Finding the Strongest Low-Density Material

[jhami]

What would be the strongest possible material that has a density under 10,000 g/cm^3?

 

[Vanadium 50]

A. "strongest" is vague. Tensile? Shear? Compressive?
B. Why is this science fiction?
C. Did you make any effort to find this out on your own?

 

[berkeman]

What would be the strongest possible material that has a density under 10,000 g/cm^3?

How is this different from the other thread that you started a few days ago?

https://www.physicsforums.com/threa...ength-allowed-by-physics.983579/#post-6291151

 

[DaveC426913]

Diamond has a density of a mere 3.5g/cm³, yet can withstand compressions up to 60GPa.

 

[jhami]

1. "Strongest", as in the best combination of Melting Point, Hardness, Yield Strength, Tensile Strength, Toughness, and Stiffness.
2, As I am asking how an infinitely advanced civilization would create this (only limited by the laws of physics)
3. I know that researchers are creating new and more strong materials every year (like this https://futurism.com/mit-unveils-new-material-thats-strongest-and-lightest-on-earth), but i want to know the upper limit to the strength of a material that is composed of baryonic matter (so not including neutronium, quark matter, etc.)

 

[jhami]

How is this different from the other thread that you started a few days ago?

https://www.physicsforums.com/threa...ength-allowed-by-physics.983579/#post-6291151

I was asking about an actuator, and now i am asking about a material

 

[jhami]

Diamond has a density of a mere 3.5g/cm³, yet can withstand compressions up to 60GPa.

Yes but diamond is not the upper limit to the strength of a material sevral other materials have been discovered which are harder like https://futurism.com/mit-unveils-new-material-thats-strongest-and-lightest-on-earth

 

[DaveC426913]

... how an infinitely advanced civilization would create this (only limited by the laws of physics)

Well that's the sticky bit isn't it?

A fabulously advanced civilization will have laws of physics that violate what we know today, so there's no real upper limit.

For all we know, they could have molecules that are strengthened through some sort of charge in ways we cannot begin to fathom. Heck, they could make stronger molecules by adding phantom atoms in the other seven dimensions of string theory.

That's your job as a science-fiction writer - to envision future technology the rest of us can't imagine.

 

[Vanadium 50]

1. "Strongest", as in the best combination of Melting Point, Hardness, Yield Strength, Tensile Strength, Toughness, and Stiffness.

That's even vaguer. Who is to say what "best" is? If you aren't willing to put in the effort to ask a clear question, how do you expect to get a clear answer?

 

[DaveC426913]

That's even vaguer. Who is to say what "best" is?

I'd say he is asking us to make some assumptions about that for the sake of story.

I think unpacking the word "best" would result in "most plausible in terms of an useful material to a fabulously advanced civilization."

 

[fresh_42]

I think we must not use the same standards in the science fiction section as in technical forums. Everybody knows it's Duranium.

 

[DaveC426913]

The OP must ask himself what every sci-fi writer must: how much detail do I need to put in?
Does it need to be scientifically accurate, or does it just need to be plausible?

I mean - it can't be accurate, since the first condition is that it is science fabulously far in advance of our own. Thus is is merely a matter of how far toward plausible is required?

Ultimately, the I think the best answer we can give the OP is: We can't tell you what the limits are for a civilization that advanced. That's up to you.

 

[DaveC426913]

Yes but diamond is not the upper limit to the strength of a material sevral other materials have been discovered which are harder like https://futurism.com/mit-unveils-new-material-thats-strongest-and-lightest-on-earth

That's actually showcasing strength-per-unit-density. i.e. density - and thus total mass - of the material is a constraining factor.

"...10 times stronger than steel, with only five percent of its density "

The OP grants a fabulously generous density limit for his material, meaning we're really just looking for absolute strength before we'll ever even have to consider density factoring in.

 

[member 656954]

The OP must ask himself what every sci-fi writer must: how much detail do I need to put in?
Does it need to be scientifically accurate, or does it just need to be plausible?

I second this sage observation by @DaveC426913 every time.

@jhami you've stated your story has an "infinitely advanced civilization," so we're way beyond our mundane physics and into the world of handwaviun, unobtanium, and (new to me, thanks, @fresh_42), duranium. Which means it is counter productive to your narrative to include actual science to answer your question. You'll undermine your story, because if it's within the realms of our possible, then how "infinitely advanced" can this culture really be?

 

[DaveC426913]

... if it's within the realms of our possible, then how "infinitely advanced" can this culture really be?

A good point.

 

[jhami]

only limited by the laws of physics.

 

[DaveC426913]

only limited by the laws of physics.

...the laws of physics... as understood by 21st century Earth, who only invented heavier-than air flight 12 decades ago.

 

[Tom.G]

I'll go along with @DaveC426913.
You seem to be asking :

"What is the most wonderous thing that we don't know about?"

Which is a real contradiction of logic.

 

[Tom.G]

That said, you might look at Graphene.
The drawbacks are that we know about it and the present cost is around 118 000 USD per ton.

 

[member 656954]

only limited by the laws of physics.

I think @DaveC426913 and @Tom.G have appropriately made the point that your scenario seems inconsistent, @jhami, which does make it hard to reasonably respond, but please check out this Forbes article from last year. There may be something you can use in your story.

 

[jhami]

I mean the current laws of physics.

 

[member 656954]

Making the same point again does not change the answer, @jhami. The Forbes article is "current physics", and that's the best we know with our materials science. Other atomic configurations will be developed, but we don't know what they are yet.

If you are writing sci-fi, your options are:

1. Use what's known - the answer of which, on PF at least, does not seem to be acceptable to you.
2. Make stuff up - this is the essence of science fiction and it is a large part of the reason people read it.

An alternative to PF is to reach out directly to materials science experts - you can find them in University staff lists, for example - and ask them, or post on Quora or Reddit.

 

[TeethWhitener]

This thread reminded me of a paper I saw recently that I rather enjoyed:
https://aip.scitation.org/doi/full/10.1063/1.5082739
The main argument is that bulk modulus is dependent on binding energy in the crystal and ultimately valence electron density, which reaches its maximum in diamond (and the closely related cubic boron nitride), such that at ambient pressure, materials with significantly higher bulk modulus (more than about 25% or so) are physically impossible under known laws of materials science.

 

[Stephenk53]

I think he is trying to ask “what is the strongest multi-purpose material possible to ever make?” Which is still unanswerable because we do not know what that limit would be because we have not reached that limit. It is a lot like if a person from the colonial era asked what is the fastest a flying craft could ever be? This is because like that colonist we do not yet know what that limit is because we have not reached the limit (although we still haven’t reached the aircraft limit but it paints a good picture).

 

[FactChecker]

The heaviest material on Earth is osmium, with a density of 22.61 g/cm3. So I assume you are asking for a density under 10, not under 10,000 (using ',' rather than '.'). Is that right?

 

[256bits]

I mean the current laws of physics.

Which would include fabrication, alloys, heat treating, etc.

Even if the physics behind the strongest material says "that's the one", the technological hurdles to make something out of it is a challenge.

Having said that we already know that certain shapes are stronger than others for the amount of material used.
Metal posts are tubes and not solid. Bridges are made with a system of triangular support beams. Cardboard boxes are corrugated,
The weight savings by having empty spaces within a structure means that the structure is "stronger" by not having to support its own dead weight.
That's one way.

Using composite materials is another, such as for skis, and one can get flexibility with strength.

 

[DEvens]

Heh heh.

So the military was flight testing their new design aircraft. And they had a huge failure. The left wing of their prototype broke off the plane. The pilot was exceptionally lucky to be able to eject and parachute to the ground. He was banged up a little, but nothing worse than a few bruises.

So they got another prototype from the manufacturer. And the test pilot took it up to put it through the paces. And again, the left wing broke off. This time the pilot got a broken arm and a concussion.

So they got a third prototype. But this time, they called in the top aircraft engineer from a competing aircraft company to give it a look. And The Great Man (TGM) carefully inspected the aircraft. And TGM made many "hums" and "hems" and "hmmphs" while the team of pilots and generals watched.

Then TGM turned to the assembled group and declared: Bring me a hammer and a chisel!

The pilots looked puzzled. But he was TGM. So they brought him a hammer and chisel. And TGM proceeded to punch a neat row of holes in the wing just where it joined the body of the plane.

When he was done TGM turned to the crowd and declared: It will fly as advertised!

There was a certain amount of excited discussion. But the result was that TGM insisted they test the plane.

So their lead pilot suited up. And cautiously at first, then with more confidence, he took the plane through its designated maneuvers. And it was perfect.

Back on the ground, the excited pilots gathered around TGM. "How did you know? How did you know?"

"Well" said TGM. "It's just like when you want to separate one stamp off a roll. The only place it won't tear is in the row of little holes."

The strongest thing by weight is the material in the holes in a roll of stamps.