Special relativity and apparent, actual and synchronized positions

bernhard.rothenstein
Messages
991
Reaction score
1
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 aparent. 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
 
Physics news on Phys.org
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 aparent. 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.
 
I started reading a National Geographic article related to the Big Bang. It starts these statements: Gazing up at the stars at night, it’s easy to imagine that space goes on forever. But cosmologists know that the universe actually has limits. First, their best models indicate that space and time had a beginning, a subatomic point called a singularity. This point of intense heat and density rapidly ballooned outward. My first reaction was that this is a layman's approximation to...
Thread 'Dirac's integral for the energy-momentum of the gravitational field'
See Dirac's brief treatment of the energy-momentum pseudo-tensor in the attached picture. Dirac is presumably integrating eq. (31.2) over the 4D "hypercylinder" defined by ##T_1 \le x^0 \le T_2## and ##\mathbf{|x|} \le R##, where ##R## is sufficiently large to include all the matter-energy fields in the system. Then \begin{align} 0 &= \int_V \left[ ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g}\, \right]_{,\nu} d^4 x = \int_{\partial V} ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g} \, dS_\nu \nonumber\\ &= \left(...
In Philippe G. Ciarlet's book 'An introduction to differential geometry', He gives the integrability conditions of the differential equations like this: $$ \partial_{i} F_{lj}=L^p_{ij} F_{lp},\,\,\,F_{ij}(x_0)=F^0_{ij}. $$ The integrability conditions for the existence of a global solution ##F_{lj}## is: $$ R^i_{jkl}\equiv\partial_k L^i_{jl}-\partial_l L^i_{jk}+L^h_{jl} L^i_{hk}-L^h_{jk} L^i_{hl}=0 $$ Then from the equation: $$\nabla_b e_a= \Gamma^c_{ab} e_c$$ Using cartesian basis ## e_I...

Similar threads

Replies
20
Views
2K
Replies
31
Views
2K
Replies
7
Views
1K
Replies
22
Views
2K
Replies
54
Views
3K
Replies
15
Views
3K
Back
Top