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blackhole 2008-3-3 22:18
不知道庞加莱离相对论到底差多远？
以下摘自李醒民的《庞加莱》。
[url]http://hps.phil.pku.edu.cn/viewarticle.php?sid=1836&st=0[/url]
看了之后我很吃惊：他不几乎已经得到相对论了吗？他到底差了什么东西，使得他只能是“先驱”？
我知道的一点是，他没有放弃以太假设。但以太假设跟他的这些结论能够协调吗？是怎么协调的？
3．相对论的先驱
早在1900年之前，庞加莱就掌握了建立狭义相对论的一切必要材料，并在1904~1905年间找到了它的数学表示。作为相对论的先驱，他比马赫和H．A．洛伦兹(Lorentz)更前进了一步。
在1895年，庞加莱就对当时以太漂移实验的解释表示不满，他批评洛伦兹过多地引入特设假设。他相信，用任何实验手段——力学的、光学的、电学的——都不可能检测到地球的绝对运动。他已经意识到，采取这种立场相当于在理论上提出一个普遍的物理定律：“不可能测出有重物质的绝对运动，或者更明确地说，不可能测出有重物质相对于以太的运动。人们所能提供的一切就是有重物质相对于有重物质的运动。”1900年，他把这个定律称 为“相对运动原理”：“任何系统的运动必须服从同样的定律，不管它是相对于固定轴而言还是相对于作匀速直线运动的可动轴而言。”在1902年的《科学与假设》中，首次出现了“相对性原理”的提法。不过，相对性原理的正式提出和标准表述是庞加莱1904年9月在圣路易斯讲演中做出的。他把它作为物理学六大基本原理之一提了出来：“相对性原理，根据这个原理，物理现象的定律应该是相同的，不管观察者处于静止还是处于匀速直线运动。于是，我们没有、也不可能有任何手段来辨别我们是否做这样一种运动。”也就是在这次讲演中，他惊人地预见了新力学的大致图景：惯性随速度而增加，光速会变为不可逾越的极限。原来的比较简单的力学依然保持为一级近似，因为它对不太大的速度还是正确的，以致在新力学中还能够发现旧力学。
在1898年的“时间的测量”(La mésure de temps)一文中，庞加莱不仅批判了绝对时间、绝对空间和绝对同时性的概念，而且还提出了建设性的建议：承认光速不变是一个公设，并用爱因斯坦后来使用的术语讨论了远距离的同时性的确定问题。他说：“(光具有变的速度，尤其是它的速度在一切方向上都是相同的，)这是一个公设，没有这个公设，就无法测量光速。”庞加莱利用两个观察者(爱因斯坦的讨论只用一个观察者)、光讯号和时钟，讨论了时钟同步和同时性的定义问题，得出了与爱因斯坦1905年的结论相同的结果。
1904年后期到1905年中期，庞加莱给洛伦兹写了三封信，这三封信的基本思想在“论电于动力学”(Sur 1a dynamique de iélectron)一文中得到发展。这篇论文的缩写本于1905年6月5日不发表，全文则发表于1906年。他在文中第一个提出了精确的洛伦兹变换，指出该变换的群的性质。“洛伦兹变换”、“洛伦兹群”、‘洛伦兹不变量”等术语，都是他首先使用的。他还得到了正确的电荷和电流密度的变换(洛伦兹得出的变换式是错的)，证明了速度变换，考虑了体积元的变换，得到了电荷密度和电流的变换。这样一来，麦克斯韦-洛伦兹方程首次在洛伦兹变换下严格地变成不变量。庞加莱还导出了电磁标量势和矢量势、单位体积的力、单位电荷的力的变换，这些公式甚至在60年代前后的文献中也难以找到。尤其是，庞加莱为了利用在具有确定的正度规x2+y2+z2+τ2的四维空间中的不变量理论，还引入了四维矢量，使用了虚时间坐标(τ＝ict)。他还揭示出洛伦兹变换恰恰是四维空间绕原点的转动。庞加莱的这一工作，对H．闵可夫斯基(Minkowski)后来的四维时空表示法有直接影响。庞加莱也是第一个在他的电子动力学中研究牛顿引力定律的人，他甚至使用了“引力波”这个词。shanqin 2008-3-3 23:21
粉丝对偶像的科学成就的描述都带有很大主观性，当他的偶像对某个理论作出基础贡献时，就突出这个基础多么重要，当他的偶像发展了别人的理论时，就强调这个发展是多么有飞跃性。
李醒民教授是Poincare的粉丝季候风 2008-3-4 03:37
这个其实很好验证，查查 Poincare 全集就知道了。可惜我没读过。其实也无所谓，Poincare 的确看到了很多，但他本人既然没有来争这里的荣誉，要么因为承认 Einstein 看到的比他更多，要么就是不在乎这个荣誉。也许对他来说，新的引力理论才是真正的荣誉，可惜 Einstein 在这个问题上明显比同时代的人高明一个档次。blackhole 2010-1-18 22:10
刘辽的《狭义相对论》（第二版）中对庞加莱的介绍：
1、认为迈克尔孙-莫雷实验及相关实验的零结果证明了“绝对运动不可能”。观测者不可能知道自己是静止还是运动的。一切寻找绝对参考系的努力都不会成功。
2、认识到洛伦兹变换的深刻含义，认识到参考系在数学描述上的等价性意味着相对性原理的正确性。提出庞加莱变换群。
3、认为应该建立一个全新的力学，在其中惯性将随着速度而增大，而光速是一个极限。
但是，庞加莱坚持认为存在绝对静止的以太，并始终没有承认相对论。PENG_Bo 2010-1-19 00:54
广义相对论在以前也有位著名人士差不多看到。。。忘了是哪位dfj 2010-1-19 01:26
Wiki 讲得比较多
[url]http://en.wikipedia.org/wiki/Henri_Poincar%C3%A9#Work_on_relativity[/url]
按照wiki，庞加莱是因为参加一项确定国际时区的工作而考虑时钟同步问题的。
In The Measure of Time (1898), Poincaré said, " A little reflection is sufficient to understand that all these affirmations have by themselves no meaning. They can have one only as the result of a convention." He also argued, that scientists have to set the constancy of the speed of light as a postulate to give physical theories the simplest form.[9] Based on these assumptions he discussed in 1900 Lorentz's "wonderful invention" of local time and remarked that it arose when moving clocks are synchronised by exchanging light signals assumed to travel with the same speed in both directions in a moving frame.[10]
He discussed the "principle of relative motion" in two papers in 1900[10][11] and named it the principle of relativity in 1904, according to which no physical experiment can discriminate between a state of uniform motion and a state of rest.[12] In 1905 Poincaré wrote to Lorentz about Lorentz's paper of 1904, which Poincaré described as a "paper of supreme importance." In this letter he pointed out an error Lorentz had made when he had applied his transformation to one of Maxwell's equations, that for charge-occupied space, and also questioned the time dilation factor given by Lorentz.[13] In a second letter to Lorentz, Poincaré gave his own reason why Lorentz's time dilation factor was indeed correct after all: it was necessary to make the Lorentz transformation form a group and gave what is now known as the relativistic velocity-addition law.[14] Poincaré later delivered a paper at the meeting of the Academy of Sciences in Paris on 5 June 1905 in which these issues were addressed. In the published version of that he wrote[15]:
The essential point, established by Lorentz, is that the equations of the electromagnetic field are not altered by a certain transformation (which I will call by the name of Lorentz) of the form:
...
Mass-energy relation
Like others before, Poincaré (1900) discovered a relation between mass and electromagnetic energy. While studying the conflict between the action/reaction principle and Lorentz ether theory, he tried to determine whether the center of gravity still moves with a uniform velocity when electromagnetic fields are included. He noticed that the action/reaction principle does not hold for matter alone, but that the electromagnetic field has its own momentum. Poincaré concluded that the electromagnetic field energy of an electromagnetic wave behaves like a fictitious fluid ("fluide fictif") with a mass density of E/c2. If the center of mass frame is defined by both the mass of matter and the mass of the fictitious fluid, and if the fictitious fluid is indestructible — it's neither created or destroyed — then the motion of the center of mass frame remains uniform. But electromagnetic energy can be converted into other forms of energy. So Poincaré assumed that there exists a non-electric energy fluid at each point of space, into which electromagnetic energy can be transformed and which also carries a mass proportional to the energy. In this way, the motion of the center of mass remains uniform. Poincaré said that one should not be too surprised by these assumptions, since they are only mathematical fictions.
However, Poincaré's resolution led to a paradox when changing frames: if a Hertzian oscillator radiates in a certain direction, it will suffer a recoil from the inertia of the fictitious fluid. Poincaré performed a Lorentz boost (to order v/c) to the frame of the moving source. He noted that energy conservation holds in both frames, but that the law of conservation of momentum is violated. This would allow perpetual motion, a notion which he abhorred. The laws of nature would have to be different in the frames of reference, and the relativity principle would not hold. Therefore he argued that also in this case there has to be another compensating mechanism in the ether.
Poincaré himself came back to this topic in his St. Louis lecture (1904).[12] This time (and later also in 1908) he rejected[18] the possibility that energy carries mass and also the possibility, that motions in the ether can compensate the above mentioned problems:
“ The apparatus will recoil as if it were a cannon and the projected energy a ball, and that contradicts the principle of Newton, since our present projectile has no mass; it is not matter, it is energy. [..] Shall we say that the space which separates the oscillator from the receiver and which the disturbance must traverse in passing from one to the other, is not empty, but is filled not only with ether, but with air, or even in inter-planetary space with some subtile, yet ponderable fluid; that this matter receives the shock, as does the receiver, at the moment the energy reaches it, and recoils, when the disturbance leaves it? That would save Newton's principle, but it is not true. If the energy during its propagation remained always attached to some material substratum, this matter would carry the light along with it and Fizeau has shown, at least for the air, that there is nothing of the kind. Michelson and Morley have since confirmed this. We might also suppose that the motions of matter proper were exactly compensated by those of the ether; but that would lead us to the same considerations as those made a moment ago. The principle, if thus interpreted, could explain anything, since whatever the visible motions we could imagine hypothetical motions to compensate them. But if it can explain anything, it will allow us to foretell nothing; it will not allow us to choose between the various possible hypotheses, since it explains everything in advance. It therefore becomes useless. ”
He also discussed two other unexplained effects: (1) non-conservation of mass implied by Lorentz's variable mass γm, Abraham's theory of variable mass and Kaufmann's experiments on the mass of fast moving electrons and (2) the non-conservation of energy in the radium experiments of Madame Curie.
It was Albert Einstein's concept of mass–energy equivalence (1905) that a body losing energy as radiation or heat was losing mass of amount m = E/c2 that resolved[19] Poincare's paradox, without using any compensating mechanism within the ether.[20] The Hertzian oscillator loses mass in the emission process, and momentum is conserved in any frame. However, concerning Poincaré's solution of the Center of Gravity problem, Einstein noted that Poincaré's formulation and his own from 1906 were mathematically equivalent.[21]
Poincaré and Einstein
Einstein's first paper on relativity was published three months after Poincaré's short paper,[15] but before Poincaré's longer version.[16] It relied on the principle of relativity to derive the Lorentz transformations and used a similar clock synchronisation procedure (Einstein synchronisation) that Poincaré (1900) had described, but was remarkable in that it contained no references at all. Poincaré never acknowledged Einstein's work on Special Relativity. Einstein acknowledged Poincaré in the text of a lecture in 1921 called Geometrie und Erfahrung in connection with non-Euclidean geometry, but not in connection with special relativity. A few years before his death Einstein commented on Poincaré as being one of the pioneers of relativity, saying "Lorentz had already recognised that the transformation named after him is essential for the analysis of Maxwell's equations, and Poincaré deepened this insight still further ...."[22]
[[i] 本帖最后由 dfj 于 2010-1-19 01:39 编辑 [/i]]星空浩淼 2010-1-19 10:01
庞加莱坚持认为存在绝对静止的以太，并始终没有承认相对论。
---------------------------------------
庞加莱不承认相对论，的确是一种错误，庞加莱群不是涵盖了Lorentz群吗？
但是，说实话，也许未来的人们发现：的确可以认为存在绝对静止的以太！
例如，我们把整个宇宙中的真空背景定义为以太，由于我们无法观测到真空背景的“宏观定向速度”（即它是一个不可观测量），就定义真空背景的运动速度为零，即认为存在绝对静止的以太！只是这种“绝对静止”，是指相对于任何惯性参照系都是绝对静止的。
进一步地，也许宇宙中只存在两个本征速度：宇宙真空背景的零速度和静止质量为零物质的光速，它们相对于任何惯性参照系都是不变的。而其他亚光速，都是表观速度。
[[i] 本帖最后由 星空浩淼 于 2010-1-19 19:27 编辑 [/i]]页: [1]
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查看完整版本: 不知道庞加莱离相对论到底差多远？
blackhole 2008-3-3 22:18
不知道庞加莱离相对论到底差多远？
以下摘自李醒民的《庞加莱》。
[url]http://hps.phil.pku.edu.cn/viewarticle.php?sid=1836&st=0[/url]
看了之后我很吃惊：他不几乎已经得到相对论了吗？他到底差了什么东西，使得他只能是“先驱”？
我知道的一点是，他没有放弃以太假设。但以太假设跟他的这些结论能够协调吗？是怎么协调的？
3．相对论的先驱
早在1900年之前，庞加莱就掌握了建立狭义相对论的一切必要材料，并在1904~1905年间找到了它的数学表示。作为相对论的先驱，他比马赫和H．A．洛伦兹(Lorentz)更前进了一步。
在1895年，庞加莱就对当时以太漂移实验的解释表示不满，他批评洛伦兹过多地引入特设假设。他相信，用任何实验手段——力学的、光学的、电学的——都不可能检测到地球的绝对运动。他已经意识到，采取这种立场相当于在理论上提出一个普遍的物理定律：“不可能测出有重物质的绝对运动，或者更明确地说，不可能测出有重物质相对于以太的运动。人们所能提供的一切就是有重物质相对于有重物质的运动。”1900年，他把这个定律称 为“相对运动原理”：“任何系统的运动必须服从同样的定律，不管它是相对于固定轴而言还是相对于作匀速直线运动的可动轴而言。”在1902年的《科学与假设》中，首次出现了“相对性原理”的提法。不过，相对性原理的正式提出和标准表述是庞加莱1904年9月在圣路易斯讲演中做出的。他把它作为物理学六大基本原理之一提了出来：“相对性原理，根据这个原理，物理现象的定律应该是相同的，不管观察者处于静止还是处于匀速直线运动。于是，我们没有、也不可能有任何手段来辨别我们是否做这样一种运动。”也就是在这次讲演中，他惊人地预见了新力学的大致图景：惯性随速度而增加，光速会变为不可逾越的极限。原来的比较简单的力学依然保持为一级近似，因为它对不太大的速度还是正确的，以致在新力学中还能够发现旧力学。
在1898年的“时间的测量”(La mésure de temps)一文中，庞加莱不仅批判了绝对时间、绝对空间和绝对同时性的概念，而且还提出了建设性的建议：承认光速不变是一个公设，并用爱因斯坦后来使用的术语讨论了远距离的同时性的确定问题。他说：“(光具有变的速度，尤其是它的速度在一切方向上都是相同的，)这是一个公设，没有这个公设，就无法测量光速。”庞加莱利用两个观察者(爱因斯坦的讨论只用一个观察者)、光讯号和时钟，讨论了时钟同步和同时性的定义问题，得出了与爱因斯坦1905年的结论相同的结果。
1904年后期到1905年中期，庞加莱给洛伦兹写了三封信，这三封信的基本思想在“论电于动力学”(Sur 1a dynamique de iélectron)一文中得到发展。这篇论文的缩写本于1905年6月5日不发表，全文则发表于1906年。他在文中第一个提出了精确的洛伦兹变换，指出该变换的群的性质。“洛伦兹变换”、“洛伦兹群”、‘洛伦兹不变量”等术语，都是他首先使用的。他还得到了正确的电荷和电流密度的变换(洛伦兹得出的变换式是错的)，证明了速度变换，考虑了体积元的变换，得到了电荷密度和电流的变换。这样一来，麦克斯韦-洛伦兹方程首次在洛伦兹变换下严格地变成不变量。庞加莱还导出了电磁标量势和矢量势、单位体积的力、单位电荷的力的变换，这些公式甚至在60年代前后的文献中也难以找到。尤其是，庞加莱为了利用在具有确定的正度规x2+y2+z2+τ2的四维空间中的不变量理论，还引入了四维矢量，使用了虚时间坐标(τ＝ict)。他还揭示出洛伦兹变换恰恰是四维空间绕原点的转动。庞加莱的这一工作，对H．闵可夫斯基(Minkowski)后来的四维时空表示法有直接影响。庞加莱也是第一个在他的电子动力学中研究牛顿引力定律的人，他甚至使用了“引力波”这个词。shanqin 2008-3-3 23:21
粉丝对偶像的科学成就的描述都带有很大主观性，当他的偶像对某个理论作出基础贡献时，就突出这个基础多么重要，当他的偶像发展了别人的理论时，就强调这个发展是多么有飞跃性。
李醒民教授是Poincare的粉丝季候风 2008-3-4 03:37
这个其实很好验证，查查 Poincare 全集就知道了。可惜我没读过。其实也无所谓，Poincare 的确看到了很多，但他本人既然没有来争这里的荣誉，要么因为承认 Einstein 看到的比他更多，要么就是不在乎这个荣誉。也许对他来说，新的引力理论才是真正的荣誉，可惜 Einstein 在这个问题上明显比同时代的人高明一个档次。blackhole 2010-1-18 22:10
刘辽的《狭义相对论》（第二版）中对庞加莱的介绍：
1、认为迈克尔孙-莫雷实验及相关实验的零结果证明了“绝对运动不可能”。观测者不可能知道自己是静止还是运动的。一切寻找绝对参考系的努力都不会成功。
2、认识到洛伦兹变换的深刻含义，认识到参考系在数学描述上的等价性意味着相对性原理的正确性。提出庞加莱变换群。
3、认为应该建立一个全新的力学，在其中惯性将随着速度而增大，而光速是一个极限。
但是，庞加莱坚持认为存在绝对静止的以太，并始终没有承认相对论。PENG_Bo 2010-1-19 00:54
广义相对论在以前也有位著名人士差不多看到。。。忘了是哪位dfj 2010-1-19 01:26
Wiki 讲得比较多
[url]http://en.wikipedia.org/wiki/Henri_Poincar%C3%A9#Work_on_relativity[/url]
按照wiki，庞加莱是因为参加一项确定国际时区的工作而考虑时钟同步问题的。
In The Measure of Time (1898), Poincaré said, " A little reflection is sufficient to understand that all these affirmations have by themselves no meaning. They can have one only as the result of a convention." He also argued, that scientists have to set the constancy of the speed of light as a postulate to give physical theories the simplest form.[9] Based on these assumptions he discussed in 1900 Lorentz's "wonderful invention" of local time and remarked that it arose when moving clocks are synchronised by exchanging light signals assumed to travel with the same speed in both directions in a moving frame.[10]
He discussed the "principle of relative motion" in two papers in 1900[10][11] and named it the principle of relativity in 1904, according to which no physical experiment can discriminate between a state of uniform motion and a state of rest.[12] In 1905 Poincaré wrote to Lorentz about Lorentz's paper of 1904, which Poincaré described as a "paper of supreme importance." In this letter he pointed out an error Lorentz had made when he had applied his transformation to one of Maxwell's equations, that for charge-occupied space, and also questioned the time dilation factor given by Lorentz.[13] In a second letter to Lorentz, Poincaré gave his own reason why Lorentz's time dilation factor was indeed correct after all: it was necessary to make the Lorentz transformation form a group and gave what is now known as the relativistic velocity-addition law.[14] Poincaré later delivered a paper at the meeting of the Academy of Sciences in Paris on 5 June 1905 in which these issues were addressed. In the published version of that he wrote[15]:
The essential point, established by Lorentz, is that the equations of the electromagnetic field are not altered by a certain transformation (which I will call by the name of Lorentz) of the form:
...
Mass-energy relation
Like others before, Poincaré (1900) discovered a relation between mass and electromagnetic energy. While studying the conflict between the action/reaction principle and Lorentz ether theory, he tried to determine whether the center of gravity still moves with a uniform velocity when electromagnetic fields are included. He noticed that the action/reaction principle does not hold for matter alone, but that the electromagnetic field has its own momentum. Poincaré concluded that the electromagnetic field energy of an electromagnetic wave behaves like a fictitious fluid ("fluide fictif") with a mass density of E/c2. If the center of mass frame is defined by both the mass of matter and the mass of the fictitious fluid, and if the fictitious fluid is indestructible — it's neither created or destroyed — then the motion of the center of mass frame remains uniform. But electromagnetic energy can be converted into other forms of energy. So Poincaré assumed that there exists a non-electric energy fluid at each point of space, into which electromagnetic energy can be transformed and which also carries a mass proportional to the energy. In this way, the motion of the center of mass remains uniform. Poincaré said that one should not be too surprised by these assumptions, since they are only mathematical fictions.
However, Poincaré's resolution led to a paradox when changing frames: if a Hertzian oscillator radiates in a certain direction, it will suffer a recoil from the inertia of the fictitious fluid. Poincaré performed a Lorentz boost (to order v/c) to the frame of the moving source. He noted that energy conservation holds in both frames, but that the law of conservation of momentum is violated. This would allow perpetual motion, a notion which he abhorred. The laws of nature would have to be different in the frames of reference, and the relativity principle would not hold. Therefore he argued that also in this case there has to be another compensating mechanism in the ether.
Poincaré himself came back to this topic in his St. Louis lecture (1904).[12] This time (and later also in 1908) he rejected[18] the possibility that energy carries mass and also the possibility, that motions in the ether can compensate the above mentioned problems:
“ The apparatus will recoil as if it were a cannon and the projected energy a ball, and that contradicts the principle of Newton, since our present projectile has no mass; it is not matter, it is energy. [..] Shall we say that the space which separates the oscillator from the receiver and which the disturbance must traverse in passing from one to the other, is not empty, but is filled not only with ether, but with air, or even in inter-planetary space with some subtile, yet ponderable fluid; that this matter receives the shock, as does the receiver, at the moment the energy reaches it, and recoils, when the disturbance leaves it? That would save Newton's principle, but it is not true. If the energy during its propagation remained always attached to some material substratum, this matter would carry the light along with it and Fizeau has shown, at least for the air, that there is nothing of the kind. Michelson and Morley have since confirmed this. We might also suppose that the motions of matter proper were exactly compensated by those of the ether; but that would lead us to the same considerations as those made a moment ago. The principle, if thus interpreted, could explain anything, since whatever the visible motions we could imagine hypothetical motions to compensate them. But if it can explain anything, it will allow us to foretell nothing; it will not allow us to choose between the various possible hypotheses, since it explains everything in advance. It therefore becomes useless. ”
He also discussed two other unexplained effects: (1) non-conservation of mass implied by Lorentz's variable mass γm, Abraham's theory of variable mass and Kaufmann's experiments on the mass of fast moving electrons and (2) the non-conservation of energy in the radium experiments of Madame Curie.
It was Albert Einstein's concept of mass–energy equivalence (1905) that a body losing energy as radiation or heat was losing mass of amount m = E/c2 that resolved[19] Poincare's paradox, without using any compensating mechanism within the ether.[20] The Hertzian oscillator loses mass in the emission process, and momentum is conserved in any frame. However, concerning Poincaré's solution of the Center of Gravity problem, Einstein noted that Poincaré's formulation and his own from 1906 were mathematically equivalent.[21]
Poincaré and Einstein
Einstein's first paper on relativity was published three months after Poincaré's short paper,[15] but before Poincaré's longer version.[16] It relied on the principle of relativity to derive the Lorentz transformations and used a similar clock synchronisation procedure (Einstein synchronisation) that Poincaré (1900) had described, but was remarkable in that it contained no references at all. Poincaré never acknowledged Einstein's work on Special Relativity. Einstein acknowledged Poincaré in the text of a lecture in 1921 called Geometrie und Erfahrung in connection with non-Euclidean geometry, but not in connection with special relativity. A few years before his death Einstein commented on Poincaré as being one of the pioneers of relativity, saying "Lorentz had already recognised that the transformation named after him is essential for the analysis of Maxwell's equations, and Poincaré deepened this insight still further ...."[22]
[[i] 本帖最后由 dfj 于 2010-1-19 01:39 编辑 [/i]]星空浩淼 2010-1-19 10:01
庞加莱坚持认为存在绝对静止的以太，并始终没有承认相对论。
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庞加莱不承认相对论，的确是一种错误，庞加莱群不是涵盖了Lorentz群吗？
但是，说实话，也许未来的人们发现：的确可以认为存在绝对静止的以太！
例如，我们把整个宇宙中的真空背景定义为以太，由于我们无法观测到真空背景的“宏观定向速度”（即它是一个不可观测量），就定义真空背景的运动速度为零，即认为存在绝对静止的以太！只是这种“绝对静止”，是指相对于任何惯性参照系都是绝对静止的。
进一步地，也许宇宙中只存在两个本征速度：宇宙真空背景的零速度和静止质量为零物质的光速，它们相对于任何惯性参照系都是不变的。而其他亚光速，都是表观速度。
[[i] 本帖最后由 星空浩淼 于 2010-1-19 19:27 编辑 [/i]]页: [1]
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