I watch a lot of science documentaries on TV. Many (but not most) are well done, but only rarely is there one that does not commit a serious error, either by stating facts incorrectly or out of context, misrepresenting facts, making erroneous conclusions from facts, or misusing or misunderstanding physical laws.

One of the most egregious regular errors concerns the supposed creation of energy.

A program about the large hadron collider at CERN explains how superconducting magnets accelerate protons in opposite directions around a huge underground ring 17 miles in diameter. According to the TV, a huge amount of energy is "created" when the machine focuses the two proton beams to cause collisions.

A different program, one about stars, says that a star "creates" energy when it explodes as a supernova.

Both are wrong. Energy is not created in either case. Energy is a conservative property, which means it cannot be created or destroyed. In both cases, energy is already present; it is merely invisible.

Similarly, at the top of the stairs, I have more gravitational potential energy than at the bottom. A photograph would confirm that there is nothing visibly changed about me. There is no information about how I got there, and no way to determine how much energy I have. I could calculate it. I could demonstrate a skinny cannonball into the pool. Then the splash of water would illustrate that the energy did work on the water, but in no way does the splash create the water.

The magnetic field that accelerates the protons around the ring at CERN gets its energy from electricity supplied to it. That energy comes from a power station, which gets its energy from fossil fuel; or from wind, water, waves or tides that get their energy directly from the sun.

The sun gets its energy from nuclear bonds, the energy for which came originally from the Big Bang and crystallized into protons, which when crammed together by gravity allowed the strong nuclear force to take over and begin fusion.

All of the energy we use ultimately comes from this self-sustaining fusion. Here on Earth biological and physical processes have transformed it into chemical, mechanical, electromagnetic, thermal or radiant energy.

Energy is a way of storing work. A gain in energy is equal to work done from outside the system. In a conservative system, no net work is done, so all of the energy changes within the system add up to zero. That is the same as saying that energy lost in one place in the system results in energy gained somewhere else in the system in equal amounts. It is like pouring water from one glass to another. If no water is lost or added then the loss of water in one glass equals the gain in another.

The next time you hear that some process or activity has created energy, this knowledge will allow you to understand it actually has released energy that was already there in some form.

Richard Brill is a professor of science at Honolulu Community College. His column runs on the first and third Fridays of the month. Email questions and comments to brill@hawaii.edu.