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弱人择原理的形式国家生活可以存在只在短暂的时间内我们的宇宙的历史。强形式原则的国家从所有可能的值为自然和宇宙的初始条件的基本常数，只有一小部分可能允许向窗体的生活在所有在任何时间。（请参阅边界条件; 基本常数的性质......
Industry:Astronomy
1） 相反的银河系中心天空的方向。2） 在位于银河系中心的对面的银河平面中点。在这里我们凝视向银盘的边缘。最近 anticenter 的明亮恒星是 El Nath 金牛星座中。
Industry:Astronomy
反中子的粒子。一个中子和 antineutron 都有相同的质量和零电荷，但可以由他们的互动区分： 一个中子和 antineutron 可以消灭到 γ 射线，而两个中子则不能。
Industry:Astronomy
1) An elementary particle of opposite charge but otherwise identical to its partner. Most of the observable universe consists of particles and matter, as opposed to antiparticles and antimatter.
2) Atomic particles that have the same mass as, but opposite charge and orbital direction to, an ordinary particle. Thus, instead of negatively charged electrons, atoms of antimatter have positrons. A quantity of antimatter coming into contact with matter would "cancel out" - annihilate, with total conversion of mass to energy - an exact proportion of matter corresponding to the original quantity of antimatter, provided that the elements in the matter also corresponded with the "elements" in the antimatter, i.e., that the atoms were equivalent but opposite.
3) For every known type of particle, there exists an antiparticle with exactly the same mass, but with the opposite electric charge. When a particle and its antiparticle come together, they can always annihilate to form gamma rays. The antiparticle of an electrically neutral particle is sometimes the same as the original particle (e.g., photons) and sometimes it is distinct (e.g., neutrons.)
4) Particles predicted by combining the theories of special relativity and quantum mechanics. For each particle, there must exist an antiparticle with the opposite charge, magnetic moment and other internal quantum numbers (e.g., lepton number, baryon number, strangeness, charm, etc.), but with the same mass, spin and lifetime. Note that certain neutral particles (such as the photon and π0) are their own antiparticles.
5) Particles with identical mass and spin as those of ordinary matter, but with opposite charge. Antimatter has been produced experimentally, but little of it is found in nature. Why this should be so is one of the questions that must be answered by any adequate theory of the early universe.
Industry:Astronomy
