Question about distance units in relativity

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SUMMARY

The discussion centers on the relationship between time and distance in the context of relativity, specifically using the equation ΔΤ2 = Δt2 - Δx2 - Δy2 - Δz2 with the speed of light (c) set to 1. It is established that when time (t) is measured in seconds, the units of spatial dimensions (x, y, z) must be in light-seconds, equivalent to 3x10^8 meters. The concept of natural units, particularly the common practice of setting c=1, is emphasized as a standard approach in theoretical physics.

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  • Understanding of proper time in relativity
  • Familiarity with the equation ΔΤ2 = Δt2 - Δx2 - Δy2 - Δz2
  • Knowledge of natural units in physics
  • Basic grasp of the speed of light and its implications in measurements
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  • Research the concept of natural units in physics
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This discussion is beneficial for physicists, students of relativity, and anyone interested in the mathematical foundations of theoretical physics, particularly those exploring the implications of unit systems in relativity.

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When one considers (proper time) ΔΤ2 = Δt2 - Δx2 - Δy2 - Δz2, with c = 1, if t is in seconds, are the units of x,y and z necessarily 3x108 meters?
 
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PerpStudent said:
When one considers (proper time) ΔΤ2 = Δt2 - Δx2 - Δy2 - Δz2, with c = 1, if t is in seconds, are the units of x,y and z necessarily 3x108 meters?
Yes. The unit of length is 1 light-second which makes c = 1.
 
Yes. You may find http://en.wikipedia.org/wiki/Natural_units interesting - there are several alternative systems of "natural units", but setting c=1 is most common. (There are also semi-joke "supernatural" units where pi=1, useful for interpretive dance physics, a.k.a "hand-waving".)
 

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