Why is it so hard to make a (big) diamond?

[grondilu]

This is a question that naggers me sometimes.  It's about diamonds.  Ever since I heard about Neil Stephenson's book "The diamond age" (Haven't read it yet, though), I keep wondering why we are not capable of making diamonds in a industrial way.

Some methods for making diamonds exist already.  Check out wikipedia if you don't know about them.

So why is the biggest known diamond on earth still a natural one??  What's so hard?

Also:  what about using a brute force method?   I mean, a diamond is made from carbon with pressures around 6GPa.  Fine, can't this be done without using explosives or stuff like that?  I mean, with a purely mechanical device?

6 GPa.  That's 6 GigaNewton per square meter.  That's about 600e6 kg weighting on the same surface.  That's 600 Kt  (Kilo metric ton).   One ton is a cubic meter of water.    So 6 GPa is the pressure at the bottom of a 600 kilometers deep ocean.  That's deep.

But I don't need a 1 meter-sized diamond.  I'd be happy with a 10cm one or so.  That's one hundred times smaller a surface than a square meter.  So I just need a 6 Km deep ocean, providing that I can manage to have a one square meter water column weight on a square decimeter one.

Hell I can reduce the height of the thing by an hundred factor if I use a wilder column.  So, a ten-meter per ten-meter section column need to be 6 Km / 100 = 60m height.

So here is my question:  isn't it possible to build a 10m x 10m x 60m pool (or a 11.27m radius spherical water tank) and have it weight on a 10cm x 10cm area?

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[greyhawk]

I don't think anyone tried. There are no industrial applications to use big diamonds for that I'm aware of.

[JohnBigheart]

Synthetic diamonds can be manufactured using the HPHT  (High Pressure High Temperature process):
http://en.wikipedia.org/wiki/HPHT_diamond#High_pressure.2C_high_temperature

Because of the surface to volume ratio the HPHT presses don't scale well with size. Eventually the cost of the press will be more then the cost of the diamond produced.

[ElectricMucus]

The "Diamonds" in The Diamond Age are more in the realm of carbon quasi-crystals. The way to go there is research into grapheme and nano-tubes, a much more interesting concept.
From what I can tell, the difficulty is heat or the right amount of heat and pressure to enable the self-assimilation process of molecular structures.

Anyway I think we are far away from ever building a matter compiler, at least if the current scientific consensus in physics remains the way it is.

If you just wanna produce diamonds, there is no real limit to it's size except building a sufficiently large pressure chamber which is expensive to make (failure rate goes up the larger you make it)

[Phinnaeus Gage]

The "Diamonds" in The Diamond Age are more in the realm of carbon quasi-crystals. The way to go there is research into grapheme and nano-tubes, a much more interesting concept.
From what I can tell, the difficulty is heat or the right amount of heat and pressure to enable the self-assimilation process of molecular structures.

Anyway I think we are far away from ever building a matter compiler, at least if the current scientific consensus in physics remains the way it is.

If you just wanna produce diamonds, there is no real limit to it's size except building a sufficiently large pressure chamber which is expensive to make (failure rate goes up the larger you make it)

Solved!: https://bitcointalk.org/index.php?topic=124443.0

[Stephen Gornick]

Because of the surface to volume ratio the HPHT presses don't scale well with size. Eventually the cost of the press will be more then the cost of the diamond produced.

And it is kind of like the question about why doesn't someone do a 51% attack to double spend bitcoins?   Because once you do that, the coins you got from double spending are no longer worth anything because you just destroyed the entire reason they had value.

[grondilu]

And it is kind of like the question about why doesn't someone do a 51% attack to double spend bitcoins?   Because once you do that, the coins you got from double spending are no longer worth anything because you just destroyed the entire reason they had value.

Diamonds don't have value just because they are scarce.

Imagine you actually could make some as big as you want, and at will.  Would you refrain yourself from doing it?  I bet you wouldn't.  You'd make some because diamonds are cool and pretty.

Humans love to make things, regardless of whether it has value or not.  It just has to be fun, cool, or beautiful.  And because sometimes the value is not in the product, it's in the act of making it.

If someone could figure out a way of making a car-sized diamond, I'm pretty sure someone would actually do it.

[MPOE-PR]

Hell I can reduce the height of the thing by an hundred factor if I use a wilder column.  So, a ten-meter per ten-meter section column need to be 6 Km / 100 = 60m height.

This is not quite how pressure works. No matter how thin/thick your column is, the pressure at its bottom is still just a function of the height.

[grondilu]

Hell I can reduce the height of the thing by an hundred factor if I use a wilder column.  So, a ten-meter per ten-meter section column need to be 6 Km / 100 = 60m height.

This is not quite how pressure works. No matter how thin/thick your column is, the pressure at its bottom is still just a function of the height.

The whole large column rests on a single very tight rod, with a 10cm x 10cm section.


Like this:
|                                |
|                                |
|                                |
|________    ________|
               |  |              
               |_|

But of course with a better shape (this one can't obviously support the weight)

[MrTeal]

Hell I can reduce the height of the thing by an hundred factor if I use a wilder column.  So, a ten-meter per ten-meter section column need to be 6 Km / 100 = 60m height.

This is not quite how pressure works. No matter how thin/thick your column is, the pressure at its bottom is still just a function of the height.

The whole large column rests on a single very tight rod, with a 10cm x 10cm section.


Like this:
|                                |
|                                |
|                                |
|________    ________|
               |  |              
               |_|

But of course with a better shape (this one can't obviously support the weight)

That's still not how pressure works. The water underneath the plate supports the plate as well. Your diamond would have the same pressure as if it were just sitting under 60m of water. Now, if you made a 10mx10mx60m container of water like you described on the surface, you could get those kinds of pressures.

Question: What material will you use for your anvil that will allow you to compress carbon to those pressures without deforming?

[grondilu]

Hell I can reduce the height of the thing by an hundred factor if I use a wilder column.  So, a ten-meter per ten-meter section column need to be 6 Km / 100 = 60m height.

This is not quite how pressure works. No matter how thin/thick your column is, the pressure at its bottom is still just a function of the height.

The whole large column rests on a single very tight rod, with a 10cm x 10cm section.


Like this:
|                                |
|                                |
|                                |
|________    ________|
               |  |              
               |_|

But of course with a better shape (this one can't obviously support the weight)

That's still not how pressure works. The water underneath the plate supports the plate as well. Your diamond would have the same pressure as if it were just sitting under 6km of water.

There is no water under the plate.  What I drew on the lower part is the steal rod.  But I guess I should have drawn this:

|                                |
|                                |
|                                |
|__________________|
               |  |              
               |_|

Notice the separation.

[MrTeal]

Hell I can reduce the height of the thing by an hundred factor if I use a wilder column.  So, a ten-meter per ten-meter section column need to be 6 Km / 100 = 60m height.

This is not quite how pressure works. No matter how thin/thick your column is, the pressure at its bottom is still just a function of the height.

The whole large column rests on a single very tight rod, with a 10cm x 10cm section.


Like this:
|                                |
|                                |
|                                |
|________    ________|
               |  |              
               |_|

But of course with a better shape (this one can't obviously support the weight)

That's still not how pressure works. The water underneath the plate supports the plate as well. Your diamond would have the same pressure as if it were just sitting under 6km of water.

There is no water under the plate.  What I drew on the lower part is the steal rod.  But I guess I should have drawn this:

|                                |
|                                |
|                                |
|__________________|
               |  |              
               |_|

Notice the separation.

So this structure is suspended in air?

[grondilu]

So this structure is suspended in air?

No.  It rests on the rod.


Possibly inside a fixed structure that limits its motion to a vertical movement, though.

[MrTeal]

So this structure is suspended in air?

No.  It rests on the rod.


Possibly inside a fixed structure that limits its motion to a vertical movement, though.

It rests on the rod, but is this basically a huge cup filled with water on the surface, all surrounded by air, or is the entire thing underwater?

[Gabi]

Do you realize that pressure depends only on the height of the water column right? Making it wider doesn't change anything

[grondilu]

Do you realize that pressure depends only on the height of the water column right?

Yes I do.  Please stop now.  I just use water to have a cheap large amount of mass.   Replace it in your mind by sand or stone bricks if you want.

[Gabi]

Then why use

|                                |
|                                |
|                                |
|__________________|
               |  |              
               |_|

if

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is the same?

[grondilu]

Then why use

|                                |
|                                |
|                                |
|__________________|
               |  |              
               |_|

if

| |
| |
| |
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|_|

is the same?

Because it is not the same.  In the first example all the water mass rests on the rod, and there is much more water mass.

We're just not talking about the same mechanical structure.  I'm talking about a rigid tank resting on a narrow rod.  You seem to be willing to talk about pressure on the bottom of a deep pool.

[grondilu]

So this structure is suspended in air?

No.  It rests on the rod.


Possibly inside a fixed structure that limits its motion to a vertical movement, though.

It rests on the rod, but is this basically a huge cup filled with water on the surface, all surrounded by air, or is the entire thing underwater?

It's just a water tank.

[MrTeal]

So this structure is suspended in air?

No.  It rests on the rod.


Possibly inside a fixed structure that limits its motion to a vertical movement, though.

It rests on the rod, but is this basically a huge cup filled with water on the surface, all surrounded by air, or is the entire thing underwater?

It's just a water tank.

Yes, then that should work. Out of curiosity, what materials will you build your 4"x4" rod out of that will support having 600,000,000kg on top of it?