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wolfram
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Hi, just a quick question...in the Friedman equation, k takes a value of either 1,0,-1.
But why is it a constant?
Thanks you for your time!
But why is it a constant?
Thanks you for your time!
Well, there are a few ways to think about it. I'll do it by writing down the FRW metric.wolfram said:Hi, just a quick question...in the Friedman equation, k takes a value of either 1,0,-1.
But why is it a constant?
Thanks you for your time!
wolfram said:But why is it [[itex]k[/itex]] a constant?
Chronos said:More importantly, the value of 'k' is irrelvant unless you reject the entire equation! I don't think you can do that without assuming the burden of some seriously 'out there' theories.
wolfram said:Hi, just a quick question...in the Friedman equation, k takes a value of either 1,0,-1.
But why is it a constant?
Thanks you for your time!
The value of k, also known as the curvature parameter, is constant in the FRW (Friedmann-Robertson-Walker) model because it is assumed to be spatially homogeneous and isotropic. This means that the curvature of the universe is the same at any given time and in any direction.
The value of k determines the type of expansion of the universe in the FRW model. A positive value of k indicates a closed universe where the expansion will eventually stop and the universe will collapse. A negative value of k indicates an open universe where the expansion will continue indefinitely. A value of k equal to zero indicates a flat universe where the expansion will slow down but never stop.
There is strong observational evidence for the constant value of k in the FRW model. The cosmic microwave background radiation, which is the leftover heat from the Big Bang, has been measured to be nearly isotropic, supporting the assumption of spatial homogeneity. The observed distribution of galaxies also supports the idea of isotropy.
In the standard FRW model, the value of k is assumed to be constant over time. However, there are some alternative theories that allow for a varying value of k. These theories are still being studied and are not yet widely accepted in the scientific community.
The value of k plays a crucial role in determining the fate of the universe in the FRW model. As mentioned earlier, a positive value of k leads to a closed universe that will eventually collapse, while a negative value of k leads to an open universe that will continue to expand. A value of k equal to zero results in a flat universe with a slowing expansion but no eventual collapse or continued expansion.