<p>The paper is discussing &quot;strength&quot; in terms of the <a href="https://en.m.wikipedia.org/wiki/Shear_modulus" rel="noreferrer">shear modulus</a>, which is the resistance of a material to shearing forces, not its resistance to compression. A shear modulus of <span class="math-container">$10^{30}$</span> erg/cm<span class="math-container">$^2$</span> is about 25 orders of magnitude larger than that of steel.</p>
<p>The deep interior of a neutron star, interior to any nuclear pasta phase,  is a fluid. A fluid does not have a shear modulus. Instead it has a <a href="https://en.m.wikipedia.org/wiki/Bulk_modulus" rel="noreferrer">bulk modulus</a>, which is a small multiple of the gas pressure, and measures the resistance of the material to compression.</p>
<p>The gas pressure does indeed increase towards the centre of the neutron star. In conclusion, the fluid at the centre is less compressible than nuclear pasta, but nuclear pasta is &quot;stronger&quot; in terms of resistance to shearing forces.</p>

CC BY-SA 4.0
2023-09-21T22:29:17.577Z
2023-09-21T22:29:17.577Z
ProfRob
<p>From my very rudimentary understanding of neutron stars taken from the abstract to &quot;<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.132701" rel="noreferrer">Elasticity of Nuclear Pasta</a>&quot;, nuclear pasta is the strongest substance, hence the strongest part of a neutron star.</p>
<blockquote>
<p>Our results show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of <span class="math-container">$10^{30}$</span> ergs/cm³ and a breaking strain greater than 0.1.</p>
</blockquote>
<p>It seems like unbelievable pressure can only increase the closer to the core of the star. With all of the particles condensed, wouldn't <em>that</em>– the core– be the strongest part? Not the pasta?</p>

CC BY-SA 4.0
2023-09-21T19:40:47.343Z
I suspect something like https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.132701  "Our results show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of 10^30 ergs/cm³  and a breaking strain greater than 0.1."
James K
CC BY-SA 4.0
2023-09-21T19:44:52.480Z
@JamesK Yeah, I got it from the abstract.
Ben A.
CC BY-SA 4.0
2023-09-21T19:53:22.800Z
Okay I've edited based on hyour comment.
James K
<astrophysics><neutron-star>
Why is nuclear pasta the strongest part of a neutron star?
Ben A.
# Why is nuclear pasta the strongest part of a neutron star?

(Asked by: username_0 on 2023-09-21)

From my very rudimentary understanding of neutron stars taken from the abstract to "[Elasticity of Nuclear Pasta](https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.132701)", nuclear pasta is the strongest substance, hence the strongest part of a neutron star.

> Our results show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of $10^{30}$ ergs/cm³ and a breaking strain greater than 0.1.

It seems like unbelievable pressure can only increase the closer to the core of the star. With all of the particles condensed, wouldn't *that*– the core– be the strongest part? Not the pasta?

**Tags:** astrophysics, neutron-star

> **Comments:**
> **username_1**: I suspect something like https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.132701  "Our results show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of 10^30 ergs/cm³  and a breaking strain greater than 0.1."  
> **username_0**: @JamesK Yeah, I got it from the abstract.  
> **username_1**: Okay I've edited based on hyour comment.  

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## 1 answers

### Answer by username_2 on 2023-09-21. Score: 5 | Accepted answer

The paper is discussing "strength" in terms of the [shear modulus](https://en.m.wikipedia.org/wiki/Shear_modulus), which is the resistance of a material to shearing forces, not its resistance to compression. A shear modulus of $10^{30}$ erg/cm$^2$ is about 25 orders of magnitude larger than that of steel.

The deep interior of a neutron star, interior to any nuclear pasta phase, is a fluid. A fluid does not have a shear modulus. Instead it has a [bulk modulus](https://en.m.wikipedia.org/wiki/Bulk_modulus), which is a small multiple of the gas pressure, and measures the resistance of the material to compression.

The gas pressure does indeed increase towards the centre of the neutron star. In conclusion, the fluid at the centre is less compressible than nuclear pasta, but nuclear pasta is "stronger" in terms of resistance to shearing forces.


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