Gravity collapse SJC.

[petemcewan 27]

Woolyhead, Angelfire1 and Hairyloon.

 

As I understand :

 

The implosion of a star resulting from its own gravity; the result is a smaller and denser celestial object.

 

Just to be clear. I'm not passing myself off as an expert astrophysicist. I can follow some of the associated maths-but not all of it.

 

I find the subject fascinating and I'm interested in what others on the Forum think.

 

There are aspects of the maths and theory of gravutation collapse and black holes that puzzle me.

 

I think of gravity as "gravitational force" . Force is a vector not a scaler. So it puzzles me when I see an equation -associated with gravitational collapse- expressing terms such as , " investigated the gravitational collapse of a massless scalar field".

Edited August 27, 2017 by petemcewan

[Jeffrey Shaw 90]

what if Uranus is so big it generates its own gravity ?

Uranus would presumably be a black hole disappearing up its ring.

[petemcewan 27]

Jeffrey Shaw,

 

You'll like this. Taking the weight out of gravity.

 

 

 

Or maybe this is a little more creative.

 

 

 

7 X 13 = 28.

Edited August 28, 2017 by petemcewan

[woolyhead 15]

I see. And neither am I an expert on this but when I look at Einstein's derivation of his field equations I see that he just wrote G as the gravitational constant following Newton, not the result of being close to massive objects but a universal constant which applies everywhere in spacetime. Where if anywhere is gravity supposed to originate then? Does it come from all the mass in the universe? By the same token where does inertia originate - the stars?

Edited August 30, 2017 by woolyhead

[medusa 16]

If you're answering SJCrothers you need to know that he hasn't logged in to the forum since 5 August.

[monkey104 10]

It would only end in verbal fisticuffs anyway.

[Hairyloon 10]

If you're answering SJCrothers you need to know that he hasn't logged in to the forum since 5 August.

 

As far as I can tell, we are just discussing physics. If OP participates or not, it doesn't really matter.

 

I won't ask if he's been suspended...

 

---------- Post added 30-08-2017 at 20:32 ----------

 

Where if anywhere is gravity supposed to originate then?

 

Physics predicts that it is something to do with the Higgs Boson.

[woolyhead 15]

I think the Higgs boson is the particle version of the Higgs field which confers mass on particles. Mass isn't gravity.

[petemcewan 27]

Wooleyhead,

 

The existence of the Higgs field implied an associated FORCE-carrying particle - the Higgs boson.

The standard model says, the greater the mass ( a scalar quantity) the greater the gravity. As the Boson is a FORCE (vector quantity) carrying particle and gravity is a FORCE. Is it stretching it, that the boson is responsible for gravity?

 

 

 

Note:

 

Subatomic particles are either MATTER carriers called fermions-such as electrons and protons, or FORCE-carrying particles called bosons, such as photons and gluons.

The existence of the Higgs field implied an associated FORCE carrying particle, called the Higgs Boson, which is like a ripple in that field- so they say.

Edited September 1, 2017 by petemcewan

[achorste 10]

SJCrothers,

 

Just an inquiry.

 

 

 

 

Why is the field expressed as a Scaler quantity and not a Vector quantity (having magnitude and direction ) ?

 

It is scalar as it is the potential force at a point (for whichever force the field is related to), once there is interaction with that field, the effect is a vector force (which has direction).

[esme 10]

...Why is the field expressed as a Scaler quantity and not a Vector quantity (having magnitude and direction ) ?

 

From a quick look at wikipedia I'd say it's because a scalar field is not the same as a scalar quantity

 

A scalar field associates a scalar value to every point in a space.

 

This space may be mathematical or physical, the scalar value can represent, mass, charge, number of angels dancing, pretty much anything.

 

As this is referring to the gravitational collapse of a scalar field, I would say we are starting with a volume of spacetime, looking at the mass at every point in it and determining how the gravitational attraction of each point to every other point governs the way the mass distribution changes over time.

 

As gravity is an attractive force this change of mass distribution over time would tend to pull the mass together or collapse it towards a single point.

 

Because the mass at every point in the scalar field is attracted to every other point in the scalar field, a vector quantity would have to represent the force at that point which could only be determined by summing the force between each point and each other point to determine a resultant force.

 

I would say working out these vectors would be the first step in determining how the field evolves over time, then you apply a small step of time to see how the mass changes & recalculate all these vectors again a bit like finite element analysis, there may be a simpler technique though.

 

So a scalar field tells you everything you need to know, you can work out the force vectors which means they aren't needed to describe the field.

 

But that's just a guess.

Edited September 1, 2017 by esme

[petemcewan 27]

Achorste, Esme,

 

That's a pretty could "guess ".

 

It is a scalar as it is the potential force at a point (for whichever force the field is related to), once there is interaction with that field, the effect is a vector force (which has direction).

 

Thank you for having the patience to explain.

 

Taking literally: "potential force at a point ".

 

So it's like taking an "instantaneous " value of the gravitational field -similar to the way one takes an "instantaneous " value of an alternating magnetic field? Many "instantaneous " values- over time -can give one a view of the activity of the field.

 

 

I think I'm getting close and baba boom baba bing! It all collapses again.

 

https://profmattstrassler.com/2012/10/15/why-the-higgs-and-gravity-are-unrelated/

 

I'm going down the pub-things are much more simple on the outside of a

 

Farmer's stout. Me head is swimming with Tensors and Metrics.

 

An interesting video presented by a great mind.

 

 

---------- Post added 11-09-2017 at 10:23 ----------

 

Gravity phenomena,

Newton:

Issac Newton postulated that gravity existed throughout the universe and that all

matter attracted each other.Newton theorized that the Sun, Earth and the Earth’s moon were attracting each other and that it was only their relative orbital speeds that prevented them all from smashing into each other. Newton also theorized gravity as being instantaneous. Newton gives us his laws of gravity which describe its effects but doesn’t explain it.

A particular problem with Newton’s orbital attracting theory is how can nature govern the speed of the celestial bodies in space in relation to their distances so accurately, and without spinning away or decaying inwards?

 

Einstein :

He reviewed Newton’s universal gravity by postulating that gravity as such doesn’t exist.

For Einstein acceleration is indistinguishable from gravity, and that any gravitational field of force -at any point- in space is in every way equivalent to an artificial field of force resulting from acceleration.

To account for acceleration to explain gravity in the universe- and on earth- Einstein came up with the idea that space is curved-space tells matter how to move and matter tells space how to curve.In addition|Einstein’s warped space is considered to produce gravity waves in the universe.

 

Everything is falling -stars and planets must follow the path of curved spacetime,

S, stars moving at incredible velocities in their journey around a black hole.

However, Einstein’s explanation of gravity is incomplete. There’s still more to learn. However gravity is a universal and instantaneous force (here the term is not referring to the universe but to the notion of universality — of complete generality.

 

(Note, Predicting the orbit of Mercury around the Sun contributed to the rethinking of Newton’s theories and the development of the theory of curved spacetime).

 

KInetic Energy Theory: Le’ Sage.

 

A mechanical explanation of gravity. Le’Sage was a close mate of Newton. Newton considered L’e’Sage’s theory to be the best mechanical theory of gravity.

Gravity can be considered as the behavior of the kinetic energy contained in all matter.

 

Electric Gravity:

 

" Every particle within each atom is made of zero mass charges.Every subatomic particle is distorted by the presence of others to form a tiny electric dipole. Like magnets that are free to rotate, all the electric dipoles in protons, neutrons, and electrons line up to produce gravity.Neutral atoms that are distorted gravity, induce an electric field inside a body " .

 

Higgs Gravity:

 

 

“Higgs field is not the universal giver of mass to things in the universe: not to ordinary atomic matter, not to dark matter, not to black holes. To most known fundamental particles, yes — and it is crucial in ensuring that atoms exist at all. But there would be just as much interesting gravitational physics going on in the universe if there were no Higgs field. There just wouldn’t be any atoms or any people to study them.”

 

 

Read the link if you please.I definitely thought they had it. However, energy and momentum seem to be the superior to mass.

 

https://profmattstrassler.com/2012/10/15/why-the-higgs-and-gravity-are-unrelated/

Edited September 11, 2017 by petemcewan