Gravity assist for "fuld skrue"

22/03 2012 Nogle stjerner og planeter slynges simpelthen ud af f.eks. galaksen Mælkevejen - ud i det "intergalaktiske flipperspil":

Harvard-Smithsonian Center for Astrophysics (2012, March 22). Runaway planets zoom at a fraction of light speed. ScienceDaily:
http://www.sciencedaily.com/releases/2012/03/120322113604.htm
...

Video: Boomerang in zero gravity

04/02 2012 Målet med denne video er at vise, at gravitation ikke er nødvendig for at en boomerang kan komme tilbage til udgangspunktet:

Boomerang in zero gravity:
http://www.youtube.com/watch?v=q2ozs0tPr4k

Gåde: European Space Agency (2006, March 25). Anti-gravity Effect? Gravitational Equivalent Of A Magnetic Field Measured In Lab. ScienceDaily

04/02 2012 http://www.sciencedaily.com/releases/2006/03/060325232140.htm
Citat: "...
Although just 100 millionths of the acceleration due to the Earth's gravitational field, the measured field is a surprising one hundred million trillion times larger than Einstein's General Relativity predicts
...
"We ran more than 250 experiments, improved the facility over 3 years and discussed the validity of the results for 8 months before making this announcement
...
"If confirmed, this would be a major breakthrough," says Tajmar, "it opens up a new means of investigating general relativity and it consequences in the quantum world."
..."

frame-dragging; Gravitomagnetisme bekræftet

04/02 2012 20 October 2004 Spinning Earth twists space.
Laser measurements confirm Einstein's general theory of relativity.
http://www.nature.com/news/2004/041018/full/041018-11.html
The Search for Frame-Dragging:
http://www.phys.lsu.edu/mog/mog10/node9.html

http://en.wikipedia.org/wiki/Frame_dragging

20 October 2004 Relativity passes latest test:
http://physicsweb.org/articles/news/8/10/12/1

24.10.2004 Lasermålinger bekræfter Einstein-teori.
Forskere har målt Einsteins teorier om objekters skævvridning af rumtiden. Dermed er en af fysikerens sidste forudsigelser om den generelle relativitetsteori bekræftet.
http://ing.dk/artikel/59036
Citat: "...
Men i seneste nummer af Nature siger to italienske forskere nu, at de så godt som har bevist eksistensen af frame-dragging, som fænomenet hedder på engelsk.
...
»Deres resultater er det første rimeligt præcise forsøg på at måle gravitomagnatisme,« vurderer fysikeren Neil Ashby fra University of Colorado.
..."

GP-B STATUS UPDATE — May 4, 2011:
http://einstein.stanford.edu/highlights/status1.html
Citat: "...
The black ellipse shows the weighted average of these measurements for all four gyroscopes combined. The black star in the center of the black ellipse is the actual location of Einstein's predicted geodetic and frame-dragging values.
..."

Apr 16, 2008, Quasar tests general relativity to the limit

04/02 2012 Apr 16, 2008, Quasar tests general relativity to the limit:
http://physicsworld.com/cws/article/news/33818
Citat: "...
based on refined models and years spent monitoring OJ287, Valtonen and others were able to predict the date on which the next bright pulse should appear: 13 September 2007, give or take a day or two.
...
Furthermore, the work suggests that the binary system is losing energy by emitting gravitational waves — a key prediction of Einstein's theory that is yet to be verified directly. When this emission is not included in the model, the quasar outburst is predicted to occur 20 days later, providing indirect support for gravitational waves.
...
a good target for the Laser Interformeter Space Antenna (LISA) — especially in the period 2016–2019 when the next big outbursts are due.
..."

En kvasar er en type af aktiv galakse (måske er en kvasar blot en aktiv galakse set fra en bestemt vinkel):
http://da.wikipedia.org/wiki/Aktiv_galakse
http://en.wikipedia.org/wiki/Active_galactic_nucleus
Citat: "...
AGN terminology is often confusing, since the distinctions between different types of AGN sometimes reflect historical differences in how objects were discovered or initially classified, rather than real physical differences.
...
LINERs...Seyfert galaxies...Radio-quiet quasars/QSOs...'Quasar 2s'...Radio-loud quasars...'Blazars' (BL Lac objects and OVV quasars)...Radio galaxies
..."

Kvasar:
http://en.wikipedia.org/wiki/Quasar

Einstein relativitetsteori testes dagligt af GPS

04/02 2012 American Physical Society (2009, August 24). Rewriting General Relativity? Putting A New Model Of Quantum Gravity Under The Microscope. ScienceDaily:
http://www.sciencedaily.com/releases/2009/08/090824115758.htm
Citat: "...
The theory, which Einstein developed in the early 20th century, says that matter curves spacetime, and it is this curvature which deflects massive bodies – an effect that we interpret as the influence of gravity.
The theory has been tested to extremely high accuracy and without it, our satellite global positioning system would be off by about 10 km per day.
..."

Svar til "spørge-Jørgen"

04/02 2012 Ask the Astronomer:
http://www.astronomycafe.net/qadir/qanda.html

Special & General Relativity Questions and Answers:
http://einstein.stanford.edu/content/relativity/qanda.html

If gravity is a 'wave' of energy, does the concept of frequency have any meaning?
http://einstein.stanford.edu/content/relativity/q1618.html

How are electromagnetism and space-time related, and can electromagnetic fields exert a force on space-time?
http://einstein.stanford.edu/content/relativity/q1347.html

How does general relativity incorporate rotation?
http://einstein.stanford.edu/content/relativity/q1779.html

Don't objects steadily evaporate over time by emitting gravity waves?:
http://einstein.stanford.edu//content/relativity/q2374.html
What happens to rotating solid objects in relativity theory?
http://einstein.stanford.edu/content/relativity/q1973.html

Is the gravity of distant objects the cause of inertia?
http://einstein.stanford.edu/content/relativity/a11195.html
Citat: "... We do not really know. General relativity and Mach's Principle seem to suggest that this is true...."

What is Gravity Probe B?
Physicists and engineers at Stanford University have created a wide range of exotic technologies to perform a satellite experiment that will probe the very foundations of space time.
http://einstein.stanford.edu/content/story_of_gpb/gpbsty1.html
Stanford: The Geodetic Effect: Measuring the Curvature of Space-time
http://einstein.stanford.edu/content/story_of_gpb/gpbsty3.html
"... Third, most important, Gravity Probe B investigates the gravitational action of moving matter. Matter moving through space-time can be thought of as creating a new force -- gravitomagnetism -- which John Wheeler, dean of relativists, describes as being "as different from ordinary gravity as magnetism is from electricity." The frame-dragging measurement detects this force and fixes its scale.
[]
Commenting on its unverified status, Wheeler has said "It is hard to imagine a science so exposed for lack of evidence on a force so fundamental to the scheme of physics."..."

What is centrifugal force?

04/02 2012 http://www.thekeyboard.org.uk/What%20is%20centrifugal%20force.htm
Citat: "...
Centrifugal force is not fictitious, it is a real force [Rettere: rumtidskrumning? eller gravitomagnetisme?]
..."

Double pulsar find to test relativity

04/02 2012 14.01.2004, Double pulsar find to test relativity:
http://www.innovations-report.com/html/reports/physics_astronomy/report-24752.html
Citat: "...
Using the 64-m CSIRO Parkes radio telescope in New South Wales, Australia, the team recently detected the first system of two pulsars orbiting each other - the only system of its kind found so far among the 1400-plus pulsars discovered in the last 35 years.
...
The two stars will gradually draw closer together, with the orbital energy being lost from the system in the form of gravitational radiation.
..."

March 2005 Gravitational labs in the sky.
The first-ever double-pulsar system was discovered by radio astronomers two years ago and has provided the sternest test of general relativity to date.
http://physicsweb.org/articles/world/18/3/6/1
http://physicsworldarchive.iop.org/index.cfm?action=summary&doc=18%2F3%2Fphwv18i3a27%40pwa-xml&qt=
Citat: "...
But few, if any, of these discoveries compare to that of PSR J0737-3039.
..."

14th September 2006, manchester.ac.uk: General Relativity survives gruelling pulsar test - Einstein at least 99.95% right!:
http://www.jodrellbank.manchester.ac.uk/news/2006/einstein/
Citat: "...the double pulsar system should lose energy causing the two neutron stars to spiral in towards each other by precisely the amount that we have observed - thus our observations give an indirect proof of the existence of gravitational waves [as predicted by Einstein]..."

Hvad er en Pulsar?:
http://da.wikipedia.org/wiki/Pulsar

Experimental Gravitational Physics Using Drag-Free Satellites

04/02 2012 http://www.dragfreesatellite.com/
Citat: "...
Drag-Free Satellites offer an environment with the lowest disturbing forces in nature. A properly designed Drag-Free-Satellite proof mass is uncoupled from the rest of the Universe to a remarkable degree.
..."

The Relativity Gyro: Prepublication Version (PDF):
http://www.dragfreesatellite.com/relgyro2.1.pdf

Hvem tester gravity-assist teoretisk med tendex lines og vortex lines?

04/02 2012 Der er sikkert et eller nogle uopdagede fænomener, som venter på at blive opdaget? I værste tilfælde kan man nøjes med at blive klogere:

Konservatisme i datidens NASA JPL, lige ved at forhindre Gravity-assist-anvendelsen! Gravity-assist-ideen er kun 50 år gammel:

gravityassist.com: The Creation of a new Theory of Space Travel -- Gravity Propelled Space Travel:
http://www.gravityassist.com/#_Toc127789951
Citat: "...
When Minovitch presented it to JPL in the form of 47 page technical paper dated August 23, 1961, it was dismissed by the head of JPL’s Trajectory Group as impossible
...
How could a young graduate student in mathematics and physics who never studied the problem of space propulsion, space travel or astrodynamics before the summer of 1961 ever invent a completely new theory of space travel
..."

Og Gravity assist bliver og er blevet brugt!

( fra http://da.wikipedia.org/wiki/Gravity_assist )

NASA: JPL:
http://da.wikipedia.org/wiki/Jet_Propulsion_Laboratory

Hvem tester ormehuller teoretisk med tendex lines og vortex lines?

04/02 2012 Ormehuller:
http://da.wikipedia.org/wiki/Ormehul

Med designopskrift ;-) :

Eric W. Davis, Ph.D.: Wormhole-Stargates: Tunneling Through The Cosmic Neighborhood (pdf):
http://web.archive.org/web/20061010170245/www.nidsci.org/pdf/davis_mufon2001.pdf
Citat: "...2.5 Designing a Stargate..."

Hvem tester et Alcubierre drive teoretisk med tendex lines og vortex lines?

04/02 2012 Alcubierre drive:
http://da.wikipedia.org/wiki/Alcubierre_drive

Alcubierres ide fra forrige årtusind er endnu ikke tilbagevist. Men der er et par praktiske problemer, der lige skal løses. ;-)

Quantum inequalities do not forbid spacetime shortcuts:
http://prd.aps.org/abstract/PRD/v67/i10/e104013
Citat: "...
A class of spacetimes (comprising the Alcubierre bubble, Krasnikov tube, and a certain type of wormhole) is considered that admits “superluminal travel” in a strictly defined sense. Such spacetimes (they are called “shortcuts” in this paper)
...
I argue that the spacetimes of this type may not be unphysical at all.
[]
By explicit examples I prove that
[]
(1) the relevant quantum inequality does not (always) imply large energy densities,
[]
(2) large densities may not lead to large values of Etot-, and
[]
(3) large Etot- being physically meaningless in some relevant situations does not necessarily exclude shortcuts.
..."

18. jan 2011 Derfor starter din bilmotor: Der er relativistiske effekter på spil

04/02 2012 http://ing.dk/artikel/115646
Citat: "...
Samlet set viser de detaljerede beregninger, at 1,7 – 1,8 volt af spændingsforskellen på 2,1 volt i et blybatteri skyldes relativistiske effekter.
...
Og så slutter de artiklen af med disse ord: ”Finally, we note that cars start due to relativity”.
..."

California Institute of Technology (2011, April 11). Physicists discover new way to visualize warped space and time. ScienceDaily

04/02 2012 http://www.sciencedaily.com/releases/2011/04/110411092750.htm
Citat: "...
When black holes slam into each other, the surrounding space and time surge and undulate like a heaving sea during a storm. This warping of space and time is so complicated that physicists haven't been able to understand the details of what goes on -- until now.
...
have developed conceptual tools they've dubbed tendex lines and vortex lines.

Using these tools, they have discovered that black-hole collisions can produce vortex lines that form a doughnut-shaped pattern, flying away from the merged black hole like smoke rings.
[]
[Bemærk: Et stykke væk fra de storte huller vil gravidimserne "stråle væk" med ca. lysets hastighed]
The researchers also found that these bundles of vortex lines -- called vortexes -- can spiral out of the black hole like water from a rotating sprinkler.
...
Tendex and vortex lines describe the gravitational forces caused by warped space-time. They are analogous to the electric and magnetic field lines that describe electric and magnetic forces.
...
In either case -- doughnut or spiral -- the outward-moving vortexes and tendexes become gravitational waves -- the kinds of waves that the Caltech-led Laser Interferometer Gravitational-Wave Observatory (LIGO) seeks to detect.
...
[Det må kunne benyttes til rumfart?:]
The recoil is so strong that it can throw the merged hole out of its galaxy. [!]
...
"Though we've developed these tools for black-hole collisions, they can be applied wherever space-time is warped," says Dr. Geoffrey Lovelace, a member of the team from Cornell.
..."


5. sep 2010, Hvirvler i rumtiden omkring sorte huller overrasker forskerne.
En af verdens førende specialister i gravitationsbølger, Kip Thorne, har opdaget et hidtil ukendt fænomen omkring sorte huller. Stephen Hawking finder det yderst interessant.
http://ing.dk/artikel/112358
Citat: "...
Beregninger foretaget inden for de seneste par måneder viser dog, at et roterende sort hul danner to hvirvler i rumtiden, der udspringer for henholdsvis nordpolen og sydpolen, således at den ene hvirvel roterer med uret og den anden mod uret.
...
Støder to sorte huller sammen og danner et nyt hul, kan faconen af det sorte hul ændres fra en kugle til noget, der minder om en amerikansk football, og antallet af rumtids-hvirvler bliver fire.
..."



Med illustration:

13 April 2011, 'Tendex' lines help visualise black holes:
http://www.newscientist.com/article/dn20379-tendex-lines-help-visualise-black-holes.html
Citat: "...
The lines come in two varieties that capture two key properties of warped space-time.

One set describes the stretching and compressing forces that can rip apart and crush objects that venture near black holes. The team calls them tendex lines, based on the Latin word tendere, which means to stretch.

The other set of lines, called vortex lines, represent the twisting effects of warped space-time that would wring an object like a towel.
..."

Feb 17, 2010 Gravity's effect on time confirmed

04/02 2012 http://physicsworld.com/cws/article/news/41740
Citat: "...
Physicists in the US and Germany have used two fundamental tenets of quantum mechanics to perform a high-precision test of Einstein's general theory of relativity. The researchers exploited wave-particle duality and superposition within an atom interferometer to prove that an effect known as gravitational redshift – the slowing down of time near a massive body – holds true to a precision of seven parts in a billion.
..."

Gravity is an emergent force rather than a universal fundamental interaction?

04/02 2012 University of York (2011, August 10). Escaping gravity's clutches: Information could escape from black holes after all, study suggests. ScienceDaily:
http://www.sciencedaily.com/releases/2011/08/110810215342.htm
Citat: "...
the study by Prof. Samuel Braunstein and Dr. Manas Patra suggests that information could escape from black holes after all.

The implications could be revolutionary, suggesting that gravity may not be a fundamental force of nature.
...
Dr. Patra adds: "We cannot claim to have proven that escape from a black hole is truly possible, but that is the most straight-forward interpretation of our results. Indeed, our results suggest that quantum information theory will play a key role in a future theory combining quantum mechanics and gravity."
..."


Aug 15, 2011 Information paradox simplified:
http://physicsworld.com/cws/article/news/46848
Citat: "...
Their work also supports a controversial theory proposed last year that suggests that gravity is an emergent force rather than a universal fundamental interaction.
...
At the turn of this century, Maulik Parikh of the University of Utrecht in the Netherlands, together with Frank Wilczek of the Institute of Advanced Study in Princeton, US, showed how information could leak away from a black hole.
..."

eLISA/NGO

04/02 2012 NASA/Jet Propulsion Laboratory (2010, November 28). Tuning an 'ear' to the music of gravitational waves. ScienceDaily:
http://www.sciencedaily.com/releases/2010/11/101128220203.htm
Laser Interferometer Space Antenna

eLISA/NGO is a new concept for observing gravitational waves in space:
http://elisa-ngo.org/
Citat: "...
eLISA/NGO will open the gravitational wave window in space and measure gravitational radiation over a broad band of frequencies, from about 0.1 mHz to 100 mHz, a band where the Universe is richly populated by strong sources of gravitational waves.

eLISA/NGO consists of one mother- and two daughter spacecraft separated by a distance of 1 Mio km, forming the first Michelson interferometer in space.
..."

GEO 600?

04/02 2012 What is GEO 600?:
http://www.geo600.uni-hannover.de/geo600/project/home.html
Citat: "...
GEO 600 is a laserinterferometric detector for gravitational waves. It is basically a Michelson interferometer with 600 m armlength and dual recycling.
..."
Klik for meget mere...

Report disputes Lunar Laser Ranging

04/02 2012 http://www.upi.com/Science_News/2007/06/01/Report-disputes-Lunar-Laser-Ranging/UPI-73401180749392/
Citat: "...
A Missouri physicist says the Lunar Laser Ranging technique used to detect gravitomagnetic fields is ineffective.
..."

Lawrence Berkeley National Laboratory (2003, June 19). Berkeley Lab Physicist Challenges Speed Of Gravity Claim. ScienceDaily

04/02 2012 http://www.sciencedaily.com/releases/2003/06/030619075759.htm
Citat: "...
Samuel argues that Kopeikin erred when he based his calculations on Jupiter's position at the time the quasar's radiowaves reached Earth rather than the position of Jupiter when the radiowaves passed by that planet.
..."

University of Nottingham (2012, January 4). Magnetically levitated flies offer clues to future of life in space. ScienceDaily

04/02 2012 http://www.sciencedaily.com/releases/2012/01/120104133201.htm
Citat: "...
Diamagnetic levitation doesn't balance gravity as perfectly as 'real' weightlessness does in space, but diamagnetic levitation can be used to see which experiments are suitable and interesting to perform in space before spending money on a space launch.
..."

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