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GregAshmore
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Hello, All. I found this forum through a google search. This post could have been attached to the thread started by Bob Guerico on 09-Jan-08, but I felt it would be better to start a new thread.
I've been reading about SR and GR for about a year now. I've been through several iterations of "I get it" -- "Oh, wait a minute" -- "NOW I get it" -- etc. This has given me a respect for the theory, and an awareness that the conclusions I have reached may be in error. So I ask you, as you read what follows, to keep in mind that I am not on a soapbox. I am presenting for review and criticism my current understanding of SR, the Twin Paradox, and its solution.
I'll present my points in logical order:
[1] The equations of SR are not unique to the theory. They are the equations of Lorentz, derived from a different starting point. Lorentz started with the premise that the speed of light is constant relative to a universally absolute frame of reference; Einstein started with the notion that the speed of light is constant relative to the observer.
[2] Einstein's equation relating energy and mass (E = mc^2) is derived from the Lorentz equations. Therefore, the mass-energy equation is consistent with an absolute frame of reference, on the one hand, and a purely relativistic view of the universe on the other.
[3] Experimental evidence which is consistent with the equations of SR does not prove that the speed of light is constant to the observer, because such evidence is also consistent with the premise that the speed of light is constant relative to an absolute frame of reference.
[4] The distinguishing characteristic of SR is that it allows us to work with the equations of physical phenomena without consideration of an absolute frame of reference. If it were not so, then we would have to take into account our relationship with the absolute frame of reference. Einstein put it this way, "If the principle of relativity does not hold...we should be constrained to believe that natural laws are capable of being formulated in a particularly simple manner, and of course only on condition that, from amongst all possible Galileian coordinate systems, we should have chosen ONE (K0) of a particular state of motion as our body of reference."
[5] The essence of the Twin Paradox is that both observers can be shown to be younger. If the Earth is considered stationary, the observer in the rocket is younger. If the rocket is considered stationary, the observer on the Earth is younger.
[6] The solution to the Twin Paradox is to recognize that one observer is in an inertial frame, while the other is not. The Earth is in an inertial frame because it does not accelerate; the rocket is not in an inertial frame because it does accelerate.
[7] A frame of reference cannot exist by itself. Just as it takes two to tango, it takes two frames to reference. The two frames in the statement of the Twin Paradox are the Earth and the rocket. These frames are accelerating relative to each other, and thus are not inertial with respect to each other.
[8] The solution to the Twin Paradox states that the Earth is in an inertial frame. This implies the introduction of a third frame, relative to which the Earth is not accelerating.
[9] If we accept this solution to the Twin Paradox, we implicitly accept that we cannot correctly formulate the relationship between the Earth and the rocket without taking into account a governing third frame of reference. (See [6] above. Also, consider: How is it that we know the Earth is in an inertial frame? Perhaps it is the rocket which is in the inertial frame. To clarify this point, restate the problem, replacing the Earth with a rocket. How can we tell which rocket is in the inertial frame?)
[10] Thus, the Twin Paradox can only be resolved by abandoning the principle of relativity.
I am open to correction.
Greg
I've been reading about SR and GR for about a year now. I've been through several iterations of "I get it" -- "Oh, wait a minute" -- "NOW I get it" -- etc. This has given me a respect for the theory, and an awareness that the conclusions I have reached may be in error. So I ask you, as you read what follows, to keep in mind that I am not on a soapbox. I am presenting for review and criticism my current understanding of SR, the Twin Paradox, and its solution.
I'll present my points in logical order:
[1] The equations of SR are not unique to the theory. They are the equations of Lorentz, derived from a different starting point. Lorentz started with the premise that the speed of light is constant relative to a universally absolute frame of reference; Einstein started with the notion that the speed of light is constant relative to the observer.
[2] Einstein's equation relating energy and mass (E = mc^2) is derived from the Lorentz equations. Therefore, the mass-energy equation is consistent with an absolute frame of reference, on the one hand, and a purely relativistic view of the universe on the other.
[3] Experimental evidence which is consistent with the equations of SR does not prove that the speed of light is constant to the observer, because such evidence is also consistent with the premise that the speed of light is constant relative to an absolute frame of reference.
[4] The distinguishing characteristic of SR is that it allows us to work with the equations of physical phenomena without consideration of an absolute frame of reference. If it were not so, then we would have to take into account our relationship with the absolute frame of reference. Einstein put it this way, "If the principle of relativity does not hold...we should be constrained to believe that natural laws are capable of being formulated in a particularly simple manner, and of course only on condition that, from amongst all possible Galileian coordinate systems, we should have chosen ONE (K0) of a particular state of motion as our body of reference."
[5] The essence of the Twin Paradox is that both observers can be shown to be younger. If the Earth is considered stationary, the observer in the rocket is younger. If the rocket is considered stationary, the observer on the Earth is younger.
[6] The solution to the Twin Paradox is to recognize that one observer is in an inertial frame, while the other is not. The Earth is in an inertial frame because it does not accelerate; the rocket is not in an inertial frame because it does accelerate.
[7] A frame of reference cannot exist by itself. Just as it takes two to tango, it takes two frames to reference. The two frames in the statement of the Twin Paradox are the Earth and the rocket. These frames are accelerating relative to each other, and thus are not inertial with respect to each other.
[8] The solution to the Twin Paradox states that the Earth is in an inertial frame. This implies the introduction of a third frame, relative to which the Earth is not accelerating.
[9] If we accept this solution to the Twin Paradox, we implicitly accept that we cannot correctly formulate the relationship between the Earth and the rocket without taking into account a governing third frame of reference. (See [6] above. Also, consider: How is it that we know the Earth is in an inertial frame? Perhaps it is the rocket which is in the inertial frame. To clarify this point, restate the problem, replacing the Earth with a rocket. How can we tell which rocket is in the inertial frame?)
[10] Thus, the Twin Paradox can only be resolved by abandoning the principle of relativity.
I am open to correction.
Greg