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Here's a thought for people to kick around (out?).
The Universe contains only two kinds of energy: Kinetic energy and potential energy.
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My kick around .... I toy with this stuff all the time
Potential energy against what? Chemical potential Gravitational potential Electrical Potential Nuclear potential
Why does E=MC2 what has light got to do with things and does it have potential energy or kinetic energy?
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
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Potential energy against what? Is potential energy any less "potential energy" because it can be classified as one variety or another? Is it not all potential energy?
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My take on the difference between kinetic energy and potential energy? Forget it. Energy is all there is. It has several forms and most of the forms are dependent on what your point of view is. There is radiant energy, which is primarily electromagnetic energy. There is matter, which is just energy wrapped up in a small volume. There is mechanical energy, there is electrical energy.
Kinetic energy and potential energy are basically just book keeping. They are ways of stating how much energy you can get out of a system. And they are relative. For example if you are sitting in a stationary car and there is a road under the car that is moving at 70 mph with respect to the car, then the car will have 0 kinetic energy and 0 potential energy. However, a concrete barrier on the road that is approaching at 70 mph will have a large kinetic energy.
And if you think my road is ridiculous, think about running on a treadmill, it is about the same thing.
Bill Gill
C is not the speed of light in a vacuum. C is the universal speed limit.
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then the car will have 0 kinetic energy and 0 potential energy. Let's look a little closer at the idea of 0 potential energy. Suppose your mobile road had a hole in it, say 100m deep, as it aligned itself with the car, the car would suddenly acquire considerable potential energy, without having done anything.
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OK, that is a red herring. A few questions arise from your last post, Bill, the first of which is: how do you define radiant energy, and electromagnetic energy. I suppose that's two questions really.
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I don't think I have much to add to what I said. As I said radiant energy is primarily electromagnetic energy, which is the energy carried by an electromagnetic wave. But basically energy is energy. Everything else is book keeping, and I think that is enough said.
Bill Gill
C is not the speed of light in a vacuum. C is the universal speed limit.
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A hole?
Whats holding the stuff together to put a hole in ... IE whats binding your road together?
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
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Orac, I'm not sure that I see the problem. We are all familiar with holes in the road. If we can imagine a stationary car on a road that is moving at 70mph, how difficult is it to imagine a hole moving with the road?
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BTW, Bill, I don't think your road is ridiculous, I think Einstein's "Does Oxford stop at this train?" might be apocryphal, but the idea is the same.
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Orac, I'm not letting the dreaded thread drift deprive me of an answer to my earlier question.
"Is potential energy any less "potential energy" because it can be classified as one variety or another? Is it not all potential energy?"
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Well, I was going to try to drop out of this thread, but I will go ahead and try one more time.
Potential energy is the energy you can get out of a system when it transforms from one state to another. It depends on the difference in energy levels between the 2 states. As such it is purely relative to the system in which it is being calculated. Oh, it does have to be calculated, I don't think you can measure potential energy. It is a valuable concept in some areas, such as engineering a hydroelectric station. But in itself it is just another useful concept for making calculations. It does not exist as an independent entity. As I have said before it is just a form of book keeping.
Bill Gill
C is not the speed of light in a vacuum. C is the universal speed limit.
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What Bill is describing is technically called gauge theory ( http://en.wikipedia.org/wiki/Introduction_to_gauge_theory) I guess my view is if you have two states like Bill has given you why does it want to move down to the lower level, that is why when I release the ball does it drop rather than float up under gravity. What causes the directionality? The normal view science view is that you are implying a stored force or a static force if you like a rubber band. And there in lies the basic problem the moment you introduce a force there has to be something opposing it or else it will collapse or move (Newton called it the 3rd law). And that leads you straight into the 4 fundemental forces if you believe the story :-) ( http://en.wikipedia.org/wiki/Fundamental_interaction) Why I say believe the story because there is no actual proof of the 3rd law its totally deduced and worse we have no explaination of directionality it's the same as times arrow. Nothing in gauge theory implies direction there would be no reason the ball shouldn't fall upwards because like most things in physics it can go both ways. Infact in some universe the laws of physics could be upside down and balls would fall up and all our formula's would work but backwards. For some reason gravity has a direction as does energy as does time in our universe. Explain those expalin the universe.
Last edited by Orac; 08/04/11 07:11 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
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Can't you side-step at least some of those directionality issues, Orac, by explaining them in terms of General Relativity?
"Time is what prevents everything from happening at once" - John Wheeler
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As I approach my first anniversary as a SAGG poster I asked myself a few questions about the experience.
1. Are you likely to get a straight answer to a question? Unlikely.
2. Will you get a lively discussion with lots of food for thought? Usually.
3. Will it be fun? You bet it will.
As far as this topic is concerned, I'm not sure that I am any further forward than I was at the start. Maybe there's more to come.
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A really naive thought!!! Quote from: http://motls.blogspot.com/2006/07/columbia-university-crackpot-joins.html"Where is the energy that keeps the moon in orbit coming from? Well the moon already has some energy so lets look at that first. Its moving, so it has kinetic energy (the energy of motion) and it is in a gravitational field so it has potential energy. While the moon circles the Earth it actually trades gravitational potential energy and kinetic energy. As it moves away from the earth it gains potential, as it does this it slows down losing potential. This causes it to move back towards the earth, losing potential and gain kinetic. It doesn't have enough energy to escape earth’s pull, which would require more kinetic energy than it has to over come the potential energy of the gravitational field." Has the moon, and every other orbiting body, discovered perpetual motion?
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Can't you side-step at least some of those directionality issues, Orac, by explaining them in terms of General Relativity? No it gets worse under GR because gravity is basically seen as things running down the gradient ... 1 sec let me see if I can find a visualization I like ... there ... ( http://web.mac.com/limuti/DWT/23_Gravity_Visualized.html) or another way ( http://www.adamtoons.de/physics/gravitation.swf) So basically its like a soft foam matress put two heavy balls on it they displace the foam and want to run together ... married couples in bed should be very used to te effect :-) So now you are left with the sticky problem where Bill ends up what the hell is stopping it all just collapsing. Why don't all the planets just collapse into one big ball. You can show the effect even in newtonian simulator just use a one sided gravity equation. ( http://www.myphysicslab.com/beta/Inverse-square-gravity.html) Take the elasticity to zero so they don't bounce and see what happens. So this is very much Bills problem as I see it potential energy at its most basic in gravity under our physics laws wants to drag stuff together .... what stops it? See at it's heart the really big problem is a really simple question and I guess what I am saying is Bill is simply reworking the known bit but he still does not touch on answering the opposing ... that is all that potential energy is massive ... why doesnt it just collapse the universe in a blinding flash.
Last edited by Orac; 08/05/11 03:51 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
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So this is very much Bills problem as I see it potential energy at its most basic in gravity under our physics laws wants to drag stuff together .... what stops it? Not absolutely sure which Bill you mean. If you mean me, that's not really my problem; not that I restrict myself to only one! My main problem is contained in my last post. How does the moon keep orbiting the Earth, exchanging potential and kinetic energy, apparently withour loss or input of energy? A few people have already tried to explain this to me, but either I have a bad blind spot, or there is something still unsaid.
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Thats because you have to start with forces not energy ... this sort of leads back to the above problem. For energy to be measured you first have to produce a force against something and that takes us to the four fundemental forces ( http://library.thinkquest.org/27930/forces.htm) So for your orbital problem we have two forces Gravity trying to pull the objects together (A fundemental force) Centrifugal force trying to throw the objects apart (A fictional force born of motion) Viewed like that at any point in the orbit those two forces are balanced. The energy flow is a side product of the forces. This will help you can view the energy and forces etc (http://www.phys.hawaii.edu/~teb/java/ntnujava/Kepler/Kepler.html). If you turn it into energy display it will show you the flow the calc is down below. This is sort of what I was saying at the start you can't really start with energy because there is no directionality in energy you can't balance things into cycles. Forces are directional they are always the start point we tend to think energy is but that is wrong. Every motor, every system we make we impart directionality to make them start .... a car engine can go backwards if not timed properly and the starter motor starts it rolling forward. I know of not to many things that will start without at least a gentle nudge to impart the direction we want it to go. And that leads us back to the start ... in the universe what is the force pushing against and why the directionality.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
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Forces are directional they are always the start point we tend to think energy is but that is wrong. Every motor, every system we make we impart directionality to make them start .... a car engine can go backwards if not timed properly and the starter motor starts it rolling forward. I know of not to many things that will start without at least a gentle nudge to impart the direction we want it to go.
And that leads us back to the start ... in the universe what is the force pushing against and why the directionality. Well, in the beginning things were moving in random directions. So some of them would randomly start moving in the same direction. As gravity pulled things together things would randomly start moving toward the center of gravity in a chaotic manner. When more of them started moving off to one side of of the center of gravity they would acquire angular momentum that would keep them moving in a generally circular path around the center of gravity. Since angular momentum is conserved that circular path would be kept up and things would be spinning. I assume that the the universe has a net angular momentum of zero, but I don't really know that. Anyway once a particular subsystem started spinning then it would keep up that spin, so there was no force that directed the motion of objects in orbit around other objects (such as the Moon around the Earth), it was just a random collection of angular momenta. Anyway that's how I see it. Bill Gill
C is not the speed of light in a vacuum. C is the universal speed limit.
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