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#5
02.05.19, 06:58
 Ich Moderator Registriert seit: 18.12.2011 Beiträge: 1.751
AW: Problem mit der Lösung des Flachheitsproblems

Aus Wikipedia:
Zitat:
 k may be taken to have units of length−2, in which case r has units of length and a(t) is unitless. k is then the Gaussian curvature of the space at the time when a(t) = 1. r is sometimes called the reduced circumference because it is equal to the measured circumference of a circle (at that value of r), centered at the origin, divided by 2π (like the r of Schwarzschild coordinates). Where appropriate, a(t) is often chosen to equal 1 in the present cosmological era, so that d Σ {\displaystyle \mathrm {d} \mathbf {\Sigma } } \mathrm{d}\mathbf{\Sigma} measures comoving distance. Alternatively, k may be taken to belong to the set {−1,0,+1} (for negative, zero, and positive curvature respectively). Then r is unitless and a(t) has units of length. When k = ±1, a(t) is the radius of curvature of the space, and may also be written R(t).
Wenn du mit k=1 arbeitest, dann ist k/a² die Krümmung, und die wird beliebig klein. Wenn da steht, die Krümmung werde gegen 0 getrieben, dann bezieht sich das auf k/a².