All Questions
6
questions
17
votes
1
answer
3k
views
Why do cosmologists assume that inflation began shortly after the Big Bang, rather than at the exact start?
Somehow, I have never come across an explanation of why cosmologists claim that the alleged inflation of the very early universe occurred not at the Big Bang, but very shortly afterwards (~10^-36 to ...
- 5,177
1
vote
1
answer
169
views
Do Einstein's ten field equations use 20 or 40 variables? (2 or 4 for each tensor equation?)
One site I came across says Einstein's 10 Field Equations use 20 variables, while another said 40.
There are four variables in spacetime - three for space and one for time, right?
But there are two ...
- 5,177
1
vote
0
answers
32
views
How can scientists deduce the number of types of neutrinos, or 'effective number', from Planck satellite data?
Is it related to the way they deduce the Hubble constant from Planck data?
Would more types of oscillating and mixing neutrinos mean faster or slower expansion of the universe?
Would a fourth mass ...
- 5,177
13
votes
4
answers
6k
views
How can a black hole have a charge, or be charged?
So-called 'hairless' black holes (no-hair theory, or theorem?) , which is what real black holes are, can be described by just three characteristics: Mass, spin, and charge.
It is easy enough to ...
- 5,177
2
votes
1
answer
849
views
What is the 'scale factor' equation for a dark-matter dominated universe?
The Friedmann equations can be solved exactly in presence of a perfect fluid with equation of state
$${\displaystyle p=w\rho c^{2}} \qquad p=w\rho c^2$$
where ${\displaystyle p}$ is the pressure, ${\...
- 5,177
-1
votes
2
answers
367
views
What covers the outside of the Universe? [closed]
Is the Universe a sphere with water or ice surrounding its' confinement? Are there any theories that imply the Universe being confined within a sphere of water/ice material?
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