What if--the universe is closed and very small?
3644
Symmetrical twin paradox in a closed universe
13096
Is a spontaneous decrease in entropy *impossible* or just extremely unlikely?
98769
Find a universe and a predicate that satisfy the following formula
113659
Why was the universe in an extraordinarily low-entropy state right after the big bang?
143493
Will gravity pull together two bodies from the other side of an empty universe?
44311
The Cracks in the Universe: Why are they lethal to some, but not to others?
75058
Why isn't an infinite, flat, nonexpanding universe filled with a uniform matter distribution a solution to Einstein's equation?
660
Is the empty space really empty?
20511
Is it possible to experimentally show that observable universe is much larger than ~93B ly?
39654
When they say that the universe cooled after the big bang, where did the heat go?
135755
Many-worlds: how often is the split how many are the universes? (And how do you model this mathematically.)
2377
Is the total energy of the universe zero?
72416
The universe appears to have a lower bound in the time dimension, why not an upper bound?
16877
Is there anything smaller than a quark?
50584
Parallel universes: are there an infinite amount of universes?
24445
How can an infinite universe expand?
116989
Has the universe we live in started as a black hole that is imploding?