Matter, Dark Matter, and Anti-Matter

Download Matter, Dark Matter, and Anti-Matter PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 144198822X
Total Pages : 188 pages
Book Rating : 4.4/5 (419 download)

DOWNLOAD NOW!


Book Synopsis Matter, Dark Matter, and Anti-Matter by : Alain Mazure

Download or read book Matter, Dark Matter, and Anti-Matter written by Alain Mazure and published by Springer Science & Business Media. This book was released on 2011-11-16 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: For over ten years, the dark side of the universe has been headline news. Detailed studies of the rotation of spiral galaxies, and 'mirages' created by clusters of galaxies bending the light from very remote objects, have convinced astronomers of the presence of large quantities of dark (unseen) matter in the cosmos. The most striking fact is that they seem to compromise about 95% of the matter/energy content of the universe. As for ordinary matter, although we are immersed in a sea of dark particles, including primordial neutrinos and photons from fossil cosmological radiation, both we and our environment are made of ordinary, 'baryonic' matter. Authors Mazure and Le Brun present the inventory of matter, baryonic and exotic, and investigating the nature and fate of matter's twin, anti-matter. They show how technological progress has been a result of basic research, in tandem with the evolution of new ideas, and how the combined effect of these advances might help lift the cosmic veil.

Dark Matter and Dark Energy

Download Dark Matter and Dark Energy PDF Online Free

Author :
Publisher : Icon Books
ISBN 13 : 1785785699
Total Pages : 121 pages
Book Rating : 4.7/5 (857 download)

DOWNLOAD NOW!


Book Synopsis Dark Matter and Dark Energy by : Brian Clegg

Download or read book Dark Matter and Dark Energy written by Brian Clegg and published by Icon Books. This book was released on 2019-08-08 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'Clear and compact ... It's hard to fault as a brief, easily digestible introduction to some of the biggest questions in the Universe' Giles Sparrow, BBC Four's The Sky at Night , Best astronomy and space books of 2019: 5/5 All the matter and light we can see in the universe makes up a trivial 5 per cent of everything. The rest is hidden. This could be the biggest puzzle that science has ever faced. Since the 1970s, astronomers have been aware that galaxies have far too little matter in them to account for the way they spin around: they should fly apart, but something concealed holds them together. That 'something' is dark matter - invisible material in five times the quantity of the familiar stuff of stars and planets. By the 1990s we also knew that the expansion of the universe was accelerating. Something, named dark energy, is pushing it to expand faster and faster. Across the universe, this requires enough energy that the equivalent mass would be nearly fourteen times greater than all the visible material in existence. Brian Clegg explains this major conundrum in modern science and looks at how scientists are beginning to find solutions to it.

Connecting Quarks with the Cosmos

Download Connecting Quarks with the Cosmos PDF Online Free

Author :
Publisher : National Academies Press
ISBN 13 : 030917113X
Total Pages : 222 pages
Book Rating : 4.3/5 (91 download)

DOWNLOAD NOW!


Book Synopsis Connecting Quarks with the Cosmos by : National Research Council

Download or read book Connecting Quarks with the Cosmos written by National Research Council and published by National Academies Press. This book was released on 2003-03-12 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances made by physicists in understanding matter, space, and time and by astronomers in understanding the universe as a whole have closely intertwined the question being asked about the universe at its two extremesâ€"the very large and the very small. This report identifies 11 key questions that have a good chance to be answered in the next decade. It urges that a new research strategy be created that brings to bear the techniques of both astronomy and sub-atomic physics in a cross-disciplinary way to address these questions. The report presents seven recommendations to facilitate the necessary research and development coordination. These recommendations identify key priorities for future scientific projects critical for realizing these scientific opportunities.

The Cosmic Cocktail

Download The Cosmic Cocktail PDF Online Free

Author :
Publisher : Princeton University Press
ISBN 13 : 0691169187
Total Pages : 264 pages
Book Rating : 4.6/5 (911 download)

DOWNLOAD NOW!


Book Synopsis The Cosmic Cocktail by : Katherine Freese

Download or read book The Cosmic Cocktail written by Katherine Freese and published by Princeton University Press. This book was released on 2016-05-17 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inside story of the epic quest to solve the mystery of dark matter The ordinary atoms that make up the known universe—from our bodies and the air we breathe to the planets and stars—constitute only 5 percent of all matter and energy in the cosmos. The rest is known as dark matter and dark energy, because their precise identities are unknown. The Cosmic Cocktail is the inside story of the epic quest to solve one of the most compelling enigmas of modern science—what is the universe made of?—told by one of today's foremost pioneers in the study of dark matter. Blending cutting-edge science with her own behind-the-scenes insights as a leading researcher in the field, acclaimed theoretical physicist Katherine Freese recounts the hunt for dark matter, from the discoveries of visionary scientists like Fritz Zwicky—the Swiss astronomer who coined the term "dark matter" in 1933—to the deluge of data today from underground laboratories, satellites in space, and the Large Hadron Collider. Theorists contend that dark matter consists of fundamental particles known as WIMPs, or weakly interacting massive particles. Billions of them pass through our bodies every second without us even realizing it, yet their gravitational pull is capable of whirling stars and gas at breakneck speeds around the centers of galaxies, and bending light from distant bright objects. Freese describes the larger-than-life characters and clashing personalities behind the race to identify these elusive particles. Many cosmologists believe we are on the verge of solving the mystery. The Cosmic Cocktail provides the foundation needed to fully fathom this epochal moment in humankind’s quest to understand the universe.

Particle Dark Matter

Download Particle Dark Matter PDF Online Free

Author :
Publisher : Cambridge University Press
ISBN 13 : 0521763681
Total Pages : 763 pages
Book Rating : 4.5/5 (217 download)

DOWNLOAD NOW!


Book Synopsis Particle Dark Matter by : Gianfranco Bertone

Download or read book Particle Dark Matter written by Gianfranco Bertone and published by Cambridge University Press. This book was released on 2010-01-07 with total page 763 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the dark matter problem in particle physics, astrophysics and cosmology for graduate students and researchers.

Dark Matter and Dark Energy

Download Dark Matter and Dark Energy PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 9048186854
Total Pages : 413 pages
Book Rating : 4.0/5 (481 download)

DOWNLOAD NOW!


Book Synopsis Dark Matter and Dark Energy by : Sabino Matarrese

Download or read book Dark Matter and Dark Energy written by Sabino Matarrese and published by Springer Science & Business Media. This book was released on 2011-02-10 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together reviews from leading international authorities on the developments in the study of dark matter and dark energy, as seen from both their cosmological and particle physics side. Studying the physical and astrophysical properties of the dark components of our Universe is a crucial step towards the ultimate goal of unveiling their nature. The work developed from a doctoral school sponsored by the Italian Society of General Relativity and Gravitation. The book starts with a concise introduction to the standard cosmological model, as well as with a presentation of the theory of linear perturbations around a homogeneous and isotropic background. It covers the particle physics and cosmological aspects of dark matter and (dynamical) dark energy, including a discussion of how modified theories of gravity could provide a possible candidate for dark energy. A detailed presentation is also given of the possible ways of testing the theory in terms of cosmic microwave background, galaxy redshift surveys and weak gravitational lensing observations. Included is a chapter reviewing extensively the direct and indirect methods of detection of the hypothetical dark matter particles. Also included is a self-contained introduction to the techniques and most important results of numerical (e.g. N-body) simulations in cosmology. " This volume will be useful to researchers, PhD and graduate students in Astrophysics, Cosmology Physics and Mathematics, who are interested in cosmology, dark matter and dark energy.

Searching for Dark Matter with Cosmic Gamma Rays

Download Searching for Dark Matter with Cosmic Gamma Rays PDF Online Free

Author :
Publisher : Morgan & Claypool Publishers
ISBN 13 : 1681742705
Total Pages : 82 pages
Book Rating : 4.6/5 (817 download)

DOWNLOAD NOW!


Book Synopsis Searching for Dark Matter with Cosmic Gamma Rays by : Andrea Albert

Download or read book Searching for Dark Matter with Cosmic Gamma Rays written by Andrea Albert and published by Morgan & Claypool Publishers. This book was released on 2016-09-06 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Searching for Dark Matter with Cosmic Gamma Rays summarizes the evidence for dark matter and what we can learn about its particle nature using cosmic gamma rays. It has almost been 100 years since Fritz Zwicky first detected hints that most of the matter in the Universe that doesn't directly emit or reflect light. Since then, the observational evidence for dark matter has continued to grow. Dark matter may be a new kind of particle that is governed by physics beyond our Standard Model of particle physics. In many models, dark matter annihilation or decay produces gamma rays. There are a variety of instruments observing the gamma-ray sky from tens of MeV to hundreds of TeV. Some make deep, focused observations of small regions, while others provide coverage of the entire sky. Each experiment offers complementary sensitivity to dark matter searches in a variety of target sizes, locations, and dark matter mass scales. We review results from recent gamma-ray experiments including anomalies some have attributed to dark matter. We also discuss how our gamma-ray observations complement other dark matter searches and the prospects for future experiments.

Antimatter

Download Antimatter PDF Online Free

Author :
Publisher : Springer Nature
ISBN 13 : 3030677915
Total Pages : 296 pages
Book Rating : 4.0/5 (36 download)

DOWNLOAD NOW!


Book Synopsis Antimatter by : Beatriz Gato-Rivera

Download or read book Antimatter written by Beatriz Gato-Rivera and published by Springer Nature. This book was released on 2021-04-10 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Antimatter is one of the most fascinating aspects of Particle Physics, and matter-antimatter annihilation the most energetic process in the universe. If they existed, everyday objects made of antimatter would look exactly like those made of ordinary matter, as would antimatter stars. We live surrounded by antimatter, since showers of matter and antimatter particles fall incessantly on the Earth's surface, some of them penetrating our buildings. Furthermore, many things around us - bananas, for example - actually emit antielectrons. This book first introduces the essentials of particle physics and the nature of particles and antiparticles. It describes the discovery of antimatter particles and explains how they are produced, where they are found, and how antistars could be spotted; it also introduces cosmic rays, particle accelerators, dark matter, dark energy and nuclear reactions in stars. The enigma of the matter-antimatter asymmetry in the Universe is discussed as are the very real applications of antimatter in hospitals, in industry and in cutting-edge research and technology, Non-specialist readers will find here a wealth of fascinating and accessible information to deepen their appreciation of antimatter.​

Matter, Antimatter, and Dark Matter

Download Matter, Antimatter, and Dark Matter PDF Online Free

Author :
Publisher : World Scientific
ISBN 13 : 981277680X
Total Pages : 269 pages
Book Rating : 4.8/5 (127 download)

DOWNLOAD NOW!


Book Synopsis Matter, Antimatter, and Dark Matter by : Roberto Battiston

Download or read book Matter, Antimatter, and Dark Matter written by Roberto Battiston and published by World Scientific. This book was released on 2002 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the progress in cosmic ray physics following the recent results obtained by balloon, satellite and underground experiments. The following topics are reviewed: Composition and propagation of cosmic rays, trapping of charged particles in the earth''s magnetic field, atmospheric neutrinos, and high energy photon measurements in space.

The Mystery of the Missing Antimatter

Download The Mystery of the Missing Antimatter PDF Online Free

Author :
Publisher : Princeton University Press
ISBN 13 : 1400835712
Total Pages : 293 pages
Book Rating : 4.4/5 (8 download)

DOWNLOAD NOW!


Book Synopsis The Mystery of the Missing Antimatter by : Helen R. Quinn

Download or read book The Mystery of the Missing Antimatter written by Helen R. Quinn and published by Princeton University Press. This book was released on 2010-01-01 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the first fractions of a second after the Big Bang lingers a question at the heart of our very existence: why does the universe contain matter but almost no antimatter? The laws of physics tell us that equal amounts of matter and antimatter were produced in the early universe—but then something odd happened. Matter won out over antimatter; had it not, the universe today would be dark and barren. But how and when did this occur? In The Mystery of the Missing Antimatter, Helen Quinn and Yossi Nir guide readers into the very heart of this mystery—and along the way offer an exhilarating grand tour of cutting-edge physics.

Dark Matter and the Dinosaurs

Download Dark Matter and the Dinosaurs PDF Online Free

Author :
Publisher : HarperCollins
ISBN 13 : 0062328514
Total Pages : 359 pages
Book Rating : 4.0/5 (623 download)

DOWNLOAD NOW!


Book Synopsis Dark Matter and the Dinosaurs by : Lisa Randall

Download or read book Dark Matter and the Dinosaurs written by Lisa Randall and published by HarperCollins. This book was released on 2015-10-27 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: “Takes readers on illuminating scientific adventure, beginning sixty-six million years ago, that connects dinosaurs, comets, DNA, and the future of the planet.” —Huffington Post In this brilliant exploration of our cosmic environment, the renowned particle physicist and New York Times–bestselling author of Warped Passages and Knocking on Heaven’s Door uses her research into dark matter to illuminate the startling connections between the furthest reaches of space and life here on Earth. Sixty-six million years ago, an object the size of a city descended from space to crash into Earth, creating a devastating cataclysm that killed off the dinosaurs, along with three-quarters of the other species on the planet. What was its origin? In Dark Matter and the Dinosaurs, Lisa Randall proposes it was a comet that was dislodged from its orbit as the Solar System passed through a disk of dark matter embedded in the Milky Way. In a sense, it might have been dark matter that killed the dinosaurs. Working through the background and consequences of this proposal, Randall shares with us the latest findings—established and speculative—regarding the nature and role of dark matter and the origin of the Universe, our galaxy, our Solar System, and life, along with the process by which scientists explore new concepts. In Dark Matter and the Dinosaurs, Randall tells a breathtaking story that weaves together the cosmos’ history and our own, illuminating the deep relationships that are critical to our world and the astonishing beauty inherent in the most familiar things. “Randall has woven a beautiful account of how life on Earth is intimately connected to the cosmos.” —The Daily Telegraph (UK)

We Have No Idea

Download We Have No Idea PDF Online Free

Author :
Publisher : Penguin
ISBN 13 : 0735211523
Total Pages : 369 pages
Book Rating : 4.7/5 (352 download)

DOWNLOAD NOW!


Book Synopsis We Have No Idea by : Jorge Cham

Download or read book We Have No Idea written by Jorge Cham and published by Penguin. This book was released on 2018-05-08 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepare to learn everything we still don’t know about our strange and mysterious universe Humanity's understanding of the physical world is full of gaps. Not tiny little gaps you can safely ignore —there are huge yawning voids in our basic notions of how the world works. PHD Comics creator Jorge Cham and particle physicist Daniel Whiteson have teamed up to explore everything we don't know about the universe: the enormous holes in our knowledge of the cosmos. Armed with their popular infographics, cartoons, and unusually entertaining and lucid explanations of science, they give us the best answers currently available for a lot of questions that are still perplexing scientists, including: * Why does the universe have a speed limit? * Why aren't we all made of antimatter? * What (or who) is attacking Earth with tiny, superfast particles? * What is dark matter, and why does it keep ignoring us? It turns out the universe is full of weird things that don't make any sense. But Cham and Whiteson make a compelling case that the questions we can't answer are as interesting as the ones we can. This fully illustrated introduction to the biggest mysteries in physics also helpfully demystifies many complicated things we do know about, from quarks and neutrinos to gravitational waves and exploding black holes. With equal doses of humor and delight, Cham and Whiteson invite us to see the universe as a possibly boundless expanse of uncharted territory that's still ours to explore.

Dark Matter

Download Dark Matter PDF Online Free

Author :
Publisher : Ballantine Books
ISBN 13 : 1101904232
Total Pages : 370 pages
Book Rating : 4.1/5 (19 download)

DOWNLOAD NOW!


Book Synopsis Dark Matter by : Blake Crouch

Download or read book Dark Matter written by Blake Crouch and published by Ballantine Books. This book was released on 2016-07-26 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: NEW YORK TIMES BESTSELLER • COMING SOON TO APPLE TV+ • A “mind-blowing” (Entertainment Weekly) speculative thriller about an ordinary man who awakens in a world inexplicably different from the reality he thought he knew—from the author of Upgrade, Recursion, and the Wayward Pines trilogy “Are you happy with your life?” Those are the last words Jason Dessen hears before the kidnapper knocks him unconscious. Before he awakens to find himself strapped to a gurney, surrounded by strangers in hazmat suits. Before a man he’s never met smiles down at him and says, “Welcome back, my friend.” In this world he’s woken up to, Jason’s life is not the one he knows. His wife is not his wife. His son was never born. And Jason is not an ordinary college professor but a celebrated genius who has achieved something remarkable. Something impossible. Is it this life or the other that’s the dream? And even if the home he remembers is real, how will Jason make it back to the family he loves? From the bestselling author Blake Crouch, Dark Matter is a mind-bending thriller about choices, paths not taken, and how far we’ll go to claim the lives we dream of.

Dark Matter

Download Dark Matter PDF Online Free

Author :
Publisher : CRC Press
ISBN 13 : 1466572116
Total Pages : 271 pages
Book Rating : 4.4/5 (665 download)

DOWNLOAD NOW!


Book Synopsis Dark Matter by : Debasish Majumdar

Download or read book Dark Matter written by Debasish Majumdar and published by CRC Press. This book was released on 2014-08-27 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark Matter: An Introduction tackles the rather recent but fast-growing subject of astroparticle physics, encompassing three main areas of fundamental physics: cosmology, particle physics, and astrophysics. Accordingly, the book discusses symmetries, conservation laws, relativity, and cosmological parameters and measurements, as well as the astrophysical behaviors of galaxies and galaxy clusters that indicate the presence of dark matter and the possible nature of dark matter distribution. This succinct yet comprehensive volume: Addresses all aspects essential to the study of dark matter Explores particle candidates for cold dark matter beyond the theory of the standard model, providing examples of basic extensions and introducing theories such as supersymmetry and extra dimensions Explains—in simple text and mathematical formulations—calculation of the freeze-out temperature of a dark matter species and its relic density Provides theoretical background for dark matter scattering off a target, event rate calculation, and dark matter annihilation essential to study direct and indirect detection of dark matter Complete with a detailed review of the latest dark matter experiments and techniques, Dark Matter: An Introduction is an ideal text for beginning researchers in the field as well as for general readers with an inquisitive mind, as the important topic of astroparticle physics is treated both pedagogically and with deeper insight.

Galileo Unbound

Download Galileo Unbound PDF Online Free

Author :
Publisher : Oxford University Press
ISBN 13 : 0192528505
Total Pages : 384 pages
Book Rating : 4.1/5 (925 download)

DOWNLOAD NOW!


Book Synopsis Galileo Unbound by : David D. Nolte

Download or read book Galileo Unbound written by David D. Nolte and published by Oxford University Press. This book was released on 2018-07-12 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galileo Unbound traces the journey that brought us from Galileo's law of free fall to today's geneticists measuring evolutionary drift, entangled quantum particles moving among many worlds, and our lives as trajectories traversing a health space with thousands of dimensions. Remarkably, common themes persist that predict the evolution of species as readily as the orbits of planets or the collapse of stars into black holes. This book tells the history of spaces of expanding dimension and increasing abstraction and how they continue today to give new insight into the physics of complex systems. Galileo published the first modern law of motion, the Law of Fall, that was ideal and simple, laying the foundation upon which Newton built the first theory of dynamics. Early in the twentieth century, geometry became the cause of motion rather than the result when Einstein envisioned the fabric of space-time warped by mass and energy, forcing light rays to bend past the Sun. Possibly more radical was Feynman's dilemma of quantum particles taking all paths at once — setting the stage for the modern fields of quantum field theory and quantum computing. Yet as concepts of motion have evolved, one thing has remained constant, the need to track ever more complex changes and to capture their essence, to find patterns in the chaos as we try to predict and control our world.

Shadowlands

Download Shadowlands PDF Online Free

Author :
Publisher : Universal-Publishers
ISBN 13 : 9781581126457
Total Pages : 256 pages
Book Rating : 4.1/5 (264 download)

DOWNLOAD NOW!


Book Synopsis Shadowlands by : Robert Foot

Download or read book Shadowlands written by Robert Foot and published by Universal-Publishers. This book was released on 2002 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a revolutionary new theory, Dr. Robert Foot of the University of Melbourne argues that meteorites composed of mirror matter could impact with the Earth without leaving any ordinary fragments. Indeed, the theory seems to provide a simple explanation for the puzzling Tunguska event--the blast which destroyed a huge area of Siberian forest in 1908. While scientists have attributed this explosion to an ordinary meteorite, no traces of such an object have ever been found. Moreover, there are frequent smaller such events, occurring on a yearly basis, which are even more puzzling. Foot's new book lays clear the scientific case for mirror matter. It describes the fascinating evidence for its existence including, astronomical observations suggesting that most of our galaxy is made from a new form of matter--dark matter. It explains puzzling Jupiter sized planets only a few million miles from their host star, and the mysterious slowing down of spacecraft in our solar system. Remarkably, it is also possible that Pluto might even be a mirror world, which would explain various anomalous features of its orbit. Perhaps the most important consequence of all this--if true--is the possibility of actually extracting the mirror matter from the Tunguska impact site and other such sites on earth. Invisible asteroids and other cosmic bodies made of a new form of matter may pose a threat to Earth, agrees a noted Australian physicist. But the mirror matter idea has not attracted a huge following among physicists. In a recent UPI article, Howard Georgi of Harvard University says, "Foot's ideas have not attracted a huge following in the community that cares about these things, perhaps because the problems they solve, while interesting, are not the most critical puzzles that we are wrestling with." Nevertheless, mirror matter, if it exists, would be a completely new type of material with a potentially huge commercial value. Its scientific value would be of no less importance. FROM THE BACK COVER Nearly 50 years ago it was discovered that the fundamental particles, such as the electron and proton, have `left-handed' interactions; they do not respect mirror symmetry. This experimental fact motivates the idea that a set of `mirror particles' exist. The left-handedness of the ordinary particles can then be balanced by the right-handedness of the mirror particles. In this way mirror reflection symmetry can exist but requires something profoundly new. It requires the existence of a completely new form of matter called `mirror matter'. Remarkably the mirror matter theory is capable of simply explaining a large number of contemporary puzzles in astrophysics and particle physics. The evidence ranges from observations suggesting that most of the matter in the Universe is invisible, to unexpected properties of ghostly particles called `neutrinos'. This book explains this fascinating theory and its evidence at a level accessible to the non-specialist.

Yet Another Introduction to Dark Matter

Download Yet Another Introduction to Dark Matter PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3030162346
Total Pages : 183 pages
Book Rating : 4.0/5 (31 download)

DOWNLOAD NOW!


Book Synopsis Yet Another Introduction to Dark Matter by : Martin Bauer

Download or read book Yet Another Introduction to Dark Matter written by Martin Bauer and published by Springer. This book was released on 2019-06-11 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark matter is a frequently discussed topic in contemporary particle physics. Written strictly in the language of particle physics and quantum field theory, these course-based lecture notes focus on a set of standard calculations that students need in order to understand weakly interacting dark matter candidates. After introducing some general features of these dark matter agents and their main competitors, the Higgs portal scalar and supersymmetric neutralinos are introduced as our default models. In turn, this serves as a basis for exploring four experimental aspects: the dark matter relic density extracted from the cosmic microwave background; indirect detection including the Fermi galactic center excess; direct detection; and collider searches. Alternative approaches, like an effective theory of dark matter and simplified models, naturally follow from the discussions of these four experimental directions.