Juli 2007
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Nobel Laureates in Physics 1901 - 1999...
Tony Smith's WWW Home Page (Fysik, Matematik, Kvantemekanik, Quark)
The MAD Scientist Network (Ask-A-Scientist)
On-line Animations of Time Evolving Physical Systems
10-Jan-2002 Closest Model Yet Of The Physics Of Turbulent Flow
Exploring the electromagnetic spectrums
ScienceDaily Magazine , IOL: Science/Tech home , BBC News Sci/Tech , CERN Courier , PopSci.com: Popular Science , Science News Online , Scientific American , UniSci - All Science News In One Place (opdateres ikke mere) , AIP Physics News , nature.com: News , New Scientist: News , Physics Today , Physics News Update , Physical Review Focus
PhysicsWeb (REG) , Nature (REG Kun indeks frit tilgængeligt) , science Magazine (REG) , New Scientist (REG)
Electronic Buyers' News Online ebnews
Berkeley Madonna Citat: "...is arguably the fastest, most convenient, general purpose differential equation solver available today. It is relatively inexpensive and runs on both Windows and Mac OS. Developed on the Berkeley campus under the sponsorship of NIH and NSF, it is currently used by academic institutions for constructing mathematical models in both teaching and research..."
The NASA Astrophysics Data System mirrored worldwide
Welcome to StatLib Citat: "...a system for distributing statistical software, datasets, and information by electronic mail, FTP and WWW..."
SAL (Scientific Applications on Linux) (Physics & Astronomy)
ASCL Astrophysics Source Code Library: Archive
Science's Next Wave Citat: "...is a weekly online publication that covers scientific training, career development, and the science job market. The Next Wave is published by SCIENCE magazine and the American Association for the Advancement of Science. It is a not-for-profit publication..."
The Institute of Physics [IoP] Citat: "...is an international learned society and professional body for the advancement and dissemination of physics, pure and applied, and promotion of physics education, working through..." (REG)
Ungdommens Naturvidenskabelige Forening UNF
Paul Marmet: List of Papers and Web Sites
Stanford: Top Cited HEP Articles, from SPIRES-HEP and the SLAC Library
Elementistory (Historisk om grundstoffer)
Trace Sciences: Periodic Table (isotopes)
29-Jan-2002 Standard Model In Trouble Again: Berkeley Lab Theory
BBC News: 20 July, 2000, Science finds particle perfection Citat: "...The building blocks of the Universe consist of:
Anti-Proton Mass And Charge Measured For First Time Citat: "...In this case, the values agree with those of the proton (allowing for the opposite charge) to within 60 parts per billion...."
In Search of Antimatter Web archive mirror Citat: "...Two international collaborations have announced definitive answers to one small piece of the universe's matter-antimatter asymmetry problem..."
22 August, 2001 Physicists make 'strange' matter
CERN Courier: How CP violation came to B
Everything you ever wanted to know about CP violation and never dared to ask
BBC
News 5-3-1999: 'Sensational' anti-matter discovery Citat: "...The phenomenon
they think they spotted is technically called direct Charge-Parity (CP)
violation. It means that particles behave differently if you swap matter
for anti-matter and also swap left and right. ...The observation of direct
CP violation is an exciting one for physicists as it disagrees with all
the currently held theories about the nature of matter. "
CERN Courier VOLUME 40 \¦ NUMBER 4 \¦ MAY 2000: New precision result on CP violation
New Type of Radioactivity Discovered at ORNL Citat: "...simultaneous emission of two protons from the decaying nucleus of an atom. The discovery of the protons, which may have been initially bound together in an ephemeral helium-2 nucleus as they were emitted from a neon-18 nucleus, is significant...." ( PhysicsWeb: Physicists discover new kind of radioactivity)
Exciting times for heavy nuclei [e.g.tellurium-125]
Citat: "... [1 Sep 2000] A previously unknown nuclear phenomenon has
been observed by an international collaboration of physicists. They found
that the energy released from a nucleus relaxing to a lower energy state
can be used to excite an orbiting electron into a higher energy state.
Nuclear and atomic processes are not usually linked in this way, mainly
because nuclear phenomena involve energies up to a million times greater
than atomic effects. But Carreyre and co-workers have found an exception
to the rule (2000 Phys. Rev. C 62 024311)...An important property of the
new process is that it is strongly resonant: a small increase in the atomic
excitation energy can produce a large variation in the half-life and rate
of nuclear decay. Carreyre's team suspects that the transfer of energy
between nucleus and surrounding electrons could account for apparent anomalies
in the lifetimes of certain radioactive elements. Interestingly, the effect
is exactly the reverse of a process recently observed, in which the nucleus
is excited by a near-resonant electron transition (Kishimoto et al 2000
Phys. Rev. Lett. 85 1831)
The phenomenon may have important implications for astrophysics.
The highly ionized gases, or plasmas, that exist inside stars contain nuclear
species whose lifetimes may be affected by the process. If that is the
case, this may change our understanding of how the elements are created
inside stars...."
Scientific American, October 2000, Schrödinger's
SQUID,
In superconducting loops, electric current flows both ways at once
Citat: "...
The two new experiments take things to a substantially more
macroscopic level. They were conducted by Jonathan Friedman,
James Lukens and their co-workers at the State University of
New York at Stony Brook and by Caspar van der Wal, Johan E.
Mooij and their co-workers at the Delft University of
Technology in the Netherlands. Both groups used
SQUIDs--superconducting
quantum interference devices.
Quantum effects permit only certain discrete amounts of magnetic
flux to thread through such a superconducting loop.
...
The superposition state does not correspond to a billion electrons
flowing one way and a billion others flowing the other way.
Superconducting electrons move en masse. All the superconducting
electrons in the SQUID flow both ways around the loop at
once when they are in the Schrödinger's cat state.
..."
*Supercond. Sci.
Technol. 12 No 8 (August 1999) 538-554: A superconducting transistor based
on quasiparticle trapping [quatratran]
*Applied
Physics Letters--July 17, 2000 Volume 77, Issue 3: Superconducting device
with transistor-like properties including large current amplification
Citat: "...We have fabricated and studied a stacked superconducting double
tunnel junction device with transistor-like properties..."
(fundet via denne adresse): Physics
Web 13 Jul 2000: Superconducting device with current gain (se under
"related articles" i venstre side)
Ing 1998: Tunnel transistor GaAs 77K
1996: The Resonant Tunnelling Transistor
1998 feb 4 Physics News Update: Story of Quantum Tunneling Transistor
1998 feb 4 Physics News Update: Quantum Tunneling Transistor
EBN Archive 19991129: Researchers probe transistor's future at IEDM:
A late paper from IBM's Watson Research Center Citat: "...(Yorktown Heights, N.Y.) describes devices fabricated at 50-nm design rules that were created with very low threshold voltages. The low-Vt devices were used to create a 101-stage CMOS ring oscillator, which has a gate delay per stage of 6.4 picoseconds at --100°C the fastest CMOS switching performance reported to date..."EBN archive 19991208: IEDM Researchers report on latest quantum work: Citat: "...Researchers at this week's International Electron Devices Meeting (IEDM) reported on the latest achievements in SETs (single-electron transistors), nano-crystal memories, and quantum mechanical effects in general...."
Physics World, September 1998, Volume 11 Issue 9 Article 7: Single-electron transistors [SET]
EBN Archive 19991125: New gate geometry opens way for ultra-fine transistors Citat: "...CMOS transistor that could operate at 25-nanometer (0.025-micron) gate lengths..."
EBN Archive 19991208: SOI takes transistor gates below 100 nm Citat: "..."The UTB SOI MOSFET shows good short channel effect and is a promising candidate for the sub-20-nm regime," Choi said..."
Lucent: smallest MOS transistors 60nm
14-Feb-2002 Stimulated Emission By Three-Photon Excitation Seen
07-Jan-2002 Storing Light In A Solid Material: Another First
2002-01-04 Gennembrud indenfor optisk dataoverførsel ( Mini-Lasers and Silicon on Sapphire Technology Lead to Speedier and Cost-Effective Interconnects Between Computer Chips )
13 December 2001 Single-photon machine gears up
20. november 2001 Forskere udvikler optisk mikroprocessor Citat: "...Fremtidens processorer med terahertz-hastighed er rykket et skridt nærmere med et nyt forskningsresultat...."
Ingeniøren, 19/08/01 Første hvide lysdiode Citat: "...Effekten skyldes en særlig form for eksitation først opdaget i 1994...De resulterende elektron-hul par, der nu omfatter begge molekyler, henfalder ved udsendelse af fotoner, hvis bølgelængder dækker hele det synlige spektrum... levetid vil være mange gange større end elektriske pærers... (App. Phys. Let. 30/7-01)"..."
UniSci, 13-Aug-2001: Rochester's Infrared Detector Began Life In Russia Citat: "...The new device can detect single photons..."
Applied Physics Letters -- July 30, 2001 -- Volume 79, Issue 5 pp. 560-562 Citat: "...White light emission from blends of blue-emitting organic molecules: A general route to the white organic light-emitting diode?..." ( alternate address )
Nature, 31 July 2001: Organic white bulb mixed
Photonic Crystal and Photonic Band Gap Links ( Former address )
Scientific American, Cheap Light, Microlasers go deeper into the infrared to boost optical networking , Web archive mirror Citat: "...Still, engineering long-wavelength VCSELs--making quantum dots that have the necessary performance characteristics, for example--remains a challenge. But the payoff, cheap optical networks that reach all the way into your bedroom, suggests that these devices may experience a better fate than the optical computer...."
BBC News: 18 January, 2001, Light stopped in its tracks ( Nature ) ( Nature, PrePub ) ( Nature article PDF ) Citat: "...And, astonishingly, if the coupling laser is turned off while the probe pulse is inside the gas cloud, the probe pulse stops dead in its tracks. If the coupling beam is then turned back on, the probe pulse emerges intact, just as if it had been waiting to resume its journey. The biggest impact of this work could be in the burgeoning field of quantum computing and quantum communication...."
BBC News: 3 January, 2001, Sea mouse promises bright future Citat: "...The sea mouse, or Aphrodita, has spines that normally appear deep red in colour. But when light falls on a spine perpendicular to its axis, stripes of different colours appear - strong blues and greens. ... "The simple structure responsible for this effect is a remarkable example of photonic engineering by a living organism."... "These structures may have application in photonic communications, where there is much interest in fabricating photonic crystal fibres with similar morphology."..."
November 3, 2000: Cheesecloth-like photonics device bends light with little loss Citat: "...the cheesecloth-like structure can be considered essentially a wire for light...Because of the very small light loss, the technique offers the potential of ultimately replacing electronic chips with faster, cooler photonic chips...two-dimensional crystals are cheaper and far easier to build..."
October 6, 2000: Sandia VCSEL generates ultraviolet light Citat: "...Such lasers, called UV VCSELS (vertical-cavity surface-emitting lasers)...they produce shorter wavelengths than other lasers or LEDs, also may be used to write more information on CDs or DVDs...Sandia, a leader in developing and improving of VCSELS (which are now approaching 50 percent efficiency in infrared and red)..."
June 16, 2000: New Sandia vertical cavity surface emitting laser promises to reduce cost of fiber optics connections Citat: "...Sandia researchers have developed the first 1.3-micron electrically pumped vertical cavity surface emitting laser (VCSEL) grown on gallium arsenide. It promises to reduce the cost of high-speed fiber optics connections..."
September 18, 2000, ucsdnews Citat: "...Hartmann, an electrical and computer engineering graduate student at UC San Diego's Jacobs School of Engineering has invented a new line of high performance, low cost polymer microlenses...."
Cnet, August 31, 2000, Why photonics? Citat:"...Demand for photonic equipment is skyrocketing. Internet traffic on the backbone networks has been doubling every three months and shows no sign of abating. Companies are laying fiber in just about every cross-country right-of-way they can find. First it was along the railways, and now it's the gas pipelines, sewers and just about any conduit you can think of... "
Physics World, June 1999, Volume 12 Issue 6 Article 9: Quantum cascade lasers Citat: "...quantum cascade lasers can outperform diode lasers operating at the same wavelength by factors greater than 1000... The other revolutionary aspect of the quantum cascade laser is that it can be designed to emit at any wavelength over an extremely wide range ..."
09/03/2000, Ing: NKT vil lave fibre med huller Citat: "... DTU og NKT samarbejder om fremstilling af ny slags optiske fibre ... de nye krystalfibre har lavere tab end de traditionelle fibre med en kerne af massivt kvarts ... Krystalfibrene baserer sig på et andet fænomen, der kaldes fotonisk båndgab ..."
Ingeniøren nr. -3/1999: Dansk gennembrud i fiberoptik
Citat: "...
Danske og engelske forskere har sammen bevist, at optisk fiber
med huller i kan transportere lys over lange afstande
...
Efter de simpleste regler for lysstrålers brydning vil dette være
umuligt. Kort fortalt siger den simple teori, at lyset holdes
sammen af det højere brydningsindeks og ikke af det lavere
brydningsindeks.
...
Det ændrer verdenen dramatisk for fotoner, der vil løbe langs fiberen.
Der opstår nemlig et fotonisk båndgab, dvs. et område hvor
fotoner inden for et bestemt energiområde (eller bølgelængdeområde -
idet energi og bølgelængde er omvendt proportionale) ikke kan udbrede sig.
Den færdige fiber er ligesom en traditionel fiber tyndere end et
menneskehår, men indeholder 300-400 præcist kontrollerede
luftkanaler indeni. De første eksemplarer af den nye fibertype
blev straks analyseret og virkede fuldstændigt som forudsagt af modellen.
...
Resultaterne har allerede vakt stor opmærksomhed i forskerkredse.
Først blev de publiceret i Science den 20. november og kort efter
også omtalt i The Economist og Nature.
...
God til laserlys
Mere interessant er, at den nye type fibre udviser meget stor
dobbeltbrydning. Det betyder, at lys polariseret i to på hinanden
forskellige vinkelrette retninger ikke vil forstyrre hinanden.
Det sker normalt meget let i almindelige fibre. Fibrene er således
meget anvendelige til at transportere polariseret laserlys fra et
sted til et andet, f.eks. i et laboratorium. Da det er muligt at
designe fibre, hvor det meste af effekten går gennem luften, kan
man tilmed sende højere effekt end i kvartsfibre, som risikerer
at brænde sammen under meget høje laserenergier.
Da lyset udbreder sig delvist gennem et hul, kan man også forstille sig, at dette hul fyldes med en luftart,
og man via de optiske egenskaber kan analysere luftarten.
Derved har man en kompakt og følsom sensor.
Der er måske endnu større perspektiver i at lave to-dimensionale
strukturer baseret på fotoniske båndgab.
..."
Julia Wallace, University of Exeter: A Brief History of Quantum Computation
Google Web directory: Quantum Computing , Quantum Mechanics
David Deutsch's Home Page: Citat: "...Quantum theory, the Church-Turing principle and the universal quantum computer..."
The Centre for Quantum Computation: A short introduction to quantum computation
The Centre for Quantum Computation Citat: "...The discovery that quantum physics allows fundamentally new modes of information processing has required the existing theories of computation, information and cryptography to be superseded by their quantum generalisations. The Centre for Quantum Computation, part of the University of Oxford, conducts theoretical and experimental research into all aspects of quantum information processing, and into the implications of the quantum theory of computation for physics itself..."
15-Feb-2002 First Step To Noiseless Qubit For Quantum Computers
December 19, 2001, IBM's Test-Tube Quantum Computer Makes History Citat: "...First demonstration of Shor's historic factoring algorithm..."
CNN May 17, 2001 Quantum-light processor may thrash supercomputers Citat: "...Mimicking quantum mechanics and using laser technology, scientists have constructed the prototype of a lightning-fast computer that could render conventional supercomputers obsolete..."
Laser Focus World 18-3-2001: Quantum information processing may no longer face entanglement problems
EETIMES 17-1-2001: Optical components proposed for viable quantum computer ( ETDN mirror ) Citat: "...SANTA FE, N.M. - Researchers at Los Alamos National Laboratories claim to have originated a blueprint for room-temperature quantum computers using such optical components as beam splitters, phase shifters and photodetectors. ..."
CNN, August 15, 2000: IBM develops world's most advanced quantum computer [IBM News] Citat: "...IBM said the computer, which uses five atoms to work as its processor and memory, demonstrates for the first time the potential of such devices to solve certain problems at a rate remarkably faster [exponentially] than conventional computers. The experimental machine is considered the next step towards a new class of devices capable of superfast calculations. ..."
Science News June 3, 2000: Quantum quirks quicken thorny searches: Citat: "...A researcher [Low K. Grover] has come up with a quantum algorithm for identifying one or more items in a large, unsorted database when complete information about the search target is unavailable..."
Many-particle entanglement with Bose--Einstein condensates
Quantum leap for entanglement [17 Mar 2000] Citat: "...Entanglement is one of the most mysterious and fundamental properties of quantum mechanics. When two or more particles are "entangled", the wavefunction describing them cannot be factorized into a product of single-particle wavefunctions. This means that a measurement on one particle will immediately influence the state of the other particles in the entangled system. A group of physicists in the US has now "entangled" four particles for the first time (Nature 404 256)..."
Nature 398, 786 - 788 (1999): Coherent control of macroscopic quantum states in a single-Cooper-pair box Citat: "...Although the two-level system is macroscopic, containing a large number of electrons, the two charge states can be coherently superposed. The Cooper-pair box has therefore been suggested as a candidate for a quantum bit or 'qubit'--the basic component of a quantum computer...."
Quantum Physics, Electron Spin Resonance Transistors for Quantum Computing in Silicon-Germanium Heterostructures: Citat: "...Certain Silicon-Germanium alloys allow a qubit spacing as large as 200 nm, which is well within the capabilities of current lithographic techniques..."
Physics in Action, January 1999: Quantum engineering moves on
Quantum Optics and Atom Optics links (German Mirror)
The Stanford-Berkeley-MIT-IBM NMR Quantum Computation Project
Fransk, Claude Crepeau, kvante kryptografi. Mange referencer
caltech.edu: Quantum Information and Quantum Computation
Quantum Computation/Cryptography at Los Alamos
Scientific American 1998, 0698 issue: Quantum Computing with Molecules , Web archive mirror
Bell Labs, Lov K. Grover: Citat: "...The number of steps needed in Grover's algorithm is defined by the square root of the number items in the [unsorted] data base. For instance, in a database with a million entries, a quantum computer would need only 1,000 steps to find the correct solution...."
ScienceNews August 31, 1996: Quantum-Quick Queries
ScienceNews June 14, 1997: Divide and conquer for quantum computers
Java og Macromedia: Visual Quantum Mechanics VQM
Ralph C. Merkle's nanotechnology web site: Reversible Logic
This is an extended web version of the article published in the Feb/Mar 1997 issue of MIT Technology Review. This version has greater technical detail and embedded links. , (Original article link).
Welcome to the MIT AI Lab Reversible Computing Home Page
21-Jan-2002 UniSci: Quantum Gravitational States Observed For First Time Citat: "...The researchers report seeing a minimum (quantum) energy of 1.4 picoelectron volts (1.4 x 10^-12 eV)..."
Big Bang Cosmology Meets an Astronomical Death By Paul Marmet Citat: "...Nor can Einstein's general theory of relativity be applied in a consistent manner to the Big Bang model. According to the model, when the universe was the size of an electron and was 10-^23 second old, it was clearly a black hole - a concentration of mass so great that its self-gravitation would prevent the escape of any mass or radiation. Consequently, according to Einsteinian relativity, it could not have expanded...."
Relativity FAQ: What causes Gravity? Citat: "...The world we live in consists of four dimensions, the three space dimensions and one that is not exactly time but is related to time (it is in fact time multiplied by the square root of -1)...."
Physics World, December 1999, Volume 12 Issue 12 Article 2: Quantum gravity presents the ultimate challenge to theorists Citat: "...Physics in the 20th century is founded on the twin pillars of quantum mechanics and the theory of relativity. However, in spite of the enormous successes of each theory individually, the two appear to be incompatible. This embarrassing contradiction at the very heart of theoretical physics remains one of the great outstanding challenges in science..."
The Quantum World: Review and discussion of implications of quantum theory, popular
article written by a physicist.
[mirror]
The Quantum World, EPR:- Spooky Connections
[mirror]
Citat: "...Quantum theory upset Einstein because it gave him nothing better
to grapple with than frustrating probabilities. In 1936, he got together
with Boris Podolsky and Nathan Rosen to create the "EPR paradox". It's
ironic that the spooky
EPR connection has now been used in the lab to teleport
photons, because the original reason for inventing the EPR paradox was
to show that one of the implications of quantum theory was so unacceptable
that it must be wrong or incomplete in some respect. What the EPR trio
couldn't accept was the idea that measuring a photon in one place could
have an instantaneous physical consequence somewhere else -- all because
quantum measurements are about probabilities..."
The Quantum World, Parallel Power - Computing
[mirror]
Citat: "...What would you get if you crossed a Bose-Einstein condensate with Schroedinger's
cat? One big, chilly cat? A litter of identical but indeterminate kittens?
In fact, no: you would get a quantum computer. But let's take that a little
more slowly..."
December 10, 1997 Science fact: Scientists achieve 'Star Trek'-like feat Citat: "...If the notion of entanglement leaves your head spinning, don't feel bad. Zeilinger said he doesn't understand how it works either. "And you can quote me on that," he said. . [ Prof. Anton Zeilinger ] ..."
DIY (Do It Yourself): Quantum Tunneling on Your Kitchen Table
Google Web directory: Quantum Mechanics
Quantum Mechanics and Bell's Inequality, Keith Mckenna, Department of Physics and Astronomy
NewScientist: Crossing the quantum frontier
Kansas State University, Department of Physics: Visual Quantum Mechanics
Does Gravity Travel at the Speed of Light?
Chris Hillman: Relativity on the World Wide Web
C. David Sherrill, School of Chemistry and Biochemistry, Georgia Institute of Technology: Citat: "...A Brief Review of Elementary Quantum Chemistry..."
The Everett Interpretation: many worlds FAQ
Caroline H Thompson, Department of Computer Science, University of Wales, Aberystwyth, UK: Citat: "...The Tangled Methods of Quantum Entanglement Experiments..."
xxx.uni-augsburg.de e-Print archive mirror: General Relativity and Quantum Cosmology (since 7/92)
The Physics of Quantum Information European Research Network, Citat: "...Research objectives: The network's research will make use of the most significant properties of quantum phenomena: the complementarity principle, the uncertainty principle, and the existence of entangled states. Recent developments in experimenting with individual quantum systems open up new fields of research: quantum computation, quantum cryptography, and quantum communication. These closely related fields investigate applications of the quantum physics of information coding, transmission and processing..."
Caltech - MIT - USC: Quantum Information and Computation QUIC
MAD Scientist Network: Re: Faster than light transmissions Citat: "...First of all you have to realize one central fact that lies pretty much at the basis of known physical theory: It is impossible to transmit information with a velocity that is greater than that of light! This stems from Special Relativity..."
IBM research: Quantum Teleportation
UniSci, 26-Nov-2001 Holograms Based On 'Spooky Action At A Distance' Citat: "...It's the interference of the possible paths that encodes the holographic image of the hidden object, which is very spooky indeed. ..."
Scientific American: "Beam Me Up" An experiment confirms that teleportation is possible--at least for photons. , Web archive mirror (Electronic Document Delivery) (Interferometry with Electrons and Ions)
Center for KvanteInformatik: Citat: "... CKI is a research center situated at the physics and computer science departments of University of Aarhus. Its purpose is to do application oriented and theoretical research in all aspects of quantum information processing, including as main research areas quantum cryptography and quantum computing...."
27. september 2001 Dansk gennembrud i kvanteforskningCitat: "...Kvantekommunikation og teleportation er rykket et skridt nærmere...Ph.d.-studerende Brian Julsgaard, forskningsadjunkt Alexander Kozhekin og professor Eugene Polzik har demonstreret det såkaldte "entanglement" af to objekter, som hver især består af omkring en trillion atomer...Dermed kan et objekts tilstand transporteres fra et sted til et andet - teleportation er en realitet, men endnu kun i lille målestok..."
Quantum Teleportation By Kenneth Chang ABCNEWS.com
Citat: "...What physicists at Caltech, Aarhus University in Denmark and the University
of Wales have accomplished is to take somethinga beam of light, in this
case and create a replica some distance away.
We claim this is the first bona fide teleportation, says Caltech physics
professor Jeff Kimble, one of the researchers. The advance wont lead to
Star Trek technology, but could help with sophisticated cryptography and
possibly ultra-powerful quantum computers..."
Teleportation DR artikel: Citat: "...Men for nyligt lykkedes det for en lille gruppe forskere her på Kvanteoptisk Laboratorium ved Århus Universitet at gennemføre verdens første teleportation - af laserlys...."
Lunar Institute of Technology (LIT) Library
SEDS: Students for the Exploration and Development of Space
Ingeniøren net: Hubble-teleskop slår øjnene op
Superluminal -- from Eric Weisstein's World of Physics
New Scientist: 16 September 02. Speed of light broken with basic lab kit
Markus Pössel: Faster-than-light [FTL] speeds in tunneling experiments: an annotated bibliography , German (Newer)
Dansk fysiker redder Einsteins teori Citat: "...Eksperimenter, der tyder på overlyshastighed, kan forklares ud fra fotonens upræcise fødested, mener fysikprofessor Ole Keller...."
Scientific American: Unlimited Light, Researchers make pulses that travel faster than light--sort of , Web archive mirror Citat: "...The result is the same pulse but advanced in time by a factor of 310-specifically, 62 nanoseconds better than the 0.2 nanosecond it takes for light to travel that distance in a vacuum. ...Wang plans to investigate several aspects of the superluminal group velocity, including trying to measure the velocity of energy transport (he suspects it will be bounded by the vacuum speed of light)..."
Artikel: Observation of Superluminal [=FTL] Behaviors in Wave Propagation
BBC News, 7 June, 2000: Faster than a speeding light wave
BBC Documentary: HORIZON --- The Time Lords Citat: "...Another broken taboo concerns sending messages faster than light. Breaking the light speed barrier is totally forbidden by Einstein, and all who believe in him, for moving beyond it would make time stand still. But that has not stopped a German Time Lord, physicist Gunter Nimtz, transmitting Mozart's 40th Symphony across his lab at 4.7 times the speed of light. Impossible, yes, but demonstrated on screen in HORIZON..."
NOVA #2612 transcripts: Time Travel , Nova list by topic
Science News: backward time travel
Ing 12/05/2000: Paa smuttur til en fjern galakse Citat: "...Ormehuller er genveje i universet. Hvis de altsaa findes..."
BBC News 12 April, 2000: Wormholes take on a new dimension Citat: "...New calculations suggest that wormholes large and stable enough to allow intergalactic travel really can exist..."
(Ian G. Moss): Newcastle Relativity and Quantum Fields , Hovedadresse
BBC News 12 May, 2000: Setting sail for the stars Citat: "...Nasa scientists are developing space sail technology to power a mission beyond the planets..."
NASA: Space Transportation Directorate (STD) Office
NASA: Status of "Warp Drive" Maturity - speculation
NASA Breakthrough Propulsion Physics Program
1997: The NASA Breakthrough Propulsion Physics Program
New Scientist: "The Physics of Star Trek": Could warp drive work?
Miguel Alcubierre: My warp drive paper
On the (un)likelihood of Interstellar Travel
FTL Travel: The Realities of an SF Cliche
Propulsion Systems, Engines and Launchers
Robert Stirniman's Antigravity Bibliography Citat: "...Electrogravitic Reference Files from Robert Stirniman..."
Relativity and FTL [=Superluminal motion] Travel Homepage
Chandra X-ray Observatory: Chandra Sky Map
Ing., 23.11.2002, Sort hul på ræs gennem galaksen Citat: "...GRO-J1655-40 er ikke det første sorte hul på rejse, som Mirabel har fundet. Sidste år fandt han et andet sort hul, som er på vej tværs igennem Mælkevejens baneplan, men det menes ikke at stamme fra en supernovaeksplosion....."
BBC News 19 November, 2002, Black holes on collision course Citat: "...For the first time scientists have seen two supermassive black holes existing together at the core of the same galaxy...."
NASA News: November 6, 2000: Catching a galactic football: Chandra examines Cygnus A
BBC News Friday, 10 November, 2000: Lone neutron star speeds through space
Ing 13/10/2000: Vandrende planeter fundet i universet
BBC News 26 April, 2000: Universe proven flat
BBC News Monday, 8 May, 2000: Black hole search begins Citat: "...They [black holes] can be more than 100 million times larger than the mass our Sun, up to 10% of a galaxy's mass...."
BBC News 14 January, 2000: Lone drifter black holes discovered, six times heavier than the Sun
BBC News 14 January, 2000: Chandra solves cosmic X-ray mystery Citat: "...Each of them probably harbours a massive black hole at its core that produces X-rays as gas is pulled toward it at nearly the speed of light..."
Ing 10/02/00: Sort hul fundet i vores baghave, Citat: "...kun 1600 lysår fra Jorden..."
BBC News November 17, 1999: X-rays mark galactic collision: Citat: "...distant galaxy 3C295 shows a titanic explosion surrounded by a vast cloud of gas at a temperature of fifty million degrees... These X-rays are most likely due to matter falling into a supermassive black hole..."
BBC News August 17, 1999: Black hole detected swallowing matter, Citat: "...buried in the typical emission spectrum was a "red-shifted" absorption feature, also from iron atoms..."
BBC News April 14, 1999: New black holes discovered
BBC News March 3, 1999: Hubble reveals stellar traffic jam Citat: "...The stars are piling up on one side of a super-massive black hole, deep in the heart of the nearest galaxy to our own Milky Way ...The galaxy in question is the Andromeda galaxy, also known as M31..."
BBC News June 18, 1998: Hubble finds huge black hole: Citat: "...galaxy NGC 7052, 300 million times more massive than our sun..." (mirror)
Ing Uge 25/1998: Sort hul spiser en galakse, Citat: "...Kentaur-A galaksen, også kaldet NGC 5128..."
New Scientist, 28 June 1997: "Light's spooky connections set distance record" , Web archive mirror: "Light's spooky connections set distance record"
Physics World,
March 1998 Volume 11 Issue 3 Article 9, Anton Zeilinger: Fundamentals
of quantum information
,
Web archive mirror
The fact that
information is physical means that the laws of quantum mechanics can be
used to process and transmit it in ways that are not possible with existing
systems.
Citat:
"...
Photons, electrons, atoms, quantum dots and so on can all be used as
qubits. It is also possible to use both internal states, such as the energy
levels in an atom, and external states, such as the direction of propagation
of a particle, as qubits
(see [Web archive mirror:] table
).
...
Entanglement describes correlations between quantum systems that are
much stronger than any classical correlations.
...
Although it was shown that GHZ states lead to violent contradictions
between a local realistic view of the world and quantum mechanics, it recently
turned out that such states are significant in many quantum-information
and quantum-computation schemes.
...
For example, if we consider 000 and 111 to be the binary representations
of "0" and "7", respectively, the GHZ state simply represents the coherent
superposition (1/?2)( "0"? + "7"?). If a linear quantum computer has such
a state as its input, it will process the superposition such that its output
will be the superposition of the results for each input. This is what leads
to the potentially massive parallelism of quantum computers.
...
How
to entangle photons
...
The
entanglement of photons over distances as great as 10 km has now been demonstrated
at the University of Geneva
[, Web archive mirror]
, so teleportation is expected to work over similar distances.
...
As mentioned above, an important feature is that teleportation provides
no information whatsoever about the state being teleported. This means
that any quantum state can be teleported. In fact, the quantum state does
not have to be well defined; indeed, it could even be entangled with another
photon. This means that a Bell-state measurement of two of the photons
? one each from two pairs of entangled photons ? results in the remaining
two photons becoming entangled, even though they have never interacted
with each other in the past (see right [
Entanglement
swapping ]).
..."
The
New York Times Company: Signal Travels Farther and Faster Than Light:
Citat: "...
The idea behind Gisin's
[
Professor Nicolas Gisin ]
experiment was not new. Since the
1970s, physicists have been testing a prediction of quantum theory that
"entangled" particles continue to communicate with each other instantaneously
even when very far apart.
...
The connections that persist between distant but entangled particles
are "one of the deep mysteries of quantum mechanics," Chiao
[
Professor Raymond Y. Chiao ]
said in an interview. "These connections are a fact of nature proven by experiments,
but to try to explain them philosophically is very difficult," he said."
...
One of the weird aspects of quantum mechanics is that something can
simultaneously exist and not exist; if a particle is capable of moving
along several different paths, or existing in several different states,
the uncertainty principle of quantum mechanics allows it to travel along
all paths and exist in all possible states simultaneously. However, if
the particle happens to be measured by some means, its path or state is
no longer uncertain. The simple act of measurement instantly forces it
into just one path or state.
Physicists call this a "collapse of the wave function." The amazing thing is that if just one particle in an entangled pair is measured, the wave function of both particles collapses into a definite state that is the same for both partners, even separated by great distances.
Among several proposed explanations of all this is the "many worlds" hypothesis [ 1957 Everett paper på dansk Serge A. Winitzki 1993: Bemærkninger til Mange-Verdener Tolkningen Google: Quantum Mechanics Interpretations ]: the notion that for every possible pathway or state open to a particle, there is a separate universe. For each of 10 possible pathways a quantum particle might follow, for example, there would exist a separate universe.
Since the 1970s, Dr. John F. Clauser of the University of California
at Berkeley, Dr. Alain
Aspect at the Institut des Optics in Orsay, France, and others have
been experimenting with pairs of entangled particles.
...
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 [Tunneling speed / Superluminal motion paper], 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."
..."
På Dansk: "Materiens og lysets dualitet" oversat fra: B.-G. Englert, M. O. Scully, and H. Walther, The Duality in Matter and Light, Sci. Am., Dec., 1994, pp. 56-61.
New
Scientist, 6 March 1999: "An end to uncertainty"
[, Web archive mirror]
, (Kopi
reference: Uncertainty and Quantum Entanglement New Sci 6 Mar 99)
Citat: "...
They have been labouring under the delusion that what makes quantum
theory so weird is its inherent uncertainty, or fuzziness, but in fact
another feature of the quantum world, a phenomenon called entanglement,
is at the root of it all.
...
The essence of the new experiment was proposed in 1991 by
Marlan Scully,
Berthold-Georg Englert and Herbert
Walther of the Max Planck Institute for Quantum Optics in Garching,
Germany. A two-slit experiment works with any kind of quantum particle.
But they suggested that atoms might offer an advantage. An atom has a variety
of different internal states: a lowest energy ground state and a series
of higher energy or "excited" states. And these different states, they
reckoned, could be used to record the atom's path.
"Much of our experiment is based on that proposal," says Rempe. In the 1980s, physicists devised ways to cool atoms to within a hair's breadth of absolute zero using laser light. "Scully and his colleagues came up with the idea because they could use cold atoms," says Rempe. The point about cold atoms is that they have long wavelengths, which makes their interference patterns relatively easy to observe.
Still, no one could make the experiment work until last year, when Rempe and his colleagues managed it with a few clever tricks. They didn't actually send atoms through slits in a solid barrier, but instead split a beam of cold rubidium atoms using thin barriers of pure laser light (see Diagram, p 28). The beams overlap, but travel along slightly different paths, A and B. As in the classic two-slit experiment, the two beams then combine to create an interference pattern.
But then Rempe and his colleagues looked to see which path the atoms
followed. The atoms going down path A weren't interfered with, but those
on path B were tweaked into a higher energy state by a pulse of microwaves.
So the atoms, in their internal states, kept a record of which way they
had gone.
["Origin
of quantum-mechanical complementarity probed by a `which-way' experiment
in an atom interferometer " S.Dürr, T.Nonn, and G.Rempe Nature, 395,
33-37 (1998) *PDF
fil adresse*]
The payoff is impressive. The microwaves have hardly any momentum of their own, so they can cause little change to the atom's momentum--certainly not enough to smear away the interference pattern.
Yet the quantum world's wave-particle balancing act still works. With the microwaves turned off, the interference fringes appear. Turn them on, so that you can tell which way the atoms went, and the fringes suddenly vanish. "Everyone believes that when an interference pattern is lost, it happens because a measuring device delivers random kicks to the particles. But there are no random kicks in our experiment," says Rempe. At least, none worth mentioning. Rempe estimates that, at worst, the microwaves deliver momentum kicks ten thousand times too small to destroy the interference fringes. The uncertainty principle isn't proved wrong, because in this setup the measurement of position is very imprecise, but it can't explain the results.
So what's going on? Is the central story of quantum theory just that--a story? Or is this one experiment merely an unimportant curiosity? At the University of Cambridge, physicist Yu Shi is trying to find out. Motivated by Rempe's experiment, he has taken another look at the early thought experiments in which Bohr [britannica , Biography ] "defeated" Einstein [britannica]. And he has come to be less than impressed by Bohr's analyses.
Each of these thought experiments was designed to portray a particular case in which the quantum world refuses to reveal both its wave-like and its particle-like faces at the same time. And in each case, Shi points out, Bohr discussed the physics using only the simple Planck and de Broglie relations. These are the rudimentary equations that connect a particle's momentum and energy to its wavelength and frequency.
So Shi has reanalysed the thought experiments using the rigorous equations of quantum theory, which give the fullest description possible of a quantum particle. And he has found that despite everything Bohr said, the uncertainty principle never has anything to do with destroying the interference. "People think that Bohr was right, and Einstein was wrong," he says, "but this is far from the truth. Bohr's idea that a momentum kick destroys the interference is wrong."
Shi's point is that although momentum kicks seem to explain the classic
two-slit experiment, it is just a happy coincidence of numbers. There is
a far deeper mechanism at work: it is the getting of path information itself
that spoils the interference, says Shi. Forget all vague ideas of uncertainty,
and look instead to the far more precise notion of "quantum entanglement".
..."
Juli 2007