Maximum Gravitational Force

[TheBigDog]

Is there a maximum gravitational force that an object can exert, similar to how the speed of light is the maximum velocity?

 

I have been thinking about this in regard to black holes. If a black hole exists in the center of a galaxy, it would be slowly but surely absorbing all of the matter of that galaxy. As it absorbs more matter it would gain mass and increase its gravitational force. This would keep increasing constantly as more matter was absorbed by the hole. The event horizon would grow outward until it had absorbed the entire galaxy. And then it would be a massive void in space absorbing additional galaxies that strayed into its area of influence. If that were the case it would be rare to see any old galaxies. Or their would be evidence of them shrinking.

 

Instead I think we are seeing a steady state, if you will, where the mass orbiting the black hole is in actually at an equilibrium. This would not happen if the black holes were constantly packing in more and more gravitational force. Everything in the galaxy would be in a decaying orbit as the gravity of the whole was constantly increasing.

 

This could could also play into the notion of "Hawking Radiation". If such radiation does exist, it would indicate not only the particle halves escaping the close proximity of the event horizon, but the particle halves trapped by it. That alone would mean that a black hole was a constantly growing entity.

 

Because I don't think we are witnessing such behaviors, I am left to conclude that there is a maximum gravity for a body. If this is so, what would it mean to the mathematics of General Relativity?

 

Bill

[InfiniteNow]

You might start here, but your question about a limit to the force of gravity is interesting all the same.

 

Cheers!

 

http://chandra.harvard.edu/press/05_releases/press_021505.html

http://www.sciencedaily.com/releases/2005/02/050222195058.htm

[TheBigDog]

You might start here, but your question about a limit to the force of gravity is interesting all the same.

 

Cheers!

 

http://chandra.harvard.edu/press/05_releases/press_021505.html

http://www.sciencedaily.com/releases/2005/02/050222195058.htm

Thanks Infinite! Interesting reading. I will chew on that for awhile.

 

Bill

[CraigD]

Is there a maximum gravitational force that an object can exert, similar to how the speed of light is the maximum velocity?

Depends on the model used to describe gravity.

 

If you model it with General Relativity, which is essentially an extension of classical mechanics, gravitational force is replaced by space-time curvature as an explanation for gravitational acceleration, and a maximum space-time distortion exists. I’m not sure how to calculate it, but think it would be the gravitational field at the precise event horizon of a black hole.

 

If you model it with the extension of the Standard Model of Particle Physics that contains a “graviton” boson, it’s possible there is no maximum. Bosons aren’t restricted by the Exclusion Principle, so, like photons, an arbitrary number of them should in principle be able to interact with a single particles in an atom to producing an arbitrarily large force. How one would do this (create a gravitational acceleration in excess of that predicted by GR) is mysterious to me.

 

GR is only an approximate description of mechanics. Gravitons are not yet adequately modeled, so aren’t an accepted part of the Standard Model. So I think the best answer to TheBigDog’s question is at best hypothetical speculation. Some exotic Unified Theory/Theory of Everything (Strings, Branes, Holographic, Graphs, etc.) may turn out to be correct, and disagree with any extension of the Standard Model’s answer to this question.

[Harry Costas]

Gravitational force is a constant.

 

As for the size it depends on the mass.

 

As for Black Holes ,they are not void.

[TheBigDog]

Gravitational force is a constant.

 

As for the size it depends on the mass.

 

As for Black Holes ,they are not void.

Would you care to elaborate on any of that?

 

Bill

[EWright]

Gravitational force is a constant.

 

As for the size it depends on the mass.

 

As for Black Holes ,they are not void.

 

The speed of gravity is thought to be equal to the speed of light... however, objects with more mass do exert more gravitational influence, so it is not constant or rather 'equal' in that sense.

[Harry Costas]

The speed of Gravity does not equal the speed of light.

see links

 

http://metaresearch.org/cosmology/gravity/possiblenewpropertiesofgravity.asp

 

http://hyperphysics.phy-astr.gsu.edu/hbase/grav.html#grav

 

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c2

 

http://mywebpages.comcast.net/adring/Persson_invisible.pdf

 

http://www.newscientist.com/article.ns?id=dn2796

 

http://metaresearch.org/cosmology/speed_of_gravity.asp

 

 

Just a few links

But! there is more

[arkain101]

I thought of a couple facts about gravity.

 

Gravity force is related to the density of matter to space ratio.

 

The greater the density of matter in a given vacuum area of space, the stronger the force can be.

 

In the center of earth is an ultra dense core, the main source of the force of gravity we experience here.

 

So if matter can have a maximum density, in such a way that all becomes one, a state of matter beyone our classification of a solid, then it shall have a maximum gravity force.

 

The law of every action has an equall and opposite reaction inspires me to wonder where the opposing action of gravity exists.

 

Could its opposite force be the energy that radiates from all matter?

 

Is this where light and gravity have there zero point exchange?

 

Id like to know if matter can attain a maximum density to space ratio, if there is no room for space, there is no room for light, because space is relentless electromagnetic radiation. If there is no room for space and matter is one, then energy would theoretically not exist in this type of object, absolute rest on the atomic scale? interesting things to ponder.

[Harry Costas]

arkain siad

 

"So if matter can have a maximum density, in such a way that all becomes one, a state of matter beyone our classification of a solid, then it shall have a maximum gravity force."

 

The ultra dense matter in neutron stars and the so called quark stars is as close as you can get to a singularity study.

 

http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?Neutron+stars

http://www.space.com/scienceastronomy/astronomy/new_matter_020410.html

 

In these extreme density matter i think you can get compaction in the order of 10 ^ 18

 

 

As for energy and matter they are one of the same.

[CraigD]

So if matter can have a maximum density, in such a way that all becomes one, a state of matter beyone our classification of a solid, then it shall have a maximum gravity force.

If by “have a maximum gravity force”, you mean “exert the greatest gravitational force on other bodies”, this isn’t true.

 

The most gravitationally important objects in our immediate neighborhood are the Sun, followed by Jupiter, both of which are not much denser on average than water, about 3 times less dense than the Earth, and 9 times less dense than an ordinary lead ball.

 

The density of an object doesn’t figure importantly into the gravitational force it exerts on other objects. The important factors are the central object’s total mass, and the distance to the objects being accelerated. If, for example, the Sun were suddenly to decrease its radius by 50%, giving it a density close to lead, it’s force on the orbiting planets would actually decrease very slightly.

 

What great density does allow is for object to get very close to the central object. The much smaller distance between them then results in a much greater gravitational force. This force can be so great for objects like neutron stars and black holes that it can do things like reduce infalling matter to plasma.

Id like to know if matter can attain a maximum density to space ratio

There’re are several useful “maximum densities” of matter.

 

Atomic matter can’t get much denser than about 10^8 g/cm^3 – 100 million times the density of water. Beyond that, it becomes degenerate – unable to have electrons in atoms, with a density of roughly 10^12 to 10^15 g/cm^3. This is what most stellar astronomers believe “neutron stars” are made of.

 

For densities greater than about 10^15 g/cm^3, theory suggests the quarks in a neutron stop working right. That happens then is not well understood – some believe that the 3 (Up and Down) quarks in each neutron combine, some transforming into Strange quarks, into a kind of single big neutron known as strange matter, with a density of perhaps 10^20 g/cm^3. Others don’t believe strange matter can exists, except perhaps very briefly.

 

That happens for densities greater than 10^20 g/cm^3 is very controversial. Some theories – many of the oldest – allow matter to collapse to a singularity of infinite density. Others don’t. All that theories agree on is that, at such densities, matter becomes very weird.

if there is no room for space, there is no room for light …

By any commonly accepted theory, this isn’t true. Simplifying a bit, matter consists of fermions, light of a kind of bosons called photons. Fermions obey the Pauli exclusion principle, which states (again simplifying a bit) that you can run out of room for them. Bosons don’t – you can never run out of room for them. So – ignoring General Relativity weirdness, which you can as long as you’re not talking about huge masses – while fermions can absorb and emit bosons in many ways, they can’t exclude them by “taking up their space”.

[CraigD]

The speed of Gravity does not equal the speed of light. see links

As the links Harry provides show there are theories in which gravity propagates instantaneously, at the speed of light ©, or somewhere in between. There are even some in which it propogates slower than c.

 

Which theory will prove right is uncertain – otherwise, there wouldn’t be so many competing theories. Most Science professionals, and at least many armatures, including I, favor theories in which it propogates at c – specifically, theories in which the gravitational force is reconciled with the Standard Particle Physics Model with a new boson – the graviton – so, like all bosons, propogates at c.

 

Theory without experiment is incomplete Science. An experiment to determine the speed of gravity isn’t hard to design in principle: rearrange some matter, and determine if the change in gravitational force it exerts on conveniently distant bodies occurs before, at the same instant, or after the light signaling the rearrangement. Our galactic neighborhood is conveniently full of highly visible rearrangement of large amounts of matter, in the form of supernovae. So there are currently several experiments (eg: LIGO) planned to determine the speed of gravity.

 

The major problem with such experiments is that, compared to the other fundamental forces, gravity is very weak per interaction – a staggering 10^25 times weaker than the weak nuclear, and 10^36 times weaker than the familiar, easy-to-measure electromagnetic force. So, even with gigantic events like supernovae, the experimental setup required for such experiments requires unprecedented sensitivity and precision. Getting that sort of sensitivity on the stretchy, rumbly surface of Earth is no easy challenge.

[TheBigDog]

Craig, I read the links from Harry, and it had me pondering. If gravity travels at C, or any speed less than instant, then wouldn't we see an affect upon the orbit of the planets around the sun? And likewise the moon aroung the earth? As the moon orbits thee earth it would be attracted to where the earth had been. As it swings into the path of the earth the cynamics would change compared to when it swings behind. Wouldn't we see a predictable dynamic orbital path that follows the direction of travel of the earth?

 

Bill

[CraigD]

Craig, I read the links from Harry, and it had me pondering. If gravity travels at C, or any speed less than instant, then wouldn't we see an affect upon the orbit of the planets around the sun? And likewise the moon aroung the earth? As the moon orbits thee earth it would be attracted to where the earth had been. As it swings into the path of the earth the cynamics would change compared to when it swings behind. Wouldn't we see a predictable dynamic orbital path that follows the direction of travel of the earth?

This “aberration” argument is one of the simplest and most compelling for gravity being an instantaneous effect-at-a-distance – or, equivalently, a spatial field. A nearly identical argument can be made that magnetic force must also be instantaneous, despite substantial evidence that they are mediated by photons (most arguments for instantaneous gravitational force also argue for instantaneous magnetic force).

 

It relies, however, on an assumption that the mediating bosons are like classical bodies – that they are emitted from the central body containing no more information than their direction, absorbed by the orbiting body, and change its momentum using only this information. If, however, these bosons are permitted to contain information about the momentum of the central body, the aberration can be eliminated.

 

It’s important at this point to note that the particles of Particle Quantum Physics are not actually particles, in a classical mechanical sense. They are, each and every one, a quantum wave function that can be used to determine the probability of a measurement detecting the particle in a particular volume of space at a particular time. The amount of information they contain is greater than that of the classical equation describing the particle’s motion.

 

The Math of quantum wave functions necessary to answer such arguments as the aberration argument is more difficult than the Math required to make it, putting non-specialists like me in the position of having to either accept the simpler argument, or take on faith the validity of its more complicated rebuttal, and describe it in unpleasantly vague and metaphorical ways, as above. :cup: More knowledgeable people do a much better job than I have, and are worth the effort to search out in schools, libraries, or the internet.

 

Note that this is not to say that there are not serious, unresolved problems with current attempt to incorporate gravity into the standard model, just that the aberration argument is not one of them.

[TheBigDog]

More knowledgeable people do a much better job than I have, and are worth the effort to search out in schools, libraries, or the internet.

Don't sell yourself short. You greatly exceed my own knowledge, and explain very clearly indeed.:cup:

 

As soon as things jump into the world of quantum physics I am in deeper water that I currently belong. I read a good book on entanglement (a topic I have yet to see crop up here at Hypography) that had me believeing I understood it, until the first time I tried to explain it, when I was suddenly aware that I was like a monkey doing sign language. That is the only place that I have seen experimental evidence of causality that is instantanious at any distance. I figure gravity has a speed of C that will someday be demonstrated.

 

Bill

[arkain101]

I dont think gravity is a radiant. A radiation.

 

For example, when energy forms into matter, if it radiated outwards sort of like light (containing a speed) The object would be attracted to the closest object in its vacinity, whichever it got to first at C. So For example, if you created matter between sun and earth, and it was about 65% closer to earth, theoreticall the object would sit still untill its gravity reached whatever it needs to work, and it would move towards earth first because it was closer.

 

I find it intriuging that gravity in newtonian physics, is related to the square of one of the radius's. It states obviously gravity is a relationship between two objects. So theres something important underlying there.

 

I also found it interesting that in M-theory of String theory, they discovered the tool of duality in their equations, not just a tool, but a requirement.

As crazy as it sounds I wonder if duality is the fundamental function of the universe. This would mean that everything looks 1/2 the distance away than what it really is, and when you move towards something you both actually move. Which could cause the affect of mass and intertia and force experience. Ke tied to V^2, gravity working on a function of R^2...Energy equaly to mass at C^2.. lol, this is probably wild nonsense.. but high level quantum physics needs it to work with cirtain equations, im not sure if it applies quite in this manner though.

[Harry Costas]

Craigd said

 

"For densities greater than about 10^15 g/cm^3, theory suggests the quarks in a neutron stop working right. That happens then is not well understood – some believe that the 3 (Up and Down) quarks in each neutron combine, some transforming into Strange quarks, into a kind of single big neutron known as strange matter, with a density of perhaps 10^20 g/cm^3. Others don’t believe strange matter can exists, except perhaps very briefly."

 

For quarks to be stable in some form of combination they need special conditions. For now I think they form the neutron which is able to be comapacted because of its neutral charge.

As for a singularity having infinite mass I disagree. The limit will be placed by the properties of the basic particles.

 

Some singularities or Black Holes are about 3 Billion times that of our sun. Eg M87

 

I would even say a few billion more. But! until we have more evidence, it is hear say.

 

The jets that are created by these Black Holes are part of the recycling process. There are discussions that these jets are so big that they even expell ultra dense matter into the surrounding galaxy. These form cores for future star formations. Just an idea for now.

 

If you need links on Black Holes and quarsars let me know.