Loss of simultaneity explained by classical physics

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SUMMARY

The discussion centers on the concept of simultaneity in classical physics and its implications for moving observers. Participants argue that loss of simultaneity can be explained without resorting to special relativity, emphasizing Lorentz's contributions. They illustrate this with examples involving distant stars and observers moving at high speeds, highlighting that simultaneity is frame-dependent. The conversation concludes that classical physics does not inherently lead to a loss of simultaneity, as both classical and relativistic frameworks provide distinct interpretations of 'now' for different observers.

PREREQUISITES
  • Understanding of Lorentz contraction and its implications in physics.
  • Familiarity with the concept of frame dependence in special relativity.
  • Knowledge of classical physics principles, including the finite speed of light.
  • Basic grasp of electromagnetic interactions and their role in particle behavior.
NEXT STEPS
  • Study Lorentz transformations and their applications in special relativity.
  • Explore the implications of simultaneity in different reference frames.
  • Investigate classical physics experiments that measure the speed of light, such as those by Fizeau and Foucault.
  • Examine thought experiments related to simultaneity, such as the moving ship scenario discussed in the forum.
USEFUL FOR

Students of physics, educators, and anyone interested in the foundational concepts of relativity and classical mechanics, particularly those exploring the nature of time and simultaneity in different frames of reference.

  • #31
granpa,

the ability to ignore the speed of the ship is part of relativity. we are assuming a purely classical universe for this thought experiment.
Even in Gallilean relativity, a state of rest cannot be distinguished from a state of uniform motion.
 
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  • #32
granpa said:
they would have seen a loss of simultaneity where there isn't any?

would a classical object moving through a classical universe experience a loss of simultaneity within its own body or not? its not clear what you are saying.

i believe it would.

Using classical assumptions, they probably would have predicted a loss of simultaneity within a moving body but they also would have have incorrectly predicted the speed of light is different for different observers.

I gave the example that in a Michelson Morley type experiment they would have predicted that a signal emmited from the centre of the two arms, when reflected off mirrors at the ends of the arms transverse and parallel to the motion of the apparatus, would not return simultaneously, whereas the experiment proved the the signals do return simultaneously. Hense "they would have seen a loss of simultaneity where there isn't any".
 
  • #33
Mentz114 said:
granpa,Even in Gallilean relativity, a state of rest cannot be distinguished from a state of uniform motion.
classically one has only to measure the speed of light to determine ones velocity.
 
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  • #34
kev said:
Using classical assumptions, they probably would have predicted a loss of simultaneity within a moving body but they also would have have incorrectly predicted the speed of light is different for different observers.

I gave the example that in a Michelson Morley type experiment they would have predicted that a signal emmited from the centre of the two arms, when reflected off mirrors at the ends of the arms transverse and parallel to the motion of the apparatus, would not return simultaneously, whereas the experiment proved the the signals do return simultaneously. Hense "they would have seen a loss of simultaneity where there isn't any".

all i am trying to say is that loss if simultaneity can be explained classically. time dilation and length contraction can't as far as i know.
 
  • #35
granpa said:
classically one has only to measure the speed of light to determine ones velocity.

On the incorrect classical assumption that the speed of light would be different for different observers they probably would have incorrectly concluded that "one has only to measure the speed of light to determine ones velocity".

Classical physics largely assumed a static absolute medium that light propagated in, so it would not have been surprising if they incorreectly predicted a notion of absolute motion. If they had taken Gallileo a bit more seriously when he said there is nothing that can be measured in the closed moving cabin of a ship that would indicate your motion or lack of motion they might have come up with relativity as we know it sooner.
 
  • #36
On the incorrect classical assumption that the speed of light would be different for different observers they probably would have incorrectly concluded


its not about what they would have concluded, its about what a hypothetical purely classical object in a hypothetical purely classical universe would do.
 

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