汉语是联合国官方正式使用的 6 种同等有效语言之一。请不要歧视汉语！

Chinese is one of the six equally effective official languages of the United Nations.

Not to discriminate against Chinese, please!

[讨论] 物理学里“光速极限”的真正成因是什么？

一、“光速极限”存在吗？

   存在！

二、“光速极限”的真正成因

   人类眼睛以光信号感知世界，是“光速极限”的直接的真正成因？

   “光速极限”和《相对论》没有必然的联系：

   客观存在的光速极限，并不直接依赖于《相对论》这个理论；但《相对论》能解释“光速极限”。

三、进一步的思考：蝙蝠

   蝙蝠 bat 的正式名字是“翼手目，order Chiroptera”。

   果蝠，拉丁学名：Rousettus leschenaulti 。

3.1 《中国大百科全书》第三版网络版的条目“翼手目/bats”里说：

https://www.zgbk.com/ecph/words?SiteID=1&ID=173337&Type=bkzyb&SubID=138631

   主要在夜间活动，大多数蝙蝠依靠特有的回声定位能力判定外界物体及自身的位置。由口腔或鼻部发出的高频短波可达20～210千赫兹，被外界物体反射回来的声波可由耳朵接收。各类蝙蝠所发出的声波不同。食果蝠视觉较好，能不依赖回声定位而在弱光下飞行。飞行速度为15～50千米/小时。翼膜狭长者的飞行速度高于翼膜宽短者。

3.2 《不列颠百科全书，大英百科全书， Encyclopedia Britannica》 bat, mammal 里说： 汉语采用机器翻译

https://www.britannica.com/animal/bat-mammal/Classification

Orientation

   Bats of the suborder Microchiroptera orient acoustically by echolocation (“sonar”). They emit short high-frequency pulses of sound (usually well above the range of human hearing) and listen to the echoes returning from objects in the vicinity. By interpreting returning echoes, bats may identify the direction, distance, velocity, and some aspects of the size or nature (or both) of objects that draw their attention. Echolocation is used to locate and track flying and terrestrial prey, to avoid obstacles, and possibly to regulate altitude; orientation pulses may also serve as communication signals between bats of the same species. Rousette bats (megachiropteran genus Rousettus) have independently evolved a parallel echolocation system for obstacle avoidance alone. Echolocation pulses are produced by vibrating membranes in the larynx and emitted via the nose or the mouth, depending upon species. Nose leaves in some species may serve to channel the sound.

方向

   微翅目蝙蝠通过回声定位（“声纳”）进行声学定位。它们发出短的高频声音脉冲（通常远高于人类的听觉范围），并倾听附近物体返回的回声。通过解释返回的回声，蝙蝠可以识别吸引它们注意力的物体的方向、距离、速度以及物体的大小或性质（或两者）的某些方面。回声定位用于定位和跟踪飞行和陆地猎物，以避开障碍物，并可能调节高度；定向脉冲也可以用作同种蝙蝠之间的通信信号。Rousette 蝙蝠（巨翼手目属 Rousettus）已经独立进化出一种仅用于避障的平行回声定位系统。回声定位脉冲由喉部的振动膜产生，并通过鼻子或嘴巴发出，具体取决于物种。某些物种的鼻叶可能会传导声音。

   Research has provided some information on the mechanisms of bat sonar. There is evidence that the multiple frequencies of FM or harmonic patterns serve in determining target direction. The relative intensities of the various frequencies are different at each ear, which allows the animal to determine the target’s direction when three or more frequencies are received. Target velocity may be measured by CF bats through the use of the Doppler shift, a change in perceived frequency due to the relative motion of the bat and its target. Changes in pulse-echo timing may provide information on target distance and velocity. The ratio of useful signal to background noise is increased by several mechanisms, including specializations of the middle ear and its ossicles (tiny bones), isolation of the cochlea (the area where sound energy is converted into nerve impulses), and adaptations of the central nervous system.

   研究为蝙蝠声纳的机理提供了一些信息。有证据表明，调频或谐波模式的多个频率用于确定目标方向。每只耳朵上不同频率的相对强度不同，这使得动物能够在接收到三个或更多频率时确定目标的方向。CF蝙蝠可以通过使用多普勒频移来测量目标速度，多普勒频移是由于蝙蝠与其目标的相对运动而导致的感知频率变化。脉冲回波定时的变化可以提供关于目标距离和速度的信息。有用信号与背景噪声的比率通过多种机制增加，包括中耳及其听骨（小骨）的特殊化、耳蜗的隔离（声能转换为神经冲动的区域）以及中枢神经系统的适应。

Senses

   In folklore, bats have been considered to be blind. In fact, the eyes in the Microchiroptera are small and have not been well studied. Among the Megachiroptera the eyes are large, but vision has been studied in detail only in flying foxes. These bats are able to make visual discriminations at lower light levels than humans can. The Megachiroptera fly at night, of course, and some genera fly below or in the jungle canopy, where light levels are very low. Except for rousette bats (Rousettus), none are known to orient acoustically.

   Studies of several genera of Microchiroptera have revealed that vision is used in long-distance navigation and that obstacles and motion can be detected visually. Bats also presumably use vision to distinguish day from night and to synchronize their internal clocks with the local cycle of daylight and darkness.

   The senses of taste, smell, and touch in bats do not seem to be strikingly different from those of related mammals. Smell is probably used as an aid in locating fruit and flowers and possibly, in the case of vampire bats, large vertebrates. It may also be used for locating an occupied roost, members of the same species, and the differentiation of individuals by sex. Many bats depend upon touch, aided by well-developed facial and toe whiskers and possibly by the projecting tail, to place themselves in comforting body contact with rock surfaces or with other bats in the roost.

感官

   在民间传说中，蝙蝠被认为是盲人。事实上，微翅目昆虫的眼睛很小，尚未得到很好的研究。在翼手目中，眼睛很大，但只有在飞狐中才对视力进行了详细研究。这些蝙蝠能够在比人类更低的光线下进行视觉辨别。当然，大翅目昆虫在夜间飞行，有些属在丛林树冠下或丛林树冠中飞行，那里的光照水平非常低。除了罗塞特蝙蝠（Rousettus）之外，没有一种已知的蝙蝠能够在声学上定向。

   对几属微翅目昆虫的研究表明，视觉用于远距离导航，障碍物和运动可以通过视觉检测。蝙蝠也可能利用视觉来区分白天和黑夜，并使其内部时钟与当地的昼夜周期同步。

   蝙蝠的味觉、嗅觉和触觉似乎与相关哺乳动物没有明显区别。气味可能被用来帮助定位水果和花朵，对于吸血蝙蝠来说，也可能是大型脊椎动物。它也可用于定位被占用的栖息地、同一物种的成员以及按性别区分个体。许多蝙蝠依靠触觉，借助于发达的面部和脚趾胡须，可能还有突出的尾巴，使自己与岩石表面或栖息中的其他蝙蝠进行舒适的身体接触。

3.3 “光速极限”与“声速极限”

   “对几属微翅目昆虫的研究表明，视觉用于远距离导航，障碍物和运动可以通过视觉检测。蝙蝠也可能利用视觉来区分白天和黑夜，并使其内部时钟与当地的昼夜周期同步。”

   对于同时能够使用“光”、“声”进行感知的蝙蝠，在不同的条件下同时受到“光速极限”与“声速极限”的限制。

   这些蝙蝠的逻辑学是怎样的？它们的飞行速度能超过声速吗？

   或者说，这些蝙蝠运动速度超过声速时，外在空间的感知结果是怎样的？会不会引起“回声定位”信号与“视觉”信号之间的矛盾？

   过去的历史表明：

   （1）把物理学归结为数学，是不可行的；物理学不能归结为数学。

   （2）把数学归结为逻辑，同样是不可行。数学不能归结为逻辑。

   以至于著名数学家阿诺德（Влади́мир И́горевич Арно́льд, 英文 Vladimir Igorevich Arnold, 1937-06-12 ~ 2010-06-03）在 1998年之前还公然声称：

   “Mathematics is a part of physics. Physics is an experimental science, a part of natural science. Mathematics is the part of physics where experiments are cheap.”

   “数学是物理的一部分。物理是实验科学，是自然科学的一部分，数学是物理中实验便宜的部分。”

Vladimir Igorevich Arnold. On teaching mathematics [J]. Russian Mathematical Surveys, 1998, 53(1): 229-234.

doi:  10.1070/RM1998v053n01ABEH000005

https://iopscience.iop.org/article/10.1070/RM1998v053n01ABEH000005

   物理学，正如大数学家希尔伯特所说：“物理对于物理学家来说实在是太难了！”

科学网，2019-05-14，曹则贤：世界上80％的物理学家根本不懂物理

https://news.sciencenet.cn/htmlnews/2019/5/426211.shtm

图1  阿诺德，Владимир Игоревич Арнольд, Vladimir I Arnol'd,  Vladimir Igorevich Arnold, 1937-06-12 ~ 2010-06-03

https://rs.resalliance.org/wp-content/uploads/2010/06/Vladimir_Arnold-1.jpg

图2  希尔伯特, David Hilbert, 1862-01-23 ~ 1943-02-14

https://www.britannica.com/biography/David-Hilbert

https://cdn.britannica.com/91/124791-004-B2DE3FCC/David-Hilbert.jpg?s=1500x700&q=85

图3  爱因斯坦, 1879-03-14 ~ 1955-04-18 凌晨1点15分

图4  罗塞特蝙蝠（Rousettus）, Egyptian fruit bat, Egyptian rousette (Rousettus aegyptiacus)

http://animal.memozee.com/view.php?tid=3&did=41083&mode=full

http://animal.memozee.com/ArchOLD-8/1492679123.jpg

图5  罗塞特蝙蝠（Rousettus）, Rousettus aegyptiacus (E. Geoffroy, 1810) - Egyptian Fruit Bat, male

https://www.biolib.cz/en/image/id173707/

https://www.biolib.cz/IMG/GAL/173707.jpg

参考资料：

[1] 2023-01-12，翼手目/bats/冯江，中国大百科全书，第三版网络版[ED/OL]

https://www.zgbk.com/ecph/words?SiteID=1&ID=173337&Type=bkzyb&SubID=138631

[2] bat , mammal, Britannica

https://www.britannica.com/animal/bat-mammal/Classification

[3] Quotations by Henri Poincaré

https://mathshistory.st-andrews.ac.uk/Biographies/Poincare/quotations/

   If geometry were an experimental science, it would not be an exact science. it would be subject to continual revision ... the geometrical axioms are therefore neither synthetic a priori intuitions nor experimental facts. They are conventions. Our choice among all possible conventions is guided by experimental facts; but it remains free, and is only limited by the necessity of avoiding every contradiction, and thus it is that postulates may remain rigorously true even when the experimental laws which have determined their adoption are only approximate. In other words the axioms of geometry (I do not speak of those of arithmetic) are only definitions in disguise. What then are we to think of the question: Is Euclidean geometry true? It has no meaning. We might as well ask if the metric system is true and if the old weights and measures are false; if Cartesian coordinates are true and polar coordinates are false. One geometry cannot be more true than another; it can only be more convenient.

[4] 华罗庚. 从单位圆谈起[M]. 北京:  科学出版社, 1977-02.

https://baike.baidu.com/item/%E4%BB%8E%E5%8D%95%E4%BD%8D%E5%9C%86%E8%B0%88%E8%B5%B7?fromModule=lemma_search-box

[5] 科学网，2021-06-17，当测试广义相对论时，微小建模误差能快速累积

https://news.sciencenet.cn/htmlpaper/2021/10/202110111018314267031.shtm

   如果一个目录中有10到30个事件，而信噪比为20（这对于此类测试中使用的事件来说很典型），就可能产生偏离广义相对论的误导，错误地指向根本不存在的新物理现象。因为这接近于目前用来评估爱因斯坦理论的目录的大小，作者认为物理学家在进行这样的实验时应该谨慎。

[6] Christopher J. Moore, Eliot Finch, Riccardo Buscicchio, Davide Gerosa. Testing general relativity with gravitational-wave catalogs: The insidious nature of waveform systematics. iScience, 2021, 24(6): 102577. DOI10.1016/j.isci.2021.102577. JUN 25 2021

https://www.cell.com/iscience/fulltext/S2589-0042(21)00545-9

http://dx.doi.org/10.1016/j.isci.2021.102577

[7] 2022-01-20，棕果蝠/leschenault's rousette/金龙如，中国大百科全书，第三版网络版[ED/OL]

https://www.zgbk.com/ecph/words?SiteID=1&ID=173341&Type=bkzyb&SubID=140701

   具有特殊的舌敲击回声定位能力。棕果蝠的这种回声定位和其他喉回声定位蝙蝠具有极大差别，喉回声定位蝙蝠通过喉部发出超声波，而棕果蝠通过舌在口腔中左右敲击发出的超声波进行回声定位，这种舌敲击的回声定位声波持续时间短，平均为5毫秒，但是带宽较宽，最大能量处频率为30～45千赫兹（图3）。

[8] 科普中国，2021-12-31，回声定位法

https://www.kepuchina.cn/article/articleinfo?business_type=100&classify=1&ar_id=339102

   人回声定位术是当声波碰到一个障碍物(如悬崖)时，它会弹回来，我们会再听到这个声音。这种反射回来的声音称为回声。在户外空旷的地方，回声比较模糊，因为声音的震动会向四处散开，能量会散失。而在一个密闭的空间里(如隧道)，反射的声音不会跑掉，所以回声很大。

   蝙蝠、海豚、鲸等动物发出高声音，根据回声来判断物体方位及距离，从而在黑暗中行进、觅食。以蝙蝠为例，它们既能发出超声波，又能听到超声波。蝙蝠先向周围环境发出超声波，超声波遇物反弹被它们听到。通过“测量”声波返回的时间，蝙蝠确定物体与自己之间距离，进而在漆黑洞穴中自如穿梭猎食。从中获得启发的“人回声定位术”获得专家肯定。

相关链接：

[1] 2017-07-09，[随感] 物理学是物理学；数学是数学。物理学不能归结为数学

https://blog.sciencenet.cn/blog-107667-1065389.html

[2] 2022-11-20，[？] 《三体3：死神永生》：黑域，狭义相对论、朗道与华罗庚

https://wap.sciencenet.cn/blog-107667-1364551.html

[3] 2023-02-15，[专业微信群贴出] “静止”的宏观点电荷会激发出磁场，并发射出电磁波吗？

https://blog.sciencenet.cn/blog-107667-1376384.html

[4] 2019-07-02，记忆：南开大学2008年《科学素质教育课程骨干教师高级研修班》

https://blog.sciencenet.cn/blog-107667-1187783.html

[5] 2023-01-11，[简历] 昨天在某微信群里的自我介绍

https://blog.sciencenet.cn/blog-107667-1371528.html

[6] 2020-10-04，[优先权？] 中国人首先提出 SI 基本单位“安培”新定义？

https://blog.sciencenet.cn/blog-107667-1253168.html

[7] 2022-07-31，[重贴] 反思麦克斯韦经典电磁理论宣言（附说明）

https://blog.sciencenet.cn/blog-107667-1349475.html

[8] 2021-01-13，[建议] 广泛重复自然科学各个学科中100多年前的那些经典实验

https://blog.sciencenet.cn/blog-107667-1267037.html

[9] 2022-09-28，历史上经典科学实验的现代再检验：“硬凑”的逻辑

https://blog.sciencenet.cn/blog-107667-1357231.html

[10] 2020-10-08，[严肃内容] 黑洞、电磁黑洞（静电黑洞）、联合黑洞（黑洞+电磁黑洞），统一场“黑洞”

https://blog.sciencenet.cn/blog-107667-1253596.html

[11] 2017-10-12，灭绝漏斗、电磁洞已经被观察到（牛顿苹果）：卡片机傻拍2017（144）

https://blog.sciencenet.cn/blog-107667-1081041.html

[12] 2017-10-10，终极洞、灭绝漏斗、引力屏蔽与“统一场”

https://blog.sciencenet.cn/blog-107667-1079968.html

[13] 2013-04-01，[请教] 类星体quasar周围有静电场吗？

https://blog.sciencenet.cn/blog-107667-675940.html

[14] 2012-12-12，电荷真伟大（打油）

https://blog.sciencenet.cn/blog-107667-641876.html

[15] 2012-12-08，[请教] 俺感兴趣的物理学研究

https://blog.sciencenet.cn/blog-107667-640566.html

[16] 2011-04-26，[请教] 电子、质子、中子的内部结构

https://blog.sciencenet.cn/blog-107667-437507.html

[17] 2015-08-25，物理学“狭义相对性原理”的准确表述

https://blog.sciencenet.cn/blog-107667-915813.html

[18] 2022-09-29，统一场：爱因斯坦是“超级冤大头”吗？

https://blog.sciencenet.cn/blog-107667-1357360.html

[19] 2021-09-11，[求助] 三根平行载流导线之间的洛伦兹力，怎么计算？

https://blog.sciencenet.cn/blog-107667-1303778.html

[20] 2021-04-10, 建议用物理实验精确测量多平行导线之间的电磁作用力.

https://osf.io/473du/

Preprint DOI:  10.31219/osf.io/473du

[21] 2020-03-24，[呼吁] 电磁波依赖参照系的判定实验

http://blog.sciencenet.cn/blog-107667-1225059.html

[22] 2019-03-03，[悖论] 物理学里的“惯性系”无法定义吧？

https://blog.sciencenet.cn/blog-107667-1165369.html

[23] 2013-04-12，[请教] 物理问题：“坐标系的变换不会影响结果”

http://blog.sciencenet.cn/blog-107667-679557.html

[24] 2010-09-27，[讨论]“直角坐标系”和“极坐标系”的差别

http://blog.sciencenet.cn/blog-107667-367547.html

[25] 2021-08-28，[数学与物理] 一元二次方程、圆锥曲线、正态分布

https://blog.sciencenet.cn/blog-107667-1301802.html

[26] 2022-10-12，[答疑，备课，坍缩] 正弦量合情合理地变成相对静止的矢量，一点也不奇怪

https://blog.sciencenet.cn/blog-107667-1359135.html

[27] 2013-12-07，数学是严谨的吗？（1 历史事实）

https://blog.sciencenet.cn/blog-107667-747843.html

[28] 2013-12-11，数学是严谨的吗？（2 逻辑是元凶）

https://blog.sciencenet.cn/blog-107667-749077.html

[29] 2013-12-12，数学是严谨的吗？（3 一个形象的比喻）

https://blog.sciencenet.cn/blog-107667-749285.html

[30] 2010-03-10，逻辑方法的局限性：元知识、乌龟塔与盲人摸象

https://blog.sciencenet.cn/blog-107667-301534.html

感谢您的指教！

感谢您指正以上任何错误！

感谢您提供更多的相关资料！