In Catholic theology, Limbo (Latin "limbus", edge or boundary, referring to the "edge" of Hell) is a speculative idea about the afterlife condition of those who die in original sin without being assigned to the Hell of the Damned.
 Medieval theologians of western Europe described the underworld ("hell", "hades", "infernum") as divided into four distinct parts: Hell of the Damned, Purgatory, Limbo of the Fathers or Patriarchs, and Limbo of the Infants.
 However, Limbo of the Infants is not an official doctrine of the Catholic Church.
 Also, Purgatory is better classified as part of heaven, as official Church doctrine states that all souls in the state of purgation or cleansing (often referred to as "in Purgatory") are to be fully welcomed into eternal life after becoming fully purified.
Harold G. "Sonny" White is a mechanical engineer, aerospace engineer and applied physicist who is the Advanced Propulsion Team Lead for the NASA Engineering Directorate and is known for proposing new Alcubierre drive concepts and promoting advanced propulsion projects, under development at the NASA Johnson Space Center, including the first practical experiment to test the existence of Alcubierre drive effects.
IXS "Enterprise", named after Starship "Enterprise" from the "Star Trek" fictional franchise, is a conceptual interstellar superluminal spacecraft designed by NASA scientist Dr. Harold G. White, revealed at SpaceVision 2013, designed for the goal of achieving warp travel.
 The conceptual spacecraft would be a modified version of the Alcubierre drive.
 Dr. White is currently running the White–Juday warp-field interferometer experiment in order to develop a proof of concept for Alcubierre-style warp travel, if possible.
 The Alcubierre drive uses exotic matter (not to be confused with antimatter) to travel faster than light.
Miguel Alcubierre Moya (born March 28, 1964 in Mexico City) is a Mexican theoretical physicist.
In mathematical physics, de Sitter invariant special relativity is the speculative idea that the fundamental symmetry group of spacetime is the indefinite orthogonal group SO(4,1), that of de Sitter space.
 In the standard theory of general relativity, de Sitter space is a highly symmetrical special vacuum solution, which requires a cosmological constant or the stress–energy of a constant scalar field to sustain.
The Walking City was an idea proposed by British architect Ron Herron in 1964.
 In an article in avant-garde architecture journal Archigram, Ron Herron proposed building massive mobile robotic structures, with their own intelligence, that could freely roam the world, moving to wherever their resources or manufacturing abilities were needed.
 Various walking cities could interconnect with each other to form larger 'walking metropolises' when needed, and then disperse when their concentrated power was no longer necessary.
 Individual buildings or structures could also be mobile, moving wherever their owner wanted or needs dictated.
The Big Society was a political ideology developed in the early 21st century.
 The idea proposed "integrating the free market with a theory of social solidarity based on hierarchy and voluntarism".
 Conceptually it "draws on a mix of conservative communitarianism and libertarian paternalism".
 Its roots "can be traced back to the 1990s, and to early attempts to develop a non-Thatcherite, or post-Thatcherite, brand of UK conservatism" such as David Willetts' Civic Conservatism and the revival of Red Toryism.
 Some commentators have seen the Big Society as invoking Edmund Burke's idea of civil society, putting it into the sphere of one-nation conservatism.
God-Building, an idea proposed by some prominent early Marxists of the Bolshevik faction of the Russian Social Democratic Labour Party, proved very controversial.
 Inspired by Ludwig Feuerbach's "religion of humanity", it had some precedent in the French Revolution with the "cult of reason".
 The idea proposed that in place of the abolition of religion, there should be a meta-religious context in which religions were viewed primarily in terms of the psychological and social effect of ritual, myth, and symbolism, and which attempted to harness this force for pro-communist aims, both by creating new ritual and symbolism, and by re-interpreting existing ritual and symbolism in a socialist context.
 In contrast to the atheism of Lenin, the God-Builders took an official position of agnosticism.
The Nucifer Experiment is a proposed test of equipment and methodologies for using neutrino detection (or, more specifically, antineutrino detection) for the monitoring of nuclear reactor activity and the assessment of the isotopic composition of reactor fuels for non-proliferation treaty compliance monitoring.
 Based upon an idea proposed by L.A. Mikaélyan in 1977, the Nucifer Experiment was proposed to the IAEA in October 2008.
The Alcubierre drive or Alcubierre warp drive (or Alcubierre metric, referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by Mexican theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created.

Question: The Alcubierre drive is a speculative idea proposed by a Mexican theoretical physicist that was born in 1964 in what city?
Answer: Mexico City