The destruction of energy

1. Aug 18, 2013

Atwun

It has been said that energy cannot be created or destroyed. If energy is matter in motion, and if matter stops moving, than why can it not be said that; where there was energy, there is no more? After being in motion could matter only stop moving and therefore cease to be considered energy, if matter elsewhere increased in terms of velocity?

As I read over this which I have wrote, I realize that it most likely should not have been posted under the general and special theory of relativity section. This possible mistake was made by me because my post does deal with the concept of relativity. If you've been in a stationary vehicle which has next to it a vehicle that is moving ahead, then you've might have had the thought that you were moving going in reverse.

Imagine a highway where there is bumper to bumper traffic. A new car moving quickly enters onto the highway. That new car can come to a complete stop if it crashes into the line of cars that are hardly moving. My question above is then illustrated by the fact that the other cars on the road must increase in velocity for the car entering onto the highway to come to a halt and when it does...when that car, when the object, the segment of matter, is no longer moving, then why could this not be called the end of motion and therefore the destruction of energy?

Last edited: Aug 18, 2013
2. Aug 18, 2013

Staff: Mentor

Things just don't stop moving, unless there is some interaction involved. Then you can say that the kinetic energy (which is only one kind of energy) of that body went to zero; but of course that energy didn't 'disappear', it was just transformed to something else.

3. Aug 18, 2013

Staff: Mentor

That is not the definition of energy. I think that you are refering specifically to kinetic energy, but there are other forms of energy as well. The total energy remains constant, but a specific form of energy, like kinetic energy, can certainly be eliminated.

4. Aug 18, 2013

Atwun

Both your responses makes sense and I agree with the idea that there the total amount of action in the universe remains constant ...that being said...you are also saying that matter in motion is NOT the definition of energy but only one kind of energy. However, whatever name you give to any one type of specific energy, whether it be chemical, electro-magnetic, radioactive...is there any type of energy that you can think of that does not deal with movement? Activity? Ultimately motion...and since all is made of matter...matter in motion?

5. Aug 18, 2013

mrspeedybob

I believe you may not have a clear distinction in your mind between energy and momentum. Momentum is also a conserved quantity. everything you have stated regarding your understanding of energy could be more accurately said of momentum.

6. Aug 18, 2013

Staff: Mentor

Potential energy.

7. Aug 18, 2013

Staff: Mentor

8. Aug 18, 2013

Atwun

My response to the first three responses after my last response is this:

As far as momentum goes....the first responder said I might not have a clear distinction between momentum and energy...I doubt this to be the case...I am clear about the reality that momentum and energy both have the common denominator of there being without increase or decrease in the ultimate amount of them. The amount of energy that exists as whole in the universe will is static as is the amount of momentum. That being said the word momentum is a means of measuring the force an object with energy, that is moving, contains. Momentum is a measurement of a particular aspect of "matter in motion" or "energy". Without matter in motion, the mass of an object has no ability to have an effect on anything that does not interact with itself. Mass that was moving and then moves not, can be said to be at at an energy level of zero. That is what one of the original responders to the start of this post said. They said though, that this is true of kinetic energy, where the energy of an object can exist within and then not exist at all. They suggested that there kinetic energy is just one form of energy.

So I asked for an example of a type of energy in which there is no mass in motion, no movement, no activity. I was suggesting that energy can be defined as matter in motion. One of the original responders to this post stated this is not true; that energy cannot be defined as matter in motion and why this is the case, why Energy does not equal Matter in Motion...I am still trying to understand.

To the second and third responders of my last response:

I know of the reality of the combination of the words "potential" and "energy". However, utilizing the word "potential energy"as a specific type of "energy" seems to me to have the same critical flaw as a person would have saying a person has a "potential mental disorder". A "mental disorder" is a "problem with the mind". There are many types of problems of the mind, from schizophrenia to sociopathic tendencies to depression and so on. A "potential mental disorder" is not a specific type of "problem with the mind" and "potential energy" is not a specific type of "energy". Perhaps, I am wrong. Negative feedback is more important to me than positive feedback so if someone knows of the problem in logic with this reasoning I would very much like to be told what it is. If you are suggesting that "potential energy", is a specific type of "energy" like kinetic, chemical or radioactive, I would most like to understand your rational. I am still searching for a specific type of energy that does not include movement, if energy is not to be defined as "matter in motion".

Last edited: Aug 18, 2013
9. Aug 18, 2013

Staff: Mentor

No, that's not what momentum is. (You are using terms loosely, terms that have specific meanings within physics.)

Don't confuse momentum with energy.

Not true.

Only the kinetic energy would be zero.

That's true.

You were given examples, the simplest being potential energy.

You yourself stated that total energy is conserved. Toss a ball up in the air. When it gets to the highest point, its speed is zero. What happened to that kinetic energy it had? (That's one way that potential energy comes in.)

10. Aug 18, 2013

Atwun

Most of your responses to the words I wrote I now understand and I appreciate your perspective on the way I wrote what I wrote.

I would like to know, if energy cannot be defined as matter in motion, how can we define it? Any word that we are to use the word energy with must have something in common with all the other words we use the word energy with. For the word "energy" to have any true meaning at all there must be a common denominator with all things that are said to be or have "energy".

Of course, one way out of trying to define the word is to simply write : Energy equals mass times the speed of light squared. This equation allowed for the generation of the most powerful of all human made energy sources. Nuclear fission, the essence of the power of a nuclear bomb or power nuclear power plant works by causing a chain reaction in atomic particles that knocks other subatomic particles around. A chain reaction that releases thermal energy, sound energy, radioactive energy, and all this energy is a result of matter at some level moving. Am I wrong to think this?

Is it not true that all things that we say have energy are in same way active and all those things that we say have potential energy have the ability to activate? Is not all activity a form of motion? Matter in motion?

11. Aug 18, 2013

Staff: Mentor

One common definition of energy is the ability for one system to perform work on another system.

Einsteins equation is NOT a definition of what energy is. It doesn't tell you what it does, it merely allows you to calculate the energy content of an object based on its mass and momentum.

Light has energy, yet it is not matter in motion.
Gravitational waves have energy as well, yet they are not matter in motion either.

12. Aug 18, 2013

Staff: Mentor

Neither the action nor the Lagrangian is conserved.

The only other type of energy that deals with movement besides kinetic energy is thermal energy. All other types of energy do not deal with movement and can be positive even when nothing is moving. Several good examples have already been given.