What exactly is Energy?

Question

Now, I nkow the school taught definition - "Ability to do work". But, energy can only be observed in an indirect fashion, when it is a cart that moves when you push it, or it is supernova happening in the skies. These are just "effects" of energy.

Then there is Light, Sound etc. - different forms of energy... But, what is energy in its most basic abstract form/sense. What is its smallest measurement?

Maybe, I am not making any sense here, but I could never quite "grasp" the concept of energy.

Answer 1

I agree it's confusing.

wilipedia:

In physics and other sciences, energy is a scalar physical quantity that is a property of objects and systems which is conserved by nature.

Energy is often defined as the ability to do work.

Several different forms of energy, including kinetic, potential, thermal, gravitational, sound energy, light energy, elastic, electromagnetic, chemical, nuclear, and mass have been defined to explain all known natural phenomena.

While one form of energy may be transformed to another, the total energy remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the earth.

Answer 2

The broadest, most abstract, basic sense is "the ability to do work."

You may want to think about why something has POTENTIAL energy.

The "why" is also a basic sense.

The smallest measurement is dependent upon the sensitivity of the measuring instrument.

Answer 3

Energy is a measure of an object's ability to do work. Even to the littlest molecules, there is energy. Since molecules also "move" from one position to another, although minimal.

Answer 4

Energy is the ability to move from here to there. Simple. It can be in moving your body to moving a mountain to moving a couch. It can be moving an electron from atom to atom. It can be bumping an atom into another atom, this is heat by the way. The cardinal rule is that energy can't be created nor destroyed... You may change the word energy with the phrase "ability to move" and you will mean the same exact thing.  

Answer 5

Energy is a property of things, not a thing itself. You might as well ask what the most basic, elemental form of the colour red is.

Answer 6

something that feeds off what you put in

Answer 7

The capability to do work or cause a change.

This commonplace definition fails to make it clear we are talking about capability, not the work or change itself.  Mirriam defines capability as:

3. the facility or potential for an indicated use or deployment [See source.]

So, without loss of defintiion, we could define energy as the potential to do work or cause a change.  But this points out some real issues with the commonplace definition.  Check this out.

If we define potential energy as the potential capability to do work or cause a change, we are logically saying potential energy is the potential potential to do work or cause a change.  And that is clearly redundant.

My point is this...technical definitions are typcally coined by technical people who have little clue about what makes a solid, consistent definition.  All the scientific disciplines are filled with technical, often arcane, definitions that do not hold up well under scrutiny.

To your last point about strings.  Just because strings are small (10E-33 cm), that does not mean they represent minimal energy.  In fact, the minimal energy of a string has been guesstimated at about 1,000 KW.  [Sorry don't remember the source.]  We don't see that energy in our 4D universe (3 spatial plus time) because, according to string theory, it is contained in 11D space-time and only a portion of it and its energy exists in our space-time. [See source.]

Answer 8

energy in simple terms is "the ability to do work".