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Offline Geezer

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Is this a new paradox of energy?
« Reply #25 on: 26/02/2011 08:00:54 »
It won't be different. All the kinetic energy of the book will be converted into thermal energy.

If you define the system so that it really captures all of the thermal energy while the book fell, it will precisely equal the energy spent in elevating the book.

If it does not, you'll have to rewrite the laws of energy conservation.
 

Offline yor_on

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Is this a new paradox of energy?
« Reply #26 on: 26/02/2011 09:23:57 »
You're right there :) I assume that you mean a 'closed system' for that though. We can define all interactions as expending some energy, that then, no matter how small, will add, or rather transform, some energy in the 'system' and actually the whole SpaceTime you're in. Do you agree?

I don't know if you're right in that, although it's also about how we should see this 'energy expended' in a interaction. To my eyes 'energy' is just a description of something 'not there' but needed to explain why a transformation can express itself as a 'force' doing work. Looked at that way, assuming that we have a conservation of 'energy', whatever that is thought to be, (would have been better to call it 'conservation of transformation' heh, Alchemy here we come :) You still have to define how this 'energy' find its new state as work done in the final stage. 'Energy' is not measurable, radiation is but the radiation clings out in interacting releasing its work into work done. It would be very nice to find some way to measure 'energy' on its own, not only the interactions transforming 'work' into 'work done'.

But I still withhold that you will find no new 'energy/mass' added to that book :). That's also why we need 'potential energy'.
« Last Edit: 26/02/2011 12:24:50 by yor_on »
 

Offline yor_on

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Is this a new paradox of energy?
« Reply #27 on: 26/02/2011 09:30:49 »
It's like most subjects in physics, looked at from basic we will find that they build on axioms and 'statistics/probability' or 'experience' if you like. That's what we used when we invented 'potential energy', and that's what we used when we invented 'energy'.
==

That is why I speak of compressing a spring as the only way I know of actually proving that something have happened 'energy wise' or as I see it 'mass wise'. Assuming that this have been tested that is :) But I do believe this to be correct, and that's also why I wonder about a Lorentz contraction.
==

Another question is where 'work done' goes ultimately, and if it lose something in the transformation? We say it change but never disappear, still, what did it 'lose' in its transformation? If the ultimate state is radiation? Won't that interact too? And when it interact, doesn't it annihilate?

You might ask yourself what you think to exist when the radiation too have interacted? 'Energy'? Or should I call it 'Work done'? What the he* is it? Not measurable, not defined, existing as a very useful concept, but nothing more as I know.
« Last Edit: 26/02/2011 12:35:54 by yor_on »
 

Offline Geezer

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Is this a new paradox of energy?
« Reply #28 on: 27/02/2011 06:54:14 »

You're right there :) I assume that you mean a 'closed system' for that though.


In thermodynamics you have to define a boundary for the system. It does not have to be closed necessarily. For example, the mass within the system could be changing. However, you do need to be able to quantify what is changing in the system.

In the book case (not the bookcase  ;D) there is no reason for the mass within the system to change, so it could be completely closed.

"Internal energy" and "system" are just simplifying constructs that allow us to model what we are interested by eliminating a lot of stuff that is not relevant to the problem we are trying to solve.

Potential energy produced by elevating the book is just the same as winding up the spring in a clock. The only difference is that the energy happens to be a distortion of space-time rather than distortion of the atomic lattice in a piece of spring steel.
 

Offline McQueen

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Is this a new paradox of energy?
« Reply #29 on: 27/02/2011 09:12:35 »
If you hold the book at arms length, even if you feel you are doing work and there is a perceptible strain on your arms, you are not doing any work because the book remains stationary. If you pick up the book and move it somewhere else you have done work because you have moved it over a distance.
 

Offline yor_on

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« Reply #30 on: 27/02/2011 12:51:50 »
Yep, displacement theory :)
And in neither case the book will weight more, that is have an added 'energy'.

If we want to discus 'energy' and 'gravity' as 'forces' then we should start to look at virtual particles and why we expect them to be more the nearer we get to an EV (Event horizon).

I'll suggest this phenomena will be a direct result of 'space' getting 'folded' the closer you get. Not a result of 'gravity's magnitude' as some magnetic force increasing.

As for thermodynamics relative any other system. They are the same, you always need to define boundaries. Not doing so makes it impossible to 'count' on whatever you are trying to define. Don't mistake this for not being allowed to set a 'boundary' as being open though, you can do so as I did when I stated that the radiation/energy disappear into the Universe. That we found conservation laws makes perfect sense, Without them this universe would be unstable and prone to disappearing, us included.

Those laws I expect to be a 'emergence' too.
 

Offline Geezer

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« Reply #31 on: 27/02/2011 22:18:03 »

And in neither case the book will weight more, that is have an added 'energy'.


It's not the book that has added energy. It's the system that that has added energy, and the book is only one part of that system. When you let the book fall, the Earth is accelerating towards the book while the book is accelerating towards the Earth.
 

Offline yor_on

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Is this a new paradox of energy?
« Reply #32 on: 28/02/2011 00:12:04 »
"Potential energy produced by elevating the book is just the same as winding up the spring in a clock. The only difference is that the energy happens to be a distortion of space-time rather than distortion of the atomic lattice in a piece of spring steel."

Nope :)
 

Offline yor_on

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Is this a new paradox of energy?
« Reply #33 on: 28/02/2011 00:18:10 »
"It's not the book that has added energy. It's the system that that has added energy, and the book is only one part of that system. When you let the book fall, the Earth is accelerating towards the book while the book is accelerating towards the Earth."

Can you tell me what you mean by the system having an 'added energy'?

There is a equilibrium existing, that's what the conservation laws are about. The thing happening in all interactions as I see it are 'transformations', all of them ending with some or all of the 'energy' getting transformed into our idea of 'work done' meaning that we won't be able to use it any more.

So, while we can speak of a object getting an added energy, SpaceTime as a whole always should be in a equilibrium. I'm not sure what your 'system' is here? The only way you can transfer new energy into SpaceTime is by divine intervention :) Well, that and entanglements/tunneling and possibly, virtual pair production involving a EV (Event horizon).
« Last Edit: 28/02/2011 00:39:39 by yor_on »
 

Offline Geezer

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« Reply #34 on: 28/02/2011 01:10:56 »

Can you tell me what you mean by the system having an 'added energy'?


Sure can.

In the case of the clock, the "big hand" appeared and added energy to the system, which, in this case happens to be within the boundaries of the clock.

In the case of the book, the "big hand" appeared and added energy to the system, which, in this case happens to be within the boundaries of the book and the gravitational system that exists between the book and the Moon, Earth, or whatever.

The only difference is that in one case the energy is stored in the distortion of a piece of steel while in the other case the energy is stored in the distortion of space-time.
 

Offline yor_on

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« Reply #35 on: 28/02/2011 01:40:33 »
Seems we have a difference of opinion here Geezer. A 'potential energy' is a definition that change with how you define that system, you can have as many 'potential energy's' you like, simultaneously, just by defining the book relative Earth, or the moon, or a passing meteor, or anything differing, from whatever frame you look at.

As for the 'big hand' :) Okay, i kind'a like that one. But when it comes to comparing doing mechanical work on a spring, winding it up and storing the energy, that also will express itself as a added 'invariant mass' if measured with lifting a book? Nope. It's not the same.

In the case of that same book there is no extra energy stored in any 'distortion'. Whatever distortion that book will create by its invariant mass and possible uniform motion will be the same, the only thing differing being what position it has relative the gravitation at large represented of those objects you define as your system. Although in a real experiment you will find that whatever gravity you measure, in any point of SpaceTime, will be the sum of all gravity existing as gravity has no limits, as shown by inertia.

You might assume though that the closer you are to a gravity well, the more 'deformed' will you be as observed from a far observer, but in that case the distortion will diminish for that same observer as the book is moved from the gravity well.
 

Offline Geezer

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« Reply #36 on: 28/02/2011 03:10:34 »
As for the 'big hand' :) Okay, i kind'a like that one. But when it comes to comparing doing mechanical work on a spring, winding it up and storing the energy, that also will express itself as a added 'invariant mass' if measured with lifting a book? Nope. It's not the same.

Sure is.

If gravitational force is the result of a distortion of space-time, the work that was done in raising the book simply increased that distortion. If space-time is distorted by the position of matter, it acts like a sort of spring because it always tries to return to the least distorted state.

I think you may be neglecting the fact that the book also creates a gravitational well. When the force that is keeping the Earth's gravitational well separate from the book's gravitational well is removed, space-time reverts to its most relaxed state by joining the two wells together.

Of course, the analogy with the spring probably breaks down when you compare the measurable forces compared with distance. It's also interesting to note that the concept of a "gravitational well" employs an assumption that things will fall into a well, so we are using the assumption that gravity causes things to "fall" to prove that there is no such thing as gravity. Hmmmm???

I have only three things to say.
Well, well, well.
« Last Edit: 28/02/2011 04:55:20 by Geezer »
 

Offline yor_on

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« Reply #37 on: 28/02/2011 08:34:45 »
"If space-time is distorted by the position of matter, it acts like a sort of spring because it always tries to return to the least distorted state." That's a really nice idea Geezer, you might assume that if 'gravity' was like our 'virtual particles'. An expression of something we can't really touch, even though we find it coupled to mass, and then imagine a totally empty SpaceTime, without matter. If so, how would gravity express itself, as a 'plane'? And would space then .?

As for the rest, I think we both will exhaust ourselves defending our viewpoints :) the thing I saw questioned was if the book got some added energy/mass by being lifted. I say no, and I think we both agree on that? When it comes to how the energy used by the hand should be defined I say it gets lost into 'space', whereas you think of it as adding to a distortion of sort, if I got it right?

Now, we are of different views there, and, until someone can point us to that definite experiment proving one or another, and I don't mean Monte Python :) we will differ on that.

 

Offline Geezer

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« Reply #38 on: 28/02/2011 21:35:33 »
Well, I would like to disagree with you, but as I'm not sure how you explain what causes the book to fall, it's kind of difficult to disagree. Maybe you could try to explain what happens in your model?
 

Offline yor_on

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« Reply #39 on: 01/03/2011 16:08:29 »
You mean if the book falls of the table? Ignoring the hand then? It will follow a geodesic until it meet a obstacle, like the ground. Are you moving the discussion from if the book had a energy or not, to what happens when/if it falls?

Are you saying gravity is a force containing a energy Geezer?
 

Offline Geezer

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« Reply #40 on: 01/03/2011 18:15:06 »
Are you saying gravity is a force containing a energy Geezer?

No. I'm saying the system which, in this case, consists of the book, the Earth and space-time, causes the book to fall. We can obtain work from that system, so, if you like, there is energy stored in it, but it's not stored in any particular element of the system. It's an interaction between matter and spacetime.

It's the same as the rubber sheet model that demonstrates how the distortion of space-time produces the gravitational effect that keeps bodies in orbits. It also demonstrates how bodies are apparently attracted towards each other.

When you say "follows a geodesic", I'm not sure what that means.
 

Offline yor_on

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« Reply #41 on: 01/03/2011 18:40:46 »
As I see it.

It will follow a geodesic in what you refer to as falling. If standing on Earth we would define it as accelerating too. Though if we were gnomes living inside the book we would not find any gravitation acting upon us, making it inseparable from any other uniform motion, excepting tidal forces. The definition I have on a acceleration is that you will feel 'gravity work/act' upon you. And in the case of the book falling there is nothing acting, as told by our gnomes. It's more like it's 'out of bounds' relative the gravity well and search its equilibrium, well, sort of :)

==

If you define uniform motion as being 'at rest' as there is no way to define any 'speed', you can also say that it already are in a equilibrium, and finally will find that equilibrium disturbed by Earths surface acting upon it, as long as it rests there, squashed or not :)
« Last Edit: 01/03/2011 23:01:07 by yor_on »
 

Offline Geezer

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« Reply #42 on: 01/03/2011 19:26:29 »
I think I'll stick with the rubber sheet  ;D  Gnomes are not to be trusted.
 

Offline yor_on

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« Reply #43 on: 01/03/2011 19:40:16 »
Think of SpaceTime like a topology. If we could color it you would find all those bends twists and curves. The roller coaster tracks to a planet is really 'deep' so the book has only one way to go, its speed 'accelerating' as seen from Earth is no acceleration at all, it's a free fall all the way to the surface. Any acceleration has to act on the object accelerating, creating the equivalent to a 'gravitational force', a weight if you like. Without it, no acceleration exist. Try this one, chapter two and forward.. It seems nice.
 

Offline yor_on

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« Reply #44 on: 01/03/2011 19:57:23 »
The funniest thing with this 'topology' we have, is that all of it are representing 'straight lines', although through 'SpaceTime'. So if we could roll it out on a flat surface? Which we can't really, it would tear up, we would see how it looks in 'reality' :) Although I can't imagine exactly how it would look then, I'm mighty sure that it would look pretty weird. And even though the book to us Earthlings is 'accelerating' it does not expend any energy, neither does it gain any. The thing changing is only its position inside space and time, in the 'topology' as I call it :)

What one can do, and as I think you do too(?) is to define different 'gravitational potentials' to different positions in a 'system', and then state that relative this position the books 'potential energy' relative Earth will be ??, assuming that it would 'fall' from there. It's one way to think of it.
==

In fact, it's close to how I wonder about matter too, if you just let matter be 'spread out' on that flat plane. I've been thinking of it for some time now :) If that isn't how it really is, 'virtuality' included. Think of the explanation to how the Casimir force is thought to 'work' relative its wavelengths. What such an explanation starts with is assuming that those wavelengths matters, and 'classically' they don't, exist I mean. So, what are they? And how can they be excluded from the plate and sphere proving it. Doesn't all matter include 'virtual particles'? It's sort of weird, but interesting.
« Last Edit: 01/03/2011 20:37:28 by yor_on »
 

Offline Geezer

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« Reply #45 on: 01/03/2011 20:52:21 »

Though if we were gnomes living inside the book we would not find any gravitation acting upon us, making it inseparable from any other uniform motion,


Only because you are defining a system that does not include the Earth and space-time. If you define the system to include the Earth, the gnomes, and space-time, which you must if you recognize that the gnomes and Earth get closer together, you will discover that they really are accelerating towards Earth and the Earth is accelerating towards them.

It's like a game of football. If you keep moving the goal posts around, you can always win. It you don't define the boundaries of your system, you can talk yourself in to believing almost anything.
 

Offline yor_on

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« Reply #46 on: 01/03/2011 20:58:13 »
Geezer, that won't work. Either you have a acceleration in that book, then you also have a 'weight' acting on our gnomes. Or you don't have a acceleration at all. Using that definition you also can define 'inertia' as an acceleration, as that is exactly what it is. And the direction of that 'acceleration' have no importance at all. What is important is that either you expend some energy, or something else expend it, acting on you forcing you to break your uniform motion.
« Last Edit: 01/03/2011 21:06:30 by yor_on »
 

Offline Geezer

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« Reply #47 on: 01/03/2011 21:12:36 »
The gnomes are no different from trainee astronauts experiencing "weightlessness" in the Vomit Comet. If the system is confined to the aircraft, they are weightless. If the system includes the Earth, they are accelerating towards it, just as they would if they were not contained within the aircraft.

It's all about boundaries and frames of reference. You can say the gnomes are not accelerating as long as you keep the Earth out of it. But you cannot use an argument that ignores the Earth to prove that they are not accelerating towards the Earth.
 

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« Reply #48 on: 01/03/2011 21:28:15 »
Try this.

Step out of an aeroplane at 20,000 feet. Close your eyes. Keep repeating "Yippee! I am weightless! I can fly anywhere I want to!"

As long as you don't open your eyes, you'll be OK.
 

Offline yor_on

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« Reply #49 on: 01/03/2011 21:28:55 »
Remember how you could define two uniformly moving object, moving relative each other, as any of them using the total 'motion' with the other becoming a 'inertial frame' without motion. This is the same but instead of motion we're discussing gravity. And any uniform motion, including the one seen as a gravitational acceleration when standing on Earth is defined by no 'gravity' perceptible inside a 'black box'. If you can't define the 'gravity' in there it do not exist for you. It is a function of space, matter and time, the 'topology'.
==

To see SpaceTime you will have to accept that both statements above actually is true. If you don't you will have to use Newtons definitions. They work perfectly on Earth, but becomes slightly 'out of sync' with the universe at large
« Last Edit: 01/03/2011 21:34:44 by yor_on »
 

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