《那些古怪又讓人憂心的問題》第137期:中子子彈(1)
NEUTRON BULLET
Q. If a bullet with the density of a neutron star were fired from a handgun (ignoring the how) at the Earth's surface, would the Earth be destroyed?
Q．如果一顆密度與中子星相當的子彈在地球表面從手槍中發射出來（忽略怎麼發射這個問題），那麼地球會被摧毀嗎？#NAME?
——夏洛特•安斯沃思
A. A BULLET WITH THE density of a neutron star would weigh about as much as the Empire State Building.
A．密度與中子星相當的子彈，重量差不多相當於帝國大廈的重量。Whether we fired it from a gun or not, the bullet would fall straight through the ground, punching through the crust as if the rock were wet tissue paper.
不管你是否是從手槍中射出，這個子彈都會直直地落向地面，擊穿地殼，視岩石如溼紙巾。We'll look at two different questions:
我們會關注這兩個的問題：What would the bullet's passage do to the Earth?
• 子彈落下產生的一長條小洞會對地球有什麼影響？If we kept the bullet here on the surface, what would it do to its surroundings? Could we touch it?
• 如果我們把子彈放在地表，會對周圍環境產生什麼影響？我們能用手觸碰它嗎？First, a little bit of background:
首先，來看一點背景介紹：What are neutron stars?
什麼是中子星？A neutron star is what's left over after a giant star collapses under its own s exist in a balance. Their massive gravity is always trying to make them collapse inward, but that squeezing sets off several different forces that push them back apart.
中子星是一顆巨大恆星因自身重力坍縮後形成的產物。恆星的存在是一個平衡過程，巨大的引力傾向於使整顆恆星向內坍縮，不過收縮會激發好幾種不同的向外推的力。In the Sun, the thing holding off collapse is heat from nuclear fusion. When a star runs out of fusion fuel, it contracts (in a complicated process involving several explosions) until the collapse is stopped by the quantum laws that keep matter from overlapping with other matter.1
在太陽中心，抵抗坍縮的力來自於核聚變產生的熱量。當一顆恆星耗盡核聚變燃料時，它會收縮（這個過程相當複雜，其中還會夾雜好幾次爆炸），直到由於受到量子定律的限制，兩個物質不能相互重疊而停了下來。1If the star is heavy enough, it overcomes that quantum pressure and collapses further (with another, more massive explosion) to become a neutron star. If the remnant is even heavier, it becomes a black hole.
如果一顆恆星足夠重，它就能克服量子壓力進一步坍縮（還會引發又一次更劇烈的爆炸）形成中子星。如果質量再大一些，它就會形成黑洞。
