Speed of Light Past Event Horizon

Welcome to the wacky world of theoretical physics. You see by stipulating that nothing, not even light, can escape past the event horizon of a black hole one can claim that anything can happen to the occupants inside the black hole.

But Stephen Hawking wrote a famous paper on what is now known as Hawking radiation. My grossly simplified understanding of this paper is that after awhile the amount of matter that gets drawn into a black hole exceeds a critical limit. When this limit happens the amount of matter that tunnels to the other side of the event horizon exceeds the amount of matter that is still entering the black hole. Thus the black hole starts to shrink to nothing existing in the black hole. The added confusing part of this is that spacetime in these gravitational fields get so dramatically distorted that any phenomena that happens at one moment in time in one inertial frame will happen at another time from another frame.

Thanks for the explanations. If I have understood, you've answered my question.

At the point of singularity, the distortion would be so great that the photon path would be normal to that of space-time? So as time became "perpendicular" to the direction of space-time it would slow to the point where it would effectively cease relative to that direction. Speed being a measure of relative movement through space-time, without time there can be no movement. So instead of accelerating it actually stops - in that direction. But if viewed from the "perpendicular" direction it would still be visible at its usual speed.

So, relative to itself it's speed has not increased because of the time distortion? But to an outside observer, it would seem to accelerate?

Or how about this? If viewing it as an x / y graph perpendicular to the plane with x on the plane of your 3 dimensional plane and negative y being the center of the singularity. The trajectory would be an exponential curve. The velocity along the x axis would not change, but as it approaches the singularity and x approaches 0, the velocity along the negative y axis becomes extreme. But to an observer on the plane, the only trajectory visible is the x axis which does not experience a velocity change.

Ok...now for my question about the speed of light.

If speed is a relative term dependent upon a point of reference wouldn't two photons released from opposite stars be traveling at twice the speed of light relative to each other?

Or if I were on a ship traveling at half the speed of light and released a photon behind me just as another ship passed me in the opposite direction at half the speed of light how fast would the photon be traveling relative to the other ship?

Drew

Ok, so we have proven that Einstein was correct, time is not constant (it slows down with respect to the intensity of gravity). Time is also not constant with respect to speed? But the speed of light is a constant (so far), it will bend time to restrict it's speed.

Ok, what about electrons moving around an atom. If they move at the speed of light, does that mean they do not experience time the way the rest of the atom does? Could the life of an electron actually be very small but due to its speed it seems to be eternal?

I apologize if I am asking stupid questions, I don't take college physics until the fall or next year.

Drew

"Ok, what about electrons moving around an atom. If they move at the speed of light, does that mean they do not experience time the way the rest of the atom does?"

People at the physics forums say that electrons don't orbit, yet they have "orbitals".

"I apologize if I am asking stupid questions, I don't take college physics until the fall or next year."

Sorry to tell you, but you won't get answers to your questions there. You may learn somebody's opinion, but you won't learn the truth.

Hi Drew,

The fundamental questions are sometimes the hardest ones to answer. Re electrom moving around an atom. The first point to mention here is that electons do not actualy orbit around an atom the way a satellite does around the earth. If they did they would be constantly accelerating and since an acelerating charge emits electromagnetic radiation they would be constantly losing energy and would quickly spiral into the nucleus. No one actually knows exactly how an electron moves when it is captured around an atomic nucleus as quantum mechanics is somewhat statistical in nature so all we can say is that the electron has a certain energy and has a probability of being in a certain region around the nucleus. In terms of what you were trying to ask, however, I think a better example is that of certain particles (muons) with a very short lifetime (around 10 to power of -6 seconds) created in the ionosphere by collissions with high energy cosmic particles that move at speeds close to the speed of light when they are created. These muons are sometimes detected on the ground even though their lifetime is so short that even if they were travelling at the speed of light they would not make it even a part of the way to the ground before they decayed. The answer is that because they are travelling close to the speed of light their rate of passage of time is slowed relative to an observer on the earth so that their decay time is also slowed down. This is an observable verifyable (look it up on web) example of the time dilation and if the muon was travelling fast enough its decay could be delayed by any finite amount relative to a stationary observer so that it could appear to have a very long lifetime. I hope this answers the intent of your question about the electron and its lifetime while in motion.

Yes, it does answer somewhat. I did indeed forget what my chemistry teacher told me about electron clouds and orbitals.

But it doesn't quite answer the question about the speed they travel. I have a memory of reading something about it being possible to measure the delay of electricity traveling down a wire. If electrons are moving down a wire (from negative to positive) are the electrons that pop out the other end the same ones that went in, or do they swap with electrons in the molecules of the material?

If they swap, I cannot help but think of a wire as a pipe filled with electrons like water, when they move, new ones enter one end, and ones already in, exit the other. If this is the case, wouldn't they be transferring between the orbital clouds and not moving in a straight line?

Could their displacement be less than the actual distance traveled? If so, how fast were they actually going?

My comment on the lifetime of an electron was just a side thought...as you can see by my avatar, my real focus is breaking the speed limit!

Drew

Hi Drew,

If your interest is in fast speeds then you will be dissapointed by the average speed at which electrons move in a current carrying wire (drift velocity) which is usually around a millimetre per second. This should not be confused with the speed at which the electromagnetic field propagates through the wire which is usually close to the speed of light depending on the material. When you switch on a circuit the electric field propagates almost instantly to the other end of the circuit even though the electrons themselves are only crawling along. Note that this is the average speed as the electrons are hopping in and out of the outer orbitals of the atoms in the metal in a chaotic way so that it is not possible to determine the velocity of any individual electron at any given instant in time. This means that the electrons popping out of the end of the wire when you first switch on the circuit are the ones that were within a few millimitres of it and there is no guarantee that any particular electron will make it all the way from one end to the other even if you left the circuit on indefinitely.

An interesting case is for AC distribution lines where the electric field propagates along the wires while the electrons just move back and forth a small distance between cycles never really going anywhere.

Bob

Thanks! I always thought that about A/C current.

Drew

Yes, electrons transfer between orbital clouds all the time. This happens constantly in a molecule that the valence electrons (the electrons in the orbitals involved in chemical bonds) of all of the atoms in a molecule are constantly shared. Now in many molecules the atoms that make up the molecule do not share evenly the electrons. The most important molecule that does this is water. The oxygen in water "holds" the two extra electrons from the Hydrogen more often than the Hydrogen atoms. This makes the neutrally charged water molecule to have a more positively charged side and a more negatively charged side. So a non-ionized water molecule is a dipole.

Now onto electron velocities. Ok this might get a little confusing but the actual velocity of electrons traveling in a current flow (the drift velocity) is considerably less than the speed of light. But the speed of the current is close to the speed of light. The best explanation of this comes from a careful examination of how a Newton's cradle works. This aspect is rarely explained when people notice or play with this toy. Notice the velocity of the falling ball on one side of the chain. When it hits the chain of balls in the cradle this momentum and energy nearly instantly gets transferred to the last ball in the chain which now moves at the original ball's velocity (minus friction and alignment problems). This is what happens when current flows through any material. The falling ball's velocity can be considered the electron drift velocity, while the speed that it took to transfer the energy to the last ball was the current velocity.

Lastly, there are physicists exploring ideas that might permit matter to be moved effectively faster than the speed of light. But this is for now completely theoretical work now that promotes particle physics study experiments. I know of no approved direct experiments to do this.

Good explaination.

gravity is not a force but distortion in the structure of space-time.

A distortion or a component of?

See you are at it again, keep it up, it's very enjoyable! I have a young son that's thrilled with your responses and it makes me happy to know you are one of the few that shares good knowledge.

Thanks again.

jhunter1972

Sorry this was supposed to be under "off subject", my apologies everyone.

Like everything that has to do with relativity, what happens to the photon all depends on your point of view.

Simply put, anything that crosses the event horizon can't be seen from the outside because light can't escape from within it. The photon (or any other matter) still exists within the event horizon ... you just can't see it from outside.

Once the photon crosses the event horizon, it falls or spirals in towards the singularity.

To further complicate things, time dilation affects all matter that falls towards a black hole. As matter accelerates towards the event horizon, relativistic effects come into play so that falling toward the horizon seems to slow down asymptotically as it approaches the it ... seen from far away, it will never reach the horizon; in fact, it will red-shift into invisibility.

And since everything's relative, someone falling toward the horizon would not see himself time-shifted ... he'd just see the horizon approaching as if everything were normal.

So, the state of light or matter within a black hole ... if exists until it enters the singularity, at which point its mass is added to the latter's. A photon's rest mass does not become zero, because in the photon's time frame, it keeps whizzing through space (highly-distorted space, as seen from outside) at the spee dof light.

Cheers! DZ

Note: something inside the event horizon can see outside, but not vice versa. Light from outside can fall into the space bounded by the horizon but no light can get out.

A breif history of time . It's a good read . But in saying that they have found black holes that emit light . Thing always change so the thinking has to change with it .

ok, I am by no means any expert to this thing, but I do have a question. As i understand it. matter does not just disappear, it is merely changed. Solid to liquid to gas. Atoms rearranged to form something else. I am puzzled as to what happens to things inside a black hole? Things cannot simply disappear, or can they? Do they end up in some parallel universe? in in our universe and out to ET.

The short answer is that nobody is completely sure what happens to the matter and light that enters a black hole. The theoretically proposed Bekenstein-Hawking radiation does give a brilliant mechanism for a black hole to naturally evaporate and disappear. With the energy/matter returning to this universe as this radiation. However, this radiation has not been observed. Another theory is that this matter then goes to a white hole elsewhere. The questions then are where are these white holes and what would they look like? One idea is that the white hole exit exists at another location in spacetime. This idea begs the question why we do not see any white holes now? While luck is always a possibility, the more likely idea is that we do not recognize the white holes that already exist. Another idea though is that the white hole is another big bang event that is either recycling the energy/matter back to the original event itself or that the white hole is a new different universe's big bang. I'm sure there are many other theories out there, too. But for now, nobody is really sure.

• http://en.wikipedia.org/wiki/Faster-than-light

• http://en.wikipedia.org/wiki/Photon_sphere

The above links may help. For photons approaching each other I think others have made a good explanation of the closing speeds and relativity. The photon sphere suggests that gravity is very high at the event horizon that the photons are forced in an orbit, we don't see light because its trapped in the orbit about the black hole. I have also read that photons are spit out the other side of a black hole and in essence traveled in time different than ours. Einstein even suggests it may link to time travel. Then there are the tachyons?? Alice in wonder land stuff, curiouser and curiouser.

GA to DrMoose. He seems to have hit the bulls eye on most points.

The URL for the photon sphere was submitted in error with the FTL URL. Check out the new photon sphere

Hi Crendle.

The photons that fall into a black hole are not stationary. Actually they get speeds even greater than c as they approach the singularity. And, of course, very soon they are squashed on the singularity (as everything else that enters the black hole does).

Take a look on this entry http://cr4.globalspec.com/thread/11731 that I made a few years ago. My initial presentation is not correct 100% but, during the discussion that follows, some points are reformed and Jorrie clarifies some issues. I think that you'll find it interesting.

GK ... are you Geokos in the webgame Erepublik?

If so ... lolll ... I'm MZ, Mighty Zontar .. Geia sou, file! :P

Consider that all things falling into a black hole are stretched "spaghetti-fied" into smaller and smaller pieces as they approach the singularity.At some point, they will be broken into the smallest possible elements (strings, anyone?).These strings are emitted out the "other side" and appear in our universe again as pairs of particles.

Matter (concentrated energy) and energy into one side, strings out the other, to reform into matter on this side of the black hole.Death and rebirth.A full cycle.Typical conservtion of natural law at work on a grand scale.These strings are so dense(remember, they were formed in black holes), that space time cannot penetrate them.It can however, go around them.Since all matter is made of these strings, the density of the matter depending on the coppactness of the strings, matter creates a warp in space time, because space has to take a circuitous path through matter, instead of a straight line.There is no such thing as pure matter, except for strings.Every other form of matter has spaces within, and hence are supported by the force field of space time.As the density of the matter increases, it becomes less bouyant, like a ship that is loaded.If it becomes so dense that it exceeds the displacement value of space time, it sinks below the "surface" and becomes a black hole.

This is a very simplist explanation of my theory, but I hope it gets the idea across.

IMHO, and I could be wrong.

HTRN

At some points you are right. [E.g. about the "rebirth" of the energy on the "other side". This other side, though, it is supposed to be (probably) a "white hole", located somewhere in our universe or in another parallel universe or a baby-universe (a cosmic bubble) e.t.c. And it is supposed that this white hole produces pure, reformed energy (apparently from nothing). Also, I like your poetic metaphor about the very dense matter that penetrates -in a way- the space/time continuity and "sink under the surface". In this way a "well" is formed (i.e. a "worm hole") which -probably- ends up on a white hole.] Considering all the other things that you said, it seems that they are not in accordance with the valid science. E.g. the String Theory considers that (some) "strings" are fixed on the space/time membrane (at some points) and oscillate. The several modes of oscillation corresponds to the several subatomic particles. I'm not an "expert" on this field. But you should probably present your thoughts in a physics forum. Then the physicists could show you where (and why) you are wrong.

The very dense matter does not penetrate space-time, any more than a floating ship penetrates the water.Rather, the Space-Time energy field does not penetrate the superdense matter that was ejected by the white hole.I hesitated to use the term white hole in a non physyics forum,but I see that some do recognize it.It is also speculated that some very small black holes exist that emit microwave energy.They are so small that the energy seems to come from "nothing" or nowhere.

The varying vibrational frequencies of the strings could be caused by the conditions on the black hole side of the white hole, such as when fresh matter is injested.There has to be a "full tank" point where the black hole "spits it out" on the other side at the same time it is absorbing matter on the input side, a critical mass point, so to speak.

A small injestion (relatively speaking) would spew out the strings at a slower rate, and a large meal would force strings out at a faster rate, thereby changing the vibration frequency.The frequency, in turn, determines the type of matter formed.

"Spooky action at a distance" could be explained by two ends of a single string, each end in our dimension, and the center of the string outside of our dimension.If you twist one end of the string, the other end twists also.The center of the string is ouside of our dimension, so it is not limited by the speed of light, so the change in the ends of the strings is instantaneous.(the ends being entangled particles).

HTRN

Hello All:

This discussion is complicated enough but I have to ask. Would the analogy hold "true" if we view the photon from its wave nature as opposed to its particle nature?

A particle can be carried by a wave, and exhibit the same characteristics as a wave until stripped from the wave,where it behaves as a particle.

Next question?

You still haven't answered the question. Is the analogy valid or are you at a loss of words?

YES.

I just love precise ambiguity.

HHuummm, So all of these theories about black holes are correct if some of its variables or instances can be proven. With our technology now, and what we actually mathematically know, what is the most likely behaviour in a black hole? (Occam's Razor comes to mind here)

"what is the most likely behaviour in a black hole? (Occam's Razor comes to mind here)"

So the simplest solution is the most likely. What would that be?

From Wikipedia: a black hole has only three independent physical properties: mass, charge, and angular momentum. So the only behavior of a BH is angular momentum. Internally? oblivion.

Check out this news article. Maybe we will get a close up look at a black hole...gulp.

please forgive my ignorance with my next comment, but lets assume that we can prove what a black hole can do or does with matter/energy/time. How would this benefit us as human beings besides our newly found knowledge?

To paraphrase Einstein, what good is a new born baby? We don't know if it will become a Stalin or a Schweitzer. So since we don't know what good a new baby will be should we stop making any?

now how can you argue with that!!!!!

It is interesting to me what the multitude of possibilities in a black hole are. I have seen comments of us trying to find the god particle and what the dire consequences of it are. One comment was that we would create a black hole right on our own back yard. It seems a little far fetched to me, but what are the odds of that happening?

Consider the speed of C to be a boundary, not just of speed, but a definite boundary of our universe, much as the wall of a bubble is the boundary from inside and outside.

Consider the bubble to be fully mirrored on the inside(for purposes of simplicity), and anything moving at or slower than C is reflected back.(The wavelength of the components of the boundary layer are equal to or longer than the wavelength of C).

To exceed the speed of C, and penetrate the boundary, a wavelength longer than or equal to the diameter of the inside dimension of the bubble must be generated.This is quite impossible.

Now mentally redefine the frequency as energy, and you have an analogy of the difficulty of exceeding the speed of light.

There may be bubbles outside of our own, where C is the minimum speed.If an object falls below the minimum speed limit, it goes into a different "bubble" and appears to come from nowhere.

Black holes in our dimension may accellerate primal particles (strings) beyond the speed of C and into another dimension.When they decay, and slow down, (which takes a VERY long time), they "fall" into our dimension.

Thus are the dimensions sorted according to their properties.

I know this is not in agreement with modern physics, but it allows a simpleton such as I to grasp a subject far too complicated otherwise.

I don't think of myself as qualified enough to "grade" your reply, however I can readily visualize it, which is good from my point of view. Question, are you self taught in this subject or formally taught?

Re:

That said, it is sometimes useful to try and visualize things in other dimensions, e.g., the curvature of space into a fictitious extra spatial dimension. This does not mean that such dimensions exist, but if it helps understanding, we should imagine them. We must just be sure that the physics remains sound, i.e., it must not lead to false conclusions.

Exactly!

jhunter

As I understand it, from the point of view of the mathematics of General Relativity, time is a spacial dimension. Granted, it's a little bit different than the three spacial dimensions that we normally work with, but the mathematics treat it as a spacial dimension and admit the possibility of displacement in both directions along the time axis. This is one of the more odd things about General Relativity.

The thing is that General Relativity is about geometry. Specifically, the geometry of the space-time continuum. This is why the visualization I used earlier works so well. Now here's another one.

Remember the earlier visualization, with the three spacial dimensions compressed by one dimension into a flat, infinitely elastic hyper-surface and time being the axis normal to the plane. We place a mass in space-time, however large or small, and it creates a slight distortion, a mass warp. One might call the thing it's gravimetric signature, if we had the technology to detect it.

So, we begin to move our mass. As it moves, it's mass warp obviously has to move along with it. Now, seeing as gravity is not a property of mass as such but rather an effect of the mass warp, it is not reasonable to assume that inertia is also an effect of the mass warp, that what actually resists change in motion is the structure of space-time itself?

Anyway, as our mass moves and it's mass warp moves along with it, let us accelerate the mass. As we approach C, the geometry of the mass warp begins to distort. In the direction of motion, the slope becomes a bit steeper, and behind somewhat flatter until, as we come up against C itself, our kinetic mass becomes so great that the slope of our mass warp begins to look very much like that of a singularity. This by the way agrees very well with what Special Relativity tells us to expect with blue-shift ahead and red-shift behind, and with the time dilation as the local time axis shifts in relation to the local curve of the mass warp.

Now, let us step back a bit and look at the big picture. We have our 4 dimensional continuum, with masses and local distortions and so forth. Does this not remind anyone else of the old concept of the luminiferous ether? Perhaps not in the sense of a substance, but rather of a structure.

And let me suggest something else that is contrary to modern theory. The primary tenant of Relativity, both General and Special, is that there is no privileged frame of reference. However, this suggests to me that the structure of space-time itself, the fabric of the medium, may indeed be that privileged frame of reference, even though it is quite beyond our ability to detect at this time.

I submit that this may be the veriest glimpse of what comes after Relativity.

Since almost all matter has spaces within (except strings), and space time is woven through, like strings thru a sponge.A light ray strikng a different density, like water, will bend.

Likewise with space time.It is warped by matter because it must take a longer path through the matter.These same lines of force (space-time), resist any deformation, like a rubber band being forced tru a small opening.If matter is forced to move,energy is required to force the rubber band thru and it is stretched out behind, and develops a wave that pushes against the object to keep it in motion.A likewise amount of energy is required to overcome the following wave and stop the matter.We call this inertia.The more massive the object, the more intricate the weaving of space time thru the object, and the harder it is to effect a change in state of the object.

DrZeus

I was by no means patting myself on the back. I know my limitations, and this kind of theoretical work is far beyond my meager capabilities. What I am suggesting is that there may very well be a privileged frame of reference, and a true state if rest, one not relative to ones own personal frame of reference but tied to the fabric of the space-time continuum itself. I agree that Relativity is correct in so far as it goes, but I have never believed that Relativity was the last word, nor that our current theoretical framework was complete.

Hi DrMoose, you wrote:

"We place a mass in space-time, however large or small, and it creates a slight distortion, a mass warp. One might call the thing it's gravimetric signature, if we had the technology to detect it."

We do detect this 'gravimetric signature' readily in the Solar system and farther out. Gravity Probe B just did it again, very close to home. The Geodetic effect that it measured accurately, is exactly that signature. The 'anomalous' precession of Mercury's orbit is another example.

The problem with taking the rubber sheet analogy too far is that it is only while accelerating the mass (non-inertially, by applying a real, non-gravitational force to it) that there is any asymmetry in the 'sheet'. Once the acceleration stops, the distortions dissipate away at the speed of light (as gravitational waves, we think) and there is no asymmetry left in the 'sheet of spacetime'. In other words, the mass is again 'stationary relative to its local rubber' and all 'memories of past accelerations' are lost.

This destroys any notion that inertial motion can be absolute and should be measured against a 'privileged frame'. There can only be 'convenient frames'. Near an isolated star, the rest frame of the star is convenient. For the cosmos at large, the frame where the Cosmic Microwave Background temperature is isotropic is convenient. Both may be 'preferred' for the problem at hand, but neither is 'privileged' (in the sense that the laws of physics only hold in them).

Inertia may well be due to this distortion of the spacetime structure when accelerated - not necessarily of the 'rubber', but distortion of an object's own internal spacetime structure. It looks like an object resists changes to its own internal space and time relationships, without bothering about the outside world. It is however difficult to disentangle an object's 'own internal spacetime structure' from the spacetime structure of the cosmos. Objects may just be concentrations of this spacetime structure anyway...

-J

I have always felt that matter is simply a "lump in the gravy "of the space time energy field.E=MC2,which is saying that energy and matter are the same thing,and that matter is simply a concentrated, "non dissolved" form of energy.All the manifestations of solid matter are simply that:There is nothing really solid about matter at all.
On a subatomic level, it is all really energy fields, attracting or repelling other energy fields."Solid" is an illusion.I am not an acosmist, for reality exists in a objective, as well as a subjective manner.We have no choice,however, but to relate to our surroundings subjectively, no matter how hard we try to do otherwise.We would have to have not only an out-of-body experience, but an out-of- existence experience perspective to do so.Our limited senses and intelligence prevent us from grasping the "whole elephant", and like the blind men, we are very apt to be mistaken.But it is fun however to exercise our imagination as far as it will go.

HTRN

Hi HTRN.

Yes, the BB theory says the same thing, as it started out as expanding space with nothing but energy in it. Only when the temperature reduced enough, due to the expansion, did elementary particles of matter congeal out of the energy (the quark-gluon plasma)...

-J

My idea of inertia can be related to a theoretical synchronous motor.

If the rotor and field are rotating at the same speed, no energy is being imparted to the rotor (excluding, for this discussion, fricton, and hysteresis, in all of it's forms).If however the rotor slows down(decelleration) or speeds up(accelleration), energy is required.This energy is what we perceive as inertia, and/or gravity.

Gravity, therefor, can be thought of as an Induced Effect of a change in phase angle between matter and the space-time field. An object in motion stays in motion. An object at rest remains at rest.

The space time field is always in motion in all directions, and matter is always lagging behind, trying to catch up, (analogous to rotor slip).

I hope this analogy is better than some of my other feeble attempts.

IMHO

HTRN (HiTekRedNek)

Hi again HTRN, you wrote: "Gravity, therefor, can be thought of as an Induced Effect of a change in phase angle between matter and the space-time field. An object in motion stays in motion. An object at rest remains at rest."

Interesting, but difficult to imagine. All objects are effectively at rest, because there is no thing like absolute motion. One should only talk about relative motion and it is quite unclear what relative motion between matter and your "space-time field" means (which is not a standard concept, AFAIK).

-J

True, any object can be considered stationary in reference to some frame, but accelleration or decelleration cannot be denied due to the gravity like effect on the object, we call inertia.As a matter of fact,Einstein said that a body in steady acceleration exibits the same exact force as gravity.

IMHO, this is caused by the induced effect on matter generated by breaking the lines of the ("spacetime force field").

This is not a recognized term ,I know, I simply created it for my own edification as a tool to help me comprehend the universe in which I live.

Consider, again, the rotor in a motor .

If the rotor is moving at the exact same speed as the stator field, no magnetic force is generated in the rotor.When the rotor lags, a field proportional to the displacement is induced in the rotor.

Matter lags behind the spacetime field, which is accelerating at the speed of C .The more massive, the more it lags, and the more gravity is induced.

Consider a motor on start up.A high magnetic field is induced into the rotor,and it decreases as the rotor speed come closer to the field speed.Relate this to high mass having more gravity and you may see what I mean.Of course, I am not very good at expressing ideas, but that is the best I can do.

As always, thanks for your feedback, which always make me rethink my ideas, for in the process of explaining them,I gain a more objective insight into them.

HTRN

"True, any object can be considered stationary in reference to some frame, but accelleration or decelleration cannot be denied ..."

Correct - uniform speed is only a relative thing with no absolute meaning. Acceleration is absolute in the sense that you need no reference to detect it. A simple accelerometer can always tell you when you are accelerating (moving non-inertially).

"If the rotor is moving at the exact same speed as the stator field, no magnetic force is generated in the rotor.When the rotor lags, a field proportional to the displacement is induced in the rotor."

I do not think it is a particularly good analogy. There must be relative angular movement between the stator and the rotor. A constant displacement will not produce a field, I think.

"Matter lags behind the spacetime field, which is accelerating at the speed of C .The more massive, the more it lags, and the more gravity is induced."

Something here does not make sense. Why not rather stick to the better analogy of the more massive, the more it distorts the spacetime geometry (the dent in the rubber sheet that DrMoose has described above)? The closer to the mass, the steeper the slope of the dent and the more the gravitational force (if you want to call it a force - it is better to think of it as the acceleration of a particle).

-J

"When the rotor lags" ie; when it is moving slower than the rotating stator field, a magnetic force is induced in the rotor.At synchronized speeds, there is no relative movement between the rotor and stator field, and hence, no induced magnetic force.We are saying the same thing using different words.Matter is always lagging the spacetime field.

The analogy of matter lagging the accelleration of the spacetime field:

Place a bowling ball into a flexible a hammock on a rocket in space.,the balls being held there by a small magnetic field (the balls each have a small iron core). In an adjacent hammock, place a baseball.Now, accelerate the rocket at a rate of 1 G. When the rocket launches,the same amount of acceleration (G force) is applied to both objects, yet the bowling ball sinks deeper into the hammock.This is due to it's higher mass.If the baseball was equal in weight to the bowling ball, it would sink deeper, creating a steeper curve.This conforms to my theory of denser matter distorting spacetime more than less dense matter.

The standard rubber sheet anaolgy relies on gravity to explain gravity.See the irony?

Mine relies only on acceleration, and a difference of speed between the object and the spacetime force field .

All of the energy in the universe is created by this speed differential.The stars are powered by gravity (lagging matter), and possibly dark matter and dark energy also.

If an object could ever catch up with the spacetime field, time would stop,and so would gravity.

IMHO.

Respectfully,

HTRN

Hi HTRN, you wrote: "The standard rubber sheet anaolgy relies on gravity to explain gravity.See the irony?"

Not necessarily: because of the equivalence principle, your accelerated hammocks are equivalent to a gravitational field. One can just as well take the rubber sheet and accelerate it normal to the surface and the results will be the same.

But note that it is not "matter lagging the accelleration of the spacetime field". Your analogy is simply matter resisting being accelerated - the balls lag the hammock, not any spacetime field that I can imagine. Remember that you are in free space, no magnetic field, no gravitational field, etc. There may be quantum fields around, but they do not (yet) feature in gravity or inertia. If/when 'quantum-gravity' enters the stage, I believe that things won't be able to move relative to these fields - they may just be around, like photons... But this is pure speculation.

-J

I am so inept at explaining an ephemeral thought or idea.Very hard to put into a concrete form.I will try again.

Yes, matter resists a change in direction or speed.That is accepted.However, no one knows why this is so.My attempt is to explain a possible reason for this.

Objects can have a stationary spatial relationship with respect to each other, yet still lag behind the spacetime forcefield, because it is moving independently, in all directions.Could we tell if the Earth were accellerating at a speed of 1G,in all directions simultaneously, instead of having a gravity of 1G? The difference between the moon's gravity and the Earth's is due to it's different lag behind the spacetime force field.Lighter objects lag less.

If an object is stationary, in respect to another object, and it begins to accelerate, it is bending the ST forcefield lines more than the non-accellerating object.This bending induces the force that feels like extra gravity.The non accellerating body is still bending the field lines, due to lagging behnd the ST focefield, but not as much as the accellerating object. Likewise on decelleration.Any extra bending of the ST forcefield induces extra "gravity".Since the forcefield exits in all directions simultaneously, direction of accelleration does not matter.Once the object has stopped accellerating, or decellerating, it resumes it's "natural lag" proportional to it's mass.

It is easy for me to see induced voltage in a conductor moving in a magnetic field, or conversly, when the field is moving in relation to the conductor, when it bends the lines of magnetic force.

I see a parallel between all matter and a ST force field that is in "absolute motion" in all directions.Therefore I see gravity as an induced effect of this interaction.

I still do not feel comfortable that I have expressed it properly, but the fault is mine, not yours.

HTRN

Hi HTRN, you wrote:

"The non accellerating body is still bending the field lines, due to lagging behnd the ST focefield, but not as much as the accellerating object. Likewise on decelleration.Any extra bending of the ST forcefield induces extra "gravity".Since the forcefield exits in all directions simultaneously, direction of accelleration does not matter.Once the object has stopped accellerating, or decellerating, it resumes it's "natural lag" proportional to it's mass."

This sounds exactly like Eintein's curved spacetime - no extra theory needed.

"Could we tell if the Earth were accellerating at a speed of 1G,in all directions simultaneously, instead of having a gravity of 1G?"

I think we can surely tell that Earth per se is not being accelerated "in all directions simultaneously". What we can say it that the surface of Earth and everything on it are being accelerated out of their natural spacetime geodesics. Natural spacetime geodesic would have taken the surface to the center of Earth, if it was not for the molecular forces of Earth's material that held it up.

If by "lagging behind the spacetime force field" you mean this acceleration out of the spacetime geodesic, then I agree with you, because that's standard Einstein. In the graphic (right), the arc marked cΔt' is the spacetime geodesic of a free falling item. Such an item experience no measurable force acting upon it, i.e., an accelerometer will measure zero.The point marked CC is the ST geodesic center, around which the ST geodesic curve.

The vertical red line from r_o upwards represents the surface of earth (essentially us) being accelerated 'out of our spacetime geodesics', because we stay at constant spatial distance from the origin (O), the center of mass M. We experience a force pushing us away from the center of M, as any accelerometer will show.

Does this make sense to you? Shout if it does not...

-J

Hi Jorrie,

I don't understand HTRN's explanation nor yours. I agree that the surface of the earth is accelerated toward the center, but have always been puzzled how something can be accelerated without being in motion. Einstein's theory of gravity states that space curves around bodies with mass. He never explained the cause as far as I know. His theory doesn't account for the attraction between two bodies as Newton's formula shows. I have always thought we needed both.

"In the graphic (right), the arc marked cΔt' is the spacetime geodesic of a free falling item. Such an item experience no measurable force acting upon it, i.e., an accelerometer will measure zero.The point marked CC is the ST geodesic center, around which the ST geodesic curve.

The vertical red line from r_o upwards represents the surface of earth (essentially us) being accelerated 'out of our spacetime geodesics', because we stay at constant spatial distance from the origin (O), the center of mass M. We experience a force pushing us away from the center of M, as any accelerometer will show."

In the two paragraphs above I have bolded what appears to be a contradiction. If I stand on the earth with an accelerometer it will measure zero, right?

OK, I'm having some trouble with this. If an object in free-fall has no force on it, what's causing it to move? (F=ma) You would agree that it is being accelerated?

If I tie a ball with a string on my car mirror it acts as an accelerometer (direction only). When I turn left it swings to the right (pointing opposite to the acceleration). When the car is stopped, it points down, (indicating it is accelerated up?). Something doesn't fit. Do you see the dilemma?

-S

Is it because when using the visual of the rubber sheet and marble I get this:

I look at the gravity well image as a graph showing something outside the normal x y z coordinate system. As you approach a gravity well you begin accelerating into this other dimension call it W. If you look at the image where the x axis is the surface of the rubber sheet and a gravity well is centered on the y axis the curve of the rubber sheet is an exponential function much like acceleration. The closer you get to the gravity well the faster you are accelerating in the w direction (which is only lined up with the y axis because we can't draw another.

Drew

Hi S,

Just think equivalence principle. If your car happened to be in free space and there was a rocket attached to its bottom, accelerating it upwards at 1g, you would have experienced the same thing as in a stopped car here on Earth. The string would point 'straight down', not so? The car's g-meter (floor-to-roof accelerometer) would have shown 1g, just like when it stands on Earth. Switch off the rocket (or take away Earth's surface) and the accelerometer will register 0g.

The difficult part is your question: "If an object in free-fall has no force on it, what's causing it to move?" Movement is a coordinate dependent thing. Relative to 'natural coordinates' (spacetime geodesics), the free-falling thing does not move, it just stays on the spacetime geodesic. In 'Earth-centric coordinates', the object moves because there is a 'pseudo force', called gravity. The way it is rigorously treated in physics (without invoking complex geodesic equations) is thus: when you stand on Earth, the only 'real force' that you experience is pushing upwards against your feet. Gravity is a 'pseudo-force', exactly equal and opposite to the 'real force' and hence you stay put in Earth coordinates.

This is similar to a Newtonian treatment of centrifugal forces in rotating systems (rotating coordinates). If your car is rigidly attached near the edge of a rotating platform, the centripetal force on it is 'real', dragging the car around in circles (the string will point somewhat outwards, in the opposite direction to the 'real' force vector). The centrifugal force is 'pseudo', balancing the centripetal force, keeping the car static in platform coordinates. It is only needed when you work in platform coordinates. Likewise the pseudo force of gravity is only needed when you work in Earth coordinates.

Like HTRN, I find it somewhat difficult to explain, so does it make any sense?

-J

I think of a zero reading on an accelerometer during free fall within a 1 G environment as a false zero because the object is accelerating the same direction as the force acting on it. Relative to its original position it is accelerating away from that point, so it is accelerating, it is just that the accelerometer cannot read it because of the direction of travel and force.

It could be the same as if you fired a projectile behind an accelerating rocket at the same acceleration the rocket is going in.

Drew

Hi Drew, you wrote: "I think of a zero reading on an accelerometer during free fall within a 1 G environment as a false zero ..."

Accelerometers measure so-called 'proper acceleration', which is truly zero for a free falling object in vacuum. Proper acceleration is absolute and coordinate independent - it is measured by accelerometers carried by the object in question (just like 'proper time' is measured by the clock of the object in question).

When you wrote: "Relative to its original position it is accelerating away from that point, so it is accelerating,...", you referred to a 'coordinate acceleration', which could have any value you desire, depending on your choice of coordinates. It's somewhat like the speed of a car traveling due east at the equator at 60 mph on its speedometer (earth surface coordinates). In Geocentric coordinates it is traveling at about 1040+60 mph and in Heliocentric coordinates it is traveling at about 67500 mph. One can also pick coordinates at which that same 'moving car' is stationary...

-J

Hi Drew,

Thanks for your comments.

"As you approach a gravity well you begin accelerating into this other dimension call it W."

Interesting theory. Is it yours, or your interpretation of Einstein's?

"I think of a zero reading on an accelerometer during free fall within a 1 G environment as a false zero because the object is accelerating the same direction as the force acting on it."

Let's review Newton's 3 laws.

1st: A body at rest remains at rest, and one moving in a straight line maintains a constant speed and same direction unless it is deflected by a force. (inertia)

2nd: Force = Mass * Acceleration -or- Acceleration = Force / Mass

3rd: For every action force ON an object, there is an equal but opposite force BY the object.

I think we have to conclude there is a force applied to a free-falling object according to Newtons second law. The object is yielding to the force, but it seems for the accelerometer to read zero, there would have to be no friction and no inertia. How is that possible? Is HTRN right about inertia only being a cut of force field lines? What does an accelerometer actually measure? Is it the difference between the action force and the reaction force?

-S

I wouldn't take credit for the theory...just my visualization of what I have read here

We can account for the accelerometers reading of friction with the air, or just visualize the experiment on the moon.

As I understand it free fall can be observed with an accelerometer either in free space outside of a gravity well, or within a gravity well either in orbit or accelerating directly toward the center of gravity. Inertia can be observed in all cases when the object is diverted from either it stationary position (compared to its previous position as T (time) approaches zero) or it is diverted from its orbit or a vector directly toward the center of gravity (at that gravity's acceleration).

Drew

Hi Jorrie,

I understand that gravity is equivalent to acceleration in Einstein's theory. I also understand your centripetal force analogy.

"What we can say it that the surface of Earth and everything on it are being accelerated out of their natural spacetime geodesics. Natural spacetime geodesic would have taken the surface to the center of Earth, if it was not for the molecular forces of Earth's material that held it up."

So you are saying that we are being accelerated away from the earth by the push-back force of the earth's surface? That would fit with the ball hanging from the car mirror. I recall an earlier thread where someone proposed that objects with mass are "sucking up" the fabric of space time. Is that what you are saying here? Is it part of Einstein's theory?

-S

Hi S.

"So you are saying that we are being accelerated away from the earth by the push-back force of the earth's surface?"

Not as strong as "accelerated away from the earth" - we are being accelerated out of our spacetime geodesics by the earth's surface. The spacetime geodesics themselves curve towards Earth's center, which is what your own worldline would do if the surface below you disappears. I would not quite call that "sucking up the fabric of spacetime", but there are certain valid 'Einstein-type' coordinate systems where one can attach such an interpretation and get away with it. I don't think Einstein himself ever used that.

-J

PS: Pardon me for the tendency to write in 'lecturer mode' (e.g. the reference to the equivalence principle) - you don't need that, but it seems to reduce confusion amongst some other readers, I hope.

Jorrie, I understand your graphic illustration, but the question remains:What causes this warp in the space time geodesic?Matter,yes..but how? Changing density between matter and empty space? What has density to do with it if it does not require spacetime to take a longer path than "natural"?How does it bend spacetime? I am not very good at analogies, but I will try one more, that makes sense to me: Consider a transformer.The output voltage will increase as the number of secondary turns increases.(if frequency is constant, and primary is fixed) Consider the output voltage to be gravity.Consider the mass to be the number of turns.Presume that my theoretical Spacetime force field is an oscillating or moving field of constant density and frequency or velocity.Does gravity have a frequency?( If it travels as a wave, it must have.Which begs the question:can we "surf" those waves as a means of propulsion?(( not merely a gravitation slingshot)). More on that later ). As mass (turns) increases, more field lines are bent, and voltage(gravity) increases.A change in direction or speed of an object either increases, or decreases the number of lines bent in a set interval of Time.( inertia, another form of gravity). Perhaps the "Big Bang" produced, and is still producing, a massive spacetime energy field that is expanding and taking all matter with it.(expanding universe?) Eddy currents exist in transformers, perhaps they exist also in the spacetime force field (dark matter?).Eddy currents would be more likely where currents are higher:(galaxies) I will not dispute the space-time curvature, and all of the math that goes with it, and that the concept is visually and mathematically sensible.My only attempt is to parallel these effects with other more commonly understood priciples. Of course, I never claimed to have all of my marbles. HTRN

Here is a link to a quantum computer that solves a problem without ever running.

"Curiouser and curioser said Alice"

http://www.physorg.com/news11087.html

To me, quantum computing is spooky, to say the least!

If quantum mechanics is spooky, and quantum mechanics is real, then reality itself is spooky.

(As Einstein said, "Reality is an illusion, but a very convincing one)

There is evidence that a photon can tunnel thru a solid barrier faster than another photon can travel thru a vacuum. Could this be because the solid is actually a "short cut" thru spacetime, a warpage on a small scale of the spacetime geodesic?

Hi guest, you wrote: "There is evidence that a photon can tunnel thru a solid barrier faster than another photon can travel thru a vacuum."

I don't know about this. Certain quantum effects (e.g. quantum entanglement) apparently have 'faster than light' (ftl) characteristics, but it does not mean it is a single photon going ftl. AFAIK, no experiment has ever been performed (and confirmed) where information transfer happened faster than c.

BTW, if Van Flandern et al were correct, then one could have transferred information ftl by simply shaking a mass 'here' and measure the gravitational effect 'there'.

-J

Hi HTRN,

Science cannot really answer any questions of "why?" - answer one and there will just be next level of why. We know that mass bends spacetime and by how much, but not why...

I keep my sanity by accepting that matter is energy and any non-uniform distribution of energy in space causes a distortion of the space and time in the continuum of spacetime. When you look from the 'outside' of matter, it does not really matter how dense it is, just how much of it there is and how far you are from it. The gravitational potential is proportional to GM/r and the gradient of the potential is proportional to GM/r², the latter being responsible for the 'force of gravity'.

The more readily understood 'mechanism' is that the gradient of the field bends the spacetime worldline (spacetime path) of an object over to the side closer to the gravitating mass; hence the object tends to free-fall towards the mass (as I sketched a few posts ago). That is unless a 'real force' is constraining the object, like the chair pushing against my backside while I'm typing this.

Gravity is a field and as such it is static relative to a mass. If the mass (or its geometry) changes, the change in the field propagates at the speed of light - hence you can't ride those waves. They do pack energy though, but are normally of quite long wavelength (generally from meters to light-years). At close range they can be destructive due to a huge amplitude, but the amplitude diminishes in a linear fashion with distance, just like for EM waves.

-J

"And still, it moves." Galileo, as he was leaving the Inquisition.

And if asked, he would probably have added: "Relative to the Sun"

-J

"Now I see!" said the blind carpenter, as he picked up his hammer and saw.

HTRN

I was using a long wavelength because an antennae element longer than a wavelength reflects the wave, and an element shorter than the wave length passes it forward.Therefor to prevent reflection, the wavelength would have to be longer than the internal dimension of the bubble to exit the bubble.True that higher frequencies have more energy for the same amplitude, but lower frequencies penetrate further.A High Amplitude low frequency wave can also carry (and require) a lot of energy.

Bad analogy, and poor choice of comparison.I failed to illustrate properly what I visualize:

It would take all of the energy in the bubble to exit the bubble is the idea I was trying to impart.

Thanks for your valuable feedback.I will try to be more precise with future analogies.

Hi HTRN and Jorrie,

HTRN, your "spacetime force field" is interesting. I am thinking of Jorrie's cosmic balloon analogy. The fourth physical dimension (not time) has a center. The "spacetime force field" could be emanating from there. This may be a better theory for gravity than inertia? I tend to agree with Jorrie that your lagging rotor analogy is bad because it has a constant speed (not accelerating with reference to the stator).

Jorrie, your argument that his theory is not in accordance with current theory is invalid. We all know that current theory is wrong (or at least incomplete). HTRN is trying to shed some light to give us all new ideas. If we stick dogmatically to the present theories, we will never progress IMHO.

regards,

-S

Re: HTRN is trying to shed some light to give us all new ideas. If we stick dogmatically to the present theories, we will never progress IMHO.

Very much true! That is how we advance, thanks.

Developement of any Theory by Scentific Method:

1 Start with an observation that evokes a question.....

2 Using logic and previous knowledge, state a possible answer, called a Hypothesis.....

And it keeps going from there.

Real scientific theories must be falsifiable. They must be capable of being modified based on new evidence. So-called "theories" based on religion, such as creationism or intelligent design are, therefore, not scientific theories. They are not falsifiable, they don't depend on new evidence, and they do not follow the scientific method.

jhunter

If a gravitational disturbance travels at the speed of light, why is there a difference in the time of maximum solar eclipse and maximum gravitation effect during the eclipse??

Hi guest, you asked: "why is there a difference in the time of maximum solar eclipse and maximum gravitation effect during the eclipse?".

This is precisely what Einstein's General Relativity predicts. The gravitational fields of Earth, Moon and the Sun are 'static' relative to themselves, but they rotate around the barycenter of the Sun/Earth/Moon system. There are no^[1] gravitational waves involved and hence the effect that Earth feels from the Sun/Moon is "instantaneous" - after all, the field (or spacetime curvature) is already 'there'.

If however, something would somehow stop the moon 'dead in its track', that's a disturbance that will propagate at the speed of light. We would experience the gravitational change in position of the moon together with whatever visual effect there might be. This is not anything new - it has been worked out in the late 1920s, AFAIK. It obviously difficult to observe experimentally - how do you stop or deflect a significant mass? It has however been demonstrated to work like this for electromagnetic fields.

-J

Notes: [1] This is not completely true. Although the effect that we measure here on Earth is not gravitational wave related, there are some very, very feeble gravitational waves being radiated outwards from the Sun/Earth/Moon system. It is only when very dense objects like neutron stars or black holes orbit each other at close range that the gravitational waves get strong.

Check out this link that challenges the concept of gravity waves propagating at the speed of light:

http://www.ldolphin.org/vanFlandern/gravityspeed.html.

Hi Guest,

Your "link" didn't work, but this one does. Thank you for the heads up. This is a very interesting read for those who are open minded. Here are a few quotes that I find fascinating:

"For gravitation, this difference of approach has led to two different interpretations of GR: the field interpretation with forces and motions through 3-space; and the 4-dimensional geometric interpretation in which gravity is just geometry without need of forces as such. Einstein and early relativists dealt with both interpretations as if they were interchangeable; but in the context of this paper, we will see that they are not."

"...Feynman preserves the force and motion concepts with their classical meanings, and comments: "It is one of the peculiar aspects of the theory of gravitation, that it has both a field interpretation and a geometrical interpretation. ... the fact is that a spin-two field has this geometrical interpretation: this is not something readily explainable it is just marvelous. The geometrical interpretation is not really necessary or essential to physics."

"In the rubber sheet analogy, if the small target body is at rest on the side of a dent caused by a source mass, it will remain at rest forever until some force acts. The rubber sheet analogy works in our imaginations only because we instinctively imagine gravity under the rubber sheet, with its pull providing a meaning to the concept of downhill. But without pre-existing gravity, the small body has no cause to accelerate, either on the rubber sheet or in the geometrical interpretation of GR. The causality principle is violated."

"The evidence from all six experiments that bear on the question of the speed of gravity is unambiguous in excluding answers as slow as lightspeed. A similar remark applies to the propagation speed of electrodynamic forces. The strongest of these experiments sets a lower limit to the speed of gravity of 2x10¹⁰ c. All objections and questions about this conclusion raised during the last two years have now been addressed and answered. In particular, claims (championed by Steve Carlip) that such a result is inconsistent with general relativity are now shown to be false. Moreover, no serious claim of experimental support for gravity propagating at lightspeed has been advanced in modern times."

"The mere existence of a viable alternative interpretation of the GR equations based on Lorentzian relativity, taken together with the continued experimental viability of LR, mean that the proof of the impossibility of propagation and communication in forward time at arbitrarily high speeds no longer has supportable experimental underpinnings."

-S

Copy the link and paste it and it will work.

No, it doesn't

It did for me when I didn't include the punctuation error of an additional period.

People make typographic and punctuation errors all the time, That's why I like hyperlinking instead for directing people to another web page. You can test the hyperlink in the previewed page before posting the comment.

Hi S, you wrote: "This is a very interesting read for those who are open minded. Here are a few quotes that I find fascinating:"

Fascinating yes, but somewhat missing the point though...

They take the Moon as being "accelerated" in order to stay in its orbit around Earth. In relativity, the Moon simply follows a spacetime geodesic (free-fall) with no forces acting upon it - hence no accelerations. There are only pseudo-forces, which are required in some coordinate systems to make them predict the right results. But then, that's a coordinates choice artifact and nothing 'real'.

-J

Hi Jorrie,

I don't know what point you are referring to. If there is one thing you are, it is predictable. You always endorse "main stream science." My point to you is that there is no doubt that the speed of gravity is at least 2x10¹⁰ c, where you claim it is c. If you will read the article with the many excellent references you will find that the rubber sheet analogy breaks down along with most of what has been considered main stream knowledge. That is about to change, and when it does, you will then endorse it, as you always do. In the mean time you can side with Einstein, but I will side with Feynman any day.

-S

Hi S, but who said that the "the speed of gravity is c"?

As I wrote to Guest above, the field (or the spacetime curvature) is 'just there' and by implication, it has no definable speed. Interpreting that as "the speed of gravity is infinite", is simply wrong - it is only changes in the field that propagate at c (like is the case for an EM field). I know of no experiment that shows otherwise.

BTW, what Feymann said ("that it has both a field interpretation and a geometrical interpretation. ... the fact is that a spin-two field has this geometrical interpretation: this is not something readily explainable: it is just marvelous. The geometrical interpretation is not really necessary or essential to physics") is part and parcel of the mainstream science (you do not think that he disagreed with relativity, do you?)

If I have to choose Einstein and Feynman on the one side or Tom Van Flandern and J.P. Vigier on the other side, the choice is surely predictable...

-J

Hi Jorrie,

"who said that the "the speed of gravity is c"?"

Well, I though you did, but may have been confused as to what you meant. Tom Van Flandern and J.P. Vigier said:

"Because no experimental data suggests that gravity might propagate as slowly as lightspeed c, most of the debate revolves around confusion over the meaning of the expression the speed of gravity. It is undisputed that gravitational waves, assuming these entities exist, must propagate at lightspeed c. However, gravitational waves are still hypothetical, yet are often confused with changes in gravitational fields (force variations). The existence of the latter is firmly established as they are detected daily with gravimeters." Emphasis is my interpretation

You said in the post to the guest:

"There are no^[1] gravitational waves involved and hence the effect that Earth feels from the Sun/Moon is "instantaneous" - after all, the field (or spacetime curvature) is already 'there'."

So they are saying that the speed of gravity is the propagation of the forces (which you don't believe in). It seems that you agree with them on the "results" but not the method. You are using geometrical interpretation (Einstein) and they are using field interpretation (Feynman). It is interesting to note that:

"In both the Newtonian and the GR equation of motion, all quantities take on their instantaneous values for any given time t. No one disputes that Newtonian gravity has infinite propagation speed built in. [11] In GR, one of several ways to get equations of motion is to form a Hamiltonian (an expression for the total energy, potential plus kinetic, for a system of bodies), and take partial derivatives with respect to some chosen coordinates and momenta. In this crucial step for GR, the partials are always taken with respect to instantaneous, rather than retarded, coordinates and momenta, thereby neglecting aberration and implicitly adopting instantaneous gravity. Retarded values are not used because then the equations of motion would no longer conserve angular momentum; i.e., they would be wrong."

No doubt you don't agree with everything they say. This?:

"If angular momentum conservation is invoked in the geometric interpretation to explain experiments, the causality principle is violated. Meanwhile, the field interpretation avoids this problem by allowing faster-than-light propagation in forward time."

"If I have to choose Einstein and Feynman on the one side or Tom Van Flandern and J.P. Vigier on the other side, the choice is surely predictable."

I rest my case.

-S

Hi S, you wrote:

"So they are saying that the speed of gravity is the propagation of the forces (which you don't believe in)."

I thought we had the issue about 'the force of gravity' nailed down some time ago, but it may be that Tom Van Flandern confused the issue again - he is notorious for that. I suppose you know about his un-relativistic views on issues like the operation of the GPS?

"It seems that you agree with them on the "results" but not the method. You are using geometrical interpretation (Einstein) and they are using field interpretation (Feynman)."

I thought I made it clear that the "geometrical interpretation (Einstein) and [the] field interpretation (Feynman)" are equivalent, provided things are done correctly, of course. Both Einstein and Feynman used both, depending on which approach made the problem the easiest to solve. Most scientists still do the same; however, the toughest problems are simpler using the geometric approach.

In any case, like Van Flandern & Vigier (VF&V), we are debating a non-issue here. The reaction of a particle to the gravitational field is instantaneous and everyone agree. Changes in the field propagate at c and it seems that even VF&V agree. Did you notice the statement I made to Guest in my latter post: "BTW, if Van Flandern et al were correct, then one could have transferred information ftl by simply shaking a mass 'here' and measure the gravitational effect 'there'."

Maybe they did not quite state this view, but their article seems to create confusion about it, as for instance their: "If angular momentum conservation is invoked in the geometric interpretation to explain experiments, the causality principle is violated. Meanwhile, the field interpretation avoids this problem by allowing faster-than-light propagation in forward time."

This is a false statement, based on a flawed interpretation of Einstein's field equations, only compatible with their own anti-relativistic views. I have written a little about the relativistic approach in Relativity 4 Engineers, chapter 6 (free download):

Note that the c appearing in the equations has nothing to do with the "speed of gravity"; it is just to express the radial and the transverse velocities of the particle as fractions of c. Conservation of angular momentum means a constant, unchanging situation. Only when something causes a change in that angular momentum does the effect of the change 'ripples away' at c. This is obviously not applicable here.

-J