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Author Topic: If I give an object some potential energy, does its mass increase?  (Read 95347 times)

Offline yor_on

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I don't think so. If I'm right I read it in the papers there? But it's some years ago and when I look on the net I don't seem to find it? But it wouldn't surprise me at all. India and electricity have a very friendly and extremely 'casual relation'. It's only enough with one bright soul to set it up. I think it was 'Vattenfall' that was involved in solving it? I guess they would have had to pay big time if they hadn't solved it too :)
 

Offline Farsight

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...It's all an relation, depending on your choice of reference frame. And that's why I don't see it as the plate having gotten any specific energy from rotating/being lifted.
You gave the plate kinetic energy when you gave it a push this → way. You applied a force for a distance, and accelerated it. It definitely gained energy. However the pendulum string doesn't rob it of any energy. You can twirl a ball on a string and whilst there's considerable force on the string, there's no motion in the direction of the force, so no work is being done. But at the top of the pendulum swing, that kinetic energy has gone and the plate has potential energy instead. Where has it gone? You have to be evidential about this rather than relying on relation. It hasn't gone up the string, and there's no trace of it leaving the plate. So it has to be in the plate. It's quite easy to see where it is. Imagine it's a spinning plate, spinning at the speed of light. It's rigged up with lasers etc to configure a clock. At the top of the swing, the clock runs faster. At the bottom of the swing, the clock runs slower, because of gravitational time dilation. That means the plate must be spinning slower at the bottom. Now think of electron spin instead of an overall spinning plate, then treat this along with all other subatomic motion as your "jiggling", and everything works out neatly. All you have to do is put in a minus sign.   
 

Offline Geezer

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You can twirl a ball on a string and whilst there's considerable force on the string, there's no motion in the direction of the force, so no work is being done. But at the top of the pendulum swing, that kinetic energy has gone and the plate has potential energy instead. Where has it gone? You have to be evidential about this rather than relying on relation. It hasn't gone up the string, and there's no trace of it leaving the plate. So it has to be in the plate. It's quite easy to see where it is.

The energy is not in the plate. It's in the system that comprises the plate, the earth, and the force that tends to accelerate them towards each other.
 

Offline Farsight

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I'm sorry geezer, but when that plate escapes the system, it takes the potential energy away with it. That's proof positive that the energy is in the plate. Try proving otherwise, and you'll find you simply can't. You'll have to resort to a "spring" that simply isn't there, and magical mysterious action-at-a-distance, which even Newton knew was false:

"That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it."

Gravity is a local phenomenum, not an action-at-distance effect. It operates through a local gradient in gμν, just as Einstein described it. Unfortunately very few people read the original General Relativity to understand what Einstein actually said. As an example, in 1916 Einstein wrote Relativity: The Special and General Theory (see http://www.gutenberg.org/etext/5001) where in section 22, the English translation reads:

"In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position".

However when you look at the original German, what he actually said was die Ausbreitungsgeschwindigkeit des Lichtes mit dem Orte variiert. This translates to the speed of light varies with the locality. It's crystal clear he meant speed rather than a vector-quantity velocity, because he was referring to one of the postulates of special relativity - the one that said the speed of light is constant. Once you appreciate this, you get a totally different picture of gravity. Here's an analogy that hopefully conveys how it works: 

Imagine a swimming pool. Every morning you swim from one end to the other in a straight line. In the dead of night I truck in a load of gelatine powder and tip it all down the left hand side. This starts diffusing across the breadth of the pool, imparting a viscosity gradient from left to right. The next morning when you go for your swim, something's not right, and you find that you're veering to the left. If you could see your wake, you'd notice it was curved. That's your curved spacetime, because the pool is the space round a planet, the viscosity gradient is Einstein's non-constant gμν, and you're a photon. As to how the gradient attracts matter, consider a single electron. We can make an electron along with a positron from light, via pair production. Since the electron also has spin, think of it as light trapped in a circular path. So if you're swimming round and round in circles, whenever you're swimming up or down the pool you're veering left. Hence you find yourself working over to the left. That's why things fall down.

Your leftward motion comes out of a reduced rate of sub-atomic circulatory motion or spin. The latter is yor-on's "jiggling". The rate is reduced near the surface of a planet where where gravitational potential is lower. Gravitational time dilation is the clear evidence for this reduced rate of motion, and we see it in for example the GPS clock adjustment. The gμν gradient "veers" internal sub-atomic motion which we call potential energy, into the macroscopic motion which we call kinetic energy. I'm not fooling you about this, and I can give you more Einstein references to support what I'm saying. See for example his 1911 paper "On the Influence of Gravitation on the Propagation of Light" where he says c=c0(1+Φ/c˛). He got this somewhat back to front, but there are examples from 1912, 1913, 1914, and 1915 where you can see his ideas evolving into something wherein gravity is the result of a gradient in c caused in turn by energy "conditioning" the surrounding space. PM me and I'll send you pdf page images if you wish.   

However, I cannot explain why all this, or his Leyden Address, isn't in the text books, or why it is not taught. Perhaps it's something to do with the way people who have been taught that "Einstein told us the speed of light is constant" have difficulty when confronted with the original material that says "Einstein told us the speed of light reduces in line with gravitational potential". Rather than examining the evidence as a rational scientist should, they tend to dismiss it, and thus the myth and mystery persist.     
 

Offline Geezer

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I'm sorry geezer, but when that plate escapes the system, it takes the potential energy away with it.

I think I can see why you are having a problem with this. The plate can never escape the system; the force never goes to zero, it just gets smaller. If the plate can't escape the system, it can't "take the potential energy away with it".

If you remove something from a system, you have just defined a new system. All previous bets are cancelled.
 

Offline VernonNemitz

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Tie your plate to a long string, yor-on, and give it almighty push. You did work on the plate, you gave it kinetic energy. So now it swings up to the top of its arc and pauses momentarily. Now freeze the frame and examine the situation. What happened to that kinetic energy? Where did it go? I'm sure we all agree it was converted into potential energy, but where is it? Did it escape up the string? No. Did it somehow leave the plate and move into the surrounding space, the region we call the gravitational field? We can't detect any experimental evidence for any energy leaving the plate. Besides, we know that if we push a plate away from the earth at 11.2 km/s, it has escape velocity, and takes the potential energy away with it. It has now escaped the earth's gravitational field, so there is no relation any more. There's only one conclusion you can draw from this: the potential energy is in the plate. Yes, "gravity influences the jiggling", but it makes it go slower, not faster. This is the only way the conservation of energy works, and gravitational time dilation is your proof.
I see you haven't learned much from our previous conversation in this Thread.  I had some hope when you wrote this in another message:
No, the mass of the system didn't change. All we've done is redistributed the energy within the system. We haven't changed the energy of the system, and mass is a measure of the energy of the system.
You do realize, don't you, that when we are here on Earth using fossil-fuel energy to do stuff, we are mostly just redistributing energy within the Earthly system?  That includes lifting the plate --the plate is not initially so isolated from the Earth that that enormous part of the system can be ignored!  Which is one reason why the Earth actually ends up with a greater portion of chemical-energy-converted-to-kinetic-energy-converted-to-potential-energy-in-the-form-of-mass, than the plate.
 

Offline yor_on

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Farsight :)

It's about definitions.
As I see it that plate has been removed from a 'force' more or less acting uniformly (as far as I know?) on it, namely gravity. That's why I would expect the jiggling to be less. As a counterexample you might imagine what would happen to that plate if placed between two black holes slowly gravitating, equally trying to 'pull' the plate. Wouldn't you expect the 'jiggling' to become more there?

===
Ah, as seen from the reference frame of the plate naturally.
« Last Edit: 26/01/2010 15:39:44 by yor_on »
 

Offline VernonNemitz

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I'm sorry geezer, but when that plate escapes the system, it takes the potential energy away with it. That's proof positive that the energy is in the plate. Try proving otherwise, and you'll find you simply can't. You'll have to resort to a "spring" that simply isn't there, and magical mysterious action-at-a-distance, which even Newton knew was false:
Tsk, tsk, and Aristotle "knew" that effort always had to be expended to keep something in constant motion.  Whoop-te-do.
"That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it."
"There are more things in Heaven and Earth that are dreamt of in your philosophy."
Gravity is a local phenomenum, not an action-at-distance effect. It operates through a local gradient in gμν, just as Einstein described it. Unfortunately very few people read the original General Relativity to understand what Einstein actually said.
You are wrong, because gravity is an infinite-range phenomenon.  And, if Einstein knew so much, why didn't he end up creating the Grand Unified Field Theory that he wanted?  "It's not what you don't know that hurts [your efforts] so much as what you do know that ain't so."  Specifically, Einstein didn't like certain aspects of Quantum Mechanics, such as the Uncertainty Principle, and, in thinking it was flawed, handicapped himself.
As an example, in 1916 Einstein wrote Relativity: The Special and General Theory (see http://www.gutenberg.org/etext/5001) where in section 22, the English translation reads:
"In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position".

However when you look at the original German, what he actually said was die Ausbreitungsgeschwindigkeit des Lichtes mit dem Orte variiert. This translates to the speed of light varies with the locality. It's crystal clear he meant speed rather than a vector-quantity velocity, because he was referring to one of the postulates of special relativity - the one that said the speed of light is constant. Once you appreciate this, you get a totally different picture of gravity.
Wrong.  No totally different picture needed.  Look up the Law of Refraction.  Whenever the medium changes, through which light passes, its speed and its direction is affected.  Very simple, very consistent, gravity included.  What changes in the "medium" of the vaccum, when gravitational field intensity increases, to cause light to go slower and to curve more?  Simple: the concentration of numbers of virtual gravitons (due to inverse square law), relative to the concentration of all other types of virtual particles in the vacuum.
Here's an analogy that hopefully conveys how it works:  
Imagine a swimming pool. Every morning you swim from one end to the other in a straight line. In the dead of night I truck in a load of gelatine powder and tip it all down the left hand side. This starts diffusing across the breadth of the pool, imparting a viscosity gradient from left to right. The next morning when you go for your swim, something's not right, and you find that you're veering to the left. If you could see your wake, you'd notice it was curved. That's your curved spacetime, because the pool is the space round a planet, the viscosity gradient is Einstein's non-constant gμν, and you're a photon. As to how the gradient attracts matter, consider a single electron. We can make an electron along with a positron from light, via pair production. Since the electron also has spin, think of it as light trapped in a circular path. So if you're swimming round and round in circles, whenever you're swimming up or down the pool you're veering left. Hence you find yourself working over to the left. That's why things fall down.
Pair-production is possible because of the existence of virtual electrons and virtual positrons in the vacuum, with which an appropriate-energy photon can interact.  The great thing about Quantum Mechanics is that it does allow us to have a consistent picture, such that we don't need to invoke geometry to explain gravitation.
Your leftward motion comes out of a reduced rate of sub-atomic circulatory motion or spin. The latter is yor-on's "jiggling". The rate is reduced near the surface of a planet where where gravitational potential is lower. Gravitational time dilation is the clear evidence for this reduced rate of motion, and we see it in for example the GPS clock adjustment. The gμν gradient "veers" internal sub-atomic motion which we call potential energy, into the macroscopic motion which we call kinetic energy. I'm not fooling you about this, and I can give you more Einstein references to support what I'm saying. See for example his 1911 paper "On the Influence of Gravitation on the Propagation of Light" where he says c=c0(1+Φ/c˛). He got this somewhat back to front, but there are examples from 1912, 1913, 1914, and 1915 where you can see his ideas evolving into something wherein gravity is the result of a gradient in c caused in turn by energy "conditioning" the surrounding space. PM me and I'll send you pdf page images if you wish.   
And gravitational time dilation is just as easily explained by QM, in terms of interactions with gravitons.  The more something is spending time interacting with virtual gravitons, the less it is spending time interacting with anything else --and it is those other interactions that we use to measure the passage of Time.  Simple.
However, I cannot explain why all this, or his Leyden Address, isn't in the text books, or why it is not taught. Perhaps it's something to do with the way people who have been taught that "Einstein told us the speed of light is constant" have difficulty when confronted with the original material that says "Einstein told us the speed of light reduces in line with gravitational potential". Rather than examining the evidence as a rational scientist should, they tend to dismiss it, and thus the myth and mystery persist.     
I'm pretty sure the lessened speed of light in a gravity field, relative to empty space, is taught in the advanced classes and other places.  Certainly I found out about it without reading original source material by Einstein.
 

Offline Farsight

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Yor_on: yep, it's about definitions. I wouldn't expect the jiggling to be increased between a couple of black holes. It's time dilated down there, everything's happening slower. But from the reference frame of the plate, like if you were in a black box along with the plate, you can't tell.

Tsk, tsk, and Aristotle "knew" that effort always had to be expended to keep something in constant motion. Whoop-te-do.
There isn't any spring Vernon. I raise a brick, and you can wave your hand underneath it. The spring is just not there. And there's no sign of gravitons either.

You are wrong, because gravity is an infinite-range phenomenon. And, if Einstein knew so much, why didn't he end up creating the Grand Unified Field Theory that he wanted?  "It's not what you don't know that hurts [your efforts] so much as what you do know that ain't so."  Specifically, Einstein didn't like certain aspects of Quantum Mechanics, such as the Uncertainty Principle, and, in thinking it was flawed, handicapped himself.
Yep, it's infinite in range, but things fall down because the local space they're in isn't uniform. Call it curvature or call it a non-constant guv, it doesn't matter. If the space was homogeneous there wouldn't be any detectable gravitational field. Einstein ran out of time, and see http://en.wikipedia.org/wiki/Bohr-Einstein_debates re his stance on quantum mechanics. I'd say he disliked the lack of underlying reality more than anything else.

Wrong. No totally different picture needed. Look up the Law of Refraction.  Whenever the medium changes, through which light passes, its speed and its direction is affected. Very simple, very consistent, gravity included. What changes in the "medium" of the vaccum, when gravitational field intensity increases, to cause light to go slower and to curve more? Simple: the concentration of numbers of virtual gravitons (due to inverse square law), relative to the concentration of all other types of virtual particles in the vacuum.
We have no evidence of virtual gravitons. Einstein talked of inhomogeneous space. According to relativity, what changes is the space itself. 

Pair-production is possible because of the existence of virtual electrons and virtual positrons in the vacuum, with which an appropriate-energy photon can interact.  The great thing about Quantum Mechanics is that it does allow us to have a consistent picture, such that we don't need to invoke geometry to explain gravitation.
You should read . Feynman says they're virtual. Also read [url=http://www.iop.org/EJ/abstract/0295-5075/76/2/189]Evanescent modes are virtual photons by A. A. Stahlhofen et al, Europhys. Lett. 76 189-195, 2006. The geometry is right back in there now. And let's not forget that nobody has succeeded in quantizing gravity.   

And gravitational time dilation is just as easily explained by QM, in terms of interactions with gravitons.  The more something is spending time interacting with virtual gravitons, the less it is spending time interacting with anything else --and it is those other interactions that we use to measure the passage of Time. Simple.
We use light. Atomic clocks employ microwaves, look at the definition of the second. 

I'm pretty sure the lessened speed of light in a gravity field, relative to empty space, is taught in the advanced classes and other places.  Certainly I found out about it without reading original source material by Einstein.
One sometimes finds mention of a reduced coordinate speed, but I'd say what tends to be taught is in line with http://www.desy.de/user/projects/Physics/Relativity/SpeedOfLight/speed_of_light.html. Maybe it would be better to continue this conversation on a thread I started entitled "Is Einstein's general relativity misunderstood?".
« Last Edit: 28/01/2010 12:29:39 by Farsight »
 

Offline yor_on

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"But from the reference frame of the plate, like if you were in a black box along with the plate, you can't tell. "

That's a really good idea Farsight. if I would be right you should be able to tell by the increased jiggling, inside our black box, if the gravity might be higher, as I then would expect it to vary with 'distance' to gravitation.

As you imply here, time will. as seen from the frame of the plate, always have the 'same time as usual' meaning that if that plate ah, looked on his watch, a second would seem a second and all sequences would seem the same inside that black box no matter :) where it was, between black holes or on the moon. But if you think of dropping something inside that black box the situation change, depending on where you are.

Let's say that our brilliant plate :) now would measure a ball being dropped one meter inside that box, using his watch to time it under different gravities. will time and the fall be the same under different gravities. Like a 1G fall take 1.s (according to his watch inside that box)for 1.m and then according to this logic 1000 000G fall then also would take 1.s (according to his watch inside that box, sharing reference frame) falling 1.m?

That is, if I understood your reference correctly?


 

Offline Farsight

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That doesn't work, yor_on. Dropping an object and timing it tells you the steepness of the local gradient in guv, but it doesn't tell you how the guv down by a black hole compares to the guv up in space. You compare them by looking at the gravitational time dilation, and you can't do it locally. You start with two identical clocks. You leave one up in space. You take the other one down near a black hole, hang around for a while, then go back up to space and compare the clock readings. These clocks clock up motion. If they're mechanical clocks they clock up the motion of gears and sprockets. If they're light clocks they clock up the motion of light. If they're jiggle clocks they clock up internal subatomic motion, things like electron spin. It doesn't matter what type of clock you're using, you'll always see that gravitational time dilation, because things move slower in a gravitational field.
 

Offline yor_on

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Well Farsight. Inside that box, being in the same reference frame, you will get different values for gravity. So time and gravity differ to me, which seems to make my idea almost plausible :)

You see, as I saw your idea there you seemed to say that locally time always will be seen as proceeding as usual, which makes sense to me. But time as a concept is not gravity, with gravity not acting the same way as 'times arrow' does even though it is closely correlated, meaning that it will change with gravity.

===

That last one will only make sense from an observers frame of reference, of course. For you, being inside that box, f.ex moving towards the EV (event horizon) of a BH, time will always be the same, working 'as usual'. At no time will you ever notice time becoming 'slower' just because you're accelerating, or finding yourself placed in a BH :)
« Last Edit: 28/01/2010 15:58:25 by yor_on »
 

Offline VernonNemitz

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Tsk, tsk, and Aristotle "knew" that effort always had to be expended to keep something in constant motion. Whoop-te-do.
There isn't any spring Vernon. I raise a brick, and you can wave your hand underneath it. The spring is just not there. And there's no sign of gravitons either.
A worthless analogy.  You can wave your hand between two magnets, also, and there is no sign of a spring or the virtual photons passing between them, that explain the magnetic force between them.  Yet Q.E.D. is the most accurately-measured/verified theory in Physics, despite nobody every directly detecting any virtual photons.

You are wrong, because gravity is an infinite-range phenomenon. And, if Einstein knew so much, why didn't he end up creating the Grand Unified Field Theory that he wanted?  "It's not what you don't know that hurts [your efforts] so much as what you do know that ain't so."  Specifically, Einstein didn't like certain aspects of Quantum Mechanics, such as the Uncertainty Principle, and, in thinking it was flawed, handicapped himself.
Yep, it's infinite in range, but things fall down because the local space they're in isn't uniform. Call it curvature or call it a non-constant guv, it doesn't matter. If the space was homogeneous there wouldn't be any detectable gravitational field.  
I certainly agree with that last statement, but the manner of how space can be inhomogenous is what we are arguing about here.  The Casimir effect is proof enough that empty space can be emptier in some regions than others (emptier of virtual particles, that is).  It should be obvious that if QM can describe gravitation, then the presence of a mass, in the vacuum, will mean that the vacuum now has in it virtual gravitons radiating from mass, in addition to the usual background noise of virtual particles.  There will naturally be an intensity gradient with distance from the mass, too, meaning that space will be inhomogenous in that region.  Therefore we can deduce gravitational effects, equivalent to invoking Geometry (but now consistent with the rest of QM).

Einstein ran out of time, and see http://en.wikipedia.org/wiki/Bohr-Einstein_debates re his stance on quantum mechanics. I'd say he disliked the lack of underlying reality more than anything else.
The effect, though, is that he made no significant effort to include Quantum Mechanics in his thinkings about gravity.  Instead, I get the impression he wanted to use Geometry to explain the other forces.

Wrong. No totally different picture needed. Look up the Law of Refraction.  Whenever the medium changes, through which light passes, its speed and its direction is affected. Very simple, very consistent, gravity included. What changes in the "medium" of the vaccum, when gravitational field intensity increases, to cause light to go slower and to curve more? Simple: the concentration of numbers of virtual gravitons (due to inverse square law), relative to the concentration of all other types of virtual particles in the vacuum.
We have no evidence of virtual gravitons. Einstein talked of inhomogeneous space. According to relativity, what changes is the space itself. 
Again, a worthless argument, like saying in 1990 that planets outside the Solar system can't exist because there was no available evidence for them.

Pair-production is possible because of the existence of virtual electrons and virtual positrons in the vacuum, with which an appropriate-energy photon can interact.  The great thing about Quantum Mechanics is that it does allow us to have a consistent picture, such that we don't need to invoke geometry to explain gravitation.
You should read . Feynman says they're virtual. Also read [url=http://www.iop.org/EJ/abstract/0295-5075/76/2/189]Evanescent modes are virtual photons by A. A. Stahlhofen et al, Europhys. Lett. 76 189-195, 2006. The geometry is right back in there now. And let's not forget that nobody has succeeded in quantizing gravity.
And in 1900 nobody had succeeded in building a heavier-than-air flying machine.  Whoop-te-do, another worthless argument.

And gravitational time dilation is just as easily explained by QM, in terms of interactions with gravitons.  The more something is spending time interacting with virtual gravitons, the less it is spending time interacting with anything else --and it is those other interactions that we use to measure the passage of Time. Simple.
We use light. Atomic clocks employ microwaves, look at the definition of the second. 
You are failing to understand.  Every time-measuring device involves interactions between various components, and all those components are also interacting gravitationally with the Earth (or, say, pick some other source, like if the clock was sitting on a neutron star).  However, these interactions cannot be simultaneous; the whole point of a fundamental "quantum of time" is that exactly one interaction would be possible in that interval.  So, regardless of however-many time-quanta exist during "one second", the important thing to ask is, "What percentage of them are being devoted to gravitational interactions?"  Obviously more would be devoted to that if the clock was sitting on the neutron star, instead of Earth.  Which leaves less time-quanta available for other interactions, between components of the clock, and those are the interactions we rely on to tell us the time.  The net effect is that the clock ticks slower on the star than on Earth, even though the same number time-quanta per second occur in both places.  Even without gravitation, this effect can be seen when we think about interactions with the virtual particles in the vacuum; a fast-moving spaceship will encounter more of them per second than a slow-moving spaceship, and therefore the clock ticks slower on the fast ship.

I'm pretty sure the lessened speed of light in a gravity field, relative to empty space, is taught in the advanced classes and other places.  Certainly I found out about it without reading original source material by Einstein.
One sometimes finds mention of a reduced coordinate speed, but I'd say what tends to be taught is in line with http://www.desy.de/user/projects/Physics/Relativity/SpeedOfLight/speed_of_light.html. Maybe it would be better to continue this conversation on a thread I started entitled "Is Einstein's general relativity misunderstood?".
Nope.  Because our argument is not about GR so much as is about QM, and the ways that QM can be extended to also explain the things that GR explains, thereby making GR irrelevant.  (Not "wrong", because GR is quite good at what it does, but "irrelevant", as in "unnecessary".)
« Last Edit: 28/01/2010 16:39:16 by VernonNemitz »
 

Offline yor_on

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Vernon. If you were the observer to a clock falling toward the event horizon. How would you explain the red shift and 'slowing of time' that clock will express, relative you observing? In form of your 'time quanta', that is.

Will they according to you, become 'more' extending 'times arrow' as the clock moves slower relative your frame, or do you see the time quanta as the same 'amount' as it would be if seen from the same perspective (frame) as that clock falling in?

I'm curious to how you see the concept of time quanta, as a 'predefined even if undefined' amount, or as something that comes into 'work' as needed? And I hope I made some sense asking too :)
« Last Edit: 31/01/2010 16:36:33 by yor_on »
 

Offline yor_on

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Farsight I'm still of two minds in my thought experiment.

"Einstein concluded in one of his papers that a particle's increase in inertial mass due to motion would result in an increase in its gravitational mass"

And we do know that acceleration is equivalent to gravity, and mass :)

And:

---Quote--

Does a particle's relativistic mass increase result in a corresponding increase in the gravity field generated by the particle?

Yes, the particle has an increase in energy (kinetic and mass increase) and under general relativity, it is energy that generates a gravity field, not just rest mass.

Dr. Eric Christian.
Nasa

--End of quote-

Take a look here too Fluids and pressure
 
"One might also ask about the answers to this question if one assumed that one were asking about the mass as it is defined in special relativity rather than the Komar mass. If one assumes that the space-time is nearly Minkowskian, the special relativistic mass exists. In this case, the answer to the first question is still yes, but the second question cannot be answered without even more data. Because the system consisting only of the gas is not an isolated system, its mass is not invariant, and thus depends on the choice of observational frame.

A specific choice of observational frame (such as the rest frame of the system) must be specified in order to answer the second question. If the rest frame of the object is chosen, and special relativistic mass rather than Komar mass is assumed, the answer to the second question becomes yes. This problem illustrates some of the difficulties one faces when talking about the mass of non-isolated systems."

But then against it you might say that we added an potential energy by lifting it, which then is equivalent to an added mass :)

So it's still a question of from where we define it.

The question seems to me to become if you can translate gravity into energy without using a definition of first 'interacting' with something, as the ground f.ex for the release of 'potential energy'?

==

Then again, if you consider gravity to be the geometric twisting of 'SpaceTime' it shouldn't transfer any 'energy', possibly. But 'potential energy' is created just out of those 'twists'?

Awh :)

« Last Edit: 01/02/2010 04:14:38 by yor_on »
 

Offline Farsight

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That's good stuff, yor_on, but IMHO it's simpler than you think. Think about Einstein's 1905 paper. Now start with a container of hot gas up in space and call it your system. It's hot, and it emits infra-red radiation. Wait for the radient energy to dissipate, and once it's cooled down, the gas molecules are moving slower. There's less energy in the system so the system has lost some mass. 

Now start again with another container of hot gas up in space, and instead of letting it cool down, let it fall down. Wait for the kinetic energy to dissipate, and even though the gas is still hot, the gravitational time dilation means the gas molecules are moving slower. There's less energy in the system so the system has lost some mass.
 

Offline yor_on

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Would be nice to be sure on that one :)

I still have some wondering left to do there :) It seems to come down to how you view gravity and its 'interaction' with matter. and there I am of the view that gravity is a geometry, not a force? But then we have VMO:s ending in singularities like super black holes?

I hasn't considered gravity as a 'force' before so I will gratefully accept all links from those seeing it as such :)

It's this elusive 'potential energy' irritating me. It's like an itch for the moment :)

" We seek him here, we seek him there, Those Frenchies seek him everywhere.
Is he in heaven? — Is he in hell? That damned, elusive Pimpernel "

Ah, potential energy that is... Not Pimpernel..
And not only the Frenchies :)
 
 

Offline VernonNemitz

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Vernon. If you were the observer to a clock falling toward the event horizon. How would you explain the red shift and 'slowing of time' that clock will express, relative you observing? In form of your 'time quanta', that is.

Will they according to you, become 'more' extending 'times arrow' as the clock moves slower relative your frame, or do you see the time quanta as the same 'amount' as it would be if seen from the same perspective (frame) as that clock falling in?

I'm curious to how you see the concept of time quanta, as a 'predefined even if undefined' amount, or as something that comes into 'work' as needed? And I hope I made some sense asking too :)
I won't claim that my ideas are fully fleshed out, on this topic.  However, if QM truly can explain everything, then some things need to be true everwhere, like the speed of light in a vacuum, far from any mass, is always the same speed.  That's a primary assumption for Relativity, from which much else logically follows.  Here I will assume that time is quantized and that it has a fixed size, which is described here:  http://www.physlink.com/Education/AskExperts/ae281.cfm?CFID=25253792&CFTOKEN=1591d858dcc3d8ce-89D3AB98-15C5-EE01-B9FC9A191E4C5E40

As I mentioned to Farsight, during one time-quantum only one interaction event should be possible.  It might be a gravitational interaction or an electromagnetic interaction or some other interaction.  The huge number of time-quanta per second allows the appearance of simultaneous interactions (not unlike a computer operating system on a single-core computer that does rapid task-switching, and appears to be doing multiple tasks simultaneously, even though it is actually doing just one thing at a time).  Anyway, it is interactions between components of a clock (any clock!) that we use to determine the passage of time.  Normally there are plenty of "spare" time-quanta for such things as gravitational interactions, such that we don't notice a clock running slower in an ordinary planetary gravitational field.  A very strong field, like that of a neutron star or a black hole (very similar those fields can be! --the escape velocity from a neutron star can easily be 70% of lightspeed) will simply overwhelm the available time-quanta with gravitational interactions, leaving few for interactions between clock-components (or other types of interactions, like those associated with age-ing).  So, the closer you get to the surface of a neutron star, or the event horizon of a black hole, the greater is this effect, and the farther away, the less is this effect.  We can CALL it "time slowing", but perhaps a more accurate way to say it is, "Fewer Universal Clock Cycles are being devoted to the task of running that merely mundane clock."

The red shift of light leaving the vicinity of a black hole doesn't need to have anything special to do with time-quanta.  This is instead straightforward energy conversion from one type (SOME of the photon's content) to another type (potential).  The difference between the blue photon that was created near the black hole, and the red photon we see escaping to outer space, is energy that became potential energy (if the photon was reflected by a mirror back to the black hole, it would gain that energy back, and be exactly as blue when it arrives at its origin, as when it left).
 

Offline Farsight

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I still have some wondering left to do there :) It seems to come down to how you view gravity and its 'interaction' with matter. and there I am of the view that gravity is a geometry, not a force? But then we have VMO:s ending in singularities like super black holes?
It's a bit like Chinatown, yor-on:

Evelyn Mulwray: She's my daughter.
[Gittes slaps Evelyn]
Jake Gittes: I said I want the truth!
Evelyn Mulwray: She's my sister...
[slap]
Evelyn Mulwray: She's my daughter...
[slap]
Evelyn Mulwray: My sister, my daughter.
[More slaps]
Jake Gittes: I said I want the truth!
Evelyn Mulwray: She's my sister AND my daughter!


It's "a geometry", and it's "a force". But it isn't like when you push something. It isn't a force that adds energy to an object. The thing is, electromagnetism is like this too.
 

Offline VernonNemitz

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Farsight, it occurs to me that another reason you are wrong about the plate acquiring significant potential-energy-as-mass relates to the photon I described at the end of my last message here.  The photon would come away from the black hole almost as blue as when it was created, if you were right about where the potential energy goes!  Therefore it is I that am correct; most of the energy that becomes potential, as a small body or photon escapes the gravitational field of a larger body, goes to increasing the mass-energy of the larger body, not the smaller body or photon.  Do remember that the most important thing about General Relativity is that it is about "mass-energy" regardless of form.  You can't have a double-standard, treating the plate one way and the photon another.
« Last Edit: 02/02/2010 10:28:14 by VernonNemitz »
 

Offline yor_on

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Vernon, you seem to seek a time like geometry.

"The escape velocity from a neutron star can easily be 70% of lightspeed) will simply overwhelm the available time-quanta with gravitational interactions, leaving few for interactions between clock-components"

One might say that looking at a 'time quanta'  your way, translated into geometry, that time might have different 'depths'. As I find it more understandable that way than if thinking of that 'quanta' as a equal 'distance' of time, that then somehow would become 'split up' depending on gravitational influences.

If you instead allow it to have a 'depth' to it, you introduce a concept where 'time' if so would have one apparent property that we define as it's arrow moving us along, and then another, more or less 'hidden' property to us, describing the relation between gravity, acceleration, uniform motion, mass, energy and time.

The problem here would then be how to to define that hidden property? As a new 'dimension' perhaps? I'm sort of allergic to 'dimensions' for the moment as I find them poorly proofed experimentally.

Mathematically you will have a plethora of ideas, building on each other, creating one 'manifold' after another. But I still wish we could proof that dimensions are a singular property experimentally, before deciding that our mathematical treatment is the only one existing.

So if not another 'dimension' then what?
That's a really good question I think and to me it seems as an 'emergence'. As such you don't need to treat it as a object with several 'singular properties' which releases a lot of mine inability to understand things :)

As an 'emergence' it will contain a 'whole', just as SpaceTime seems to do when looking at its 'plasticity'. Which still leaves us the reason why we can't 'see' it, but to me that says more about how we view the world than any inability of times arrow (or time) to express itself. It gives us clear indications to how it works but in our need to 'split it down' into its smallest constituents we forget that what we define as 'existing' is limited to what we believe. And our 'beliefs' change constantly nowadays :)

As I see it of course, you might have another view that I missed totally.
 

Offline VernonNemitz

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"The escape velocity from a neutron star can easily be 70% of lightspeed) will simply overwhelm the available time-quanta with gravitational interactions, leaving few for interactions between clock-components"
You quoted out of context. 
"A very strong field, like that of a neutron star or a black hole (very similar those fields can be! --the escape velocity from a neutron star can easily be 70% of lightspeed) will simply overwhelm the available time-quanta with gravitational interactions"
The proper extraction from that is:
"A very strong field, like that of a neutron star or a black hole will simply overwhelm the available time-quanta with gravitational interactions"
The parenthesized part was there merely to explain the similarity between the gravity fields of neutron stars and black holes.

It is sometimes said that "Time is what keeps everything from happening all at once."  Time is about CHANGE.  Ordinary geometry is purely static, not dynamic.  As long as this fundamental distinction exists, I won't be trying to equate Time with another geometric dimension.
 

Offline yor_on

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Sorry if you felt mis quoted there. But now you're losing me Vernon. How do you mean when you write "Time is about CHANGE.  Ordinary geometry is purely static, not dynamic.  As long as this fundamental distinction exists, I won't be trying to equate Time with another geometric dimension."

SpaceTime is no static geometry, not according to me at least?
As for that times arrow is about 'change' or as some say 'events' there is no doubt.
But the question I asked was how you thought about 'changes' taking shorter or longer 'time' to happen depending on your frame of observation.

If you think of time 'changes' and watch that clock (observing it) hang at the event horizon, there are going to be an awful lot of changes happening to you before that clock ever moves a inch :) you will have died long before that. And that was the crux of it to me. How you saw those 'time quanta' as differing between different observations from different 'frames of reference'. The clock tick as usual from its own perspective, but you, the earth and the universe is accelerated and blueshifted, changing at a ever increasing pace as it falls in.

So how do you equate those two observations with your 'time quanta'?
Consider A here as the the minute hand ticking one minute as seen from the frame of the in-falling clock.
Here is 'time quanta A' as seen from the frame of the clock, with its time 'as usual' so to speak
<-A->

Here it is from the perspective of you observing the clock.

<-------------------A------------------->

That 'time quanta', lifted from the perspective of the clock, will now contain a infinite amount of 'changes/events' from your perspective observing. You can travel home to Earth and come back without that clock hand ever moved according to you.

Hope this clarified my question.
« Last Edit: 02/02/2010 23:43:43 by yor_on »
 

Offline VernonNemitz

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SpaceTime is no static geometry, not according to me at least?  As for that times arrow is about 'change' or as some say 'events' there is no doubt.  But the question I asked was how you thought about 'changes' taking shorter or longer 'time' to happen depending on your frame of observation.
I said that my ideas on this topic were not fully fleshed out.  But certainly time is the thing that allows one geometrical arrangement to become a different geometrical arrangement.  One particle can at most have one interaction during one time quantum.  This is not the same thing as saying that one time quantum only allows one interaction in the Universe to take place.  The time quantum affects the entire universe at once; different interactions happen in different locations during that quantum of time.  The type of interaction that each particle engages in, during that quantum of time, depends on the particle's neighbors, not on the time quantum.

If you think of time 'changes' and watch that clock (observing it) hang at the event horizon, there are going to be an awful lot of changes happening to you before that clock ever moves a inch :) you will have died long before that. And that was the crux of it to me. How you saw those 'time quanta' as differing between different observations from different 'frames of reference'. The clock tick as usual from its own perspective, but you, the earth and the universe is accelerated and blueshifted, changing at a ever increasing pace as it falls in.
I don't see any time quantum as being different from any other time quantum.  Each one is the same, Universe-wide.  The interactions that occur, at different places in the universe, depend only on what neighbors each particle is interacting with.
A clock that has no other neighbors will have all its parts interacting only with each other during each time quantum.  A clock with lots of neighbors will have at least some of its parts interacting with those neigbhors, during each time quantum.  The net effect is that the isolated clock runs faster, because it takes more time-quanta for the crowded clock to do the same purely internal interactions as the isolated clock.

So how do you equate those two observations with your 'time quanta'?  Consider A here as the the minute hand ticking one minute as seen from the frame of the in-falling clock.  Here is 'time quanta A' as seen from the frame of the clock, with its time 'as usual' so to speak
<-A->

Here it is from the perspective of you observing the clock.

<-------------------A------------------->

That 'time quanta', lifted from the perspective of the clock, will now contain a infinite amount of 'changes/events' from your perspective observing. You can travel home to Earth and come back without that clock hand ever moved according to you.
No infinity; the available evidence strongly suggests the Universe is finite.  (Example, an infinite universe would be associated with infinite gravitation, and we'd all be in a black hole as a result.)  The reference frames you describe are ignoring the available neighbors, for interacting.  Remember that even a vacuum is full of virtual particles with which interactions can occur, and a speeding reference frame can encounter more of those virtual particles than a stationary reference frame, in any specified number of time quanta (the speeding frame has more neighbors).
 

Offline Farsight

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Farsight, it occurs to me that another reason you are wrong about the plate acquiring significant potential-energy-as-mass relates to the photon I described at the end of my last message here.  The photon would come away from the black hole almost as blue as when it was created, if you were right about where the potential energy goes!  Therefore it is I that am correct; most of the energy that becomes potential, as a small body or photon escapes the gravitational field of a larger body, goes to increasing the mass-energy of the larger body, not the smaller body or photon.  Do remember that the most important thing about General Relativity is that it is about "mass-energy" regardless of form.  You can't have a double-standard, treating the plate one way and the photon another.
I don't treat them differently Vernon. The important  thing is that a photon doesn't actually change energy when it enters a gravitational field. There's no evidence of any energy transfer into the photon via unseen particles, the photon is the only particle there, and we must abide by conservation of energy. Yes, the photon appears to gain energy, for example it's measurably blue-shifted. But the frequency hasn't actually changed. Your measuring devices have, because they're subject to gravitational time dilation. Your clocks run slower, so you see the frequency as increased. It's a little like the way something feels warmer if you're cold.
« Last Edit: 03/02/2010 12:29:49 by Farsight »
 

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