Millions Of Light Years Research Articles

The Black Ribbon

The Black Ribbon

Astronomy: Ancient Galaxy Walls Go Up; Will Theories Tumble Down?

IRVINE, CALIFORNIA --New observations described at a National Academy of Sciences colloquium here suggest that giant walls of galaxies, hundreds of millions of light-years long, may have crisscrossed the universe when it was just 15% of its present age. Such structures are similar to what we see today, which raises a problem for theorists: If gravity hasn't radically resculpted the universe over time, that implies that it may have far less mass than theorists prefer. That is in line with evidence of a scarcity of mass in the nearby universe but at odds with one measurement of how fast the cosmic expansion rate is changing, which hints at a much higher density of matter ( see p. 37 ).

Microwave radiometry and applications

The radiometry in general is a method of detecting the radiation of matter. All material bodies and substances radiate energy in the form of electromagnetic waves according to Planck s Law. The frequency spectrum of such thermal radiation is determined, beyond the properties of a blackbody, by the emissivity of surfaces and by the temperature of a particular body. Also, its reflectivity and dispersion take part. Investigating the intensity of radiation and its spectral distribution, one may determine the temperature and characterize the radiating body as well as the ambient medium, all independently of distance. With the above possibilities, the radiometry represents a base of scientific method called remote sensing. Utilizing various models, temperature of distant bodies and images of observed scenes can be determined from the spatial distribution of radiation. In this method, two parameters are of paramount importance: An instrument usable to conduct radiometric observations thus consists of two basic elements: a detector or radiometer, which determines the temperature resolution, and an antenna which determines the angular or spatial resolution. For example, a photographic camera consists of an objective lens (antenna) and of a sensitive element (a film or a CCD). In remote sensing, different lenses and reflectors and different sensors are employed, both adjusted to a particular spectrum region in which certain important features of observed bodies and scenes are present: frequently, UV and IR bands are used. The microwave radiometry utilizes various types of antennas and detectors and provides some advantages in observing various scenes: the temperature resolution is recently being given in milikelvins, while the range extends from zero to millions of Kelvins. Microwaves also offer a chance to penetrate surfaces of non-metallic objects down to some wavelengths, by which it is advantageous in certain applications over e.g. IR waves. An extreme example of capabilities of the microwave radiometry is found in radio astronomy, where it determines temperatures and spectral features of bodies so remote that their distance from us is measured in millions of light years. Other apparatus serve in remote observation of Earth s resources: soils, water regions and atmosphere. Similar systems also have found applications in medical studies of human body, e.g. in cancer and inflammation diagnostics. The paper presents a background of the radiometric method, comments to equipment design and outlines some of the applications.

Atom-Probe Field Ion Microscopy

Scientists are always pushing to new frontiers, which often involve questions about phenomena that occur on very large or very small scales. Astronomers search for new stars millions of light-years away in a quest to learn how these stars and the universe were born, and particle physicists look at elementary particles of size less than 10−17 cm in an effort to understand fundamental interactions. Meanwhile, however, many biologists, chemists and condensed matter physicists are trying to understand natural phenomena that we encounter every day and that occur on some intermediate scale. Questions at this scale are posed in terms of interactions between electrons or atoms and chemical bonds or in terms of atomic theories. The motivation is not only scientific curiosity but also a desire to discover new effects, create new molecules and materials, and develop new technologies that may benefit society. Although a single interaction, electromagnetism, determines the chemical and physical properties of molecules and materials, nature manifests electromagnetic forces in so many forms and in so many phenomena that many of them are by no means understood. One of the powerful tools at our disposal for studies on the microscopic scale or atomic scale is the atomic-resolution microscope.

An Exercise on the Use of Cepheid Variable Stars As Astronomical Distance Indicators for Introductory Earth-Science Classes

In an effort to provide additional opportunities for active, cooperative learning by students in introductory earth-science classes, I have developed an exercise on the use of cepheid-variable stars as distance indicators. Cepheid-variable stars were the key to Edwin P. Hubble's determination in 1924 that the so-called “spiral nebulae” (which were thought at the time by many astronomers to be located within our Milky Way galaxy) are, in fact, “spiral galaxies” that are located millions of light years away from the earth, well outside our galaxy. This determination by Hubble was one of the most significant astronomical discoveries ever made and enlarged our concept of the universe enormously. Five years later, Hubble demonstrated that the Universe is expanding. The thing that makes cepheid-variable stars so useful is that (as discovered by Henrietta Swan Leavitt) their period of variability is related to their luminosity. In other words, if one can determine the period of a cepheid, its luminosity can be r...

Particle Astrophysics

Particle astrophysics emerged in the 1980s as a new field at the junction of high-energy astrophysics, cosmology and particle physics. This new experimental, observational and theoretical discipline concerns itself, for example, with the nature of dark matter; the detection of neutrinos from the Sun and from supernovae; the evidence for powerful acceleration mechanisms in the vicinity of neutron stars; and the suggestion that quantum fluctuation and topological singularities in the first moments of the cosmos played a role in the formation of the great structures we see today stretching over hundreds of millions of light-years.

Number Sense

Good number sense is fundamental for success in estimation, approximation, and problem solving. We need to develop a sense of large numbers because newspaper and television news reports contain many references to large quantities. The federal budget is expressed in billions and trillions of dollars, space distances in millions of light years or trillions of miles, computer speeds in nanoseconds (1 nanosecond = 1 billionth of a second), computer storage memory in gigabytes (1 gigabyte = 1 billion bytes), world populations in millions and billions of individuals, and nuclear weapons in millions of tons of TNT. Clearly, the average citizen needs a well-developed sense of large numbers to understand many of the news items that invade the home. Large-number concepts a re appropriate for development in upper elementary school, high school, and beyond. This article presents some examples to enhance a sense of large numbers in middle and high school students.

E. T.: A Cosmic Myth for Space-Age Children

E. T.:A Cosmic Myth for Space-Age Children Millicent Lenz While the director of a film may not be a reliable critic of it, his comments can be illuminating. In fact, Steven Spielberg has identified some of the more obvious themes of his phenomenally successful film, E. T. "To me," he says, "represents our generation's Wizard of Oz or Peter Pan. I think it represents a kind of contemporary social fantasy that doesn't play down to kids the way fantasies played down to me when I was growing up. Essentially, it treats everything very realistically and very importantly." It says, "Don't get locked into the cynicism of the technological 80s." Just when we feel that we're all becoming little microchips, 'E.T.' comes along and proves to everybody that we're all made of flesh and blood and that we were all born with and will die with a heart. Our society is becoming much too technical. I think E.T. is the humanistic answer to the technical revolution.1 This romantic statement of the old opposition between the head and the heart, with E.T. representing the heart, grossly oversimplifies the nature of E. T. as he is presented in the movie, where he comes from a civilization technologically far advanced over our own: he appears to represent Heart working in harmony with Head, not in opposition to it. Nor is Spielberg as anti-technology as this statement suggests, for in the same interview he speaks out in favor of more financial support for NASA and identifies E.T. as "my answer to the stalled space program"—helping to make space "more accessible to the imagination." But E.T., with his heart-light and his healing finger, certainly is a kind of cosmic father/mother, signifying a nurturing universe. Elliott finds in E.T. a surrogate father, filling "the gap left by a father who flew to Mexico with another woman." But by extension of the imagination, E.T. "transforms the father-son relationship into something much more cosmic."2 E.T.'s identification with nurturant qualities, with goodness and lovability, is made more striking by his unattractive physical appearance. Speilberg has said we realate not to his outside appearance "but the goodness inside him." Even though he is "a squashy little mensch"3 he is like the frog of the folk tale, transformed by the power of love into the handsome prince who saves the princess; but in this case it is Elliott whom he saves from "his closed-up anger" and points in the direction of "the promise of real manhood."4 Spielberg's thoughts bring out two related themes, expressed through both E.T. and Elliott: first, the search for a home, and second, the search for either father or a child, depending on whether we choose to look through the eyes of E.T. or the eyes of Elliott. One of the special fascinations of the film grows out of the "telepathic sympathy" between the two. The ancient botanist, star-child of a universe millions of light-years away,5 and the young boy, a human child, develop a perfect sympathy that transcends space and time and bridges the great gulfs between species and generations. But E.T. says more than that; the film presents certain timeless mythic patterns in a way that links us, not only to our mythological past, but also, perhaps, to our space-conscious future. On the universal mythological level, the most important and powerful theme in the story is "descent," the heroic initiation into the mystery of death, followed by "ascent," the rebirth into new life: in short, it is a drama of death and resurrection. While this magnificent subject is handled clumsily, it is the essence of E.T.'s power as a fantasy in the romantic mode. Given the nature of the film, there is a risk in overinterpreting it, in making a basically entertaining, fragile script bear the weight of too heavy an exegesis. But for better or for worse, E.T. has so fastened itself to my imagination, like a persistent ghost, that I must exorcise it; and I know of...

The Night Sky in March

THE date of the Spring Equinox is March 21d 7h U.T. The moon is new on March 2 at 5·7h, and on March 31 at 18·9h ; full moon occurs on March 16 at 5·3h. Lunar conjunctions with the planets occur as follows: on March 4d 6h with Saturn; on March 5d 15h with Mars ; on March 28d 7h with Jupiter. On March 18d 0h Venus and Saturn are in conjunction ; on March 20d 5h Mercury and Venus, and on March 28d 22h Mars and Uranus. The occasion of the fairly close proximity of Uranus to Mars may be used for locating the latter with binoculars, the magnitude of Uranus being about 6·0 and that of Mars about 1·5. Mars sets at 21·7h. Mercury is at greatest eastern elongation on April 2, so that towards the end of March there is a chance of seeing this elusive planet in the evening twilight. Venus is likewise an evening star, but sets less than one hour after the sun until the latter part of March. Saturn is passing out of view as an evening star and is in conjunction with the sun on March 29, but Jupiter now rises in the early dawn as a bright star of magnitude – 1·6. In the late evening in the middle of March, the bright stars of Orion and Sirius and Procyon are being lost to view towards the west, but there are compensations. For a small telescope, the double star, Castor, is an excellent subject for observation, γVirginis is another well-known binary the period of which is about 180 years. 12 Lyncis (R.A. 6h 39m, Dec. 59° 31' N). and 11 Monocerotis (R.A. 6h 25m, Dec. 7° 0' S.) are both triple stars. There is a stellar cluster, Messier 35, north-preceding η Geminorum, and the cluster Messier 44, better known as Prsesepe, south-preceding γ Cancri. Away from the obscuration effects of the Milky Way, remote space can be explored with powerful photographic telescopes. In Leo, there is a remarkable group of extra-galactic nebulae (NOG 3185, 3187, 3190 and 3193) exhibiting a variety of types and at a distance of about 7½ million light years from the earth. Another group in Bootes and one in Ursa Major (overhead about midnight in the middle of March) give Doppler displacements in the spectra of the component nebulae equivalent to recessional velocities of about one-seventh the velocity of light itself ; the inferred distances are of the order 230 to 240 millions of light years.