Re: [閒聊] 廣義相對論文章
※ 引述《s1290961 (煦)》之銘言：
: 最近寫了一篇談廣相的文章，
: 有興趣的話歡迎閱讀、討論。
: https://sciencebrunch.wordpress.com/2016/01/22/%E9%80%9A%E5%BE%80%E5%BB%A3%E7%BE%A9%E7%9B%B8%E5%B0%8D%E8%AB%96%E4%B9%8B%E8%B7%AF%E2%94%80%E2%94%80%E7%89%9B%E9%A0%93%E3%80%81%E9%A6%AC%E8%B5%AB%E3%80%81%E6%84%9B%E5%9B%A0%E6%96%AF%E5%9D%A6/
: 縮網址：https://goo.gl/BMXMgw
稍微看一下寫得還蠻認真很仔細的,不過有些地方我覺得有點問題提出來跟板友
分享看看,首先我們要知道以現代的廣義相對論來看Mach原理跟廣義相對論是不太一樣
的喔,Mach原理對愛因斯坦的確早期有啟發性的關鍵,但是後來這二個發展是不太一樣的
這二件事情是要被分開看待的,而且二者都有實驗來驗證,愛因斯坦廣相實驗的全部被證實
目前學術界的看法是支持愛因斯坦的廣義相對論而不支持Mach原理
Mach原理是說
不存在絕對時空,慣性系是物體相對於宇宙整體的平均做加速運動的座標系
而物體的慣性效應是由於宇宙間星系的物質分布和運動所決定
那Mach原理所導致的必然結果是
1.在比較重的物體,物體的慣性應該增加
2.當周圍的物體加速運動時候,此物體應該受到與此物體加速度同樣方向的加速度方向
後來1960年代有二個物學家Vernon W. Hughes和 Ronald Drever 做了質量各異
向性的實驗來驗證Mach原理
https://en.wikipedia.org/wiki/Hughes%E2%80%93Drever_experiment
Vernon W. Hughes et al. (1960)[3] and Ronald Drever (1961)[4] independently
conducted similar spectroscopic experiments to test Mach's principle. However,
they didn't use the Mossbauer effect but made magnetic resonance measurements
of the nucleus of lithium-7, whose ground state possesses a spin of 3/2. The ground state is split into four equally spaced magnetic energy levels when measured in a magnetic field in accordance with its allowed magnetic quantum number. The nuclear wave functions for
the different energy levels have different spatial distributions relative to
the magnetic field, and thus have different directional properties.
If mass isotropy is satisfied, each transition between a pair of adjacent
levels should emit a photon of equal frequency, resulting in a single, sharp
spectral line.
On the other hand, if inertia has a directional dependence, a triplet or
broadened resonance line should be observed. During the 24-hour course of
Drever's version of the experiment, the Earth turned,and the magnetic field
axis swept different sections of the sky. Drever paid particular attention to
the behavior of the spectral line as the magnetic field crossed the center of
the galaxy.[A 7] Neither Hughes nor Drever observed any frequency shift of the
energy levels, and due to their experiments' high precision, the maximum
anisotropy could be limited to 0.04 Hz = 10^-25 GeV.
簡單來說就是
Mach原理認為是認為較大質量的物體假設較大慣性效應,那假設這大質量是銀河系
且銀河系質量各異向性的,則粒子朝著銀河系和離開銀河系慣性質量會稍有不同
Hughes和Drever用lithium-7做實驗觀察在H=4700 Gauss的磁場下原子核的共振光譜
根據Zeeman效應,磁量子數 J=3/2在磁場中分裂有 m_J= 3/2,1/2,-1/2,-3/2四條光譜
如果慣性質量是量各異向性的,則這四個態是不等間隔的,因為不同的m_J相當於磁偶極矩
對磁場有不同的方向,則電子有不同的運動方向,則這四個光譜間隔距離應該是不一樣
但是並沒有量到這個效應.
事實上還有一個理論是更希望超越廣義相對論來支持Mach原理,就是著名的
Dicke-Brans理論,這是科學史上著名的典範理論,就是這理論很美但是實驗並不支持
有機會在po一篇orz
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※ 文章網址: https://www.ptt.cc/bbs/Physics/M.1453972291.A.D0F.html
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