OT: The 10th Demention

[Atrocities]

One of the best examples of what dimensions are and the basic principle of string theory. The Tenth Dimension (http://video.google.com/videoplay?docid=4280922161474483340&q=The+Tenth+Di mension&hl=en)

Based on this I wonder if it would be possible to ever invent something called a Dimensional Drive?

[GuyOfDoom]

Wow, physicists I tell ya are the craziest people.

[Randallw]

That video has been lifted from a flash presenatation at the books website

http://www.tenthdimension.com/flash2.php

I discovered it at least 6 months ago.

[AngleWyrm]

Saw another crazy theory, The Final Theory of Everything (Expansion Theory) (http://www.thefinaltheory.com/?gclid=CNK22_e1lIsCFRJMYQodrwNYRA), in which the author figures all matter is expanding, and explains gravity as just g-forces from the Earth's rapid expansion.

So how long have we got until the sun, moon, stars, and earth all bump into each other...

[capnq]

There's a "popular science" book called The Trouble with Physics (http://www.thetroublewithphysics.com/) which argues that string theory is a seriously flawed dead end that's sucking attention away from more promising alternatives.

[GuyOfDoom]

capnq said:
There's a "popular science" book called The Trouble with Physics (http://www.thetroublewithphysics.com/) which argues that string theory is a seriously flawed dead end that's sucking attention away from more promising alternatives.



I've gotten the impression from some of your posts that you don't seem to be a big fan of science in general.

[Raapys]

I read the free first chapter of The Final Theory. It does bring up alot of valid points about the flawed theories we've built today's scientific knowledge on. The first chapter just explains the errors in current theories, without offering any new ones, so I'm actually considering buying it now, to read his replacement theory.

[GuyOfDoom]

Raapys said:
It does bring up alot of valid points about the flawed theories we've built today's scientific knowledge on.



I'd be curious to know what it thinks those are.

[Raapys]

The link for the first free chapter is here.

http://www.thefinaltheory.com/viewchapter.html

[GuyOfDoom]

The only point I get out of that chapter is exactly what anyone who's in science should know. What we know is only our best approximation with the information that we currently have.

That doesn't mean we're totally wrong, we just don't know enough yet.

[Azselendor]

GuyOfDoom said:
That doesn't mean we're totally wrong, we just don't know enough yet.



Which, in itself, is a good reason to help promote the sciences. We need to know more.

[Phoenix-D]

Anything that proposes to replace -everything- sets off all sorts of alarm bells. You have to have one hell of a weight of evidence for that to work.

Well, this is fun. He's setting off the bull**** detectors left and right even discounting that (example- if protons naturally cluster in the nucleus and are stable, why the !%@ do high-proton count atoms become unstable? Example 2: he doesn't get why we don't use Einstein's theories- which is simply because at low speeds they turn into Newton's, and the effective MEANS of gravity doesn't matter, just the way it acts).

[Raapys]

I see his point, though. Much of what we "know to be true" is just based on vague and unproven theories, and these hole-riddled theories are the base for which new scientific work is done.

Sort of like putting all your already-broken eggs in a basket that's also about to break.

I'm really curious as to how he goes about explaining the universe, though. Have anyone read the full book?

[Phoenix-D]

Example 3 from the skim, and this one is REALLY amusing:

d = ½at2. Constant acceleration equation. He claims this doesn't have any relationship to gravity at all. No physical forces at all. Except, oh, a. Which is...drumroll please...acceleration due to gravity.

I can guess what his theory would be from all this: crap, and more crap. Scientific theories are used to describe the world, and they do have problems, but they aren't anywhere near as problematic as you're implying, Raapys.

[Raapys]

Well, my knowledge in the area of science isn't exactly staggering, so I wont try to defend my perhaps rash statement.

However, isn't it true much of what he says? One example; how can the law of conservation of energy( "Energy can not be created nor destroyed, only changed from one form to another" ) and the laws of gravitation exist both at the same time; aren't they massive contradictions?

[AngleWyrm]

The whole book is on P2P for download (magnet:?xt=urn:ed2khash:dfdb8e25e34d3f8186fca2296 43cec69&dn=McCutcheon_Mark_The_Final_Theory_of_Eve rything.pdf&xl=16849054) as a pdf.

While he does raise important questions in the first chapter, his answers are defended with "thought experiments"--a concept attributed to Einstein--which is in my opinion poor science.

"If the earth were to suddenly disappear..." does not have anything to do with the universe in which we live. And understanding the universe in which we live is a big part of it.

[GuyOfDoom]

Thought Experiments are nice examples to show people and serve as the framework for actual experiments, which the man seems to be greatly lacking.

[Raapys]

I found an interesting review of the book over here.

http://www.dpedtech.com/FTreview.pdf

[GuyOfDoom]

Wow. With a review like that you might as well call it a counter-novel.

[Raapys]

Yeah, I'm not sure what to make of this stuff. He goes on about his own theories and thoughts more than the actual stuff in the book he's reviewing. And he really likes metaphores.


Pick a desire, especially a nice little addiction. Say you like chocolate. Notice how
you feel about chocolate. Do you have a certain amount of attention fixated on
chocolate? Go find some chocolate. Feel how it is when you approach the chocolate.
Put some in your mouth and enjoy the momentary pleasure of tasting and chewing and
swallowing it. That is how gravity works.

[Renegade 13]

GuyOfDoom said:

capnq said:
There's a "popular science" book called The Trouble with Physics (http://www.thetroublewithphysics.com/) which argues that string theory is a seriously flawed dead end that's sucking attention away from more promising alternatives.



I've gotten the impression from some of your posts that you don't seem to be a big fan of science in general.

Personally, I'd call Capnq a skeptic, which is a good thing in today's world. http://forum.shrapnelgames.com/images/smilies/tongue.gif

[GuyOfDoom]

Renegade 13 said:
Personally, I'd call Capnq a skeptic, which is a good thing in today's world. http://forum.shrapnelgames.com/images/smilies/tongue.gif



It depends on the focus and the intensity of the skepticism. As always too much or too little is a bad thing.

[Phoenix-D]

Raapys said:
However, isn't it true much of what he says? One example; how can the law of conservation of energy( "Energy can not be created nor destroyed, only changed from one form to another" ) and the laws of gravitation exist both at the same time; aren't they massive contradictions?



Not really. And even if they were, the way he uses them is incorrect; if a law contradicts another law, they have more or less equal chance to be wrong.

Gravity seems to be an intrinsic property of mass. If that's the case it wouldn't use energy the same way as being blue doesn't use energy. (think of reflections the same way. A photon hits an object, then bounces off..at the same wavelength! It changed direction, so obviously there was some energy used to change its course, right? Answer:..not really)

EDIT: I should point out that my specialty is biology, not physics. However I have seen this sort of claim with biology as well (hi there, creationists), and the logic matches. Plus the way he advertise his book- "the book our scientists hope you never read". Usually the kind of thing kooks use.

[Raapys]

I don't know, I still don't see how gravity and magnetism are *not* infinite sources of energy. They can both definitely apply kinetic energy to other masses, and to our knowledge they do not weaken over time, indicating they are inexhaustible.

Photons are a special case, aren't they? Since they can, apparantly, be slowed down by passing through certain matter, then speed up again entirely by themselves.

[se5a]

because you have to spend the same amount or more energy getting an object back up the hill as you got from it rolling down the hill.

[Phoenix-D]

Gravity first: the best explanation at the moment is Einstein's. Gravity is -not- considered a force there, and doesn't 'use' any energy. Rather its something mass does to spacetime, with the side effect of making masses move toward each other.

Even that theory isn't complete yet, though, as it doesn't work on the level of atoms (possibly because gravity is so weak at that scale).

Magnetics: same general idea. Its caused by the movement of charged particles though, and to explain those you get into QM, which is mind-bendingly freaky.

Something to remember: Newton's theories are *wrong*. Darwin's theory was *wrong*. In both cases however, they still serve as a strong base for use and further experiment; the areas where they are wrong are small enough they don't impact day-to-day work.

[Raapys]

because you have to spend the same amount or more energy getting an object back up the hill as you got from it rolling down the hill.



But that's not actually true. If you pick up a box and hold it for one hour then you've spent alot more energy than if you merly lift it up and drop it at once. Yet, the box doesn't have any more energy when it falls after one hour than it does if you release it instantly. So where did the energy you continously applied to the box for one hour go?

PhoenixD: Alright, I can go with the spacetime theory as passable, but that still doesn't account for the fact that gravity does 'consume' the kinetic energy of masses, which means we still have a change in the amount of energy in the universe. Or am I missing something? Where's the kinetic energy going?

It does all sound a little odd, since if energy = mass, and mass is what creates gravity, and gravity drains energy, then we're left with mass that is actually consuming itself.

Oh, and while we're on the mystic and unexplained, does anyone know why *REPLICA WATCHES* are so popular? My inbox has been continously spammed with that stuff for over a year.

[GuyOfDoom]

Darwin's theory was *wrong*



Admittedly I've never read Origin of Species, but I don't believe he states where life started, which is a large misconception. As for his theory being wrong, I'm confused as Evolution happens, but not precisely in the way he was able to observe at the time.

[narf poit chez BOOM]

I could explain how standing on a surface does not use energy save in inneficiency, but Fyron was the one who explained it to me and as it's been about a year, I'm not sure I can explain it.

[Spoo]

Raapys said:
If you pick up a box and hold it for one hour then you've spent alot more energy than if you merly lift it up and drop it at once. Yet, the box doesn't have any more energy when it falls after one hour than it does if you release it instantly. So where did the energy you continously applied to the box for one hour go?



Your muscles require a constant use of energy to remain contracted. That energy ultimately "goes" into heating your body over the course of the hour that you spent holding the box.

[Raapys]

But you're keeping your muscles contracted *to keep the thing from falling to the ground*, thus you are, for that entire hour, applying more and more kinetic energy to the box. Put it like this: if the gravity was to suddenly vanish, the box would go flying off from the force you were exerting on it at that given moment. You're not exerting any less force on it just because it's not moving.

[Suicide Junkie]

It would drift off very slowly.

It starts at rest relative to you and the surface of the Earth, and you will be pushing 9.8m/s^2 for maybe 1/10th of a second before you notice and stop pushing.

You aren't actually adding any kinetic energy to the box.
Work = force * distance.

Effort feels more like force * time, but it dosen't have any serious meaning.

[Raapys]

But the 'work = force * distance' function is fatally flawed when used in this situation, because the result of the equation will be zero, indicating no energy has been spent, no work has been done. Obviously this is completely incorrect, since you'll be standing there sweaty and tired, having wasted alot of energy on the task.

I think a fitting metaphor would be two guys pulling each side of a rope. They're both applying kinetic energy to the rope, but in different directions, canceling it out. So even if the rope isn't actually moving, there's still alot of work being done on it. The difference is that where both these two guys would eventually get tired, gravity does not.

Hmm, I guess one solution would be that the force you're using to hold the box up is simply being applied as kinetic energy to the *Earth*, thus seemingly 'disappearing' since it's hardly noticeable for something on that scale.

[se5a]

they're not applying kinetic engergy, it would be... burning organic matter and turning it into heat mostly.
I think...

[Spoo]

Raapys said:
But the 'work = force * distance' function is fatally flawed when used in this situation, because the result of the equation will be zero, indicating no energy has been spent, no work has been done. Obviously this is completely incorrect, since you'll be standing there sweaty and tired, having wasted alot of energy on the task.



Work is being done in the sense that ions are being moved around in your muscle cells to keep the muscle contracted.


I think a fitting metaphor would be two guys pulling each side of a rope. They're both applying kinetic energy to the rope, but in different directions, canceling it out. So even if the rope isn't actually moving, there's still alot of work being done on it. The difference is that where both these two guys would eventually get tired, gravity does not.



The rope isn't moving, thus it has no kinetic energy. Likewise, no work is done on the rope (although the two guys will grow tired because work is being done within their muscle cells).

[Raapys]

Work is being done in the sense that ions are being moved around in your muscle cells to keep the muscle contracted.



Yes, to the same degree that it's being done when you're actually moving something. But where does the energy that you use to move something go when you're not strong enough to move it? Or when you're using the same power that you used to move something to just fight gravity?


The rope isn't moving, thus it has no kinetic energy. Likewise, no work is done on the rope (although the two guys will grow tired because work is being done within their muscle cells).



The rope isn't moving, true, and thus it has no kinetic energy. However, it *is* being applied kinetic energy; it's just that it's being applied the same amount of energy pulled in opposite directions, thus canceling out. *Obviously* work is being done on the rope, because if they both pull hard enough, after all, they could rip it in two. Yet using the, in this case faulty, work = force * distance equation, you'll still get 'zero work has been done' even if you have ripped it in two and applied massive forces on the rope to do it. The equation is useless for these sorts of scenarios, since it requires that a distance has been covered to get a non-zero result.

Let's say we invented kinetic energy weapons. They shoot a small amount of pure kinetic energy. We're in space, and there's a metal cube or whatever floating directly between two ships which have these weapons mounted. They're at the same distance from the cube, etc. Then, at the exact same moment, both of them fire their weapon at this object. The weapon applies the energy to the entire cube at the same instant.

What happens?

[Phoenix-D]

GuyOfDoom said:

Darwin's theory was *wrong*



Admittedly I've never read Origin of Species, but I don't believe he states where life started, which is a large misconception. As for his theory being wrong, I'm confused as Evolution happens, but not precisely in the way he was able to observe at the time.



No, I don't think he did. However the view of evolution posited in that book has gone through so many revisions I feel quite comfortable in saying he was wrong. http://forum.shrapnelgames.com/images/smilies/happy.gif

[Suicide Junkie]

The ripping process eats up a lot of energy in the breaking of bonds and a bit in the final acceleration of the two halves of the rope.

In the ship example, presuming the block and shots all stick together, you end up with a block with two bullets in it, and two ships both moving away from the block.

The thing you're not getting is that you don't "apply kinetic energy" to anything. You exert forces. The force may be countered by friction or an opposing force.
You can waste energy all you want, you'll just get hot and sweaty without getting the result you wanted.

[se5a]

we don't need to "invent" a kenetic energy weapon, we've already got them, that is precicely what a rifle is.
an object has kenetic energy when it is moving.
when it is at rest, it has no kenetic energy.

[GuyOfDoom]

Phoenix-D said:

GuyOfDoom said:

Darwin's theory was *wrong*



Admittedly I've never read Origin of Species, but I don't believe he states where life started, which is a large misconception. As for his theory being wrong, I'm confused as Evolution happens, but not precisely in the way he was able to observe at the time.



No, I don't think he did. However the view of evolution posited in that book has gone through so many revisions I feel quite comfortable in saying he was wrong. http://forum.shrapnelgames.com/images/smilies/happy.gif



True enough. Darwin is too often credited with the "origin theory" of evolution when it really doesn't have anything to do with the origin of life.

[Raapys]

The ripping process eats up a lot of energy in the breaking of bonds and a bit in the final acceleration of the two halves of the rope.



In other words, work is being done on the rope, even though the work formula wont agree. The kinetic energy being applied by the two guys pulling the rope are ripping apart the bonds holding it together. Right?


The thing you're not getting is that you don't "apply kinetic energy" to anything. You exert forces. The force may be countered by friction or an opposing force.



But that was my point; if you're fighting gravity, or magnetism, then isn't energy "disappearing", since gravity and magnetism doesn't weaken( i.e. they have infinite power )?

And also, why wouldn't 'exerting forces' be exactly the same as applying kinetic energy? It's no less 'applying k. energy' just because it's not moving; that just means another force is applying a bigger amount of kinetic energy than you are, and in a different direction. Or in the case of an atmosphere, where you're not just pushing the object, but the air particles covering the direction you're pushing it in as well.

[capnq]

GuyOfDoom said: I've gotten the impression from some of your posts that you don't seem to be a big fan of science in general.

No, I'm quite pro-science. What I'm against is the cynical exploitation of public ignorance of science to further personal and political agendas.

I haven't read the book I linked to, but I did read about half of the reviews linked from that site. The author's argument is more with the attitudes of the scientific community than it is with the theory itself.

[AgentZero]

Raapys said:
And also, why wouldn't 'exerting forces' be exactly the same as applying kinetic energy? It's no less 'applying k. energy' just because it's not moving; that just means another force is applying a bigger amount of kinetic energy than you are, and in a different direction. Or in the case of an atmosphere, where you're not just pushing the object, but the air particles covering the direction you're pushing it in as well.



Kinetic energy is loosely defined as "extra energy an object has due to motion." You cannot apply kinetic energy to anything. You just can't. What you can do is apply force to an object, and if the force you apply to the object makes it move, then it gains kinetic energy, but you didn't give the object the kinetic energy. You gave the object force, which resulted in motion, and by virtue of said motion, it gained kinetic energy.

As for objects not moving, keep in mind that the law of conservation of energy states that you cannot create or destroy energy, only convert it between forms. So, you go and push on a big rock. You're using chemical energy derived from food to apply force to the rock. But say it's a big rock, and it won't move. The chemical energy you use to create the force is thus converted into heat in your body. Have you ever noticed you get hot & sweaty faster when you try to move something that's too heavy to move, compared to something that's just heavy enough that you can move it? I'll probably get whacked by the sciency folks for that comparisson, but my grade 11 physics teacher used it to illustrate the point, so I'm using it too. http://forum.shrapnelgames.com/images/smilies/tongue.gif

I hope that made sense.

[Renegade 13]

And the force you are applying to the aforementioned large rock isn't disappearing either; it's being "eaten up" by friction between the rock and the Earth, etc. You could apply a lot of force to the rock, but if you can't overcome the coefficient of friction, all you're doing is ultimately applying all the energy you exerted on the rock into the Earth, which is holding the rock still.

[Raapys]

Yeah, but then 'what is force'? Isn't exerting force actually just transference of kinetic energy? If an object floats, completely still, in space, and another object bumps into it, isn't it true that the previously still object will start to move and the previously moving object will stop( assuming a perfect collision between like masses )?

Renegade, friction wont matter if you're lifting it straight upwards, though.

Anyway, I'll try not to drag this around in circles forever. I was just thinking that surely gravity would be both a creator and a destructor of energy.

Given a rope, a tree, a bucket of water, a gravity switch and Earth: The tree is on earth, the rope is hanging from the tree, the bucket of water is hanging from the rope and is so heavy that it'll snap the rope within one minute. The gravity switch is off.

You turn on the switch. What happens? Gravity starts pulling, exerting force as you would say, on everything. With the help of the bucket of water, gravity is actually pulling with enough energy to break the bonds in the rope.

The big question: Where's gravity getting its energy from? And even if gravity itself doesn't actually need any energy to work( i.e. spacetime ), gravity *is* exerting force on the bucket making it move. When it's moving it has kinetic energy. Since gravity made it move, that means gravity *created* energy, no?. To our knowledge, gravity doesn't weaken over time( unless given external events ). Gravity could be doing this with billions and billions of buckets all over the world, forever really. So what am I missing? How is this not an infinite energy scenario and something that breaks the law of conservation of energy?

Sorry if I'm being difficult. I understand what you guys are saying; it's along the lines of what I did learn when I actually went to school. I just can't get it all to add up.

And how is it that a photon can slow down when passing through other mass, then speed up again on its own accord? Doesn't that too go against a number of laws?

[Suicide Junkie]

You don't have to expend energy to apply a force. The spring in your ballpoint pen (the clicky kind) is always exerting force on the clicker, but that dosen't in itself mean that the pen is mightier than the sword.

Change in energy = Work = Force (dot) Distance
(Dot product of the vectors) this is the same as simple multiplication if the force and movement are in the same direction. (Negative if they're in opposite directions, and zero if they are perpendicular)

No movement means no transfer of kinetic energy regardless of the force applied.

[AngleWyrm]

Something's amiss with the Work formula. If I lift a brick straight up it takes some effort. If I lower that brick straight down, it doesn't feel like I've exerted as much effert. If I push it sideways on a slippery surface, it takes almost no effort at all.

If I carry a rock to the top of a mountain, did I store energy in some sort of battery? Potential Energy? I notice that pendulums and bouncy balls and roller coasters have enough energy in their battery to bounce all the way back up to very nearly where they were. Odd that we say it was Momentum carried it back up to where it was. If I put enough energy in a brick to lift it six feet from the sand, we have no problem saying that was just enough energy to go back down. But it looks like twice as much on the way down, doesn't it?

What if I tossed a steel marble up in a vacuum sealed metal box here on earth? Would it continue to bounce up to some specific height? And doesn't that look a lot like orbiting, viewed from an angle?

[AgentZero]

Something's amiss with the Work formula. If I lift a brick straight up it takes some effort. If I lower that brick straight down, it doesn't feel like I've exerted as much effert. If I push it sideways on a slippery surface, it takes almost no effort at all.



I only got a C in highschool physics, so I'm no expert, but the way I remember it working is this: When you lift the brick, you're working against gravity, so you personally do most of the work, so it seems hard. When you lower the brick, gravity is doing most of the work, so to you it seems easy. But either way, the same amount of work is being exerted on the brick. I think the work formula by itself is based on moving things through the air, and you have to make additional calculations for friction when you're moving an object across a surface. Or something. I was sick when we covered friction so I'm kinda fuzzy on it.


What if I tossed a steel marble up in a vacuum sealed metal box here on earth? Would it continue to bounce up to some specific height?



Things stop bouncing because every time they hit the object they're bouncing against, they transfer some of their energy into what ever they're bouncing against, so your marble would probably bounce just the same in a vacuum as it does in the atmosphere, since air friction plays a very small part in slowing the marble. Otherwise, air being thin as it is, things would bounce for a very long time!

[Raapys]

Change in energy = Work = Force (dot) Distance


But the work formula doesn't cut it. It doesn't even take into account that the force being applied could have ripped apart atomic bindings and the likes( which means that *some work* has definitely been done, regardless of what the formula says ) even if the object wasn't actually moved.


No movement means no transfer of kinetic energy regardless of the force applied.


Gravity does generate movement, and accelerates/decelerates other objects, without tiring.

But what's the difference between saying what you're saying, and saying that kinetic energy is always being transfered, it's just going elsewhere? If you're far away in space and you push something, then accoding to the work formula, work is *always* being done, because away from gravity even the smallest amount of force exerted on an object will get it to move. Agreed?

Let's not forget that kinetic energy is really *all energy*. Even the heat and sweat of your body when doing work is at base kinetic energy. For that matter, heat *is* kinetic energy; the hotter it is, the faster the particles move, the more kinetic energy they have. The work formula only takes into account work done on a visible level, it doesn't take into account work done on an atomic, or even smaller, level.

[Suicide Junkie]

It does not take any energy to apply a force.
It does take energy to accelerate an object.

You gain energy if you fall in a gravitational field (since you are moving with the force.
You lose energy if you move against the force (upwards).

If you do the integral, you will find that the escape velocity of Earth is 11.186 km/s (The kinetic energy is scaled by mass and the force of gravity is scaled by mass too, so mass cancels out)
If you are moving outwards, you lose kinetic energy and speed, but gain potential energy for being higher up and having farther to fall.
Kinetic energy is NOT all energy.

A compressed spring isn't hotter or moving any faster than a relaxed one. And that the stretched slingshot dosen't move either... and how about all that chemical potential energy in your car's fuel tank?

[Raapys]

Kinetic energy is NOT all energy.
A compressed spring isn't hotter or moving any faster than a relaxed one. And that the stretched slingshot dosen't move either... and how about all that chemical potential energy in your car's fuel tank?


You're right, I wasn't thinking.


If you are moving outwards, you lose kinetic energy and speed, but gain potential energy for being higher up and having farther to fall.


I see what you're saying, but I mean, the 'potential energy' you are talking about is a product of gravity. What when an object's speed does exceed the escape velocity; where does the kinetic energy the object loses on the way out, because of gravity, go? Since the object will never be stopped by that mass's gravity once it's reached e.v. that means no potential energy was created but alot of existing energy was lost, or?

[Suicide Junkie]

Its gravitational potential energy. If the object falls down into any gravitational well, that turns back into kinertic energy.

What goes up does *not* have to come back down. That's the point of escape velocity.

You recall those distorted funnel grid paper things that are always used on tv to show gravity fields?
The height represents the potential energy. If the object moves into the depressions, its potential energy is decreasing. In a vaccuum, that pretty much all turns into kinetic energy and back when the object orbits around.

[Fyron]

Raapys said:
But the work formula doesn't cut it. It doesn't even take into account that the force being applied could have ripped apart atomic bindings and the likes even if the object wasn't actually moved.

Perhaps because you can't "rip apart atomic bindings" by pulling on a rope? No amount of force you can apply will overcome the strong nuclear force... Though if you are talking about inter-molecular bonds, those can certainly be broken in the process of applying (thermodynamic) work. But you seem to be thinking of mechanical work...

When you are talking about work, it makes a huge difference which type of work you are talking about. "Work" is a horribly generic word that can mean many different things.

If an object does not move, no mechanical work was done. Mechanical work is purely a derived property of force applied and distance moved. W = F * D is entirely correct, in the mechanical sense of work. Mechanical work does not take heat or other forms of energy transference into account; it only deals with force applied and distance moved.

In the thermodynamic sense of work, you can do work without moving an object. Thermodynamic work is a generalization of the mechanical concept of work; it is a quantity of energy transfered from one system to another. It includes the microscopic thermal motion of particles (aka heat), as well as macroscopic changes to the system (movement, fluid expansion, chemically charging a battery, etc.).

Lets say you decide to push on a wall, which is sturdy enough to resist all of your efforts. Was work performed? No, and yes.

In the mechanical sense, no work was done. The wall was not moved, regardless of how much force you applied. F * 0 is 0.

In the thermodynamic sense, yes, work was done. Your muscles contracted, which required burning up stored carbohydrates and such. This generated heat, which dissipated into your body, the surrounding environment, and perhaps a bit into the wall itself. The force applied on the wall by your hands pushed the wall's molecules ever so slightly inward; this is essentially imparting some kinetic energy from your hands' molecules to the wall's molecules, which in turn is rapidly converted into potential energy. The resulting electromagnetic forces pushed back, resisting any overall change to the structure or location of the wall. In the end, there winds up being no kinetic energy in the wall (when looking holistically at the wall itself). Friction at work (yet another meaning of work... bloody English http://forum.shrapnelgames.com/images/smilies/wink.gif). Hopefully I didn't miss anything there, but you get the idea.

The same exact analysis applies to two people pulling on a rope (without breaking it), save that now you have heat dissipation from 2 people and tension at play. You have lots of thermodynamic work going on, but no mechanical work at all (at least, until the rope breaks).

[AgentZero]

Four pages of debate on the principles of physics before Fyron shows up. I was starting to get worried there. http://forum.shrapnelgames.com/images/smilies/wink.gif But now everything makes a lot more sense and I think I might have learned something too, so the wait was worth it.

Now on to more important matters. Why does my beard smell funny after I wash it? It has the same smell regardless of what I wash it with. http://forum.shrapnelgames.com/images/smilies/tongue.gif

[Raapys]

Its gravitational potential energy. If the object falls down into any gravitational well, that turns back into kinertic energy.


So what's really being said is that graivty doesn't create or destroy energy, because it was always 'potentially' there? I.e., potential energy is being treated as existing energy.

Thanks alot for the detailed work explanation Fyron.

[Renegade 13]

AgentZero said:
Now on to more important matters. Why does my beard smell funny after I wash it? It has the same smell regardless of what I wash it with. http://forum.shrapnelgames.com/images/smilies/tongue.gif

You must not be getting all the accumulated food particles out of it! http://forum.shrapnelgames.com/images/smilies/tongue.gif

[AngleWyrm]

AgentZero said:
Now on to more important matters. Why does my beard smell funny after I wash it? It has the same smell regardless of what I wash it with. http://forum.shrapnelgames.com/images/smilies/tongue.gif


The Work performed in washing it was stored as potential energy in the gravitational field. So when it came out as kinetic energy, it had picked up some field odors.

[AgentZero]

AngleWyrm said:
The Work performed in washing it was stored as potential energy in the gravitational field. So when it came out as kinetic energy, it had picked up some field odors.



Field odours! Magnificent! Now all we need is some sort of field odour nulification device to prevent post-shower smelliness. I'd pay a pretty penny for such a device, and I'm sure my brothers in fur would too.

[AngleWyrm]

Oh I like pretty pennies! New technological marvel:
The Covariantly Layered Orthagonally Teathered Hyper Energized Stored Potential Induced Nullifier

http://www.duanekeiser.com/Assets/clothespin2.jpg

[Suicide Junkie]

It sounds like implying some wierd things there Raapys.

You do recognize that a spring and a bullet have a fixed amount of potential energy (which are commonly converted into kinetic energy and boing noises, and light, heat and kinetic energy respectively)
Same deal with separated objects in a gravitational field.
Same deal with magnets and electric charges.

[Raapys]

Hmm, I definitely see your point in the spring and bullet scenarios, where it's obvious that there is energy waiting to be released, but with gravity too?

To clarify my question: If we had a device that could read the potential energy we're talking about, then that device would generally, in the case of a compressed spring, come up with the amount of energy used to compress it, right?
But would you also be able to "find" the ( potential ) gravity energy?

I guess my point is, isn't the potential energy of the spring real, i.e. it's actually in the atoms and can be measured, while the potential gravity energy isn't ?

[Suicide Junkie]

Why would you think gravitational potential energy is not real?
You drop a bowling ball, and it crushes your toe. That's definitely real energy.

On the small scale, it simplifies to mgh. For larger scales you need integrals. But it is all very straightforward.

The only difference is scale. In the spring, you have electric forces pushing or pulling (but you have to look on the molecular scale). Gravity works on scales big enough to see and just pulls.

BTW, since gravity is always attractive, the arbitrary zero point is generally placed at infinity. So if you fall inwards, your gravitational potential becomes negative.
Conveniently, setting the point there means that if your total energy is positive, you can escape. If the total is negative, you're stuck in the gravity well unless you steal some energy from something else.

[GuyOfDoom]

I think what is trying to be said is that if we understood enough about gravity we could potential control it and generate a "limitless" supply of PE since gravity only weakens over distance and not time.

[Suicide Junkie]

*Sigh*

[GuyOfDoom]

I realize the point you're trying to get across, but the end all be all is the fact that the mechanism behind gravity is still a mystery. The definitions of energy are left intentionally vague because we don't understand them completely.

Gravity is a property of matter, but how is it "enforced." That's where gravitons come in.

[Suicide Junkie]

ALL the fundamental forces do not fade with time. Gravity is nothing special.

The only reason why everyday forces fade is because they do work on stuff and thus dissipate the energy into the environment.
If you don't let your Bowling ball fall, it dosen't lose any potential energy. If you don't let your spring expand (or rust out!) then it dosen't lose any energy. If you don't let your flywheel interact with the environment, it won't slow down, but it will still be exerting a lot of force to keep the outer edge of it moving in a circle.

Conversely, if you use a realistic flywheel, the bearings will introduce friction and sap your kinetic energy into heat and noise.
If you use a realistic spring, it suffers chemical reactions, and metal fatigue.
If you have your bowling ball sitting outside, it will sink into the mud.

[Raapys]

I'm just not sure what the difference would be between saying that "This object has potential gravitational energy that is being transformed to kinetic energy as it approaches another mass" and saying that "Gravity creates kinetic energy in this object as it approaches a mass, or destroys it as it moves away from a mass".

The first one corresponds with the energy conservation law, the second one does not. Can it actually be proven that the first one is more true than the second?

The reason I mentioned potential gravitational energy not being real is because it can't be put on a weight. I mean, you can weigh 'normal' energy, since it actually has mass, but gravitational potential energy doesn't, to my knowledge.

[Fyron]

There is a huge body of empirical evidence supporting the veracity of the conservation of energy law.

[AgentZero]

Veracity is one of my favourite words.

[capnq]

Suicide Junkie said: ALL the fundamental forces do not fade with time. Gravity is nothing special.

"Constants aren't. Variables don't."

Paul Dirac (http://en.wikipedia.org/wiki/Paul_Dirac) speculated about the gravitational "constant" varying over time all the way back in 1938. This article (http://www.rssd.esa.int/SA-general/Projects/GAIA_files/LATEX2HTML/node143.html) lists the current upper bound for how fast it could be changing. Some versions of string theory allow for the possibility that other "constants" also change over time.

[Suicide Junkie]

That's not what we were talking about.

Gravity and electromagnetism don't run down like a battery.