DOCSLIB.ORG

Chapter 11 the Universe

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chapter 11 the Universe Chapter 11 The Universe Is the Universe in an infinite or finite area? Can we find the edges? Required Work: CD - Ho m ew o rk W o rkbo o k: Pages 77 -80 Universe Test (Teacher Provided) Teacher Options: Universe Report 97 For the scientific and faith What is the Universe? The answer: communities, the ultimate question Everything! People trying to determine its concerning the beginning of the cosmos is: limits and boundaries will only expand the How can something be made from nothing? known Universe. How old is the Universe? Science has not able to answer this question. What shape does it have? Is it growing or As of now, only books of faith can answer contacting? Does it matter? these questions. But, science can explain many of the processes that have occurred in A fish knows little about the sea it the Universe. lives in. It does not know the ocean‟s depth or its boundaries. It is familiar with only a For those who believe in intelligent few other life forms in the waters. Does it design and have trouble with scientific care about what it doesn„t know? No. timelines and those who detract faith beliefs such as what comes from the bible, please But, there is a difference between allow me to quote two biblical passages: us and the fish. Whereas fish do not actively Part of a prayer of Moses, NIV Psalm 90:vs. seek knowledge, we, as a species crave this 4 For a thousand years that are in your sight knowledge. The fish do not look for are like a day that has just gone by, or like a boundaries. Our “sea” of understanding watch in the night. NIV 2 Peter: 3 vs. 8-9: seems to have no set boundaries, but “With the Lord, a day is like a thousand nevertheless we continually seek them. years and, a thousand years is like a day.” Also the Islam mentions this idea of time in With each discovery we reach the: Kuran 32.5. According to science, greater awareness of our surroundings, our Jewish ,Christian and Muslim faiths, time is past, future and even our capabilities. We relative. are unique. We are aware of our own demise, yet we seek the possibilities and The following theory about the frontiers that reach beyond our individual beginnings of the Universe and how it lives. In a way, when we stop investigating developed is just that; theory. But much that and asking questions, the Universe‟s is in these theories has been proven through boundaries cease to increase. The cosmos math, observations and the results of consists of what we find and what we experiments. haven‟t found, including our efforts to find Co sm o lo gy even more! (The Beginnings) The ultimate A popular postulation (assertion or q uestio n basis of argument) about the beginning of the Universe is called the Big Bang Theory. When it comes to studying the It is an explanation of how the Universe beginning of the cosmos, some of the began and why it is in its present form important questions are: What are the today. boundaries? How did it form? Where are we in it? What will happen to the It is believed by many scientists that universe? at one time, over 13.73 billion years ago; all 98 matter was compacted into a tiny area. There universe is made up of the following: 73% were no distances or differences between dark energy, 23% dark matter and 4% any of the matter (called singularity.), that visible or directly detectable matter. No one was inside an area smaller than an eraser knows for sure what “dark matter” is but head on a pencil. This time is the called the there are two theories; 1) it is made up of Planck Epoch. dense chunks of heavy metals and or brown dwarfs. 2) It is made up of some type of In the beginning of our Universe, an axions or WIMPS - weakly interacting explosion or more accurately huge and very massive particles. rapid cosmic inflation occurred. It is called the Big Bang. Massive amounts of matter, What scientists still cannot factually with the help of accelerating dark energy answer yet is the following: (mysterious form of energy that so far defies 1. Why was there all that material in the first provable description and may be a result of place? the Big Bang), moved outward faster than 2. Where did the mass come from? the speed of light. In those first few 2. How did it get into such a small area? moments particles formed and then began 3. Why did it explode/expand? cooling. This opening scenario can be 4. How could matter, or anything else, travel measured as a tiny fraction of a second. faster than the speed of light? 5. If there was a Big Bang, where was the A cataclysmic and decisive battle now starting point? took place between matter and antimatter. Most of these opposing elements mutually destroyed each other. But, the winning and surviving matter makes up what we can observe today, including our planet and even ourselves. What’s In It? The surviving matter continued to spread rapidly. Anti-gravitational forces There are three elements that make caused the newly - dispersed matter to hurtle up the perceived universe. The first two are outwards, causing the Universe to expand by connected. One is space - time. This 10 to the fiftieth power in less than a second. includes: all matter, their location, the vacuum of space and the energy. The second As time passed particles that were the element consists of the laws of physics that quarks (the building blocks of neutrons and guide the behavior of space - time. protons) and leptons (the building blocks of electrons), gravitated towards each other and WMAP, which stands for: Wilkinson formed the first atoms. These atoms were in Microwave Anisotropy Probe was the form of heavy hydrogen, the simplest launched in 2001. This probe was sent out type of atom. After millions of years of over a million miles from us, pointed away cooling, the matter and radiation from the Earth, Moon and Sun. It attained a disconnected from each other. reading of the temperature, energy and background radiation levels of the Universe. So, what did we end up with? The It made three sweeps of the cosmos and 99 delivered an incredible amount of data that has taken years to be fully understood. Looking at a big picture of observable By measuring microwaves WMAP matter in the Universe, it looks pretty evenly has given us a picture of what the Universe spread out (homogenously). As we look was like when it was 300,000 years old. It closer at the smaller regions, there is has given us a fossil record of the past. clumping, such as galactic groupings. Looking out into space is like looking back Isotropically, meaning in any direction you in time. Since it takes time for light to travel look, the Universe looks consistently the to our eyes, what we see took place in the same and the radiation levels are evenly past. Light can travel 6 trillion miles in a spread. year. The closest star, other than our Sun, is about three light years away. Some of the What is it doing? stars we see in the night may not even exist anymore! Photon light flows like a stream When astronomers look at distant into our eyes. When the light flows down galaxies they find an interesting thing in that photon river to our retinas, we do not common. Under spectrum analysis, the know it will cease until after the last “drop” galaxies show up as red- shifted, meaning has come and gone. Events such as novas, that they are moving away from us at a very star births and collisions that have occurred rapid rate. As they move away, their speed is in the past take time to reach us. This makes increasing. This conclusion is reached by the telescope in essence, a time machine! observing the aging and lengthening of the photons that travel from these far away Throughout the Universe there seems objects. The longer they travel, the longer to be a uniform residue of radiation. It is and weaker (red shifted) the photons get. uniform and constant. This low level radiation is supposed to be leftovers from the Big Bang. WMAP tells us that the Universe‟s background radiation temperature of 2.7 degrees Kelvin (that is, not much above absolute zero); it is constant and measurable. This could be considered the “smoke” from a smoking gun of the Big Bang. Credit NASA 100 are going. The closer objects (1 million light Co smic Concept: Space/Time years away) are moving at 2000 miles per second away from us. Objects much farther Our Universe has space and time. out (3 billion light years plus) are moving at over 40,000 miles - per second - outward! Perhaps there is a way to travel not only forward in space and time, but also, just But, beyond that, the very space itself as you do when looking at light, travel in our Universe is expanding. A galaxy may back in time. Where would you go and have moved, let‟s say, 1 billion light years. what would like to see? But the space between us and the object may have also expanded several billion light Title: Time and Space Travel years. So, not only are the objects moving, the area in which they exist and between Minimum: 100 words other objects is expanding as well.
Load more

Recommended publications
  • Plasma Physics and Pulsars
    Plasma Physics and Pulsars On the evolution of compact o bjects and plasma physics in weak and strong gravitational and electromagnetic fields by Anouk Ehreiser supervised by Axel Jessner, Maria Massi and Li Kejia as part of an internship at the Max Planck Institute for Radioastronomy, Bonn March 2010 2 This composition was written as part of two internships at the Max Planck Institute for Radioastronomy in April 2009 at the Radiotelescope in Effelsberg and in February/March 2010 at the Institute in Bonn. I am very grateful for the support, expertise and patience of Axel Jessner, Maria Massi and Li Kejia, who supervised my internship and introduced me to the basic concepts and the current research in the field. Contents I. Life-cycle of stars 1. Formation and inner structure 2. Gravitational collapse and supernova 3. Star remnants II. Properties of Compact Objects 1. White Dwarfs 2. Neutron Stars 3. Black Holes 4. Hypothetical Quark Stars 5. Relativistic Effects III. Plasma Physics 1. Essentials 2. Single Particle Motion in a magnetic field 3. Interaction of plasma flows with magnetic fields – the aurora as an example IV. Pulsars 1. The Discovery of Pulsars 2. Basic Features of Pulsar Signals 3. Theoretical models for the Pulsar Magnetosphere and Emission Mechanism 4. Towards a Dynamical Model of Pulsar Electrodynamics References 3 Plasma Physics and Pulsars I. The life-cycle of stars 1. Formation and inner structure Stars are formed in molecular clouds in the interstellar medium, which consist mostly of molecular hydrogen (primordial elements made a few minutes after the beginning of the universe) and dust.
    [Show full text]
  • Beyond the Solar System Homework for Geology 8
    DATE DUE: Name: Ms. Terry J. Boroughs Geology 8 Section: Beyond the Solar System Instructions: Read each question carefully before selecting the BEST answer. Use GEOLOGIC VOCABULARY where APPLICABLE! Provide concise, but detailed answers to essay and fill-in questions. Use an 882-e scantron for your multiple choice and true/false answers. Multiple Choice 1. Which one of the objects listed below has the largest size? A. Galactic clusters. B. Galaxies. C. Stars. D. Nebula. E. Planets. 2. Which one of the objects listed below has the smallest size? A. Galactic clusters. B. Galaxies. C. Stars. D. Nebula. E. Planets. 3. The Sun belongs to this class of stars. A. Black hole C. Black dwarf D. Main-sequence star B. Red giant E. White dwarf 4. The distance to nearby stars can be determined from: A. Fluorescence. D. Stellar parallax. B. Stellar mass. E. Emission nebulae. C. Stellar distances cannot be measured directly 5. Hubble's law states that galaxies are receding from us at a speed that is proportional to their: A. Distance. B. Orientation. C. Galactic position. D. Volume. E. Mass. 6. Our galaxy is called the A. Milky Way galaxy. D. Panorama galaxy. B. Orion galaxy. E. Pleiades galaxy. C. Great Galaxy in Andromeda. 7. The discovery that the universe appears to be expanding led to a widely accepted theory called A. The Big Bang Theory. C. Hubble's Law. D. Solar Nebular Theory B. The Doppler Effect. E. The Seyfert Theory. 8. One of the most common units used to express stellar distances is the A.
    [Show full text]
  • A Star Is Born
    A STAR IS BORN Overview: Students will research the four stages of the life cycle of a star then further research the ramifications of the stage of the sun on Earth. Objectives: The student will: • research, summarize and illustrate the proper sequence in the life cycle of a star; • share findings with peers; and • investigate Earth’s personal star, the sun, and what will eventually come of it. Targeted Alaska Grade Level Expectations: Science [9] SA1.1 The student demonstrates an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [9] SD4.1 The student demonstrates an understanding of the theories regarding the origin and evolution of the universe by recognizing that a star changes over time. [10-11] SA1.1 The student demonstrates an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, analyzing data, developing models, inferring, and communicating. [10] SD4.1 The student demonstrates an understanding of the theories regarding the origin and evolution of the universe by recognizing phenomena in the universe (i.e., black holes, nebula). [11] SD4.1 The student demonstrates an understanding of the theories regarding the origin and evolution of the universe by describing phenomena in the universe (i.e., black holes, nebula). Vocabulary: black dwarf – the celestial object that remains after a white dwarf has used up all of its
    [Show full text]
  • Equation of State of a Dense and Magnetized Fermion System Israel Portillo Vazquez University of Texas at El Paso, [email protected]
    University of Texas at El Paso DigitalCommons@UTEP Open Access Theses & Dissertations 2011-01-01 Equation Of State Of A Dense And Magnetized Fermion System Israel Portillo Vazquez University of Texas at El Paso, [email protected] Follow this and additional works at: https://digitalcommons.utep.edu/open_etd Part of the Physics Commons Recommended Citation Portillo Vazquez, Israel, "Equation Of State Of A Dense And Magnetized Fermion System" (2011). Open Access Theses & Dissertations. 2365. https://digitalcommons.utep.edu/open_etd/2365 This is brought to you for free and open access by DigitalCommons@UTEP. It has been accepted for inclusion in Open Access Theses & Dissertations by an authorized administrator of DigitalCommons@UTEP. For more information, please contact [email protected]. EQUATION OF STATE OF A DENSE AND MAGNETIZED FERMION SYSTEM ISRAEL PORTILLO VAZQUEZ Department of Physics APPROVED: Efrain J. Ferrer , Ph.D., Chair Vivian Incera, Ph.D. Mohamed A. Khamsi, Ph.D. Benjamin C. Flores, Ph.D. Acting Dean of the Graduate School Copyright © by Israel Portillo Vazquez 2011 EQUATION OF STATE OF A DENSE AND MAGNETIZED FERMION SYSTEM by ISRAEL PORTILLO VAZQUEZ, MS THESIS Presented to the Faculty of the Graduate School of The University of Texas at El Paso in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Department of Physics THE UNIVERSITY OF TEXAS AT EL PASO August 2011 Acknowledgements First, I would like to acknowledge the advice and guidance of my mentor Dr. Efrain Ferrer. During the time I have been working with him, the way in which I think about nature has changed considerably.
    [Show full text]
  • Extreme Stars White Dwarfs & Neutron Stars
    Extreme Stars White Dwarfs & Neutron Stars White Dwarfs: • Remnants of low-mass stars • Supported by Electron Degeneracy Pressure • Maximum Mass ~1.4 Msun (Chandrasekhar Mass) Neutron Stars: • Remnants of some post-supernova massive stars • Supported by Neutron Degeneracy Pressure • Pulsar = rapidly spinning magnetized neutron star 1 When electron degeneracy becomes nearly relativistic, equation of state is “softer” and star gets smaller rapidly with mass The Stellar Graveyard Question: What happens to the cores of dead stars? Answer: They continue to collapse until either: • A new pressure law takes hold to halt further collapse & they settle into a new hydrostatic equilibrium. • If too massive they collapse to “a singularity” and become a Black Hole. All of these are seen as the remnants of stellar evolution. 7 Degenerate Gas Law At high density, a new gas law takes over: • Pack many electrons into a tiny volume • These electrons fill all low-energy states • Only high-energy = high-pressure states left Result is a "Degenerate Gas": • Pressure is independent of Temperature. • Compression does not lead to heating. This means that the objects could be very cold but still have enough pressure to maintain a state of Hydrostatic Equilibrium (BIG ROCKS!, well almost…) Can such objects exist? 8 White Dwarfs These are the remnant cores of stars with M < 8 Msun. • Supported against gravity by Electron Degeneracy Pressure • M<4 Msun: C-O White Dwarfs • M=4-8 Msun: O-Ne-Mg White Dwarfs Properties: • Mass < 1.4 Msun • Radius ~ Rearth (<0.02 Rsun) • Density ~ 105-6 g/cc • Escape Speed: 0.02c (2% speed of light) No nuclear fusion or gravitational contraction.
    [Show full text]
  • Chapter 1: How the Sun Came to Be: Stellar Evolution
    Chapter 1 SOLAR PHYSICS AND TERRESTRIAL EFFECTS 2+ 4= Chapter 1 How the Sun Came to Be: Stellar Evolution It was not until about 1600 that anyone speculated that the Sun and the stars were the same kind of objects. We now know that the Sun is one of about 100,000,000,000 (1011) stars in our own galaxy, the Milky Way, and that there are probably at least 1011 galaxies in the Universe. The Sun seems to be a very average, middle-aged star some 4.5 billion years old with our nearest neighbor star about 4 light-years away. Our own location in the galaxy is toward the outer edge, about 30,000 light-years from the galactic center. The solar system orbits the center of the galaxy with a period of about 200,000,000 years, an amount of time we may think of as a Sun-year. In its life so far, the Sun has made about 22 trips around the galaxy; like a 22-year old human, it is still in the prime of its life. Section 1.—The Protostar Current theories hold that about 5 billion years ago the Sun began to form from a huge dark cloud of dust and vapor that included the remnants of earlier stars which had exploded. Under the influence of gravity the cloud began to contract and rotate. The contraction rate near the center was greatest, and gradually a dense central core formed. As the rotation rate increased, due to conservation of angular momentum, the outer parts began to flatten.
    [Show full text]
  • The Sizes of the Stars
    Chapter 8 The Sizes of the Stars The “Plough” in Ursa Major, photographed by Nik Szymanek Look up into the sky, and you will see the stars as tiny, twinkling points. The twinkling is due entirely to the Earth’s atmosphere; from space (or on the Moon) stars do not twinkle (scintillate) at all, and if you have the chance of seeing stars while you are travelling in a high-flying jet you will find that the twinkling is much less then it is at sea level. But with the naked eye, no star appears as anything but a dot. If you use a star as an obvious disk, you may be assured that there is something wrong. Almost certainly the telescope is out of focus. This being so, it takes an effort of the imagina- tion to appreciate that some of the stars are huge enough to contain the whole orbit of the Earth round the Sun – while admittedly others are so tiny that they could fit com- fortably into the ring road of a small city. For the last the programme of 2005 I was joined by Professors Richard Harrison and Lucy Green to say something about the Sun, the only star close enough to be examined in a great deal, and then by Drs John Mason and Barrie Jones, to discuss the sizes of the various types of stars. P. Moore, The Sky at Night, DOI 10.1007/978-1-4419-6409-0_8, 29 © Springer Science+Business Media, LLC 2010 30 8 The Sizes of the Stars If no stars show obvious disks, then how do we measure their diameters? There are various methods.
    [Show full text]
  • The New York Public Library Amazing Scientists: a Book of Answers for Kids
    fm.qxd 11/12/01 1:05 PM Page i THE NEW YORK PUBLIC LIBRARY AMAZING SCIENTISTS A Book of Answers for Kids Jim Callan A Stonesong Press Book John Wiley & Sons, Inc. New York fcopyebk.qxd 12/12/01 11:03 AM Page ii To Polly . my amazing discovery Copyright ©2001 by The New York Public Library and The Stonesong Press, Inc. All rights reserved. Published by John Wiley & Sons, Inc. The name “The New York Public Library” and the representation of the lion appearing in this work are trademarks and the property of The New York Public Library, Astor, Lenox, and Tilden Foundations. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authoriza- tion through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4744. Requests to the Publisher for permission should be addressed to the Permission Department, John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012, (212) 850-6011, fax (212) 850-6008, email: [email protected]. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold with the understanding that the Publisher is not engaged in rendering legal, accounting, or other professional services.
    [Show full text]
  • 1. the Distances to the Most Remote Galaxies Can Be Determined Using
    1. The distances to the most remote galaxies can be determined using: a) galactic parallax. b) spectroscopic parallax. c) proper motion. d) Cepheids. e) none of the above. 2. Generally stars that have low metallicities are considered to be: a) near the end of their lives. b) very young. c) very old. d) a, b, or c — it’s impossible to say. 3. The evidence for the small size of quasars comes from: a) the amount of energy they release. b) their distance from us. c) the rapidity of their luminosity changes. d) comparison with Cepheid variables. e) the magnitude of their redshift. 4. Which of the following stages will the Sun definitely go through as it gets older? a) red giant. b) source of a planetary nebula. c) white dwarf. d) black dwarf. e) all of the above. 5. A star whose temperature is increasing but whose luminosity is roughly constant moves in what direction on the H-R diagram? a) to the right. b) to the left. c) upwards. d) downwards. e) none of the above, the star doesn’t move on the H-R diagram. 6. Which type of galaxy is observed to contain mostly older stars? a) spiral b) elliptical c) dwarf elliptical d) irregular e) none of the above 7. What remains after a supernova? a) a main sequence star. b) a white dwarf. c) a neutron star. d) a black hole. e) either c) or d), depending on the mass of the star. 8. The Andromeda Galaxy (our nearest spiral neighbour) has spectral lines that show a blue shift.
    [Show full text]
  • Astronomy General Information
    ASTRONOMY GENERAL INFORMATION HERTZSPRUNG-RUSSELL (H-R) DIAGRAMS -A scatter graph of stars showing the relationship between the stars’ absolute magnitude or luminosities versus their spectral types or classifications and effective temperatures. -Can be used to measure distance to a star cluster by comparing apparent magnitude of stars with abs. magnitudes of stars with known distances (AKA model stars). Observed group plotted and then overlapped via shift in vertical direction. Difference in magnitude bridge equals distance modulus. Known as Spectroscopic Parallax. SPECTRA HARVARD SPECTRAL CLASSIFICATION (1-D) -Groups stars by surface atmospheric temp. Used in H-R diag. vs. Luminosity/Abs. Mag. Class* Color Descr. Actual Color Mass (M☉) Radius(R☉) Lumin.(L☉) O Blue Blue B Blue-white Deep B-W 2.1-16 1.8-6.6 25-30,000 A White Blue-white 1.4-2.1 1.4-1.8 5-25 F Yellow-white White 1.04-1.4 1.15-1.4 1.5-5 G Yellow Yellowish-W 0.8-1.04 0.96-1.15 0.6-1.5 K Orange Pale Y-O 0.45-0.8 0.7-0.96 0.08-0.6 M Red Lt. Orange-Red 0.08-0.45 *Very weak stars of classes L, T, and Y are not included. -Classes are further divided by Arabic numerals (0-9), and then even further by half subtypes. The lower the number, the hotter (e.g. A0 is hotter than an A7 star) YERKES/MK SPECTRAL CLASSIFICATION (2-D!) -Groups stars based on both temperature and luminosity based on spectral lines.
    [Show full text]
  • Stellar Remnants
    Star Evolution Nebula • The makings of a star • Made of dust and gas. Protostar • A nebula begins to collapse. • Nuclear fusion converts hydrogen to helium. Sequence of Star Birth • As nuclear fusion occurs, the star begins to burn. • This burning changes gravitational energy into heat energy. The main factor to shape a star’s fate is it’s mass. Main Sequence Star • As star is burning, it is known as a main sequence star. • May be main sequence for millions of years (large stars) or billions of years (small and medium stars). • As a main sequence it is burning H and producing He Main Sequence Star • While a main sequence star, there is a battle between gravity and gas pressure Gas pressure from the burning of the star is pushing outward away from the core Gravity is trying to collapse the star Low Mass Stars • When the H has been used up, there is not enough pressure to prevent gravity from collapsing the star and forming a white dwarf Medium Mass Stars • Medium mass stars burn hot enough to use He as a fuel as well as H • Medium mass stars expand to form a red giant when their H is nearly gone • When all of the H & He is used, the star collapses to form a white dwarf High Mass Stars • Massive stars quickly use up their H & He fuel • When the fuel is gone, the star collapses so rapidly that it explodes as a Supernova. The Sun’s Fate • The sun is an adult main sequence star. –What will happen to it in the next 4 billion years? Stellar Remnants White Dwarfs continue to burn very hot and therefore are very bright even though they are very small Stellar Remnants http://www.edwinhubble.com/s Stellar Remnants are what’s left pace_pics/planetary_nebula_IC _418_350.jpg when a star “dies” Planetary Nebula is the burning gas surrounding a white dwarf star http://nssdc.gsfc.nasa.gov/image/ Planetary nebula are associated with astro/hst_stingray_nebula.jpg medium mass stars (i.e.
    [Show full text]
  • Near-Death Studies and Modern Physics
    Near-Death Studies and Modern Physics Craig R. Lundahl, Ph.D. Western New Mexico University Arvin S. Gibson Kaysville, UT ABSTRACT: The fields of near-death studies and modern physics face common dilemmas: namely, how to account for the corroborative nature of many near death experiences or of the anthropic disposition of the universe without allow ing for some otherworldly existence and/or some guiding intelligence. Extreme efforts in both fields to explain various phenomena by contemporary scientific methods and theories have been largely unsuccessful. This paper exposes some of the principal problem areas and suggests a greater collaboration between the two fields. Specific illustrations are given where collaborative effort might be fruitful. The paper also suggests a broader perspective in performing the research, one that places greater emphasis on an otherworldly thrust in future research. Efforts to explain the near-death experience (NDE) have tended to fo cus on theories to explain the NDE as a biological, mental, psychological or social phenomena and theories that explain it as a real occurrence. These attempts have been proposed by researchers and theorists from a number of different fields. They tend to fall into a number of cat egories of explanation that include cultural, pharmacological, physio logical, neurological, psychological, and religious. These many attempts at explanation include such factors as prior social or cultural conditioning (Rodin, 1980), drugs and sensory de privation (Grof and Halifax, 1977; Palmer, 1978; Siegel, 1980), cere bral anoxia or hypoxia, temporal lobe seizures, and altered states of Craig R. Lundahl, Ph.D., is Professor Emeritus of Sociology and Business Admin istration and Chair Emeritus of the Department of Social Sciences at Western New Mexico University in Silver City, New Mexico.
    [Show full text]