Hypothetical implication of Lorentz contraction

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Discussion Overview

The discussion revolves around the hypothetical implications of Lorentz contraction, specifically whether a truck measuring 5ft tall could pass under a 4ft barrier when moving at relativistic speeds. Participants explore the visual effects observed by a spectator and the truck's frame of reference.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions if a truck could pass under a barrier due to Lorentz contraction, asking about the visual perception of both the truck and the barrier from different frames of reference.
  • Another participant asserts that there is no contraction in the transverse direction, stating that the truck's height remains unchanged across reference frames.
  • A different participant reiterates that length contraction occurs only in the direction of motion, confirming that the truck's height would not change in the road frame.
  • One participant references the Thin Man and the Grid Paradox in relation to longitudinal contraction and its implications.

Areas of Agreement / Disagreement

Participants generally agree that the height of the truck does not change due to Lorentz contraction, but there is some debate regarding the implications of this on the scenario presented.

Contextual Notes

The discussion does not resolve the hypothetical scenario fully, as it remains focused on the implications of Lorentz contraction without reaching a consensus on the visual effects experienced by observers.

Who May Find This Useful

This discussion may be of interest to those exploring concepts in special relativity, particularly Lorentz contraction, and its implications in hypothetical scenarios.

P Brane
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Would it be possible for a truck, measuring 5ft tall when stationary, to pass under a 4ft barrier by accelerating towards the speed of light?

If so what would a spectator see if standing next to the barrier, would the spectator see the truck shrink? What would you see of the barrier from the trucks frame of reference, would the barrier seem to grow?

Sorry if my question appears unclear I couldn't think of another way to explain it. Thank you in advance for reading/attempting to answer the question.
 
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There is no contraction in the transverse direction, so a five-foot tall truck will remain five feet tall in all reference frames.

There is a longitudinal contraction, and the longitudinal version of this asks why the contracted truck does not fall into a pothole. This is called the Thin Man and the Grid Paradox. See here.
 
P Brane said:
Would it be possible for a truck, measuring 5ft tall when stationary, to pass under a 4ft barrier by accelerating towards the speed of light?
Length contracts only in the direction parallel to the motion, not perpendicular to it. The height of the truck would remain unchanged in the road frame.
 
Thank you, that helped a lot. Do I now need to close the thread?
 

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