What is the Speed of Gravity?

Isn't this how gravity waves are created? Is there a way to calculate the amplitude of the gravity waves generated by the two body (Earth and Moon) system?

You can have gravity wave at velocity of light C in no gravity background. Similarly, velocity of light = C in vacuum is not possible in gravity background. It is very difficult to get gravity free background while vacuum is easily created.

Jorrie, I read your article and I was struck by the fact that gravitational waves carry energy. It made me wonder, can they be absorbed? What I mean to say is that if a binary neutron star system emits gravitational waves of a particular frequency (and energy), could another binary system absorb the wave and have an increase in it's own orbital energy?(an unlikely scenario I know). I'm of course thinking of the electron transitions in atoms and the corresponding electromagnetic waves they emit. Of course, those photons are quantized. I'm guessing the gravity waves are not, so maybe absorbtion can't occur. What do you think?

Thanks Roger. Yes, gravitational waves can be absorbed, but only very weakly so. This is why it is so difficult to directly detect them - so far not even LIGO has been successful. Gravitational waves move right through Earth, but will distort the planet ever so slightly and thus impart some energy on us.

I guess if we could construct a binary system not too far from a radiating binary pulsar, some orbital energy could be transferred, but one will probably have to 'tune the orbital frequencies' for resonance. As far as the Moon/Earth system goes, the gravitational waves radiated are probably extremely (vanishingly) small. I'm not even sure how to calculate it.

Good one. This reminds me of the old joke – the speed of dark must be faster then the speed of light, because no matter how fast light is, the dark is always there first.

I'm only an engineering student, so I may be way out of wack here but can forces have speed? From what I know, gravity is a force, F=m1m2G/r^2, if I remember the equation right. Doesn't this mean that as long as the body orbiting the gravitational body doesn't surpass the gravitational force of the body, it will stay orbiting it?

You are welcome to this forum! Your question: "Doesn't this mean that as long as the body orbiting the gravitational body doesn't surpass the gravitational force of the body, it will stay orbiting it?" is not very clear. Perhaps you can restate it.

A force by itself cannot really have speed; it is the change in a force that propagates at finite speed, always less than c. Think of a very long, stationary metal rod. Push at the one of the rod in a lengthwise direction. Will the effect of your push be observed at the other end of the rod simultaneously with the push?

Interesting.

Conventionally, we've thought of gravity as analogous to your rod... but only if we think of the rod in a limited, simple way. In the real world the rod has mass and elasticity, hysteresis, etc. So, of course, when you push on one end the effect does not show up at the other end until some time later. If we give the end of the rod a whack with a hammer, the rod rings -- so clearly the change in force propagates as a wave.

Neverthless, I don't like to think of "gravity" as having a speed associated with it, although the effects of gravity apparently do.

In a way, all this seems rather messy, does it not? The universe seems, on the one hand, organized in the simplest possible ways (E=MC^2, not E+MC^2.0034 + K). But on the other hand, there are all these apparent complexities. I long to think that when you push on the end of the rod, that yes, the force is transmitted instantly -- faster than the speed of light. But my thinking, while romantic, is flawed.

As I am no physicist I may be well out of kilter here, but it occurs to me that "if" gravity moves in waves then surely +/- oscilation must take place as in alternating current. At the point of zero effect in the sine wave we have no gravity. Do we have the seed of an idea for a form of drive or propulsion i.e a rotating gravitational field ???

Quoting exemmet: "... but it occurs to me that "if" gravity moves in waves then surely +/- oscilation must take place as in alternating current."

Remember that it is not gravity itself that 'moves in waves', but essentially only certain periodic changes in the gravitational field that do. These ripples in the gravity field are quite hard to generate - you need very fast moving massive objects.

In a loose sense, forces have speed. Techniquely, it's fields that have momentum. For instance, Electromagnetic fields have momentum equal to Eo(EXB).

Take a look at the explanation below (You can skip directly to the explanation of momentum at the bottom of page 5.

http://www.phy.duke.edu/~lee/P54/energy.pdf#search =%22electromagnetic%20field%20momentum%22/

Yep Roger, I suppose in a loose sense one can say that the force that starts the domino blocks falling over is propagating down the line at speed x! In the case of e-m transmission, isn't it more the energy that propagates, with the momentum and resultant force only present when the photon is absorbed?

Jorrie wrote "In the case of e-m transmission, isn't it more the energy that propagates, with the momentum and resultant force only present when the photon is absorbed?"

As I understand it, no, although momentum of a electromagnetic field is proportional to the Poynting vector which is energy flux. Although photons are propagating electronmagnetic fields, moving electric fields (which generate and magnetic field), for example, a point charge moving through space, also have momentum. The equation is:

P=S/c^2, that is, the Poynting Vector divided by the speed of light in a vacuum squared (I can't wait till this forum has equation editor) is the momentum of an electromagnetic field.

Quoting Roger: "P=S/c^2, that is, the Poynting Vector divided by the speed of light in a vacuum squared ... is the momentum of an electromagnetic field."

OK, I buy that - the momentum is propagating. But force? I feel force only manifests itself when the momentum is transferred to something. But I guess this is simply semantics, so who cares?

No, you may have a point, I'm not sure. The Electromagnetic force is equal to:

F=(qE+(qVxB)) So if a point charge instantaneously appears out of no where, it immediately interacts with whatever fields are present. Does that mean we can say the force has velocity, probably not, I'm not sure.

Since gravity is the opposite of comedy, wouldn't the speed be inversly proportional? (or is it perversly proportional, I forget the difference) Sorry, bad joke!

I am insane here but... I have a different view of things than the traditional ways. To me, gravity, inertia, and centrifugal force, and probably others of similar nature, have the same cause, source, or nature. I believe that they are a result of quantum effects, which create time itself, and these 'forces' are a lag effect of the a quantum jump 'forward, and then back, but not to the same 'time' which actually creates time. consequently, these forces can not be seen to be moving faster than light. The only thing that moves faster than light is a quantum jump, which has the potential to be instantaneous.(although there are those who will disagree with this) With regards to quantum mechanics, it is based on geometry. (sacred geometry if you will) and mechanics can never be truly understood, without understanding that time itself is where energy comes from, in my opinion. (energy arises from geometric temporal differentiation in geometrically quantized units, and jumping in geometrically defined values, or to geometric intersections, much like chinese checkers. When a fundamental jump occurs in time, the rest of the uniform time field tries to re-balance the field (entropy) and can't, because the 'difference' is now at a different time; not location. thus, energy arises, and remains. It could be said that energy can't be destroyed, because it can't find its way back in time, along the specific geometric path that which defines it. Matter is a more advanced geometric puzzle of quantized energy. What we call particles, are a geometric spin, and as such, store energy in their spinning, like a flywheel. The particles have a natural frequency because of their inherent time geometry. I think motion as we tradionally think of it, is universally impossible, and is an appearance of quantum motion, where energy jumps from location to location instantateously, but with a timeout between jumps. Inertia is a quantized accumulation of energy required to cause a single fundamental particle or unit of time to jump one geometric distance. Because particles typically belong to bodies, the whole body must harmonize geometrically in order to jump, and the energy required is a geometric value representing the same quantity as a single particle, but multiplied harmonically to be proportional to the body in question. When energy is created by a geometric differentiation in time, it also creates a corresponding geometric distortion in space. This is gravity. I do not think gravity waves exist as we normally think of waves, as I think motion is fundamentally impossible. (we live in a quantum universe) If gravity moves, it does so as an apparent motion of quantum energies and matter, and would be related to a temporal source or cause. I don't think we will ever see gravity at a location different than matter, but if we do, it will be at a temporal distortion location, and we will then see the creation of energy at the same time. just my view of things.

Gee-whiz, chrisg288, this is an interesting post, but utterly impossible to read!

Until we have that 'wysiwyg' forum engine that Chris Leonard is promising, a few BR (for Break) HTML commands could have nicely broken your post into paragraphs - see the list 'Allowed HTML'; you have to put sharp brackets around the BR.

If this sounds too technical, try re-posting it on Thursday this week (as Chris promised) - I would love to read it!

Sorry... trying again,... Can't find that article though...thx.

This will sound crazy, but To me, gravity, inertia, and centrifugal force, and probably others of similar nature, have the same cause, source, or nature. I believe that they are a result of quantum effects, which create time itself, and these 'forces' are a lag effect of the a quantum jump 'forward, and then back, but not to the same 'time' which actually creates time.

consequently, these forces can not be seen to be moving faster than light. The only thing that moves faster than light is a quantum jump, which has the potential to be instantaneous.(although there are those who will disagree with this) With regards to quantum mechanics, it is based on geometry. (sacred geometry if you will) and mechanics can never be truly understood, without understanding that time itself is where energy comes from, in my opinion.

energy arises from geometric temporal differentiation in geometrically quantized units, and jumping in geometrically defined values, or to geometric intersections, much like chinese checkers. When a fundamental jump occurs in time, the rest of the uniform time field tries to re-balance the field (entropy) and can't, because the 'difference' is now at a different time; not location. thus, energy arises, and remains. It could be said that energy can't be destroyed, because it can't find its way back in time, along the specific geometric path that which defines it.

Matter is a more advanced geometric puzzle of quantized energy. What we call particles, are a geometric spin, and as such, store energy in their spinning, like a flywheel. The particles have a natural frequency because of their inherent time geometry. I think motion as we tradionally think of it, is universally impossible, and is an appearance of quantum motion, where energy jumps from location to location instantateously, but with a timeout between jumps.

Inertia is a quantized accumulation of energy required to cause a single fundamental particle or unit of time to jump one geometric distance. Because particles typically belong to bodies, the whole body must harmonize geometrically in order to jump, and the energy required is a geometric value representing the same quantity as a single particle, but multiplied harmonically to be proportional to the body in question.

When energy is created by a geometric differentiation in time, it also creates a corresponding geometric distortion in space. This is gravity. I do not think gravity waves exist as we normally think of waves, as I think motion is fundamentally impossible. (we live in a quantum universe) If gravity moves, it does so as an apparent motion of quantum energies and matter, and would be related to a temporal source or cause. I don't think we will ever see gravity at a location different than matter, but if we do, it will be at a temporal distortion location, and we will then see the creation of energy at the same time.

just my view of things.

Thanks chrisg288, it's very readable now! Interesting - is this a personal theory, or is it backed by some mainstream quantum physics?

The mainstream view on gravity is that it is a 'distortion' of space-time, not just of space. Gravitational waves are thought to be ripples in this 'distorted' space-time and they propagate at the speed of light.

Jorrie1273,

When I have "Believe" as one of the variables in my discussion, it may not be mainstream.. :)

That being said, I am trying to find a visual for what quantum geometry looks like. Like everyone else, I seek to understand, and no one has all the answers.

I agree with your definition of gravity, but 'exactly' how and why it is like that... I'm curious.

"When a fundamental jump occurs in time, the rest of the uniform time field tries to re-balance the field" So that seems to imply that you believe time is also quantum, not continuous. What then would be the fundamental unit of time? What is between these quantum time jumps? Instead of a "uniform time field" your theory seems to require a variable period, from instantaneous to 1 full time quanta, during which the gravitational-inertial impulse develops and propagates. A duty cycle if you will. Instantaneous for those space/time intersections involving little or no force, and up to 1 full time quanta for those intersections involved heavilly. This is certainly in truth faster than C and slower than instantaneous, but being perceivable only at the space/time boundries indistinguishable.

I do believe time is quantum. In fact, the driver of quantization. It is the source. Not only is it quantum but has a fundamental nature in which it embodies all polygonal geometrical matrices. (a pentagonal is a different matrix than a hexagonal)

I don't believe you can just slice time, for a fundamental unit. It is a geometric difference of potential. I see a fishtank of 'time' fluid, in a primordial singular state.... and static. "Sametime, sameplace" throughout..... then, a disturbance of unknown origin, or the continuation of a previous impulse occurs. A start point for analytical purposes.

This disturbance wants to cause something, but this primary fluid can't move, can't do anything, except it has the potential to start a new universe, geometrically... so it does. an identical photocopy.. but in making this quantum leap, it has created a further difference of potential. Two things cannot occupy the same space, and so it must be differentiated from the original, in time, or in space, or both. (I don't know if a new universe is created at this point, or if its potential is fulfilled by this event.) (Does anybody have a definition for a universe?)

It is a geometric derivation of the original impulse. It follows the paths of a geometric matrix. A pentagon is laid out on a different matrix than a hexagon, or a square. All prime numbers have their own n-gon geometric. and the same is true when applied to 3D space.

The second state is where there is this differentiation of time, and an entropic energy to return to the initial balanced state. Again, the spacial scenario is static, and so a quantum jump is required. When this event occurs, the change of state is a universal mirror to the original jump, and can be seen as the antithesis of the original. or the 'antiquantum'

The same geometric principles can be applied for the different geometric 'scales' of the universe. A quantum is a geometric fudamental harmonic of the atomic and subatomic particles. Only at the larger scales do things appear to move in a linear fashion, rather than a geometric fashion.

Quoting Anonymous Coward: "So that seems to imply that you believe time is also quantum, not continuous. What then would be the fundamental unit of time?".

Without quite agreeing with chrisg288's view, the fundamental unit of time is Planck time, normally rounded to 10^(-43) seconds. I don't think chrisg288 would have the same limit in mind...

Actually, I do think that the planck constant is at least an aspect of this fundamental measurement. If I recall correctly, this value was plugged in to make plancks calculations accurate to observations. It was just a number, which seemed to be a constant.

This idea sounds a lot like the theory of Loop Quantum Gravity.

Jorrie,

As a physicist, I am just a layman, although I have had courses in University Physics and Mathematics, so I understand some of the principles. I even followed the discussion you had with Roger Pink at the beginning of this thread. However, this exchange with Chrisg288 has me reeling.

Is there really a scientific or mathematical basis for the gobbledygoop he is spouting or is this just some slapping together of pseudo-science and philosophy and throwing it into a blender at warp speed to see what will come out? It almost sounds like he has been watching too many Star Trek or Stargate shows (actually favorites of mine) that might take a few liberties now and then with applied physics, and mixed them up with some New Age philosophy, with maybe a dash of recreational drugs in the mix as well.

Or is it just me?

Quoting STL: "Or is it just me?" Rest assured, it also bothers me!

Chrisg288 has some non-mainstream ideas that I do not agree with, but I'm reluctant to dismiss them as "gobbledygook". Einstein's early work was also dismissed like that - to the detriment of those that did!

I do not believe laymen in science (even engineers) should attempt to redefine physics - lets leave that to the physicists; there are enough of them around! So I try to stick to interpreting mainstream physics in engineering terms.

I comment easily on relativity and cosmology, because they are a passion of mine. Quantum physics I tend to leave to others...