Today’s science knows precious little about negative energy. The best example we have of creating negative energy in the laboratory is the Casimir effect, which we briefly discussed previously, but will now discuss in detail. Let us start by discussing the energy associated with a vacuum. Vacuums contain energy. One simple experiment to prove this is to take two electrically neutral metal plates and space them closely together in a vacuum. They will be attracted to each other (i.e., the Casimir effect). At approximately 10 nm (i.e., 1/100,000 meters) separation, the plates experience an attraction force of about one atmosphere (i.e., typically, the pressure we feel at sea level on Earth). What is causing this force?

The energy in a vacuum is termed “vacuum energy.” Surprisingly, it appears to obey the laws of quantum mechanics. For example, the energy will statistically vary within the vacuum. When the vacuum energy statistically concentrates, it gives rise to virtual particles, which is termed a “quantum fluctuation.” When the metal plates are spaced closely, relatively few virtual particles can form between the plates. A much larger population of virtual particles can form around the plates. This larger population of particles exerts a force on the outside of the plates. This force is the Casimir-Polder force, and it pushes the plates together. However, another strange physical phenomenon is also occurring between the closely spaced plates. In quantum mechanics, every particle has a “zero-point energy.” Even a vacuum is said to have a zero-point energy. The zero-point energy, or the “ground state,” is the lowest energy level that a particle or a vacuum may have. By reducing the space between the plates, some physicists believe we are reducing the normal zero point energy of the vacuum between the plates. When this occurs, those physicists argue the vacuum energy between the plates is negative energy (i.e., below the zero-point energy).

The scientific community is not in complete consensus regarding the properties or even the existence of negative energy. Physicists are able to mathematically model negative energy and use those models to make predictions regarding the theoretical behavior of negative energy. While the mathematical models do not prove the existence of negative energy, it is instructive to consider their predictions, and their implications to time travel. Here are the salient features of negative energy based on the mathematical modeling:

• Negative energy implies the existence of negative mass. This, of course, begs a question. What is negative mass? Negative mass is a hypothetical concept in theoretical physics. Anglo-Austrian mathematician and cosmologist Hermann Bondi suggested its existence in 1957. If it exists, it is the negative counterpart of normal (i.e., positive) mass and exhibits unusual properties. For example, normal masses exhibit attractive forces, known as gravitational attraction. Negative masses would exhibit repulsive forces. However, be careful not to equate negative mass with antimatter. The vast majority of the scientific community holds that antimatter is still positive mass. Based on this consensus, they predict antimatter would exhibit the same properties as positive mass. For example, two antimatter particles would exert an attractive force on each other, not a repulsive force. The implications of negative mass on time travel are ambiguous, since the existence of negative mass itself is ambiguous.

• Several in the scientific community suggest that a negative energy vacuum would allow light to travel faster than a normal positive energy vacuum. If this theory proves to be correct, it could have major implications for time travel. For example, there is speculation that this property may allow people to travel faster than the speed of light in a negative-energy vacuum bubble. Previously, we have discussed that as a mass approaches the speed of light, time dilates (i.e., time slows down for the mass). If the mass exceeds the speed of light, the implication is that it can travel into the past. We will discuss this further in the next chapter.

• Stephen Hawking and other physicists suggest that negative energy is required to stabilize a “traversable wormhole,” an entity that would allow a person, object, or information to travel between two points in time or space. Wormholes are a hypothetical shortcut between two points in time or two points in space. There are solutions to Einstein’s general equations of relativity suggesting the theoretical existence of wormholes. However, we have no observational evidence that they exist in reality.

Until we can find a way to produce negative energy and apply it experimentally to determine its effect on time, we can only speculate.

Source: How to Time Travel (2013), Louis A. Del Monte