Rindler coordinates in Minkowski spacetime

Click For Summary

Discussion Overview

The discussion revolves around Rindler coordinates in Minkowski spacetime, focusing on the properties of inertial and Rindler observers, the nature of acceleration, and the implications of these coordinates on communication and horizons. The scope includes theoretical aspects of spacetime geometry and the behavior of observers in different frames of reference.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants describe the metrics for inertial and Rindler coordinates in Minkowski spacetime, noting the differences in perspectives of observers.
  • Questions are raised about how to prove that an observer at fixed ##R## has a fixed acceleration.
  • There is inquiry into why Rindler coordinates only cover the right wedge of Minkowski space and not the other regions.
  • Participants discuss the possibility of communication between Minkowski and Rindler observers, using analogies such as an elevator scenario.
  • Some participants assert that an inertial observer at fixed ##x## is not following a geodesic, while others challenge this claim, suggesting that such an observer is indeed following a geodesic.

Areas of Agreement / Disagreement

There is disagreement regarding the nature of inertial observers and whether they follow geodesics. Some participants maintain that inertial observers are stationary and not on geodesics, while others argue that constant velocity observers do follow geodesics.

Contextual Notes

Participants have not reached a consensus on several key questions, including the nature of acceleration for Rindler observers and the implications of Rindler coordinates on communication with Minkowski observers.

spaghetti3451
Messages
1,311
Reaction score
31
In an inertial coordinate system in two-dimensional Minkowski spacetime, the metric takes the form
$$(ds)^{2} = - (dt)^{2} + (dx)^{2},$$
and in an accelerating coordinate system in two-dimensional Minkowski spacetime, the metric takes the form
$$(ds)^{2} = - R^{2}(d\eta)^{2} + (dR)^{2}.$$
The coordinates ##t## and ##x## are called inertial coordinates and the coordinates ##\eta## and ##R## are called Rindler coordinates.

These coordinates describe the line element of Minkowski spacetime from the perspective of an inertial observer and of an accelerating observer respectively.
-------------------------------------------------------------------------------
Rindler coordinates in Minkowski spacetime are related to inertial coordinates in Minkowski spacetime by the change of coordinates
$$x = R\cosh\eta, \qquad t = R\sinh\eta.$$
-------------------------------------------------------------------------------
An inertial observer is an observer sitting at fixed ##x##. This is not a geodesic - it is a stationary trajectory.

A Rindler observer is an observer sitting at fixed ##R##. This is not a geodesic - it is a uniformly accelerating trajectory.
-------------------------------------------------------------------------------
1. How can you prove that an observer sitting at fixed ##R## has a fixed acceleration?

2. How can you prove that the Rindler coordinates only cover the right wedge of Minkowski space? Why don't Rindler coordinates cover the other three patches of Minkowski space?

3. Can a Minkowski observer ever communicate with a Rindler observer?

4. Why do Rindler observers see a horizon at ##R = 0##? How is this horizon similar to a black hole horizon?
 
Physics news on Phys.org
Did you try to map curves of constant-##R## or constant-##\eta## into an ordinary spacetime diagram?
Given the trajectory of a particle, can you determine the velocity and acceleration?
 
spaghetti3451 said:
An inertial observer is an observer sitting at fixed ##x##. This is not a geodesic - it is a stationary trajectory.
Are you sure of this?
 
  • Like
Likes   Reactions: vanhees71
spaghetti3451 said:
. How can you prove that an observer sitting at fixed R has a fixed acceleration?
Just calculate the proper acceleration and show that it is constant wrt time.

spaghetti3451 said:
3. Can a Minkowski observer ever communicate with a Rindler observer?
If you and a friend are in an elevator and one of you jumps do you expect an interruption in communication?
 
Last edited:
An inertial observer is an observer sitting at fixed ##x##. This is not a geodesic - it is a stationary trajectory.

Huh? An observer in an inertial frame with a constant velocity (including a constant velocity of zero) is following a geodesic.
 
  • Like
Likes   Reactions: cianfa72 and vanhees71

Similar threads

Replies
8
Views
2K
  • · Replies 16 ·
Replies
16
Views
4K
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K