Solving the twin paradox with special relativity

In summary, the conversation discusses the twin paradox and how special relativity can be used to solve it. The process of the twin paradox is divided into three stages: navigating to a black hole, turning around, and returning home. The observer in the spacecraft experiences time dilation and concludes that the twin on Earth will age slower. However, the situation is not completely symmetric due to the acceleration experienced by the traveling twin. The Lorentz Transformation and rules on time dilation and length contraction apply when measuring in an Inertial Reference Frame (IRF).
  • #36
PeterDonis said:
When in doubt, it's best to not use words that can be ambiguous, but just to directly describe what you're measuring and how you're measuring it. Saying you're timing round-trip light signals, or saying you're using an accelerometer, makes it clear what you're measuring without having to worry about the ambiguity of terms like "experience" or "acceleration".
ok; thank you for your time and patience, Peter.
 
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  • #37
Grampa Dee said:
I understand; however, acceleration, for me, is first and foremost a change in velocity, which is usually measured with measuring rods (or light signals) as opposed to forces, and so I visualized more the experience of acceleration with measuring velocities...again, it's not easy for me to express myself scientifically due to the exactitude in speech that is needed.
In non-inertial coordinate systems, it is very important to distinguish between the derivative of velocity (second derivative of position) versus the physical acceleration that can be used in F=mA. That is especially true with a rotating coordinate system, where the derivative of velocity can be huge even though there is no external force at all.
Additionally, in the context of SR, you need to start thinking about spacetime coordinates rather than simple spatial position coordinates. With simple spatial position coordinates, it is mathematically easy to think of the positions, velocities, and accelerations as all being relative. In spacetime that is no longer true. In spacetime, an accelerating path is easily distinguished from a nonaccelerating path without referring to any other reference frame. So accelerations are not relative in spacetime coordinate systems.
 
  • #38
FactChecker said:
In non-inertial coordinate systems, it is very important to distinguish between the derivative of velocity (second derivative of position) versus the physical acceleration that can be used in F=mA. That is especially true with a rotating coordinate system, where the derivative of velocity can be huge even though there is no external force at all.
Additionally, in the context of SR, you need to start thinking about spacetime coordinates rather than simple spatial position coordinates. With simple spatial position coordinates, it is mathematically easy to think of the positions, velocities, and accelerations as all being relative. In spacetime that is no longer true. In spacetime, an accelerating path is easily distinguished from a nonaccelerating path without referring to any other reference frame. So accelerations are not relative in spacetime coordinate systems.
thank you FactChecker
 

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