in the large picture,
• the size of a number
is proportional to
• how many numbers it can prove to be consistent.
the largest number proves the consistency of all numbers, including itself.
by Gödel's theorem, it is a "contradiction".
by Gödel's second incompleteness theorem, the axioms "finite numbers exist" can't prove their own consistency.
• Fin ⊬ Con(Fin)
now if we add "ℵ₀ exists", then we can prove the consistency of finite numbers.
• Fin + Inf ⊢ Con(Fin)
this shows Fin + Inf > Fin.
¹ this indicates "direct implications or relative consistency implications", tho.
(e.g., huge < supercompact)
in order of size and strength:
• inaccessible < measurable < huge < rank-into-rank < 0=1
infinities are written
• ℵ₀, ℵ₁, ℵ₂, …, ℵ_ω, …
in order from smallest to largest.
for the number of reals ℶ₁,
• ℶ₁ = ℵ_?
is not provable from the standard axioms of mathematics.¹
the ℶ₁ = ℵ₁ conjecture is called the
• continuum hypothesis (CH).
¹ already known to the Jains of India (400 BC), tho.
but they made mistakes such as the number of points on a line |ℝ| and a plane |ℝ²| are not equal. (both are 2^ℵ₀.)
actually, the number of natural, integer, and rational numbers are all the same.
that infinite number is called ℵ₀ (aleph zero) or ℶ₀ (beth zero).
Cantor (1874) proved that the number of reals is larger than that.¹
that is called 𝔠 = 2^ℵ₀ = ℶ₁ (beth one).
the idea that having the same number is the same as having a 1-1 correspondence is called
• Hume's principle.¹
¹ neither Hume nor Galileo thought it applied to ♾, tho (unlike Cantor).
have a look at this strange pic.
there's 2 circles.
a big one and a small one.
however, both circles consist of the same number of dots.
(there's a 1-1 correspondence.)
blog.wolframalpha.com/2010/0…
♾ is such a strange thing.
the whole and part can be the same size.¹
cf.
• Galileo's paradox.
¹ contrary to Euclid's 5th Common Notion (300 BC).
although some say that some CNs are by, e.g., Theon of Alexandria (4c).
mathematically, the answer is A✔
they're the same.
(even tho evens are part of integers.)
this is bc one integer corresponds to one even.
1 ↦ 2
2 ↦ 4
3 ↦ 6
4 ↦ 8
5 ↦ 10
︙
n ↦ 2n
︙
let me explain from scratch.
Q: which is greater,
• the number of all integers
• the number of all even numbers
both are infinite.
there's many ways to think abt it.
mathematicians consider infinity a number.
this is bc in the 19c, a man named Cantor found that there are "multiple infinities".
i.e., infinity 1, infinity 2, infinity 3, ….
just like 1, 2, 3, ….
can also do arithmetic with ♾.
The largest number is a "contradiction".
let me explain this.
u may be reminded of a googolplex or graham's number.
the problem is: graham's number+1 is larger.
they're still finite.