The Thomas precession (TP) is a kinematic effect since its definition does not include underlying causes. However, that does not mean that TP does not have underlying causes.
The problem we have is that 'kinematic effects' are always accompanied by underlying causes. Some scientists, maybe including Thomas himself in 1923, insist that there are no torques or forces in TP. This is not true. So one can discuss the underlying causes of TP.
The Thomas Precession is always accompanied by torques and forces. TP can not occur unless the forces and torques are present.
The Thomas precession is a kinematic effect. However, it is always accompanied by dynamic effects. Here is a link and quote.
http://ift.tt/1pPJe1v
‘Thomas precession is a kinematic effect in the flat spacetime of special relativity. In the curved spacetime of general relativity, Thomas precession combines with a geometric effect to produce de Sitter precession. Although Thomas precession (net rotation after a trajectory that returns to its initial velocity) is a purely kinematic effect, it only occurs in curvilinear motion and therefore cannot be observed independently of some centripetal force causing the curvilinear motion such as that caused by an electromagnetic field, a gravitational field or a mechanical force, so Thomas precession is always accompanied by dynamical effects.’
Kinematic and dynamics refer to the interests of the physicist making the calculation rather than the physical phenomenon itself. Kinematics is a analysis of a phenomenon with no reference to the underlying cause. Kinematics usually involves position, angle, linear velocity or angular velocity. Dynamics is an analysis of a phenomenon involving the underlying cause. ‘Underlying causes’ include forces and torques.
The dividing line between kinematics and dynamics has to do with what the scientist choses to ignore rather than what happens in the phenomenon. The Thomas precession is defined in terms of angles and position. Neither angle nor position are considered underlying cause. So TP is called a ‘kinematic phenomenon’. However, the TP is accompanied by forces and torques. These forces and torques can be considered the underlying causes.
You can’t have TP without forces and torques. You can if you wish ignore them. However, the torques that accompany TP can change the angular momentum of individual bodies in the system. However, torques can’t change the TOTAL angular momentum of a system.
Here are links on kinematics and dynamics. Note that the terms refer to the calculated quantities, not the phenomenon itself.
http://ift.tt/10eTeqi
‘Kinematics is the branch of classical mechanics which describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion.[1][2][3] The term is the English version of A.M. Ampère's cinématique,[4] which he constructed from the Greek κίνημα kinema "movement, motion", derived from κινεῖν kinein "to move".[5][6]
The study of kinematics is often referred to as the geometry of motion.’
http://ift.tt/1xbcMh5(mechanics)
‘Dynamics is a branch of physics (specifically classical mechanics) concerned with the study of forces and torques and their effect on motion, as opposed to kinematics, which studies the motion of objects without reference to its causes.’
The suggestion was made in another thread that forces and torques can't accompany TP because an accelerating frame can be assembled from inertial frames. However, the composite observer that is assembled from separate inertial frames is in effect an accelerating frame. One has to synchronize the separate inertial frames in a precise way in order to construct a self consistent
Building a composite observer out of separate components does not eliminate the necessary torques and forces. Assembling a composite observer out of separate inertial frames in effect 'creates' forces and torques.
A composite system does not have the same properties as the components that comprise it. A closed polygon remains a closed polygon even if its is comprised of straight line segments. Isaac Newton used this principle when he calculated orbits in the solar system. Similarly, a rotating frame remains a rotating frame even if it is comprised of segments from inertial frames. Einstein used this is special relativity to analyze 'time dilation'.
So the forces and torques that accompany TP don't vanish if its is described in a composite frame of reference. The composite frame of reference is an accelerating frame of reference.
In any one inertial frame of reference, TP is accompanied by forces and torques. So there are underlying causes of TP.
The problem we have is that 'kinematic effects' are always accompanied by underlying causes. Some scientists, maybe including Thomas himself in 1923, insist that there are no torques or forces in TP. This is not true. So one can discuss the underlying causes of TP.
The Thomas Precession is always accompanied by torques and forces. TP can not occur unless the forces and torques are present.
The Thomas precession is a kinematic effect. However, it is always accompanied by dynamic effects. Here is a link and quote.
http://ift.tt/1pPJe1v
‘Thomas precession is a kinematic effect in the flat spacetime of special relativity. In the curved spacetime of general relativity, Thomas precession combines with a geometric effect to produce de Sitter precession. Although Thomas precession (net rotation after a trajectory that returns to its initial velocity) is a purely kinematic effect, it only occurs in curvilinear motion and therefore cannot be observed independently of some centripetal force causing the curvilinear motion such as that caused by an electromagnetic field, a gravitational field or a mechanical force, so Thomas precession is always accompanied by dynamical effects.’
Kinematic and dynamics refer to the interests of the physicist making the calculation rather than the physical phenomenon itself. Kinematics is a analysis of a phenomenon with no reference to the underlying cause. Kinematics usually involves position, angle, linear velocity or angular velocity. Dynamics is an analysis of a phenomenon involving the underlying cause. ‘Underlying causes’ include forces and torques.
The dividing line between kinematics and dynamics has to do with what the scientist choses to ignore rather than what happens in the phenomenon. The Thomas precession is defined in terms of angles and position. Neither angle nor position are considered underlying cause. So TP is called a ‘kinematic phenomenon’. However, the TP is accompanied by forces and torques. These forces and torques can be considered the underlying causes.
You can’t have TP without forces and torques. You can if you wish ignore them. However, the torques that accompany TP can change the angular momentum of individual bodies in the system. However, torques can’t change the TOTAL angular momentum of a system.
Here are links on kinematics and dynamics. Note that the terms refer to the calculated quantities, not the phenomenon itself.
http://ift.tt/10eTeqi
‘Kinematics is the branch of classical mechanics which describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion.[1][2][3] The term is the English version of A.M. Ampère's cinématique,[4] which he constructed from the Greek κίνημα kinema "movement, motion", derived from κινεῖν kinein "to move".[5][6]
The study of kinematics is often referred to as the geometry of motion.’
http://ift.tt/1xbcMh5(mechanics)
‘Dynamics is a branch of physics (specifically classical mechanics) concerned with the study of forces and torques and their effect on motion, as opposed to kinematics, which studies the motion of objects without reference to its causes.’
The suggestion was made in another thread that forces and torques can't accompany TP because an accelerating frame can be assembled from inertial frames. However, the composite observer that is assembled from separate inertial frames is in effect an accelerating frame. One has to synchronize the separate inertial frames in a precise way in order to construct a self consistent
Building a composite observer out of separate components does not eliminate the necessary torques and forces. Assembling a composite observer out of separate inertial frames in effect 'creates' forces and torques.
A composite system does not have the same properties as the components that comprise it. A closed polygon remains a closed polygon even if its is comprised of straight line segments. Isaac Newton used this principle when he calculated orbits in the solar system. Similarly, a rotating frame remains a rotating frame even if it is comprised of segments from inertial frames. Einstein used this is special relativity to analyze 'time dilation'.
So the forces and torques that accompany TP don't vanish if its is described in a composite frame of reference. The composite frame of reference is an accelerating frame of reference.
In any one inertial frame of reference, TP is accompanied by forces and torques. So there are underlying causes of TP.
via International Skeptics Forum http://ift.tt/1D8YcHn
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