Questions about a neutron star

I understand a lot about how they are supposed to work but, if Gravity is supposed to stabilize the neutron decay rate by converting protons and electrons to neutrons and whatever mechanism Gravity has on neutrons to not decay back then my question is why in the center of the star where gravity is zero or low does the neutron not still decay? Gravity stops and stabilizes the outer region but as you get deeper it has less effect. Just curious if anyone can correct me or explain what I'm missing. Is it purely from kinetic pressure?

originally posted by: NiZZiM
I understand a lot about how they are supposed to work but, if Gravity is supposed to stabilize the neutron decay rate by converting protons and electrons to neutrons and whatever mechanism Gravity has on neutrons to not decay back then my question is why in the center of the star where gravity is zero or low does the neutron not still decay? Gravity stops and stabilizes the outer region but as you get deeper it has less effect. Just curious if anyone can correct me or explain what I'm missing. Is it purely from kinetic pressure?

I think as gravity drops pressure increases to "make up " for it. From the wight of all the "gravity" above the centerpoint. That and the true center where gravity is zero could be microscopic.


Just a guess from watching way too much Morgan freeman! Lol :p

originally posted by: NiZZiM
I understand a lot about how they are supposed to work but, if Gravity is supposed to stabilize the neutron decay rate by converting protons and electrons to neutrons and whatever mechanism Gravity has on neutrons to not decay back then my question is why in the center of the star where gravity is zero or low does the neutron not still decay?

Here is the answer to that question about the center of the Earth but it would be similar for a neutron star in that while gravity may be zero, pressure wouldn't be zero:

Effect of pressure and gravity at the center of astronomical bodies

Maximum pressure is in Earth's mass center. As, you say, all gravity forces cancel each other out at the center since the mass of Earth is symmetrically distributed around you. But the pressure in one point does not just depend on gravity in that point. Pressure is due to the weight of everything above you, and in those points, gravity is definitely not zero. Pressure is the integral of gravity (multiplied by mass density) from where you are all the way up into space. Hence, the pressure gradient is proportional to gravity and the fact that gravity is zero in the center of Earth is consistent with it being the pressure maximum

I wouldn't be surprised at all if neutrons near the surface do decay where pressure is the lowest. A neutron star may not be neutrons all the way to the surface, but when the pressure increases at some depth it probably is neutrons from that depth and lower.

a reply to: NiZZiM

Because we still have a LOT to learn about what is really inside our various stars...

a reply to: Arbitrageur

Here is the answer to that question about the center of the Earth but it would be similar for a neutron star in that while gravity may be zero, pressure wouldn't be zero:

pressure ? what is this pressure exactly ?
Pressure means a lot of movement as it increases with temperature.
Are you saying neutrons are oscillating over bigger and bigger distance if you go closer to the center ?

What repels them if they don't interact with each other at distance like charged particles do ?

There's a fellow here who has a different model of the subatomic world. Its worth watching his lectures - he admits his model must explain all observed phenomena and he does so, without the need for dark matter and other 'voodoo' as he calls it. The lectures are interesting, and he has some on the big bang, the sun, black holes etc - there might be some answers to this question buried in there:

Youtube page
Check out the playlists.

Cheers

ps I have watched the set now, many twice, and can not break his model - would love to have someone else do it (but scientifically - not emotionally - he does put a lot of #e on some famous people)

originally posted by: KrzYma
pressure ? what is this pressure exactly ?
Pressure means a lot of movement as it increases with temperature.

Pressure is force per area. Put a 100 pound weight on a one square inch area and that creates a pressure of 100 pounds per square inch.

You might be thinking of the ideal gas law which describes a relationship between temperature and pressure, but in neutron star discussions, we aren't talking about gases.

I scuba dive and when I go in the water, the temperature usually decreases as pressure increases with increasing depth, so in that case if there's any relationship at all between temperature and pressure, it's inversely correlated but as you've probably heard before, "correlation does not equal causation". If you go to the bottom of the ocean the pressure gets very high and the temperature gets low. In other cases they may be correlated, but temperature and pressure are two different things. Temperature in interstellar space can be a million degrees, but the pressure is so low the vacuum where the temperature is a million degrees is better than the best vacuum pump on Earth can make.

Here's a graph of ocean temperature showing the temperature typically goes down as you get deeper, though of course you could have exceptions like at undersea volcanoes:

www.bigelow.org...

Pressure increases approximately one atmosphere for every 10 meters of depth, so in this case, temperature is decreasing as pressure is increasing.

What repels them if they don't interact with each other at distance like charged particles do ?
And what stabilize the neutrons from decay if there is no charge and no E field,
you told me +1 + -1 = 0

originally posted by: KrzYma
What repels them if they don't interact with each other at distance like charged particles do ?

Who said they were repelled?

And what stabilize the neutrons from decay if there is no charge and no E field,
you told me +1 + -1 = 0

See my first post in this thread.

those kind of topics are so difficult to develop a framework where a solution can be found...can you provide a real life example so the concept can be applied?

a reply to: michaelbrux
Indeed we haven't performed any direct experiments on neutron stars as we've never been to one and any attempt to land on one would crush the probe, so we have to make extrapolations from what we do know in real experiments.

You could start with scattering experiments such as the Rutherford experiment which told us that atoms have very small nucleii. On the scale of a stadium an electron cloud might be in the bleachers and the nucleus would be like a marble on the middle of the field, so we know that atoms are mostly space with that kind of structure, from observation.

We also know that high pressures tend to squeeze things together...think the car compactors at junk yards.

So if you combine those two concepts in an oversimplified fashion, you end up with the idea that something very "fluffy", an atom, can get compressed to something many times smaller under extreme pressure, which in the case of a neutron star is provided by gravity.

Here's a video you can watch on a real world experiment where air pressure crushes a 55 gallon steel drum, so just imagine this but with gravitationally-induced pressure crushing atoms into neutronium (a very crude analogy):



Just as air pressure made that drum less "fluffy", pressure in a neutron star makes what we normally think of as matter less fluffy, to the extent a teaspoon of it has more mass than 900 great pyramids of Giza.

Neutron stars are a french fry shy of having become a black hole. As such, the absolute centers of these neutron stars, which are only 10km in radius, is as understandable as black holes themselves, in which we still do not understand the true concept of the singularity. The discovery of the central entity of either one, will have to account for the existence of the other one.

i notice alot of science fiction stories feature neutronium a substance mined from te the neutron shell of a neutron star but the minute you removed said material from stars tremendous gravity wouldn't it explosively decompress?

originally posted by: proteus33
i notice alot of science fiction stories feature neutronium a substance mined from te the neutron shell of a neutron star but the minute you removed said material from stars tremendous gravity wouldn't it explosively decompress?

I don't see how it could be mined in the first place since any mining equipment would probably get sucked in by gravity and crushed.

Secondly, even if you could get mining equipment to scrape some off the surface, it's probably not neutronium since the pressure is at a minimum on the surface and neutrons would have likely already decayed there.

The neutronium is below the surface, so you'd have to dig for it (probably impossible or close enough). When you brought it to the surface, like the surface material it wouldn't stay neutrons for long since they have a mean lifetime of about 15 minutes, but the neutron decay has a random variability to it so it probably wouldn't all decay at once, meaning I'm not so sure it would explode. It wouldn't' stay neutronium very long though.

a reply to: Arbitrageur

Who said they were repelled?

you said there is a pressure, I started with gases, you talked about liquids.
All those molecules repel and pressure is not just some result of multiplication like your first post is saying.

Are you saying that all the neutrons are like spheres tightly together with no space in between?

What makes a neutron stable in a nucleus, the other neutron, the other protons or electrons ?
Or is it because neutrons somehow know they shouldn't decay ?
I'm asking because neutron stars don't have protons or electrons and lithium has a single one,

Can't be pressure if I look at atoms...

so what is it ??

originally posted by: KrzYma
Can't be pressure if I look at atoms...

Why not? Atoms have electrons "orbiting" them. Material in the core of a neutron star is not believed to have "orbiting" electrons. The pressure is too great.

originally posted by: Arbitrageur
Why not? Atoms have electrons "orbiting" them. Material in the core of a neutron star is not believed to have "orbiting" electrons. The pressure is too great.

why not?, your formula, gravity times mass density won't work or can it ?

originally posted by: KrzYma

originally posted by: Arbitrageur
Why not? Atoms have electrons "orbiting" them. Material in the core of a neutron star is not believed to have "orbiting" electrons. The pressure is too great.

why not?, your formula, gravity times mass density won't work or can it ?

Yes my first post explained it. Gravity is zero where pressure is the highest, so obviously the formula for pressure is NOT gravity times mass density, because if that was the formula, pressure would be zero at the center where gravity is zero. Gravity is zero at the center but pressure is not, it's at the highest value.

Read more carefully.

originally posted by: Arbitrageur

originally posted by: KrzYma

originally posted by: Arbitrageur
Why not? Atoms have electrons "orbiting" them. Material in the core of a neutron star is not believed to have "orbiting" electrons. The pressure is too great.

why not?, your formula, gravity times mass density won't work or can it ?

Yes my first post explained it. Gravity is zero where pressure is the highest, so obviously the formula for pressure is NOT gravity times mass density, because if that was the formula, pressure would be zero at the center where gravity is zero. Gravity is zero at the center but pressure is not, it's at the highest value.

Read more carefully.

I was talking about atom and your formula and not neutron star and the center of it

a reply to: KrzYma
Neutrons aren't always stable in atoms. Sometimes they do decay.

But the reason they usually don't decay in stable atoms is because if the decay were to occur, the resulting proton would be trying to assume the lowest energy state possible, but the Pauli exclusion principle puts limits on what energy states are available to it, because there are already other protons in the nucleus occupying those lowest energy states. So, if a decay results in the proton being forced into a higher energy than the neutron was at, then the decay will be unlikely to proceed spontaneously because such decays occur from higher energy state to lower energy state, not the other way around.