Additional social stresses may also occur because of the population explosion or problems arising from mass migration movements—themselves made relatively easy nowadays by modern means of transport.

由于人口的猛增或大量人口流动（现代交通工具使这种流动相对容易）造成的种种问题也会对社会造成新的压力。

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Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect.

天文学家长期以来都在推测，最终可能会在星际空间或者是在难以探测的大量星系中发现丢失的重子质量。

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Petersburg, this location has widely been criticized by team officials, members of the media, and fans alike as inconveniently off-center from the critical population mass of the region.

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Today, no country is in the old sense far away when the consequences of regional instability and terrorism - and then also climate change, poverty, mass population movements and even organised crime - reverberate quickly round the globe.

BBC: In full: Brown security statement

Malthus famously argued that in a world in which economies grew arithmetically and population grew geometrically, mass want would be inevitable.

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