

Sincerely,

Gene Wirchenko

[Wayne Throop]

:: But then, just noodling, the oceans have been semi-actively cooling

:: 3/4 of the Earth's crust for the past billions of years. And must
:: continue to do so today. Certainly including where volcanoes and
:: vents spew heat directly. Does that slowly affect even plate
:: tectonics, or is the crust just so thin it really doesn't much
:: matter? Wow a sub-genre of geologic sf.

: Gene Wirchenko <ge...@ocis.net>
: Planet porn?

You mean, sort of like "Planet X", where X = nekkid people?

ANYhoo... I got the idea that the cause of the supercontinent cycle(s)
was heat buildup under landmasses... but I suppose the same could be said
in reverse, it's due to cooling under oceanmasses.

But that has to be oversimplistic, since you still get sea-floor spreading
continuing for megayears, despite by then the hottest bits being in the
middle of a seriously large expanse of ocean. So if you can't trust
an ocean to cool down a mantle plume in a few megayears, who *can*
you trust?

So... probably it's one of those things where the best summary
is "it's complicated".

"I'm an evil villain bent on bringing pain and suffering
to an unsuspecting world... if you can't trust me,
who *can* you trust?"
--- Dark Lord Chuckles, The Silly Piggy

[David DeLaney]

Sea Wasp (Ryk E. Spoor) <sea...@sgeinc.invalid.com> wrote:
>On 9/27/12 2:12 PM, nu...@bid.nes wrote:
>> Suppose there's sufficient irregularly-distributed stuff [element,
>> compound, whatever] on your world to dope benthic ice at a particular
>> stage in transition between VI and VII so that it becomes strongly
>> ferromagnetic (maybe by linking the disordered separate latices so all
>> the proton spins can align?), strongly enough to produce a noticeable
>> (/usable) field wherever your drama occurs; surface or the deeps. You
>> would probably get multiple magnetic poles. It occurs to me that
>> quakes would strongly alter the magnetic field by moving the critical
>> pressure up or down (or sideways) through ices with the proper dopant
>> concentration, making navigation more "interesting" for all involved.
>> You could get auroras at all latitudes, moving with the field
>> changes...
>>
>> What to use as a dopant? I don't know. Doc Smith got away with
>> claiming that a little Rhenium made a super-strong alloy (Leybyrdite)
>> at least partly because nobody could gather enough Rhenium to call BS
>> on him. Pick something fairly exotic.

You're thinking multiple magnetic poles. I'm thinking an ice-incarnated
computing system, forming over aeons a planetary AI...

> Actually, one of his favorites was an osmium-iridium alloy -- both of
>them even farther down the charts!

Osmium, Iridium, Platinum is the second-down trio from iron, cobalt, nickel,
right?

Dave
--
\/David DeLaney posting from d...@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

[Jens Kleimann]

So the current consensus seems to be that a) Earth is not a good example to settle this since the ice layers of both of its poles can only drift slightly because they are frozen to either land masses or bedrock below it, and that b) ice from the poles is likely to gradually drift away equatorwards and melt, while being continuously replenished by newly formed ice at the poles. This indicates that the two crucial numbers to compare would be the rate at which new ice forms vs. the velocity at which it gets carried away. Can one speculate about the magnitude and flow pattern of near-surface ocean circulation on an all-water (but otherwise more or less Earth-like) planet? With a deep and even sea floor, and in the absence of continental flow barriers, I'd expect them to be rather smooth and uniform, but I'm unsure as to how this could be determined more accurately.

Jens.
--
Remove '_nospam' for actual email address.

[Wayne Throop]

: d...@gatekeeper.vic.com (David DeLaney)
: You're thinking multiple magnetic poles. I'm thinking an

: ice-incarnated computing system, forming over aeons a planetary AI...

You mean self-assembled and/or evolved over aeons?
In which case, in what sense is it an AI?

[Paul Colquhoun]

Given the cold conditions, wouldn't there be a general surface current
towards the poles, from all directions, where the water would cool and
sink, to then flow towards the equator and resurface there.


--
Reverend Paul Colquhoun, ULC. http://andor.dropbear.id.au/~paulcol
Asking for technical help in newsgroups? Read this first:
http://catb.org/~esr/faqs/smart-questions.html#intro

[Sea Wasp (Ryk E. Spoor)]

Hundred mile deep ocean, so slightly less than 40 miles.

Yes, it won't be stable. Yet it won't be entirely UNstable, so to
speak. As I said, this is going to be FUN.

[Jens Kleimann]

You mean something like the marine version of a Hadley cell? Sounds reasonable. This would then act to stabilize a floating polar cap. And Coriolis forces, if of any importance at all, will tend to zero near the poles. So there's hope that an ice cap, once formed, can hope to stay there for quite some time. Nice!

[JRStern]

On Fri, 28 Sep 2012 06:51:12 -0400, "Sea Wasp (Ryk E. Spoor)"
<sea...@sgeinc.invalid.com> wrote:

>> But I don't recall he said how deep the ice layer was. Did he?
>>
>
>
> Hundred mile deep ocean, so slightly less than 40 miles.
>
> Yes, it won't be stable. Yet it won't be entirely UNstable, so to
>speak. As I said, this is going to be FUN.

When you said hundred miles deep ocean, I thought that was *to* the
ice, not including the ice.

J.

[Sea Wasp (Ryk E. Spoor)]

I started with 100-mile deep water. Then I looked at the behavior of
water in the phase diagram and realized that at slightly over 60 miles
down (assuming roughly Earth gravity) it's no longer liquid.

[JRStern]

On Fri, 28 Sep 2012 05:07:52 GMT, thr...@sheol.org (Wayne Throop)
wrote:

On Fri, 28 Sep 2012 05:07:52 GMT, thr...@sheol.org (Wayne Throop)
wrote:

>: JRStern <JRS...@foobar.invalid>
>: Presumed temperature on Earth 60 miles down, might be more like 2500c
>: per simple number from Wikipedia of 25c/km.
>
>Right. Under 60 miles of insulating rock. But the example for which
>you're saying the temperature will "otherwise" be 2000c is under zero
>miles of insulating rock. Do you mean so mething like, "if only there
>were 60 miles of insulating rock, which there isn't"?

Yes.

>: So you argue that the 60 miles (100km) is insignificant,
>
>I argued no such thing. I argued that 100km of rock will have different
>thermal properties than 100km of water. As is obvious on earth; if water
>acted like rock, the temperature in the marianas trench would be >100c,
>whereas it's much closer to 4c.

Yes of course, I was trying to be brief, as the situation is (more or
less) given.

>I agree, it seems unlikely that thick enough sea floor ice would be stable
>under 75mW/m^2, since the lack of convection would allow heat to build
>up under the ice. Assuming that you don't have the "ice is lighter than
>water" issue, because we're talking a layer of Ice-N for some values of N,
>then depth in that *ice* could very likely be more like depth in rock than
>depth in water. Meaning, the ice layer couldn't be more than a few
>kilometers deep at most, before it became unstable, simply because
>it would melt at lower temperatures than rock.
>
>But I don't recall he said how deep the ice layer was. Did he?

I'm just wondering at the lower bound there, a kilometer of ice is
still a lot of ice, would it be less than one kilometer, maybe down to
a couple of feet, or less, before you get a small melt layer? Maybe
that's all the situation supports, a shell of a few feet of ice XXX
with liquid water beneath?

J.

[Wayne Throop]

: JRStern <JRS...@foobar.invalid>
: I'm just wondering at the lower bound there, a kilometer of ice is

: still a lot of ice, would it be less than one kilometer, maybe down to
: a couple of feet, or less, before you get a small melt layer? Maybe
: that's all the situation supports, a shell of a few feet of ice XXX
: with liquid water beneath?

Yeah, just like on earth, the 75mW/m&2 means you can't have more
than a few feet thick glacier before it turns to water underneath.
Those reports of kilometers-thick glaciers, or the antarctic ice,
are exagerations, no doubt.

[Sea Wasp (Ryk E. Spoor)]

I sense much.... *SARCASM* from you.

"Oh, yeah, a sarcasm detector. THAT'LL be useful."

[JRStern]

On Fri, 28 Sep 2012 14:57:26 GMT, thr...@sheol.org (Wayne Throop)
wrote:

The ambient temperature above the glaciers is far lower than 0c, with
more conduction, convection, and radiation.

Even so, I see your point. So we come back to the need for an
earthlike crust to form below this very deep ocean. I lack both facts
and intuition to have any certainty that this could occur. You seem
pretty certain about your positions. Are they really that clear? I'm
just asking.

For that matter I have only the sketchiest idea of what the state of
the art knowledge is about the Earth's internal heat budget, it's
relatively "news" to me that more of it was from radioactives than
heat of formation/compression. And once you have a little of that,
why not more or less, as you like.

J.

[Stephen Graham]

On 9/28/2012 12:03 AM, David DeLaney wrote:
> You're thinking multiple magnetic poles. I'm thinking an ice-incarnated
> computing system, forming over aeons a planetary AI...

The existence of such a thing is one of the central and unresolved plot
points of Paul McAuley's _In the Mouth of the Whale_.

[Wayne Throop]

: JRStern <JRS...@foobar.invalid>
: So we come back to the need for an earthlike crust to form below this

: very deep ocean. I lack both facts and intuition to have any
: certainty that this could occur. You seem pretty certain about your
: positions. Are they really that clear? I'm just asking.

The conclusions I have some confidence in are quite generic and vague,
like water has very very different thermal behavior than rock, etc.
Or alternatively, conclusions by analogy with known processes on earth,
such as the thickness of ice cover and tempersture with depth in water.

In this case, I don't see anything *preventing* a rock crust from
forming under a deep ocean. What sorts of difficulties do you foresee?

One thing to note is that there seems to be reason to suppose venus'
*lack* of an ocean made it's crust very thick and the rock less plastic,
leading to locking it's plates in place early. So possibly in places
you don't talk about at parties, you *want* that ocean, you *need*
that ocean...

: For that matter I have only the sketchiest idea of what the state of

: the art knowledge is about the Earth's internal heat budget, it's
: relatively "news" to me that more of it was from radioactives than
: heat of formation/compression. And once you have a little of that,
: why not more or less, as you like.

You mean internal heat production can plausibly vary from planet to
planet? I expect it'd depend on the mix of radioactive isotopes the
material forming planets has, which in turn might depend on how recent
and how violent the supernova(s) was/were that went into that material.
Seems reasonable it'd vary from place to place. And of course, half
life of the isotopes vs age of the crusting-over of the planet. So,
lots of room for fudging those numbers, to turn tectonic activity up
or down, among other things.

[Wayne Throop]

::: Maybe that's all the situation supports, a shell of a few feet of

::: ice XXX with liquid water beneath?

:: Yeah, just like on earth, the 75mW/m&2 means you can't have more than
:: a few feet thick glacier before it turns to water underneath. Those
:: reports of kilometers-thick glaciers, or the antarctic ice, are
:: exagerations, no doubt.

: "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com>
: I sense much.... *SARCASM* from you.

Who... Meeee? Nah, couldn't be.
I would rather think that a yankee professor would lie,
than that there could be kilometer-thick ice on earth...

[John F. Eldredge]

On Thu, 27 Sep 2012 16:36:41 -0400, Sea Wasp (Ryk E. Spoor) wrote:

> On 9/27/12 3:58 PM, JRStern wrote:
>> On Thu, 27 Sep 2012 11:10:43 -0400, "Sea Wasp (Ryk E. Spoor)"
>> <sea...@sgeinc.invalid.com> wrote:
>>
>>> On 9/27/12 10:44 AM, JRStern wrote:
>>>> On Tue, 25 Sep 2012 20:28:25 GMT, thr...@sheol.org (Wayne Throop)
>>>> wrote:
>>>>
>>>>> :: You can certainly get a world with liquid water that has great
>>>>> depth :: -- many miles. But (assuming roughly earth-normal gravity)
>>>>> at about :: 60 miles or so, at temperatures around what we consider
>>>>> normal, it'll :: start to turn to Ice VI, later to Ice VII and
>>>>> possibly others :: depending on temperature and exact pressure and
>>>>> so on. (see a phase :: diagram of water for exact numbers and such)
>>>>>
>>>>> : JRStern <JRS...@foobar.invalid>
>>>>> : What is the normal temperature, on Earth, at 60 miles?
>>>>>
>>>>> I note that since water convects much faster than rock, comparing
>>>>> temperatures 60 km depth in rock to 60 km depth in water is quite
>>>>> like comparing apples to bicycles.
>>>>
>>>> Yeah but you've got to start somewhere.
>>>>
>>>> SW said "at temperatures around what we consider normal", I suppose
>>>> meaning 25c. Problem is that at first approximation, temperature on
>>>> Earth in the mantle goes up about 25c per kilometer, per
>>>> Google/Wikipedia. Giving us roughly 2500c 60 miles down. May impact
>>>> his Ice VI scenario.
>>>
>>> But in the oceans, it gets COLDER the lower you go. To a minimum
of
>>> slightly above freezing for the particular concentration of salt.
>>> I.e., if you go down a kilometer in the Earth your temperature goes up
>>> by 25c, if you go down a kilometer in the ocean you may find your
>>> temperature goes DOWN by 25c.

>>
>> Well, that is something. Of course it doesn't keep on getting colder
>> since it's still liquid. How IS it that it gets colder, when on land
>> it does not, that nasty convection?
>
> Yep. Cold water sinks, hot rises. Which is why you get hotter as
you go
> down in land -- you're at the TOP of the mantle, just getting through
> that very, very thin, cooled crust at the top.
>
> Because of this, I would expect the oceans to be cold at the
bottom
> even with very deep oceans, until they solidified under pressure... and
> then other factors come into play.
>

> Oh, this is gonna be FUN.

If you have localized sea-bottom volcanic activity, you might have
scattered pockets of liquid water, surrounded by ice. If such pockets
remained isolated from each other most of the time, you could end up with
much the same sort of evolutionary divergence as happens from scattered
land masses.


--
John F. Eldredge -- jo...@jfeldredge.com
"Reserve your right to think, for even to think wrongly
is better than not to think at all." -- Hypatia of Alexandria

[JRStern]

On Fri, 28 Sep 2012 18:40:11 GMT, thr...@sheol.org (Wayne Throop)
wrote:

>: JRStern <JRS...@foobar.invalid>
>: So we come back to the need for an earthlike crust to form below this
>: very deep ocean. I lack both facts and intuition to have any
>: certainty that this could occur. You seem pretty certain about your
>: positions. Are they really that clear? I'm just asking.
>
>The conclusions I have some confidence in are quite generic and vague,
>like water has very very different thermal behavior than rock, etc.
>Or alternatively, conclusions by analogy with known processes on earth,
>such as the thickness of ice cover and tempersture with depth in water.
>
>In this case, I don't see anything *preventing* a rock crust from
>forming under a deep ocean. What sorts of difficulties do you foresee?

In the interests of not assuming, I tend to start by assuming (!) the
opposite of the given. In this case, start with the observation that
temperature rises as you go down even a few thousand feet in the crust
here on Earth, and yet as has been pointed out, do the same in the
ocean and the temperature goes down. Well, there has to be some sort
of limit to that, doesn't there? What if we borrowed the charge
suppressor from Ringworld and cut a 100 mile deep trench in the
Earth's ocean, a couple of miles wide. That's right through the
current crust, and it would be hot on both sides, to begin. Would the
crust in effect "heal", even with that trench still open, develop
miles-thick crust on both sides insulating? I guess so.

(actually I guess magma would well up and fill it most of the way back
to the surface, let's assume unmagmanimously it doesn't do so, due to
obscure secondary effects of the magic trencher)

What would be the equilibrium temperature, would SW get his Ice VI, or
would there be MUCH more conduction of heat that far down for reasons
of pressure, or because of the geometry, or for some other obscure
reason? I guess (!) it is conduction and the radioactive heating is
mostly (all) at the core, if it were also ongoing throughout the
mantle at even modest rates that would change the answer, I think.

So there's possibly one scenario with a 100 mile deep world ocean, and
another if the great depth is more localized. OTOH perhaps that
mostly doesn't happen, for the same reasons that force planets even
smaller than Earth into spheres in the first place. But if you take
up a significant amount of crustal depth with water, do you still get
the same crustal thickness underneath? I hesitate to assume that,
intuitively I guess, I have to dig somewhat for reasons after the
fact.

[Wayne Throop]

: JRStern <JRS...@foobar.invalid>
: What if we borrowed the charge suppressor from Ringworld and cut a 100

: mile deep trench in the Earth's ocean, a couple of miles wide. That's
: right through the current crust, and it would be hot on both sides, to
: begin. Would the crust in effect "heal", even with that trench still
: open,

Yes. Note that all existing sea floor on earth was created under water,
at points where the sea floor is beign pulled apart (to a first
approximation). (Well, actually, more like upwelling and sliding
down a (slight) incline, but still... the raw magma gets solidified,
and there's no particular reason it shouldn't under deeper water also.)

: (actually I guess magma would well up and fill it most of the way back

: to the surface, let's assume unmagmanimously it doesn't do so, due to
: obscure secondary effects of the magic trencher)

You can't really carve kilometers-deep features into rock.
It isn't strong enough in 1g. So the excess weight outside the
trenched out area will deform the rock (and/or magma) until the
feature is shallow enough to hold its shape. And given that the
floor of the trench is magma, and has very little strength, that'd
be pretty shallow.

: What would be the equilibrium temperature, would SW get his Ice VI, or

: would there be MUCH more conduction of heat that far down for reasons
: of pressure,

Conduction through what? And why would pressure affect the
thermal conductivity of either water or rock?

: or because of the geometry, or for some other obscure reason? I guess

: (!) it is conduction and the radioactive heating is mostly (all) at
: the core, if it were also ongoing throughout the mantle at even modest
: rates that would change the answer, I think.

The core is mostly iron, and nucleonically stable. The various radioactives
are scattered throughout the mantle, near as I recall.

http://en.wikipedia.org/wiki/Geothermal_gradient
Much of the heat is created by decay of naturally radioactive
elements. An estimated 45 to 90 percent of the heat escaping from the
Earth originates from radioactive decay of elements within the mantle.

Mostly thorium and potassium, with some uranium.
Mean mantle concentrations are listed in a table on the above web page.

: But if you take up a significant amount of crustal depth with water,

: do you still get the same crustal thickness underneath?

Yes.

: I hesitate to assume that,

Not an assumption. It's a conclusion, based on the fact that the temperature
at the top of the rock is somewhere close to 0c, and the heat flow is
a tenth-watt per square meter... that dictates the thickness of the
rock crust that will form. Unless I'm overlooking something.

You know the heat flux through a given surface area, and you know the
insulating properties of solid rock, so you know the temperature gradient
within that rock, so you know how thick it gets before the bottom melts.
Granted, I'm not churning actual numbers, but since we're postulating
rock similar to that on earth, and heat flux similar to that on earth,
you'll get similar thickness. Seawasp sez, more tectoncially active
than earth, so that might imply higher heat flux, so the crust might be
thinner, but I don't think that much thinner... and most of the excess
heat would have to come up at tectonically active fetures such as mangle
plumes or seafloor spreading sites.

[Charles Bishop]

In article <k3ss2a$27g$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)"
<sea...@sgeinc.invalid.com> wrote:

>On 9/25/12 2:31 PM, Charles Bishop wrote:
>> In article <k3n1m3$ri9$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)"
>> <sea...@sgeinc.invalid.com> wrote:
>>
>>> According to my examination of the phase tables for water, in
an ocean
>>> under ~1g and in the 300k or so range, a little more than 60 miles down
>>> it will turn into Ice VI, and deeper (250 miles?) to Ice VII.
>>>
>>> Both of these exhibit Debye Relaxation, according to wiki and other
>>> sources.
>>>
>>> Are there any interesting implications of this with respect to the
>>> phenomena to be expected on such a planet? I'm not talking about what a
>>> Debye Relaxation-prone material can do in lab circumstances but about
>>> large masses in a real-world environment, possibly covered to some depth
>>> on top with accumulated sediments (possibly, depending on circumstances,
>>> compacted to rock of some sort) and far down resting on bedrock or the
>>> equivalent of mantle material (turning to supercritical fluid if it's
>>> overheated, of course).
>>
>> Not to derail the original question, but I have a sub-question. Is it
>> possible to have a earth type world (liquid water, &c.) that can have a
>> 250 mile deep ocean, or a 60 mile deep one? That is, that deep in places,
>> much the same that the Marianas trench is a deep part of the Pacific
>> Ocean.
>>
>
> Well, depends on how Earthlike. You're not going to get
continents with
>dry land and oceans that are a hundred miles deep; the continents will
>sink down because they represent WAY too much mass to be supported
>(continents may seem solid to us, but they're really just thin crusts
>floating on plastic, near-liquid mantle and thus if they get too thick,
>they sink down).

>
> You can certainly get a world with liquid water that has great
depth --
>many miles. But (assuming roughly earth-normal gravity) at about 60
>miles or so, at temperatures around what we consider normal, it'll start
>to turn to Ice VI, later to Ice VII and possibly others depending on
>temperature and exact pressure and so on. (see a phase diagram of water
>for exact numbers and such)

If I may restate: You can't have continents and a 250 mile deep ocean
because the continents will sink, yes? and you're left with a water world.

It is posssible to have continents and a 60 mile deep ocean?

I suppose given the vastness of the universe, "possible" is probable.

--
charles

[Charles Bishop]

In article <k3usu8$t40$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)"
<sea...@sgeinc.invalid.com> wrote:

>On 9/26/12 8:29 AM, Michael Stemper wrote:
>> In article <k3ss2a$27g$1...@dont-email.me>, "Sea Wasp (Ryk E. Spoor)"

<sea...@sgeinc.invalid.com> writes:
>>> On 9/25/12 2:31 PM, Charles Bishop wrote:
>>
>>>> Not to derail the original question, but I have a sub-question. Is it
>>>> possible to have a earth type world (liquid water, &c.) that can have a
>>>> 250 mile deep ocean, or a 60 mile deep one? That is, that deep in places,
>>>> much the same that the Marianas trench is a deep part of the Pacific
>>>> Ocean.
>>

>>> You can certainly get a world with liquid water that has great depth --
>>> many miles. But (assuming roughly earth-normal gravity) at about 60
>>> miles or so, at temperatures around what we consider normal, it'll start
>>> to turn to Ice VI, later to Ice VII and possibly others depending on
>>> temperature and exact pressure and so on. (see a phase diagram of water
>>> for exact numbers and such)
>>

>> So, Nevia, as described, is right out?
>>
>
> I'm not sure what the actual depth of Nevia's oceans was, since I
don't
>have _Triplanetary_ to hand. A depth of 20 miles with a few scattered

>islands peeking out would be feasible. more than that, probably not. I
>could imagine some mechanisms to provide very occasional super-high
>mountains, but they wouldn't last for even human timescales, let alone
>geologic.

That's the part I was wondering about, whether geologic forces would
eventually "even out" the surface with bumps some percentage of the radius
of the planet. Would you expect higher mountains on a smaller, thus lower
gravity, planet? Much like the much larger mountains on Mars. Though this
is helped by limited erosion, isn't it?

--
charles

[Charles Bishop]

In article <achvpc...@mid.individual.net>, "John F. Eldredge"
<jo...@jfeldredge.com> wrote:

>On Wed, 26 Sep 2012 17:46:05 +0000, Wayne Throop wrote:
>
>> ::: A depth of 20 miles with a few scattered islands peeking out would

>> ::: be feasible. more than that, probably not. I could imagine some
>> ::: mechanisms to provide very occasional super-high mountains, but they
>> ::: wouldn't last for even human timescales, let alone geologic.
>>

>> :: The islands could be dynamically supported by mantle plumes. :: Or

>> the tectonics could be otherwise very non-earthlike.
>>

>> : Andrew Plotkin <erky...@eblong.com> : Floating islands.
>>
>> Oooh, cool.
>>
>> : Not that I have any idea how to produce *them* on a deep-ocean world.

>> : I guess you start by figuring out a plausible mechanism for a :
>> twenty-mile-high convection cycle -- get minerals and nutrients up :
>> from the sea-floor to the lighted zone -- and then invent big, big :
>> algae. Let floating seaweed mat up and "petrify", or dry out anyhow. :
>> Maybe a population of microorganisms that like to cling to the roots :
>> and bubble.
>>

>> Giant turtles. Xref "Mysteries of the Arcana" (where it's turtles all
>> the way down,
>> http://mysteriesofthearcana.com/index.php?action=comics&cid=231 And also
>> xref The Last Airbender, and the giant lion-turtle therein. And David
>> Duncan's "West of January", where all the cities are built on turtles.
>
>Pumice, plus some plant that tends to grow in a network around
>collections of pumice? You would get a fairly flat island, but it would
>float.

How much weight could you add befoe the pumice would sink?

Cf. A US congressperson

--
charles

[JRStern]

On Sat, 29 Sep 2012 01:59:19 GMT, thr...@sheol.org (Wayne Throop)
wrote:

>Conduction through what? And why would pressure affect the
>thermal conductivity of either water or rock?

Hey why not. Matter does weird stuff under enough pressure. Like
exotic ices.

>: or because of the geometry, or for some other obscure reason? I guess
>: (!) it is conduction and the radioactive heating is mostly (all) at
>: the core, if it were also ongoing throughout the mantle at even modest
>: rates that would change the answer, I think.
>
>The core is mostly iron, and nucleonically stable. The various radioactives
>are scattered throughout the mantle, near as I recall.
>
> http://en.wikipedia.org/wiki/Geothermal_gradient
> Much of the heat is created by decay of naturally radioactive
> elements. An estimated 45 to 90 percent of the heat escaping from the
> Earth originates from radioactive decay of elements within the mantle.

Escaping, isn't that a qualification? If much of the iron is in the
core because it was more dense, aren't there more radioactives there
too? Or are they just reserving the difference for heat of formation,
gravity, and anything else?

If not then, hmm, I still think that might get interesting, if you
have only partial very deep oceans. Remember, we're just talking
about keeping the temperature above freezing given the pressure.

Or, does this all lead to saying that big, deep oceans cool a core
more quickly? The surface of the Earth we have averages warmer than
0c. I keep wanting to find some big macro effects like this, though
on second thought I guess if the darned planet insists on forming an
insulating crust to water or air, the overall effect can't be that
different.

Let's see, anything else I can dump in the fire? Well just that,
though I can't quite imagine how such a thing would form naturally, if
you had nothing but an iron core say a thousand miles across, and then
water to maybe 10,000 miles diameter to equal the mass of the Earth, I
mean REALLY deep oceans, what then?

Niven's "bigger than worlds" tried to analyze weirder stuff than that,
what was it - The Integral Trees even tried living in some.

I suppose some advanced civilization (of dolphins? er no, better let
whoever have gills ... or maybe not, as follows) might build a super
water world like that, if there would be any interesting point in it.
Which maybe not, if it's all going to be ice VI below sixty miles or
so. Unless you like ice.

I don't generally spend a lot of time building worlds, but hey I guess
it can be fun.

J.

[Wayne Throop]

: JRStern <JRS...@foobar.invalid>
: If much of the iron is in the core because it was more dense, aren't

: there more radioactives there too?

No. Much like, "if nitrogen is less dense than oxygen, why aren't
we living in a 100% oxygen environment, with all the nitrogen far
above our heads?". And why don't people in valleys suffocate on the
carbon dioxide, etc.

: Or are they just reserving the difference for heat of formation,
: gravity, and anything else?

I don't know what the question means.

: Or, does this all lead to saying that big, deep oceans cool a core
: more quickly?

No. The limit is how fast heat can get through rock, not how
cold itis outside the rock. At least, to a reasonable approximation.

: if you had nothing but an iron core say a thousand miles across, and

: then water to maybe 10,000 miles diameter to equal the mass of the
: Earth, I mean REALLY deep oceans, what then?

Then the pressure would be so large in the lower oceans that exotic
ices would form. Near the core, not sure water could exist as such at all.

[Thomas Koenig]

On 2012-09-28, Sea Wasp (Ryk E. Spoor) <sea...@sgeinc.invalid.com> wrote:

>> But I don't recall he said how deep the ice layer was. Did he?

> Hundred mile deep ocean, so slightly less than 40 miles.

> Yes, it won't be stable. Yet it won't be entirely UNstable, so to
> speak. As I said, this is going to be FUN.

Very much so.

A few rough calculations.

For a depth of 100 miles, you'll get around 1.6 GPa of pressure - Ice
VI. Googling gave me a thermal conductivity of ~ 1.5 W/(m*K).

Assume a 60 mile ice sheet and a similar heat flux as the earth
(0.043 W/m^2), the temperature at the bottom of the ice sheet
would be approx 2900 K hotter than on the top. This is not possible,
you would get water vapor. So, no 60 mile ice sheet.

Two to five miles might be possible - 90 to 230 K temperature increase.

[Sea Wasp (Ryk E. Spoor)]

Heh. EXCEPT that as soon as it melts and starts to rise, it cools off.
And immediately solidifies under pressure.

I'm envisioning having a thicker layer that tends to melt at the
bottom, then erupt... maybe catastrophically as large sections of the
sheet separate from bedrock.

Hmm. Is Ice VI more or less dense than liquid water at that pressure?
That is, does Ice VI still have the characteristic that it is lighter
than the liquid it solidifies from? Will it have a tendency to float?

[Aleksandar Kuktin]

On Fri, 28 Sep 2012 09:35:39 +0200, Jens Kleimann wrote:

> So the current consensus seems to be that a) Earth is not a good example
> to settle this since the ice layers of both of its poles can only drift
> slightly because they are frozen to either land masses or bedrock below
> it, and that b) ice from the poles is likely to gradually drift away
> equatorwards and melt, while being continuously replenished by newly
> formed ice at the poles. This indicates that the two crucial numbers to
> compare would be the rate at which new ice forms vs. the velocity at
> which it gets carried away. Can one speculate about the magnitude and
> flow pattern of near-surface ocean circulation on an all-water (but
> otherwise more or less Earth-like) planet? With a deep and even sea
> floor, and in the absence of continental flow barriers, I'd expect them
> to be rather smooth and uniform, but I'm unsure as to how this could be
> determined more accurately.
>
> Jens.

As far as I know, an all-water planet would have HUGE circum-planetary
currents.

Would they be enough to spin the ice cap around and force it from leaving
the polar zone? Perhaps. I don't know.

[Tim Little]

On 2012-09-29, Thomas Koenig <tko...@netcologne.de> wrote:
> Assume a 60 mile ice sheet and a similar heat flux as the earth
> (0.043 W/m^2), the temperature at the bottom of the ice sheet would
> be approx 2900 K hotter than on the top. This is not possible, you
> would get water vapor.

Well, you get "fluid" -- way beyond the critical point in both
temperature and pressure. I wouldn't call it "vapour" due to the fact
that it would be both denser and more viscous than liquid water at
more familiar pressures. Obviously I do agree that you won't get an
ice sheet that thick.

> Two to five miles might be possible - 90 to 230 K temperature increase.

Well the lower end of that range, at least. An extra 230 K would
require 4 GPa pressure if starting from near 270 K. Even 90 K needs
2.2 GPa, which is definitely on the high side (and into ice VII).


--
Tim

[Tim Little]

On 2012-09-29, Sea Wasp (Ryk E. Spoor) <sea...@sgeinc.invalid.com> wrote:
> Hmm. Is Ice VI more or less dense than liquid water at that pressure?

All the other ices on the solid/fluid boundary are denser.


--
Tim

[Greg Goss]

thr...@sheol.org (Wayne Throop) wrote:

>: JRStern <JRS...@foobar.invalid>
>: What if we borrowed the charge suppressor from Ringworld and cut a 100
>: mile deep trench in the Earth's ocean, a couple of miles wide. That's
>: right through the current crust, and it would be hot on both sides, to
>: begin. Would the crust in effect "heal", even with that trench still
>: open,

...

>
>You can't really carve kilometers-deep features into rock.
>It isn't strong enough in 1g. So the excess weight outside the
>trenched out area will deform the rock (and/or magma) until the
>feature is shallow enough to hold its shape. And given that the
>floor of the trench is magma, and has very little strength, that'd
>be pretty shallow.

Niven's always had a fascination for "how can I put small pockets of
habitability onto an otherwise hostile planet". Most of his "Known
Space" planets have some facets of this.

In the case of Canyon, I think that the ditch was three or five miles
deep, not 100. So the rock WAS able to sustain its shave as the
entire planet's near-vacuum atmosphere all flowed into that one ditch,
leaving the rest of the planet with even nearer vacuum.
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.

[Greg Goss]

JRStern <JRS...@foobar.invalid> wrote:

>I suppose some advanced civilization (of dolphins? er no, better let
>whoever have gills ... or maybe not, as follows) might build a super
>water world like that, if there would be any interesting point in it.
>Which maybe not, if it's all going to be ice VI below sixty miles or
>so. Unless you like ice.

One of the stories accepted by Ben Baen's Universe (and eventually,
oddly, published in a Grantville Gazette) featured gene-edited
dolphins given gills and (better?) speech and inserted under the ice
of Europa, as part of saving bits of a collapsing ecology on Earth.
The story is a vignette set some considerable time afte that point.

[Greg Goss]

It would, of course, be distorted by Coriolis "forces". On our
planet, the Japan Current and the Gulf Stream start at the western end
of their ocean and travel northeast. (I don't know the southern
currents as well -- why does the Humbolt run the wrong direction? Do
any of the southern currents have this nice clean southeastern flow?)

So would the floating ice cap be rotating?

[Greg Goss]

ctbi...@earthlink.net (Charles Bishop) wrote:

>That's the part I was wondering about, whether geologic forces would
>eventually "even out" the surface with bumps some percentage of the radius
>of the planet. Would you expect higher mountains on a smaller, thus lower
>gravity, planet? Much like the much larger mountains on Mars. Though this
>is helped by limited erosion, isn't it?

When I was a kid, my older brother had a kid's science book. It
claimed that because of Earth's active geology, other planets wouldn't
have mountains to compare. It stated outright that Mars would have no
mountains worth looking at.

I wish that book were still around so we could point and laugh.

[John Park]

"nu...@bid.nes" (alie...@gmail.com) writes:
> On Sep 26, 8:58=A0pm, "Sea Wasp (Ryk E. Spoor)"
> <seaw...@sgeinc.invalid.com> wrote:
>> On 9/26/12 10:45 PM, n...@bid.nes wrote:
>>
>> > =A0 =A0OK, so why are you concerned with the high-frequency dielectric
>> > properties of exotic benthic ices?
>>
>> =A0 =A0 =A0 =A0 Looking for cool stuff to exploit -- will natural process=
> es cause it to
>> build up charge and electrocute everything above it? Will it transmit
>> radio waves naturally? I have no idea what the stuff does, but since the
>> characteristic of the ice was mentioned in my references I figured I'd
>> ask to see if there were some likely (or not so likely but believable)
>> consequences of those ices' characteristics.
>
> I got nothing for Debye relaxation, but did you know that water ices
> are proton conductors and can be magnetized?
>
> From this paper:
>
> http://physics.nd.edu/assets/29206/gower_christina_monte_carlo_simulation.p=
> df
>
> "Ice VI and Ice VII are known as the self-clathrate forms because
> their structure is composed of interpenetrating lattices with
> tetrahedral bonds." (No other ices have this characteristic.)
>
> and goes on to discuss modeling their magnetizability.
>
> Suppose there's sufficient irregularly-distributed stuff [element,
> compound, whatever] on your world to dope benthic ice at a particular
> stage in transition between VI and VII so that it becomes strongly
> ferromagnetic (maybe by linking the disordered separate latices so all
> the proton spins can align?), strongly enough to produce a noticeable
> (/usable) field wherever your drama occurs; surface or the deeps. You
> would probably get multiple magnetic poles. It occurs to me that
> quakes would strongly alter the magnetic field by moving the critical
> pressure up or down (or sideways) through ices with the proper dopant
> concentration, making navigation more "interesting" for all involved.
> You could get auroras at all latitudes, moving with the field
> changes...
>
> What to use as a dopant? I don't know. Doc Smith got away with
> claiming that a little Rhenium made a super-strong alloy (Leybyrdite)
> at least partly because nobody could gather enough Rhenium to call BS
> on him. Pick something fairly exotic.
>
> Oh, look:
>
> http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust
>
> No wonder Doc used Rhenium. ;>)
>

Hmm. Ferromagnetic ice. Not sure I should be as startled as I am. Do they
say anything about the temperature range of the ferro. phase?


--John Park

---------------
Janus, a novel
http://chizinepub.com/books/janus.php

[Paul Colquhoun]

On Sun, 30 Sep 2012 02:30:14 -0600, Greg Goss <go...@gossg.org> wrote:
| Jens Kleimann <yatterin...@web.de> wrote:
|
|>On 28.09.2012 11:05, Paul Colquhoun wrote:
|
|>> Given the cold conditions, wouldn't there be a general surface current
|>> towards the poles, from all directions, where the water would cool and
|>> sink, to then flow towards the equator and resurface there.
|>
|>You mean something like the marine version of a Hadley cell? Sounds reasonable. This would then act to stabilize a floating polar cap. And Coriolis forces, if of any importance at all, will tend to zero near the poles. So there's hope that an ice cap, once formed, can hope to stay there for quite some time. Nice!
|
| It would, of course, be distorted by Coriolis "forces". On our
| planet, the Japan Current and the Gulf Stream start at the western end
| of their ocean and travel northeast. (I don't know the southern
| currents as well -- why does the Humbolt run the wrong direction? Do
| any of the southern currents have this nice clean southeastern flow?)
|
| So would the floating ice cap be rotating?

Actually, that's another thing. Would the surface of a deep-ocean water
world rotate in sync, like Earth does, or have different day lengths by
latitude, like the Sun and the gas giants?

Maybe there will be enough friction with the core to damp it out, but I
thing the north-south flows of convection currents would have some
effect as they move masses of water closer/further from the axis of
rotation. Conservation of angular momentum would seem to require it.

There may even be variation in "day length" by depth. Assuming you can
still see any variation in light intensity.


--
Reverend Paul Colquhoun, ULC. http://andor.dropbear.id.au/~paulcol
Asking for technical help in newsgroups? Read this first:
http://catb.org/~esr/faqs/smart-questions.html#intro

[Thomas Koenig]

Looks like somebody has looked at this in much more detail
than I did, which is not really surprising.

I did a quick search and found an interesting article:

The Interior Dynamics of Water Planets, Roger Fu, Richard J. OConnell,
Dimitar D. Sasselov, http://arxiv.org/pdf/1001.2890v1 . They were
looking at Super-Earths from 2 to 10 Earth masses, with 25% and
50% of water. Maybe you can ask the authors to run a simulation
for you :-)

Solid-state convection can play a big role, so the ice will not
be quite as static as I thought.

[Sea Wasp (Ryk E. Spoor)]

On 9/30/12 7:35 AM, Thomas Koenig wrote:
> Looks like somebody has looked at this in much more detail
> than I did, which is not really surprising.
>
> I did a quick search and found an interesting article:
>
> The Interior Dynamics of Water Planets, Roger Fu, Richard J. OConnell,
> Dimitar D. Sasselov, http://arxiv.org/pdf/1001.2890v1 . They were
> looking at Super-Earths from 2 to 10 Earth masses, with 25% and
> 50% of water. Maybe you can ask the authors to run a simulation
> for you :-)

Oh, excellent. This may be useful indeed!

[JRStern]

On Sun, 30 Sep 2012 09:03:40 -0400, "Sea Wasp (Ryk E. Spoor)"
<sea...@sgeinc.invalid.com> wrote:

>On 9/30/12 7:35 AM, Thomas Koenig wrote:
>> Looks like somebody has looked at this in much more detail
>> than I did, which is not really surprising.
>>
>> I did a quick search and found an interesting article:
>>
>> The Interior Dynamics of Water Planets, Roger Fu, Richard J. OConnell,
>> Dimitar D. Sasselov, http://arxiv.org/pdf/1001.2890v1 . They were
>> looking at Super-Earths from 2 to 10 Earth masses, with 25% and
>> 50% of water. Maybe you can ask the authors to run a simulation
>> for you :-)
>
> Oh, excellent. This may be useful indeed!

Well, apparently they are big on ice mantles, the temperature they
posit is up to 1200c degrees IN THE ICE, but the pressure overcomes
internal and external heat sources - assuming anything on the surface
resembling habitable. They consider planets up to 50% water (and 2x
to 5x total Earth mass), that's a *lot* more water than Earth. They
consider pressure melt effects, but seem to punt them out to further
research. They consider plumes of melt over a (volcanic) heat source.

(Even a 100 mile deep ocean on Earth would still be just about 5% of
the mass of the planet, right?)

Something with that much water, light elements, would seem to have
rather less radioactives per planetary mass than Earth, and replacing
most rock with ice would cool it faster ... unless somehow it managed
to increase the concentration of the radioactives present.

They don't seem to mention any exotic electrical effects from the
exotic ices.

J.

[JRStern]

I believe the ditch was deeper, magma filled it back up (encasing
slaver fields with Kzin?).

J.

[Mark Zenier]

In article <13489...@sheol.org>, Wayne Throop <thr...@sheol.org> wrote:
>: JRStern <JRS...@foobar.invalid>
>: If much of the iron is in the core because it was more dense, aren't
>: there more radioactives there too?
>
>No. Much like, "if nitrogen is less dense than oxygen, why aren't
>we living in a 100% oxygen environment, with all the nitrogen far
>above our heads?". And why don't people in valleys suffocate on the
>carbon dioxide, etc.

They do. It's not uncommon, in volcanicly active areas in East Africa,
for people to walk into a hollow and not walk out . (And there's also
that carbonated lake accidentally popping its cork, with the gas cloud
flowing down the valley smothering everybody.)

That's one problem I see with deep oceans. If the oxygen transfer isn't
good enough, they'll be largely anoxic. Even with transfer, there's
a reason that most of the large marine predators are air breathers.
With the (as I remember) 20 to 1 advantage for lungs over gills in
oxygen supply and transfer, even really bizarre feeding strategys like
the elephant seal and the sperm whale can work.

Mark Zenier mze...@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)

[Jens Kleimann]

On 30.09.2012 01:11, Aleksandar Kuktin wrote:
> As far as I know, an all-water planet would have HUGE circum-planetary
> currents.

But HOW do you know this? Just by analogy from Venus' atmosphere?

> Would they be enough to spin the ice cap around and force it from leaving
> the polar zone? Perhaps. I don't know.

Such currents, if present and strong enough, could potentially spin the cap, but how does spinning help to keep it in place?

Jens.
--
Remove '_nospam' for actual email address.

[David DeLaney]

Jens Kleimann <yatterin...@web.de> wrote:
>On 30.09.2012 01:11, Aleksandar Kuktin wrote:
>> As far as I know, an all-water planet would have HUGE circum-planetary
>> currents.
>
>But HOW do you know this? Just by analogy from Venus' atmosphere?

... if there's no landmasses breaking them up, they just keep building slowly,
until they run up against friction with the bottom?

>> Would they be enough to spin the ice cap around and force it from leaving
>> the polar zone? Perhaps. I don't know.
>
>Such currents, if present and strong enough, could potentially spin the cap,
> but how does spinning help to keep it in place?

...conservation of angular momentum?

Planets have to obey the basics of physics too.

Dave, unless your novel specifies that they don't, of course
--
\/David DeLaney posting from d...@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

[Wayne Throop]

:::As far as I know, an all-water planet woul dhave HUGE circum-planetary
::: currents. Would they be enough to spin the ice cap around and force it

::: from leaving the polar zone? Perhaps. I don't know.

:: Such currents, if present and strong enough, could potentially spin
:: the cap, but how does spinning help to keep it in place?

: d...@gatekeeper.vic.com (David DeLaney)
: ...conservation of angular momentum?

: Planets have to obey the basics of physics too.

OK. Their momentum is conserved.
But how does that help keep them over the pole?
Sure, the coriolis forces associated with the additional spin
would do something, but not sure iti'd confine the ice at the pole.
I'd think the skew added to the circum-polar currents by
any thermally driven circulation would do a better job of that.
Rather than pure curcumpolarosity, I mean.

[Greg Goss]

Jens Kleimann <yatterin...@web.de> wrote:

>On 30.09.2012 01:11, Aleksandar Kuktin wrote:
>> As far as I know, an all-water planet would have HUGE circum-planetary
>> currents.
>
>But HOW do you know this? Just by analogy from Venus' atmosphere?
>
>> Would they be enough to spin the ice cap around and force it from leaving
>> the polar zone? Perhaps. I don't know.
>
>Such currents, if present and strong enough, could potentially spin the cap, but how does spinning help to keep it in place?

Elsewhere in the thread there was a discussion of diagonal currents
rising at the equator, traveling NE and SE along the surface then
dropping near the pole and returning at depth (like the Gulf Stream or
Japan Current). Such currents would push floating stuff to the poles
and keep it there.

I'm not sure what coriolis forces there would be on a large rotating
continent just slightly off center from the pole, if any. Someone
with better mathematical intuition would have to jump in.

[David DeLaney]

Wayne Throop <thr...@sheol.org> wrote:
>:::As far as I know, an all-water planet woul dhave HUGE circum-planetary
>::: currents. Would they be enough to spin the ice cap around and force it
>::: from leaving the polar zone? Perhaps. I don't know.
>
>:: Such currents, if present and strong enough, could potentially spin
>:: the cap, but how does spinning help to keep it in place?
>
>: d...@gatekeeper.vic.com (David DeLaney)
>: ...conservation of angular momentum?
>: Planets have to obey the basics of physics too.
>
>OK. Their momentum is conserved.

ANGULAR momentum. Which points perpendicular to the plane of the spin.

>But how does that help keep them over the pole?

Moving the ice around the curvature of the earth this way or that would change
the direction the J vector was pointing (straight up or down from the middle of
the spin, as an approx.). This takes force. Same reason your gyroscope works,
or your bicycle wheels resist turning sideways when they're spinning.

Dave

[Wayne Throop]

:: OK. Their momentum is conserved.
:: But how does that help keep them over the pole?

: d...@gatekeeper.vic.com (David DeLaney)
: ANGULAR momentum. Which points perpendicular to the plane of the spin.

Sounds like circular impetus, so far.

: Moving the ice around the curvature of the earth this way or that

: would change the direction the J vector was pointing (straight up or
: down from the middle of the spin, as an approx.). This takes force.
: Same reason your gyroscope works, or your bicycle wheels resist
: turning sideways when they're spinning.

Ah. But now it doesn't. However, I *seriously* doubt you can treat a
polar ice pack as a rigid object, so you's have to be doing the analysis
from the pov of a point-floe (and-or flow) at the edge of the pack.
And from that pov, the torque required to move the spin access is not
as formidable. Or so it seems to me.

I might have said "what happens if you consider a gyroscope as a cloud
of separate particles", but luckily I noted to myself that the ice is
sitting on the equoitential surface, and so net centrifugal tendencies
aren't really there...

We're just bobbing along in our barrel
Some of us may tip right over the edge
But there's one thing really mystifying
Got me laughing, now it's got me crying
All my life I will be death defying
'Til I know

I wonder wonder why the wonder falls
I wonder why the wonder falls on me
I wonder wonder why the wonder falls
With everything I touch and hear and see

--- Wonderfalls

[Greg Goss]

thr...@sheol.org (Wayne Throop) wrote:

>Ah. But now it doesn't. However, I *seriously* doubt you can treat a
>polar ice pack as a rigid object, so you's have to be doing the analysis
>from the pov of a point-floe (and-or flow) at the edge of the pack.
>And from that pov, the torque required to move the spin access is not
>as formidable. Or so it seems to me.
>
>I might have said "what happens if you consider a gyroscope as a cloud
>of separate particles", but luckily I noted to myself that the ice is
>sitting on the equoitential surface, and so net centrifugal tendencies
>aren't really there...

I think we disagree about this bit, even before we start talking about
coriolis forces.

I note that significant (by human scale) chunks of Antarctica are "ice
sheets" that are monolithic and float. If it gets too warm, some of
them get too thin, and break off -- I vaguely remember news items of
Rhode-Island-sized chunks drifting away. But so long as the cold
holds, the sheet is pretty much monolithic.

On a water planet, such ice sheets would not just be a periphery
issue, but the ice cap as a whole. So long as we get close enough to
the pole to overcome warming globe issues (grin) it should be thick
enough to overcome the brittleness that would reduce it to a mass of
separate floes.

[alie...@gmail.com]

On Oct 2, 10:22 am, d...@gatekeeper.vic.com (David DeLaney) wrote:

> Wayne Throop <thro...@sheol.org> wrote:
> >:::As far as I know, an all-water planet woul dhave HUGE circum-planetary
> >::: currents. Would they be enough to spin the ice cap around and force it
> >::: from leaving the polar zone?  Perhaps.  I don't know.
>
> >:: Such currents, if present and strong enough, could potentially spin
> >:: the cap, but how does spinning help to keep it in place?
>
> >: d...@gatekeeper.vic.com (David DeLaney)
> >: ...conservation of angular momentum?
> >: Planets have to obey the basics of physics too.
>
> >OK.  Their momentum is conserved.
>
> ANGULAR momentum. Which points perpendicular to the plane of the spin.
>
> >But how does that help keep them over the pole?
>
> Moving the ice around the curvature of the earth this way or that would change
> the direction the J vector was pointing (straight up or down from the middle of
> the spin, as an approx.). This takes force. Same reason your gyroscope works,
> or your bicycle wheels resist turning sideways when they're spinning.

Only if the spin axis passes through the center of mass.

If new ice formation is asymmetrical around the axis (due to more
night-side clouds, say), the center of mass moves; there's your force.

Ice isn't particularly rigid in large pieces. The lower the
latitude, the larger the force on a given element of ice. Bergs large
and small will calve (calf?) off, each removing some of the off-axis
angular momentum vector component, stabilizing the larger mass.

(According to the vector diagram in my head anyway.)


Mark L. Fergerson

[david.sh...@ymail.com]

On Oct 2, 3:02 pm, Greg Goss <go...@gossg.org> wrote:
> I note that significant (by human scale) chunks of Antarctica are "ice
> sheets" that are monolithic and float.  If it gets too warm, some of
> them get too thin, and break off -- I vaguely remember news items of
> Rhode-Island-sized chunks drifting away.  But so long as the cold
> holds, the sheet is pretty much monolithic.
>
> On a water planet, such ice sheets would not just be a periphery
> issue, but the ice cap as a whole.

Why do you think that?
The ice shelves of Antarctica are fed by glaciers.
The Arctic has pack ice, that wikipedia thinks is maybe
3 to 4 meters thick, and does not act as a monolithic body.

[John Park]

So maybe an aerobic ecology near the surface (suitable values of "near")
and one of more anaerobic ecologies based on volcanic vents or the
equivalent. And each sees nothing but desert elsewhere. Until someone
invents a way to take their ecosphere with them (AKA a submarine)...

----John Park