戴榕菁
还记得科普作家们或甚至如霍金那样的科学大咖给你讲的如何跌进黑洞的故事吗？他们告诉你说，那将是一个非常漫长的过程，甚至可以好似无限长，这是因为黑洞的巨大的引力会造成引力时间膨胀（Gravitational Time Dilation）【[1]】从而导致黑洞附近的时间变得非常地慢，直至无限慢。。。。非常童话，非常浪漫，呵呵。
而真相却要骨感的多：黑洞的引力再大也无法改变时间的进度，所以如果谁要体验一下跳进黑洞那漫长过程的话，游戏会令他意外地很快就结束了。
事实上，1912年爱因斯坦在一篇题为“The speed of light and the statics of the gravitational field”【[2]】的文章中给出了下面这个公式：
(1)
其中m和m’是两个物体的质量，c是真空中的光速，k是引力常数（constant of gravitation），R是两物体之间的距离，而ω则是当m’固定时m绕m’运动的角速度。假设m’是太阳，m是地球的话，那么我们就可以将1/ω看成是记录一年四季变化时间的记录，ω越大时间过的越快，ω越小时间过的越慢。实际爱因斯坦直接将之称为引力钟（gravitational clock）。
由(1)可以看出，如果按今天的广义相对论学者的说法光速c即便在重力场中也是不变量的话，那么很显然时间ω不但不会发生引力膨胀，而且会随着引力的增加而迅速变的更快。
当然，1912年的爱因斯坦认为光速c在引力场中是变化的。但由(1)式可以看出，要想让时间随着引力增大而变慢的话，光速c必须以高于二次方的速度随引力的增大而减小。这意味着从距离地球300公里的太空站向地球发一束光到达地面时它的速度已经减少了十分之一；或者说月球上的光速要比地球上快很多倍才能保证月球上的时间不会比地球慢。。。。假如这样的天方夜谭是真的而地球科学们至今都没有发现，那也太菜了吧！。。。。。。
随着狭义相对论被推翻以及与之相关的相对论时间膨胀（time dilation）（注：虽然引力时间膨胀是广义相对论的内容，但却是由于其中的狭义相对论元素造成的）被否定，不但量子力学要面临极大的风暴，连作为现代宇宙学和天体物理学的核心内容的黑洞理论恐怕也会经历一场雪崩。。。。。。
[[1]] Rain, R. “Gravitational Time Dilation Calculator”. Reviewed by Dominik Czernia, PhD and Jack Bowater. Last updated: Nov 17, 2022. Retrieved from: https://www.omnicalculator.com/physics/gravitational-time-dilation
[[2]] Einstein, A. (1912). “The speed of light and the statics of the gravitational field”. Translated by D. H. Delphenich.“Lichtgeschwindigkeit und Statik des Gravitionsfeldes,” Ann. Phys. (Leipzig) 38 (1912), 355-369. Available at: http://neo-classical-physics.info/uploads/3/4/3/6/34363841/einstein_-_speed_of_light_and_grav.pdf
HARRISON在上面的对话中没有直接提到Shapiro,不过在他对话中提到的文章”Basics of Post Newtonian Gravity“中有Shapiro实验：
Galileo and Tycho Brahe made extensive astronomical observationswhich led Kepler to formulate his laws of planetary motion. All theseobservations were of relative motion. This led Newton to propose his theory ofgravity, which could just as well have been expressed in a form that does notinvolve the concept of force. The approach in this paper extends the Newtoniantheory and the special theory of relativity by including relative velocity basedon the form of the measured data and also by comparison with electromagneticeffects. Application of the new single equation to the precession of the perihelion of Mercury, the gravitational deflection of light, the Shapiro timedelay, the Schwarzschild radius and the last stable orbit gives results whichagree with those of general relativity. Gravitational waves are also discussed.This approach could be used to determine non-Newtonian variations in thetrajectories of satellites
北航一位名叫Tony Yuan的人在academia.com贴出一篇题为“Exploring the Accelerating Expansion of the Universe”的讨论文章：
https://www.academia.edu/s/1a5b08b8da#comment_1355327
我偶尔点进去看到有一人的评论提到那个所谓的证明重力时间膨胀的著名的Shapiro实验，我就跟复的一贴指出时间从来不会膨胀，其中我就引用了本文中提到的爱因斯坦1912年的公式。
当时该讨论显示还有一个月才结束，想必北航人不缺钱。。。所以我还等着那位提到Shapiro实验的人会回复我的跟帖，但隔天，该讨论就结束了。。。
只有两方能提前结束一个讨论：Tony Yuan本人，或academia.com
提前结束的动机可能有两种：1）因为结束后之前没有参与讨论的人好像就不能再进去了，所以提前结束可能是为了不让更多的人看到讨论的内容；2）结束前，参与讨论的人仍可以修改自己的发言，结束后谁也不能再做修改，所以提前结束可能是将已有的发言冻结。
上面两种可能代表着完全相反的态度。前者是害怕更多的人看到已有的讨论，后者是将已有的发言冻结留着给已参与讨论的人及可能的后人看。。。。
你们认为是哪种可能呢？下面是那段对话：
H R HARRISON
7 days ago
Dear Tony Yuan,
My first responce to your paper is related to the mention of the speed of gravity. As shown in my Basics of Post Newtonian Gravity ( found in my profile) I initialy reagrd ti speed of gravity to be the same the speed of light in mass free space.. The first additional term in my equation is based on eletromagnetics and is normal to the relavive velocity. This gives the accepted results on the precession of orbits in the Solar system. But there are a few other measurable effects that are not predicted. Another term is added wich acts in the direction of the relative velocity. The new equation now predictes all the well verified phenomena. The equation now predicts that the speed of light is reduced when passing through a gravity field. The speed of gravity is still constant.
I have not found any way to test my ewuation when applied to dynamics outside the Solar system. Also I do not believe that your equations will work for the Solar system.
H Ron Harrison
Like1
Rongqing Dai
7 days ago
About the so-called Shapiro delay, delay is the observed fact but the so-called time-dilation is just the tale....
The delay could be most plausibly caused by the longer path when light grazing the Sun, and maybe arguably the slower speed of light as well as your theory claims, but definitely not the dilation of time.
Concerning the change of the speed of light in gravitational field, by Newtonian, we could expect that the speed of light would increase when approaching the massive object and decrease when departing the massive object instead of the opposite!
Einstein claims in his 1912 article that [A clock will run faster when we bring it to a location where c is greater] which is consistent to the famous GR claim that time runs slower in gravity if the speed of light decreases in gravity as your theory claims.....but Einstein also contradicted this with the following formula in the same 1912 article:
m ω^2 R = c^2 k mm’ /4πR^3 (1)
where m is the mass of the object circulating another mass m', R is the distance, and ω is the angular velocity of m circulating m'. Now if m is the Earth, m' is the Sun, then ω would be the clock of ancient people around world to count seasons and years!
From (1) we can conclude that the closer to a massive object, the faster the clock if the speed of light is constant, which contradicts the famous nowadays GR claim (which assumes a constant speed of light anywhere) that time goes slower in gravity.
Of course, now you can say that a decreased speed of light would make (1) not contradict to the famous GR claim......but obviously a linear decrease would not do the job, even quadratically decrease would not be enough since that would only make ω independent of R, not increase with R.
The problem is that if the speed of light would decrease faster than quadratically as gravity increases, we should have observed this effect in our earth environment, shouldn't we?
