Alcubierre-drev

Alcubierre-drevets koncept, som viser de to rumtidsområder foran og bagved det centrale område.
Rumskib med Alcubierre-drev (rød plet) som passerer jorden.

Et Alcubierre-drev er et hypotetisk warp-drev, som er i stand til at flytte et rumfartøj gennem rumtiden med hastigheder større end lysets (dog ikke lokalt) ved at krumme rumtid, således at rummet foran drevet trækkes sammen og rummet bagved drevet udvides, hvormed en warpbobbel, en slags bølge, skabes. Dette giver ikke fartøjet i sig selv fremdrift, men bevæger i stedet selve rummet omkring fartøjet. Alcubierre-drevet ville være i stand til at flytte fartøjet med overlyshastighed samtidig med at overholde Einsteins relativitetsteori.[1]

I 1994 foreslog den mexikanske fysiker Miguel Alcubierre en metode til at strække rumtiden i en bølgebevægelse, som teoretisk ville trække rumtiden sammen foran et rumfartøj og få rumtiden bagude til at udvide sig.[2] Rumfartøjet ville ride på denne bølge inde i warp-boble–området som vist i den illustrerede flade rumtid. Da rumfartøjet ikke bevæger sig indeni i denne boble, men bliver ført med rumtidsområdet, som selv bevæger sig, vil relativistiske effekter såsom tidsdilation ikke finde sted, som de vil med rumfartøjer, som bevæger sig med høj hastighed gennem en flad rumtid.

Kvantemekanik forbyder ikke “rumtidsgenveje” baseret på Alcubierre-drev.[3]

En artikel af José Natário offentliggjort i 2002, viste at det ville være umuligt for rumfartøjet at sende signaler til warp-boble forenden, hvilket betyder at besætningen ikke ville kunne styre eller stoppe rumfartøjet.[4]

Harold G. White mente i 2012 at man kunne realisere Alcubierre drevet med betydeligt mindre masse end tidligere beregnet.[5]

I år 2021 har to forskere Alexey Bobrick og Gianni Martire fundet en matematisk løsning på et Alcubierre-drev, som ikke har behov for negativ energi. Den ene artikel (Alexey Bobrick og Gianni Martire) kan teoretisk kun opnå under-lyshastighed med sin løsning - og den anden artikel (Erik Lentz) kan teoretisk opnå overlyshastighed.[6][7][8]

Se også

Kilder/referencer

  1. ^ Defense Intelligence Reference Document. Acquisition Threat Support: 2 April 2010, Warp Drive, Dark Energy, and the Manipulation of Extra Dimensions Citat: "...In recent years, however physicists have discovered two loopholes to Einstein's ultimate speed limit: the Einstein-Rosen bridge (commonly referred to as "wormhole") and the warp drive. Fundamentally, both ideas involve manipulation of spacetime itself in some exotic way that allows for faster-than-light (FTL) travel...The warp drive-the main focus this paper-involves local manipulation of the fabric of space in the immediate vicinity of a spacecraft. The basic idea is to create an asymmetric bubble of space that is contracting in front of the spacecraft while expanding behind it...", backup
  2. ^ Alcubierre, Miguel (1994). "The warp drive: hyper-fast travel within general relativity". Class. Quant. Grav. 11: L73-L77. doi:10.1088/0264-9381/11/5/001. See also the"eprint version". arXiv. Hentet 23. juni 2005., og også på iop.org
  3. ^ S. Krasnikov (2003). "The quantum inequalities do not forbid spacetime shortcuts". Physical Review D. 67: 104013. doi:10.1103/PhysRevD.67.104013. Se også"eprint version". arXiv.
  4. ^ Warp drive with zero expansion, backup
  5. ^ 26. sep 2012, ing.dk: Amerikansk forsker skaber håb om warp-drive til rumskibe Citat: "...foreslået ændringer til Miguel Alcubierres koncept. Han konkluderer, at konceptet måske kunne realiseres med en række modifikationer..."
  6. ^ May 16, 2021, scitechdaily.com: Warp Drives and Negative Energy: Physicists Give Chances of Faster-Than-Light Space Travel a Boost Citat: "...Two recent papers – one by Alexey Bobrick and Gianni Martire and another by Erik Lentz – provide solutions that seem to bring warp drives closer to reality...Bobrick and Martire realized that by modifying spacetime within the bubble in a certain way, they could remove the need to use negative energy. This solution, though, does not produce a warp drive that can go faster than light. Independently, Lentz also proposed a solution that does not require negative energy. He used a different geometric approach to solve the equations of General Relativity, and by doing so, he found that a warp drive wouldn’t need to use negative energy. Lentz’s solution would allow the bubble to travel faster than the speed of light...", backup
  7. ^ Introducing physical warp drives 2021 Class. Quantum Grav. 38 105009: Alexey Bobrick and Gianni Martire, backup
  8. ^ 2021 Class. Quantum Grav. 38 075015: Breaking the warp barrier: hyper-fast solitons in Einstein–Maxwell-plasma theory, backup
  • Lobo, Francisco S. N.; & Visser, Matt (2004). "Fundamental limitations on 'warp drive' spacetimes". Class. Quant. Grav. 21: 5871-5892. doi:10.1088/0264-9381/21/24/011.{{cite journal}}: CS1-vedligeholdelse: Flere navne: authors list (link) See also the"eprint". arXiv. Hentet 23. juni 2005.
  • Hiscock, William A. (1997). "Quantum effects in the Alcubierre warp drive spacetime". Class. Quant. Grav. 14: L183-L188. doi:10.1088/0264-9381/14/11/002. See also the"eprint". arXiv. Hentet 23. juni 2005.
  • Berry, Adrian (1999). The Giant Leap: Mankind Heads for the Stars. Headline. ISBN 0-7472-7565-3. Apparently a popular book by a science writer, on space travel in general.
  • T. S. Taylor, T. C. Powell, "Current Status of Metric Engineering with Implications for the Warp Drive," AIAA-2003-4991 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Huntsville, Alabama, July 20-23, 2003
  • H. E. Puthoff, "SETI, the velocity-of-light limitation, and the Alcubierre warp drive: an integrating overview," Physics Essays 9, 156-158 (1996).

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Alcubierre.png
Forfatter/Opretter: AllenMcC., Licens: CC BY-SA 3.0
Warp field according to the Alcubierre drive.
Alcubierre drive passing in front of Earth.webm
Forfatter/Opretter: SXS Collaboration, Licens: CC BY 2.0
"What it would look like if an Alcubierre drive were to pass in front of Earth, as viewed by an observer looking at Earth. The space ship in this video is a red sphere moving from left to right at a speed of 1.5 times the speed of light.

We see some interesting phenomena due to the fact that the ship is moving faster than light. When the ship is far off to the left, the radial velocity of the ship relative to the observer is greater than the speed of light. Due to this, the ship is not seen until the radial velocity of the ship is less than the speed of light. Once this happens, we see two images of the ship, one image moving left and one to the right. We also see significant gravitational lensing of the Earth due to the Alcubierre bubble.

The image of the ship stretches out and slows down as it moves to the right of the video. This is again a consequence of the ship moving faster than the speed of light, but the ship is moving away from the observer as it is emitting light.

Some parameters of the system:

  • The metric can be found on this page: https://en.wikipedia.org/wiki/Alcubierre_drive
  • The velocity is a constant 1.5c
  • Bubble thickness: sigma = 4/3
  • Bubble radius: R = 2
  • Red spherical ship at the center of the bubble
  • Camera is 5 bubble radii from the ship's closest approach
  • Camera horizontal aperture angle is 135 degrees

The same setup can be viewed with a grid background instead of an Earth background here: https://www.youtube.com/watch?v=ugvsiT0b7pw

To further explore the effects of a faster than light ship, see: https://www.youtube.com/watch?v=JP7ol...​

For more information, see http://www.black-holes.org/lensing"