How Does the Singularity Behave as t Approaches 0 in the Kasner Solution?

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SUMMARY

The discussion focuses on the behavior of the singularity as time approaches zero in the Kasner solution of general relativity. Participants analyze the metric defined by ds² = c²dt² - X₁²(t)dx₁² - X₂²(t)dx₂² - X₃²(t)dx₃² and derive conditions on the exponents p₁, p₂, and p₃ from Einstein's equations. Key findings include that as t approaches 0, the scale factors behave such that two dimensions contract while one expands, leading to a singularity. The discussion concludes that not all p values can be positive, with the possibility of configurations like [1, 0, 0] or combinations of positive and negative values.

PREREQUISITES
  • Understanding of general relativity and Einstein's equations
  • Familiarity with the Kasner solution and its implications
  • Knowledge of metric tensors and their role in cosmology
  • Basic algebraic manipulation of equations involving exponents
NEXT STEPS
  • Research the implications of the Kasner solution in cosmological models
  • Study the Mixmaster cosmologies and their relation to the Kasner behavior
  • Explore the derivation of the Kasner solution from Einstein's equations
  • Investigate the properties of singularities in general relativity
USEFUL FOR

Students and researchers in theoretical physics, particularly those focusing on cosmology and general relativity, will benefit from this discussion. It is also relevant for anyone studying the dynamics of singularities in the context of the universe's evolution.

  • #31
I'll work on this, though I've been studying for 12 hours now. ;) If that's all I need to know then thanks for your help.
 
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  • #32
Take a break and good luck with the rest.
 
  • #33
I think I will need some help with the rest aswell. ;) No MatLab installed here...
 
  • #34
Unless I can use p_1p_2+p_2p_3+p_3p_1=0 aswell?
 
  • #35
Sure you can. It's a consequence of the other two relations between the p's.
 
  • #36
I get

p_1 = -\frac{p_3}{2} \pm \frac{1}{2} \sqrt{-3p_3^2+2p_3+1} + \frac{1}{2}

and

p_2 = \frac{1}{2} \left(-p_3 \pm \sqrt{-3p_3^2+3p_3+1} + 1 \right)

but what does this tell me? They cannot have the same sign but then what?
 
  • #37
Logarythmic said:
Unless I can use p_1p_2+p_2p_3+p_3p_1=0 aswell?

You are working way too hard. What does this say about the possibility that all of the p's are positive or all are negative?
 
  • #38
They cannot all be positive nor negative, but one positive and two negative or two positive and one negative. Is that right?
 
  • #39
Almost. Except you can't have two negative p's either.
p_1+p_2+p_3=1. What would this tell you about p3 if p1 and p2 are negative?
 
  • #40
Then p_3 > 1?
 
  • #41
You're catching on. But the sum of the squares should be one too!
 
  • #42
There we are. So it's either [1,0,0] or [+,+,-] and the behavior is strange. ;)
 
  • #43
Yes. If you want to see an attempt to use this strange behavior look up Mixmaster cosmologies sometime.
 
  • #44
Can you briefly tell me something about it?
 
  • #45
Sorry, better get to work here. Besides, other people tell the story better than I.
 
  • #46
I'll look it up tomorrow, now I need some sleep. Thanks for all your help.
 

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