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#1
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This is directly implied by Newton's First Law, which does away with
absolute velocity. If there is no way to measure absolute velocity, there can be no absolute reference frame, and all inertial frames must be equivalent. If they weren't, then a system would evolve in different ways depending on who/what 'looked' at it. This is an absurd notion. To paraphrase Hawking (I think it was in A Brief History Of Time), 'Any passing sub-atomic particle could cause entire star systems to collapse.' Absolute velocity does not disallow equivalent intertial reference frames. Furthermore, Newton's first law is WRONG. To say that bodies have default linear motion is in total contradiction with observation. Not to mention the fact that Newtons third law is a logical fallacy. A forces opposing force cannot be itself and it cannot be not itself. Otherwise the notion of cause is totally lost or the cause ends up creating an infinity of separate opposing forces of equal magnitude which would make no sense either. Enough said of the first postulate. The second postulate, that the speed of light is constant in all such frames: This is actually an extension of the first postulate, as the speed of light is determined by the laws of physics. First, remember the process by which light was realised to be electromagnetic in nature. Speed of light has been observed to vary. So transistively, relativity is wrong. Maxwell, from his equations of electromagnetism, realised that a combination of an electric and magnetic field could propagate through space without a conductor or a magnet present. If you do the maths, it turns out that this disturbance MUST propagate at the speed of light, or it wouldn't 'work'. Because the speed of light was fairly well known, and agreed with Maxwell's predictions of electromagnetic waves, it was suggested that light WAS these waves. Subsequent experiments proved it. Maxwell got it wrong. Delbruck scattering is well known and even a 12 year old can infer that for a particle to move in a discontinuous path then it must have changed velocity magnitude at that point. So, with all inertial frames being equivalent, and light only being ABLE to propagate at c, SR is the only possible answer. The fact that a century of experiments have agreed again and again with relativity only confirms this. I can confirm anything when all discrepencies in theory result in the "discovery" of fantastical new entities (i.e. dark matter). Regards to all P.S. Note that GR came about from (sort of) applying SR to accelerating reference frames, and must consequently also be correct. |
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#2
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#3
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Newton's Third Law is the statement that all forces can be paired in such
a manner that each force in a pair is a reaction to the other. If F2 is the counter-force to F1, then F1 and F2 make up one of these pairs, and so the counter-force to F2 is the other force in the pair, i.e. F1. This means that Newton's Third Law does apply: it is just the guarantee that every force can be paired with another force. F1's mate in its pair is F2. F2's mate in its pair is F1. If two equal and opposing forces occur simultaneously at the point of collision of two point particles, then those two particles are bound at the same point after the collision as the opposing forces cancel each other out. The result is two different point particles existing at the same point causing an infinity of further collisions. When did causality become a non-issue in the study of physical science? |
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#4
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#5
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#6
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John Schoenfeld wrote: Absolute velocity does not disallow equivalent intertial reference frames. Furthermore, Newton's first law is WRONG. To say that bodies have default linear motion is in total contradiction with observation. Not to mention the fact that Newtons third law is a logical fallacy. A forces opposing force cannot be itself and it cannot be not itself. Dolt! The forces of Newton's third law are separate. Body A acts on body B and body B acts on body A with distinct forces, equal in magnitude and opposite direction. The 3-rd law is the conservation of classical momentum stated in other terms. It turns out the momentum must be defined in a relativistic manner for conservation to hold. As to the first and second law they are correct. One cannot distinguish between rest and uniform motion where there is no net force or acceleration. That is the whole point which Aristotle missed. He concluded that -any- motion requires a force. Not so. Otherwise the notion of cause is totally lost or the cause ends up creating an infinity of separate opposing forces of equal magnitude which would make no sense either. You are blovating. For low velocity motions Newton's laws are experimentally verified. Enough said of the first postulate. The second postulate, that the speed of light is constant in all such frames: This is actually an extension of the first postulate, as the speed of light is determined by the laws of physics. First, remember the process by which light was realised to be electromagnetic in nature. Speed of light has been observed to vary. So transistively, relativity is wrong. Not in free space. The speed of light as measured by any known means is constant in free space when measure in inertial frames. Bob Kolker Maxwell, from his equations of electromagnetism, realised that a combination of an electric and magnetic field could propagate through space without a conductor or a magnet present. If you do the maths, it turns out that this disturbance MUST propagate at the speed of light, or it wouldn't 'work'. Because the speed of light was fairly well known, and agreed with Maxwell's predictions of electromagnetic waves, it was suggested that light WAS these waves. Subsequent experiments proved it. Maxwell got it wrong. Delbruck scattering is well known and even a 12 year old can infer that for a particle to move in a discontinuous path then it must have changed velocity magnitude at that point. So, with all inertial frames being equivalent, and light only being ABLE to propagate at c, SR is the only possible answer. The fact that a century of experiments have agreed again and again with relativity only confirms this. I can confirm anything when all discrepencies in theory result in the "discovery" of fantastical new entities (i.e. dark matter). Regards to all P.S. Note that GR came about from (sort of) applying SR to accelerating reference frames, and must consequently also be correct. |
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#8
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(John Schoenfeld) writes:
(David McAnally) wrote in message ... (John Schoenfeld) writes: Newton's Third Law is the statement that all forces can be paired in such a manner that each force in a pair is a reaction to the other. If F2 is the counter-force to F1, then F1 and F2 make up one of these pairs, and so the counter-force to F2 is the other force in the pair, i.e. F1. This means that Newton's Third Law does apply: it is just the guarantee that every force can be paired with another force. F1's mate in its pair is F2. F2's mate in its pair is F1. If two equal and opposing forces occur simultaneously at the point of collision of two point particles, then those two particles are bound at the same point after the collision as the opposing forces cancel each other out. Rubbish. The forces do NOT act on the same particle. One of the forces affects the motion of one of the particles, and the other force affects the motion of the other particle. They do NOT affect the SAME particle, so your assessment above is complete garbage since it assumes something which is not true. At a point collision of two point particles, if a force and its equal opposite are caused simultaneously as you say, then those forces cannot be superpositional as they would otherwise not exist (i.e. they would cancel each other out at that point IRRESPECTIVE of the bodies involved in the collision.) If you deny this behaviour then you deny the superposition principle. Wrong. The superposition principle states that the nett force on a body is equal to the superposition of the forces acting on the body, so that the time-derivative of the momentum of a body is the superposition of all the forces acting on the body. More generally, the nett force on a system of bodies is equal to the superposition of all the forces exerted on bodies internal to the system by bodies external to the system, so the time-derivative of the momentum of a system is equal to the superposition of all forces exerted on bodies internal to the system by bodies external to the system. The superposition principle tells us absolutely nothing about the internal dynamics of the bodies within a system. It only tells you about the time-derivative of the nett momentum of the system. Since a single body is a special case of a dynamical system, then I will give justification in the general case. First of all, Newton's Second Law of Motion tells us that the time-derivative of the momentum of a body is equal to the superposition of the forces acting on the body. Suppose a force F is exerted on a body A by a body B, and both bodies are internal to the system, then the partner of F in its pair is a force G, equal in magnitude and opposite in direction, which is exerted on the body B by the body A. It follows that the contribution to the time-derivative of the sum of the momenta of A and B from F and G is zero, as these forces cancel. So, upon defining the nett momentum of a system as the sum of the momenta of the individual component bodies, all forces exerted on bodies internal to the system by bodies internal to the system cancel in pairs. On the other hand, if a force F is exerted on a body A by a body C, and the body A is internal to the system and the body C is external to the system, then F contributes to the time-derivative of the sum of the momenta of the bodies in the system, and so to the time-derivative of the nett momentum of the system. On the other hand, the partner G of F in its pair is a force exerted on the body C by the body A, and so it is exerted on a body external to the system and does not contribute to the time-derivative of the sum of the momenta of the bodies of the system, and so it does not contribute to the time-derivative of the nett momentum of the system. In short, the time-derivative of the momentum of the system equals the sum of the time-derivatives of the momenta of the bodies which make up the system, which equals the superposition of the forces which are exerted on the bodies of the system. By Newton's Third Law of Motion, the forces between bodies internal to the system cancel each other in pairs. This leaves the forces exerted on bodies internal to the system by bodies external to the system, so that the time-derivative of the nett momentum of the system is equal to the superposition of the forces exerted on bodies internal to the system by bodies external to the system. The important point to note is that while the superposition determines the time-derivative of the nett momentum of the system, it has no bearing on the dynamics of the bodies within the system, since there is not enough information to determine the behaviour of the individual bodies. This means that because the forces cancel in a collision, then the momentum of the system of the two particles is conserved, but it gives you no additional information about the motion of the individual particles, so you can't make the assertion that you did. The result is two different point particles existing at the same point causing an infinity of further collisions. When did causality become a non-issue in the study of physical science? Maybe it started for you when you started making assumptions which were not true, just like you did above. Most of physics is based on assumptions (e.g. Newtons 1st law is true). Physical theories are based on axioms and postulates. Newton built his Theory of Mechanics from certain axioms, which included his Three Laws of Motion. The Theory was then used to make certain predictions, and these predictions could be tested. Newtonian Mechanics is a consistent theory. On the other hand, you tried to add an assumption to the framework of the already established theory, and the assumption that you tried to add was inconsistent with that theory, and now you are attempting to condemn the theory as inconsistent merely because it happens to be inconsistent with your added assumption. Instead of condemning Newtonian Mechanics just because your own personal interpretation of the Laws is inconsistent, it would be better for you to take the trouble to learn the correct interpretation of the laws, and to understand, for example, that the superposition of forces exerted on internal bodies of a system by external bodies gives you no other information than the time-derivative of the total momentum of the system, and specifically, it gives you no additional information about the motion of the specific bodies in the system. David McAnally -------------- |
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#9
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1. There exists two point masses moving towards each other.
2. At time T they collide at point P. 3. At time T two simultaneously paired opposite forces of equal magnitude occur at point P. This is a contact force. On a side note, in Special Relativity, all forces are contact forces. 4. ________ Fill in the blanks. Point mass 1 exerts a force on point mass 2, and point mass 2 exerts the paired force on point mass 1. The motion of point mass 1 is affected by the force exerted on it by point mass 2. Since the force exerted on point mass 2 by point mass 1 is not on point mass 1, then it has no effect on the motion of point mass 1. While you continue to consider that there is no effect of two paired contact forces on a system because they balance, then you are not doing Newtonian Mechanics, because you are making an assumption which is contradictory to Newtonian Mechanics (specifically, it is contradictory to Newton's Second Law of Motion). You still have it all wrong. POINT mass A has mass Ma. POINT mass B has mass Mb. At time t, a collision occurs at POINT p. So at time t we observe mass A and mass B existing simultaneously at point P. An equivalent observation would be that there exists a SINGLE POINT mass C with mass Ma+Mb existing at point P at time t. Also at time t, we have the paired force as predicted by Newtons 3rd law. Given that there is a single point mass at point p, then the superposition principle applies and the paired forces cancel each other out as predicted. Do you see the problem yet? Newton's Three Laws of Motion: 1. If a body has no forces acting on it, then it either remains stationary or it moves uniformly. Empirical evidence implies otherwise. 2. The time-derivative of the momentum of a body is equal to the sum of the forces which are exerted on the body. Contact forces can never exist as they are always cancelled out at the point of contact. 3. Forces are paired in such a manner that the forces in a pair are equal in magnitude and opposite in direction. The two forces in a pair are caused by the same mechanism. The same body experiences one of the forces and exerts the other, so that if one force in a pair is exerted on body A by body B, then the other force in the pair is exerted on body B by body A. The problem with Newtons laws is that they do not define what a body is and isn't. Newtons laws do not prohibit the existence of point masses, and the above analysis I've showed clearly outlines a logical fallacy with these laws. |
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#10
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