What do you think?
Rate this book
Space, Time and Einstein
An enlightening introduction to the philosophy of time and space. J.B. Kennedy offers an introduction to one of the liveliest and most popular fields in philosophy - time and space - aimed specifically at a beginning readership with no background in philosophy or science. He goes to the philosophical heart of the issues without recourse to jargon, mathematics, or logical formulas and introduces Einstein's revolutionary ideas in a clear and simple way, as well as concepts and arguments of other relevant philosophers, both ancient and modern. Current debates in philosophy and physics are also handled with exemplary clarity and Kennedy is able to provide readers with a real sense of where we have come from and where we are going. The writing is engaging, lively, and entertaining and serves to introduce the subject to beginning students as well as providing a clear statement of the "state of the debate" for a popular science readership. Kennedy covers such topics as Einstein's special and general relativity, how to build an atom bomb, the four-dimensional universe, the possibility of time travel, the impossibility of motion, whether space curves, the big bang, black holes, and the idea of inflationary and accelerating universes.
- GenresSciencePhysicsNonfiction
192 pages, Paperback
First published January 31, 2003
6 people are currently reading
70 people want to read
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
Displaying 1 - 4 of 4 reviews
March 5, 2017
The book is about philosophical implications of various ideas about space and time. The author has presented the ideas as old as those of Greeks and up to present. The language is very simple and discussion is meant for beginners. I loved the book specially the part on Newton and Leibniz.
July 30, 2016
1)
- Metaphyics: the study of reality
- Epistemology: the study of knowledge
- Ethics: the study of good and evil, of values
A later editor bound the Aristotle's books together into volumes and gave each volume a title. One dealt with "Physics", and was so entitled. The next dealt with more basic questions but had no title. It came to be called 'the book that came after the one entitled Physics', and this name 'After-the-Phyics' or 'Metaphysics'('meta' means 'after' in Greek) has stuck through ages.
2) Hendrik Lorentz had a major role in discovery of the electron, for which he received one of the first Nobel prizes in 1902. Einstein seems to have idolized Lorentz, he once wrote "I admire this man as no other, I would say I love him". Decades later, before his own death he said to one of his colleague "He meant more to me personally, than anyone else I have met in my lifetime"
2)
The Mainstream Interpretation of SR
Albert Einstein is the founding father of what is called 'the minority interpretation'. It says distances and durations(and other relative properties) are not real properties.
1. If a property is not invariant, then it is not real. (Promise)
2. Distances and durations are not invariant. (Promise)
3. Therefore, distances and durations are not real properties. (Result from 1, 2)
Note: Energy and momentum and other things are not also invariant
Promise 1. is not a part of SR but the interpretation of SR. However, Promise 2. is so.
Although they are not real properties, they are real relations, not just a mere appearance.
The Minority Interpretation of SR
Hendrik Lorentz is the founding father of what is called 'the minority interpretation'. It says distances and durations are real and variable with speed. Therefore, it will break the democracy between reference frames. If some events are stationary from the perspective from ether, which is an absolute frame, then the distance and duration between events will have their real properties. In this interpretation, length contraction and time dilation are physical effects of moving in ether. It also explains why the speed of light is constant because light travels in ether, it's normal that it has same speed relative to ether.
Most of physicists deny the minority interpretation, which is the reason why it is called 'minority', because it postulates the existence of an absolute frame(ether), which has no evidence. To sum up, you will think that your shoes have no size(majority interpretation) or they have variable size(minority interpretation)
3) Suppose a car goes through a tunnel which has the same proper length with the car. From the perspective of a person in the car, the length of the tunnel is shorter than the length of car. However, from the perspective of a person standing inside the tunnel, the length of the car is the shorter one.
In major interpretation, there is no contradictory but symmetry because the length of something is a relative property.
In minor interpretation, if we suppose the tunnel is stationary from the perspective of ether, only the calculations made from the perspective of the person in the tunnel are right. Thus, the moving car is really contracted. However, the person in the car makes wrong calculations because his movement in ether.
4) Twin paradox shows an asymmetry between reference frames because of asymmetry motion of one of the twins. Therefore, inertial motions are relative, but accelerating motions are physical.
5) The minority interpretation interprets increase of mass described as the resistance of force as an effect of resistance of ether. A falling object in an environment with air is a good analogy for this phenomenon. Because the resistance of air increases with velocity of the object, the velocity of object remains at a constant velocity.
It also seems in charged particles moving through electromagnetic field. Therefore, the resistance caused by electromagnetic field is called 'electromagnetic field'.
Note: I totally disagree with the concept of 'relativistic mass', we can call it energy instead.
6) Measurement of distance depends on time and also measurement of time depends on space, I've already showed in calculations of length contraction and time dilation in Lorentz Transformation file. Shortly, try to find length contraction we say t'=0 and to find time dilation we say x'=0.
7) Distinct events that creates the illusion of persistence is called an 'enduring object' but an object moves through the time from one moment to next is called an 'persisting object'. Some may criticize endurance because our common sense agree that there is motion, however, defenders of event ontologies argue that we do not, in fact, see motion. We see an object one place and have a similar object in another place. Thus, we have an illusion of motion that doesn't exist. Therefore, event ontology is compatible with our experience and observations. Some philosophers also criticize event ontologies saying that they make the similarity of events in a sequence an incredible accident. Why should the event of the racquet striking the ball be followed by another event that includes the ball? Defenders of admits that this has no physical explanation, perhaps God decreed that events have a pleasing order. But they continue, there is also an unexplainable brute fact in objects persist through time because laws that explain motion of objects have no explanation.
8) Belief in that only the present exists is called 'presentism'. The different parts of space all coexist in a present moment, but only one part of time, present, exists. Presentism is compatible with either the existence of persistent objects moving through time or with an event ontology because itis indifferent to what the present consists of, that is, whether it is persistent objects or events.
Many interpreters of relativity have asserted that the theory proves that presentism is false. Instead, the past and future coexist with the present, and are just as real as the present, such a world is called 'the block universe'. Four-dimensional block universe would be made up of three-dimensional slices of space at instant times. If it is true that we live in a block universe, then there are no objects persisting through time. That is, a block universe implies an event ontology. This is because there is no real motion or change in a block universe. In a block universe, future events have an existence that is just as real and full-blooded as present events.
9)
- Laplacian determinism: the view that conditions at the present moment together with physical laws determine all future events. That is, laws ensure that the future can happen in only one way.
- Fatalism: the view that all future events are fixed, but not necessarily by physical laws. That is, the future can happen in only one way, but there may be no regular or law-like patterns in future events. Perhaps God or fortune has decreed that a series of miracles or physically uncaused events come about.
The block universe view is fatalistic. In a block universe, there can be only one future because it is already there, and in some sense has already happened. But the block universe view does not depend on the existence of laws, or any regularities between slices.
10) According to mainstream interpretation neither space nor time does exist but their combination does. Minkovski helped clarify the meaning of the spacetime interval with his well-known rotation analogy. Consider some three-dimensional object such as a sculpture of Venus. As we view it from different angles, its width may change. It may seem wide when viewed from the front, but seem narrow when viewed from the side. Minkovski said that spacetime is real, but that different sets of rulers and clocks are all “viewing it from different perspectives”.
The minority interpretation accepts, of course, the fact that the spacetime interval is invariant, but it interprets it as a mathematical accident. Movement through the ether causes lengths to contract and clocks to slow. Since these two processes have “opposite” effects, we should not be surprised that, if we combine both in a calculation, they cancel and leave a constant. Lorentz never thought that the invariance of the spacetime interval was important.
11) Although his views changed during his career, Einstein, for example, made the following statement in 1952, a few years before he died. He argued that the relativity of simultaneity implies a block universe:
"The four-dimensional continuum is now no longer resolvable objectively into slices, all of which contain simultaneous events, 'now' loses for the spatially extended world its objective meaning . . . Since there exist in this four-dimensional structure no longer any slices which represent 'now' objectively, the concepts of happening and becoming are indeed not completely suspended,
but yet complicated. It appears therefore more natural to think of physical reality as a four-dimensional existence, instead of, as hitherto, the evolution of a three-dimensional existence."
(Einstein, 1952)
According to him, the relativity of simultaneity seems to lead to:
"an unequivocal proof for the view of those philosophers who, like Parmenides, Kant and modern idealists (such as McTaggart), deny the objectivity of change and consider change as an illusion
or appearance. The argument runs as follows: Change becomes possible only through a lapse of time. The existence of an objective lapse of time, however, means that reality consists of an
infinity of layers of “now” which come into existence successively. But, if simultaneity is relative, reality cannot be split up into such layers in an objectively determined way. Each observer
has his own set of “nows” and none can claim the prerogative of representing the objective lapse of time."
(Gödel, 1949)
Also Bertrand Russell and Hilary Putnam have argued that relativity theory implies some kind of block universe.
12) Short argument for block universe
1. If simultaneity is relative, then there is no physical
difference between the past, present and future. (P)
2. Simultaneity is relative. (P)
3. Therefore, there is no physical difference between
the past, present and future. (from 1, 2)
4. But, if there is no physical difference between the
past, present and future, then there is no true change. (P)
5. Therefore, there is no true change. (3, 4)
The last line means that we live in a block universe.
According to presentism, change is the passing away of one slice and the emergence of the next. But if Einstein’s theory is a good map of reality, then there is no physical difference between the present slice of events and past or future slices. If there is no true change, then any event that ever existed always exists: it cannot change from existent to nonexistent. A realistic interpretation of the relativity of simultaneity is incompatible with presentism.
13) Triangle argument for block universe
1. If an event exists and it is simultaneous with another
event, then the other event also exists. (P)
2. Me-now exists; me-now and the supernova are
simultaneous. (P)
3. Therefore, the supernova exists. (from 1, 2)
4. But, the supernova and me-tomorrow are
simultaneous. (P: according to other clocks)
5. Therefore, me-tomorrow exists. (from 1,3,4)
6. If one event exists and another event exists, then
they co-exist. (P)
7. Therefore me-now and me-tomorrow co-exist. (from 2,5,6)
Clearly the first premise, A, is very suspicious. It moves from a conventional label, “simultaneous”, to an assertion about physical existence. This is precisely the inference that Einstein’s theory is
supposed to deny. But the only alternative (short of solipsism) is to concede that some events in the past and future do coexist, and the argument is aimed at those who wish to deny this.
The fourth line of the argument, premise D, has troubled some critics. It implies that two sets of clocks and rulers, and therefore two definitions of simultaneity, are used. In the context of this argument, however, this is legitimate. Briefly put, premise A says that simultaneity is good evidence for objective existence. Once we know something exists, we are free to use other definitions of simultaneity, and that subjective choice will not affect what objectively exist.
12) For those who interpret relativity, it seems that there is no middle ground between solipsism and the block universe. Indeed, one philosopher has argued that relativity theory does imply something very close to solipsism. According to Howard Stein's view, only me-now and certain past events coexist. An event in the past coexists with me-now if light from the event could reach me, that is, past events that could have causally influenced me still exist. This appears to be a very strange view. Other people do not exist now, but their past selves may exist and therefore coexist with me. Stein’s view shows that although relativity theory makes good predictions, it appears to be very difficult to spell out what it implies about the nature of reality.
13) Thus Lorentz and other defenders of the minority interpretation can naturally say that only the present is real. The minority interpretation is compatible with presentism.
- Metaphyics: the study of reality
- Epistemology: the study of knowledge
- Ethics: the study of good and evil, of values
A later editor bound the Aristotle's books together into volumes and gave each volume a title. One dealt with "Physics", and was so entitled. The next dealt with more basic questions but had no title. It came to be called 'the book that came after the one entitled Physics', and this name 'After-the-Phyics' or 'Metaphysics'('meta' means 'after' in Greek) has stuck through ages.
2) Hendrik Lorentz had a major role in discovery of the electron, for which he received one of the first Nobel prizes in 1902. Einstein seems to have idolized Lorentz, he once wrote "I admire this man as no other, I would say I love him". Decades later, before his own death he said to one of his colleague "He meant more to me personally, than anyone else I have met in my lifetime"
2)
The Mainstream Interpretation of SR
Albert Einstein is the founding father of what is called 'the minority interpretation'. It says distances and durations(and other relative properties) are not real properties.
1. If a property is not invariant, then it is not real. (Promise)
2. Distances and durations are not invariant. (Promise)
3. Therefore, distances and durations are not real properties. (Result from 1, 2)
Note: Energy and momentum and other things are not also invariant
Promise 1. is not a part of SR but the interpretation of SR. However, Promise 2. is so.
Although they are not real properties, they are real relations, not just a mere appearance.
The Minority Interpretation of SR
Hendrik Lorentz is the founding father of what is called 'the minority interpretation'. It says distances and durations are real and variable with speed. Therefore, it will break the democracy between reference frames. If some events are stationary from the perspective from ether, which is an absolute frame, then the distance and duration between events will have their real properties. In this interpretation, length contraction and time dilation are physical effects of moving in ether. It also explains why the speed of light is constant because light travels in ether, it's normal that it has same speed relative to ether.
Most of physicists deny the minority interpretation, which is the reason why it is called 'minority', because it postulates the existence of an absolute frame(ether), which has no evidence. To sum up, you will think that your shoes have no size(majority interpretation) or they have variable size(minority interpretation)
3) Suppose a car goes through a tunnel which has the same proper length with the car. From the perspective of a person in the car, the length of the tunnel is shorter than the length of car. However, from the perspective of a person standing inside the tunnel, the length of the car is the shorter one.
In major interpretation, there is no contradictory but symmetry because the length of something is a relative property.
In minor interpretation, if we suppose the tunnel is stationary from the perspective of ether, only the calculations made from the perspective of the person in the tunnel are right. Thus, the moving car is really contracted. However, the person in the car makes wrong calculations because his movement in ether.
4) Twin paradox shows an asymmetry between reference frames because of asymmetry motion of one of the twins. Therefore, inertial motions are relative, but accelerating motions are physical.
5) The minority interpretation interprets increase of mass described as the resistance of force as an effect of resistance of ether. A falling object in an environment with air is a good analogy for this phenomenon. Because the resistance of air increases with velocity of the object, the velocity of object remains at a constant velocity.
It also seems in charged particles moving through electromagnetic field. Therefore, the resistance caused by electromagnetic field is called 'electromagnetic field'.
Note: I totally disagree with the concept of 'relativistic mass', we can call it energy instead.
6) Measurement of distance depends on time and also measurement of time depends on space, I've already showed in calculations of length contraction and time dilation in Lorentz Transformation file. Shortly, try to find length contraction we say t'=0 and to find time dilation we say x'=0.
7) Distinct events that creates the illusion of persistence is called an 'enduring object' but an object moves through the time from one moment to next is called an 'persisting object'. Some may criticize endurance because our common sense agree that there is motion, however, defenders of event ontologies argue that we do not, in fact, see motion. We see an object one place and have a similar object in another place. Thus, we have an illusion of motion that doesn't exist. Therefore, event ontology is compatible with our experience and observations. Some philosophers also criticize event ontologies saying that they make the similarity of events in a sequence an incredible accident. Why should the event of the racquet striking the ball be followed by another event that includes the ball? Defenders of admits that this has no physical explanation, perhaps God decreed that events have a pleasing order. But they continue, there is also an unexplainable brute fact in objects persist through time because laws that explain motion of objects have no explanation.
8) Belief in that only the present exists is called 'presentism'. The different parts of space all coexist in a present moment, but only one part of time, present, exists. Presentism is compatible with either the existence of persistent objects moving through time or with an event ontology because itis indifferent to what the present consists of, that is, whether it is persistent objects or events.
Many interpreters of relativity have asserted that the theory proves that presentism is false. Instead, the past and future coexist with the present, and are just as real as the present, such a world is called 'the block universe'. Four-dimensional block universe would be made up of three-dimensional slices of space at instant times. If it is true that we live in a block universe, then there are no objects persisting through time. That is, a block universe implies an event ontology. This is because there is no real motion or change in a block universe. In a block universe, future events have an existence that is just as real and full-blooded as present events.
9)
- Laplacian determinism: the view that conditions at the present moment together with physical laws determine all future events. That is, laws ensure that the future can happen in only one way.
- Fatalism: the view that all future events are fixed, but not necessarily by physical laws. That is, the future can happen in only one way, but there may be no regular or law-like patterns in future events. Perhaps God or fortune has decreed that a series of miracles or physically uncaused events come about.
The block universe view is fatalistic. In a block universe, there can be only one future because it is already there, and in some sense has already happened. But the block universe view does not depend on the existence of laws, or any regularities between slices.
10) According to mainstream interpretation neither space nor time does exist but their combination does. Minkovski helped clarify the meaning of the spacetime interval with his well-known rotation analogy. Consider some three-dimensional object such as a sculpture of Venus. As we view it from different angles, its width may change. It may seem wide when viewed from the front, but seem narrow when viewed from the side. Minkovski said that spacetime is real, but that different sets of rulers and clocks are all “viewing it from different perspectives”.
The minority interpretation accepts, of course, the fact that the spacetime interval is invariant, but it interprets it as a mathematical accident. Movement through the ether causes lengths to contract and clocks to slow. Since these two processes have “opposite” effects, we should not be surprised that, if we combine both in a calculation, they cancel and leave a constant. Lorentz never thought that the invariance of the spacetime interval was important.
11) Although his views changed during his career, Einstein, for example, made the following statement in 1952, a few years before he died. He argued that the relativity of simultaneity implies a block universe:
"The four-dimensional continuum is now no longer resolvable objectively into slices, all of which contain simultaneous events, 'now' loses for the spatially extended world its objective meaning . . . Since there exist in this four-dimensional structure no longer any slices which represent 'now' objectively, the concepts of happening and becoming are indeed not completely suspended,
but yet complicated. It appears therefore more natural to think of physical reality as a four-dimensional existence, instead of, as hitherto, the evolution of a three-dimensional existence."
(Einstein, 1952)
According to him, the relativity of simultaneity seems to lead to:
"an unequivocal proof for the view of those philosophers who, like Parmenides, Kant and modern idealists (such as McTaggart), deny the objectivity of change and consider change as an illusion
or appearance. The argument runs as follows: Change becomes possible only through a lapse of time. The existence of an objective lapse of time, however, means that reality consists of an
infinity of layers of “now” which come into existence successively. But, if simultaneity is relative, reality cannot be split up into such layers in an objectively determined way. Each observer
has his own set of “nows” and none can claim the prerogative of representing the objective lapse of time."
(Gödel, 1949)
Also Bertrand Russell and Hilary Putnam have argued that relativity theory implies some kind of block universe.
12) Short argument for block universe
1. If simultaneity is relative, then there is no physical
difference between the past, present and future. (P)
2. Simultaneity is relative. (P)
3. Therefore, there is no physical difference between
the past, present and future. (from 1, 2)
4. But, if there is no physical difference between the
past, present and future, then there is no true change. (P)
5. Therefore, there is no true change. (3, 4)
The last line means that we live in a block universe.
According to presentism, change is the passing away of one slice and the emergence of the next. But if Einstein’s theory is a good map of reality, then there is no physical difference between the present slice of events and past or future slices. If there is no true change, then any event that ever existed always exists: it cannot change from existent to nonexistent. A realistic interpretation of the relativity of simultaneity is incompatible with presentism.
13) Triangle argument for block universe
1. If an event exists and it is simultaneous with another
event, then the other event also exists. (P)
2. Me-now exists; me-now and the supernova are
simultaneous. (P)
3. Therefore, the supernova exists. (from 1, 2)
4. But, the supernova and me-tomorrow are
simultaneous. (P: according to other clocks)
5. Therefore, me-tomorrow exists. (from 1,3,4)
6. If one event exists and another event exists, then
they co-exist. (P)
7. Therefore me-now and me-tomorrow co-exist. (from 2,5,6)
Clearly the first premise, A, is very suspicious. It moves from a conventional label, “simultaneous”, to an assertion about physical existence. This is precisely the inference that Einstein’s theory is
supposed to deny. But the only alternative (short of solipsism) is to concede that some events in the past and future do coexist, and the argument is aimed at those who wish to deny this.
The fourth line of the argument, premise D, has troubled some critics. It implies that two sets of clocks and rulers, and therefore two definitions of simultaneity, are used. In the context of this argument, however, this is legitimate. Briefly put, premise A says that simultaneity is good evidence for objective existence. Once we know something exists, we are free to use other definitions of simultaneity, and that subjective choice will not affect what objectively exist.
12) For those who interpret relativity, it seems that there is no middle ground between solipsism and the block universe. Indeed, one philosopher has argued that relativity theory does imply something very close to solipsism. According to Howard Stein's view, only me-now and certain past events coexist. An event in the past coexists with me-now if light from the event could reach me, that is, past events that could have causally influenced me still exist. This appears to be a very strange view. Other people do not exist now, but their past selves may exist and therefore coexist with me. Stein’s view shows that although relativity theory makes good predictions, it appears to be very difficult to spell out what it implies about the nature of reality.
13) Thus Lorentz and other defenders of the minority interpretation can naturally say that only the present is real. The minority interpretation is compatible with presentism.
This entire review has been hidden because of spoilers.
January 7, 2019
Very lucid treatment of complex scientific theories and its philosophical implications
February 10, 2016
A delightful introduction to space and time for those of you interested more in the philosophy rather than mathematics of space and time. The author discusses problems of change, motion, infinity and shape starting with philosophers of ancient Greece to Newton and Einstein. All arguments are presented without using physics or mathematical jargon, using very straightforward logic formalism, making it accessible to any reader. On unreality of motion: “The calculus did not solve, but rather suppressed, Zeno’s paradoxes.” On black holes: “Black holes exist and give rise to infinities, which suggests that general relativity is not an ultimate theory.” On the spooky action at a distance: “in this debate, “influence” is used as (what philosophers call) a “weasel word”, that is, a vague word with a slippery meaning used to conceal ignorance. No one really knows what it is that might be travelling faster than light. It is not a cause that can be used to send signals and carries no mass or energy but is apparently not nothing, and so it an “influence” of some sort or another.”
Displaying 1 - 4 of 4 reviews