The energy output of gravity?

[pioneer]

Here is an observation. If you look at the EM, weak and strong nuclear forces, these attract matter in their own ways, give it velocity and output energy as the systems move toward lower force potential. If gravity is a force, what type of energy does gravity output when the system moves toward lower gravitational force potential?

 

Let me rephrase the question with observations. Say we have a cloud of gas, like a nebula. It is so spread out that the GR affects are very small at the very beginning. The falling toward the center of gravity is lowering the gravitational potential within the nebula. This will cause the system wide GR affect to increase. This would suggest, based on other forces, is that a lowered system wide gravity potential will result in higher GR. This lower energy state called higher GR, increases the potential with the remaining mass causing it to fall toward the center of gravity even faster. It is sort of analogous to chilling an ice core more and more causing water to condense faster and faster on the core. In other words, the remaining sparse matter is at the same original energy, only the lower end of the potential (center of gravityand GR) has gotten lower in energy, thereby increasing the attraction potential with the sparse mass.

 

The question is, since the higher GR at the center of gravity implies lower system potential, what kind of energy is being release into the universe. If I was to speculate, since one does not measure any traditional energy output from gravity, and since the goal of lowest gravity potential is a zone of higher GR, then the energy output should have some type of connection to relativity, i.e., virtual energy. Is it possible that the theory of dark matter/energy is describing the virtual energy that outputs from gravity when gravitational potential lowers to create zones of higher GR?

 

I realize this sounds backwards to traditional wisdom but do an energy balance. If higher GR means higher potential that would mean matter gravitating toward higher potential? Where would the energy come from to push matter up the energy hill toward higher potential? Gravity would have to be due to some type of external push that is endothermic. With higher GR at lowest potential, the sparse matter will flow in the direction of lower energy without requiring any assistance but lowering potential.

[BenTheMan]

If gravity is a force, what type of energy does gravity output when the system moves toward lower gravitational force potential?

 

Ummm kinetic energy? [math]T=\frac{1}{2}mv^2[/math].

 

Gravity is really no different at long scales than electromagnetism, other than the numbers are different.

[ydoaPs]

Ummm kinetic energy? [math]T=\frac{1}{2}mv^2[/math].

 

Gravity is really no different at long scales than electromagnetism, other than the numbers are different.

 

Gravity is attractive and repulsive?

[pioneer]

EM force also creates kinetic energy. If two charges attract their kinetic energy will increase. As this occurs, EM energy is given off as the system composed of two charges lowers energy and/or force potential.

 

If we take a cloud of inert gas, subject to gravity, and do an energy balance, its overall gravitational potential energy is highest at the beginning or it would not be able to contract without gaining energy. The result of the attraction will be a lower energy state of the overall system, i.e., GR increasing. Or increasing GR implies lowered potential. If the potential is lowering where is the energy difference going?

[BenTheMan]

Gravity is attractive and repulsive?

 

Clearly this is what I meant.

 

The potentials are both inversely proportional to distance. The forces are incerse squared.

 

I still don't understand what pioneer is confused about. Gravity can be thought of electromagnetism with ``mass'' as the charge. All of the calculations are the same, except you use different numbers.

[swansont]

Kinetic, thermal, electromagnetic. When something contracts gravitatioanlly, things speed up. If you have an ensemble of particles, their temperature will increase and they will radiate more.

 

As with Ben, I don't see this as being a particularly difficult concept. No need to postulate "virtual energy"

[pioneer]

Take this example. We have two masses separated a distance, analogous to say two charges, as you put it. Before the masses touch and heat up due to repulsive forces, gravity potential will still lower. With the EM force, the charges will have motion before they touch and EM style energy will be given off. So if gravity is the same it will have motion (check), but what about the energy given off since the potential of the two mass system have gotten lower.

 

I understand that once one forms a star, or something, one can equate the energy of gravity with heat due to the interaction of the matter in confined space. The energy of interaction, say in the earth, due to gravity, is due to EM repulsion caused by gravity. It is an EM affect caused by gravity confining matter it is not gravity output energy. If there was no EM forces, there would not be the same repulsion heat.

[swansont]

Take this example. We have two masses separated a distance, analogous to say two charges, as you put it. Before the masses touch and heat up due to repulsive forces, gravity potential will still lower. With the EM force, the charges will have motion before they touch and EM style energy will be given off. So if gravity is the same it will have motion (check), but what about the energy given off since the potential of the two mass system have gotten lower.

 

If the masses are moving faster (such that PE + KE is constant), you haven't lost any energy. You can have the system lose energy, as described before, so that the KE is reduced.

 

I understand that once one forms a star, or something, one can equate the energy of gravity with heat due to the interaction of the matter in confined space. The energy of interaction, say in the earth, due to gravity, is due to EM repulsion caused by gravity. It is an EM affect caused by gravity confining matter it is not gravity output energy. If there was no EM forces, there would not be the same repulsion heat.

 

If there were no EM forces things would be very different, but that's immaterial. The energy that was originally gravitational potential energy is converted to other forms.

[fattyjwoods]

i dont get it?

[swansont]

What don't you get?

[someguy]

What does GR stand for?

[BenTheMan]

general relativity

[someguy]

that's what i thought but it didn't make sense to me so i thought it was something else.

 

I still don't really understand.

 

 

if you have a cloud of debris, and the cloud conglomerates into a ball of material in the middle then the forces acted upon the outer debris would be stronger in one direction, rather than weaker in every other direction.

 

"The falling toward the center of gravity is lowering the gravitational potential within the nebula."

 

i don't get this part.

 

i think the gravitational potential of the nebula is always the same. stuff falling into the middle of it just makes it more concentrated and it can be focused all in one direction as compared to a smaller object. to get the same directionality otherwise from the nebula you would need to be bigger and farther away and those things change how strong the pull would be.

 

 

"If we take a cloud of inert gas, subject to gravity, and do an energy balance, its overall gravitational potential energy is highest at the beginning or it would not be able to contract without gaining energy. The result of the attraction will be a lower energy state of the overall system, i.e., GR increasing. Or increasing GR implies lowered potential. If the potential is lowering where is the energy difference going?"

 

actually, i don't know what you mean by overall potential gravitational energy. i don't think the cloud has that, as a cloud. only things in comparison to the cloud. unless you're talking about adding the collective potential energy of every molecule towards each other and then adding it all up. but then you would need to take all of their relative positions into account also.

 

i don't think it is necessary for the potential energy of the system to be highest at the beginning. let's suppose that one object was inside a perfect hollow sphere. it's potential energy would be zero. however, if the hollow sphere around it started to open and retract into half of a sphere kind of like a convertible would open. now there is potential energy and all we changed is the orientation of the matter. a cloud is like this one molecule of the cloud is pulled in all directions and may not have any potential energy or rather it would constantly be fluctuating sometimes at nothing and sometimes at different values in every direction. once a clump gets formed the potential energy for every molecule would be all concentrated in the direction of the clump rather than a light influence from all around. I don't see why there would be a need for extra energy or for unaccounted missing energy. the only thing that changed is the orientation of stuff.

[Jacques]

GR increasing

I don't understand what you mean by that ???

GR is a theory not a propriete of system...

Could you explain?

one molecule of the cloud is pulled in all directions

True, but it will be pulled more in the direction of the center of gravity of the cloud. Potential energy transformed into kinetic energy. On the way toward the center, some collisions will occur and some of the kinetic energy can be transformed into thermal energy, specialy around the center of mass where there will be more molecules. This thermal energy can escape the system in the form of electromagnetic radiation.