The mysterious substance known as dark matter may actually be an illusion created by gravitational interactions between short-lived particles of matter and antimatter, a new study says.
一项新的研究表明：被称作暗物质的神秘物质可能只是一种虚像，由物质与反物质的短寿命粒子之间的引力相互作用而产生的。
子弹星团（上）被认为是暗物质存在的最有力证据之一
Dark matter is thought to be an invisible substance that makes up almost a quarter of the mass in the universe. The concept was first proposed in 1933 to explain why the outer galaxies in galaxy clusters orbit faster than they should, based on the galaxies' visible mass.
人们认为暗物质是由将近占
宇宙四分之一质量的不可见物质组成的。并在1933年首次提出解释
星系外环在星团轨道上的转速比基于星系可见物质而得出的理论转速要高的概念。
(Related: "Dark-Matter Galaxy Detected: Hidden Dwarf Lurks Nearby?")
（相关资料：《
检测到暗物质星系：周围有潜伏的矮星吗？》）
At the observed speeds, the outer galaxies should be flung out into space, since the clusters don't appear to have enough mass to keep the galaxies at their edges gravitationally bound.
星系外环应以可以观测到的速度被甩入太空，因为星团的质量不足以通过万有引力来束缚星系的边缘部分。
So physicists proposed that the galaxies are surrounded by halos of invisible matter. This dark matter provides the extra mass, which in turn creates gravitational fields strong enough to hold the clusters together.
所以物理学家提出星系被不可见物质的晕圈所包围。这些暗物质轮流产生重力场以提供足够的附加质量将星团聚集在一起。
In the new study, physicist Dragan Hajdukovic at the European Organization for Nuclear Research (CERN) in Switzerland proposes an alternative explanation, based on something he calls the "gravitational polarization of the quantum vacuum."
在一项新的研究中，瑞士
欧洲核子研究委员会物理学家Dragan Hajdukovic提出了另一种基于量子真空的引力极化理论的解释。
(Also see "Einstein's Gravity Confirmed on a Cosmic Scale.")
（同见《
爱因斯坦引力在宇宙大尺度上得以证实》）
1
Empty Space Filled With "Virtual" Particles
充满“虚”粒子的真空
The quantum vacuum is the name physicists give to what we see as empty space.
量子真空是物理学家为我们所理解的真空起的名字。
According to quantum physics, empty space is not actually barren but is a boiling sea of so-called virtual particles and antiparticles constantly popping in and out of existence.
量子物理学认为，真空并不是真正是空的，而是沸腾的海洋——被称作虚粒子与反粒子的东西不停出现与消失。
Antimatter particles are mirror opposites of normal matter particles. For example, an antiproton is a negatively charged version of the positively charged proton, one of the basic constituents of the atom.
反物质粒子与正常物质粒子镜像对立， 正象组成原子基本成分之一——带正电的质子与带负电的反质子的关系。
(See "Antimatter Found Orbiting Earth—A First.")
（见《
首次发现反物质围绕地球-A运转》）
When matter and antimatter collide, they annihilate in a flash of energy. The virtual particles spontaneously created in the quantum vacuum appear and then disappear so quickly that they can't be directly observed.
当物质与反物质发生碰撞，他们在放出一瞬间的光能后随即消失。量子真空中自发产生的虚粒子以不被察觉的速度出现与消失。
In his new mathematical model, Hajdukovic investigates what would happen if virtual matter and virtual antimatter were not only electrical opposites but also gravitational opposites—an idea some physicists previously proposed.
Hajdukovic 用一个新的数学模型来研究如果虚物质与虚反物质不仅电极对立而且引力对立时会有什么情况出现——一些物理学家曾经提出的理论。
"Mainstream physics assumes that there is only one gravitational charge, while I have assumed that there are two gravitational charges," Hajdukovic said.
Hajdukovic 说：“主流物理学假设仅有一个引力荷存在，而我假设两个。”
According to his idea, outlined in the current issue of the journal Astrophysics and Space Science, matter has a positive gravitational charge and antimatter a negative one.
在近期的《
天体物理与空间科学》杂志上，他对物质带有一个正引力荷，而反物质带有一个负引力荷的假设进行了概述。
That would mean matter and antimatter are gravitationally repulsive, so that an object made of antimatter would "fall up" in the gravitational field of Earth, which is composed of normal matter.
那将意味着物质与反物质之间存在万有斥力，由反物质组成的物体将在由正常物质构成的地球的引力场中“跌倒、起来”。
Particles and antiparticles could still collide, however, since gravitational repulsion is much weaker than electrical attraction.
粒子与反粒子仍然存在碰撞的机会，因为万有斥力要比电极引力弱得多。
(Related: "At Ten, Dark Energy 'Most Profound Problem' in Physics.")
（相关资料：《
暗能量——十年来物理学中最深奥的问题》）
How Galaxies Could Get Gravity Boost
星系如果获得引力助推力
While the idea of particle antigravity might seem exotic, Hajdukovic says his theory is based on well-established tenants in quantum physics.
粒子反引力理论可能有点不可思议，而Hajdukovic 解释说他的理论是以量子物理中已完善的理论为基础的。
For example, it's long been known that particles can team up to create a so-called electric dipole, with positively charge particles at one end and negatively charged particles at the other. (See "Universe's Existence May Be Explained by New Material.")
例如，一端带正电荷而另一端带负电荷的粒子聚积在一起产生所谓的电偶极子就是一种早已被认可的理论。（见《
一种新材料可能为宇宙的存在提供依据》）
According to theory, there are countless electric dipoles created by virtual particles in any given volume of the quantum vacuum.
这个理论告诉我们，在任何给定体积的量子真空中都存在数不清的由虚粒子产生的电偶极子。
All of these electric dipoles are randomly oriented—like countless compass needles pointing every which way. But if the dipoles form in the presence of an existing electric field, they immediately align along the same direction as the field.
所有这些电偶极子随机排列———象无数指向四面八方的罗盘针。但是，如果这些电偶极子处于电场中，他们就会立即沿电场的方向排列。
According to quantum field theory, this sudden snapping to order of electric dipoles, called polarization, generates a secondary electric field that combines with and strengthens the first field.
在量子场理论中，这个瞬间电偶极子有序化的过程被称为极化，它产生一个次电场，与第一个电场结合并使其强化。
Hajdukovic suggests that a similar phenomenon happens with gravity. If virtual matter and antimatter particles have different gravitational charges, then randomly oriented gravitational dipoles would be generated in space.
Hajdukovic 提出，引力现象与此相似。如果虚物质和反物质粒子带有不同引力荷，随机排列的引力偶极子就会在空间中产生。
If these gravitational dipoles form near a galaxy—a massive object that would have a strong gravitational field—the dipoles should become polarized.
如果这些引力偶极子接近一个星系——一个具有强引力场的巨大物体——引力偶极子应该被极化。
This polarization would generate a secondary gravitational field that would combine with and strengthen the galaxy's gravitational field.
极化将产生一个次引力场，融入并加强星系引力场。
"My theory makes the gravitational field of a galaxy stronger—without dark matter," Hajdukovic said.
“我的理论可以解释一个星系的引力场在没有暗物质存在的情况下变得更强，”Hajdukovic 说。
(Related: "New Proof Unknown 'Structures' Tug at Our Universe.")
（相关资料：《
未知结构拖曳宇宙的新证据》）
Evidence for Dark Matter "Very Compelling"
“令人关注的”有关暗物质的证据
Physicist David Evans called the new study a "very interesting theoretical exercise," but he said he isn't ready to abandon dark matter just yet.
物理学家David Evanst称这项研究是“非常有趣的理论实践”，但他说他还没准备摒弃暗物质理论。
"The evidence for dark matter is now very compelling," said Evans, of the University of Birmingham, who leads the U.K. team for the ALICE detector at CERN's Large Hadron Collider.
“有关暗物质的证据是非常令人关注的，”伯明翰大学埃文斯说。他负责用于欧洲粒子物理研究所的大型强子对撞机的爱丽莎探测器英国小组方面的工作。
For example, in 2006 astronomers unveiled a photo of two colliding galaxies known as the Bullet cluster that purportedly showed the separation of matter from dark matter.
例如，2006年宇航员们公布了
一张两颗被称作子弹星团的星系相碰撞的照片，据称它显示出物质独立于暗物质。
A similar effect was observed in the Pandora cluster earlier this summer, said Evans, who was not involved in the study.
今年初夏在潘多拉星团有一个类似的发现，爱文斯说，但他没有参加这项研究。
(Related: "Dark Matter Proof Found Over Antarctica?")
（相关资料：《
是否在南极洲上空发现暗物质存在的证据？》）
Hajdukovic said he is currently expanding his theory to account for these observations. His preliminary calculations, he said, suggest that "what is observed in the Bullet cluster and more recently at the Pandora cluster may be understood in the framework of the gravitational polarization of the quantum vacuum."
Hajdukovic说他正在扩展他的理论以便解这些现象。他称，他的初步计算可以解释，“在量子真空引力极化的框架下，在子弹星团及最近发现的潘多拉星团观察到的东西。”
CERN physicist Michael Doser agreed that Hajdukovic's ideas are "unorthodox" but did not immediately dismiss the new theory.
欧洲核子研究委员会物理学家迈克尔.德泽尔承认Hajdukovic的理论是非正统的，但他没有马上放弃这个新理论。
"The mainstream view suffers from the lack of a detected dark matter particle, and so exploring a wide range of possibilities is at this moment perfectly legitimate, as long as they are compatible with all data," Doser said in an email.
“主流观点苦于缺乏可检测到的暗物质粒子，所以目前对多种可能性的探索是合理的，只要它们与所有数据兼容，”都瑟在一封电子邮件中写道。
Doser is a member of CERN's AEgIS experiment, which aims to measure the gravitational charge of antihydrogen, the antimatter version of hydrogen, and thus would prove whether matter and antimatter are gravitationally repulsive.
都瑟是欧洲核子研究委员会AEgIS 实验的参与人员之一。这个实验旨在测量与氢相对的反氢的引力荷，从而可以证实物质和反物质之间是否存在万有斥力。
"In a few years," Doser said, "we should definitely be in a position to confirm or refute [Hajdukovic's] hypothesis."
“在今后几年内，”都瑟说，“我们一定能够找到一个基点去证实Hajdukovic的假设是否正确。”
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