APOD: All the Water on Planet Earth (2016 Sep 11)

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Expand view Topic review: APOD: All the Water on Planet Earth (2016 Sep 11)

A scenario & a big question

by longtry » Sun Nov 03, 2019 11:02 am

I have a hypothetical scenario. Supposed that in some magical way all the water on Earth (minus that in living things - biosphere) collects into that ball. What will happen next?

But my main question is: is this forum, particularly this topic, the place where I should ask this kind of query? If not, where would be the most appropriate place on the internet?

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by chuckster » Tue Sep 13, 2016 12:03 am

You may as well bundle the whole crust beyond the depth man has ever ventured and roll it into a ball,
I think gravity did that already, about 4 billion years ago. It's what the water's sitting on.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by BMAONE23 » Mon Sep 12, 2016 5:12 pm

It was an interesting read though.
The current estimated population of 7.45 Billion would have approx 40sq' each or 5' x 8' on Hawaii
Who wants the Beach Cubicles??

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by rstevenson » Mon Sep 12, 2016 2:09 pm

BMAONE23 wrote:
ta152h0 wrote:how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?
You could also take all the human inhabitants and relocate them to the Hawaiian islands with some room to spare
This concept was the starting point for a 1968 science fiction novel called Stand on Zanzibar, by John Brunner. From its Wikipedia article...
The primary engine of the novel's story is overpopulation and its projected consequences, and the title refers to an early twentieth-century claim that the world's population could fit onto the Isle of Wight – which has an area of 381 square kilometres (147 sq mi) – if they were all standing upright. Brunner remarked that the growing world population now required a larger island; the 3.5 billion people living in 1968 could stand together on the Isle of Man (area 572 square kilometres (221 sq mi)), while the 7 billion people who he (correctly) projected would be alive in 2010 would need to stand on Zanzibar (area 1,554 square kilometres (600 sq mi)). Throughout the book, the image of the entire human race standing shoulder-to-shoulder on a small island is a metaphor for a crowded world.
As I recall, at the end of the book the outermost people were likely to be ankle deep in the sea, an image that has stuck with me ever since.

Rob

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Chris Peterson » Mon Sep 12, 2016 1:49 pm

Guest wrote:It is just plain dumbed down anti-science to entertain the silly notion of the Earth's water bundled into a little ball. You may as well bundle the whole crust beyond the depth man has ever ventured and roll it into a ball, it is about as arbitrary, useful and misleading a comparison!
Your point entirely escapes me. But I do recognize that you're missing the point of this APOD. Badly.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Chris Peterson » Mon Sep 12, 2016 1:47 pm

Nitpicker wrote:
Chris Peterson wrote:
ta152h0 wrote:how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?
All of humanity would fit in a volume of about one cubic kilometer. Smaller than a pixel in this image.

The internal temperature from metabolic heat would be high enough to initiate thermonuclear fusion.
I agree on the size, but the core metabolic heat would dissipate rather quickly, as everyone was crushed and/or suffocated to death. Lovely thought.
Of course, such a thing couldn't be constructed. It's just an illustration of the temperature that would (theoretically) result given packing in a bunch of 100 watt emitters (humans) in a confined space.
But how much volume does every living thing on Earth take up?
The usually quoted value for the volume of the biosphere is a sphere approximately 20 km in diameter.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by neufer » Mon Sep 12, 2016 12:00 pm

RocketRon wrote:
What may be more interesting to know is what average depth of water would occur everywhere if the entire surface of earth was quite flat and covered with all the water calculated here.
Just under 3 kilometers...or slightly less than the current average ocean depth.
RocketRon wrote:
As a GAS, the atmosphere (on Earth) has more depth, considerably more....
As a GAS, half the atmosphere (on Earth) lies below 5.5 kilometers.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by DavidLeodis » Mon Sep 12, 2016 11:52 am

This link (brought up through the "featured illustration" link) brings up among other things an even more informative illustration of Earth's surface water distribution. http://water.usgs.gov/edu/gallery/globa ... olume.html.

The "If you put a (big) pin to the largest bubble showing total water, the resulting flow would cover the contiguous United States (lower 48 states) to a depth of about 107 miles" information through the link is quite staggering (well it is to me :wink: ).

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by starbrush » Mon Sep 12, 2016 11:43 am

It's a fine and poignant image, and I'm all for describing phenomena, processes and quantities in different ways, because these can then give access to fresh ways of looking at other, er, spheres! Otherwise, why pay any attention to a bored Swiss patent clerk chasing torch beams?

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by bmander » Mon Sep 12, 2016 11:08 am

Puts things in perspective, doesn't it?

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by geckzilla » Mon Sep 12, 2016 7:38 am

Guest wrote:It is just plain dumbed down anti-science to entertain the silly notion of the Earth's water bundled into a little ball. You may as well bundle the whole crust beyond the depth man has ever ventured and roll it into a ball, it is about as arbitrary, useful and misleading a comparison!
Come on. It's a useful demonstration that puts our precious resources into perspective. From our viewpoint the Earth seems vast and immutable, but in reality it is finite and we can easily trash it up.

Whatever point you want to make is not the point this picture conveys.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by RocketRon » Mon Sep 12, 2016 6:38 am

What may be more interesting to know is what average depth of water would occur everywhere if the entire surface of earth was quite flat and covered with all the water calculated here.

As a GAS, the atmosphere (on Earth) has more depth, considerably more....

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Guest » Mon Sep 12, 2016 5:57 am

Doubling the amount of water would do that. That would increase the diameter of the sphere by 25%. Barely noticeable.
Exactly and that is my point!!
If we take the highest estimates for mantle water (which isn't strictly H2O), it would approximately double the diameter of the sphere. Still not a "water world".
Exactly! And again you make my point!

Talk about a way to totally miss the point! Our terrestrial world is blessed by liquid H2O. Drowning all the continents with water, then bundling all that into a sphere 25% larger (As you say) demonstrate what a stupid but sensational comparison this APOD is.

As far as terrestrial worlds go the Earth is as close to a "Water world" as we will probably ever find, that is capable of supporting terrestrial life - and I say this - because it demonstrably so! A life supporting "Water world" requires a core and a crust of a large enough diameter to generate an atmosphere protecting magnetic field. If you were going to build one, you would have to start here and then add water. And by necessity the ratio between the sizes of the two spheres will be roughly as you depict!

There have been times in the past when the whole surface of the earth was beneath frozen H2O.

It is just plain dumbed down anti-science to entertain the silly notion of the Earth's water bundled into a little ball. You may as well bundle the whole crust beyond the depth man has ever ventured and roll it into a ball, it is about as arbitrary, useful and misleading a comparison!

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by geckzilla » Mon Sep 12, 2016 5:36 am

Nitpicker wrote:
Chris Peterson wrote:
ta152h0 wrote:how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?
All of humanity would fit in a volume of about one cubic kilometer. Smaller than a pixel in this image.

The internal temperature from metabolic heat would be high enough to initiate thermonuclear fusion.
I agree on the size, but the core metabolic heat would dissipate rather quickly, as everyone was crushed and/or suffocated to death. Lovely thought.

But how much volume does every living thing on Earth take up?
Undoubtedly some of the volume of water in this image is actually a living creature. How much extra water not included in the calculation is locked away in living processes?

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by BMAONE23 » Mon Sep 12, 2016 5:24 am

ta152h0 wrote:how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?
You could also take all the human inhabitants and relocate them to the Hawaiian islands with some room to spare

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Nitpicker » Mon Sep 12, 2016 4:49 am

Chris Peterson wrote:
ta152h0 wrote:how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?
All of humanity would fit in a volume of about one cubic kilometer. Smaller than a pixel in this image.

The internal temperature from metabolic heat would be high enough to initiate thermonuclear fusion.
I agree on the size, but the core metabolic heat would dissipate rather quickly, as everyone was crushed and/or suffocated to death. Lovely thought.

But how much volume does every living thing on Earth take up?

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Chris Peterson » Mon Sep 12, 2016 3:48 am

ta152h0 wrote:how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?
All of humanity would fit in a volume of about one cubic kilometer. Smaller than a pixel in this image.

The internal temperature from metabolic heat would be high enough to initiate thermonuclear fusion.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by ta152h0 » Mon Sep 12, 2016 3:31 am

how big would this sphere be if you take the volume of every inhabitant of the Earth and create a sphere representing this volume ?

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by neufer » Mon Sep 12, 2016 2:24 am

viktor@viktortec.com wrote:
Excellent picture! BTW, it would be also interesting to show a second ball in the picture showing the earth atmosphere in water equivalent....scary!
The average depth of the ocean is a couple of kilometers whereas the average depth of atmospheric water is a couple of precipitable centimeters... a factor of ~100,000 in volume or of ~45 in spherical radius.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by viktor@viktortec.com » Mon Sep 12, 2016 1:36 am

Excellent picture! BTW, it would be also interesting to show a second ball in the picture showing the earth atmosphere in water equivalent....scary!
Cheers, Viktor

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Nitpicker » Mon Sep 12, 2016 12:25 am

A comment slightly modified from one I made in an earlier APOD featuring this image:

There is a large amount of water on Earth, in relation to the habitable volume of Earth. What the APOD really shows is that the total volume of Earth is so much (~600 times) bigger than the habitable volume of Earth. If we make the simple assumption that all of the Earth's water (1386 million km3) is habitable and make the further (even simpler) assumption that the lowest 1 km of atmosphere above the whole Earth's surface (510 million km3) is habitable, then (ignoring the volume of any subterranean habitable space, which I've just lumped in with the somewhat arbitrary habitable atmospheric volume), all of the Earth's water represents 73% of the habitable volume of Earth. The remaining volume of Earth is not habitable, but I am glad it is there, as its vast mass gives we surface dwellers an acceleration due to gravity of about 10 metres per second per second, of which I, for one, am rather fond.

The fact is that sea levels are predicted to rise in the coming centuries, by amounts expected to cause all sorts of problems for humanity. This appears to be at odds with the notion that there isn't that much water on Earth. Change is good for life in general, but not necessarily for human life in this particular instance. If one considers only the habitable volume of Earth, it could be considered to be a "water world" of sorts.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by khh » Sun Sep 11, 2016 11:34 pm

Don't be fooled by the small size. You could actually down in that much water.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by APODFORIST » Sun Sep 11, 2016 9:31 pm

It would be also interesting to visualize the earth crust as a sphere in comparison to the fluid inner part an the hard earth's core.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by neufer » Sun Sep 11, 2016 6:30 pm

Chris Peterson wrote:
Scott W Bennett wrote:
How much bigger would that stupid sphere have been if all the continents were covered?
Doubling the amount of water would do that.
That would increase the diameter of the sphere by 25%.
  • If the object is to cover every mountain (i.e., Everest)
    then one would have to quadruple the amount of water.

    That would increase the diameter of the sphere by ~60%.

Re: APOD: All the Water on Planet Earth (2016 Sep 11)

by Ann » Sun Sep 11, 2016 6:01 pm

Thanks for your posts, Chris and Rob.
Rocky and icy planetesimals and the snow line.
Probable source: science/sciencemag.org.
Here you can see the reason why the Earth is not a water world. The Earth formed out of smaller rocky bodies on the warm side of the so called snow line in the early solar system.

In space, water can exist only as a gas, water vapor, or as a solid, ice. The Earth was formed in the part of the solar system where all the water was in the form of water vapor. The building blocks of the Earth were rocky boulders, not blocks of ice. But on the cold side of the snow line, blocks of ice and ice-covered boulders were indeed floating around, and they collided with each other and formed the icy moons and ice giant planets of the outer solar system.

The Earth was formed with very little water. In a way you can say that the Earth has "too much water" considering where it was formed, and that it must have received a generous helping of water from space, maybe delivered by ice-rich asteroids.

The fact that Earth has a lot of liquid water even though it was formed on the ice-less warm side of the snow line in the primordial solar system suggests that other Earth-like planets in other solar systems should perhaps also form on the warm side of the snow line and have water delivered to them afterwards.

Ann

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