Defining Energy


The palpable universe and how we perceive it and know about it is all about transformation of energy (see also the post “Change and Suffering, Phantoms and Dreams”).

Energy patterns upon energy patterns.

We know energy is fundamental. Besides our intuition and use of the word very freely in common parlance, everyone knows that Einstein informed us that things are convertible to energy and energy to things:


E= energy, M= mass, c= the speed of light. Since c (the speed of light) squared is a constant, just a number that doesn’t change but makes the units work out:

Energy IS mass (stuff/things). Mass IS energy.

But you knew that part of the equation, probably since you were a kid. The other part of the equation Einstein wrote that you may not know addresses energy for particles that don’t have mass, like photons, and involves their momentum.

Momentum is how much oomph something has. The oomph it has when it interacts with something else.

For things with mass, like cars and people, momentum is mass time velocity. Velocity is the rate of change of position [speed] and direction. A big thing moving fast right at you has more momentum than a small thing moving slow-moving obliquely to you that will hit you with a glancing blow.

But photons, particles of light, as well as some other particles, have no mass, but have energy. They have oomph, they have momentum. Massless entities, things without thingy-ness, without substance, ghosts as it were, without form, can interact with massive entities with thingy-ness, form and substance.  Photons respond to the force of gravity. They can kick electrons out of atoms under the right conditions. They can get your atoms and molecules moving (resulting in increased temperature). They can cause chemical bonds to break if the photons are energetic enough (x rays and gamma rays are made up of photons); think radiation sickness, mutations and cancer! Their energy can be transformed into other forms of energy; think solar energy, where energy in photons from the sun is transformed into electrical energy (the movement of charged particles like electrons).

But still, Einstein’s famous formula of general relativity notwithstanding, what IS Energy?

“Energy is one of the most important concepts in science… Yet we cannot give a simple general definition of energy in only a few words.” “..we could define energy in the usual way as “the ability to do work”. This simple definition is not very precise, nor is it valid for all types of energy.” [University Physics for Scientists and Engineers Giancoli 2000 pg 155-156]:

“There is a fact, or if you wish a law, ….the conservation of energy. It states that there is a certain quantity, which we call energy, that does not change in the manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says that there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or anything concrete, it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same.

It is important to realize that in physics today, we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount…. It is an abstract thing in that it does not tell us the mechanisms or the reasons for the various formulas. “[His italics][Richard Feynman Lectures on Physics [4-1, 4-2]

So is energy anything is science? Is it just a placeholder, an accounting trick?

Kind of!

Energy is not a substance we can measure directly. You can’t scoop out a handful of it and smell it, touch it, weigh it. You can’t put a measuring stick into the universe’s gas tank to see how empty or full it is. It is probably infinite anyway, so no dipstick can serve!

The energy in the universe is certainly vast (well, if infinite, that is an understatement).

To give an example, there are particles that pop into and out of existence so rapidly we can’t measure them directly, we can’t use them to do anything useful but we can measure their effects indirectly. More on these in later posts on quantum mechanics and cosmology. They are called virtual particles. The physicist Leonard Suskind wrote in his book “The Cosmic Landscape” that the energy in the virtual photons in an area the size of your fingertip is greater than the energy all the stars that there are now in the visible universe will expend in their entire lifetime.

This doesn’t apply just to empty space,somewhere beyond the blue sky, it applies to your actual finger tip! Since atoms are 99.9999% empty space, so are you. Space filled with virtual photons. And you occupy the space of thousands of fingertips, enough for all the stars that have existed in the visible universe for 14 billion years with plenty to spare. Multiverses worth. And there is a lot of fingertips of space out there (maybe an infinite number of fingertips of space!).

What we measure is changes in energy. We follow what happens to the energy when things happen. We can measure changes in kinetic energy, the energy of movement, or changes in potential energy. Changes in movement are pretty easy to visualize, potential energy may be a bit more difficult. Changes in potential energy are due to changes in the positions of things relative to each other, say changes in electrical potential energy due to a separation of charged particles or gravitational potential due to changes in the positions of two masses relative to each other.

Energy is fundamental to all of mechanics, including quantum mechanics. Mechanics in physics relates to movement, and movement is what defines time and space. That is where the job title “mechanic” comes from: it’s someone who works with moving parts. Nothing “happens” in time and space but that there is movement of something.

Before and after, here and there.

Any event in the palpable universe, in the universe of the senses, of the relative, of conditions, of causes, of karma, of experience, of the material, of the mental, is an event because of movement (really; think about it).

Movement is the ground state of things. Everything moves. Always.

Nothing is static. Everything interacts constantly with everything else, so there is always movement. If something appears static, that is just a balancing act of opposing motions.

All things move.

If it doesn’t seem to move it is an illusion; it won’t last.





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