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Space Time and Gravitation - An Outline of The General Relativity Theory
By his theory of relativity Albert Einstein has provoked a revolution of thought in physical science.
The achievement consists essentially in this:|Einstein has succeeded in separating far more completely than hitherto the share of the observer and the share of external nature in the things we see happen. The perception of an object by an observer depends on his own situation and circumstances; for example, distance will make it appear smaller and dimmer.
We make allowance for this almost unconsciously in interpreting what we see. But it now appears that the allowance made for the motion of the observer has hitherto been too crude a fact overlooked because in practice all observers share nearly the same motion, that of the earth.
Physical space and time are found to be closely bound up with this motion of the observer; and only an amorphous combination of the two is left inherent in the external world. When space and time are relegated to their proper source the observer the world of nature which remains appears strangely unfamiliar; but it is in reality simplified, and the underlying unity of the principal phenomena is now clearly revealed. The deductions from this new outlook have, with one doubtful exception, been confirmed when tested by experiment.
It is my aim to give an account of this work without introducing anything very technical in the way of mathematics, physics, or philosophy. The new view of space and time, so opposed to our habits of thought, must in any case demand unusual mental exercise. The results appear strange; and the incongruity is not without a humorous side. For the first nine chapters the task is one of interpreting a clear-cut theory, accepted in all its essentials by a large and growing school of physicists although perhaps not everyone would accept the author's views of its meaning.
Chapters x and xi deal with very recent advances, with regard to which opinion is more fluid. As for the last chapter, containing the author's speculations on the meaning of nature, since it touches on the rudiments of a philosophical system, it is perhaps too sanguine to hope that it can ever be other than controversial.
A non-mathematical presentation has necessary limitations; and the reader who wishes to learn how certain exact results follow from Einstein's, or even Newton's, law of gravitation is bound to seek the reasons in a mathematical treatise. But this limitation of range is perhaps less serious than the limitation of intrinsic truth. There is a relativity of truth, as there is a relativity of space.
“For is and is-not though with Rule and Line and up-and-down without, I could define."
Alas! It is not so simple. We abstract from the phenomena that which is peculiar to the position and motion of the observer; but can we abstract that which is peculiar to the limited imagination of the human brain?
We think we can, but only in the symbolism of mathematics. As the language of a poet rings with a truth that eludes the clumsy explanations of his commentators, so the geometry of relativity in its perfect harmony expresses a truth of form and type in nature, which my bowdlerized version misses.
But the mind is not content to leave scientific Truth in a dry husk of mathematical symbols, and demands that it shall be alloyed with familiar images. The mathematician, who handles x so lightly, may fairly be asked to state, not indeed the inscrutable meaning of x in nature, but the meaning which x conveys to him. Although primarily designed for readers without technical knowledge of the subject, it is hoped that the book may also appeal to those who have gone into the subject more deeply.
The achievement consists essentially in this:|Einstein has succeeded in separating far more completely than hitherto the share of the observer and the share of external nature in the things we see happen. The perception of an object by an observer depends on his own situation and circumstances; for example, distance will make it appear smaller and dimmer.
We make allowance for this almost unconsciously in interpreting what we see. But it now appears that the allowance made for the motion of the observer has hitherto been too crude a fact overlooked because in practice all observers share nearly the same motion, that of the earth.
Physical space and time are found to be closely bound up with this motion of the observer; and only an amorphous combination of the two is left inherent in the external world. When space and time are relegated to their proper source the observer the world of nature which remains appears strangely unfamiliar; but it is in reality simplified, and the underlying unity of the principal phenomena is now clearly revealed. The deductions from this new outlook have, with one doubtful exception, been confirmed when tested by experiment.
It is my aim to give an account of this work without introducing anything very technical in the way of mathematics, physics, or philosophy. The new view of space and time, so opposed to our habits of thought, must in any case demand unusual mental exercise. The results appear strange; and the incongruity is not without a humorous side. For the first nine chapters the task is one of interpreting a clear-cut theory, accepted in all its essentials by a large and growing school of physicists although perhaps not everyone would accept the author's views of its meaning.
Chapters x and xi deal with very recent advances, with regard to which opinion is more fluid. As for the last chapter, containing the author's speculations on the meaning of nature, since it touches on the rudiments of a philosophical system, it is perhaps too sanguine to hope that it can ever be other than controversial.
A non-mathematical presentation has necessary limitations; and the reader who wishes to learn how certain exact results follow from Einstein's, or even Newton's, law of gravitation is bound to seek the reasons in a mathematical treatise. But this limitation of range is perhaps less serious than the limitation of intrinsic truth. There is a relativity of truth, as there is a relativity of space.
“For is and is-not though with Rule and Line and up-and-down without, I could define."
Alas! It is not so simple. We abstract from the phenomena that which is peculiar to the position and motion of the observer; but can we abstract that which is peculiar to the limited imagination of the human brain?
We think we can, but only in the symbolism of mathematics. As the language of a poet rings with a truth that eludes the clumsy explanations of his commentators, so the geometry of relativity in its perfect harmony expresses a truth of form and type in nature, which my bowdlerized version misses.
But the mind is not content to leave scientific Truth in a dry husk of mathematical symbols, and demands that it shall be alloyed with familiar images. The mathematician, who handles x so lightly, may fairly be asked to state, not indeed the inscrutable meaning of x in nature, but the meaning which x conveys to him. Although primarily designed for readers without technical knowledge of the subject, it is hoped that the book may also appeal to those who have gone into the subject more deeply.
210 pages, Kindle Edition
First published January 3, 1920
25 people are currently reading
295 people want to read
About the author
Arthur Stanley Eddington
56 books55 followersSir Arthur Stanley Eddington, OM, FRS was a British astrophysicist of the early 20th century. The Eddington limit, the natural limit to the luminosity of stars, or the radiation generated by accretion onto a compact object, is named in his honour.
He is famous for his work regarding the Theory of Relativity. Eddington wrote a number of articles which announced and explained Einstein's theory of general relativity to the English-speaking world. World War I severed many lines of scientific communication and new developments in German science were not well known in England. He also conducted an expedition to observe the Solar eclipse of May 29, 1919 that provided one of the earliest confirmations of relativity, and he became known for his popular expositions and interpretations of the theory.
He is famous for his work regarding the Theory of Relativity. Eddington wrote a number of articles which announced and explained Einstein's theory of general relativity to the English-speaking world. World War I severed many lines of scientific communication and new developments in German science were not well known in England. He also conducted an expedition to observe the Solar eclipse of May 29, 1919 that provided one of the earliest confirmations of relativity, and he became known for his popular expositions and interpretations of the theory.
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Displaying 1 - 6 of 6 reviews
August 27, 2023
The complex concepts in the book (the book’s title) are not, as conveyed by Eddington, easy to understand. I’d say that the book has four overarching themes:
First, everything in the cosmos exists in a field of movement and, therefore, everything is in motion relative to everything else. For physics, which is measurement of intervals between two or more events (points), this is relativity. There is no privileged point (inertial frame) to measure something. Rather, any reference point must be stipulated: “the gravitational field…is not absolute, but always requires that some observer should be specified.” Since everything is in motion relative to each other, any (reference to) reference point, given the vastness of the cosmos, also must be specified in four dimensions: “right-and-left, backwards-and-forwards, up-and-down, sooner-and-later”).
Second, at all cosmological scales (and quantum scales too?), everything exists in a curvature. Mass that is bound energy (congealed energy “which is not yet releasable” or, rest mass as potential energy and motion as expressed energy), curves the fabric of spacetime, creating movement toward itself (subject to the inverse square law: relative size and distance of massive bodies to each other). The drawing of mass-energy together in turn creates greater mass and curvature. This appears to be a predating of Wheeler’s “spacetime tells matter how to move; matter tells spacetime how to curve.”
Third, as the cosmos is curved, mass-energy’s natural straight-line, inertial track, moves around, and turns back to itself. Spacetime, Eddington states, may have “an essential curvature at a great scale,” something he refers to as “the sphericity of the world.” In illustrating this point, Eddington refers to a ray from our sun that, in zillions of years, returns to itself, to a “ghostly” point in space as the sun either no longer exists or because it has moved position. Thus, Eddington says, physics has moved from “a mechanical to a geometric theory of fields of force.”*
Regarding this issue of overall curvature, Eddington states that centrifugal force (outward movement) increases until it reaches the sphere of greatest area and then per gravitation, diminishes to zero in the antipodes. It is not clear if Eddington is writing literally of a centrifugal force as if a rotating singularity pulls in and pushes out mass-energy, or if a big bang sends released mass-energy outward until, per the inverse square law, it reaches its antipode condition (stasis) when, released from gravity, inertial movement continues around, back toward a cosmic starting point, driven by the geometric theory of curvature by an overall, cosmic gravitational center.
Fourth, Eddington’s last chapter, “On the Nature of Things,” per Lucretius I presume, puts his physics into a philosophical framework, though not in a particularly clear way. The world is not governed by stasis. It is governed by movement: Natural, inertial, movement under the presence of curvature. Curvature moves, and movement toward the center creates curvature. There is no absolute beginning. There is no super prime mover agent that got all things rolling. Everything moves between the two antipodal differentials. The mind thinks in terms of linear cause and effect, with absolute points anchoring it all, but that is an illusion,** really, though not the kind of illusion that Plato wrote about in his cave analogy. Yet, in the end, Eddington gets a bit too mystical for me in his theory of “mind-stuff” in which the laws of reality lie in the mind because, it seems to me, the cosmos just is, and the mind encapsulates what is through the formation of laws.*** That’s my best attempt to make sense of what he’s saying here.
This notion of movement back and forth in some great cosmic rhythm without beginning or end is a tough one to grasp.**** We’re about survival. Survival is about, relatively, permanent things (needs and threats) related to survival (Quoting a person named Lodge, Eddington writes “'...our senses were developed by the struggle for existence, not for the purpose of philosophizing the world'”), and their linear cause-effect relationships. Perpetual, causeless, movement means that the cosmos always was. There never was a beginning; there never will be an end.
*The natural track of (inertial) motion is a straight-line - the principle of movement is the the principle of least effort. But in the presence of an all-pervading curvature, straight-line movement’s natural track (though Eddington qualifies it by saying that light is deflected by local gravitation or absorbed by matter) is to curve (be accelerated by large mass-energy bodies) and eventually, to return to itself. Movement through a large gravitational field follows the principle of least action: the shortest length and least time is curved, not straight-line, movement. Also, because straight-line motion is always under curvature, there is rotation, a movement around. “Geodesic structures,” (gravitational centers), he says, “rules all matter.” Eddington writes that the distinction between force as a cause and inertia that is natural movement without a cause “cannot be sustained.” Movement flows from high to low, from low to high, a natural and internal dynamic between states of imbalance and balance. There is nothing that reaches out, grabs and pulls. More specifically, reality is relations. It is a field of movement between the antipodes.
** “Mind,” Eddington writes, “exalts the permanent and ignores the transitory.”
***Nature just is, “but the whole of those laws of nature which have been woven into a unified scheme - mechanics, gravitation, electrodynamics and optics - have their origin, not in any special mechanism of nature, but in the workings of the mind. ‘Give me matter and motion,’ said Descartes, ‘and I will construct the universe.’ The mind reverses this. ‘Give me a world - a world in which there are relations - and I will construct matter and motion.’ Are there then no genuine laws in the external world? Laws inherent in the substratum of events, which break through into the phenomena otherwise regulated by the despotism of the mind? We cannot foretell what the final answer will be; but, at present, we have to admit that there are laws which appear to have their seat in external nature. The most important of these if not the only law, is a law of atomicity…..Action is generally regarded as the most fundamental thing in the real world of physics, although the mind passes it over because of its lack of permanence; and it is vaguely believed that the atomicity of action is the general law, and the appearance of electrons is in some way dependent on this….We have found a strange foot-print on the shores of the unknown. We have devised profound theories, one after another, to account for its origin. At last, we have succeeded in reconstructing the creature that made the foot-print. And, lo, it is our own.”
****Hubble findings, as confirmed, arguably, by others, of an expanding cosmos, at an ever increasing speed, counters this back and forth rhythmic structure. On this point, Eddington seems (I don't really understand it) to offer the possibility of another explanation for that Hubble finding: "The data are not so ample as we should like; but there is no doubt that large receding motions greatly preponderate. This may be a genuine phenomenon in the evolution of the material universe; but it is also possible that the interpretation of spectral displacement as a receding velocity is erroneous; and the effect is really the slowing of atomic vibrations predicted by de Sitter's theory." Given Eddington's leanings to "mind-stuff," his reference to "the material universe" is interesting.
First, everything in the cosmos exists in a field of movement and, therefore, everything is in motion relative to everything else. For physics, which is measurement of intervals between two or more events (points), this is relativity. There is no privileged point (inertial frame) to measure something. Rather, any reference point must be stipulated: “the gravitational field…is not absolute, but always requires that some observer should be specified.” Since everything is in motion relative to each other, any (reference to) reference point, given the vastness of the cosmos, also must be specified in four dimensions: “right-and-left, backwards-and-forwards, up-and-down, sooner-and-later”).
Second, at all cosmological scales (and quantum scales too?), everything exists in a curvature. Mass that is bound energy (congealed energy “which is not yet releasable” or, rest mass as potential energy and motion as expressed energy), curves the fabric of spacetime, creating movement toward itself (subject to the inverse square law: relative size and distance of massive bodies to each other). The drawing of mass-energy together in turn creates greater mass and curvature. This appears to be a predating of Wheeler’s “spacetime tells matter how to move; matter tells spacetime how to curve.”
Third, as the cosmos is curved, mass-energy’s natural straight-line, inertial track, moves around, and turns back to itself. Spacetime, Eddington states, may have “an essential curvature at a great scale,” something he refers to as “the sphericity of the world.” In illustrating this point, Eddington refers to a ray from our sun that, in zillions of years, returns to itself, to a “ghostly” point in space as the sun either no longer exists or because it has moved position. Thus, Eddington says, physics has moved from “a mechanical to a geometric theory of fields of force.”*
Regarding this issue of overall curvature, Eddington states that centrifugal force (outward movement) increases until it reaches the sphere of greatest area and then per gravitation, diminishes to zero in the antipodes. It is not clear if Eddington is writing literally of a centrifugal force as if a rotating singularity pulls in and pushes out mass-energy, or if a big bang sends released mass-energy outward until, per the inverse square law, it reaches its antipode condition (stasis) when, released from gravity, inertial movement continues around, back toward a cosmic starting point, driven by the geometric theory of curvature by an overall, cosmic gravitational center.
Fourth, Eddington’s last chapter, “On the Nature of Things,” per Lucretius I presume, puts his physics into a philosophical framework, though not in a particularly clear way. The world is not governed by stasis. It is governed by movement: Natural, inertial, movement under the presence of curvature. Curvature moves, and movement toward the center creates curvature. There is no absolute beginning. There is no super prime mover agent that got all things rolling. Everything moves between the two antipodal differentials. The mind thinks in terms of linear cause and effect, with absolute points anchoring it all, but that is an illusion,** really, though not the kind of illusion that Plato wrote about in his cave analogy. Yet, in the end, Eddington gets a bit too mystical for me in his theory of “mind-stuff” in which the laws of reality lie in the mind because, it seems to me, the cosmos just is, and the mind encapsulates what is through the formation of laws.*** That’s my best attempt to make sense of what he’s saying here.
This notion of movement back and forth in some great cosmic rhythm without beginning or end is a tough one to grasp.**** We’re about survival. Survival is about, relatively, permanent things (needs and threats) related to survival (Quoting a person named Lodge, Eddington writes “'...our senses were developed by the struggle for existence, not for the purpose of philosophizing the world'”), and their linear cause-effect relationships. Perpetual, causeless, movement means that the cosmos always was. There never was a beginning; there never will be an end.
*The natural track of (inertial) motion is a straight-line - the principle of movement is the the principle of least effort. But in the presence of an all-pervading curvature, straight-line movement’s natural track (though Eddington qualifies it by saying that light is deflected by local gravitation or absorbed by matter) is to curve (be accelerated by large mass-energy bodies) and eventually, to return to itself. Movement through a large gravitational field follows the principle of least action: the shortest length and least time is curved, not straight-line, movement. Also, because straight-line motion is always under curvature, there is rotation, a movement around. “Geodesic structures,” (gravitational centers), he says, “rules all matter.” Eddington writes that the distinction between force as a cause and inertia that is natural movement without a cause “cannot be sustained.” Movement flows from high to low, from low to high, a natural and internal dynamic between states of imbalance and balance. There is nothing that reaches out, grabs and pulls. More specifically, reality is relations. It is a field of movement between the antipodes.
** “Mind,” Eddington writes, “exalts the permanent and ignores the transitory.”
***Nature just is, “but the whole of those laws of nature which have been woven into a unified scheme - mechanics, gravitation, electrodynamics and optics - have their origin, not in any special mechanism of nature, but in the workings of the mind. ‘Give me matter and motion,’ said Descartes, ‘and I will construct the universe.’ The mind reverses this. ‘Give me a world - a world in which there are relations - and I will construct matter and motion.’ Are there then no genuine laws in the external world? Laws inherent in the substratum of events, which break through into the phenomena otherwise regulated by the despotism of the mind? We cannot foretell what the final answer will be; but, at present, we have to admit that there are laws which appear to have their seat in external nature. The most important of these if not the only law, is a law of atomicity…..Action is generally regarded as the most fundamental thing in the real world of physics, although the mind passes it over because of its lack of permanence; and it is vaguely believed that the atomicity of action is the general law, and the appearance of electrons is in some way dependent on this….We have found a strange foot-print on the shores of the unknown. We have devised profound theories, one after another, to account for its origin. At last, we have succeeded in reconstructing the creature that made the foot-print. And, lo, it is our own.”
****Hubble findings, as confirmed, arguably, by others, of an expanding cosmos, at an ever increasing speed, counters this back and forth rhythmic structure. On this point, Eddington seems (I don't really understand it) to offer the possibility of another explanation for that Hubble finding: "The data are not so ample as we should like; but there is no doubt that large receding motions greatly preponderate. This may be a genuine phenomenon in the evolution of the material universe; but it is also possible that the interpretation of spectral displacement as a receding velocity is erroneous; and the effect is really the slowing of atomic vibrations predicted by de Sitter's theory." Given Eddington's leanings to "mind-stuff," his reference to "the material universe" is interesting.
December 17, 2017
To be honest I did not understand most parts of this book when I read it, since it has references to Tensor Calculus, which as a student of 11th standard, I could not grasp (though I was familiar with the basics of calculus). However, I did understand the concepts of general relativity from this book. It also outlines Eddington's account of his famous experiment that established General Relativity firmly.
September 18, 2023
better than I expected.
Eddington was a pretty good writer so this wasn’t too hard to follow. The subject is complicated, so you really have to concentrate and you may find yourself re reading sections. Still, it’s worthwhile hearing from the people who made the discoveries.
Eddington was a pretty good writer so this wasn’t too hard to follow. The subject is complicated, so you really have to concentrate and you may find yourself re reading sections. Still, it’s worthwhile hearing from the people who made the discoveries.
February 10, 2021
The book about the birth of many fields of Physics.
December 29, 2024
An interesting read. I’ll have to go over it many times before I can gain any understanding. One thing I did learn is that “flat earth-ers” have a “homaloidal” view of the earth.
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August 27, 2016At last, I found the way to how to make a perfect round-trip time machine! Neither the corpuscular theory nor the wave theory, I'm sure!! ......
Displaying 1 - 6 of 6 reviews