Special relativity and apparent, actual and synchronized positions

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SUMMARY

This discussion focuses on the application of Lorentz transformations to analyze the positions and timings of a moving particle and a light signal in the context of special relativity. The particle moves with speed V along the OX axis, with its apparent position at xa and actual position at xa(1+V/c). The events E1 and E2 are defined, with their coordinates transformed to the rest frame of the moving particle using the Lorentz factor g. The derivations presented are confirmed as correct and illustrate fundamental principles of special relativity.

PREREQUISITES
  • Understanding of special relativity concepts, including Lorentz transformations
  • Familiarity with the Lorentz factor (g) and its calculation
  • Knowledge of space-time coordinates and their significance in physics
  • Basic grasp of light signal propagation and its implications in relativistic contexts
NEXT STEPS
  • Study the derivation and implications of the Lorentz transformations in detail
  • Explore the concept of simultaneity in different inertial frames
  • Investigate the physical interpretations of apparent vs. actual positions in relativity
  • Learn about the implications of relativistic effects on time dilation and length contraction
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This discussion is beneficial for physics students, educators, and researchers interested in the principles of special relativity, particularly those focusing on the mathematical foundations and applications of Lorentz transformations.

bernhard.rothenstein
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Consider a particle that moves with speed V in the positive direction of the OX axis of the inertial reference frame I. At a time t=0 it is located at a point Ma characterized by a apace coordinate xa. Using a terminology proposed by Deissler1 we call that position apparent. At t=0 a light signal is emitted from the origin O in the positive direction of the OX axis. Its arrival at the point Ma is associated with event E1 characterized by a space coordinate xa and by a time coordinate xa and by a time coordinate xa/c. At that very time the moving particle arrives at its actual position associated with an event E2 characterized by a space coordinate xa(1+V/c) taking into account that during the time interval xa/c the moving particle has advances with Vxa/c, and by a time coordinate xa/c. The two events are simultaneous in I.
Performing the Lorentz transformation of the space-time coordinates of event E2
to the rest frame I' of the moving partcle the results are
x'=gxa=gcta (1)
and
t'=gta[1-V/c(1+V/c)]=gxa[1-V/c(1+V/c)] (2)
g standing for the Lorentz factor. If we neglect second order effects (2) becomes
t'=ta[(1-V/c)/(1+V/c)]1/2 (3)
Let E be the event associated with the fact that the world lines of the moving particle and of the propagating light signal intersect each other. Let x be its space coordinate. From
x=xa+Vx/c (4)
we obtain that
x=xa/(1-V/c) (5)
event E being characterized by a time coordinate
 
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bernhard.rothenstein said:
Consider a particle that moves with speed V in the positive direction of the OX axis of the inertial reference frame I. At a time t=0 it is located at a point Ma characterized by a apace coordinate xa. Using a terminology proposed by Deissler1 we call that position apparent. At t=0 a light signal is emitted from the origin O in the positive direction of the OX axis. Its arrival at the point Ma is associated with event E1 characterized by a space coordinate xa and by a time coordinate xa and by a time coordinate xa/c. At that very time the moving particle arrives at its actual position associated with an event E2 characterized by a space coordinate xa(1+V/c) taking into account that during the time interval xa/c the moving particle has advances with Vxa/c, and by a time coordinate xa/c. The two events are simultaneous in I.
Performing the Lorentz transformation of the space-time coordinates of event E2
to the rest frame I' of the moving partcle the results are
x'=gxa=gcta (1)
and
t'=gta[1-V/c(1+V/c)]=gxa[1-V/c(1+V/c)] (2)
g standing for the Lorentz factor. If we neglect second order effects (2) becomes
t'=ta[(1-V/c)/(1+V/c)]1/2 (3)
Let E be the event associated with the fact that the world lines of the moving particle and of the propagating light signal intersect each other. Let x be its space coordinate. From
x=xa+Vx/c (4)
we obtain that
x=xa/(1-V/c) (5)
event E being characterized by a time coordinate x/c. Performing the Lorentz transformations to the rest frame of the moving particle we obtain
x'=gxa
t'=gxa/c (6)
Do you consider that the derivations above are correct? Are they a simple exercise in handling the Lorentz transformations or there is some physics behind them.
Thanks in advance for your help.
 

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