*CRICKETS*

The perturbations, resulting in vibration, that would be caused by any amount of imbalance would tear that thing apart in any reality outside of an ill conceived mathematical concept.

solrey, which reality are you talking about?

But I have another story for you: Have you ever heard of the supernova SN 1987A?
The same time the light of the explosion reached us we also detected a hugh wave of neutrinos. These were the only non-solar neutrinos ever detected coming from outer space. Where did they come from? I think it's reasonable to link them to the SN. But how did it creat such high numbers of neutrinos?
Probably (and most likely) via "inverse beta-decay". An electron and a proton combine to form a neutron. In order to conserve the lepton number, an electron-neutrino must be sent out.
Hmmm….. So, if hugh numbers of neutrons were created during the SN, we should've detect high numbers of neutrinos. But it's not that easy to force electrons into a proton – in order to achieve such high numbers you need a very strong force. A gravitational collapse can provide exactly that.

So to sum up: We have a SN and we detect a hugh flow of neutrinos. The only way to creat that flow is with the inverse beta-decay: Electrons and protons creat neutrons during a gravitational collapse. Since neutrons are fermions the matter will degenerate and become stable (if the core is not too massive) – a neutron star is born.

Do you have a better explanation?

Neutron stars with significant instabilities, in particular magnetic instabilities, can force an Earth equivalent amount of crust hurling out at 1/2 the speed of light by magneitc force. This is then quickly forced back by gravity to the neutron star. Extreme stuff.

Lawrence B. Crowell

I recall reading somewhere that if you stood on the surface of a neutron star, "you would cover the entire surface, several molecules thick."

The 10^{-15}m for gravity waves refers to the amplitude of the gravity wave, not the size of the asymmetry (mountain) on the neutron star which would generate them.

Neutronium is just a term for the matter state of neutrons in a neutron star. It is not often used in astrophysics literature. I suppose there is too much reference in science fiction and StarTrek which prevents its use.

I am not sure of the exact state of this "neutronium." I would imagine after implosion it is a gas. Just as density and pressures are enormous so are temperatures. If it gets cold enough, say within 10^{100} years as the neutron star comes to thermal equilibrium with a near zero temperature universe, that it might exhibit a phase transition to a solid. I am unaware of research into the phase structure of neutron matter — neutronium.

Lawrence B. Crowell

Would not the gravity of the star actually decreased due to mass loss during the nova event?

You are right. The star loses most of its mass in the nova event. A neutron star has masses of about 1.4 to about 3.8 solar masses (if I remember correctly). It cannot have more mass, otherwise it would become a black hole.
But we are talking about an object of the size of a city and, as I said, with a mass of probably 2 solar masses. That's f***ing dense! So the gravity close to the surface of the neuron star is incredibly strong. On the other hand, a planet farther out (that somehow managed to survive the explosion) will increase its distance due to the lower gravity (due to the lower mass) of the central object.

that's correct, I reckon – if the mass of both, Earth and Sun (now a black hole), remains the same.
You can look up Schwarzschild Radius – all massive objects have one, and it's a function of the mass. In a star, like the Sun, it lies well within the volume of the star, deep underneath the surface. For a Black Hole, it marks the event horizon.
The escape velocity from a massive object from within the Schwarzschild radius would have to be greater than the speed of light (that's roughly how the SR is defined), hence nothing can escape, even under acceleration.
Anyhow – the net result is: The orbit of the Earth wouldn't change – it lies well outside the SR.

The way I understood things is that if our sun today somehow turned into a black hole (without obliterating our solar system in the nova event), the earth would continue to happily orbit.

In the article.

" The crust could be so strong as to be able to elicit gravitational waves that could not only limit the spin periods of some stars… "

Would not the gravity of the star actually decreased due to mass loss during the nova event?

Which just like Allotropic Iron is essentially a energy fluid state if I understand correctly.

I guess us earthlings like to think of things as solids we can use, but Its always fun to remember that all matter is energy anyway.

Must read the Lensman series one day.

The core of a star solidified.

Would make a good plot for a Sci-Fi. But is it even halfway plausible?

Damian

As for gravity waves, for the metric h_{ab} correction the linearized wave equation is

&^2h_{ab} = (16 pi G/c^4)T_{ab}.

for & = partial. So the laplacian on the left brings down a frequence ~ k^2 or omega^2. We consider the stress-energy as density = 10^{13}g/cm^3. Then ball parking the numbers this would lead to an amplitude of about

h_{ab} ~ 10^{-28}x10^{13}x10^{2}eta_{ab},

or about 10^{-13}cm or a femtometer.

Lawrence B. Crowell