B Light (not) escaping from black holes

[Outhouse]

Neutron stars have a very high density, roughly the same density as nuclei but with a larger volume. .

Yet the neutron degeneracy pressure is unknown correct? Said size of neutron is a variable?

What if we view the pressure as a volume knob, why could not a BH be viewed as a NS with the volume turned up from higher pressure?

 

[PeterDonis]

the neutron degeneracy pressure is unknown correct?

I suppose you could say it's "unknown" in the sense that nobody has actually put a pressure gauge inside a neutron star to measure it. But we have detailed theoretical models of neutron stars that include degeneracy pressure and predict the observable parameters of those objects with good accuracy. A good comprehensive (though advanced) reference is Shapiro and Teukolsky, Black Holes, White Dwarts, and Neutron Stars.

why could not a BH be viewed as a NS with the volume turned up from higher pressure?

Because a black hole is not a static object supported against gravity by internal pressure. It is a vacuum; it is "made" entirely of curved spacetime geometry.

 

[Outhouse]

it is "made" entirely of curved spacetime geometry.

Thank you.Cannot we rephrase "curved spacetime geometry" as large amounts of gravity ?

Does the gravity volume level not indicate dense matter is also present?

 

[Outhouse]

[without explaining the relationship of gravity and atomic particle density] If we took gravity and turned the level up to exceed the ability for light to escape from degeneracy pressure of atomic elements, that would not explain what we observe?

 

[PeterDonis]

If we took gravity and turned the level up to exceed the ability for light to escape from degeneracy pressure of atomic elements

I don't know what you mean by this. Pressure is not something that light can "escape" from.

 

[Outhouse]

Pressure is not something that light can "escape" from.

Plenty of light escapes the sun which internally has large amounts of pressure/heat ? Light can also escape a BH at times with luminosities and when quasars are turned on.

I don't know what you mean by this.

For a neutron star, its density raises gravity and degeneracy pressure increased, yet not enough to stop the light from escaping.

Think about adding quasars to the mix here, light is escaping and the guesses I've heard about it being caused by electrical forces seems like a weak hypothesis, I agree its a side effect, but not cause.

Think about why the luminosities are positioned where they are located on the BH. I cannot see them originating from the accretion disk, and see them originating from inside the BH itself.

Sorry nut busting your chops this topic is fun.

 

[PeterDonis]

Plenty of light escapes the sun which internally has large amounts of pressure/heat ?

Sure, but the pressure is not what the light is escaping.

Light can also escape a BH at times

No, it can't. The light you are referring to is not coming from inside the hole; it's coming from hot gas falling into the hole which emits the light while it is still outside the hole's horizon.

Think about why the luminosities are positioned where they are located on the BH. I cannot see them originating from the accretion disk, and see them originating from inside the BH itself.

Nope. See above.

It appears that much of your thinking might be based on the misconception that objects like quasars can emit light from inside a black hole; that is not the case, as I've explained. You need to correct this misconception if you want to understand what's going on.

 

[Outhouse]

it's coming from hot gas falling into the hole which emits the light while it is still outside the hole's horizon.

I have heard some professors describe this as the leading hypothesis, or best guess, and understand your position quite well. I am just investigating the possibilities here.

 

[PeterDonis]

I have heard some professors describe this as the leading hypothesis, or best guess, and understand your position quite well. I am just investigating the possibilities here.

The light being emitted from inside the black hole is not possible. So it's not on the list of things to be investigated.

 

[Outhouse]

The light being emitted from inside the black hole is not possible..

Do we really know that?

I thought another name for a BH is "we don't know"

Maybe I should try asking a different question here. If one could turn the gravity volume knob on a BH down, at some point light would peak through the poles and mirror a quasar 100% as we see them today, luminosities included ?

 

[mfb]

I moved the posts to a new thread as it was off-topic in the old one.

I thought another name for a BH is "we don't know"

No. You underestimate what we know about black holes by a huge margin.

If one could turn the gravity volume knob on a BH down

You cannot. Asking what the laws of physics predict if the laws of physics don't apply is meaningless.

A black hole at the same mass with a lower gravitational constant would be smaller, but still a black hole. Light cannot escape a black hole, that is the definition of a black hole.

Quasars have matter orbiting a black hole outside the event horizon, this matter emits light we see. This is all understood well.

 

[DrGreg]

The light being emitted from inside the black hole is not possible.

Do we really know that?

A black hole is something which by definition light cannot escape from within. So if light is escaping from within some object, that object cannot be a black hole.

 

[Outhouse]

You underestimate what we know about black holes by a huge margin..

Please forgive my ignorance.

My view is that without a working model of gravity, and without a working model of the mechanics of a BH or gravity, I find it hard to see certainties on the mechanics.

I understand there is a great deal that can be observed and measured, but is not much of this still theoretical physics?

laws of physics

I think this all started when I was curious about the neutron degeneracy pressure and its relationship to gravity as seen with neutron stars, and if enough pressure was applied with enough matter, a BH would be formed if the mass was present.

 

[mfb]

My view is that without a working model of gravity, and without a working model of the mechanics of a BH or gravity, I find it hard to see certainties on the mechanics.

We have a working model of gravity and black holes. We have one that withstood thousands of tests. It is called General Relativity.

I understand there is a great deal that can be observed and measured, but is not much of this still theoretical physics?

No, there are countless experimental results testing it.

 

[PeterDonis]

Do we really know that?

Yes.

I thought another name for a BH is "we don't know"

You thought incorrectly, as others have already commented.

I think this all started when I was curious about the neutron degeneracy pressure and its relationship to gravity as seen with neutron stars, and if enough pressure was applied with enough matter, a BH would be formed if the mass was present

There is a maximum mass that a neutron star can have, yes. However, the reason why is not quite what you appear to think. Pressure in an object like a neutron star is not applied inward; it's applied outward. It's what holds the neutron star up against its own gravity. But, as can be shown from the Einstein Field Equation, and as is confirmed by our observational data on neutron stars, pressure itself gravitates; it is part of the source of gravity. So as a neutron star gets more massive, and requires more pressure to hold itself up against its own gravity, its own gravity gets stronger, by more than you would expect just from the increased mass alone.

In addition, as the mass of a neutron star goes up and the pressure required to hold it up against its own gravity rises, the neutrons become relativistic. This reduces the ability of the neutron star matter to hold itself up against gravity with degeneracy pressure, compared to non-relativistic neutrons. (The technical terminology is that the adiabatic index of a Fermi gas--any body of matter made up of degenerate fermions--decreases from 5/3 in the non-relativistic regime to 4/3 in the relativistic regime.) The combination of these two factors--pressure gravitates, and neutrons become relativistic as degeneracy pressure rises--combine to determine a maximum mass for neutron stars, above which no amount of pressure can hold the star up against its own gravity, and it collapses to a black hole.

 

[JulianM]

Yes.
You thought incorrectly, as others have already commented.
There is a maximum mass that a neutron star can have, yes. However, the reason why is not quite what you appear to think. Pressure in an object like a neutron star is not applied inward; it's applied outward. It's what holds the neutron star up against its own gravity. But, as can be shown from the Einstein Field Equation, and as is confirmed by our observational data on neutron stars, pressure itself gravitates; it is part of the source of gravity. So as a neutron star gets more massive, and requires more pressure to hold itself up against its own gravity, its own gravity gets stronger, by more than you would expect just from the increased mass alone.

In addition, as the mass of a neutron star goes up and the pressure required to hold it up against its own gravity rises, the neutrons become relativistic. This reduces the ability of the neutron star matter to hold itself up against gravity with degeneracy pressure, compared to non-relativistic neutrons. (The technical terminology is that the adiabatic index of a Fermi gas--any body of matter made up of degenerate fermions--decreases from 5/3 in the non-relativistic regime to 4/3 in the relativistic regime.) The combination of these two factors--pressure gravitates, and neutrons become relativistic as degeneracy pressure rises--combine to determine a maximum mass for neutron stars, above which no amount of pressure can hold the star up against its own gravity, and it collapses to a black hole.

Could you please clarify what "pressure itself gravitates" means?

 

[Dale]

the gravity volume knob

What is the gravity volume knob? Please provide a reference for what you are referring to here because I have never heard of this.

 

[Dale]

Could you please clarify what "pressure itself gravitates" means?

It means that the source of gravity is the stress energy tensor and pressure is part of the stress energy tensor.

 

[bhobba]

My view is that without a working model of gravity, and without a working model of the mechanics of a BH or gravity, I find it hard to see certainties on the mechanics.

We understand gravity very well, and have a working model as you call it that is very accurate. You may be thinking of a Quantum Theory Of Gravity - we don't have that yet - but our ignorance comes in below about the Plank scale - which is very very small. Then again we aren't sure of any of our theories at that scale since we can't experimentally probe it - yet.

General Relativity isn't that hard either. Particles move according to the Principle Of Maximal Time - which is just Newtons First Law in general coordinates. This leads to something called the metric guv (a 4X4 matrix) determining the motion of particles. This means guv acts like a field and we should be able to use field theory to see what equations it obeys. This is where a not very well known, but a truly amazing theorem, called Lovelocks Theorem comes in:
https://en.wikipedia.org/wiki/Lovelock's_theorem

This gives the Einstein Field Equations that, similar to Maxwell's Equations describing the electromagnetic field, describes the gravitational field guv. It is: Euv = Tuv. (I am ignoring the so called cosmological constant and units so that there is not a constant in front of Tuv). Euv, another 4X4 matrix, is called the Einstein tensor and depends on guv as Maxwell's equations depend on the electric and magnetic field, and Tuv is called the stress energy tensor:
https://en.wikipedia.org/wiki/Stress–energy_tensor.

The Einstein tensor, it turns out, is a measure of space-time curvature so we get that gravity is space-time curvature.

GR itself isn't that hard to get the gist of - it's the math like proving Lovelocks Theorem that is difficult. I have recently gone through the proof again (I did it many years ago but wanted to refresh my knowledge) and it took me a few days - it's very important but trivial to prove it is not.

Thanks
Bill

 

[Outhouse]

There is a maximum mass that a neutron star can have, yes. However, the reason why is not quite what you appear to think. Pressure in an object like a neutron star is not applied inward; it's applied outward. It's what holds the neutron star up against its own gravity. But, as can be shown from the Einstein Field Equation, and as is confirmed by our observational data on neutron stars, pressure itself gravitates; it is part of the source of gravity. So as a neutron star gets more massive, and requires more pressure to hold itself up against its own gravity, its own gravity gets stronger, by more than you would expect just from the increased mass alone.

In addition, as the mass of a neutron star goes up and the pressure required to hold it up against its own gravity rises, the neutrons become relativistic. This reduces the ability of the neutron star matter to hold itself up against gravity with degeneracy pressure, compared to non-relativistic neutrons. (The technical terminology is that the adiabatic index of a Fermi gas--any body of matter made up of degenerate fermions--decreases from 5/3 in the non-relativistic regime to 4/3 in the relativistic regime.) The combination of these two factors--pressure gravitates, and neutrons become relativistic as degeneracy pressure rises--combine to determine a maximum mass for neutron stars, above which no amount of pressure can hold the star up against its own gravity, and it collapses to a black hole.

Thank you very much for spending to the time to show the mechanical explanation, that's what I was after.

 

[Outhouse]

have a working model as you call it that is very accurate

I thought we only measured its effects [Newton/Einstein] and had no idea how GR was actually formed, thank you for the links and reading material.

here was what I meant quoted from wiki [Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward (or gravitate toward) one another,]

Its how they classify it as a Phenomenon, not as a working hypothesis

 

[Outhouse]

What is the gravity volume knob? Please provide a reference for what you are referring to here because I have never heard of this.

Imagining applying more or less mass that increases or decreases degeneracy pressure on atomic elements. neutron, electron, proton

 

[russ_watters]

here was what I meant quoted from wiki [Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward (or gravitate toward) one another,]

Its how they classify it as a Phenomenon, not as a working hypothesis

A phenomenon is just a thing that happens. An hypothesis is a tentative explanation of a phenomenon.

https://www.merriam-webster.com/dictionary/phenomenon

https://en.m.wikipedia.org/wiki/Hypothesis

 

[russ_watters]

Imagining applying more or less mass that increases or decreases degeneracy pressure on atomic elements. neutron, electron, proton

Neutron degeneracy pressure is a threshold - a limit. It is not an operating pressure.

But yes, you can increase the pressure in a neutron star by adding mass.

 

[Dale]

Imagining applying more or less mass that increases or decreases degeneracy pressure on atomic elements. neutron, electron, proton

Then next time say applying more or less mass. “Gravity volume knob” is confusing and highly non standard.

 

[Outhouse]

A phenomenon is just a thing that happens. An hypothesis is a tentative explanation of a phenomenon.

https://www.merriam-webster.com/dictionary/phenomenon

https://en.m.wikipedia.org/wiki/Hypothesis

There is a hypothesis for "this thing" that happens? the actual mechanics behind the weak force?

I apologize for using [ The term is most commonly used to refer to occurrences that at first defy explanation or baffle the observer.] not the scientific philosophy

 

[Outhouse]

Then next time say applying more or less mass. “Gravity volume knob” is confusing and highly non standard.

Will do, fair enough. Thank you.

 

[russ_watters]

There is a hypothesis for "this thing" that happens? the actual mechanics behind the weak force?

Well sure - and not just an hypothesis, but a whole theory(or family of theories)! It's called Quantum Mechanics.

 

[Outhouse]

Neutron degeneracy pressure is a threshold - a limit. It is not an operating pressure.

.

Please forgive my ignorance here, but I understand so far 3 states of a Neutron. #1 natural state, #2 a compressed state where the neutron is compacted with more pressure then its natural state ? #3 understanding it gets unknown to some extent, but its status being in a BH where the Neutron is compressed smaller?

have I misunderstood degeneracy pressure altogether, with its ability to be compressed?

 

[russ_watters]

Please forgive my ignorance here, but I understand so far 3 states of a Neutron. #1 natural state, #2 a compressed state where the neutron is compacted with more pressure then its natural state ? #3 understanding it gets unknown to some extent, but its status being in a BH where the Neutron is compressed smaller?

have I misunderstood degeneracy pressure altogether, with its ability to be compressed?

Yeah, none of that is correct. You might be thinking of "quantum states", but they don't work like that and black holes don't even have identifyable matter.

Where are you getting this stuff from?

 

[Outhouse]

As far as gravity and our lack of knowledge, Neil Degrasse Tyson says it well. "" “we can describe gravity, we can say what it does to other things, we can measure it, we can work with it. But when you start asking what it is, or how it works, I do not know”.""

 

[alantheastronomer]

Neutron degeneracy pressure doesn't refer to a single neutron, it's the pressure between neutrons within a neutron star. As far as neutrons becoming compressed into a singularity as a black hole is formed, we really don't know because our knowledge about what happens inside the event horizon breaks down.

 

[mfb]

As far as gravity and our lack of knowledge, Neil Degrasse Tyson says it well. "" “we can describe gravity, we can say what it does to other things, we can measure it, we can work with it. But when you start asking what it is, or how it works, I do not know”.""

These questions become philosophy. Physics has an accurate description of the phenomenon - that is the best you can hope for. Fundamental "why" questions are philosophy, they are impossible to answer (although some philosophers think otherwise).

 

[Outhouse]

Yeah, none of that is correct.

So just for my

These questions become philosophy. Physics has an accurate description of the phenomenon - that is the best you can hope for. Fundamental "why" questions are philosophy, they are impossible to answer (although some philosophers think otherwise).

This started when I stated we do not really have a working hypothesis as to the mechanics behind it. Its not philosophical IMHO when asking what it is, and how it works. My point, we measure its effects but cannot explain what causes the weak force other than general relativity which is incomplete to the actual nature of gravity.

 

[Outhouse]

Neutron degeneracy pressure doesn't refer to a single neutron, it's the pressure between neutrons within a neutron star. As far as neutrons becoming compressed into a singularity as a black hole is formed, we really don't know because our knowledge about what happens inside the event horizon breaks down.

Thank you very much, that was key for my understanding.

 

[Dale]

There is a hypothesis for "this thing" that happens? the actual mechanics behind the weak force?

Yes, the Standard model explains the mechanics of the strong force, the weak force, and the electromagnetic force. Similarly general relativity explains the mechanics of gravity.

This started when I stated we do not really have a working hypothesis as to the mechanics behind it.

We do: General relativity and the Standard Model

 

[mfb]

The weak force or weak interaction is an independent interaction that has nothing to do with gravity, be careful with that expression unless you actually mean the weak interaction.

This started when I stated we do not really have a working hypothesis as to the mechanics behind it. Its not philosophical IMHO when asking what it is, and how it works.

Physics can give you tools to predict experimental results. That is all physics can do. Everything beyond that is philosophy.

 

[russ_watters]

This started when I stated we do not really have a working hypothesis as to the mechanics behind it. Its not philosophical IMHO when asking what it is, and how it works. My point, we measure its effects but cannot explain what causes the weak force other than general relativity which is incomplete to the actual nature of gravity.

Any question about "how something works" can lead to an endless - and pointless - string of "why" or "how" questions. The reality is that all that really matters is what we can see (observe) - and what is observed is very well described/explained. What we can't observe may not even exist, so it doesn't need an explanation. Talk of "the nature of..." beyond what we observe doesn't lead to any real understanding.

 

[Outhouse]

Talk of "the nature of..." beyond what we observe doesn't lead to any real understanding.

I think it is a lot easier to say we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

We can only measure it we can only partially explain it, in its relationship to bent space/time.

 

[Outhouse]

The combination of these two factors--pressure gravitates, and neutrons become relativistic as degeneracy pressure rises--combine to determine a maximum mass for neutron stars, above which no amount of pressure can hold the star up against its own gravity, and it collapses to a black hole

So it safe to say when the star is over 3 solar masses the gravity overcomes the degeneracy pressure and the neutrons are popped not compressed?

 

[PeterDonis]

I think it is a lot easier to say we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

Only if you know that the concept of "what forms and creates gravity", over and above what we can model using GR, makes sense to begin with. What if it doesn't? That concept comes from the human mind, not nature.

So it safe to say when the star is over 3 solar masses the gravity overcomes the degeneracy pressure

Yes. I believe the current upper limit on the maximum mass for a neutron star is about 2.7 solar masses (we don't know the exact maximum mass, but we know what range it is in), so 3 solar masses is over the limit.

the neutrons are popped not compressed?

I have no idea what you mean by this. If an object made of neutrons collapses to a black hole, the neutrons end up inside the hole.

 

[Outhouse]

If an object made of neutrons collapses to a black hole, the neutrons end up inside the hole.

I see the neutrons being changed/popped, much the same way the hadron collider destroys atomic particles.

Only if you know that the concept of "what forms and creates gravity",

Why can't we use the term a relational theory in regards to general relativity? we observe and report back the mathematical relationship without knowing why the bending of space causes the weak force.

And maybe it was you who mentioned the quantum level here, is what is left to be explained, and I am looking at the exact reasons the two are not cohesive. The actual mechanics causing the force not described by GR

 

[PeterDonis]

I see the neutrons being changed/popped, much the same way the hadron collider destroys atomic particles.

Sorry, I still don't know what this means. The LHC does not "destroy" particles; it just induces high-energy interactions that won't happen under normal conditions here on Earth. Some of those interactions involve particles being converted into other particles.

It's certainly possible that, once a collapsing object like a former neutron star has collapsed to a black hole, and the collapsing matter inside the hole reaches high enough temperature, that interactions similar to what is observed inside the LHC might happen; but that would be well after the collapse has formed an event horizon around itself and is not observable from outside. The LHC interactions have nothing to do with what is inside an ordinary neutron star, or even one that has accreted some matter and is now over the maximum mass limit and is collapsing to a black hole, but has not yet formed a horizon.

Why can't we use the term a relational theory in regards to general relativity? we observe and report back the mathematical relationship without knowing why the bending of space causes the weak force.

The bending of spacetime does not "cause" gravity (and gravity is not the same as the weak interaction; that's a separate interaction, which is involved in processes like nuclear beta decay). The bending of spacetime is gravity. They're just different names for the same thing.

Asking why spacetime bends in the presence of matter and energy is like asking why the laws of physics are what they are. There's no way to resolve such a question experimentally, so it's off topic here.

im looking at the exact reasons the two are not cohesive

Meaning quantum mechanics and GR? It's because nobody knows how a quantum theory can coexist with a non-quantum theory. The only thing we understand is how to figure out the classical limit of a quantum theory; but we don't know any quantum theory of which GR is the classical limit. (The search for a theory of quantum gravity is the search for such a quantum theory, but so far it has not come up with one that has been confirmed to work.)

The actual mechanics causing the force not described by GR

In GR gravity is not a force at all; it's spacetime curvature.

 

[russ_watters]

I think it is a lot easier to say we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

We can only measure it we can only partially explain it, in its relationship to bent space/time.

Again, "partially explain" means there are observations it doesn't explain. What are those observations? If you can't think of any specifics, then you can't say, scientifically, that it is incomplete.

If the claim is based on vague how/why questions, then they are outside the scope of science.

 

[Outhouse]

The LHC interactions have nothing to do with what is inside an ordinary neutron star

Yes agreed.

The LHC does not "destroy" particles

Not a scientific word true, but protons are brought to a state of byproducts by collision and then studied as they decay.

There's no way to resolve such a question experimentally

We cannot test infinite experiments, but cannot we use Perturbation methods to help us form plausibility of a workable reconciliatory hypothesis?

 

[Outhouse]

If the claim is based on vague how/why questions, then they are outside the scope of science.

We don't have meaningful physical predictions of quantum field theory and gravity bosons, correct?

[WIKI] A bigger challenge is to find a way to quantize the gravitational field, resulting in a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces.

 

[russ_watters]

We don't have meaningful physical predictions of quantum field theory and gravity bosons, correct?

[WIKI] A bigger challenge is to find a way to quantize the gravitational field, resulting in a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces.

Parts of that are still a work in progress, but there are lots of "meaningful predictions" that work. And here's what you said before:

...we don't know the first thing about what forms and creates gravity beyond general relativity and the Standard Model, which are incomplete.

The statement has more twists than a pretzel. "Don't know the first thing" except what we know (GR and the standard model), which is a lot. The way you write it implies we know 1% when in reality we know 99%.

 

[PeterDonis]

cannot we use Perturbation methods to help us form plausibility of a workable reconciliatory hypothesis?

No. This has been tried; in the 1960s a number of physicists, including Feynman, worked on constructing a quantum field theory of a massless spin-2 field, which theoretical considerations said should be the graviton, the quantum of gravity. They found out that, when a perturbative theory of such a field was constructed, correct to all orders, its field equation was simply the Einstein Field Equation of GR. The problem was, this theory was not renormalizable, so all the field equation really tells you is the low energy limit; it doesn't tell you anything about quantum gravity at higher energies, which is what we need to know.

We don't have meaningful physical predictions of quantum field theory and gravity bosons, correct?

If by "gravity bosons" you mean the massless, spin-2 graviton, GR is the "meaningful physical prediction" of such a QFT at low energies (see above). The problem is that "low energies" here means "energies small compared to the Planck energy", and the Planck energy is about 20 orders of magnitude larger than the largest energy we can probe with our experiments (the LHC energy). So basically what our current knowledge of quantum gravity tells us is that whatever the quantum nature of gravity is, it's completely negligible as far as experimental predictions at any energy less than about 20 orders of magnitude larger than the largest energy we can currently probe experimentally. Which isn't very useful, but there it is.

 

[PeterDonis]

a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces.

While this is what most physicists probably expect, it's worth keeping in mind that we don't know that this is how things will come out. Some physicists (Freeman Dyson is one notable one among them) have expressed the opinion that we might end up finding out that gravity is not like the other interactions and can't be unified with them. Not as a theory to be tested, but as a possibility not to be ruled out at this very rudimentary stage of our knowledge.

 

[bhobba]

Asking why spacetime bends in the presence of matter and energy is like asking why the laws of physics are what they are. There's no way to resolve such a question experimentally, so it's off topic here.

That's exactly it.

There are certain laws we are pretty sure of such as the formalism of Lagrangian Field Theory. You combine that with considering space-time in generalized coordinates and mathematically describing it by what's called a pseudo-Riemannian geometry (fancy name for curved space time) pretty much leads to GR. Why are all those things true? Well I can explain them, and even derive some of them from more fundamental laws such as the symmetry of an inertial frame, and even make it sound very reasonable to the point you say - yes I see why nature is like that - but really at a fundamental level what have you done.

For example the following makes SR (flat space-time) seem almost inevitable:
http://www2.physics.umd.edu/~yakovenk/teaching/Lorentz.pdf

After reading that you may say - I know why SR is true - and in a certain sense you do - but in another sense you do not - you are faced with the question - why do inertial frames exist with those symetry properties?

You merely replace some assumptions with others. Natures laws are as natures laws are - we just describe them - although they can be described in a clear and illuminating way (like the above paper), which is something I love to do, it must always be borne in mind that's all we are doing is describing natures laws. Nature determines them - not us.

Thanks
Bill