Length contraction of distant objects/space, etc

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Discussion Overview

The discussion explores the concept of length contraction in the context of special relativity, particularly as it pertains to objects in motion at relativistic speeds. Participants examine whether distant objects, such as stars and planets, experience contraction as one moves towards them, and how this contraction behaves based on the observer's velocity and direction of travel.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether all objects ahead in the path of travel are contracted for an infinite distance as one moves at a significant fraction of the speed of light.
  • Another participant suggests that the Lorentz transformation behaves like an instantaneous rotation in space, implying that objects appear to change position relative to the observer's movement.
  • Some participants assert that objects remain contracted until the observer slows down, while others clarify that contraction occurs along the axis parallel to the observer's velocity vector.
  • There is a query about whether the entire universe or just objects contract, with references to differences between Einstein's and Lorentz's theories regarding contraction.
  • Participants discuss the implications of contraction for objects at angles to the observer's path, with some expressing uncertainty about how contraction manifests in such cases.

Areas of Agreement / Disagreement

Participants express differing views on the nature of contraction, particularly regarding whether it applies to space itself or only to objects. There is no consensus on the specifics of how contraction behaves for objects not directly in front of the observer, indicating ongoing debate.

Contextual Notes

Participants reference various interpretations of length contraction and the Lorentz transformation, with some assumptions about the nature of space and motion remaining unaddressed. The discussion includes speculative elements regarding the behavior of objects at angles to the observer's path.

coktail
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If I am moving through space at a velocity that is a significant fraction of c, are all objects ahead of me in my path contracted in the direction of my travel for an infinite distance? In other words, are planets and stars from right in front of me to the edge of the known universe contracted as I move towards them?

What about once I'm past them? Do they remained contracted until I slow down?

Does this contraction decrease if an object is not directly in front of me, but off to the side a bit?

As always, thank you.
 
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The Lorentz transformation is the equivalent of a rotation in ordinary space. It does not propagate at the speed of light; it is "instantaneous."

Compare, for example, this scenario: you are moving in a 2d plane that has no absolute coordinate system (no notion of north, south, east, or west) just what's ahead of you, what's behind, what's left and what's right. When you turn, all objects on this plane rotate as well, instantaneously as you do. If you have an object 5 miles ahead of you and you turn 45 degrees to the right, the object is then ~3.5 miles ahead of you and ~3.5 miles to your left.
 
coktail said:
If I am moving through space at a velocity that is a significant fraction of c, are all objects ahead of me in my path contracted in the direction of my travel for an infinite distance? In other words, are planets and stars from right in front of me to the edge of the known universe contracted as I move towards them?
Yes.

What about once I'm past them? Do they remained contracted until I slow down?
Yes.

Does this contraction decrease if an object is not directly in front of me, but off to the side a bit?
It contracts along the axis parallel to your velocity vector.

As always, thank you.
 
Thanks!

Does the entire universe (including space itself) in my path contract, or just objects?

Can someone please elaborate on "it contracts along the axis parallel to your velocity vector" for me? What I take this to mean is that an item at an angle to me would contract at an angle, but that may be totally wrong.
 
If you're pointing in the x-direction, other objects will contract in the x-direction regardless of where they are.
 
coktail said:
Thanks!

Does the entire universe (including space itself) in my path contract, or just objects?s
Yes, that is the crucial difference between Einstein's theory and Lorentz's theory: the distance between two objects contracts as well as the objects.

Can someone please elaborate on "it contracts along the axis parallel to your velocity vector" for me? What I take this to mean is that an item at an angle to me would contract at an angle, but that may be totally wrong.
I'm not sure what you mean by "contract at an angle". If you are at (0,0) in some coordinate system moving in the positive y direction, an object that, to a stationary observor, is a rectangle with vertices at (1, 1), (2, 1), (1, 4), and (2, 4), it will appear to you to occupy [itex](1, 1- \beta), (2, 1- \beta), (1, 4- \beta), (2, 4- \beta)[/itex].
 

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