**Graham’s Number – literally big enough to collapse your head into a black hole**

Graham’s Number is a number so big that it would *literally* collapse your head into a black hole were you fully able to comprehend it. And that’s not hyperbole – the informational content of Graham’s Number is so astronomically large that it exceeds the maximum amount of entropy that could be stored in a brain sized piece of space – i.e. a black hole would form prior to fully processing all the data content. This is a great introduction to notation for *really* big numbers. Numberphile have produced a fantastic video on the topic:

Graham’s Number makes use of Kuth’s up arrow notation (explanation from wikipedia:)

In the series of hyper-operations we have

1) Multiplication:

For example,

2) Exponentiation:

For example,

3) Tetration:

For example,

- etc.

4) Pentation:

and so on.

Examples:

Which clearly can lead to some absolutely huge numbers very quickly. Graham’s Number – which was arrived at mathematically as an upper bound for a problem relating to vertices on hypercubes is (explanation from Wikipedia)

where the number of *arrows* in each layer, starting at the top layer, is specified by the value of the next layer below it; that is,

and where a superscript on an up-arrow indicates how many arrows are there. In other words, *G* is calculated in 64 steps: the first step is to calculate *g*_{1} with four up-arrows between 3s; the second step is to calculate *g*_{2} with *g*_{1} up-arrows between 3s; the third step is to calculate *g*_{3} with *g*_{2} up-arrows between 3s; and so on, until finally calculating *G* = *g*_{64} with *g*_{63} up-arrows between 3s.

So a number so big it can’t be fully processed by the human brain. This raises some interesting questions about maths and knowledge – Graham’s Number is an example of a number that exists but is beyond full human comprehension – it therefore is an example of a upper bound of human knowledge. Therefore will there always be things in the Universe which are beyond full human understanding? Or can mathematics provide a shortcut to knowledge that would otherwise be inaccessible?

If you enjoyed this post you might also like:

How Are Prime Numbers Distributed? Twin Primes Conjecture – a discussion about the amazing world of prime numbers.

Wau: The Most Amazing Number in the World? – a post which looks at the amazing properties of Wau

**IB Maths Revision**

I’d strongly recommend starting your revision of topics from Y12 – certainly if you want to target a top grade in Y13. My favourite revision site is Revision Village – which has a huge amount of great resources – questions graded by level, full video solutions, practice tests, and even exam predictions. Standard Level students and Higher Level students have their own revision areas. Have a look!

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July 23, 2015 at 6:59 pm

LiopleurodonWhen you say that Graham’s number is so astronomically large that to input it into the human brain exceeds the amount of entropy(or bits of information) possible in a human brain, are you referring to a bit as in planck length squared? But could you also argue that before you reached that point(say you had infinite time) your brain would have filled up its total storage capacity due to neuron connections?

July 23, 2015 at 7:05 pm

Liopleurodonhttps://en.wikipedia.org/wiki/Bekenstein_bound Is it on the lines of this?

November 25, 2017 at 8:39 am

TIL about Graham's Number, a number so large that any attempt to explain its size will be a vast understatement. » Best content from the Internet[…] View Reddit by aretheyaliens – View Source […]

December 28, 2017 at 4:24 pm

Graham’s Number – The Abstract Unknown[…] References: https://waitbutwhy.com/2014/11/1000000-grahams-number.html https://en.wikipedia.org/wiki/Graham%27s_number https://blogs.scientificamerican.com/roots-of-unity/grahame28099s-number-is-too-big-for-me-to-tell-you-how-big-it-is/ https://www.youtube.com/watch?v=XTeJ64KD5cg https://www.youtube.com/watch?v=HX8bihEe3nA https://www.youtube.com/watch?annotation_id=annotation_2349383243&feature=iv&src_vid=HX8bihEe3nA&v=GuigptwlVHo https://www.youtube.com/watch?v=rGWuimr5CGQ https://ibmathsresources.com/2013/04/15/grahams-number-literally-big-enough-to-collapse-your-head-in… […]