The basic principle, which turned all previous estimates, the principle of relativity, which is the physical principle of relativity of all uniform motion. Analyze how they work and again carefully.
(a) The car is in motion relative to the embankment, (b) The embankment is in motion relative to the car.
In (a) the slope (b) transport, the body serves as a benchmark rather than a statement of our movement. If it’s just a matter of discovering and describing the motion involved is basically unrelated to this criterion, we refer to the movement. As already mentioned, obviously, but it should explain more fully that the principle of relativity, we base our investigations are confused.
then the general laws of nature () such that the laws of mechanics or the law of propagation of light in vacuum is exactly the same form in both cases. This can also be expressed as follows: For the physical characteristics of natural phenomena, both the institutions and bodies K, K1 is unique (literally, especially outside) slower than others. Unlike the first, that statement does not consider the need to advance, not one of the concepts of movement and Reference-body and obtained from them, only experience can opt for the accuracy or inaccuracy.
To date, we can by no means the equality of the operators of reference K in connection with the administration of the formulation of laws of nature. Our course is more on the following lines. First, we assume that there is a reference body K whose state of motion as Galileo’s law in this regard: A matter itself, but far from all other particles moving uniformly straight. Referring K (Galilean reference-body) the laws of nature were as simple as possible. But in addition, all institutions of reference K K1 be given to this direction and should be just K for the formulation of laws of nature equal, if not in a state of uniform linear motion and rotation of K in relation to all these positions be considered as the benchmark reference of Galilee.
The validity of the principle of relativity was assumed that the bodies of reference), but not for others (for example, the possession of other traffic.
In this sense we speak of the theory of relativity or special relativity.
However, we understand the principle of general relativity, the following statement: All bodies of reference K, K1, etc., to be responsible for the equivalent description of natural phenomena (formulation of general laws), the nature, which may state movement. But before we proceed, it should be noted that the wording should be replaced later by a summary, for reasons that will become clear at a later date.
Not justified by the introduction of special relativity is a reason to fight the spread of the temptation to step on the meaning of the principle of general relativity have company. But it seems a simple and reliable enough to suggest that, at least for the moment there is little hope of success in such an experiment, we moved to our old friend the car is moving d uniform rate. This is in uniform motion, the passengers of the car makes no sense of movement, and therefore interprets the facts of the case as a notice of detention in May not transport at rest, but the inclination to move. Also varies with the principle of relativity, this interpretation is fully justified and physically.
If the motion of the car is now a non-uniform motion, for example, the effective application of the brakes, then the occupants of the car also suffered a strong shock forward. The delay in opening the mechanical behavior of organisms in relation to the person appearing in the car. The mechanical behavior whose case before the others, and therefore it seems impossible that the same mechanical laws hold to keep the car on uniform motion, as in the car at rest or in uniform motion. In any case, it is clear that the law of Galileo held in connection with non-uniform motion transfer. For this reason, we have now to provide a kind of absolute physical reality to non-uniform motion, contrary to the principle of general relativity. But then, we will see shortly that this demand can be maintained.
The basal principle, which was the pivot of all our previous considerations, was the special principle of relativity, i.e. the principle of the physical relativity of all uniform motion. Let as once more analyze its meaning carefully.
It was at all times clear that, from the point of view of the idea it conveys to us, every motion must be considered only as a relative motion. Returning to the illustration we have frequently used of the embankment and the railway carriage, we can express the fact of the motion here taking place in the following two forms, both of which are equally justifiable :
(a) The carriage is in motion relative to the embankment,
(b) The embankment is in motion relative to the carriage.
In (a) the embankment, in (b) the carriage, serves as the body of reference in our statement of the motion taking place. If it is simply a question of detecting or of describing the motion involved, it is in principle immaterial to what reference-body we refer the motion. As already mentioned, this is self-evident, but it must not be confused with the much more comprehensive statement called “the principle of relativity,” which we have taken as the basis of our investigations.
The principle we have made use of not only maintains that we may equally well choose the carriage or the embankment as our reference-body for the description of any event (for this, too, is self-evident). Our principle rather asserts what follows : If we formulate the general laws of nature as they are obtained from experience, by making use of
(a) the embankment as reference-body,
(b) the railway carriage as reference-body,
then these general laws of nature (e.g. the laws of mechanics or the law of the propagation of light in vacuo) have exactly the same form in both cases. This can also be expressed as follows : For the physical description of natural processes, neither of the reference bodies K, K1 is unique (lit. ” specially marked out “) as compared with the other. Unlike the first, this latter statement need not of necessity hold a priori; it is not contained in the conceptions of ” motion” and ” reference-body ” and derivable from them; only experience can decide as to its correctness or incorrectness.
Up to the present, however, we have by no means maintained the equivalence of all bodies of reference K in connection with the formulation of natural laws. Our course was more on the following lines. In the first place, we started out from the assumption that there exists a reference-body K, whose condition of motion is such that the Galilean law holds with respect to it : A particle left to itself and sufficiently far removed from all other particles moves uniformly in a straight line. With reference to K (Galilean reference-body) the laws of nature were to be as simple as possible. But in addition to K, all bodies of reference K1 should be given preference in this sense, and they should be exactly equivalent to K for the formulation of natural laws, provided that they are in a state of uniform rectilinear and non-rotary motion with respect to K ; all these bodies of reference are to be regarded as Galilean reference-bodies. The validity of the principle of relativity was assumed only for these reference-bodies, but not for others (e.g. those possessing motion of a different kind). In this sense we speak of the special principle of relativity, or special theory of relativity.
In contrast to this we wish to understand by the “general principle of relativity” the following statement : All bodies of reference K, K1, etc., are equivalent for the description of natural phenomena (formulation of the general laws of nature), whatever may be their state of motion. But before proceeding farther, it ought to be pointed out that this formulation must be replaced later by a more abstract one, for reasons which will become evident at a later stage.
Since the introduction of the special principle of relativity has been justified, every intellect which strives after generalization must feel the temptation to venture the step towards the general principle of relativity. But a simple and apparently quite reliable consideration seems to suggest that, for the present at any rate, there is little hope of success in such an attempt; Let us imagine ourselves transferred to our old friend the railway carriage, which is traveling at a uniform rate. As long as it is moving uniformly, the occupant of the carriage is not sensible of its motion, and it is for this reason that he can without reluctance interpret the facts of the case as indicating that the carriage is at rest, but the embankment in motion. Moreover, according to the special principle of relativity, this interpretation is quite justified also from a physical point of view.
If the motion of the carriage is now changed into a non-uniform motion, as for instance by a powerful application of the brakes, then the occupant of the carriage experiences a correspondingly powerful jerk forwards. The retarded motion is manifested in the mechanical behavior of bodies relative to the person in the railway carriage. The mechanical behavior is different from that of the case previously considered, and for this reason it would appear to be impossible that the same mechanical laws hold relatively to the non-uniformly moving carriage, as hold with reference to the carriage when at rest or in uniform motion. At all events it is clear that the Galilean law does not hold with respect to the non-uniformly moving carriage. Because of this, we feel compelled at the present juncture to grant a kind of absolute physical reality to non-uniform motion, in opposition to the general principle of relativity. But in what follows we shall soon see that this conclusion cannot be maintained.The basal principle, which was the pivot of all our previous considerations, was the special principle of relativity, i.e. the principle of the physical relativity of all uniform motion. Let as once more analyze its meaning carefully.
It was at all times clear that, from the point of view of the idea it conveys to us, every motion must be considered only as a relative motion. Returning to the illustration we have frequently used of the embankment and the railway carriage, we can express the fact of the motion here taking place in the following two forms, both of which are equally justifiable :
(a) The carriage is in motion relative to the embankment,
(b) The embankment is in motion relative to the carriage.
In (a) the embankment, in (b) the carriage, serves as the body of reference in our statement of the motion taking place. If it is simply a question of detecting or of describing the motion involved, it is in principle immaterial to what reference-body we refer the motion. As already mentioned, this is self-evident, but it must not be confused with the much more comprehensive statement called “the principle of relativity,” which we have taken as the basis of our investigations.
The principle we have made use of not only maintains that we may equally well choose the carriage or the embankment as our reference-body for the description of any event (for this, too, is self-evident). Our principle rather asserts what follows : If we formulate the general laws of nature as they are obtained from experience, by making use of
(a) the embankment as reference-body,
(b) the railway carriage as reference-body,
then these general laws of nature (e.g. the laws of mechanics or the law of the propagation of light in vacuo) have exactly the same form in both cases. This can also be expressed as follows : For the physical description of natural processes, neither of the reference bodies K, K1 is unique (lit. ” specially marked out “) as compared with the other. Unlike the first, this latter statement need not of necessity hold a priori; it is not contained in the conceptions of ” motion” and ” reference-body ” and derivable from them; only experience can decide as to its correctness or incorrectness.
Up to the present, however, we have by no means maintained the equivalence of all bodies of reference K in connection with the formulation of natural laws. Our course was more on the following lines. In the first place, we started out from the assumption that there exists a reference-body K, whose condition of motion is such that the Galilean law holds with respect to it : A particle left to itself and sufficiently far removed from all other particles moves uniformly in a straight line. With reference to K (Galilean reference-body) the laws of nature were to be as simple as possible. But in addition to K, all bodies of reference K1 should be given preference in this sense, and they should be exactly equivalent to K for the formulation of natural laws, provided that they are in a state of uniform rectilinear and non-rotary motion with respect to K ; all these bodies of reference are to be regarded as Galilean reference-bodies. The validity of the principle of relativity was assumed only for these reference-bodies, but not for others (e.g. those possessing motion of a different kind). In this sense we speak of the special principle of relativity, or special theory of relativity.
In contrast to this we wish to understand by the “general principle of relativity” the following statement : All bodies of reference K, K1, etc., are equivalent for the description of natural phenomena (formulation of the general laws of nature), whatever may be their state of motion. But before proceeding farther, it ought to be pointed out that this formulation must be replaced later by a more abstract one, for reasons which will become evident at a later stage.
Since the introduction of the special principle of relativity has been justified, every intellect which strives after generalization must feel the temptation to venture the step towards the general principle of relativity. But a simple and apparently quite reliable consideration seems to suggest that, for the present at any rate, there is little hope of success in such an attempt; Let us imagine ourselves transferred to our old friend the railway carriage, which is traveling at a uniform rate. As long as it is moving uniformly, the occupant of the carriage is not sensible of its motion, and it is for this reason that he can without reluctance interpret the facts of the case as indicating that the carriage is at rest, but the embankment in motion. Moreover, according to the special principle of relativity, this interpretation is quite justified also from a physical point of view.
If the motion of the carriage is now changed into a non-uniform motion, as for instance by a powerful application of the brakes, then the occupant of the carriage experiences a correspondingly powerful jerk forwards. The retarded motion is manifested in the mechanical behavior of bodies relative to the person in the railway carriage. The mechanical behavior is different from that of the case previously considered, and for this reason it would appear to be impossible that the same mechanical laws hold relatively to the non-uniformly moving carriage, as hold with reference to the carriage when at rest or in uniform motion. At all events it is clear that the Galilean law does not hold with respect to the non-uniformly moving carriage. Because of this, we feel compelled at the present juncture to grant a kind of absolute physical reality to non-uniform motion, in opposition to the general principle of relativity. But in what follows we shall soon see that this conclusion cannot be maintained.