All Questions
32
questions with no upvoted or accepted answers
2
votes
0
answers
85
views
Could the universe be a 4-ball?
I recently thought of the idea that the universe could be an infinite 4-ball. The Big Bang would be its centre, and time would be outward from its centre (one layer would be one point in time). I ...
user334229
2
votes
1
answer
369
views
Does visible universe have shape of a 3-sphere?
Here's my logic:
If you look out in the visible universe you see further back in time. Look enough back and you get to the big bang singularity.
This means whichever way you look in the visible ...
user84158
2
votes
1
answer
174
views
Is there any way to tell if the Big Bang happened everywhere or just in some regions of the entire universe?
On large scales, matter seems to spread uniformly in our observable universe so we think the Big Bang happened everywhere in the observable universe.
Is there any way to tell if the Big Bang happened ...
- 455
2
votes
2
answers
93
views
Universe expansion from initial explosion
If the universe is expanding at an accelerated rate, is it because it hasn't reached its maximum velocity from initially exploding?
I'm thinking in terms of a bullet being fired from a weapon. It ...
- 71
2
votes
1
answer
388
views
What arguments are in favour of an atomic structure to space-time?
The atomic theory as first theorised by Democritus has been successfully applied to matter and to energy (quanta).
Space-time is still generally seen as a continuum. What arguments are there (if any) ...
- 13.1k
1
vote
0
answers
60
views
Is the universe closed or flat?
Apparently there is a tension in the measuring of the curvature of the universe (https://arxiv.org/abs/2307.07475) as apparently in 2018 the Planck collaboration got a series of results consistent ...
- 2,462
1
vote
1
answer
102
views
If spacetime is discrete, would we observe continuous models to show non-rounding and non-truncation errors?
Typically, the ground truth is taken to be the continuous model. Numerical simulations are taken to be the approximation. These simulations deviate from the continuous model due to both a constant ...
- 870
1
vote
0
answers
51
views
Can a cosmological constant model inhomogeneities?
Consider the following zero-order approximation to the universe:
Spacetime is perfectly homogeneous, and
The cosmological constant is exactly zero.
This doesn't quite work. Neither assumption is ...
1
vote
0
answers
286
views
Is the universe a lattice?
My understanding is that cause and effect create a partial order of events in the universe (and that relatively prevents anything stronger).
My understanding is also that it’s generally useless to ...
- 111
1
vote
1
answer
179
views
How does the scale of homogeneity and isotropy of the universe change as we go back in time?
This question is an upshot of a previous question asked by me.
The FRW metric of the Universe is based on homogeneity and isotropy of the universe on a length scale of 100 Mpc or larger. If we go ...
- 26.8k
1
vote
1
answer
471
views
What is meant by "spontaneous creation" in this paper?
I have some questions in regard to the paper "Spontaneous creation of the universe from nothing". If I am not mistaken it is akin to Alexander Vilenkin's proposed cosmological model that has the ...
- 11
1
vote
0
answers
79
views
The expansion of the universe and its edge
I have understood that the universe is expanding at an accelerated rate. I have also thought, perhaps mistakenly, that this expansion means not that the masses in the universe are moving away from ...
user123987
1
vote
0
answers
485
views
What evidence is there of a universe older than 13.8 billion years
I've read an analogy that finding iron-rich galaxies just 900 years after the Big Bang is like finding an old man in a crib in a nursery. We just recently found a supermassive black hole 12 billion ...
user32023
1
vote
0
answers
132
views
A model that predicts the universe is finite in space and time
A physics professor talked in the YouTube video Cosmological Constant & The End of the Universe - Sixty Symbols about a paper he and his colleagues published. The paper presents a model that ties ...
- 719
1
vote
0
answers
220
views
Can universe be a closed manifold?
I had a question at MSE which gave a rise to another question.
Maxwell equations can be written in form $$d\star F = J$$
Then by Stokes theorem we have
$$ \int_U J = \int_U d \star F = \int_{\...
- 748