How familiar are you with the field of very large numbers?
http://en.wikipedia.org/wiki/Large_numbers
Anyone can easily represent "one million" on paper, simply by writting out "1,000,000". It is only 7 digits with optional separaters for clarity. In everyday terms, that is a big number. With a million dollars, you could live your entire life in carefully measured comfort. Add a few more digits, and with a billion dollars you could do practically anything you wish for the rest of your life... and still have money to burn. Add a few more digits, and with a trillion dollars, you could make a significant global impact. 1,000,000,000,000 is still a very small number.
Ask a school child (or even most adults) what the largest number they can name is and most will say "a googol" or "a googolplex" (now often confused with the famous internet search engine, spelled differently). One million is 10
6. A googol is 10
100 (or 10
102). It is a one followed by 100 zeroes; a 101-digit number. You could again easily write this down on a sheet of paper, but it would be a bit tedious:
1 googol = 10
100 = 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
There are roughly 10
80 atoms in the Universe. That means you would need to count every atom in existence 100,000,000,000,000,000,000 (10
20) times over to reach 1 googol. That's a pretty big number, but you only need 101 digits to represent it.
But a googolplex is on another scale entirely. 1 googolplex is 10
googol (10
10100); it is a number with "a googol + 1" digits. You couldn't write out that many zeroes with all the paper on Earth.
As I said, there are only 10
80 atoms in the Universe. 10
100 digits and only 10
80 atoms to work with. See the problem?
Assuming each digit requires one byte to encode, a modern 1 TB hard drive would be filled with a single trillion-digit number (10
12 digits). That means that you would need a hundred million (10
8) of those hard drives for every atom in the Universe in order to store a googol zeroes. Yeah. Not possible. We can only reasonably represent it using exponents: 10
10100.
But even a googolplex is tiny when compared to other large numbers.
Take, for example, the Busy Beaver function.
http://en.wikipedia.org/wiki/Busy_beaver
The result of the Busy Beaver Σ function grows so fast, we've only been able to calculate a 2-symbol BB Σ(n) for n=1, n=2, n=3, and n=4.
BB Σ(1) = 1
BB Σ(2) = 4
BB Σ(3) = 6
BB Σ(4) = 13
Beyond that point, we've only been able to estimate very loose lower bounds for what the actual value is. We simply do not have the resources to calculate the actual values.
BB Σ(5) has been calculated to be at least 4098 and BB Σ(6) is at least 4.6 × 10
1439. They are likely much larger.
BB Σ(7) is said to be easily large enough to put googolplex to shame.
The result of BB Σ(8) is likewise said to be so large as to be physically impossible to represent at all, not with exponents, not even using Knuth's notation.
http://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation
So what happens when you get serious with this function?
How could we possibly work with a number like BB Σ(100)? Or BB Σ(googolplex)?
What happens when you start manipulating the function itself?
You could add to it: BB Σ(100) + 100
You could multiply by it: 100 x BB Σ(100)
You could use it as an exponent: 100
BB Σ(100)
Or, thinking bigger, you could exponentiate the function by itself: BB Σ(100)
BB Σ(100)
Or use Knuth's notation: BB Σ(100) "↑"↑"↑"↑ BB Σ(100)
Or even: BB Σ(100) ↑
BB Σ(100) BB Σ(100)
But even that's nothing compared to nesting the function within itself: BB Σ(BB Σ(100))
Using a greater number of symbols would also explode the values monstrously.
All of these can be easily written down, but represent numbers so large as to be completely meaningless. We have absolutely no practical need for such numbers. Yet no matter how high we go, we can easily go higher.
The concept of a "biggest number" is untenable and frankly absurd. There is no evidence to even suggest its existence. On the contrary, it is quite simple to disprove, as has already been done in this thread. It would, by definition, be at the end of the numberline, which would be like saying "0.000...1", which simply doesn't make sense and is a common troll theme.