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The Beyond Einstein program aims to answer these questions. Beyond Einstein fascinates the American public and compels the attention of the news. are beyond the scope of this thesis, and we refer the reader to the reviews . theory of gravity we will be modifying: Einstein's general relativity. The Philosophy of Psychology What is the relationship between common-sense, or 'folk', psychology and contemporary s.

Beyond Einstein Pdf

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Uploaded by: SEEMA 1. Beyond Einstein: non-local physics Einstein's Special and General Relativity theories, have proven to be very useful in the several. PDF | This article provides a review of the latest experimental results in quantum physics and astrophysics, discussing their repercussions on the advanced. Beyond Einstein takes readers on an exciting excursion into the discoveries that have led scientists to the brightest new prospect in theoretical.

Cadenza LISA will open a new window on the Universe through the study of low-frequency gravitational waves. The laser light received from the two distant spacecraft is combined with the light from the local lasers. LISA will have greatest sensitivity to gravitational waves of periods of to seconds.

Combining the signals from all the pairs of spacecraft will permit detection of both of the two polarizations of gravitational waves of the waves. At the heart of each spacecraft are two free-flying reference masses for the detection of gravitational waves.

The Constellation-X mission has been in formulation since with a focused technology development program. Recent technology investments provide a clear path for future efforts that would support launches as early as These two elements. Sources will be distinguished by studying the time evolution of their waveforms. Micronewton thrusters will maintain drag-free control of the spacecraft about the proof masses.

In one year of observation. Two cm telescopes direct the beams from two cavity-stabilized lasers toward the other two spacecraft. LISA will simultaneously observe a wide variety of sources from all directions in the sky. The major science objectives of LISA include: No other signal survives from that era. LISA will be the first instrument capable of detecting gravitational waves from already cataloged objects several binary stars. None of these can be detected by ground-based detectors.

Their orbital trajectories determine the full spacetime geometry down to the event horizon. Sources of gravitational waves that LISA should detect include all the thousands of compact binaries in our own Galaxy. LISA may also detect violent events in the early Universe. The desire for precise measurements of these weak signals set the sensitivity goals for LISA. LISA measures periods between 10 seconds and a few hours.

This will allow detailed observations of information-rich. This will probe energy and length scales characteristic of the Universe seconds after the Big Bang. Although they run on general principles similar to LISA. LIGO and other ground-based laser-interferometer gravitational wave observatories are beginning operation.

LISA will also detect or strongly constrain the rate of mergers of intermediate mass or seed black holes. LISA will be able to observe for a year or more any merger of supermassive black holes in merging galaxies. For example. LIGO will hear the final few minutes of radiation from merging black hole remnants of ordinary binary stars about ten or more times the mass of the Sun. There are several plausible strategies.

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Probing dark energy requires measuring precisely how the expansion rate of the Universe is. Einstein Probes Dark Energy Probe The nature of the mysterious dark energy that dominates our Universe is one of the newest and most important questions facing cosmology and fundamental physics today. With technological advances. Because they are on the ground. As a result they are optimized to detect waves of much shorter periods than LISA.

The Department of Energy has begun such development and is an interested partner in such a mission. The sensitivity would be required to allow source detection down to 29th magnitude at 1 micron. Considerable technology investment would be necessary to develop reliable detector arrays of such large format. If the Dark Energy Probe shows that the dark energy density varies with time.

We now know that his constant is equivalent to an energy density of the vacuum. We can use our current understanding of how quantum mechanics and gravity join to estimate what the energy density of that vacuum should be. Pinning down the precise value will both verify the existence of this mysterious component beyond any doubt and.

More dramatic alternative candidates for dark energy include dynamically evolving fields or even a breakdown of the general theory of relativity. A mission of this type could search for large numbers of Type Ia supernovae in the redshift range 0.

To decide which is right. An experimental measurement of a small but nonzero cosmological constant would dramatically influence the search for a quantum theory of gravity. HgCdTe collectively providing multicolor coverage over the range 0. The result is times larger than the experimental limits! Our understanding is clearly incomplete. This could be accomplished by repeatedly scanning a limited region of sky about 10 square degrees.

The focal plane would consist of billion-pixel arrays of CCDs and near-infrared detectors e. If the Dark Energy Probe shows that the dark energy density is constant in time.

Many of the Beyond Einstein missions require that they be located far from Earth. This will provide the most precise test yet of the gravitational theory for the origin of galaxies and structure in our Universe.

Both density fluctuations and gravitons gravitational wave quanta produced in the very early Universe combined to determine this pattern. One promising approach would use a 2-meter cooled telescope located at L2. Just before the Universe became neutral. This generated a pattern of polarization related to the temperature fluctuations of the CMB. Constellation-X and the Inflation Probe require thermal control and will orbit around L2.

Temperature anisotropy studies. The Inflation Probe will: The L2 point is located approximately 1. It will also test physics at energies that are currently inaccessible by any other means.

Each pixel must also be observed simultaneously from 50— GHz to allow astrophysical foregrounds to be subtracted.

Did massive black holes form when galaxies formed? Did they slowly grow later? How fast are they still growing? We need a census of accreting black holes to find out. The detectors that will fly on Planck are already close to fundamental quantum limits.

This will test theories of the very early Universe. The signals from inflation are likely to be mixed with confusing foregrounds and effects from gravitational lensing. The optical appearance of a galaxy usually does not advertise the presence of a black hole. Even the three closest supermassive black holes now swallowing gas are hidden in galaxies that otherwise appear normal.

The angular resolution of the maps must be a few arcminutes to allow the true gravitational wave signal to be distinguished from secondary sources of polarized CMB signals. Yet these black holes have had a dramatic effect on the formation and evolution of galaxies— and even life. This simulation shows the circular patterns gravitational waves as long as the Universe leave in the polarization of the cosmic microwave background.

The Black Hole Finder Probe will enable a range of studies of black holes and the extremes of astrophysics: The required angular resolution is about 3— 5 arcmin. It can identify the most luminous obscured black holes at larger redshifts to estimate the growth rate of massive black holes.

To perform a reliable census. X-rays can best be distinguished from emission from stars. A veil of dust and gas currently hides most accreting black holes from our view. It will perform the first all-sky imaging census of accreting black holes: It will complement LISA.

Highenergy X-rays. Follow-up studies with Constellation-X and eventually the Black Hole Imager will measure fundamental black hole properties spin. Besides the familiar stars. The faintest survey sources would have 1 arcmin centroids. Of these. To penetrate gas and dust. Like electromagnetic waves. This could give us a direct view of the creation of space and time and.

In between. They will also enable even finer measurements of the structure of spacetime around black holes than will be possible with LISA. To reduce the risks.

The ultimate goal of the Big Bang Observer is the direct detection of these gravitational waves. At the shorter periods at which ground-based gravitational wave detectors must operate. The hydrogen and helium around us formed when the Universe was a few minutes old. Thus they carry information to us undisturbed from the earliest moments of the Universe. The radio waves of the cosmic microwave background escaped and began their journey to us when the Universe was Gravitational waves escaped on a journey to us when the Universe was less than seconds old.

At longer periods. These are believed to form from the first massive stars born in our Universe. In this frequency range. Yet the signal from the quantum foam of the early Universe is still within reach.

Understanding the expansion history of the Universe at the moments when quantum foam was becoming our familiar space and time requires measuring the gravitational wave relics from this era at least two widely spaced frequencies. The Inflation Probe will search for the effects of waves with periods of billions of years. The goal of the Black Hole Imager mission will be to image directly matter falling into a black hole, with resolution comparable to the scale of the event horizon.

An angular resolution of 0. This resolution can be achieved at high radio frequencies and at X-ray wavelengths. A simple image, while exciting in concept, is not sufficient to study the dynamics of the inner regions. To better disentangle the complicated dynamics near the black hole will require spectroscopy to map the speed as well as position of gas as it nears the event horizon.

This will require spectroscopically resolved imaging at the wavelengths of X-ray lines. The science objectives for a black hole imaging mission are: Constellation-X takes a first step by demonstrating time-resolved spectroscopy of relativistically broadened X-ray lines but without the imaging capability of Black Hole Imager. The underlying mechanisms by which gas swirling into black holes loses energy are not well understood.

A direct image of the inner disk could reveal the details of this process. The ultimate irony of black hole accretion is that rather than swallowing everything, somehow many black holes manage to generate relativistic jets, by mechanisms that remain a mystery.

Imaging and spectroscopy will also provide direct tests of models that predict that magnetic fields extract energy from the black hole itself to power these jets. A simulated Black Hole Imager view of an accretion disk around a black hole.

The bending of light rays by the black hole makes the back side of the disk appear raised. Your feet arrive last. The Beyond Einstein program cannot succeed without investment in key enabling technologies for each mission. No mission can go into full flight development before it has achieved the appropriate level of technical readiness.

This requires a well-balanced technology program, in which both near- and long-term mission needs are addressed. Technology development for Beyond Einstein must be coordinated with other Space Science themes to identify cost sharing opportunities. Technology from early missions must be extended for later, more demanding missions. Scientists, the end-users of the technology, must be involved at all stages to ensure that mission requirements are met. Einstein Great Observatory Technologies Both Einstein Great Observatory missions have been under study for several years and have detailed technology roadmaps in place.

We highlight key elements below:. Constellation-X Constellation-X will provide X-ray spectral imaging of unprecedented sensitivity to determine the fate of matter as it falls into black holes, and map hot gas and dark matter to determine how the Universe evolved largescale structures.

Lightweight, grazing incidence X-ray optics. Each of the four identical Constellation-X spacecraft will carry two sets of telescopes: Both incorporate highly nested, grazingincidence X-ray mirror arrays, which must simultaneously meet tight angular resolution, effective area, and mass constraints. X-ray calorimeter arrays. Two technologies are being developed in parallel: Both have made substantial progress toward the required energy resolution of 2 eV.

Multiple approaches to fabrication of high-quality arrays and multiplexed readout amplifiers are under development. Long-lived 50mK coolers. Constellation-X requires reliable longlife first stage coolers operating at 5—10 K. The ultimate detector temperature of 50 mK will be reached by one of several adiabatic demagnetization refrigerator technologies currently under study.

Grazing incidence reflection gratings. Reflection gratings dispersed onto CCDs provide imaging spectroscopy in the 0.

For Constellation-X, improvements to reduce weight and in To measure the properties of merging pairs of supermassive black holes requires good sensitivity down at least to Hz.

The measurement of the relative motion of these dragfree masses allows us to sense the passage of gravitational waves through the Solar System. It consists of a triangle of reference masses in solar orbit connected by a precision metrology system. At hard X-ray energies. A prototype mirror segment for Constellation-X being separated from the replication mandrel. The key technologies are those to 1 minimize external disturbances of the reference masses.

Novel event-driven CCDs have recently been developed that provide significant improvements in performance and robustness. Key requirements have been demonstrated but work is continuing on extending the response at low energies and reducing the effects of electron trapping. Solid-state hard X-ray imaging detectors. To use the capture of compact objects to map spacetime outside of supermassive black holes sets the sensitivity requirements at wave frequencies of — Hz.

Changes in the 5 X km test mass spacing must be measured to m. This will require an Einstein Probe technology development Gravitational reference units of the kind shown inset and here undergoing testing are at the heart of the LISA mission. Correction signals are sent to the thrusters by gravitational reference units GRUs.

Laser Measurement System. Technology Development for the Einstein Probes The Einstein Probe mission concepts will be competed in order to choose the best scientific and technical approaches to their goals. But orbital dynamics lead to changes in spacecraft spacing that can create a fringe rate as large as 15 MHz. This program will be an important validation of the critical disturbance reduction system components.

Readiness must be evaluated before each competition. All of the measurements planned for the three Einstein probe missions are technically challenging. Micronewton thrusters keep the spacecraft precisely centered about the masses. That requirement can be met by existing lasers and detection systems.

System Verification. This imposes stringent requirements on laser frequency stability. Disturbance Reduction System. The very large detector arrays are a serious challenge: Some particular mission concepts are already being studied for each of the Probe science areas. The U. This may sound small. Even for optimistic models. The primary mirror must have much lower cost and mass-per-unit-area and be developed faster than the HST primary.

If relativity were not taken into account. Inflation Probe The Inflation Probe aims to detect signatures of gravitational waves with wavelengths comparable to the size of the Universe produced by quantum fluctuations of spacetime during inflation. If relativity were not accounted for. At infrared wavelengths. At optical wavelengths. A mission capable of such observations requires a wide field of view telescope with about a 2-meter diameter mirror. It will do this by measuring the weak imprint they leave on the polarization of the cosmic microwave background.

A portable GPS receiver determines position by simultaneously receiving signals from atomic clocks on the GPS satellites. Global Positioning System. This program should be provided as early as possible to allow all of the promising approaches to each mission to be thoroughly vetted. Below we discuss the technology development required for these candidate concepts. The whole system would be utterly worthless for navigation!

All of these elements require substantial technology development.

The Cosmic Quest for the Theory of the Universe

It is an order of magnitude weaker than the polarization components pro To separate these foreground sources requires extraordinary sensitivity and angular resolution. A CdZnTe detector array seems the most likely candidate. To provide sufficient sensitivity. Although detailed designs for successor missions would be premature. The sensitivity required is roughly 20— times that of the HFI focal plane detector on Planck. Since reflective optics provide very limited fields of view at these high energies..

Other technical challenges include the need for cold optics at low cost and mK detector operating temperatures with very stable temperature control.

One possible solution consists of four separate interferometers. Source-by-source removal of this foreground is practical at wave periods of 0. Big Bang Observer The ultimate goal of a Big Bang Observer is to directly observe gravitational waves with sufficient sensitivity to observe the background due to the quantum fluctuations during inflation. Achieving such a vast increase in sensitivity requires significant advances: Such a survey instrument would need to be sensitive over an energy range of about 10— keV.

This must be accomplished in the face of a strong foreground of gravitational waves produced by all the binary stars and black holes in the Universe. Other technology problems arise in the areas of mask fabrication and data acquisition at high trigger rates. Here a W laser scalable to 30 kW is shown under test. Such a configuration imposes many technical challenges. This will require advances in mirror fabrication. Acceleration Noise. A significant improvement in strain sensitivity. This gravitational wave frequency band will not have been previously explored.

To provide scientific guidance and to reduce the risk associated with making such large technical advances in one step. A gravitational reference sensor with acceleration noise performance times lower than that planned for LISA is required. Black Hole Imager The goal of the Black Hole Imager is to enable direct imaging of the distribution and motion of matter in the highly distorted spacetime near the event horizon of a black hole.

An X-ray interferometer is naturally matched to this task. An X-ray interferometer with 0. Strain Sensitivity. At wavelengths near 1 nm. This will require angular resolution better than 0. This means that separate spacecraft are needed with highly controlled formation flying. Nominal requirements are: The Black Hole Imager makes use of X-ray interference lower left.

An advanced form of gyroscope may be needed. To reduce the risks associated with making such large technical advances as these in one step. Mirror figuring. Though grazing incidence relaxes the required surface figure accuracy. Sensing and controlling the orientation of the line joining the centers of the reflector and detector spacecraft is probably the greatest technology challenge.

Theoretical studies include conceptual and analytical theory. That survey recommended that support for theory be explicitly funded as part of each mission funding line. Theoretical studies of early Universe cosmology. Rigorous modeling is an important factor in reducing mission risk and evaluating competing mission strategies. Chapter 4. Studies and simulations of signal extraction in the presence of multiple.

Theoretical studies of Type Ia supernovae and other candidate systems for calibrating cosmic distances. Beyond Einstein explores to the boundaries of foundational knowledge as well as to the boundaries of spacetime. Some examples of necessary theoretical studies supporting Beyond Einstein are: Comprehensive simulation of black hole environments. Early Universe cosmology and phenomenology of quantum gravity. Theoretical work combining anticipated new results from particle theory and experiment with cosmology will be important to optimize the probe to test theories of dark energy.

Models of relativistic hydrodynamic flows in accretion disks. Similar foundational studies are needed for other candidate techniques for the Dark Energy Probe. This is required on the shape of the Universe from observaboth as a calibrating set for the hightions of the cosmic microwave background. The Inflation Probe. Detector technology for COBE. Supporting Ground-Based Research and Analysis Beyond Einstein missions also require specialized supporting ground-based programs.

If Type Ia supernovae are employed. In the same way. Ground-based cosmic microwave background polarization experiments will be essential preparation for the Inflation Probe. In the case of the Einstein Probes. Whatever technique is adopted. Programs supporting ground-based studies of this type are already underway with funding from the National Science Foundation and the Department of Energy.

As in the case of theory. Its quest to investigate the Big Bang. This latter goal. The missions and probes in the Beyond Einstein theme offer unique educational opportunities.

Chapter 5. The missions and research programs in Beyond Einstein will bring significant resources to this educational challenge. In addition. Education and Public Outreach Education. Students yearn for a deeper Another crucial area of opportunity is technology education. The fantastic requirements of a mission like LISA—which will measure an object being jostled by less than the width of an atom—provoke the kind of excitement and questioning that draws young people into science and technology in the first place.

Many states now require technology education in middle school.

New results from MAP. These are necessary topics for the education community as they are included in the National Science Education Standards. The Beyond Einstein missions will fill many of the needs for materials about the Big Bang.

It matches what scientists regard as fundamental results with the appropriate education curriculum in a manner that is more specific than those embodied in the standards.

The missions of Beyond Einstein address the space science content in the origin of the Universe. Journey to the Edge of Space and Time. Education and public outreach programs in the past have seen great success in telling the human side of planning. I am a homeschooler and this is so comprehensive. Thanks to an efficient network of partnerships throughout the education and outreach communities.

Outreach programs for the Beyond Einstein theme will build on these existing partnerships and programs. Imagine the Universe!. Educational products and programs on the science themes of Beyond Einstein are expected to be extremely popular.

Either directly or indirectly. Special emphasis is placed on the pre-college years. We know that the public clamors to be involved in this story. The Starchild Web site for elementary students was one of the first winners of the Webby award for Education. Links to teachers will be established early in the Beyond Einstein program so that the educational component can grow with the program. The pioneering missions in Beyond Einstein offer opportunities to see the impact of dealing with profound questions on those who work toward the answers.

OSS products and programs now reach virtually every avenue of public interest. Beyond Einstein missions will weave an ongoing story that is considered one of the most compelling in all science—a story that will form the raw material for museum exhibits.

Chandra X-ray Observatory image of the gas remnant of a supernova explosion. Most of your body mass comes from elements created in stars. Cassiopeia A. Understand the development of structure in the Universe. Research Focus Area 8. Science Objective 5. Discover how gas flows in disks and how cosmic jets are formed. Research Focus Area Discover how the interplay of baryons. Research Focus Area 9. Determine how. Explore the cycles of matter and energy in the evolving Universe.

Understand how matter. Science Objective 4. Identify the sources of gamma-ray bursts and cosmic rays. Explore the behavior of matter in extreme astrophysical environments. Eta Carinae suffered a giant outburst about years ago and now returns processed material to the interstellar medium. The Universe is governed by cycles of matter and energy. A huge. Fowler [Nobel Prize.

From gas to stars and back again. To understand how matter and energy are exchanged between stars and the interstellar medium. It is illuminated with the soft glow of nascent and quiescent stars.

The aim of the SEU theme is to understand these cycles and how they created the conditions for our own existence. The SEU portfolio includes missions that have revolutionized our understanding of the web of cycles of matter and energy in the Universe. Even as the Universe relentlessly expands. To understand the structure and evolution of the Universe.

Chapter 6. The Chandra X-ray Observatory has been notable in this regard. Interdependent cycles of matter and energy determine the contents of the Universe. But to unravel the interlinked cycles. The missions of Beyond Einstein can address some of the goals of the Cycles of Matter and Energy program. Our task includes uncovering the processes that lead to the formation of galaxies and their dark matter halos.

Beyond Einstein

The accumulated products of these events become the material for new stars that form in the densest interstellar regions. What We Have Learned The cycles that we seek to understand are driven by stars and galaxies. Bringing it all Together These stars congregate. Massive stars create new elements—oxygen. As they run out of hydrogen fuel.

Stars of later generations. The SEU theme is committed to mapping the processes by which these stellar factories build up the Universe.


Lower-mass stars evolve more sedately. To explain this rich variety. We know that when the Universe was a much younger and more violent place.

Gaseous filaments at the top of a hot bubble of gas are being expelled into intergalactic space. SEU missions will trace their evolution from their origins in the early Universe to the intricate systems we find today. Before describing how we plan to proceed.

Engines of Change in an Evolving Universe Stars are the factories for new elements in the Universe and. The oldest of these stars show us that our Galaxy once lacked the heavy elements out of which planets and people are made. The signposts of this process are the quasars Fountains of new elements spraying into the Universe. Our Earth. For a star. Different parts of these cycles produce radiation of different wavelengths. If the night were void of stars. But we can do this in at least three ways.

We can study nearby galaxies still under construction today. Even relatively quiet galaxies like our own have massive black holes lurking at their centers. Glimmers of secrets through the murk. The center of this galaxy is clearly revealed at infrared wavelengths. On Earth. And we can use powerful telescopes as timemachines to see the past directly: From space. The isolation of a space satellite also allows more stable and precise pointing. What role did black holes play in the evolution of galaxies?

It is a daunting challenge to try to understand events that happened billions of years ago in faraway places. We can measure the ages of stars in nearby galaxies to reveal their history of stellar births.

The Next Steps: The Space Astronomy Imperative Space-based telescopes are uniquely suited to uncovering the cycles of matter and energy in stars and galaxies. It also allows for cooling the telescopes.

For the farthest sources. With high spectral resolution these lines can be used to trace the flows of this gas in detail. The plan for the SEU theme takes three concerted approaches—cosmic censuses. We can use these spectral lines to measure redshifts and diagnose the radiating gas. The radiation in these lines rapidly cooled the interstellar clouds. The dust absorbed light and protected subsequent stellar nurseries from the damaging effects of ultraviolet light.

Metals such as gold and The Big Bang created only the lightest two elements. So the first generation of stars formed in warm. These clouds cooled because hydrogen molecules radiated their heat—at infrared wavelengths that can only be seen from space. Supernovae bright enough to observe directly are relatively rare. Cryogenic single-dish space telescopes will provide direct measurements of these lines and.

This was a key event. Most of the line radiation that cools collapsing gas clouds is not accessible to ground-based investments such as the Atacama Large Millimeter Array ALMA. The dust hides these nurseries from optical and ultraviolet instruments but is transparent to the infrared light that the dust emits. The carbon. To understand the consequences.

Details of a distant youth. But the rapidly expanding remnants they leave behind slowly cool and mix with the surrounding interstellar medium. A cryogenic. For this reason. The first solid particles. The infrared acuity of a space-based meter far-infrared telescope small yellow circles is superimposed on a simulated JWST image of distant extragalactic targets. Submillimeter interferometers in space will eventually offer detailed images.

The larger telescope will be able to pick out newly born galaxies at the edge of the Universe. The Explosive Enrichment of Galaxies The structure and evolution of the Universe is strongly driven by stellar collapse and explosive events.

Those that last longer than about one second are most likely associated with massive stars and corecollapse supernovae. We will build telescopes that will do this. A wide-field. A color composite of the supernova remnant E X-ray blue. These elements were created by nuclear reactions inside the star and hurled into space by the supernova. Gamma-ray line telescopes will also help studies of classical novae. Ground-based and space-based optical follow-up studies will supplement these efforts.

Recent technical advances offer increased sensitivity. The Chandra X-ray Observatory image shows. The X-ray data show that this gas is rich in oxygen and neon.

While the statistics are still sparse. An advanced Compton telescope that can see the radiation from these radioactive decays can be used to study the explosion mechanisms in core-collapse supernovae. E is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. While pioneering efforts have come out of the Compton Gamma Ray Observatory.

Others may arise when a star is swallowed by a nearby black hole. Even in these smaller explosions. Radioactive elements are formed in detonation and core collapse supernovae. As a result. Studies of gamma-ray bursts GRBs have produced some of the most striking science of the last decade. Visions of new elements from a cosmic furnace. Most of the material of supernova remnants shines brightly with X-ray lines and Constellation-X will play an important role in determining their makeup: Cosmic rays provide another sample of material from the vicinity of supernova explosions.

The bursts are so bright that they can be seen even from the distant. Some gamma-ray bursts signal the death of a star and the birth of a black hole. Neutron stars offer extraordinary densities of matter and magnetic field strengths. Their physics determines how energy and matter are deposited throughout the Universe. These objects also allow observational access to extremes of density.

With a half-life of about a million years—short compared with the timescale of nucleosynthesis—the bright spots that concentrate in the inner galaxy must be contemporary sites of elemental enrichment. Neutron stars Revealing gravitational rogues inside galaxies. In this wide angle 1. Light and Wind from the Heart of the Beasts Beyond Einstein focuses on the physics of spacetime around compact objects and in the early Universe. Compact objects can be probed in many ways. Glowing embers of galactic nucleosynthesis.

Compact objects—white dwarfs. A cooling neutron star appears as a hot object in X-rays. Future telescopes will let us see nucleosynthesis happen. Unique processes. These cosmic laboratories test physics under extreme conditions that we cannot reproduce on Earth. The bright central source is probably due to a supermassive black hole in the nucleus of the galaxy.

Matter falling onto a neutron star from a binary companion also heats up and can ignite in thermonuclear explosions. Oscillations in the X-ray emission of compact objects reveal instabilities in the accretion disk and even the underlying Firing celestial beams of matter.

Diagram of AGN with warped disk. It is this vastly smaller scale that space interferometry will probe. The large improvement in spatial resolution of space radio interferometry over that from the ground allows the inner parts of nearby galactic accretion disks.

Note nonlinear scale. At right. Swirling disks of death around black holes. As the gas falls in. The gravitational energy liberated by the infall causes the central region of the disk to become fiercely luminous and it drives a jet of material outward along the polar axes of the galaxy.

The veil can be penetrated by infrared. In recent years. AGNs can be seen at very great distances. In this artist rendering. Because of their high luminosities.

These nuclear furnaces are often shrouded by the very dust and gas that provides the fuel for the beast. Quasars are active galactic nuclei AGN so bright that they outshine the surrounding galaxy. Peering into the hearts of galaxies. The evidence suggests that their radiation is produced by a supermassive black hole ingesting material from the galaxy surrounding it.

These studies will help us pin down the role black holes have played in the development of galaxies. Compact object studies reveal the activity of high-mass stars that produce the heavy elements required for life to form. Since the accretion disk is the supplier of fuel for compact objects. While it now seems to be accreting little matter. Though hidden from optical view by the disk of our Galaxy. While jets have now been observed throughout the electromagnetic spectrum.

New instruments from the Beyond Einstein program will help us study the innermost parts of the accretion disks of supermassive black holes. The full power of radio interferometry will not be realized until space-based telescopes provide longer baselines and shorter wavelengths.

A radio interferometry mission would resolve accretion disks around AGN out to almost Mpc and probe the inner disk that surrounds the closest supermassive black hole.

Did supermassive black holes form by merger of smaller ones. Accretion disks are also studied on larger scales using ground-based very long baseline interferometry VLBI. Such measurements would supplement the more complete dynamical picture provided by Constellation-X and the vision mission Black Hole Imager. Understanding how these jets are made. Constellation-X will study these galaxies in spectroscopic detail. This can map radio-emitting material in the accretion disk with a resolution over a hundred times finer than HST gets at visible wavelengths.

Such observations would help us design an eventual vision mission that could see even quiet galaxies at great distances and round out our picture of galaxy formation. Of special interest is the black hole that sits quietly at the center of our own Milky Way galaxy. Molecular maser lines would offer information about mass motions in the cooler.

As the closest massive black hole. This emission arises in the cool. We will locate the source and understand how it produces this extraordinary material. Low-resolution positron annihilation maps of the Milky Way made by the Compton Gamma-Ray Observatory reveal recognizable features from the disk and inner bulge of our Galaxy.

Large scale positron production is theoretically expected from black hole antimatter factories. They most likely arise from the detonation of a white dwarf that pulls so much mass off of a nearby companion that it collapses. Our Universe is asymmetric. We look ahead to building new low-energy gamma-ray telescopes designed specifically to search for annihilation radiation. But we cannot understand the evolution of their properties over cosmic times without modeling their nuclear burning and dynamics.

Positrons are formed by the decay of radioactive elements. By observing and modeling this radiation. These can be identified by their characteristic gamma-ray emission lines. Emission from compact sources could be highly transient.

With vastly higher spatial resolution and sensi- Detailed comparison of star formation in galaxies with active nuclei will be needed to investigate the roles that accretion disk-driven winds and point-like gravitational fields have on the formation of stars and the evolution of galaxies.

The origin of these positrons is unclear. The maps show that positrons are distributed on a Galaxy-wide scale. But they can also help us measure it! Type Ia supernovae are uniquely important in this regard because they are very bright and have roughly constant peak brightness. Such telescopes could detect all Type Ia supernovae out to at least the Virgo Group. We know that antimatter exists in the Universe.

An intensive hunt for such supernovae is under way and early results have led to the monumental realization that the expansion of our Universe is accelerating. In such an annihilation. While the search for antimatter can be conducted with cosmic-ray and gamma-ray experiments. Supernovae play a profoundly important role in the chemical enrichment of the Universe. A supernova of Type Ia can eject large quantities of newly formed radioisotopes. Visions of Annihilation Antimatter is being produced prodigiously in at least our own Galaxy.

These cosmic flash bulbs can thus be used to measure the large scale geometry of the Universe. Searching for sources of antimatter in a galactic forest. This is the highest resolution positron annihilation image available. Determining the nature of this non-baryonic dark matter is one of the central goals of modern physics and astronomy.

At top is the wealth of structure in the very center of this region as seen in three different parts of the spectrum. To keep their stars and hot gas from flying away. The Mystery of the Missing Matter According to the best cosmological models. Observing the center of our Galaxy will establish whether a burst of star formation there is responsible for driving a superwind laden with positrons and newly synthesized material. This montage illustrates our need for much more detailed images from new generation gamma ray telescopes to identify the sites and sources of antimatter in the inner galaxy.

The image of keV radiation from the Compton Gamma Ray Observatory is shown in the lower image and covers about 10 degrees of the sky around our Galactic Center.

These estimates still exceed the amount that we can actually see in stars and interstellar gas by a factor of ten. But the gravitational mass of the Universe is much larger still. We want to find this missing matter to understand why so little of it was used to build stars and galaxies. The fluctuations of the cosmic microwave background radiation are a powerful tool for assessing the total mass content of the Universe.

This polarization will reveal gravitational lensing by intervening matter. An efficient way to locate missing baryonic matter in the darkness of intergalactic space is to look for absorption of light from distant quasars. Making missing matter appear.

If the gas is hot and chemically enriched. By mapping this hot gas. A false-color X-ray image of the hot gas blue cloud taken by ROSAT is superimposed here on an optical picture of the galaxy group. The superstring theory. If correct, this means that the protons and neutrons in all matter, everything from our bodies to the farthest star. Nobody Ims seen these strings because they arc much too small to be Sllper. They are about billion billion times smaller than a proton.

According to the superstring theory, our world only appears to be made of point particles, because our measuring devices are too crude to see these tiny strings. At lirst it seems strange that such a simple concept-replacing point particles with strings-can explain the rieh diversity of partides and Drees which are created by the exchange of particles in nature. The superstring theory, however, is so elegant and comprehensive that it is able to explain simply why there can be billions upon billions of different types of particles and substances in the universe, each with astonishingly diverse characteristics.

Thc superstring theory can produce a coherent and all-inclusive picture of nature similar to the way a violin string can be used to "unite" all the musical tones and rules of harmony. Historically, the laws of music were formulated only after thousands of years of trialand-clTor investigation of different musical sounds. Today, these diverse rules can be derived easily from a single picture-that is, a stling that can resonate with different frequencies, each orie creating a separate tone of the musical scale.

The tones created by the vibrating string, such as C or B flat, are not in themselves any more fundamental than any other tone. What is fundamental, however. Knowing the physics of a violin string, therefore, gives us a comprehensive theory of musical tones and allows us to predict new harmonies and chords. The gravitational intcraction. Higher excitations of the string create different forms of matter.

From the point of view of the superstring theory. All particles are just different vibratory resonances of vibrating strings. Thus, a single framework-the superstring theory-can in principle explain why the universe is populated with such a rich diversity of particles and atoms.

The answer to the ancient question "What is malter'! The "music" created by the string is matter itscl f. But the fundamental reason why the world's physicists are so excited by this new tht:ory is that it appears to solve perhaps the most important scientific problem of the century: namely, how to unite the four forces of nature into one comprehensive theory.

At the center of this upheaval is the realization that the lour fundamental forces governing our universe are actually different manifestations of a single unifying force, governed by the superstring. Electricity is a force because it can make our hair stand on end. Over the last two thousand years, we grddually have realized that there arc four fundamental forces: gravity, electromagnetism light.

Other forces identified by the ancients, such as lire and wind, can be explained in terms or the four forces. One of the great scientific pllZl:les of our universe. For the past fifty years. To help you appreciate the excitement that the superstring theory is generating among physicists. Gravity is an attractive force that binds together the solar system. In our universe, gravity is the dominant lorce that extends trillions upon trillions of miles, out to the farthest stars; this force, which causes an apple to fall to the ground and keeps our feet on the floor, is the same torce that guides the galaxies in their motions throughout the universe.

The electromagnetic forcc holds together the atol It makes the electrons with negative charge orbit around the positively charged nucleus of the atom. Because the electromagnetic force determines the structure of the orbits of the electrons, it also governs the laws of chemistry.

S"perstr;ngs: A Theory of Everything? By rubbing a comb, for example, it is possible to pick up scraps of paper from a table. The electromagnetic force counteracts the downward force of gravity and dominates the other forces down to.

Perhaps the most familiar form of the electromagnetic force is light. When the atom is disturbed, the motion of the electrons around the nucleus becomes irregular.

This is the purest form of electromagnetic radiation, in the form of X rays, radar, microwave, or light. Radio and tclevision are simply different forms of the electromagnetic force.

Wlthm the nucleus of the atom, the electromab'lletic force is overpowered by the weak and strong nuclear forces. The strong force, for example, is responsible for binding together the protons and neutrons in the nucleus.

In any nucleus, all the protons arc positively charged. Left to themselves. The strong force, therefore, overcomes the repulsive force between the protons. Roughly speaking, only a few elements can maintain the delicate balance between the strong force which tends to hold the nucleus together and the repulsive electric loree which tends to rip apart the nucleus , which helps to explain why there are only about one hundred known elements in nature.

Should a nucleus contain more than about a hundred protons, even the strong nuclear force would have difficulty containing the repulsive electric force between them. When the strong nuelear force is unleashed, the effect can be catastrophic. For example. Pound for pound.

Indeed, the strong force can yield significantly more energy than a chemical explosive. The strong force also explains the reason why stars shine.

A star is hasically a huge nuclear furnace in which the strong force within the nueleus is unleashed. If the sun's energy, for example, were created hy burning coal instead of nuclear fuel, only a minuscule fraction of the sun's light would be produced. The sun would rapidly fizzle and 8 A Theory of the Universe turn into a cinder. Without sunlight, the earth would turn cold and life on it would eventually die. Without the strong force, therefore. If the strong force were the only force at work inside the nucleus, then most nuclei would be stable.

However, we know from experience that certain nuclei such as uranium, with ninety-two protons are so massive that they automatically break apart, releasing smaller fragments and debris, which we call radioactivity.

In these elements the nucleus is unstable and disintegrates. Therefore, yet another, weaker force must be at work, one that governs radioactivity and is responsible for the disintegration of very heavy nuclei.

This is the weak force. The weak force is so fleeting and ephemeral that we do not experience it directly in our lives. However, we feel its indirect effects. When a Geiger counter is placed next to a piece of uranium, the clicks that we hear measure the radioactivity of the nuclei, which is caused by the weak force. The energy released by the weak force can also be used to create heat.

For example, the intense heat found in the interior of the earth is partially caused by the decay of radioactive elements deep in the earth's core.

This tremendous heat, in tum, can erupt in volcanic fury ifit reaches the earth's surface. Similarly, the heat released by the core of a nuclear power plant, which can generate enough electricity to light up a city, also is caused by the weak force as well as the strong force.

Without these four forces, life would be unimaginable: The atoms of our bodies would disintegrate, the sun would burst, and the atomic fires lighting the stars and galaxy would be snuffed out.

The idea of forces, thcreforc, is an old and familiar one, dating back at least to Isaac Newton. What is new is the idea that these forces are nothing but different manifestations of a single force. Everyday experience demonstr,ltes the fact that an object can manifest itself in a variety of forms.

Take a glass of water and heat it until it boils and turns into steam. Water, normally a liquid, can turn into steam, a gas, with properties quite unlike any liquid. Now frecze the glass of water into ice.

By withdrawing heat. But it is still water- Superstrings: A Theory of Everything? Another, more dramatic example is the fact that a rock can turn into light. Under specific conditions, a piece of rock can turn into vast quantities of energy, especially if that rock is uranium, and the energy manifests itself in an atomic bomb.

Matter, then, can manifest itself in two forms either as a material object uranium or as energy radiation. In much the same way, scientists have realized over the past hundred years that electricity and magnetism are manifestations of the same force. Only within the last twenty-five years, however, have scientists understood that even the weak force can be treated as a manifestation of the same force. The Nobel Prize in was awarded to three physicists Steven Weinberg, Sheldon Glashow, and Abdus Salam who showed how to unite the weak and the electromagnetic forces into one force, called the "electro-weak" force.

Similarly, physicists now believe that another theory called the GUT, or "grand unified theory" may unite the electro-weak force with the strong interactions.

But the final torce gravity has long eluded physicists. In fact, gravity is so unlike the other forces that, for the past sixty years, scientists have despaired of uniting it with the others.

In some sense, these two theories are opposites: While quantum mechanics is devoted to the world of the very small such as atoms, molecules, protons, and neutrons relativity governs the physics of the very large, on the cosmic scale of stars and galaxies.

To physicists, one of the great puzzles of this century has been Ihat these two theories, from which we can in principle derive the sum total of human knowledge of our physical universe, should be HI A Theory of the Universe so incompatible. In fact, merging quantum mechanics with general relativity has defied all attempts by the world's greatest minds in this century. Even Albert Einstein spent the last three decades of his life on a futile search for a unifying theory that would include gravity and light.

Each of these two theories, in its particular domain, has scored spectacular successes. Quantum mechanics, for example, has no rival in explaining the secrets of the atom. Quantum mechanics has unraveled the secrets of nuclear physics. In fact, the theory is so powertul that, if we had enough time, we could predict all the properties of the chemical elements by computer, without ever having to enter a laboratory.

However, although quantum mechanics has been undeniably successful in explaining the world of the atom, the theory fails when trying to describe the gravitational force. On the other hand, general relativity has scored brilliant successes in its own domain: the cosmic scale of galaxies.

The black hole, which physicists believe is the ultimate state of a massive. General relativity also predicts that the universe originally started in a Big Bang that sent the galaxies hurtling away from one another at enormous speeds.

The theory of general relativity, however, cannot explain the behavior of atoms and molecules. It's as if nature created someone with two hands, with the right hand looking entirely different and functioning totally independently from the left hand.Eta Carinae suffered a giant outburst about years ago and now returns processed material to the interstellar medium.

He added. Of these. International participation is a key feature of Beyond Einstein. To describe everything about an isolated black hole. This energy transformed into the richly complex matter of which we and all we touch are made. We publish prepublications to facilitate timely access to the committee's findings.

If an eBook is available, you'll see the option to purchase it on the book page. Constellation-X and the Einstein Probes have attracted international interest that will be realized when the instruments are competitively selected.

LUCIUS from North Carolina
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