The earth is continuously under bombardment by high-energy particles from outer space. These are cosmic rays, mostly protons and electrons, travelling through interstellar space at very high energy. They were discovered and named long before the discovery of cosmic radio waves. These cosmic rays collide with atoms in the atmosphere where, the explode into several particles, which in turn collide developing a cascade of billions of elementary particles creating a cosmic ray shower. Most cosmic rays particles are stopped high in the atmosphere, so ionizing effects on the atmosphere increase with height. It was the hunt for cosmic rays and the particles they generate in the atmosphere of the earth that led to some of the most important discoveries of astronomy.
THE ELECTROMAGNETIC SPECTRUM OF LIGHT (RADIATION)
A foldedchart 1 and Chart 2 of the ELECTROMAGNETIC SPECTRUM accompanies this PART. Astronomy today is a multi-wavelength discipline. Astronomers observe astronomical objects, even the structure of the universe, at wavelengths from RADIO WAVES with the longest wavelengths, at one end of the spectrum, shown on the chart on the left side, to GAMMA RAYS, the shortest wavelengths, at the other end of the spectrum are on the far right of the chart. They provides a tremendous amount of new information on the COSMOS. In your lifetime instruments to detect nearly all of these wavelengths directly or indirectly have been developed. In the middle of the chart is the narrow band of VISIBLE LIGHT, of the entire electromagnetic spectrum only the visible or white light can be seen with the eye. Which means with the naked eye we are seriously handicapped from seeing the vast radiation of the cosmos and the objects that create them. The visible light and objects that generate them, make up about 5 % of the observed contents of the universe. To find out what else is in the universe ways to detect the other types of radiation had to be found. Detecting the other types of radiation allows us to see different processes and different parts of things that exist out there. The radiation that they call RADIO seems to be the limit, but may not be, of the energy emanating from some of the contents of the universe. MICROWAVES, the next radiation just to the right of the RADIO WAVES, along with RADIO WAVES provide the basis for the developing science of RADIO ASTRONOMY, briefly described in this PART 9. In future studies the other radiations and their detecting equipment will be discussed. On the chart notice the comparisons of the wave lengths made to objects in the real world, shown on the bottom of the chart. Note also the size of the wavelengths are given at the top of the charts under their names, so when references are made in texts that mention the wavelength of something, the size will identify the radiation being discussed.
RADIO WAVES are very large, they vary from 104 meters to MIRCRO WAVES that are just 10-2 meters. You are familiar with many of these wavelengths, you call them AM RADIO, or FM RADIO, HIGHFI, OR TV. MICROWAVES are used by the telephone companies for telephones, and MICROWAVE OVENS. You know that ULTRAVIOLET light can burn you, and you are aware of X-rays and their destructive power, but also their utility. GAMMA RAYS take you into the realm of nuclear power and radiation so small that it can destroy matter. The stories of how astronomers learned to detect all of these with space or land bound instruments is extremely fascinating. What they, in combination reveal of the universe is incredibly astonishing. And that is where we are going in these cosmological researches in an effort to try to learn just how GOD does it; how he did it all.
Observations in the INFRARED reveal cool galactic gas and dust; in the ultraviolet, hot young stars. At RADIO WAVELENGTHS, we spot neutral hydrogen gas and its motion as well as synchrotron radiation (electrons moving in a magnetic field at close to the speed of light) in galactic or intergalactic magnetic fields. The new X-ray telescopes detect very hot gas in and between galaxies and optical wavelengths reveal the light from stars and ionized gas clouds. All combine to permit a fuller understanding of all that is contained in the immensity of space. (Nature 24 October 2013 p, 439)
SOME CRITICAL EVENTS
In 1610 Galileo published the first observations of the sky of visible light with the newly invented telescope and the world changed forever. He established the fully three-dimensional universe. As Galileo went on to one momentous discovery after another, he observed that Io, Europa, and Ganymede, moons of Jupiter orbited in a precise 4:2:l resonance. Io orbiting four time for the two orbits that Europa made and the one orbit that Ganymede made. How could this be? It was the French mathematician and astronomer Pierre Simon Laplace who worked out the three body situation now called Laplace resonances. (Bell p. 132) They are found elsewhere in the solar system as well. But it would be more than 340 years later when a new view of the sky would be provided by a new type of telescope, the radio telescope. White light viewing would have to take a back seat now that new drivers and a new vehicle was available.
In 1755 Immanuel Kant would not accept that the Milky Way was the universe. His observations of curious objects he believed to be outside the Milky Way suggested to him that many of them were "island universes" or individual galaxies like our own. He was right, it would take more than one hundred and seventy five years before others would not only believe him, but prove that he was right. (Bell p. 268)
In 1912 Victor Hess (1883-1964), in a classic, perilous flight in a gas filled balloon carrying a charged electroscope, to an altitude of 3 miles finding ionization of the atmosphere increased tenfold. It would take years before the significance of this was appreciated. In 1937 he received a Nobel Prize for his work. From little beginnings great things develop.
It 1917 Vesto Slipher (1874-1969) published his results of spectroscopic observations of spiral galaxies (called nebulae at that time) . Using very long photographic exposure, he measured the wavelengths of absorption spectral lines and found large differences in the wavelength of certain lines as measured in the distant galaxies and in our own Galaxy. In light from an approaching star all wavelengths are shifted towards the blue end of the spectrum, and from a receding star the wavelengths are shifted towards the red. The fractional wavelength shift seen on the primitive spectrograms measured the velocity at a fraction of the velocity of light. Sophistication of the process permits one to observe the motions in spiral galaxies, if shifted towards the blue that part of the disk is moving towards us, if shifted towards the red that part of the galaxy is moving away from us, so the spinning of a galaxies can be determined. The spectral likeness he observed were all shifted towards the red end of the spectrum indicating that entire galaxies were all receding from us with very high velocities. (Graham-Smith pp. 150-151)
In 1918 Harlow Shapley published his model of our Galaxy based on his acute observations of Cepheid variable stars because their intrinsic luminosity helped astronomers calculate distance. They gave him a way of assessing the scale of our Galaxy. He had also noticed NOVAE, bright but short-lived stars, could also be used as distance indicators. As a keen observer with the instruments he had at that time he had also noticed novae in a fuzzy nebula looking object called Andromeda and similar nebulae looked fainter than those in our Galaxy, so they had to be much further away and that they may be in galaxies like our own, but at huge distances. Later he learned he was right. (Graham-Smith pp.149- 150) He was one of the first to try to estimate the size of our galaxy. He was the first to identify where the center of our galaxy was located. He was making great headway. (Bell p. 268; 276) They knew by 1981 that our galaxy exceeded 200,000 light years in diameter. (Bok p. 25) And it may extend even farther.
In 1919 Edwin Powell Hubble (1889-1953) went to work at the Mt. Wilson Observatory with the Hooker Telescope, then the largest telescope in the world. His switch from a legal career to being an astronomer was to change the world.
From 1922 to 1923 Hubble's observations permitted him to concluded that the faint smears of light people saw in the night sky were not clouds of gas, as astronomers then thought, but entire galaxies, and he proved that they were moving away and receding from one another. The farther away galaxies were the faster they were moving, he showed that the universe is expanding at an astonishing rate. Hubble developed an equation that used the speed of light to calculate just how fast the universe is expanding, it is called the Hubble Constant. And to this day they are still debating its value. (Scott p. 22) In 1964, with others, I had visited the Observatory little knowing the impact it would have on my life. Using the new Wilson telescope, Hubble had made one discovery after another and formulated the law recognizing that the apparent velocities of receding universe are proportional to their distances. (Chambers p. 697) It has taken decades to refine that number. It is now one of the critical numbers required for stability in the universe.
In 1926 Hubble published a survey of galaxies classifying them into ellipticals, spirals, and irregulars. Now, highly refined,the classification is still in use. He was looking at galaxies well beyond Andromeda, a large spiral 2.5 million light years from us, and one of our local group. He found the number he could see, white lights, increased as he looked at fainter and fainter galaxies according to a simple law. On a large scale, and averaging over a large number of galaxies, the Universe was seen to be indeed populated uniformly with the same average number of galaxies per unit volume at all distances and in all directions. (Graham-Smith pp. 150-151) But to get the average density of visible matter in the homogeneous universe, an important quantity, new instruments and more observers were required. Hubble's book, IN THE REALM was my favorite for many years. I watched with great anticipation when the great 200 inch telescope was put into operation at the end of the 1940's. I had become a member of the Astronomical Society of the Pacific and was appraised by their publications of all the latest discoveries. Cosmology was getting off at high speed, and today it is like a rocket.
Hubble worked out the average density of visible matter in this homogeneous Universe, a quantity which is of great significance in cosmology. In light from an approaching star the wavelengths are shifted towards the red. The fractional wavelength shift measures the velocity as a fraction of the velocity of light. Some objects were moving away from us at more than 65% of the speed of light. Hubble found that spectral lines were shifted towards the red end of the spectrum, indicating the galaxies were all receding from us with very high velocities. He found that these velocities were proportional to the distances of the galaxies. The redshift-magnitude relation, as it was called, indicated that the whole Universe seemed to be expanding as though everything in it had once been concentrated in a single infinitely dense point. The time scale of this over whelming behavior was deduced from the redshift-magnitude relation to be more than 10 billion years. Now they had an idea of both the size and the age of the Universe, all achieved using information acquired optically from visible light only.
In 1927 Jan Oort (1900-1992) provided the first observational proof of Bertil Lindbladf, who a few years earlier, stated the galaxy was rotating. Unbelievable! Oort confirmed the Milky Way rotates, he also noted that the rotation is differential, stars closer to the center were going faster than stars farther out that lagged in speed. The sun was about half way out and takes about 250 million years to orbit the galaxy's center. (Bell p. 276) How many times has it made the trip?
In 1929 Hubble finally published his discovery of the universal expansion, when he found that the volume of the observable universe was expanding, it meant that everything we could not see was much closer together many years ago. These observations became the main basis of observational cosmology until the early 1950's when radio astronomy unexpectedly entered the scene. (Bell p. 278)
In 1932 Karl Jansky published his investigations into unexplained background noise and atmospherics that were a real bother, that was plaguing Bell Telephone attempts to refine their communication links. Jansky, by using primitive 15 meter antenna to locate the origins of a hissing noise, found it came from outside the earth. He even made a rough plot of the strength of the signal over the whole 360o of the sky. Strangely he noticed that the pattern he detected "moved by about lo every day, slipping by a whole day in the course of a year, showing that it came from a region of sky that was fixed in relation to the stars and entirely outside the Earth and the solar system. The scans showed that the strongest signal came from the center of the Milky Way, the brightest part of our Galaxy, and especially from the constellation Sagittarius, which contains the center of our Galaxy." (Graham-Smith pp. 4-5; Bell p. 282) Sagittarius is low in the southern sky. This was the first observation of radio waves from space. Jansky was actually picking up the signals from the center of our Galaxy where the monster black hole resides. But little notice was taken of it. Only a few picked upon the implications. Then Grote Reber, an ardent radio amateur who had communicated with 60 countries, under his call sign W9GFZ, was getting bored. He read the work of Jansky and set out to conquer the world of radio astronomy.
In 1937 Reber built the first reflector radio telescope 9.5 meters in size with his own hands, all on his own. The 50 foot high object in his back yard was more than a curious object. "After many difficulties, he was able to draw maps of radio emissions from the Milky Way." (Graham-Smith p. 9) Reber had no astronomical education so he attended courses at the University of Chicago. There he interested Otto Struve, the director of Yerkes Observatory. Astronomers were rigid and biased and had great "resistance to the idea that anything other than a photographic plate [from white light] could produce any useful astronomical information." (Graham-Smith p. 11) But the time for change had come.
In 1933 the observations of Fritz Zwiciky who was studying galaxies and clusters of galaxies postulated the need of Dark Matter, ubiquitous unseen material, to explain his findings. (Bell p. 288)
In 1937 Bernard Lovell (1913-2012) had ideas about cosmic ray showers. He went to work with Patrick Blackett (1897-1974) , who was professor of physic at Manchester, England, and they established a new laboratory for high energy particle physics. "Before cosmologists can understand the vastness of the universe, the particles physicists must teach them what the cosmos consists of. " (Seife p. 133) They made proposals on detecting comic ray showers at Jodrell Bank, twenty miles out of Manchester. But both were called into the war effort in 1939. Blackett worked on Operational research, Lovell was working in radar, but together they authored a paper on the possibility of using radar to investigate cosmic ray showers and find the origin of the primary cosmic ray particles for which the Noble Prize was awarded. Lovell went into radar and radio astronomy. Hanes Hey, another radar man, was also working on detection systems. Lovell returned, after the war, to Manchester, borrowed some military equipment to experiment with from Hey, ending up finally back at Jodrell Bank where he began building even larger receiving antenna to check out echoes and cosmic ray showers, starting the sequence of even larger radio telescope which eventually made Jodrell Bank Observatory and Lovell a leader in radio astronomy. (Graham- Smith p. 66-67)
In 1940 Reber published his findings that clearly showed that the origin of 'cosmic static' was associated with the Milky Way. It was kept short at the advice of Struve.
In 1944 Reber published again, but with data more refined from improved receivers, showing that radio waves were very different from the visible stars. He continued to improve his detectors and his best results were published in 1948. In 1954 he was observing at low radio frequencies from the top of Hawaii, then moving to Tasmania where he built the huge antenna system for the long radio wavelengths, an inspired pioneer of radio astronomy.
In 1946 Francis Graham-Smith started his research in the new science of radio astronomy. To him at first "it was not at all obvious that radio would have any substantial contribution to make to our understanding of the Universe on any scale, except perhaps there might be something to be learnt about the Sun from its out bursts of radio emission...there was no conception that radio could contribute to cosmology...it now provides the most fundamental observations of the early Universe and its evolution." (Graham-Smith pp. 2-3)
THE BIG BURST (BIG BANG)
In 1946, Roman Catholic priest, physicist and astronomer Georges Lemaitre (1894-1966), from Belgium, formulated the PRIMEAVAL ATOM HYPOTHESIS, the Basis for the BIG BANG THEORY, which says everything in this 'universe' that ever was or will be-all matter and all energy-was compressed into a tiny point called a "singularity" or "cosmic egg" the size of grain of sand. It was hot and incredibly dense, but it contained all the building blocks of the universe. It erupted in a fiery burst that created space and everything in it-our universe. His hypothesis later became a theory. The burst was the BIG BANG. Scientists, as yet, cannot explain what went on before the burst. (Scott p. 23) The Mormons believe not only was there time before, and space into which this universe could expand into, but there were at least 1056
In 1946 there was a serious problem in science about the origin of heavy elements, even the very origin of the elements, particularly an explanation was needed for the relative abundance of hydrogen and helium, which are the dominant species in the Universe. That will be the subject of a future discussion.
1948, George Gamow (1904-1969), with two associates, Alpher and Bethe, published their ideas that hydrogen and helium and heavy elements were a result of a very dense and very hot early phase of the Universe, looking backward from the Hubble expansion to the concentration indicated. (Graham-Smith pp. 150-151) This was the Alpha-Beta-Gamma, but Bethe only allowed his name to be used for Greek euphony. But it wasn't the answer to it all.
In 1947 Graham-Smith started research with Martin Ryle, at that time they had no idea that radio observations could be developed into the wonderful contributors of spectacular discoveries now being made by radio astronomy. With increasingly sensitive radio receivers, digital computers, and the use of large arrays of interconnected radio telescopes, they get the equivalent of a single telescope of immense size to collect as large a signal as possible. Now they have the ability to detect and manipulate the oscillating electric fields in a radio wave, a technique which is almost impossible for white-light waves. But white light is such a small portion of the electromagnetic spectrum. How could the photons or wave lengths of the "other light" be detected? There were those whose fertile minds were thinking of how they could detect every wavelength of the complete electromagnetic spectrum. And eventually they did.
1949, at a meeting in my home at Ruth, Nevada, Dr. LaMar Anderson, professor of Geophysics at Columbia University, Dr. Angus Blackman, professor of Chemistry at BYU and I met exchanging ideas about the latest announcements by chief scientists that the age of the Universe was at least 2 Billion years. We were amused somewhat because, as Mormons we knew that by the end of the third day of creation when the sun, moon, and earth had been configured, that time that had already elapsed in this part of the creational activity for at least 2.55 billion years. Dr. Anderson was to become well known for his contribution to the study of moon rocks and history predicting the moon rocks would be older than 2.5 minimum in age and likely the maximum age would be a more than 4 billion years. He was right, but did not tell co-workers that his predictions were based on data obtained from an Egyptian ancient record known as the Book of Abraham recovered from Egyptian tombs, translated in part by Joseph Smith, and published in a religious publication known as the Times and Seasons in the fall of 1844. (See Part l, of this series). Anderson was my cousin, and is alive at this writing, and Angus was my best friend living across the road from me. I was on my way to become a geologist and scientist and would eventually teach geology and astronomy at six institutions. But we knew then that science had a way to go. Now just recently the age of the universe, being used for conversational purposes, because they may refine the number is 13.82 billion years, they are getting closer. But it has taken science 170 years to find out what the Mormons knew already.
In 1951 a famous argument developed between the radio astronomer Martin Ryle and the theorist Fred Hole. After the discovery of radio waves from the Sun, there followed the discovery of a large number of unidentified discrete radio sources initially thought to be some sort of stars in our Galaxy. Those discrete sources turned out to be outside the galaxy, much farther away from Hubble's spiral galaxies, at distances that were very interesting in cosmology. They also identified the radio galaxy Cygnus A, discussed in earlier parts of this series, the large red shift of this galaxy and of others discovered soon afterward, showed that most of the hundred or so radio sources were all at great distances, outside our Galaxy, and at distances significant to cosmologists. suddenly, cosmology mattered a great deal, So did radio astronomy. There were astronomers and there were theorists. The revolutionary work of Albert Einstein on the structure and evolution of the universe was in the domain of theorists, and outside the radio world. Cosmology was not the business of radio astronomy, or so it was thought. How things do change. Ryle went on to identify more than 2000 radio sources along with many very faint ones. What an immense task at that time. The results meant that the population of radio galaxies was greater in the more distant parts of the universe than locally, diametrically opposed to existing theories. Discoveries continued, sophistication continued, now there are more than one million known extragalactic radio sources, seemingly evenly distributed over the sky and indicated there were many more faint sources many orders of magnitude fainter than those Ryle had found. What are they? Now vast distances almost back into the few hundred million year after the BB, are being subject to careful scrutiny, and becoming overwhelmingly important at the large distances now being reached by sensitive surveys. (Graham-Smith pp. 154-155) With the new equipment, some of which have been mentioned, and more will be, they are now exploring the universe on a grand scale, and working out the details of the strange geometry of our finite Universe.
In 1952 Galbraith and Jelley, with the Atomic Energy Research Establishment, showed that electrons in the shower radiate a detectable flash of blue light now called Cerenkov radiation after Pavel Cerenkov who first characterized the radiation. Charged electrons travel at nearly the velocity of light through the atmosphere, in which light and radio travel appreciably more slowly and radiate the blue glow of light. Cerenkov got the noble prize for this work in 1958. (Ibid p. 67). John Jelly pointed out that there should also be a pulse of radio that could be detected. He came to Jodrell Bank in 1964, bringing particle detectors which would respond to cosmic ray showers where they developed a sensitive receiver and a small upward looking radio telescope. Detectors were set up and they were the first to detect radio waves from cosmic showers. (Ibid p. 68)
By 1957 they had established the Lovell Radio Telescope at Jodrell Bank, 20 miles south of Manchester, England which was gradually expanded to a 350 foot radio telescope contributing a great deal to early radio astronomy. By the end of the sixties Jodrell Bank was becoming exclusively radio astronomy and had left searching for cosmic showers. With advancements in the science by 2002 the old 250- foot telescope had been a pioneer in the search for radio pulsars, gravitational lenses, extraterrestrial intelligence, and much, much more. It was rusting after nearly four decades of abandonment when it was given a major face lift making it 30 times more sensitive than at its debut in 1957 and again impressed astronomers with its discoveries. (Astronomy p. 28, May 2002)
In 1957 there were massive organizational accomplishments, military and communications driven. THE DEFENSE ADVANCED RESEARCH PROJECTS AGENCY (DARPA) was formed to oversee space-related technology. The JET PROPULSION LABORATORY (JPL) advanced the EXPLORER MISSIONS, and the DEEP SPACE NETWORK (DSN) was established with large radio telescopes spaced roughly equally around the world under the control of NASA. These included California, Madrid, Spain, Canberra, Australia, each with one large 230 feet and several smaller, 112 feet, radio telescopes. Eventually more than 90 active missions were operated by NASA and other international space agencies. (Bell p. 306) Things were beginning to get really big.
In 1963 the Pierre Auger Cosmic Ray Observatory, named after the man who had found many cosmic showers, was set up in Chile. It Consisted of 1600 detectors spread over an area of more than 3000 square kilometers. Ultra violet light, also generated by the showers, was also detected. The observatory was also designed to detect the very highest energies which arrive on Earth at the low rate of l per square kilometer per year. (Graham-Smith p. 68) Air showers are also generated by energetic gamma-rays which are photons from radiation at the end of the electromagnetic spectrum from radio waves. Two observatories have just become operational known as HIGH ENERGY STEREOSOCPIC SYSTEMS (HESS) AND MAGIC at the INSTITUTO ASTROGROFISICA DE CANARIAS on the island of La Palma. GAMA RAYS are of particular interest in research for the sources of high-energy radiation, since that radiation travels directly from the source to the observer without deviation by the large-scale magnetic field of our Galaxy.
In 1982 the combined results of three radio telescope, on two Hemispheres, of further sophistication, resulted in a cosmic wave map of the whole of the Milky Way, providing a spectacular view of the Milky Way revealing many features which are invisible to optical [white light] telescopes. "This is one of the clearest views we have of our Galaxy." (Graham-Smith p. 12) White light telescope have a lot of difficulty in viewing galaxies because of the clouds and trails of dust that obscure white light, but dust clouds are no barrier to radio waves. As it was later to be found, all galaxies have radio wave sources, and there is much more besides that.
RETURN TO JODRELL BANK AND SUPERNOVAE TYPE Ia
Back at Jodrell Bank, Lovell continued to build larger telescopes, the next was his 66.4 meter parabolic reflector. And, as it often happens, when a powerful new scientific instrument is finished the most exciting results are a surprise. They examined the other larger member of our local group of galaxies, Andromeda, their historic map was published in 1950. They found that Andromeda generates radio waves with about the same strength as the whole of the Milky Way. They detected the spiral structure of Andromeda, that distant galaxy, and found immense gas between stars in the spiral arms. Radio Astronomy was now on its way to its cosmological destiny.
It became obvious that for great distances they needed some sort of object that could be detected at great distances where its apparent luminosity could be compared with the same type of object at small distances. Such an object was hard to find, but finally they found that a particular type of Supernova, Supernova Type la, whose brightness and origin suggested that nearly identical objects could be observed at great distances. But at such large distances they would be very faint, and could only be found by using a large telescope dedicated to searching for such newly bright objects whose sudden brightness sometimes would last for only a few weeks.
The 4 meter optical telescope at CERRO TOLOLO located in the ideal observing conditions of the Atacama Desert and operated by the INTER-AMERICAN OBSERVATOR, became the main source of newly discovered Type Ia supernovae, such as SUPERNOVAE 1993 J (supernovae are identified by the year they are found, in this case 1993, and member rank , J, of others.) (Arnett p. 451) Each discovery needed to be followed-up on by large telescopes, and groups of astronomers all over the world became involved in detailed observations of the spectra and brightness profiles of dozens of faint supernovae. The dramatic results was the discovery of cosmic acceleration. Two papers announced the discovery. They were by two different groups working independently, one by Saul Perlmutter with 32 co-authors and the other was by Brian Schmidt, with 23 co-authors. Since they verified each other, a Noble Prize was split between Perlummter and Schmidt whose main collaborator was Adam Reiss, often quoted in these series.
As acceleration was studied observations began to fine tune the detail. The intrinsic brightness of the Standard Candle turns out to be consistent to within 15 %. As comparisons were made between nearby supernovae, and distance ones, it was determined that the distant supernovae were 10-25 % further away than expected. The universe kept getting larger and older. And it was clear that the rate of expansion of the universe was accelerating, and expansion seemed as though it would never stop. Gravity would never pull all the matter back, matter would not get tired and quit expanding, it would continue on gradually becoming radiation. Within 100 Billion years little would be left but radiation which would be equal to the energy that was present in all the matter that once occupied the universe. Mormon ideas suggest that energy gets reprocessed and worlds without end can be created out of matter unorganized. The Universe by this analysis is flat, it does not topologically curve back on itself or take on weird shapes and forms. It puts a limit on theories. (Graham-Smith p. 163)
THE COMPOSITION OF SPACE
There was in an equation gradually emerging from efforts of Hubble and Einstein, a "constant." It is fact called the "Cosmological Constant." It is expressed as "dark energy." This is supposed to pervade all of space, and acts as a universal force in the opposite direction to gravity. This dark energy is another component of the local matter-plus-energy density of the smoothed out universe. It determines the effect of gravity on the expansion of the universe, it constitutes no less than 72 % of the averaged-out density of the universe. Only about 5 % of the matter-plus-energy density of the smoothed out universe is actual ordinary massive matter, known as 'Baryons.' That leaves 23 % for a third component creating gravity, which in the discussions of galaxies in earlier entries to this series, is "dark matter." We are learning more about it and becoming more familiar with as telescopes probe the limits of space. But its nature and distribution are both only recently becoming partially known, so some things are beginning to accumulate as the penetrating observations of the universe continue. (Graham-Smith p. 163) Great discoveries for cosmologists lay ahead.
But we are left wondering why space is so exactly flat, when the proportions within matter-plus-energy seem to conspire to give a total gravitational effect exactly counter balancing the constant for expansion.
In 1981, Alan Guth proposed that at an early stage in the universe in the expansion of the universe, when instead of the regular inner expansion which we observe today, there was an enormous exponential growth over a very short time scale, now known as the 'inflationary model,' Any curvature of space is removed, and it accounts for the uniformity of the universe on the largest scale. Going into 2014, how inflation actually occurred, is still a matter for speculation. The concept is generally accepted as the only explanation of the flatness of the present Universe. But the event itself cannot possibly be observed; it took place in a time many orders of magnitude less than one second after the creation itself, while efforts to observe radiation refer to a time 370,000 years afterwards. Observations were then made that became the next contribution of radio astronomy to these overwhelming important questions about our Universe. For example the average density of the universe is very low; most of the Universe is very nearly a pure vacuum, and spreading the visible material of the galaxy over the whole of space gives a density corresponding to only a few hydrogen atoms per cubic meter. A single hydrogen atom created every year in a volume of several cubic kilometers would be sufficient to replace the galaxies as they disappeared into the remote distance. (Graham-Smith p. 153) Except, hydrogen atoms are not being produced by any circumstance in the Universe today. All the hydrogen in the universe will last only as long as it takes to fuse hydrogen into helium. A long, long time.
Until recently it seemed an impossible dream that we would ever actually see and understand anything that happened in the primitive universe. But radio astronomy has achieved exactly that. (Graham-Smith p. 165) The Hubble Space Telescope has allowed astronomers to determine that the a galaxy appears to gain speed and move away at a rate of 50 miles per second for every 3.2 light-years it is away from earth, and the farther away from earth it is, the faster it moves. So they now believe the universe of this particularly BURST is around 13.82 billion years. (Scott p. 27) That could mean that the diameter of the BURST has by now exceeded 50 billion light years. Compared with a 24 hour day, the Earth would not have been assembled from the heavy elements produced by generations of supernovae la, providing the heavy elements from which earths are formed, until the late afternoon, and humans would have existed for only a second or two. And the first born, the first actual man, nutured in a pre-spirit world- the first father, Adam, only appeared on the scene less than 6000 years ago. (Abraham l:3)
THE LAST SCATTER SURFACE INSIDE THE BURST
It has been shown that helium was present universally, with an abundance of 25 % compared with hydrogen, exactly the proportion expected in the synthesis of elements from elementary particles in a very hot, dense, fireball. They predicted that the fireball would itself be observable, not in its earliest stages, but after expansion. In its earliest days and years it cannot be seen at all, we are limited to observing a surface beyond which no telescope can penetrate. This is a boundary between hot, ionized gas, which cannot be penetrated by radiation and the later, cooler universe in which ions (particles with a charge) and electrons combined and light and radio can propagate. This boundary is known as the LAST SCATTER SURFACE, or COSMIC PHOTOSPHERE (Graham-Smith p. 166) This stage of the earliest beginnings and history of the BIG BANG, is the furthest we can hope to penetrate with any of the modern telescopes. The energy ball, or PLASMA, at that stage is still hot from the original fireball, but it cooled to about the same temperature as some hot stars and gas clouds in our Galaxy, about 4,0000 Kelvin. This final barrier to a view of the BIG BANG is at a very large distance, (at least 25 billion light years) so it is in a region of the universe which is not only very young, but is seen at a very large redshift. Present telescopes can pick up the faint light from galaxies with redshifts 'z' up to 10; the redshift at the last scattering surface however would be about z =1500. Such a huge shift changes the radiation from white light at a wavelength of around l micron to short wavelength radio, at around l millimeter wavelengths. One of the reasons for building submillimeter telescopes. The radiation from the last scattering surface is everywhere, the radiation from this cooling stage of the Big Bang is seen all around us. Herein lies the most important contribution of radio astronomy to the understanding of our Universe.
THE TROUBLESOME NOISE IN THE SKY
In 1961 Bell Telephone was measuring radio background to explore the limitations on long distance radio communications. Shorter wavelengths were desired. They could eliminate noise coming from the Galaxy. But there was also some noise they could not account for. Edward Ohm set out to detect just how low the background was. He set up an antenna 20 feet in diameter. The lowest signal Ohm could find was a background noise corresponding to a temperature of 22 Kelvin (degrees absolute) with some unknown noise . Two radio astronomers, Arnold Penzias and Robert Wilson, joined Bell and installed a new receiver with unprecedented sensitivity and low interfering internal noise. They set out to find the origin of the background noise picked by Ohm, even thinking it might be dirt on their antenna, or bird droppings, so they cleaned up their telescope, but they picked up a small signal of around 3.3 K, which came from everywhere in the sky. By pushing the accuracy of their measurement to the limit they had stumbled upon the first detection of the COSMIC MICROWAVE BACKROUND. Unknown to each other, there were two other groups working on the same problems, an unexplained radiation noise.
At nearby Princeton, Robert Dicke, was building a receiver and antenna deliberately to look for the remnant radiation from the Big Bang, expecting to find a signal of about 3 Kelvin. At MIT, another party, Bernard Burke, who knew what was going on at Bell and at Princeton, acted as a go between both groups connecting their ideas and observations to the Bell laboratory which permitted the Bell group to announce the discovery of the COSMIC MICROWAVE BACKGROUND, (CMB) The CMB is the thermal radiation from the cosmic photosphere which before the very large redshift would appear to have a temperature of about 4,000 K, about that of a hot star like our Sun, spanning the visible wavelengths as a smooth spectrum. During the red shift from the early universe to the present day the spectrum would be transformed into radio microwaves and very long wavelength infrared rather than the much shorter wavelengths of white light. Now they had to measure the temperature of the spectrum to prove the origin of the radio background, but to do so they would have their detectors completely isolated from the terrestrial sources of the earth with its variety of radio noises.
In 1989 they launched the satellite COBE, discussed in earlier parts of this series. It was carried into orbit to an altitude of 900 kilometers (540 miles) above the earth, with a scanning radiometer. (FIRAS) This measured the infrared temperature over a wide range of millimeter wavelengths, with spectacular accuracy. The CMB temperature is 2.728 plus or minus .002 K, measured over the wavelength range of 1-10 millimeters. But they needed a standard for comparison, "so COBE had a large vacuum flask with liquid helium ...with a known temperature. The liquid slowly boiled away, thus limited the life of FIRAS to ten months. During this life time the satellite slowly rotated giving repeated scans of the whole sky which averaged out to give an ever-increasing accuracy. The faint whisper of the Big Bang had been pinned down, the origin of the troublesome noise had been identified and cosmology had entered a new era in which it has become an exact science." (Graham-Smith p. 170)
A scientific paper was announced with 23 authors, the lead author was John Mather, the COBE Project Scientist, he was credited with the outstanding accuracy achieved in this NASA mission.
At the same time there was a small group of rocket scientists in Canada who had designed a similar receiver and launched it within a few weeks of COBE. If they had been just a few months earlier they would be celebrating the first to measure the cosmic background spectrum by Paul Gush. Their temperature determination was 2.736 K. Not quite as accurate as Mather's result, but close enough to corroborate the discovery.
The CMB as measured by FIRAS is uniform over the whole sky. As the primeval gas or plasma expanded it had cooled. At some time there would have developed structure, tiny differences in temperature, which evolved into the universe as we now know it. Another instrument was on the COBE, satellite, the DIFFERENTIAL MICROWAVE RADIOMETER. (DIRBE) It was the first to show that the CMB was not perfectly smooth, even though the differences were extremely tiny, very faint indeed, only about one part in 100,000 of the 3o radiation. But never- the- less there was a minute pattern within the radio signal that is itself one of the weakest ever to be detected. But it was done by DIRBE. For this achievement George Smoot shared the 2006 Noble Prize with Mather. Now what was needed was a map with better angular resolution. (Graham-Smith p. 171) So, they said, let's go map it.
BOOMERANG, first deployed in 1999; derived from BALLOON OBSERVATIONS OF MILLIMETRIC EXRTRAGALACTIC RADIATION AND GEOPHYSICS, provided the first highly detailed measurement of the background radiation. It was re-fited in 2003 to make it more sensitive to polarization. It revolutionized the field of CMB astronomy . (Seife p. 241) It was a balloon lofted to about 24 miles with a set of microwave radio receivers which made a long series of repeated scans of the CMB. It was flown almost over the South Pole in a circulating air current of cold polar air which returned the Balloon like a Boomerang to the launching base after 10 days of continuous operation. The results provided the first detailed picture of the structure in the CMB. There were 36 scientists sharing in the discovery for they obtained a map showing the CMB did have a mottled structure with a pattern around lo across. (Graham-Smith p. 171) In time those small patterns or structure became stars, star clusters, then galaxies, and so forth.
Our galaxy as well as all other objects in the universe have their own individual velocities quite apart from the expansion of the Universe. The velocity of our galaxy is only about one-thousandth of the speed of light so our galaxy is moving through the universe at a velocity of 370 kilometers per second. But this is purely local velocity, shared by galaxies in our local group and is not in any way related to the overall expansion. This pattern has to be removed from all observed maps of the CMB as the first step in analysis so they can measure velocities in relation to the universe as a whole.
The easily observable spectrum of the CMB stretches from around a wavelength of 25 millimeters to 0.3 of a millimeters; extending to the shortest wavelengths accessible by radio techniques, in fact the classic spectrum obtained by COBE used techniques which are best described as far infrared. The difference is that the infrared receivers use bolometers, which absorb and measure energy giving measurements of intensity. Radio techniques deal with the voltage waveform of the incoming signal preserving both the amplitude and phase. Both techniques were used in COBE, where the first indications of structure were obtained by radio receivers. The next and most dramatic, radio exploration of the structure of the CMB was made by WMAP, WILKINSON MICROWAVE ANISOTROPY PROBE.
In 2003 the WMAP was launched. The detectors useful wave length range of the CMB happens to be in a clear gap between two powerful sources of radio waves in our Galaxy. The synchrotron radiation from cosmic ray electrons, first observed by Jansky , falls dramatically at higher radio frequencies and is nearly negligible at millimeter wavelengths, while at shorter wavelengths measured in microns rather than millimeters the sky is again bright with infrared radiation from warm dust in interstellar space. These components of radiation from our galaxy must be removed. Making maps out of a range of radio frequencies, the differences between the maps are used to separate out the components with a spectrum of synchrotron, free-free, or dust radiations. this determines the range of frequencies to be observed in WMAP. WMAP compared the strength of radio signals picked up in two telescopes oriented in opposite directions, mounted in a rotating spacecraft scanning a complete strip of sky. As WMAP slowly orbited round the sun this strip scanned the whole sky, completing a map of structure in 6 months. The spacecraft was launched into an special orbit 900,000 miles from the sun, at point from Earth known as Lagrangian L2; pointed out by Joseph-Louis Lagrange 200 years ago. The WMAP telescopes stayed at the same distance from Earth through the whole l year orbit. It had to avoid any radiation from the Earth and Sun, so the antennas were kept away from Earth and Sun by radiation shields. They settled the telescopes down to a 40o above absolute zero. It really turned out the data, they are still working with it.
By repeatedly scanning the sky, WMAP built up a complete sky map of radio frequencies from 34 to 94 GHZ , filling in the gap, with a very high angular resolution. From the beginning They obtained high-resolution pictures of the CMB, pinning down in detail the spectrum of the CMB. Its first results were published in 2003. It operated for 9 years and achieved a sensitivity 45 times better than COBE. (Seife p. 242; Graham-Smith p. 178)
In 2005, two years after launch the main results were published in what became the most-cited scientific paper of the decade. By measuring the size distribution of the mottled structure of the CMB, the WMAP team were able to determine accurate values of a whole list of cosmological parameters, including the age of the universe, 13.7 Billion years, (since then increased in accuracy to 13.82). They determined there was a lack of curvature of space (Zero at 1 % accuracy), and that Space is flat. They determined the proportions of solid, ordinary matter-baryonic matter, dark matter, dark energy. All this was additional confirmation of the inflation theory, the nucleosynthesis of helium, and much more. This was indeed the beginning of precision cosmology.
In 2009 they launched the PLANCK, (discussed in earlier Parts of this series) becausethe structure of the CMB had not been fully explored, both in the far infrared and in microwave radio. There were new techniques becoming available which increased the sensitivity. They needed more detail of the CMB. To achieve this the whole receiving system had to be much cooler. Telescopes carried into orbit by spacecraft are necessarily limited to size. The radio telescopes could only have about l meter aperture, that would permit wavelengths only around 300 wavelengths across . That limits detail. One cannot go on forever building larger and larger telescopes and putting them into orbit, but they were going to push the limit as much as possible. So with the necessary improvements they launched the PLANCK spacecraft in 2007 intended to map in greater detail the CMB and detect polarization, (Seife p. 242), in the same L2 orbit with great success. It carried radio receivers with the lowest ever internal noise, which improved the sensitivity at the frequencies of 30k, 340, and 70 GHz. The frequency coverage continued into the infrared region, with frequencies from 200 to 857 GHz. The infrared receivers were cooled to the remarkably low temperature of 0.l degree absolute. This sensitivity was so good that structure and polarization could be measured down to a millionth of a total background, so the results could be quoted in units of microkelvins. Amazing. (Graham-Smith pp. 175-177)
Full operation of the PLANCK continued for 2.5 years, only ending when the helium supply for the coolers ran out. They had made five complete scans and an enormous mass of other data had accumulated. Some of this is now becoming available. During that time they had decided what to do next. Larger telescopes could only be built on the ground. And only in a high and dry place. Water vapor was a no-no. They scoured the world for a suitable place. The result was the Chilean Andes and the high plateaus of the South Pole. Not the most desirable places to work. The CMB had emphasized infrared, the WMAP had emphasized radio. PLANCK had used both. The ground based telescopes would be obligated to also use both with improvements. A single infrared reflector several meters across, can have multiple infrared receivers, like those used in PLANCK. The whole telescope can scan slowly over the sky, recording the differences between separate beams. (Graham-Smith p. 178-179 This telescope is now at the South Pole.
SOUTH POLE TELESCOPE (SPT)
At the Antarctic Observatory there are ground based interferometers rather than bolometers as detectors. The DEGREE ANGULAR SCALE INTERFEROMETER (DASI) telescope is very sensitive and first released high-quality data in April 2001. In September 2002 DASI was the first instrument to detect the polarization of the cosmic microwave background. (Seife pp. 241-242) The SOUTH POLE TELESCOPE (SPT) was planned while PLANCK was in orbit and initially began to operate in 2007 and continued to 2011. This was a 10 meter diameter telescope with 960 individual receivers in an array at the focus and could operate at a variety of ranges including spanning the peak brightness of the CMB. The SPT became fully operational in 2012. The results apply to our understanding of the creation and history of the Universe. (Graham-Smith p. 177-178)
Also first deployed at the South Pole in November 2001 was the ARCMINUTE COSMOLOGY BOLOMTER ARRAY RECEIVER, (ACBAR), intended to take advantage of the Sunyaev-Zel-dovich effect to map out the distribution of matter in galaxy clusters. In 2006 another telescope was underway, intended to perform a much more comprehensive Sunyaev-Zel-dovich survey of the skies. (Seife p. 242)
COSMIC BACKGROUND IMAGER (CBI)
The COSMIC BACKGROUND IMAGER (CBI) is similar to DASI, but it is based in Chile and is sensitive to smaller angular scales. It has provided significant support for the inflationary theory, and will be making more important observations that DASI and BOOMERANG were unable to provide. (Seife p. 242) They are trying to cover all the bases.
ATACAMA COSMOLOGY TELESCOPE (ACT)
This telescope, larger than SPT, was built in Chile at 5,000 meters high in the Andes. It was a 10 meter telescope but with a 1024-element receiver array at each of the main three frequencies, 145, 215 and 280 GHz. They are cooled to about the same low temperature achieved in the PLANCK. (Graham-Smith p. 178) See earlier studies in this series for a brief summary of ACT and PLANCK.
VERY SMALL ARRAY (VSA)
Radio receivers are made even more sensitive by the use of interferometers to make them sensitive to only very small structures giving a direct measurement of exactly what is needed. The required maximum interferometer spacing are no more than the apertures of the infrared telescopes with just an overall aperture of no more than 20 meters, so the telescopes look like very small arrays of a dozen or so individual reflectors on a common mounting. The first example of this was called the VERY SMALL ARRAY (VSA). It was built at the mountain observatory of the INSTITUTO CANARIAS DE ASTROHYSICS on the Island of Tenerife. This was followed by the CBI, the COSMIC BACKGROUND IMAGER. This one was located in the Chilean Andes. This is a 13-element interferometer mounted on a 6 meter platform giving maps with a resolution of 4.5 to 10 minutes of arc at radio frequencies between 26 and 36 GHZ. This just means they could detect a whole lot of data and it was all good. The mottled structure of the CMB had a characteristic size, like ripples on a sand beach, giving a width and a height, which can be interpreted mathematically. This is the famous spectrum of the CMB, made initially by the WMAP, and seen in more detail by PLANCK. "This was a tour de force without precedent in the history of science...the theoretical work ...has explained every detail of the spectrum and in so doing has turned cosmology from, arcane speculation into an exact science...The CMB depicts the universe as it was when it was about a thousand times smaller than it is now; we know this because the wavelength of the CMB is about a thousand times longer than it was when it was radiated...The spectacular image ...produced by WMAP and PLANCK represents a slice through the pre-galactic universe at a time 370,000 years after the BIG BANG. " (Graham-Smith pp. 180-181) From there they can work their way back in time to an age of less than a second, at a time when hydrogen of the original fire ball had been combined into helium, and the whole universe had undergone a huge expansion, known as inflation. The two types of telescopes permit the examination of the development of structure (later called elements, stars, galaxies, etc) from an age the fraction of a second to 370,000 years in remarkable detail.
Between the new types of telescopes, infrared and radio, they have revealed the fine structure of the CMB, and opened wide the doors to understanding the beginnings of the creation of the BIG BANG, and much, much more. (Graham-Smith p. 170)
"At about one hundredth of a second, the earliest time about which we can [so far] speak with any confidence, the temperature of the universe was about a hundred thousand million (1011) degrees centigrade." (Weinberg p. 5) "It is in the early universe, especially the first hundredth of a second, that the problems of the theory of elementary particles come together with the problems of cosmology...[In the last fifty years] a detailed theory of the course of events in the early universe has become widely accepted as a 'standard model' ...it is remarkable...to say what the universe was like at the end of the first second or the first minutes or the first year." (Weiberg p. vii)
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