What exactly is energy....without using symbols and metaphors?

Energy is often described/explained/thought of in terms of symbols and metaphors, but what exactly is it? Molecules that are very hot have lots of kinetic energy, but what makes them vibrate/move in such a way? What exactly is the energy doing. I'm having trouble asking my question, so hopefully someone else will understand what I'm trying to ask --and will be able to provide an answer.

 

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As far as I know its just a number - a mathematical function that has the useful property of being 'conserved' (ie its time derivative is zero). This makes some problems a lot easier to solve.

 

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Two types of energy I know are potential and kinetic.

When you say 'Potential energy' you really mean a potential energy function, which is associated with a conservative force and is path independent. And then there is kinetic energy, which depends on the work-ke theorem. im not sure what you mean by without 'symbols and metaphors' since energy is defined in mathematical terms (symbols).

 

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A material having energy (chemical, potential, kinetic, etc) can be described as NOT being in its lowest energy state. Simply put the laws of thermodynamics (entropy) will drive things to their lowest energy state doing work in the process. This work is characteristic of an item having (and losing) energy.

So I would say that energy is the capacity to do work of some sort. It is categorically NOT a substance in itself that pervades the universe

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http://www.websters-dictionary-online.org/definition/energy

Energy certainly is *not* just an abstract concept like mathematics. If you really think so, try sticking a fork into an electrical socket!

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Everything is energy because all matter irrespetive of state is a form of energy. Human power, chemical, mechanical, e.t.c. Some would say its the inverse of matter but i'd say its the function to all changes, all change are subject to a certain parameter such as energy. If i'm going to run 5 miles, it depends on how much energy I have and the slope of the road. If I'm going to create a new computer the demand is what must motivate me, its the energy. This is ultimately why people speak of the first universal function when talking of the creation of the universe. Sorry if I am using what may seem as metaphors but its the underling function of all change, and change is all there is.

 

Chatha, are you refering to E=mc^2 when you say that energy is everything? Also, my education must be remiss, but what is the "first universal function" when you refer to the "creation of the universe"?

 

I think you are asking if energy is a cause, an effect or other entity.
I think it's a property associated with the state of a particle.
It's like this, perhaps:
Energy does not cause something to move but a moving object possesses energy.

 

Physics defines energy as the capacity of a physical system to do work.

This work could entail a battery lighting a lightbulb, the chemical energy stored in charcoal to bbq some ribs or the potential energy of water to generate hydroelectric power. These systems have the capacity to do work. Energy is not a mathematical abstract, not the "function to all changes" (which is meaningless) but it can be well described as the property of a physical system.

 

why is energy the function of all changes meaningless? Care to demonstrate how all changes don't require and follow energy?

 

Sometimes I think I am chating with high school kids on this forum. What's worse are people with no imagination. In a battery electrons move (change position) and thier velocity depends of the current passing through it. In Charcoal energy is released from carbon chains as heat, again another change. Water used in dams flows with great velocity and then slows down, again another change. No matter what form of eergy you are using there is a change, either of state or position. Simply put without possibility of change, there will be no energy and no need for it. Yes, you defined energy as property of a physical system, correct you can measure the energy of a system. I want to to however note that in all systems there is a change going on; in the energy source itself, the body in question, and the system as a whole. Its all about change, thats all there is in the universe, the dimensions of the change is however subject to the rate and path of change of the system, which is pretty much energy.

Example of how energy determines path of change
For example you never see someone migrating to a place with little food dupply, instead you see them migrating to a place with plenty food supply. Also electrons migrate to positive charges.

Example of how energy determines rate of change
Amount of cycles per sec a speed cyclist peddles his bike with human power. Speed of electrons in a circuit connected to a bulb

It also determined the amount of change
Nuclear explosions-all explosions in general

Hence E = mc^, an equation representing change

All energy changing to matter, and all matter changing back to energy, change is the only constant thing happening in the universe. Everything moves for a reason, follows a certain path, and has a rate of change- all determined by energy.

 

We know there is a phenom known as change, we also know not all change is the same, energy is the reason for this difference. Thats why energy is the function of all change.

 

Maybe its my inability to express my question, but so far my question hasn't been answered.

Say you heat up a container full of a gas. Energy will be transferred from the heat source to the gas, and thus the kinetic energy increases. But what exactly is happening. What is being transfered. Try to explain it to me without using the word 'energy.'

 

There is only one energy: will.

 

Ultimately what is being transferred is paticle motion. The molecules of the heating element are rapidly vibrating (that's why it's hot). Gas molecules collide with these rapidly vibrating molecules, and come out of the collision moving faster than when they went in. The fast moving gas molecules then recoil and collide with slower moving gas molecules. This continues as the average speed of the gas molecules goes up. This corresponds to a temperature increase.

I completely agree with that. Whenever the question "what is energy" comes up I always give the same response: Energy has no reality apart from its mathematical dependence on measureable state variables. You don't actually measure an object's kinetic or potential energies, you measure its associated state variables (velocity and position, respectively).

 

Hi Possumking,

This question is a perrenial favorite, so I would add a word of caution before I answer. Please be careful not to assume that just because we can't package energy up into a simple four word definition that we don't understand what it is. This is not the case, of course, as most physicists know exactly what energy is. The concept of energy is ultimately a tool that we invented to understand the world around us. This is not a definition of energy, and I don't intend it to be. The whole point of energy is that it can be many things. It is inherently vague, and that's why it's so useful.

Some of our tools, like the notion of length, say, are inherently close to our perception, and we feel comfortable with them. Length is somehow a quantification of the primitive notion that there is "here" and "there." The notion of energy represents a higher order kind of tool. It doesn't correspond so simply to our direct experience because I can't point to some primitive notion you have and say, "There, that's energy!" It's an abstraction, if you like, but it enables a unified description of many diverse phenomena. This is the way I would suggest you think about energy: as a tool. It's one more way to organize our understanding of the universe.

P.S. "Exact" definition: Energy is the generator of time translations. Now you see why no one gives you the exact definition! It typically takes years of intensive training to comprehend what this statement really means.

 

Ah, well I guess thats good enough to hold me for a while.

About this time translations business....intensive training? Do you mean intensive math courses and years of studying? Or is this some sort of meditation bullshit?

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Please excuse my ignorance.

 

Wow. That's a pretty good way of thinking of it.

 

Interesting but totally useless Chatha. What predictions can you make with your metaphysical assertions about "change". In case you have gone no furhter than a first degree in physics you may not know that the ability to make predictions is a critical test of any theory. Confusing what is a relatively simple issue with low-level philosophical blitherings helps no one.

 

Haha, please feel free to question me further if you aren't satisfied! I told you one way I look at energy, but not much else. przyk gave a more concise statement of roughly what I was trying to get across. I can try to say more if you want.

No meditation bullshit here. I am a classically trained theoretical physicist, and I meant you need to learn and digest several mathematical and physical concepts. I would guesstimate that it takes the average physicist-in-training roughly four years of undergraduate work and a year or so of graduate school to really grasp deep down what that statement means. Then again, it isn't really that hard. It already shows up in "advanced" formulations of classical mechanics which one could easily learn as an undergraduate or as an intrepid independent.

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I didn't see any ignorance that needed excusing. Asking questions is great.