Zero-Point Energy

Quantum physics predicts the existence of an underlying sea of zero-point energy at every spot in the universe. This is different from the cosmic microwave background and is also referred to as the electromagnetic quantum vacuum , since it is the lowest energy state of otherwise empty space. This energy is so enormous that most physicists believe that even though zero-point energy seems to be an inescapable consequence of elementary quantum theory, it cannot be physically real. However, a minority of physicists accept it as real energy that we cannot directly sense because it is the same everywhere, even inside our bodies and measuring devices. From this perspective, the ordinary world of matter and energy is like a foam atop the quantum vacuum sea. It does not matter to a ship how deep the ocean is below it. If zero-point energy is real, there is the possibility that it can be tapped as a source of energy or be harnessed to generate a propulsive force for space travel.

New Propulsion for Space Travel

The propeller or the jet engine of an aircraft pushes air backwards to propel the aircraft forward. A ship or boat propeller does the same thing with water. On Earth there is always air or water available to push against. But a rocket in space has nothing to push against, and so it needs to carry propellant to eject in place of air or water. As the propellant shoots out the back, the rocket reacts by moving forward. The fundamental problem is that a deep-space rocket would have to start out with all the propellant it would ever need. This quickly results in the need to carry more and more propellant just to propel the propellant. The breakthrough needed for deep-space travel is to overcome the need to carry propellant at all. How can one generate a propulsive force without carrying and ejecting propellant?

One possibility may involve a type of Casimir force. The Casimir force is an attraction between parallel metallic plates that has now been well measured. It can be attributed to a minutely tiny imbalance in the zero-point energy between the plates and the zero-point energy outside the plates. This is not currently useful for propulsion since it just pulls the plates together. If, however, some asymmetric variation of the Casimir force could be found, one could use it to sail through space as if propelled by a kind of quantum fluctuation wind. This is pure speculation at present.

The other requirement for space travel is energy. A thought experiment published by physicist Robert Forward in 1984 demonstrated how the Casimir force could in principle be used to extract energy from the quantum vacuum. Theoretical studies in the early 1990s verified that this was not contradictory to the laws of thermodynamics (because the zero-point energy is different from a thermal reservoir of heat). Unfortunately, the Forward process cannot be cycled to yield a continuous extraction of energy. A Casimir engine would be one whose cylinders could fire only once, after which the engine becomes useless.

The Heisenberg Uncertainty Principle

The basis of zero-point energy is the Heisenberg uncertainty principle, one of the fundamental laws of quantum physics. According to this principle, the more precisely one measures the position of a moving particle, such as an electron, the less exact the best possible measurement of its momentum (mass times velocity) will be, and vice versa. The least possible uncertainty of position times momentum is specified by Planck's constant, h. A parallel uncertainty exists between measurements involving time and energy. This minimum uncertainty is not due to any correctable flaws in measurement but rather reflects an intrinsic quantum fuzziness in the very nature of energy and matter.

A useful calculational tool in physics is the ideal harmonic oscillator: a hypothetical mass on a perfect spring moving back and forth. The Heisenberg uncertainty principle dictates that such an ideal harmonic oscillator—one small enough to be subject to quantum laws—can never come entirely to rest, because that would be a state of exactly zero energy, which is forbidden. In this case the average minimum energy is one-half h times the frequency, hf/2.

The Origin of Zero-Point Energy

The zero-point energy is electromagnetic in nature and is like ordinary radio waves, light,X rays , gamma rays, and so forth. Classically, electromagnetic radiation can be pictured as waves flowing through space at the speed of light. The waves are not waves of anything substantive but are ripples in a state of a theoretically defined field. However, these waves do carry energy, and each wave has a specific direction, frequency, and polarization state . This is called a "propagating mode of the electromagnetic field."

Each mode is subject to the Heisenberg uncertainty principle. This means that each mode is equivalent to a harmonic oscillator. From this analogy, every mode of the field must have hf/2 as its average minimum energy. This is a tiny amount of energy, but the number of modes is enormous and indeed increases as the square of the frequency. The product of the tiny energy per mode times the huge spatial density of modes yields a very high theoretical zero-point energy density per cubic centimeter.

From this line of reasoning, quantum physics predicts that all of space must be filled with electromagnetic zero-point fluctuations (also called the zero-point field), creating a universal sea of zero-point energy. The density of this energy depends critically on where in frequency the zero-point fluctuations cease. Since space itself is thought to break up into a kind of quantum foam at a tiny distance scale called the Planck scale (10⁻³³ centimeters), it is argued that the zero-point fluctuations must cease at a corresponding Planck frequency (10⁴³ hertz). If this is the case, the zero-point energy density would be 110 orders of magnitude greater than the radiant energy at the center of the Sun.

Inertia, Gravitation, and Zero-Point Energy

Theoretical work from the 1990s suggests a tantalizing connection between inertia and zero-point energy. When a passenger in an airplane feels pushed against his seat as the airplane accelerates down the runway, or when a driver feels pushed to the left when her car makes a sharp turn to the right, what is doing the pushing? Since the time of English physicist and mathematician Isaac Newton (1642-1727), this pushing feeling has been attributed to an innate property of matter called inertia. In 1994 a process was discovered whereby the zero-point fluctuations could be the source of the push one feels when changing speed or direction, both being forms of acceleration. The zero-point fluctuations could be the underlying cause of inertia. If that is the case, then people are actually sensing the zero-point energy with every move they make. The zero-point energy would be the origin of inertia, hence the cause of mass.

The principle of equivalence would require an analogous connection for gravitation. German-born American physicist Albert Einstein's general theory of relativity successfully accounts for the motions of freely falling objects on geodesics (the shortest distance between two points in curved space-time ), but it does not provide a mechanism for generating a reaction force for objects when they are forced to deviate from geodesic tracks. A theoretical study sponsored by the National Aeronautics and Space Administration has demonstrated that an object undergoing acceleration or one held fixed in a gravitational field would both experience the same kind of asymmetric pattern in the zero-point radiation field, the asymmetry yielding the inertia reaction force or weight, respectively. The weight one measures on a scale would be due to zero-point energy.

The possibility that electromagnetic zero-point energy may be involved in the production of inertial and gravitational forces opens the possibility that both inertia and gravitation might someday be controlled and manipulated. Imagine being accelerated from zero to light speed in a fraction of a second without experiencing any devastating G forces . Such a science fiction-like possibility could someday become real and have a profound impact on propulsion and space travel.

see also Accessing Space (volume 1); Power, Methods of Generating (volume 4).

Bernard Haisch

Bibliography

Haisch, Bernard, Alfonso Rueda, and H. E. Puthoff. "Inertia as a Zero-Point-FieldLorentz Force."Physical Review A 49 (1994):678-694.

Rueda, Alfonso, and Bernard Haisch. "Contribution to Inertial Mass by Reaction of the Vacuum to Accelerated Motion."Foundations of Physics 28 (1998):1,057-1,108.

——. "Inertia Mass as Reaction of the Vacuum to Accelerated Motion."Physics Letters A 240, no. 3 (1998):115-126.