PLato said,"Look to the perfection of the heavens for truth," while Aristotle said "look around you at what is, if you would know the truth" To Remember: Eskesthai
With the discovery of sound waves in the CMB, we have entered a new era of precision cosmology in which we can begin to talk with certainty about the origin of structure and the content of matter and energy in the universe-Wayne Hu
Our aim is to make "spacetime" a relevant concept in your understanding of the universe, to make "gyroscopes" a recognizable tool in the technology of your world, and to illustrate how even the most advanced science missions rest on basic physics concepts understandable by all of us.
Learn more about Gravity Probe B:
Spacecraft propulsion is used to change the velocity of spacecraft and artificial satellites, or in short, to provide delta-v. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. Most spacecraft today are propelled by heating the reaction mass and allowing it to flow out the back of the vehicle. This sort of engine is called a rocket engine.
In addition, a variety of hypothetical propulsion techniques have been considered that would require entirely new principles of physics to realize. To date, such methods are highly speculative and include
The term breakthrough propulsion refers to concepts like space drives and faster-than-light travel, the kind of breakthroughs that would make interstellar travel practical.
For a general explanation of the challenges and approaches of interstellar flight, please visit the companion website: Warp Drive: When? The Warp-When site is written for the general public and uses icons of science fiction to help convey such notions. This website, on the other hand, is intended for scientists and engineers.
A black hole is an object so massive that even light cannot escape from it. This requires the idea of a gravitational mass for a photon, which then allows the calculation of an escape energy for an object of that mass. When the escape energy is equal to the photon energy, the implication is that the object is a "black hole".
There’s a place from which nothing escapes, not even light, where time and space literally come to end. It’s at this point, inside this fantastic riddle, that black holes exert their sway over the cosmos … and our imaginations.
Special Lagrangian geometry in particular was seen to be related to another String Theory inspired phenomenon, "Mirror Symmetry". Strominger, Yau and Zaslow conjectured that mirror symmetry could be explained by studying moduli spaces arising from special Lagrangian geometry.Dr. Mark Haskins
Hawking radiation owes its existence to the weirdness of the quantum world, in which pairs of virtual particles pop up out of empty space, annihilate each other and disappear. Around a black hole, virtual particles and anti-particles can be separated by the event horizon. Unable to annihilate, they become real. The properties of each pair are linked, or entangled. What happens to one affects the other, even if one is inside the black hole.
The Pierre Auger Observatory in Malargue, Argentina, is a multinational collaboration of physicists trying to detect powerful cosmic rays from outer space. The energy of the particles here is above 1019eV, or over a million times more powerful than the most energetic particles in any human-made accelerator. No-one knows where these rays come from.
Such cosmic rays are very rare, hitting an area the size of a football field once every 10 000 years. This means you need an enormous 'net' to catch these mysterious ultra high energy particles. The Auger project will have, when completed, about 1600 detectors.
Time is of your own making;
its clock ticks in your head.
The moment you stop thought
time too stops dead. Angelus Silesius
Two main difficulties arise from Plato's view of Transmigration. First, Plato says that we have knowledge of universals because of the experiences of our souls in past lives. However, whence comes the knowledge of the first soul? In purely Platonic theory, it must have had no knowledge at all, and hence Plato's concept of transmigration as the basis for innate knowledge fails. A second difficulty lies in explaining the varying, and especially the apparently increasing number of incarnated souls over history.
Warp Drives", "Hyperspace Drives", or any other term for Faster-than-light travel is at the level of speculation, with some facets edging into the realm of science. We are at the point where we know what we do know and know what we don’t, but do not know for sure if faster than light travel is possible.
The bad news is that the bulk of scientific knowledge that we have accumulated to date concludes that faster than light travel is impossible. This is an artifact of Einstein’s Special Theory of Relativity. Yes, there are some other perspectives; tachyons, wormholes, inflationary universe, spacetime warping, quantum paradoxes...ideas that are in credible scientific literature, but it is still too soon to know if such ideas are viable.
One of the issues that is evoked by any faster-than-light transport is time paradoxes: causality violations and implications of time travel. As if the faster than light issue wasn’t tough enough, it is possible to construct elaborate scenarios where faster-than-light travel results in time travel. Time travel is considered far more impossible than light travel.
Omega=the actual density to the critical density
If we triangulate Omega, the universe in which we are in, Omegam(mass)+ Omega(a vacuum), what position geometrically, would our universe hold from the coordinates given?
That's not all. The fact that space-time itself is accelerating - that is, the expansion of the universe is speeding up - also creates a horizon. Just as we could learn that an elephant lurked inside a black hole by decoding the Hawking radiation, perhaps we might learn what's beyond our cosmic horizon by decoding its emissions. How? According to Susskind, the cosmic microwave background that surrounds us might be even more important than we think. Cosmologists study this radiation because its variations tell us about the infant moments of time, but Susskind speculates that it could be a kind of Hawking radiation coming from our universe's edge. If that's the case, it might tell us something about the elephants on the other side of the universe.
Although a 1916 paper by Ludwig Flamm from the University of Vienna [4] is sometimes cited as giving the first hint of a wormhole, "you definitely need hindsight to detect it," says Matt Visser of Victoria University in Wellington, New Zealand. Einstein and Rosen were the first to take the idea seriously and to try to accomplish some physics with it, he adds. The original goal may have faded, but the Einstein-Rosen bridge still pops up occasionally as a handy solution to the pesky problem of intergalactic travel.
So "open doorways" and ideas of "tunneling" are always interesting in terms of how we might look at an area like GR in cosmology? Look for way in which such instances make them self known.
Are they applicable to the very nature of quantum perceptions that such probabilities could have emerged through them? Held to "time travel scenarios" and grabbed the history of what had already preceded us in past tense, could have been brought again forward for inspection?
Another deep quantum mystery for which physicists have no answer has to do with "tunneling" -- the bizarre ability of particles to sometimes penetrate impenetrable barriers. This effect is not only well demonstrated; it is the basis of tunnel diodes and similar devices vital to modern electronic systems.
Tunneling is based on the fact that quantum theory is statistical in nature and deals with probabilities rather than specific predictions; there is no way to know in advance when a single radioactive atom will decay, for example.
The probabilistic nature of quantum events means that if a stream of particles encounters an obstacle, most of the particles will be stopped in their tracks but a few, conveyed by probability alone, will magically appear on the other side of the barrier. The process is called "tunneling," although the word in itself explains nothing.
Chiao's group at Berkeley, Dr. Aephraim M. Steinberg at the University of Toronto and others are investigating the strange properties of tunneling, which was one of the subjects explored last month by scientists attending the Nobel Symposium on quantum physics in Sweden.
"We find," Chiao said, "that a barrier placed in the path of a tunneling particle does not slow it down. In fact, we detect particles on the other side of the barrier that have made the trip in less time than it would take the particle to traverse an equal distance without a barrier -- in other words, the tunneling speed apparently greatly exceeds the speed of light. Moreover, if you increase the thickness of the barrier the tunneling speed increases, as high as you please.
"This is another great mystery of quantum mechanics."
A Bose-Einstein condensate (such as superfluid liquid helium) forms for reasons that only can be explained by quantum mechanics. Bose condensates form at low temperature
The muon will travel faster than light in the ice (but of course still slower than the speed of light in vacuum), thereby producing a shock wave of light, called Cerenkov radiation. This light is detected by the photomultipliers, and the trace of the neutrinos can be reconstructed with an accuracy of a couple of degrees. Thus the direction of the incoming neutrino and hence the location of the neutrino source can be pinpointed. A simulation of a muon travelling through AMANDA is shown here (1.5 MB).
What are the main goals of the LHC?-The LHC will also help us to solve the mystery of antimatter. Matter and antimatter must have been produced in the same amounts at the time of the Big Bang. From what we have observed so far, our Universe is made of only matter. Why? The LHC could provide an answer.
It was once thought that antimatter was a perfect 'reflection' of matter - that if you replaced matter with antimatter and looked at the result in a mirror, you would not be able to tell the difference. We now know that the reflection is imperfect, and this could have led to the matter-antimatter imbalance in our Universe.
The strongest limits on the amount of antimatter in our Universe come from the analysis of the diffuse cosmic gamma-rays arriving on Earth and the density fluctuations of the cosmic background radiation. If one asumes that after the Big Bang, the Universe separated somehow into different domains where either matter or antimatter was dominant, then at the boundaries there should be annihilations, producing cosmic gamma rays. In both cases the limit proposed by current theories is practically equivalent to saying that there is no antimatter in our Universe.
Of course this information is based on 2003 data but the jest of the idea here is that in order to go to a "fast forward" the conditions had to exist previously that did not included "sterile neutrinos" and were a result of this "cross over."
The knowledge of Cyphering, hath drawne on with it a knowledge relative unto it, which is the knowledge of Discyphering, or of Discreting Cyphers, though a man were utterly ignorant of the Alphabet of the Cypher, and the Capitulations of secrecy past between the Parties. Certainly it is an Art which requires great paines and a good witt and is (as the other was) consecrate to the Counsels of Princes: yet notwithstanding by diligent prevision it may be made unprofitable, though, as things are, it be of great use. For if good and faithfull Cyphers were invented & practised, many of them would delude and forestall all the Cunning of the Decypherer, which yet are very apt and easie to be read or written: but the rawnesse and unskilfulnesse of Secretaries, and Clarks in the Courts of Princes, is such, that many times the greatest matters are Committed to futile and weake Cyphers.
But it may be, that in the enumeration, and, as it were, taxation of Arts, some may thinke that we goe about to make a great Muster-rowle of Sciences, that the multiplication of them may be more admired; when their number perchance may be displayed, but their forces in so short a Treatise can hardly be tried. But for our parts wee doe faithfully pursue our purpose, and in making this Globe of Sciences, we would not omitt the lesser and remoter Ilands. Neither have we (in our opinion) touched these Arts perfunctorily, though cursorily; but with a piercing stile extracted the marrow and pith of them out of a masse of matter. The judgement hereof we referre to those who are most able to judge of these Arts. For seeing it is the fashion of many who would be thought to know much, that every where making ostentation of words and outward termes of Arts, they become a wonder to the ignorant, but a derision to those that are Masters of those Arts: we hope that our Labours shall have a contrarie successe, which is, that they may arrest the judgment of every one who is best vers'd in every particular Art; and be undervalued by the rest . As for those Arts which may seeme to bee of inferior ranke and order, if any man thinke wee attribute too much unto them; Let him looke about him and hee shall see that there bee many of speciall note and great account in their owne Countrie, who when they come to the chiefe City or feat of the Estate, are but of mean ranke and scarcely regarded: so it is no marvaile if these sleighter Arts, placed by the Principall and supreme Sciences, seeme pettie things; yet to those that have chosen to spend their labours and studies in them, they seeme great and excellent matters. And thus much of the Organ of Speech. -- Francis Bacon, The Advancement and Proficience of Learning, p 257-71, Book VI, 1640.
We've learnt in the natural sciences that the key to understanding can often be found if we lift certain dividing lines in our minds. Newton showed that the apple falls to the ground according to the same laws that govern the Moon's orbit of the Earth. And with this he made the old differentiation between earthly and heavenly phenomena obsolete. Darwin showed that there is no dividing line between man and animal. And Einstein lifted the line dividing space and time. But in our heads, we still draw a dividing line between "reality" and "knowledge about reality", in other words between reality and information. And you cannot draw this line. There is no recipe, no process for distinguishing between reality and information. All this thinking and talking about reality is about information, which is why one should not make a distinction in the formulation of laws of nature. Quantum theory, correctly interpreted, is information theory.
Innatism is a philosophical doctrine introduced by Plato in the socratic dialogue Meno which holds that the mind is born with ideas/knowledge, and that therefore the mind is not a tabula rasa at birth. It asserts therefore that not all knowledge is obtained from experience and the senses. Innatism is the opposite of empiricism.
Plato claimed that humans are born with ideas/forms in the mind that are in a dormant state. He claimed that we have acquired these ideas prior to our birth when we existed as souls in the world of Forms. To access these, humans need to be reminded of them through proper education and experience.
"There comes a time when the mind takes a higher plane of knowledge but can never prove how it got there. All great discoveries have involved such a leap. The important thing is not to stop questioning." Albert Einstein (1879- 1955)
But the presence of an event horizon implies a finite Hawking temperature and the conditions for defining the S Matrix cannot be fulfilled. This lack of an S Matrix is a formal mathematical problem not only in string theory but also in particle theories.
One recent attempt to address this problem invokes quantum geometry and a varying speed of light. This remains, as they say, an active area of research. But most experts doubt that anything so radical is required.
SNOThe Sudbury Neutrino Observatory is a collaborative effort among physicists from Canada, the U.K., and the U.S. Using 1,000 tons of so-called heavy water and almost 10,000 photon detectors, they measure the flux, energy, and direction of solar neutrinos, which originate in the sun. SNO, located 6,800 feet underground in an active Ontario nickel mine, can also detect the other two types of neutrinos, muon neutrinos and tau neutrinos. In 2001, just two years after the observatory opened, physicists at SNO solved the 30-year-old mystery of the "missing solar neutrinos." They found that the answer lies not with the sun—where many physicists had suspected that solar neutrinos undergo changes—but with the journey they take from the core of the sun to the Earth.
Some theorists envision the universe as multidimensional space-time embedding a membranous entity, called a brane, also of multiple dimensions. Diagram depicts familiar 3-dimensional space (time not shown) as a vertical line. At every point along line, one extra dimension curls around with a radius (r) of no more that about 10–19 meter. Perpendicular to every point of the brane extends the bulk, another extra dimension.
That's not all. The fact that space-time itself is accelerating - that is, the expansion of the universe is speeding up - also creates a horizon. Just as we could learn that an elephant lurked inside a black hole by decoding the Hawking radiation, perhaps we might learn what's beyond our cosmic horizon by decoding its emissions. How? According to Susskind, the cosmic microwave background that surrounds us might be even more important than we think. Cosmologists study this radiation because its variations tell us about the infant moments of time, but Susskind speculates that it could be a kind of Hawking radiation coming from our universe's edge. If that's the case, it might tell us something about the elephants on the other side of the universe.
"Observations always involve theory."Edwin Hubble
As the Universe expands, galaxies become more and more distant from each other. For an observer, such as ourselves, it appears that all other galaxies fly away from us. The further the galaxy, the faster it appears to recede. This recession affects the light emitted by the distant galaxies, stretching the wavelengths of emitted photons due to the Doppler redshift effect. The distance between galaxies is proportionalto the measure of this effect 1+z, where z is what astronomers call redshift. The redshift can be measured for each object if its spectrum is measured.
Sorry about the quality of artistic rendition. But you get the jest right?
Current evidence shows that neutrinos do oscillate, which indicates that neutrinos do have mass. The Los Alamos data revealed a muon anti-neutrino cross over to an electron neutrino. This type of oscillation is difficult to explain using only the three known types of neutrinos. Therefore, there might be a fourth neutrino, which is currently being called a "sterile" neutrino, which interacts more weakly than the other three neutrinos.
Instead of the Newtonian inverse square law you’ll have an inverse fourth power law. This signature is being looked for in the ongoing experiments.
The Los Alamos data revealed a muon anti-neutrino cross over to an electron neutrino. This type of oscillation is difficult to explain using only the three known types of neutrinos.
Scientists using NASA's Hubble Space Telescope have discovered that dark energy is not a new constituent of space, but rather has been present for most of the universe's history. Dark energy is a mysterious repulsive force that causes the universe to expand at an increasing rate. Investigators used Hubble to find that dark energy was already boosting the expansion rate of the universe as long as nine billion years ago. This picture of dark energy is consistent with Albert Einstein's prediction of nearly a century ago that a repulsive form of gravity emanates from empty space. Data from Hubble provides supporting evidence to help astrophysicists to understand the nature of dark energy. This will allow them to begin ruling out some competing explanations that predict that the strength of dark energy changes over time.
All events shown here (except KEK test detector) were generated by Monte-Carlo simulation program, written by Clark. The visualizing software which produced the detector images was written by Tomasz.
Quantum physics has revealed a stunning truth about “nothing”: even the emptiest vacuum is filled with elementary particles, continually created and destroyed. Particles appear and disappear, flying apart and coming together, in an intricate quantum dance. This far-reaching consequence of quantum mechanics has withstood the most rigorous experimental scrutiny. In fact, these continual fluctuations are at the heart of our quantum understanding of nature.
The dance of quantum particles has special significance today because it contributes to the dark energy that is driving the universe apart. But there’s a problem: the vacuum has too much energy. A naive theoretical estimate gives an amount about 10120 times too large to fit cosmological observations. The only known way to reduce the energy is to cancel contributions of different particle species against each other, possibly with a new symmetry called supersymmetry. With supersymmetry the result is 1060 times better—a huge improvement, but not enough. Even with supersymmetry, what accounts for the other 60 orders of magnitude is still a mystery.
Physics theory predicts that one of the most important particles in the quantum vacuum is the Higgs particle. The Higgs pervades the vacuum, slowing the motion of particles, giving them mass, and preventing atoms from disintegrating. Since it fills the vacuum, the Higgs itself contributes to the embarrassing factor of 10120.
The next accelerators are opening a window on the pivotal role of symmetry in fundamental physics. New discoveries will teach us about the role of the Higgs particle and supersymmetry in defining the vacuum. Such discoveries are key to understanding what tames the quantum vacuum, a topic that is fundamental to any real understanding of the mysterious dark energy that determines the destiny of our cosmos.
"In fact, these continual fluctuations are at the heart of our quantum understanding of nature."
The only known way to reduce the energy is to cancel contributions of different particle species against each other, possibly with a new symmetry called supersymmetry.
Particle physics is in the midst of a great revolution. Modern data and ideas have challenged long-held beliefs about matter, energy, space and time. Observations have confirmed that 95 percent of the universe is made of dark energy and dark matter unlike any we have seen or touched in our most advanced experiments. Theorists have found a way to reconcile gravity with quantum physics, but at the price of postulating extra dimensions beyond the familiar four dimensions of space and time. As the magnitude of the current revolution becomes apparent, the science of particle physics has a clear path forward. The new data and ideas have not only challenged the old ways of thinking, they have also pointed to the steps required to make progress. Many advances are within reach of our current program; others are close at hand. We are extraordinarily fortunate to live in a time when the great questions are yielding a whole new level of understanding. We should seize the moment and embrace the challenges.
Superstrings: A computer's graphical representation of multi-dimensional spacetime
Right now is a time of radical change in particle physics. Recent experimental evidence demands a revolutionary new vision of the universe. Discoveries are at hand that will stretch the imagination with new forms of matter, new forces of nature, new dimensions of space and time. Breakthroughs will come from the next generation of particle accelerators — the Large Hadron Collider, now under construction in Europe, and the proposed International Linear Collider. Experiments at these accelerators will revolutionize your concept of the universe.
A new cutting:edge experiment aims to discover how exactly cosmic rays and the Sun may influence the formation of low:level clouds, and possibly climate change.
More than two centuries ago, the British Astronomer Royal William Herschel noted a correlation between sunspots ? an indicator of solar activity : and the price of wheat in England. He suggested that when there were few sunspots, prices rose.
However, up until recently, there was little to back up this hypothesis. Today, inside an unassuming ? some would say decrepit:looking ? building at Cern, the Cloud (Cosmics Leaving OUtdoor Droplets) experiment might help explain how the Sun affects the climate.
NASA will host a media teleconference with Hubble Space Telescope astronomers at 1 p.m. EST Thursday, Nov. 16, to announce the discovery that dark energy has been an ever-present constituent of space for most of the universe's history.
Although it didn't properly describe strong interactions, in studying string theory physicists stumbled upon an amazing mathematical structure. String theory has turned out to be far richer than people originally anticipated. For example, people found that a certain vibrational state of the string has zero mass and spin 2. According to Einstein's theory of gravity, the gravitational force is mediated by a particle with zero mass and spin 2. So string theory is, among many other things, a theory of gravity!
TWO UNIVERSES of different dimension and obeying disparate physical laws are rendered completely equivalent by the holographic principle. Theorists have demonstrated this principle mathematically for a specific type of five-dimensional spacetime ("anti–de Sitter") and its four-dimensional boundary. In effect, the 5-D universe is recorded like a hologram on the 4-D surface at its periphery. Superstring theory rules in the 5-D spacetime, but a so-called conformal field theory of point particles operates on the 4-D hologram. A black hole in the 5-D spacetime is equivalent to hot radiation on the hologram--for example, the hole and the radiation have the same entropy even though the physical origin of the entropy is completely different for each case. Although these two descriptions of the universe seem utterly unalike, no experiment could distinguish between them, even in principle.
Holography encodes the information in a region of space onto a surface one dimension lower. It sees to be the property of gravity, as is shown by the fact that the area of th event horizon measures the number of internal states of a blackhole, holography would be a one-to-one correspondence between states in our four dimensional world and states in higher dimensions. From a positivist viewpoint, one cannot distinguish which description is more fundamental.Pg 198, The Universe in Nutshell, by Stephen Hawking
This year marks the hundredth anniversary of Einstein's "miraculous year", 1905, when he formulated special relativity, and explained the origin of the black body spectrum and Brownian motion. In honor of this occasion, I will describe the modern view of spacetime. After reviewing the properties of spacetime in general relativity, I will provide an overview of the nature of spacetime emerging from string theory. This is radically different from relativity. At a perturbative level, the spacetime metric appears as ``coupling constants" in a two-dimensional quantum field theory. Nonperturbatively (with certain boundary conditions), spacetime is not fundamental but must be reconstructed from a holographic, dual theory. I will conclude with some recent ideas about the big bang arising from string theory.
The tests use the ALICE cosmic muon trigger detector ACORDE, as well as a specially designed UV laser system, to produce tracks in the detector. Preliminary analysis of the cosmic-ray events and the laser-induced tracks indicate that the drift velocity and diffusion of electrons liberated by traversing charged particles, as well as the spatial resolution, are very close to the design values.
For example, people found that a certain vibrational state of the string has zero mass and spin 2. According to Einstein's theory of gravity, the gravitational force is mediated by a particle with zero mass and spin 2. So string theory is, among many other things, a theory of gravity!
