There are two ways that a substance can respond to an electric field.

In one case the atoms or molecules stretch as electrons are pulled toward the positive and pushed away from the negative. These substances are called insulators or dielectrics. They are useful in shielding from the electricity as in coating wires and as material placed between thin sheets of conducting material in capacitors.

On the other hand are conductors. These substances are usually metallic. Metals are good conductors because of their crystal structure in which electrons are loosely attached to the parent atoms and can easily move from one atom to another. When electrons do this, we say that a current is flowing like an electrical fluid.

Even the best conductors such as silver, copper and aluminum have a certain resistance to the flow. This is due to a disordered movement of electrons as they bump into one another and generate heat. In extreme cases, such as with nichrome, used in heating elements in toasters and hair dryers, the wires become red hot as electrical energy transforms into heat and your morning toast gets brown and delicious.

In most applications heat is an undesirable byproduct of the current, and metallurgists try to find alloys or ceramics that have the lowest resistance. The lower the resistance the less heat is generated and lost to the system. High voltage power lines, rail systems and other high energy systems lose a significant amount of energy to heat.

In a conventional superconductor the situation is different. The electronic fluid does not flow as individual electrons. Instead, the electrons form pairs known as Cooper pairs caused by an attractive force between electrons from the exchange of phonons. This pairing is very weak and thermal agitation will destroy it.

Because they are in a quantum state, the energy spectrum of this paired electron fluid possesses an energy gap. Therefore, if the gap is larger than the thermal energy of the lattice the fluid will not be scattered by the lattice. The Cooper pair fluid is thus a superfluid, and it can flow without dissipating energy as heat.

Today superconductive systems are in use in many industrial settings where super-strong magnetic fields are necessary. MRIs, maglev rails and particle colliders are examples. These systems are very expensive to operate since they must be cooled to a few degrees above absolute zero to become superconducting.

This is done with liquefied helium, which is expensive to make and vaporizes quickly if exposed to conditions warmer than minus 450 degrees Fahrenheit.

The holy grail of researchers is a room-temperature superconductor. Imagine if electricity could be transmitted without loss across hundreds of miles, or if MRI machines did not have to procure and store supercold liquid helium.

From time to time a group of researchers announces the development of a room-temperature candidate for superconductivity. This happened in July with the announcement by South Korean researchers of hopes that LK-99 — a compound of copper, lead, phosphorus and oxygen — would prove to be the first superconductor that works at room temperature and ambient pressure.

But it was yet another false alarm. Instead, studies have shown that copper sulfide impurities in the LK-99 material were responsible for the false positives.

Research goes on. If a substance were to be found that is truly superconducting at room temperature and ambient pressure it would revolutionize the world like nothing other, short of fusion-generated electricity.