Posted on 02/28/2003 2:59:02 PM PST by sourcery
Quantum physics predicts the existence of an underlying sea of zero-point energy at every point 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 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, and so is subtracted away in calculations.
A minority of physicists accept it as real energy which we cannot directly sense since 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 the zero-point energy is real, there is the possibility that it can be tapped as a source of power or be harnassed to generate a propulsive force for space travel.
The propellor or the jet engine of an aircraft push air backwards to propel the aircraft forward. A ship or boat propellor 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. The fundamental problem is that a deep space rocket would have to start out with all the propellant it will ever need. This quickly results in the need to carry more and more propellant just to propel the propellant. The breakthrough one wishes 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?
There is a force associated with the electromagnetic quantum vacuum: the Casimir force. This force is an attraction between parallel metallic plates that has now been well measured and can be attributed to a minutely tiny imbalance in the zero-point energy in the cavity between versus the region outside the plates. This is not useful for propulsion since it symmetrically pulls on the plates. However if some asymmetric variation of the Casimir force could be identified one could in effect sail through space as if propelled by a kind of quantum fluctuation wind. This is pure speculation.
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 (Phys. Rev. B, 30, 1700, 1984). Theoretical studies in the early 1990s (Phys. Rev. E, 48, 1562, 1993) verified that this was not contradictory to the laws of thermodynamics (since 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 only fire once, after which the engine become useless.
ORIGIN OF ZERO-POINT ENERGY
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 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, since 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.
Radio waves, light, X-rays, and gamma rays are all forms of electromagnetic radiation. 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 in fact ripples in a state of a field. 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. To understand the meaning of this, the theory of electromagnetic radiation is quantized by treating each mode as an equivalent harmonic oscillator. From this analogy, every mode of the field must have hf/2 as its average minimum energy. That 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 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 cm), it is argued that the zero point fluctuations must cease at a corresponding Planck frequency (1043 Hz). If that 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.
CONNECTION TO INERTIA AND GRAVITATION
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 Newton, this 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 we are actually sensing the zero-point energy with every move we make (see origin of inertia).
The principle of equivalence would require an analogous connection for gravitation. Einstein's general relativity successfully accounts for the motions of freely-falling objects on geodesics (the "shortest" distance between two points in curved spacetime), but does not provide a mechanism for generating a gravitational force for objects when they are forced to deviate from geodesic tracks. It has been found that an object undergoing acceleration or one held fixed in a gravitational field would experience the same kind of asymmetric pattern in the zero-point field giving rise to such a reaction force. The weight you measure on a scale would therefore be due to zero-point energy (see gravitation).
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. This could have a profound impact on propulsion and space travel.
Owing to a reduction in 'pressure' above the airfoil as the airfoil moves through the air (and actually, it's a resultant 'push' that occurs from the air *below* the airfoil, but, it is not simply the 'thrust' or a 'push' developed by the prop against the air that produces the resultant *force* ...)
I believe it is more correctly stated that you posted to me first.
And where does this pressure gradient come from? What does Newton's Third Law of Motion REQUIRE to be the case, given the interactions between the propellor and the air molecules, via which that pressure gradient arises?
Background for lurkers:
From the CERN Courier
The new Ekpyrotic theory has grown out of string and super string theory that says there have to be eleven dimensions. We live in the first four of 3-dimensional matter plus time. The 5th dimension is the one in which, the new theory goes, a cataclysmic event took place that ended up creating the universe we are now living in. Dimensions 6 through 11 are like scaffolding behind the scenes upon which our 3-dimensional theater plays out. Dimensions 6 through 11 are also tiny and curled up into little "strings" which are too small to see, but without them the universe could not exist.
String theory says that dimensions 1 through 4 "float," so to speak, in the 5th dimension. The new theory suggests that not only is our universe floating in the 5th dimension, but the 5th dimension can have waves in it just like the ocean. Further, one or more of those 5th dimensional waves can become a soliton - meaning, a wave can form that keeps on going as a wave and does not collapse. If such a 5th dimensional soliton wave should come in contact with a 4-dimensional universe such as ours, what would happen? That's what these cosmologists and mathematicians have been working on. Rather than calling this a universe and the soliton wave a wave, theorists today now refer to large scale mathematical features in different dimensions as "branes." The term originated from discussions about "membranes" between or in different dimensions.
Recently in a meeting at the Space Telescope Science Institute in Maryland, this new theory about the creation of our universe from a 5th dimensional brane slamming into a 4-dimensional matter universe was presented by Princeton astrophysicist, Paul Steinhardt. He worked out the mathematical details over the last year and a half with Princeton graduate student, Justin Khoury; Cambridge, England physicist Neil Turok; and University of Pennsylvania particle physicist and mathematician, Burt Ovrut.
I visited Dr. Ovrut at his Penn Physics Department office this week to talk about this new theory of universe creation from a collision between different dimensions. He began by describing his concept of the 5th dimension.
Now you're talking...
but, it is not simply the 'thrust' or a 'push' developed by the prop against the air that produces the resultant *force* ...)
But yes, that is the same thing. Every action results in an equal and opposite reaction. To say that the propellor pushes against the air is thus mathematically equivalent to saying that the air pushes against the propellor (or the ground against the runner, or the exhaust against the rocket).
One quibble, however: propellor blades do not behave as wings. The pressure difference caused by the difference in camber between the upper and lower surface of the blade is negligible or nonexistent; there is no Bernoulli effect, no aerodynamic lift. The pressure difference arises strictly through angle-of-attack.
Burt's a good guy. He's more than patient with my stupid questions. And he drives a very cool Alfa Romeo.
Is the resultant pressure differential between the front of the propellor and the rear of the propellor due to the blade pushing the air in front backward, displacing it radially, or some of both?
And he drives a very cool Alfa Romeo.
Kewl!
As an overly curious layperson looking for omega=1, it has been my “sense” for a long time that harmonics (or wave phenomenon) must lie at the inception of the physical realm. I was encouraged by the work of this consortium, but their ideas never seemed to get much traction among the peers.
Now, having discovered Burt Ovrut’s ekpyrotic cosmology – and the reaction from his peers - I am ecstatic and very much hopeful the theory will be written in book form for the general public so we can “keep tabs” on it in the years to come.
Sigh ... I wish I were a mouse in your lab.
Indeed, the meaty stuff in the first link is a tough read. And I’m not aware of a good offering (yet) to fully explore ekpyrotic cosmology without all the math. But there is a great book for the general public on the cosmological constant written by Robert P. Kirshner:
The book explores the accelerating universe, dark energy --- and therefore, the cosmological constant necessary to arrive at omega=1.
Maybe you're a little confused.
You're the one saying that there are paid spammers touting drug legalization on FR.
You're the one who has the obligation to identify which screen names they post under and to document those claims. Merely asserting it, as you have done, is not documenting it.
You have not established that they are, in fact, paid spammers. Your obligation includes posting specific information that identifies the spammers and verifies that they are, in fact, paid by the alleged source or sources of money you identified.
Now, cough up the evidence linking these specific posters to the funding source.
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