Arrogance: If I could explain it
to the average person, I wouldn't have been worth the Nobel Prize.
—Richard Phillips Feynman (1918 - 1988) U.S. physicist
(He was awarded a Nobel Prize for his work on quantum electrodynamics)
Big Bang or Big Splat?
(Or, merely IMHO)
By Jack L. Stone, Publisher
(Included in part: excerpt from
Cosmology:
The Shorter Treatment, by Stephen Sparrow
and a treatise by NASA)
INTRODUCTION
ike many of our readers whose inquiring minds want to know, I too share great
curiosity about the wonders of the universe. And, I am a bit timid about discussing this
rather deep topic with the experts in this field as my knowledge is rather shallow. But,
here I dare stick my toe in the water while reminding the reader that one of my favorite
phrases is "to those who don't know anything, everything seems possible." So,
here goes with some observations that do indeed pique my own interests about how things
may work:
IN THE BEGINNING
There persists among the larger personalities of physics a belief in an expanding universe
occasioned by an initial “Big Bang” during which originated all physical
phenomena with which we are presently familiar or are likely to be familiar in the future.
Of course, the most recent research has proven that this idea is merely a subjective
impression, however persistent it may be. As we have recently learned, the limits of the
cosmos are not only finite, but are strictly determinate and fixed. What we hitherto
mistook for expansion is simply a function of the fact that everything within the strict
boundaries of our universe is shrinking. From the largest galaxy to the smallest string,
shrinkage is both universal and uniform (as that term applies over the range of both
quantum and relativistic measure). As a consequence, subjective impressions cannot
distinguish universal shrinkage from universal expansion. The same number of waves fit
within a meter, since both the wavelength and the meter are shrinking together. Particle
interactions do not change, because energies, masses, and all other properties are
diminishing at an exact rate to leave everything in perfect relationship to everything
else.
One consequence of this realization is that we no
longer refer to the “Big Bang” theory of the origins of our finite universe.
There is a finite period between the ignition or triggering of the universe’s
formation that lies beyond actual calculation. Within this period, which we take as brief
but hold open the possibility of something different, the initial assemblage spread from
its origin at the center of the boundaries and spread to the limits, leaving upon the
limits themselves an imprint that many still call the cosmic background radiation. These
residues are like (for the purposes of analogy only) etchings on the surface of a glass
sphere within which everything is shrinking, thus giving the etchings the aura of being
ever farther from us in space and time. During this period of origination, those numbers
that we now call physical constants have little meaning. Once the initial trigger had run
its course, the laws of diminishing returns entered into full play, resulting in all of
the phenomena that we experience today. We may better refer to this conception of
universal origin as the “Big Splat” theory.
MOUNTAIN TO MOLEHILL
Shrinkage may well have a limit, although we have yet to determine what that limit may be.
We know not whether the shrinkage will end in a self-quenching of everything (the more
likely hypothesis) or whether there may be at work yet undiscovered means by which the
process will reverse and renew itself. Since the latter possibility lacks any reasonable
evidence, but lives on hope alone, we may expect that at some future point, the universe
will simply “blink” out of anything we may call existence. It is unlikely that
everything will go at once. Rather, the ending will resemble a vast cascade failure.
Nevertheless, for us, the earliest major disruptions will suffice to make our tiny planet
uninhabitable. Still, we may call this the “Whimper Theory of Universal Ending.”
Many students of diminishing returns, most of whom
have given up the careful and focused thinking required of all shrinking minds and given
way to the desire to go down famously in the annals of history (for so long as it may
last), have undertaken to show that the uniformity of diminution is less than uniform.
Some, for example, claim to have proven that the speed of electro-magnetic radiation is
not a true constant, but rather, that it has either speeded up or slowed down by some
amount, where that amount falls within the error limits of our current measurements. We
must hasten to separate these claims from speculations on the speed of such radiation
during the initial or triggering period, all of which belongs more in the field of natural
philosophy than within cosmology proper. The present claims also separate themselves from
a class of would-be inventors who claim that faster-than-light wave transmission is
feasible, holding out the prospect that we may also and eventually transmit material
objects with the same alacrity. However we might classify the variety of claims and the
erstwhile jargon that purports to prove them, they all lack the vital component that
informs the general theory of shrinkage, namely, physical evidence.
WITHSTANDING THE TEST OF TIME
In this regard, we are reminded that an adequate theory requires more than a memorable
name. Following the appearance of Einstein’s papers on the Theory of Relativity, the
reading public was treated to a veritable barrage of volumes purporting to show that
everything from physics to social and psychological behavior was relative. The
theory’s name had become simply a foundation for a litany; one that the unschooled
took so seriously that it even infected academics. For example, the venerable Mannheim
spent hundreds of pages trying to replace the term “relativism” with the term
“relationism,” as if that maneuver were the proper corrective. One can only
wonder what might have been the pseudo-intellectual barrage had Einstein chosen a
different term by which to reference his efforts. In effect, he replaced the presumed
constant spatio-temporal framework of classical (pre-Einstein) physics with a simpler
constant, the speed of electro-magnetic radiation. What might we have seen had the term of
reference for his work been something akin to a theory of a singular constant?
Albert Einstein
In 1905 German-born American physicist Albert Einstein published his first paper outlining
the theory of relativity. It was ignored by most of the scientific community. In 1916 he
published his second major paper on relativity, which altered mankind's fundamental
concepts of space and time.
Of course, present cosmology has found a proper place
for Einstein’s constant within the framework of general and uniform shrinkage. One
unfortunate consequence of this work is that it reinforces the ban on serious dreams of
interstellar communication and travel without the requisite time-of-transit delays. Even
as our time grows shorter, we have yet to find a usable technique for setting it aside
altogether—at least not until the final Whimper.
(Editor’s Note: Sparrow’s treatment of cosmology goes on to treat the
mathematics, physics, chemistry, and even the psychology and sociology of diminishing
returns.)
ACCORDING TO NASA
The Big Bang model of cosmology rests on two key ideas that date back to the
early 20th century: General Relativity and the Cosmological Principle. By assuming that
the matter in the universe is distributed uniformly on the largest scales, one can use
General Relativity to compute the corresponding gravitational effects of that matter.
Since gravity is a property of space-time in General Relativity, this is equivalent to
computing the dynamics of space-time itself. The story unfolds as follows:
Given the assumption that the matter in the universe is homogeneous and isotropic (The
Cosmological Principle) it can be shown that the corresponding distortion of space-time
(due to the gravitational effects of this matter) can only have one of three forms, as
shown schematically in the picture at left. It can be "positively" curved like
the surface of a ball and finite in extent; it can be "negatively" curved like a
saddle and infinite in extent; or it can be "flat" and infinite in extent - our
"ordinary" conception of space. A key limitation of the picture shown here is
that we can only portray the curvature of a 2-dimensional plane of an actual 3-dimensional
space! Note that in a closed universe you could start a journey off in one direction and,
if allowed enough time, ultimately return to your starting point; in an infinite universe,
you would never return.
Before we discuss which of these three pictures describe our universe (if any) we must
make a few disclaimers:
- Because the universe has a finite age (~13.7 billion
years) we can only see a finite distance out into space: ~13.7 billion light years. This
is our so-called horizon. The Big Bang Model does not attempt to describe that region of
space significantly beyond our horizon - space-time could well be quite different out
there.
- It is possible that the universe has a more
complicated global topology than that which is portrayed here, while still having the same
local curvature. For example it could have the shape of a torus (doughnut). There may be
some ways to test this idea, but most of the following discussion is unaffected.
Matter plays a central role in cosmology. It turns
out that the average density of matter uniquely determines the geometry of the universe
(up to the limitations noted above). If the density of matter is less than the so-called
critical density, the universe is open and infinite. If the density is greater than the
critical density the universe is closed and finite. If the density just equals the
critical density, the universe is flat, but still presumably infinite. The value of the
critical density is very small: it corresponds to roughly 6 hydrogen atoms per cubic
meter, an astonishingly good vacuum by terrestrial standards! One of the key scientific
questions in cosmology today is: what is the average density of matter in our universe?
While the answer is not yet known for certain, it appears to be tantalizingly close to the
critical density.
Given a law of gravity and an assumption about how the matter is distributed, the next
step is to work out the dynamics of the universe - how space and the matter in it evolves
with time. The details depend on some further information about the matter in the
universe, namely its density (mass per unit volume) and its pressure (force it exerts per
unit area), but the generic picture that emerges is that the universe started from a very
small volume, an event later dubbed the Big Bang, with an initial expansion rate. For the
most part this rate of expansion has been slowing down (decelerating) ever since due to
the gravitational pull of the matter on itself. A key question for the fate of the
universe is whether or not the pull of gravity is strong enough to ultimately reverse the
expansion and cause the universe to collapse back on itself. In fact, recent observations
have raised the possibility that the expansion of the universe might in fact be speeding
up (accelerating), raising the possibility that the evolution of the universe is now
dominated by a bizarre form of matter which has a negative pressure.
Possible scenarios for the
expansion (and possibly contraction) of the universe: the bottom orange
curve represents a closed, high density universe which expands for several billion years,
then ultimately turns around and collapses under its own weight. The green
curve represents a flat, critical density universe in which the expansion rate continually
slows down (the curves becomes ever more horizontal). The blue
curve shows an open, low density universe whose expansion is also slowing down, but not as
much as the previous two because the pull of gravity is not as strong. The top (red) curve shows a universe in which a large fraction of the matter is
in a form dubbed "dark energy" which is causing the expansion of the universe to
speed up (accelerate). There is growing evidence that our universe is following the red
curve.
|
We should avoid the following common misconceptions
about the Big Bang and expansion:
The Big Bang did not occur at a single point in
space as an "explosion." It is better thought of as the simultaneous appearance
of space everywhere in the universe. That region of space that is within our present
horizon was indeed no bigger than a point in the past. Nevertheless, if all of space both
inside and outside our horizon is infinite now, it was born infinite. If it is closed and
finite, then it was born with zero volume and grew from that. In neither case is there a
"center of expansion" - a point from which the universe is expanding away from.
In the ball analogy, the radius of the ball grows as the universe expands, but all points
on the surface of the ball (the universe) recede from each other in an identical fashion.
The interior of the ball should not be regarded as part of the universe in this analogy.
By definition, the universe encompasses all of
space and time as we know it, so it is beyond the realm of the Big Bang model to postulate
what the universe is expanding into. In either the open or closed universe, the only
"edge" to space-time occurs at the Big Bang (and perhaps its counterpart the Big
Crunch), so it is not logically necessary (or sensible) to consider this question.
It is beyond the realm of the Big Bang Model to say
what gave rise to the Big Bang. There are a number of speculative theories about this
topic, but none of them make realistically testable predictions as of yet.
To this point, the only assumption we have made
about the universe is that its matter is distributed homogeneously and isotropically on
large scales. There are a number of free parameters in this family of Big Bang models that
must be fixed by observations of our universe. The most important ones are: the geometry
of the universe (open, flat or closed); the present expansion rate (the Hubble constant);
the overall course of expansion, past and future, which is determined by the fractional
density of the different types of matter in the universe. Note that the present age of the
universe follows from the expansion history and present expansion rate.
As noted above, the geometry and evolution of the universe are determined by the
fractional contribution of various types of matter. Since both energy density and pressure
contribute to the strength of gravity in General Relativity, cosmologists classify types
of matter by its "equation of state" the relationship between its pressure and
energy density. The basic classification scheme is:
- Radiation: composed of massless or nearly massless
particles that move at the speed of light. Known examples include photons (light) and
neutrinos. This form of matter is characterized by having a large positive pressure.
- Baryonic matter: this is "ordinary
matter" composed primarily of protons, neutrons and electrons. This form of matter
has essentially no pressure of cosmological importance.
- Dark matter: this generally refers to
"exotic" non-baryonic matter that interacts only weakly with ordinary matter.
While no such matter has ever been directly observed in the laboratory, its existence has
long been suspected for reasons discussed in a subsequent page. This form of matter also
has no cosmologically significant pressure.
- Dark energy: this is a truly bizarre form of
matter, or perhaps a property of the vacuum itself, that is characterized by a large,
negative pressure. This is the only form of matter that can cause the expansion of the
universe to accelerate, or speed up.
One of the central challenges in cosmology today is to determine
the relative and total densities (energy per unit volume) in each of these forms of
matter, since this is essential to understanding the evolution and ultimate fate of our
universe.
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IN THIS ISSUE
We again include many fine articles by our great writing team from around the
globe. Now, allow me to introduce this month's line-up of content:
OUR MONTHLY COLUMNS (plus this one you
are reading by yours truly):
- From the Shack By L. B. Cebik, W4RNL
Some Things I'd Like to See in NEC-5
Unless you work directly with either of the NEC cores (-2 or -4), you may not realize just
how many of the functions upon which you rely are simply not there. Instead, those who
privately or commercial provide NEC with input and output modules embellish the core's
calculations. As a result, the average user is rarely sure of what NEC is doing and what
the implementing software additions are doing. For example, EZNEC and NEC-Win Plus provide
the user with tabular entry screens for entering the wires that make up the antenna
structure, thereby obscuring the fact that the NEC core responds to ASCII inputs, like the
sample lines in this article. Based on Fortran, NEC requires an input sequence that
follows Fortran rules, although between NEC-2 and NEC-4, the number of floating decimal
places allowed on a Fortran line increased.
NEC-2 emerged in the early 1980s, and NEC-4 followed in the early 1990s. However, the
early 2000s saw no further development of the cores. So perhaps it is useful to think
about what one might wish to see in the core of the future, a core that I shall call
NEC-5. My list of druthers is idiosyncratic, based on my experiences with using the cores,
as well as on a good bit of beta testing and technical support. But the simple fact that I
do not catch bugs that others have found obvious is reason enough to consider my list of
desires personal rather than perfectly general.
- Antenna Modeling By L. B. Cebik, W4RNL
S-N, RCA, and MININEC Grounds
We have in past episodes discussed the ground calculation systems associated with the most
common antenna modeling cores, MININEC and NEC. A development in one of the commercial
MININEC packages (Antenna Model) brings those ground calculation systems back into focus.
The MININEC ground calculation system is perhaps the most rudimentary, since its
development paralleled the original intent of MININEC: to offer reasonably accurate
round-wire antenna modeling in a Basic package that would run on early PCs with very
limited RAM and disk storage. Over the years, the latest public domain version of MININEC
(3.13) has undergone various degrees of modification to achieve two major goals. One aim
of redevelopment was to extend the 128-segment and later 256-segment limit for models.
Conversion of the package to a Windows format and a compatible programming code system has
yielded MININEC versions with almost unlimited segments, although almost all such packages
make their core runs more slowly than the compiled FORTRAN that is common to most NEC
packages. The second goal was to correct some of the modeling weaknesses that included an
error that increased with frequency, problems with very close-spaced wires, and potential
errors associated with angular structures. Various software packages have addressed
individual limitations, but Antenna Model has achieved the most thorough set of
correctives.
- Propagation By
Marcel H. de Canck, ON5AU
Propagation Prediction Programs Explained - Part 20
Numerous readers email Marcel frequently with various questions concerning prediction
programs, such as: “What is the meaning of certain input Parameters”, “What
impact, good or wrong, has these inputs to the computed output results”, “ How
to interpret correctly the various output parameters and/or results”. Many among
those readers had questions about “How to use correctly the program VOACAP and
VOA-AREA“. This series is planned as a Tutorial and Guide to use the VOACAP packet
and a detailed Glossary to the various input and output parameters and terms, also used in
various propagation prediction programs. This part 20 wraps up this extensive series.
FEATURE ARTICLES IN THE LIBRARY:
Long-Wire
Antennas
Part 1: Center-Fed & End-Fed Unterminated Long-Wire Antennas
By L.B. Cebik, W4RNL |
 Among the oldest directional antennas are the ones labeled
"long-wire" antennas. Dating to the late 1920s and early 1930s, we still find
some of these antennas in active use--not only in amateur circles, but as well in
government and military service. Classic names, such as Beverage and Bruce attach to early
developments of long-wire antennas. In the group, we include bi-directional antennas such
as the long center-fed doublet and end-fed wire, along with more directional arrays such
as the terminated long-wire, the terminated V-beam, and the rhombic.
The theory of long-wire antennas appears early on in most college antenna texts. Once
noted, along with the obligatory collection of basic equations that describe some
long-wire properties, most authors pass on, never to touch the long-wire group again.
Amateurs come upon one or more representatives of the group and wonder what they do and
how they do it. Few have access to the seminal articles out of which long-wire technology
arose or even to classic books in the field, such as Harper's Rhombic Antenna Design or
Walter's Traveling Wave Antennas. Today, some of the terminology surrounding long-wire
antennas seems strange. For example, how long is a long-wire antenna? Some folks see a
135' doublet (or even a 135' end-fed wire) and think of it as a long-wire antenna. On 80
meters, where the wire is about 1/2-wavelength, it is not a long-wire. However, on 10
meters, the wire is 4 wavelengths and is entering into the realm of long-wire aerials.
There is no definite boundary that marks the entry point to long-wire antennas. However,
when we examine the properties of long wires to see what performance properties that we
want to derive from them, then we shall quickly learn that "long-wire" means for
practical purposes "many wavelengths long." |
Stepping
into a SteppIR
Part 2
By Tom Cox, KT9OM |
 In the first installment of this series, I told you a bit about the SteppIR
Yagi I bought and had begun assembling. It was already obvious, even at the earliest
stages of assembly, that this was not "your father’s (or, Uncle Elmer’s)
Yagi." For one thing, this Yagi claims to cover all frequencies from 20 Meters
through 6 meters, all the while working as well as a three-element Yagi designed for any
frequency in that range. How does it do that? Each element-half consists of a roll of
copper-alloy tape. When fully retracted, the tapes sit on reels in Fiberglas housings
(Element Housing Units, EHUs) mounted on the boom.
On command from the SteppIR’s control box, located at the operating position, stepper
motors in the EHUs extend the element tapes by unrolling them from the reels out into
hollow, Fiberglas tubes (Element Support Units, ESUs), that run perpendicular to the boom,
as conventional Yagi elements would. For any frequency in the design operating range,
there is a combination of element lengths that will cause the SteppIR to perform as if it
were a fixed-element Yagi, designed for that frequency. This all happens automatically,
because the SteppIR control unit is, itself, controlled by its own, on-board
microprocessor, which has recourse to factory-programmed and custom memories of every
needed combination of lengths. It also has a serial interface that allows it to
communicate with most modern transceivers, taking the operating frequency information from
them, and setting the elements accordingly.
When the SteppIR first came out, I was quite skeptical, not being a fan of complicated
antennas with moving parts that have to be trusted at the top of my 120-foot tower.
However, the various SteppIR products (verticals, dipoles, and two-through-five-element
beams) have been on the market and in use for several years, now, and they have garnered a
lot of praise and loyalty from an expanding group of users. I decided to take the plunge.
Won't you join me on this interesting saga? |
The
Popular 80-10 Meter Dipole
with 600-Ohm Transmission Line
By Fred M. Griffee, N4FG (EE Retired) |
 I decided to take a look at a 80-meter dipole but with 600-Ohm transmission
line and see how it would work for all-band applications. In this project, I analyze the
antenna and include the 160-meter band even though the antenna is designed to resonate at
approximately 3.7500 MHz. The height will be set at a mere 35 feet above earth ground, and
the transmission line length will be 50 feet since that is the distance from the antenna
apex to the shack impedance matching network. It will be interesting to compare the
results of a 70 foot height with a mere 35 foot height above ground. Instead of using AWG
#12 copper stranded wire, I use #16 since that is what the advertised W7FG 80-10 meter
dipole with integral 600-Ohm transmission line uses.
The W7FG 80-10 meter antenna I purchased for this included 100 feet of 600-Ohm
transmission line. I wondered whether the transmission line actually had a surge impedance
of 600 Ohms. To analyze this with regard to available equations, I shall demonstrate that
it is within at least ten percent of a 600-Ohm value. And the reactance component of the
transmission line surge impedance (characteristic impedance Zo) will again, be shown to be
inconsequential for all practical purposes.
Included is an impedance matching analysis and current magnitude comparisons to determine
whether a balun and unbalanced matching network can be as efficient or how much lower in
efficiency it may be when compared to a balanced network with a one-to-one balun placed at
its input. |
Uniform
Current Dipoles and Loops
Part 2 - Practical Realization
By Robert K. Zimmerman, Member IEEE |
 This
tutorial set of papers discuss radiation from dipoles and loops carrying uniform current.
It is shown that the radiation resistance for such a dipole is linearly dependent on its
length. Then the radiation resistance of a square uniform current loop is calculated and
found to be in agreement with the theory for circular loops put forward by Foster and was
discussed last month in Part 1. The realization of uniform current dipoles and loops is
treated in this article - Part 2 of this series.Uniform current dipoles have never been regarded as practical, real
world antennas in the literature. Uniform current loops, again, have been given brief
descriptions in textbooks, usually in the small loop limit. In this two-part article,
uniform current dipoles and loops are discussed theoretically (last month in Part 1) and
as practically realized here as described in Part 2. The intent of these tutorial articles
is to show there is nothing abstract or non-physical about such antennas and that the
pattern & gain from a uniform current antenna can be enhanced over that of a
sinusoidal distribution antenna. |
The
T-LOOP for Two Meters
By Dave Cuthbert, WX7G |
| Are you
ready for a simple and effective 2-meter antenna project? If you are, then the T-LOOP
might be just what you’re looking for. It offers an omni-directional radiation
pattern, low SWR, and wide bandwidth in one easy-to-build package. And for just $20 in
materials and couple of hours of construction fun you will have a portable 2-meter antenna
that will handily beat the rubber duck sitting atop your handheld.  What
you get:
· Simple to build
· Low cost
· Efficient
· Ground independent
· Wide band
· No balun needed
The idea for the T-LOOP begins with the one-wavelength loop shown in Fig. 1 of the
article. This antenna has a radiation resistance of 140 ohms.
|
VENT PIPE STEALTH ANTENNA
Version One, 146 to 180 MHz
By WA5SWD, Ed Lawrence |
 Stealth
antennas may be the only practical answer to restrictive homeowner association
limitations. Far be it from me to suggest that a person might wish to flaunt certain
unreasonable provisions, but it might be a lot more practical to ask for forgiveness
rather than permission. Suppose the disguise was good enough that the antenna was never
noticed. The chances are good that one could operate a clean transmitter and never be
detected. No complaints, no problems!
This antenna is for the two-meter amateur band but works well past the weather channels at
162 MHz. |
| |
Well, there you have it, folks—thanks for listening and
remember, the reading lamp is always on for you in the reading rooms. If I can be of
further help, I'm just a Stone's Throw! away.-30-
Best reGARDS, Jack L. Stone, Publisher
jack@antennex.com
May 2006 antenneX Online Issue #109
Send mail to webmaster@antennex.com
with questions or comments.
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Last modified:
December 31, 2010
