# Why does energy impart the ability to do work?

I am not sure if I am asking a metaphysical question but I really have a problem understanding the core of this concept of energy and its ability to drive almost everything we see in the universe, whether it be cells in the body, electrons in atoms, movement of everyday objects upon mechanical force.

Like what it is about energy that it can give electrons the ability to move perennially around the nucleus? What it is about energy that it can allow the enzyme to move around in cells and replicate DNA etc?

I don’t know if I am asking an impossible question or if the premise of my question is faulty but can anyone please give me a way to conceptualize this word “energy”? Thank you.

## 3 Answers

This question, as asked, is a little circular. Energy is defined as the ability to do work. So literally you are asking “Why does the ability to do work impart the ability to do work?”

Energy isn’t a separate thing, it’s own independent entity. It is a way of describing a system. The laws of physics permit some systems to exert a force over a distance. Such systems are described as having energy. The system can do work by the laws of physics governing the system, and the amount of work the system can do is its energy.

To help conceptualize energy it is useful to think of a spring. (Many of the laws of physics resemble springs in some important ways). A spring follows Hooke’s law which says that a spring has an equilibrium length and as you stretch it or compress it the spring produces a force pushing back towards equilibrium. When a spring is stretched Hooke’s law imparts the ability to exert a force over a distance. As such, the spring is described as having energy. It is Hooke’s law that provides the ability to do work, energy simply describes and quantifies that fact.

• Okay. I am not sure if I understood it well, but I would ask then that what is it about energy that it can exert force on another entity, whether through contact or distance? Like if my hand makes contact with a ball, does the ball move because energy is "magically" being transferred to the ball through force, upon which the ball moves a certain distance, giving evidence of work done?
– TLo
Aug 16 '20 at 1:52
• You are thinking about energy like it is it’s own independent entity again. Energy doesn’t exert force. The system exerts the force. Energy is just a description of the system. A tall man may bump his head on a door frame because he is so tall, but it is the man that bumps his head, not the tall. Energy is like tall, it is a description of something else.
– Dale
Aug 16 '20 at 1:59
• Dale, thanks a lot for your explanation. It changed the way I think of the word.
– TLo
Aug 16 '20 at 18:23

One abstraction that has helped me understand energy(E) is: change. So the ability to do work, is also energy. Water stored in a reservoir has potential energy, the ability to do work on a turbine, and different types of work can be quantified and measured: mechanical, chemical, thermodynamic (heat), hydrodynamic, etc. Willing to bet it could also be applied to social change! I'm sure some social scientist has applied some mathematical model to quantify social movements, disruption, economics, epidemiology (disease). Your body stores potential energy in fat cells for later consumption, and uses up energy in the form of burning calories, metabolizing food, sweating, giving off heat (measured in BTUs) etc, all the chemical processes required to keep you alive.

So energy is a representation of change in a given context using a set of variables and values.

I want to address this:

Like what it is about energy that it can give electrons the ability to move perennially around the nucleus?

It is not energy that keeps the electron at an energy level, but quantum mechanics, which mathematically imposes fixed energy levels. The electron in an orbital around an atom does not change energy , unless interacting with other particles. Then energy levels can be changed by the energy carried out or brought in by other particles

What it is about energy that it can allow the enzyme to move around in cells and replicate DNA etc?

A more complicated form of the argument above, since enzymes and dna are at the quantum mechanical microscopic frame. Energy levels and exchange of energy through interactions