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Books by David Michalets
With Forces and Light
7 Eddington Experiment
This is section 7 of 12 in the web-book.
This experiment was critical to the acceptance of relativity.
7.1 Description of the Eddington Experiment:
One of the first considerations of gravitational deflection of light was published in 1801, when Johann Georg von Soldner pointed out that Newtonian gravity predicts that starlight will be deflected when it passes near a massive object. Initially, in a paper published in 1911, Einstein had incorrectly calculated that the amount of light deflection was the same as the Newtonian value. There had been plans by an American team from the Lick Observatory to measure the amount of deflection by making observations of an eclipse in Brazil in 1912, but bad weather prevented observations being made. Eddington had taken part in a British expedition to Brazil to observe the 1912 eclipse but was interested in different measurements.
Although Einstein's main work on general relativity was not published until 1915, he was aware before then that his 1911 calculation had been wrong, and that in fact the predicted effect in the Newtonian model is only half the value predicted by general relativity. This suggested a possible test for his theory, and in 1913 Einstein asked George Ellery Hale to suggest a way of detecting the deflection of light from a star as it passed the Sun.
The eclipse was due to take place in the early afternoon of 29 May, at 2pm, but that morning there was a storm with heavy rain. Eddington wrote:
The rain stopped about noon and about 1.30 ... we began to get a glimpse of the sun. We had to carry out our photographs in faith. I did not see the eclipse, being too busy changing plates, except for one glance to make sure that it had begun and another half-way through to see how much cloud there was. We took sixteen photographs. They are all good of the sun, showing a very remarkable prominence; but the cloud has interfered with the star images. The last few photographs show a few images which I hope will give us what we need ...
Eddington developed the photographs on Principe, and attempted to measure the change in the stellar positions during the eclipse. On 3 June, despite the clouds that had reduced the quality of the plates, Eddington recorded in his notebook: "... one plate I measured gave a result agreeing with Einstein."
In the post-Newtonian tests of gravity, the parameterized post-Newtonian formalism parameterizes, in terms of ten adjustable parameters, all the possible departures from Newton's law of universal gravitation. The earliest parameterizations of the post-Newtonian approximation were performed by Eddington (1922). The parameter concerned with the amount of deflection of light by a gravitational source is the so-called Eddington parameter (γ). It is the best constrained of the ten post-Newtonian parameters.
The early accuracy of eclipse measurements, however, was poor. Dyson et al. quoted an optimistically low uncertainty in their measurement, which is argued by some to have been plagued by systematic error and possibly confirmation bias, although modern reanalysis of the dataset suggests that Eddington's analysis was accurate.
In 1801 Johann Georg von Soldner had pointed out that Newtonian gravity predicts that starlight will bend around a massive object, but the predicted effect is only half the value predicted by general relativity as calculated by Einstein in his 1911 paper. The results of Soldner were revived by the Nobel laureate Philipp Lenard in an attempt to discredit Einstein. Eddington had been aware in 1919 of the alternative predictions.
Considerable uncertainty remained in these measurements for almost fifty years, until observations started being made at radio frequencies. It was not until the late 1960s that it was definitively shown that the amount of deflection was the full value predicted by general relativity, and not half that number.
The theory behind the experiment concerns the predicted deflection of light by the Sun. The first observation of light deflection was performed by noting the change in position of stars as they passed near the Sun on the celestial sphere. The approximate angular deflection δφ for a massless particle coming in from infinity and going back out to infinity is given by the following formula: [the formula is not shown here due to the next statement.]
Although this formula is approximate, it is accurate for most measurements of gravitational lensing, due to the smallness of the ratio rs/b. For light grazing the surface of the sun, the approximate angular deflection is roughly 1.75 arcseconds. This is twice the value predicted by calculations using the Newtonian theory of gravity. It was this difference in the deflection between the two theories that Eddington's expedition and other later eclipse observers would attempt to observe.
Dyson, when planning the expedition in 1916, had chosen the 1919 eclipse because it would take place with the Sun in front of a bright group of stars called the Hyades. The brightness of these stars would make it easier to measure any changes in position. [Reference:
This description of the bad weather is important, but Eddington achieved his primary goal of seeking "a result agreeing with Einstein."
This experiment should have 2 goals:
1) Confirm Einstein's prediction,
2) Verify there is no conflicting evidence.
The second goal should have been just as important as the first.
The description of the observation mentions only the one star on the solar limb, which was the primary goal for the expedition. Unfortunately for this pivotal experiment, this particular selection offers 2 distinct mechanisms for its light to bend.
1) Hypothetical bending by gravity,
2) Known behavior of bending by atmospheric refraction.
At the solar limb, the solar atmosphere is at its maximum density by gravity pulling down loose plasma particles down to the photosphere surface. Their kinetic energy maintains an uneven distribution.
On the Earth: "you can actually see the Sun a few minutes before it rises and a few minutes after it sets" This is because of [atmospheric] refraction." Many have observed this behavior, when having a clear view of the horizon. [Reference:
This refraction is why the second goal was so important. The constellation of Hyades provided stars to check. Using stars in Hyades was noted in 2016.
The cloudy conditions imply only the Sun and only the bright star on its limb might be captured in any images.
With gravitational lensing, ALL objects in the view should have been affected, but by their distance from the Sun. I recall web articles from 2019 stating other observers, not Eddington, noted several stars and even a planet somewhat behind the Sun, were not shifted as expected' rough sky maps were included. Those old articles must have been purged from the web over time, and could not be found today, 2 years later.
When browsing for subsequent tests of stars not at the solar limb, no such tests are found. Apparently, these tests seek to repeat the original check of a prediction only at the limb.
Refraction surely occurs at the limb. If that is the only star being checked, then refraction by the solar atmosphere or corona has been confirmed numerous times.
Until all stars around the Sun are verified to match a prediction for each object's distance, this experiment cannot be considered thorough.
Gravitational lensing is not confirmed by this single experiment.
The force of gravity does not interact with the propagation of electric and magnetic fields. Gravity is a force limited to only particles having mass.
The story about Einstein's prediction has a relevant reference in the story of Johann Georg von Soldner.
Soldner is now mostly remembered for having concluded — based on Newton's corpuscular theory of light — that light would be diverted by heavenly bodies. In a paper written in 1801 and published in 1804, he calculated the amount of deflection of a light ray by a star [...], one finds ω=0,84"".
Albert Einstein calculated and published a value for the amount of gravitational light-bending in light skimming the Sun in 1911, leading Phillipp Lenard to accuse Einstein of plagiarising Soldner's result. [Reference:
So much emphasis has been made of comparing Einstein's prediction to that predicted by Newton's gravity.
When looking at the history of these two supposed predictions, it is unclear how valid either prediction is, when comparing the origin and value of each.
7.2 Edward Dowdye
Dr. Edward Dowdye is a scientist who measured and explained how star light can be bent when passing through the solar corona.
He demonstrates the angle is predictable based on where it enters the cor
ona. This proves that gravity or space-time are not the correct mechanism for the observations of the Eddington Experiment in 1919.
He explained his work with the solar corona bending the light passing through its matter, in this YouTube video: [Reference:
Stars BEND LIGHT? General Relativity and Gravity with Dr. Edward Dowdye!
His site has another useful article.
Why are the Einstein Rings not seen in the star-filled skies?
Dowdye's web site has another useful article.
Why are the Einstein Rings not seen in the star-filled skies?
Gravitational light bending, as predicted by General Relativity, should be easily noticeable at multiple solar radii well into the empty vacuum space above the solar plasma rim.
Remarkably as it may seem, however, historically the solar light bending effect has been observed only at the solar rim, the refractive plasma atmosphere of the sun. This is strongly confirmed by a large number of very-long-baseline-interferometer (VLBI) measurements on the gravitational deflection of microwaves from radio pulsar sources that were deflected at the thin plasma rim of the sun at precisely the angle of 1.75 arcsec. [Reference:
This web page includes an animation of the observed angles of deflection. Refraction occurs only when the light path is through the corona. Relativity predicts a deflection which varies proportionally by distance from the solar limb. Therefore, relativity fails at all other observed paths, or when not at the solar limb.
This page has this chart with Dowdye's test results:
Here is the important image with the results. from the linked page.
The only successful prediction by relativity about light bending is only a star on the solar limb, with the maximum refraction in the solar corona.
Microlensing explains the claimed illusion with magnified distant objects. A gravitational lens is invoked for this claimed magnification. Here is its definition.
Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit much light (stars) or large objects that block background light (clouds of gas and dust). These objects make up only a minor portion of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light. [Reference:
This behavior of brightening in space is impossible, because it violates the conservation of energy. A magnification is an increase in intensity of the light or an increase in the energy of the propagating wavelengths.
To increase the energy in the wavelengths there must be a defined external source transferring energy to the light. Microlensing never identifies the required external energy source. There is no mechanism for the lens object to somehow transfer any energy to the light passing at a distance.
Therefore, whenever this microlensing is invoked, the observed object must be treated just as observed.
Dr. Dowdye published a paper titled
Important Fundamentals of Mathematical Physics Have Been Found to be Misapplied to Concepts of Gravitational Lensing
Pure classical research in the area of an emission theory predicts there can be absolutely no direct interaction between gravitation and electromagnetism. Convincing astrophysical evidence supports this theory. [Reference:
7.5 summary of this section
Dr. Edward Dowdye provides the correct explanation, with evidence, of the observations by Eddington in 1919.
The path of light Light cannot bend by gravity or space-time. Light bends only by refraction in the medium.
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last change 01/25/2022