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[讨论] 电磁学的实验再检验(7):电磁波的刚性(关联“光压”)
特斯拉: 今天的科学家们用数学替换了实验,并且他们从方程到方程来回地推导,最终建立了一个和现实世界没有任何关系的数学结构。
https://www.rastko.rs/projekti/tesla/delo/10884
阿诺德: 推导的链(即所谓的“证明”)越长越复杂,最后得到的结论可靠性越低。
https://iopscience.iop.org/article/10.1070/RM1998v053n01ABEH000005
费米: 我更喜欢的方式,是对你正在计算的过程有一个清晰的物理图像。
https://www.nature.com/articles/427297a
所以,判定实验原理的设计,越接近“被检验的描述物理作用的数学公式”越好。
这是一个陆续思考的过程,十分艰难的过程。是电场、磁场、电磁波深层次性质探索的实体物理实验。要求极高的实验精度、稳定性。
先给出“定性”图像。假如可行,再进行“定量”细化。最后才是实体实验装置的具体设计。
术语 terminology
电磁波: electromagnetic wave
光压: light pressuret
动量: momentum
刚性: stiff
刚度: stiffness
核心:
假如“光压”存在(我想这个没问题),根据“作用力 = 反作用力”,
光线也应该受到来自物体的“反作用力”。
一、费曼是个真科学家
图1 费曼,1965年诺贝尔物理学奖得主
https://www.nobelprize.org/prizes/physics/1965/feynman/facts/
https://www.nobelprize.org/prizes/physics/1965/summary/
费曼(Richard Phillips Feynman),1965年诺贝尔物理学奖得主。
1974年在加州理工学院的一场毕业典礼上,“真科学家”费曼说到:
“ I'm talking about a specific, extra type of integrity that is not lying, but bending over backwards to show how you're maybe wrong, that you ought to have when acting as a scientist. And this is our responsibility as scientists, certainly to other scientists, and I think to laymen.
【机器翻译】我说的是一种特殊的、额外的正直,不是撒谎,而是竭尽全力表明你可能错了,这是你作为一名科学家应该具备的。这是我们作为科学家的责任,当然是对其他科学家的责任。”
https://sites.cs.ucsb.edu/~ravenben/cargocult.html
https://calteches.library.caltech.edu/51/2/CargoCult.htm
在费曼物理学讲义的“27 Field Energy and Field Momentum”里,费曼写到:
“It is interesting that there seems to be no unique way to resolve the indefiniteness in the location of the field energy. It is sometimes claimed that this problem can be resolved by using the theory of gravitation in the following argument. In the theory of gravity, all energy is the source of gravitational attraction. Therefore the energy density of electricity must be located properly if we are to know in which direction the gravity force acts. As yet, however, no one has done such a delicate experiment that the precise location of the gravitational influence of electromagnetic fields could be determined. That electromagnetic fields alone can be the source of gravitational force is an idea it is hard to do without. It has, in fact, been observed that light is deflected as it passes near the sun—we could say that the sun pulls the light down toward it. Do you not want to allow that the light pulls equally on the sun? Anyway, everyone always accepts the simple expressions we have found for the location of electromagnetic energy and its flow. And although sometimes the results obtained from using them seem strange, nobody has ever found anything wrong with them—that is, no disagreement with experiment. So we will follow the rest of the world—besides, we believe that it is probably perfectly right.
【机器翻译】有趣的是,似乎没有唯一的方法来解决场能量位置的不确定性。有时有人声称,这个问题可以通过以下论点中的引力理论来解决。在引力理论中,所有的能量都是引力的来源。因此,如果我们想知道重力作用的方向,就必须正确地确定电的能量密度。然而,到目前为止,还没有人做过如此精细的实验来确定电磁场引力影响的精确位置。只有电磁场才能成为引力的来源,这是一个很难没有的想法。事实上,人们已经观察到,当光线经过太阳附近时会发生偏转——我们可以说是太阳把光线拉向它。你不想让光线在太阳上产生同样的拉力吗?不管怎样,每个人总是接受我们所发现的关于电磁能的位置及其流动的简单表达式。尽管有时使用它们得到的结果看起来很奇怪,但没有人发现它们有任何问题,也就是说,与实验没有分歧。因此,我们将追随世界其他地方,此外,我们相信这可能是完全正确的。”
核心是“As yet, however, no one has done such a delicate experiment that the precise location of the gravitational influence of electromagnetic fields could be determined. That electromagnetic fields alone can be the source of gravitational force is an idea it is hard to do without. It has, in fact, been observed that light is deflected as it passes near the sun—we could say that the sun pulls the light down toward it. Do you not want to allow that the light pulls equally on the sun? 【机器翻译】然而,到目前为止,还没有人做过如此精细的实验来确定电磁场引力影响的精确位置。只有电磁场才能成为引力的来源,这是一个很难没有的想法。事实上,人们已经观察到,当光线经过太阳附近时会发生偏转——我们可以说是太阳把光线拉向它。你不想让光线在太阳上产生同样的拉力吗?”
二、从“光压”到“电磁波的刚性”
图2 费米,1938年诺贝尔物理学奖得主
https://www.nobelprize.org/prizes/physics/1938/summary/
费米: 我更喜欢的方式,是对你正在计算的过程有一个清晰的物理图像。One way, and this is the way I prefer, is to have a clear physical picture of the process that you are calculating.
https://www.nature.com/articles/427297a
“光波照射到物体上对物体表面产生的辐射压强。由于电磁场具有动量,其入射到物体上时会对物体施加一定的压强,这种压强称为辐射压强。”
https://www.zgbk.com/ecph/words?SiteID=1&ID=133534&Type=bkzyb&SubID=95643
图3 光压的示意图
Physicists make first observation of the pushing pressure of light
https://scx2.b-cdn.net/gfx/news/2015/pressureofli.jpg
https://phys.org/news/2015-06-physicists-pressure.html
于是,上面电磁场的“动量”在“对物体施加一定的压强”时,电磁波自身会不会受到来自“物体”的反作用力?假如存在这种反作用力,它会通过电磁波自身向光源方向“逆向”传递吗?
借用“光子”概念:光子与物体碰撞后,该光子动量的变化,会影响后面来自光源的其它光子吗?
通俗些,就是:电磁波自身是否具有刚性?
一个类比的直观说明:消防员喷水顶墙。
图4 消防员喷水顶墙
https://holooly.com/wp-content/uploads/2020/10/rrrr.png
如上图。连续喷出的水柱,在遇到墙壁阻挡时,消防员从手握的水龙头上可以感觉到墙壁产生的反作用力。此时,比喷到空气中的阻力更大。
简言之:连续运动的水柱具有一定的刚性,能够传递机械作用力。
水在相对运动情况下的刚性/刚度,与“相对运动的速度”成正比。
类似地,光或电磁波也有类似的现象吗?
光遇到物体(固体),会产生光压。这种光与固体的相互作用,会通过光线(电磁波)往回传递吗?
三、电磁波的刚性:判决实验的原理
图5 电磁波的刚性:判决实验的原理
一束激光,与反射镜夹角为 45°。它形成“反射物体”的“入射光线”。
(1)改变“反射物体”对水平方向的夹角 θ,测量反射镜的空间位移变化。
(2)用对电磁波吸收率不同的材料作为“反射物体”,重复上面的实验。
(3)改变激光的频率,重复上面的实验。
(4)以上各种情况下,反射光线的频率的变化。
(5)对照,无反射物体。忽略掉各种次要因素,对应“电磁波无刚性”的情况。
图6 电磁波的刚性:判决实验的原理,无反射物体。
假如“电磁波具有刚性”,则“反射镜”会出现一定的空间位置变化。
参考资料:
[1] Freeman Dyson. A meeting with Enrico Fermi [J]. Nature, 2004, 427(6972): 297-297.
doi: 10.1038/427297a
https://www.nature.com/articles/427297a
“There are two ways of doing calculations in theoretical physics”, he said. “One way, and this is the way I prefer, is to have a clear physical picture of the process that you are calculating. The other way is to have a precise and self-consistent mathematical formalism. You have neither.”
[2] Richard P. Feynman, The Nobel Prize in Physics 1965
https://www.nobelprize.org/prizes/physics/1965/summary/
https://www.nobelprize.org/prizes/physics/1965/feynman/facts/
[3] Richard Phillips Feynman, MacTutor History of Mathematics archive
https://mathshistory.st-andrews.ac.uk/Biographies/Feynman/
[4] Cargo Cult Science, Richard Feynman. From a Caltech commencement address given in 1974. Also in Surely You're Joking, Mr. Feynman!
https://sites.cs.ucsb.edu/~ravenben/cargocult.html
https://calteches.library.caltech.edu/51/2/CargoCult.htm
[5] 2022-01-20,费米,E./Fermi, Enrico/戴念祖,中国大百科全书,第三版网络版[DB/OL]
https://www.zgbk.com/ecph/words?SiteID=1&ID=123684&Type=bkzyb&SubID=61860
为纪念他的贡献,原子序数为100的元素,以他的姓氏命名为镄。美国原子能委员会设立了费米奖金。费米对统计物理、原子物理、原子核物理、粒子物理都有重要贡献。
费米对理论物理和实验物理都做出了重要的贡献。
[6] Enrico Fermi, The Nobel Prize in Physics 1938
https://www.nobelprize.org/prizes/physics/1938/summary/
[7] 2022-01-20,光压/light pressure/胡望雨、方哲宇,中国大百科全书,第三版网络版[DB/OL]
https://www.zgbk.com/ecph/words?SiteID=1&ID=133534&Type=bkzyb&SubID=95643
[8] 27 Field Energy and Field Momentum, The Feynman Lectures on Physics, Volume II
https://www.feynmanlectures.caltech.edu/II_27.html
[9] The Feynman Lectures on Physics
https://www.feynmanlectures.caltech.edu/
[10] 2023-04-04,刚度/stiffness/姚振汉、陈明继,中国大百科全书,第三版网络版[DB/OL]
https://www.zgbk.com/ecph/words?SiteID=1&ID=219824&Type=bkzyb&SubID=63697
[11] 2022-12-29,光功能晶体/optical function crystals/胡强强、陶绪堂,中国大百科全书,第三版网络版[DB/OL]
https://www.zgbk.com/ecph/words?SiteID=1&ID=60452&Type=bkzyb&SubID=80474
在外场(如电、光、磁、热、声、力等)作用下,利用晶体本身光学性质(如折射率、感应电极化或非线性效应等)发生变化的机理,实现对入射光信号的获取、调制、传输、显示、受激发射、能量或频率转换等目的的光学晶体。
相关链接:
[1] 2022-05-16,[讨论] 电磁波会传递机械力或电磁力吗?
https://blog.sciencenet.cn/blog-107667-1338778.html
[2] 2023-07-22,[请教] 电磁学的实验再检验(6):“电力线 electric field lines”本身带有记号(ID)吗?
https://blog.sciencenet.cn/blog-107667-1396267.html
[3] 2023-07-21,[呼吁] 电磁学的实验再检验(5):静电力(库仑定律)扭秤法的高精度再检验
https://blog.sciencenet.cn/blog-107667-1396160.html
[4] 2023-07-20,[讨论] 电磁学的实验再检验(4):电磁波依赖坐标系判定实验原理
https://blog.sciencenet.cn/blog-107667-1396060.html
[5] 2023-07-15,[求助] 电磁学的实验再检验(3):电磁波依赖坐标系实验
https://blog.sciencenet.cn/blog-107667-1395495.html
[6] 2023-07-14,[最主流] 电磁学的实验再检验(2):平行载流导线之间的电磁力
https://blog.sciencenet.cn/blog-107667-1395383.html
[7] 2023-07-13,[最主流] 电磁学的实验再检验(1):坡印廷矢量(Poynting vector)只是一种数学抽象?
https://blog.sciencenet.cn/blog-107667-1395225.html
[8] 2022-06-13,[讨论] 引力、电磁力“独立性”的判定实验
https://blog.sciencenet.cn/blog-107667-1342826.html
[9] 2022-03-30,[傻问] 磁场变化能产生电荷吗?
https://blog.sciencenet.cn/blog-107667-1331747.html
[10] 2022-06-14,[小结] 近期关于引力、电磁力统一的思考
https://blog.sciencenet.cn/blog-107667-1342966.html
[11] 2022-06-25,[小结] 我们在物理学上的主要“创新点”(?)
https://blog.sciencenet.cn/blog-107667-1344493.html
[12] 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
[13] 2023-07-14,“电磁学的实验再检验”:经典电磁学实验当代再检验的起因、意义要点
https://blog.sciencenet.cn/blog-107667-1395251.html
[14] 2023-07-12,[惊悚、惊喜] 原来我才是“最主流”:反思麦克斯韦经典电磁理论
https://blog.sciencenet.cn/blog-107667-1395113.html
[15] 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
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