Editing Warp drive (section)

== Einstein's space warp and real-world physics ==
[[File:Lorentz factor.svg|thumb|upright=1|[[Lorentz factor]] {{math|γ}} as a function of velocity. Its initial value is 1 (when {{nobr|''v'' {{=}} 0}}); and as velocity approaches the speed of light {{nobr|(''v'' → ''c'')}} {{math|γ}} increases without bound {{nobr|({{math|γ}} → ∞)}}.]]
Einstein's theory of [[special relativity]] states that speed of light travel is impossible for material objects that, unlike [[photon]]s, have a non-zero rest mass. The problem of a material object exceeding light speed is that an infinite amount of kinetic energy would be required to travel at exactly the speed of light. Warp drives are one of the science-fiction tropes that serve to circumvent this limitation in fiction to facilitate stories set at galactic scales.<ref>{{Cite web|title=SFE: Faster Than Light|url=https://sf-encyclopedia.com/entry/faster_than_light|access-date=2021-11-10|website=sf-encyclopedia.com}}</ref> However, the concept of space warp has been criticized as "illogical", and has been connected to several other [[rubber science]] ideas that do not fit into our current understanding of physics, such as the [[Teleportation|transporters]] and [[Replicator (Star Trek)|replicators]] in [[Star Trek]], [[Anti-gravity|antigravity]] or [[negative mass]].<ref name=":0" />

Some argue that these effects mean that although it's not possible to travel faster than the speed of light, both space and time "warp" to allow travelling the distance of one light year, in less than a year. Although it is not possible to travel faster than the speed of light, the effective speed is faster than light. This warping of space and time is precisely mathematically specified by the [[Lorentz factor]], which depends on velocity. Although only theoretical when published over 100 years ago, the effect has since been [[Tests of special relativity|measured and confirmed]] many times. In the limit, at light speed time stops completely (relative to a certain reference frame) and it is possible to travel infinite distances across space with no passage of time.<ref>{{Cite journal |last=Einstein |first=Albert |year=1905 |title=Zur Elektrodynamik bewegter Körper |url=http://sedici.unlp.edu.ar/handle/10915/2786 |journal=Annalen der Physik |volume=322 |issue=10 |pages=891–921 |bibcode=1905AnP...322..891E |doi=10.1002/andp.19053221004 |doi-access=free}}</ref><ref>{{Citation |last=Minkowski |first=Hermann |title=Die Grundgleichungen für die elektromagnetischen Vorgänge in bewegten Körpern |work=Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse |pages=53–111 |year=1908 |orig-year=1907 |trans-title=[[s:Translation:The Fundamental Equations for Electromagnetic Processes in Moving Bodies|The Fundamental Equations for Electromagnetic Processes in Moving Bodies]] |title-link=s:Die Grundgleichungen für die elektromagnetischen Vorgänge in bewegten Körpern}}</ref><ref>{{Cite news |last=Overbye |first=Dennis |date=2005-06-28 |title=A Trip Forward in Time. Your Travel Agent: Einstein. |work=[[The New York Times]] |url=https://www.nytimes.com/2005/06/28/science/a-trip-forward-in-time-your-travel-agent-einstein.html?_r=0 |access-date=2015-12-08}}</ref><ref>{{Cite book |last=Gott |first=Richard J. |title=Time Travel in Einstein's Universe |year=2002 |pages=75}}</ref> 

The solution to Einstein’s field equations proposed by Alcubierre defines a spacetime metric—known as the '''Alcubierre metric'''—where spacetime itself is distorted in a controlled manner. The metric creates a region of compressed spacetime in front of the spacecraft and expanded spacetime behind it, forming a "warp bubble." The spacecraft resides within this bubble, moving with the local spacetime without experiencing relativistic time dilation or violating causality.

Mathematically, the Alcubierre metric is expressed as:

<math>dx^2 = -c^2 dt^2 + \left(dx - v_s f(r_s) dt\right)^2 + dy^2 + dz^2</math>

where:

* <math>v_s</math> is the speed of the warp bubble,
* <math>f(r_s)</math> is a shape function that determines the smoothness and size of the bubble,
* <math>r_s = \sqrt{(x - x_s(t))^2 + y^2 + z^2}</math>is the radial distance from the spacecraft center.

The creation of such a bubble requires '''[[exotic matter]]'''—substances with negative energy density (a violation of the Weak Energy Condition). [[Casimir effect]] experiments have hinted at the existence of negative energy in quantum fields, but practical production at the required scale remains speculative.

Similarly, a quantum drive might utilize quantum field theory to exploit vacuum energy, leveraging phenomena such as the '''[[zero-point energy]]''' of the [[Quantum vacuum state|quantum vacuum]]. The drive could theoretically manipulate virtual particle pairs or create localized energy gradients via quantum entanglement. The energy density of the quantum vacuum, often estimated as 10113J/m3 in the context of quantum field fluctuations, could provide immense power if harnessed effectively.

Although the concept of warp drive has originated in fiction, it has received some scientific consideration, most notably related to the 1990s concept of the [[Alcubierre drive]].<ref name=":1" /> Alcubierre stated in an email to [[William Shatner]] that his theory was directly inspired by the term used in the TV series ''[[Star Trek]]''<ref>{{cite web|last=Shapiro|first=Alan|title=The Physics of Warp Drive|url=http://www.alan-shapiro.com/the-physics-of-warp-drive/|archive-url=https://web.archive.org/web/20130424012220/http://www.alan-shapiro.com/the-physics-of-warp-drive/|archive-date=24 April 2013|access-date=2 June 2013}}</ref> and cites the "'warp drive' of science fiction" in his 1994 article.<ref name="Alcubierre94"/>

In 2021, [[DARPA]]-funded researcher [[Harold G. White|Harold White]], of the Limitless Space Institute, claimed that he had succeeded in creating a real warp bubble, saying "our detailed numerical analysis of our custom [[Casimir effect|Casimir cavities]] helped us identify a real and manufacturable nano/microstructure that is predicted to generate a negative vacuum energy density such that it would manifest a real nanoscale warp bubble, not an analog, but the real thing."<ref>{{Cite web |last=Coontz |first=Lauren |date=December 9, 2021 |title=DARPA and NASA Scientists Accidentally Create Warp Bubble for Interstellar Travel |url=https://coffeeordie.com/alcubierre-white-warp-drive |access-date=2024-05-27 |website=Coffee or Die Magazine |language=en}}</ref>