Understanding Lorentz Factor & Proper Time Invariance

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SUMMARY

The discussion centers on the Lorentz factor and the concept of proper time invariance in the context of special relativity. Proper time, denoted as tau (τ), is established as an invariant quantity measured by a clock along its worldline, while time dilation varies between different reference frames. The Lorentz transformation equation, τ = (1 - v²/c²)¹/² × coordinate time, illustrates how proper time is related to coordinate time, emphasizing that proper time remains invariant despite its dependence on the relative velocity (v). The conversation clarifies that while time dilation is frame-dependent, proper time is universally invariant across all inertial frames.

PREREQUISITES
  • Understanding of Lorentz transformations in special relativity
  • Familiarity with the concepts of proper time and coordinate time
  • Knowledge of spacetime intervals and their invariance
  • Basic grasp of Minkowski geometry and its implications in physics
NEXT STEPS
  • Study the derivation of the Lorentz transformation equations
  • Explore the implications of proper time in different inertial frames
  • Learn about the relationship between time dilation and relative velocity
  • Investigate Minkowski diagrams and their use in visualizing spacetime events
USEFUL FOR

Students of physics, particularly those studying special relativity, educators explaining time dilation and proper time, and researchers exploring the implications of spacetime geometry in theoretical physics.

  • #31
vanhees71 said:
I'm always somewhat in doubt, whether Minkowski diagrams really help.
They really helped me. It was Minkowski diagrams and the concept of four-vectors that made relativity click for me.

I think different students are going to “get it” with different mental tools. So educators need to know and use all of them. Of course, it is ok to have a favorite one and it is ok for that favorite to be different from person to person
 
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  • #32
PeroK said:
...in a frame where the clock is moving it is measured to be time dilated.

Note that it's not correct to say that the proper time is dilated, because proper time is the length of the spacetime interval, which is frame invariant.

That is, perhaps, a subtle point.
imo is crucial for better understanding.
I find the part I underlined to be VERY well worded. Textbook quality imo. (only thing I can think of is including the spatial separation between measurement taken and the thing being measured. for example "is measured at a distance to be time dilated.")

I get that is very implicit as was mentioned there is relative motion. but feel it may help separate the concepts [proper / dilated time] a bit quicker for those new to them.
 
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  • #33
Dale said:
They really helped me. It was Minkowski diagrams and the concept of four-vectors that made relativity click for me.

I think different students are going to “get it” with different mental tools. So educators need to know and use all of them. Of course, it is ok to have a favorite one and it is ok for that favorite to be different from person to person
me too, though of course to a MUCH lesser understanding than you have. (you've explained lots to me years ago)
I found the simple light clock to be very helpful too, for me helped visualize / see it play out.

The Minkowski modeling gets into comparatively more abstracted presentation than the idealized clock imo, but of course is a math tool of sorts, the idealized light clock is just an imaginary thing that helps my simple mind figuratively see the "mechanics" of this "tiny bit" of spacetime physics.
 
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