Can we prove that the universe is finite or infinite?
56103
Is the universe finite or infinite?
149673
Cardinality of an infinite union of finite sets
127656
How to prove that if $A$ is infinite and $B$ is finite, then $|A\cup B|=|A|$?
41783
Cardinality of the Cartesian Product of Two Equinumerous Infinite Sets
4467
Proving Cantor's theorem
128437
How to prove that a finite set is countable
134071
If A is a finite set and B is an infinite set, then B\A is an infinite set
20680
Does infinity exist in physical systems?
2147
Different ways to prove there are infinitely many primes?
112910
Is the set of real numbers really uncountably infinite?
9651
Cardinality of cartesian product of an infinite set with N
100333
Show A is countable infinity
99478
countably infinite union of countably infinite sets is countable
81943
How to finish proof that $T$ has an infinite model?
120712
Is there a way to define the "size" of an infinite set that takes into account "intuitive" differences between sets?
95295
Is the Universe Past-Eternal?
78576
How to write “there exists an infinite number of”?