265 lines
11 KiB
Plaintext
265 lines
11 KiB
Plaintext
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(word processor parameters LM=8, RM=75, TM=2, BM=2)
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Taken from KeelyNet BBS (214) 324-3501
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Sponsored by Vangard Sciences
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PO BOX 1031
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Mesquite, TX 75150
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There are ABSOLUTELY NO RESTRICTIONS
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on duplicating, publishing or distributing the
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files on KeelyNet except where noted!
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October 6, 1991
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ZPE5.ASC
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This file shared with KeelyNet courtesy of Tom Albion.
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Tom operates the THC Online System in Canada at 604-361-4549.
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--------------------------------------------------------------------
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The leftovers of nothing
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NOTHINGS ain't what they used to be. By using his air pump -- one of
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the high points of seventeenth-century technology -- to remove all
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the air from a cavity, Sir Robert Boyle made it clear to restoration
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England what a vacuum was.
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It was what was left when you took everything away: emptiness. In
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the early twentieth century, quantum mechanics made everything more
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complicated.
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A vacuum is still what is left over when everything is taken away;
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but that no longer means that it is emptiness. The non-empty vacuum
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plays a fundamental role in the way physicists think about matter.
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Descendants of Boyle's air pump now produce vacuums that are, to all
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intents and purposes, completely free of matter. But they can never
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be completely free of energy.
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According to quantum theory, it is impossible to remove all the
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energy from any system. As in a tin of sardines, there is always a
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little bit in the corner that you cannot get out.
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The magnitude of this "zero-point energy" is tiny; as far as
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everyday uses go, it can be ignored. Nobody can measure the zero-
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point jiggling of a pendulum caused by the mote of energy remaining
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in the system when nothing else is left.
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But not all such effects are negligible. Electromagnetic fields also
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have zero-point energies. In the vacuum, every electromagnetic mode-
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-that is, every way in which an electromagnetic field could vibrate,
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if there was one there--has its zero-point energy.
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The energy for each mode is tiny, but there are an awful lot of
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modes. Adding them together reveals a vacuum crammed with energy.
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It is surprisingly hard to find evidence of this sea of energy--
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largely because the level of the energy is the lowest that can be
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reached. There is no lower level with which it can be compared.
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Page 1
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Like sea-level for land maps, the vacuum energy is the reference
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point above which all else is measured.
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Zero-point effects do turn up, though, when matter and vacuum
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interact. The first to be recorded was the atomic Lamb shift.
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Atoms are surrounded by electrons which can have various different
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levels of energy. When an electron moves from a higher level to a
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lower one, it emits a burst of light at a particular wavelength: a
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photon. The wavelength can be predicted precisely from theory.
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In some cases, though, the wavelength observed is different from
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that predicted. The difference turns out to be exactly what one
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would expect from the effects of lots of tiny electromagnetic fields
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working on the electrons--the effect of the vacuum field.
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Not only is the wavelength of the photon dependent on vacuum
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effects, so is the fact that it appeared at all. There are two ways
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for an electron to unburden itself of a photon and come down from a
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higher energy level.
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If the electron is hit by a photon of the right wavelength, it will
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be knocked down, and there will be two photons where there was one
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before. That is stimulated emission, the principle behind the laser.
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Alternatively you can wait for the electron to jump down on its own,
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giving up its photon by spontaneous emission. When the vacuum energy
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is taken into account, the distinction between these two breaks
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down.
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Spontaneous emission can be seen as stimulated emission, with the
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zero-point energy of the vacuum providing the stimulation. So the
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emission of light does not depend just on the atom--it depends on
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the way that the atom and the vacuum interact. By changing the
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vacuum, you can change the way the atom emits light.
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A vacuum between two sheets of metal is not the same as one that is
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unconstrained. Some of the modes of the electromagnetic field are
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suppressed--the modes which represent waves in the field that are
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too big to fit into the cavity.
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By changing the size of the cavity, you can lose certain modes.
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Groups of scientists around the world have built cavities that rule
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out certain modes of vacuum energy, and thus stop atoms from
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emitting photons at various wavelengths.
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Using a related technique, they have designed and built cavities
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that enhance the radiation by allowing the atom to "see" more modes
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of the vacuum radiation than it would if there was no cavity.
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The results of such experiments allow scientists to explore
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otherwise inaccessible areas of quantum electrodynamics, the theory
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of electromagnetic fields.
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An intriguing theoretical point about the way that atoms interact
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with vacuum has been made by Dr Hal Puthoff of the Institute for
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Advanced Studies in Austin, Texas.
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For every atom there is an energy level below which the electrons
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Page 2
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cannot sink. Dr Puthoff suggests that this is because, at the low
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energy levels, electrons cannot lose energy any faster than they
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pick it up from a vacuum.
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It is the vacuum energy that buoys them up, stopping them from
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losing all their energy and collapsing into the atomic nucleus.
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That means that the vacuum underpins the stability of every atom--
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and thus of almost all matter in the universe.
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Force from nowhere Vacuum zero-point energies can explain effects on
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a larger scale as well. The vacuum energy exerts a pressure on
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everything. Normally, this pressure has little effect, since it
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comes from all directions at once and almost cancels out.
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But if two atoms are reasonably close to each other, each will
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shield the other from some of the pressure. There will be slightly
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less pressure FROM the direction of the neighbouring atom than there
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is from every other direction--so the atoms will tend to move
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together.
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This is the Van der Waals force. Though it is weak, it is strong
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enough to hold atoms and molecules together in gases and liquids.
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There are other ways to describe Van der Waals forces, in terms of
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the way the electrons jitter around the atoms, but they also depend
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on the vacuum; they just come at it in a different way.
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An analogous force can be measured between parallel metal plates
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which are placed close together--say a few thousandths of a
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millimetre apart.
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Because the distance between the plates limits the wavelengths
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available for the zero-point energy, there are fewer modes available
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in the vacuum between the plates than in the vacuum outside.
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So the pressure from outside is greater, and becomes greater still
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as the plates are pulled together and yet more modes are ruled out.
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This "Casimir effect" may prove an obstacle for people who want to
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build machinery ever smaller, since it will tend to stick surfaces
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together.
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On the other hand, it may be an opportunity. Dr Robert Forward, a
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physicist who is always ready to speculate on the outlandish--from
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antimatter-driven spaceships to life on the surfaces of collapsed
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stars--has suggested a simple, impractical machine that could remove
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energy from the vacuum using the Casimir effect.
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It is farfetched, but getting the Casimir effect to do useful work
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by holding things together is theoretically possible.
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There are further reaches to vacuum energy ideas which are
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controversial, but still intriguing. Over many years, Dr Timothy
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Boyer of the City University of New York has tried to show that many
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of the results of quantum physics can be achieved using none of its
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assumptions, provided that zero-point energy is allowed.
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Dr Puthoff has recently revived an idea mooted by Dr Andrei Sakharov
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Page 3
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in the 1960s that gravity itself can be explained by vacuum effects,
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more or less as a very long-range version of the Van der Waals force
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between atoms and molecules. That goes against the grain of modern
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theory, but some broad-minded colleagues see it as an intriguing
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speculation.
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And there is the question of the other sorts of energy in the
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vacuum. Interest has focused on the residual electromagnetic fields
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because there is a successful theory with which to discuss them. But
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there are other types of field--those associated with the nuclear
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forces--that are less well known.
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The way that quarks are bundled together in nuclei may have to do
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with vacuum pressure. There may still be a lot of mileage for
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physicists in thinking about nothing at all.
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--------------------------------------------------------------------
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Further information on Zero-Point Energy is freely available
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from KeelyNet and listed in the ZPE series.
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--------------------------------------------------------------------
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If you have comments or other information relating to such topics
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as this paper covers, please upload to KeelyNet or send to the
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Vangard Sciences address as listed on the first page.
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Thank you for your consideration, interest and support.
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Jerry W. Decker.........Ron Barker...........Chuck Henderson
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Vangard Sciences/KeelyNet
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--------------------------------------------------------------------
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If we can be of service, you may contact
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Jerry at (214) 324-8741 or Ron at (214) 242-9346
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Page 4
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