I like to propose to people that we calculate in our heads two year's growth on 100£ at 1% per year. We get 1£ the first year, and another 1£ and a pence the second year - for a total of 102.01£.
When I decided to write down the exercise just described, I could not stop at two years and wrote down the table immediately below. After the row that has only 100 in it, each row contains the exact theoretical growth/interest for one compounding. However, I no longer want to think of the numbers as representing money. And the compoundings need not represent years. My purpose below is to look at the mathematical properties of this kind of rolled over growth - regardless of what is growing. After the column that has only 100 in it, each column contains growth amounts for the previous column and from previous rows. In the third compounding, we have 1 from the 100,   and we have .02 from the two previous 1's, and .0001 from the previous .01 and so on. The factors apply to the numbers below the 'factor' row, and I think this makes clear the meaning of this scientific notation for small numbers - where the power of ten has a minus sign: There is an implicit decimal point after each number in the last row, and we move that decimal point to the left by the number of places indicated by the power of ten, and pad with zeros.
At this point, I would like to point out
(1) that modern humans are about 100,000 years old, and
(2) that tool making has been going on for about 2,000,000 years.
With 100,000 compoundings,
the first two columns sum to the first two numbers below,
and all the rest of the columns sum to the third number.
Anyone who needs to contemplate the national debt of the USA should be comfortable with scientific notation.
If we have all the digits, we move the dicimal point 434 places to the right.
But we only need the first one or two digits to say that the number is larger than the 434th power of ten,
which is a one followed by 434 zeros.
The number below is the integer part of the sum of all columns beyond the second.
The fractional part is a little more than one half.
The digits have been arranged so that it is easy to see that there are 434 after the initial 1.
To appreciate how big the next number is,
multiply the mass of the earth by 16 and two-thirds, and then
imagine how much more massive that is than one cubic meter of water.
A 1 with 100 zeros is called a googol ...
And now we go back to my little bit smaller large number ...
... and the known universe as a multiple of the hydrogen atom is to the 135th power of ten
as a cubic meter of water is
to 16 and two-thirds times the earth!
Universe busting is the name I like to call numbers this size or larger.
Since the "universe busting" explosion occurs in "all the other columns"
it seemed a good idea to look at when all the other columns surpass the first two.
I have a friend who argues for the reimposition of usury limits.
Based on these figures, I would suggest that the limit should be 2%.
I wanted to look at what the impact might be on sustainability
if we truncate the interest to the first two columns
The impact of truncation seems encouraging for high growth rates, such as 20%:
Here are some usefull scientific notation representations for some American big and small number names.
Here is where my little bit smaller large number came from.
This grows an American (trillionth of a trillionth of a trillionth) of a hundredth
at one basis point per year
for 4,000,000 years.
And here is what we get at ten basis points for 2,000,000 years.
BUT AGAIN (with the American number names):
Truncation to the first two columns seems to radically improve sustainability.
Finally, I have included last what started out as my first frame. How would it be if our lungs worked like our economies? We would not be able to exhale without excruciating pain! And if our economies worked like our lungs? That's how it should be. And sometimes I think today's experts are like medieval mechanical engineers. Things are set up so that abject misery and failure follow in the absence of a perpetual motion (growth) machine, and they are classically striving to build such a machine - oblivious to the fact that it is classically impossible. "And that's all I have to say about that." - Forest Gump.