EldwinSchrodinger @ Luna Lovegood Biography
Luna Lovegood is the quirky Ravenclaw who is in the same year as Ginny Weasley. Luna is introduced in Order in the Phoenix where she is first described as having protuberant eyes that [give] her a permanently surprised look. Luna is first introduced to the trio and Neville during the train ride to Hogwarts. There, Luna is found reading a copy of The Quibbler (upside down), in which we discover that her father is the editor for that same magazine. Harry and the others notice at the strange attire Luna sports a necklace made out of Butterbeer caps and placing her wand behind her left ear. Her strange comments and excessive laughing help fully characterize Luna into one word: strange. In retrospect, Luna is not your average witch. Her bizarre tastes and odd approach towards her classmates makes her a perfect target for ridicule, which causes Luna to lack genuine friends.
Luna is constantly made fun of by her peers. For example, many refer to her as Loony Lovegood when she is the subject of casual conversations. Her possessions are also being stolen year round, where Luna is forced to place notices requesting her belongings at the end of the year. Despite the negativity she receives, Luna is overall a kind and understanding character. Lunas oddities and outspokenness does not bring her down in the least. She is unlike most students at Hogwarts; in the sense that she presents herself in a very calm and serene manner. She is fully aware of her uniqueness, which does give her a certain pride and dignity. Lunas spirit is surprisingly high, despite many downsides of her life; for example, her mothers tragic death. Luna never fights back or complains about her constant ridicules or when she is attempting to gather all her items that have been taken throughout the school year - truly evoking a genuine and impressionable character.
Lunas development in Order of the Phoenix transitions from being just the weird girl to the loyal friend who proves her friendship towards Harry, Ron, and Hermione. She valiantly fights against the Death Eaters in the Department of Mysteries, as well as joining the DA club. Her relationship towards Harry develops at the end of the book when he catches Luna posting the notices that request her belongings. Harrys loss of his godfather brings him to attempt to contact Sirius by any means possible, so speaking to Luna creates a bond between the two since they have both suffered the loss of loved ones.
Lunas appearance in Half-Blood Prince is not as significant as the prior book but her loyalty towards Harry and the others as still strong and evident. Lunas relationship with Harry culminates when he decides to ask Luna to one of Professor Slughorns parties. Lunas loyalty is also evident when she is mentioned carrying the fake galleon that was used during the span of which the DA club existed back in Order in the Phoenix.
For what lies ahead for Luna in the last installment, we are not yet certain. But from the looks of it, we are certain in seeing Luna play some integral role to both Harry and the others. In addition, most fans cannot wait until the release of the fifth installment of the films will be released where we will get the chance to see Luna onscreen and enjoy the quirkiness that is Luna Lovegood!
Labels: celebrities
EldwinSchrodinger @ Quantum Teleportation
Teleportation is the name given by science fiction writers to the feat of making an object or person disintegrate in one place while a perfect replica appears somewhere else. How this is accomplished is usually not explained in detail, but the general idea seems to be that the original object is scanned in such a way as to extract all the information from it, then this information is transmitted to the receiving location and used to construct the replica, not necessarily from the actual material of the original, but perhaps from atoms of the same kinds, arranged in exactly the same pattern as the original. A teleportation machine would be like a fax machine, except that it would work on 3-dimensional objects as well as documents, it would produce an exact copy rather than an approximate facsimile, and it would destroy the original in the process of scanning it. A few science fiction writers consider teleporters that preserve the original, and the plot gets complicated when the original and teleported versions of the same person meet; but the more common kind of teleporter destroys the original, functioning as a super transportation device, not as a perfect replicator of souls and bodies.
In 1993 an international group of six scientists, including IBM Fellow Charles H. Bennett, confirmed the intuitions of the majority of science fiction writers by showing that perfect teleportation is indeed possible in principle, but only if the original is destroyed. In subsequent years, other scientists have demonstrated teleportation experimentally in a variety of systems, including single photons, coherent light fields, nuclear spins, and trapped ions. Teleportation promises to be quite useful as an information processing primitive, facilitating long range quantum communication (perhaps unltimately leading to a "quantum internet"), and making it much easier to build a working quantum computer. But science fiction fans will be disappointed to learn that no one expects to be able to teleport people or other macroscopic objects in the foreseeable future, for a variety of engineering reasons, even though it would not violate any fundamental law to do so.
In the past, the idea of teleportation was not taken very seriously by scientists, because it was thought to violate the uncertainty principle of quantum mechanics, which forbids any measuring or scanning process from extracting all the information in an atom or other object. According to the uncertainty principle, the more accurately an object is scanned, the more it is disturbed by the scanning process, until one reaches a point where the object's original state has been completely disrupted, still without having extracted enough information to make a perfect replica. This sounds like a solid argument against teleportation: if one cannot extract enough information from an object to make a perfect copy, it would seem that a perfect copy cannot be made. But the six scientists found a way to make an end run around this logic, using a celebrated and paradoxical feature of quantum mechanics known as the Einstein-Podolsky-Rosen effect. In brief, they found a way to scan out part of the information from an object A, which one wishes to teleport, while causing the remaining, unscanned, part of the information to pass, via the Einstein-Podolsky-Rosen effect, into another object C which has
never been in contact with A. Later, by applying to C a treatment depending on the scanned-out information, it is possible to maneuver C into exactly the same state as A was in before it was scanned. A itself is no longer in that state, having been thoroughly disrupted by the scanning, so what has been achieved is teleportation, not replication.
As the figure to the left suggests, the unscanned part of the information is conveyed from A to C by an intermediary object B, which interacts first with C and then with A. What? Can it really be correct to say "first with C and then with A"? Surely, in order to convey something from A to C, the delivery vehicle must visit A before C, not the other way around. But there is a subtle, unscannable kind of information that, unlike any material cargo, and even unlike ordinary information, can indeed be delivered in such a backward fashion. This subtle kind of information, also called "Einstein-Podolsky-Rosen (EPR) correlation" or "entanglement", has been at least partly understood since the 1930s when it was discussed in a famous paper by Albert Einstein, Boris Podolsky, and Nathan Rosen. In the 1960s John Bell showed that a pair of entangled particles, which were once in contact but later move too far apart to interact directly, can exhibit individually random behavior that is too strongly correlated to be explained by classical statistics. Experiments on photons and other particles have repeatedly confirmed these correlations, thereby providing strong evidence for the validity of quantum mechanics, which neatly explains them. Another well-known fact about EPR correlations is that they cannot by themselves deliver a meaningful and controllable message. It was thought that their only usefulness was in proving the validity of quantum mechanics. But now it is known that, through the phenomenon of quantum teleportation, they can deliver exactly that part of the information in an object which is too delicate to be scanned out and delivered by conventional methods.
This figure compares conventional facsimile transmission with quantum teleportation (see above). In conventional facsimile transmission the original is scanned, extracting partial information about it, but remains more or less intact after the scanning process. The scanned information is sent to the receiving station, where it is imprinted on some raw material (eg paper) to produce an approximate copy of the original. By contrast, in quantum teleportation, two objects B and C are first brought into contact and then separated. Object B is taken to the sending station, while object C is taken to the receiving station. At the sending station object B is scanned together with the original object A which one wishes to teleport, yielding some information and totally disrupting the state of A and B. The scanned information is sent to the receiving station, where it is used to select one of several treatments to be applied to object C, thereby putting C into an exact replica of the former state of A.
Labels: Quantum Mechanics
EldwinSchrodinger @ Hole in the universe
Astronomers have stumbled upon a tremendous hole in the universe. That's got them scratching their heads about what's just not there. The cosmic blank spot has no stray stars, no galaxies, no sucking black holes, not even mysterious dark matter. It is 1 billion light years across of nothing. That's an expanse of nearly 6 billion trillion miles of emptiness, a University of Minnesota team announced Thursday.
Astronomers have known for many years that there are patches in the universe where nobody's home. In fact, one such place is practically a neighbor, a mere 2 million light years away. But what the Minnesota team discovered, using two different types of astronomical observations, is a void that's far bigger than scientists ever imagined.
"This is 1,000 times the volume of what we sort of expected to see in terms of a typical void," said Minnesota astronomy professor Lawrence Rudnick, author of the paper that will be published in Astrophysical Journal. "It's not clear that we have the right word yet ... This is too much of a surprise."
Rudnick was examining a sky survey from the National Radio Astronomy Observatory, which essentially takes radio pictures of a broad expanse of the universe. But one area of the universe had radio pictures indicating there was up to 45 percent less matter in that region, Rudnick said.
The rest of the matter in the radio pictures can be explained as stars and other cosmic structures between here and the void, which is about 5 to 10 billion light years away.
Rudnick then checked observations of cosmic microwave background radiation and found a cold spot. The only explanation, Rudnick said, is it's empty of matter.
It could also be a statistical freak of nature, but that's probably less likely than a giant void, said James Condon, an astronomer at the National Radio Astronomy Observatory. He wasn't part of Rudnick's team but is following up on the research.
"It looks like something to be taken seriously," said Brent Tully, a University of Hawaii astronomer who wasn't part of this research but studies the void closer to Earth.
Tully said astronomers may eventually find a few cosmic structures in the void, but it would still be nearly empty.
Holes in the universe probably occur when the gravity from areas with bigger mass pull matter from less dense areas, Tully said. After 13 billion years "they are losing out in the battle to where there are larger concentrations of matter," he said.
Labels: Astronomy
EldwinSchrodinger @ GRB (Gamma Ray Burst) , AGN (Active Galactic Nuclei)
Gamma-ray Bursts
Gamma-ray Bursts (GRBs) were first discovered accidentally in the late 1960s by the Vela satellites, which were actually being used to ensure no nuclear devices were being tested in the atmosphere or space. However, instead of providing proof of illegal testing, the gamma-ray events detected were found to be cosmological in origin (i.e., from outside the atmosphere). Over the past 30-40 years, much progress has been made in understanding these events. It is found that there are 2 "populations", with some bursts lasting only milliseconds, while others have a duration of a few hundred seconds. A plot of number of bursts against duration shows the "dividing line" between the groups is at about 2 seconds, with peaks in the distribution occuring at ~0.3 and 30 seconds.Because we do not know in advance when a GRB will occur, it has not been possible to observe the shortest wavelength events (it takes more than a few seconds to point a satellite in the correct direction!); however, some information is known about typical longer duration GRBs. They are found to be external to our galaxy, millions of light-years away (see here for a list of GRBs with known redshifts), and are probably formed when a very massive star reaches the end of its life. It is known that stars with M > 10 Msun form supernova explosions when they die, leaving behind a compact remnant, either a neutron star or a black hole, depending on their mass. When even more massive stars (> 40 Msun?) collapse, it is possible that the explosion is not the same as a supernova, with the energy output being about 100 times greater; these have been termed hypernovae and are likely to be one way to form GRBs.
An alternative explanation for the formation of a GRB is the merging of 2 neutron stars which were previously in a binary system. As they orbit each other, rotational energy is lost and converted to gravitational energy. This causes the orbit to decay and the neutron stars spiral into each other and merge, forming a black hole. This may be the route to forming one of the shorter (< href="http://www.ligo.caltech.edu/">LIGO (the Laser Interferometer Gravitational Wave Observatory) should one day be able to detect.
Although GRBs are initially detected at gamma-ray energies, "afterglows" at longer wavelengths can also be observed. BeppoSAX, an Italian X-ray satellite, first detected X-ray emission from a GRB in the late 1990s. Afterglows are also seen in the optical and radio wavebands as well. In fact, it was the discovery of these afterglows that made the redshift determination possible.
The Swift Gamma-ray mission, launched on 20th November 2004 is a multi-wavelength observatory (optical, X-ray and gamma-ray), designed to study GRBs. See the UK Swift Science Data Centre for more details.
Active Galactic Nuclei - a basic introduction
Most of my PhD research concentrated on X-ray observations of Active Galactic Nuclei (AGN), both the lower-luminosity Seyfert Galaxies and the higher-luminosity Quasi-Stellar Objects (QSOs; sometimes also referred to as quasars). It is generally thought that AGN are powered by matter from an accretion disc fuelling a central, supermassive (~106-109 Msun) black hole.All galaxies may contain central, massive black holes, but only those which are adequately fuelled are seen as active. AGN are the brightest continuously emitting objects in the Universe (Gamma Ray Bursts are much brighter, but for only a short period of time) and can reach bolometric luminosities (that is, summed over all wavelengths) of 1040-1048 erg s-1. (An erg is the unit of energy most astronomers use; it is equal to 10-7 J.) The luminosity emitted by the nucleus can be as bright (in Seyfert galaxies) or brighter (in the case of QSOs) than all the stars of the host galaxy (~1011 Lsun) put together. Because of this, the active galaxy can appear as a point source (like a single star) to a distant observer; this is what led to the term Quasi-Stellar objects.
Because AGN are so luminous, they can be seen out to high redshifts/distances. Because light travels at a finite speed (3 x 108 m s-1), the further away an object is, the longer it takes for its light to reach us. When we observe radiation from an object at a redshift of 6, we are looking back almost 95% of the age of the Universe! The closer we look to the Big Bang, the more we should be able to understand about the evolution of the Universe as a whole.
Although we are pretty certain that AGN have central supermassive black holes, it is not yet possible to image them directly. This will (hopefully!) be resolved by the advent of X-ray interferometry. Interferometry means that there are lots of telescopes, all linked together, observing the same object. This allows much finer resolution than can be obtained by a single instrument. Interferometry is already used in different wavebands; for example, in the UK there is a radio interferometer called MERLIN (Multi-Element Radio-Linked Interferometer Network). Thus far, the design of X-ray interferometers has been hampered by the failure to build suitable diffraction-limited optics. However, such optics are now becoming feasible, so X-ray interferometry should be on the way!
X-rays are emitted by high-energy processes, making them a very useful tool for astrophysics. In the case of AGN, the X-rays are thought to come from either the inner regions of the accretion disc, or a hot corona of electrons above the disc. The effects of strong gravity reveal themselves in X-ray spectra, allowing astronomers to analyse the environments around supermassive black holes.
Extracted from here
Labels: Cosmology
