readingscalingpart 3

What Is a Power Law?

Scaling Laws, Made Simple · Part 3 · 6 min read

The scaling laws in the paper are all one kind of rule: the power law. In this blog, we will understand exactly what that is, using only small numbers.

Rules connect x and y

A rule takes an input x and produces an output y. Different rules have different shapes:

That last one is our first power law.

The definition

A power law is a rule where y equals x raised to some fixed power:

y = x^a

The fixed number a is called the exponent, and the exponent is the personality of the rule. Some examples:

The signature property: every 10x in x changes y by the same factor

Here is the one property that makes power laws special. Let’s discover it with y = x².

Look at what y does each time x jumps 10x: y goes 1 → 100 → 10,000 → 1,000,000. Every single 10x jump in x multiplies y by exactly 100. Not “roughly”. Exactly. And it does not matter where we start - from 1 or from a million, a 10x jump in x always multiplies y by 100.

This is the signature of every power law:

Multiply x by 10, and y gets multiplied by the same fixed factor - every time, at every scale.

That fixed factor is 10^a. For y = x², the factor is 10² = 100.

This is exactly why power laws can survive seven orders of magnitude. The rule treats every 10x jump identically. It has no built-in “natural size” where it starts or stops working. Compare that with rules that DO have a natural scale - a recipe has a natural size (a family), ant legs have a natural size (an ant). Power laws have none. They are scale-free.

Fractional and small exponents: slow-motion power laws

Exponents do not have to be big numbers like 2 or 3. The exponents in the scaling laws paper are tiny fractions like 0.076. What does a tiny exponent do?

A tiny exponent means y responds very sluggishly to x. Take y = x^0.076:

Ten million times more input, and the output didn’t even grow 4x. Tiny exponents make very lazy curves. Remember this laziness - it is why making language models better is so expensive.

Negative exponents: things that go DOWN

One more twist, and it is the most important one for us. The exponent can be negative:

y = x^(-a) which means y = 1 / x^a

A negative exponent means y goes down as x goes up. The signature property still holds, just downward: every 10x in x divides y by the same fixed factor.

Take y = x^(-0.076), which is the actual shape of the paper’s model-size law:

In the paper, x is the model size and y is the error score. So the law says: every time we make the model 10x bigger, the error drops by the same 16%. From a thousand parameters to a billion, each 10x jump buys the same percentage discount on error.

The same percentage - which is both good and cruel

Notice what “the same percentage each 10x” implies.

The good part: improvement never stops. There is no wall. Want a better model? Scale up. It always works.

The cruel part: each 10x costs 10 times more than the previous 10x. Going from 1M to 10M parameters is cheap. Going from 100M to 1B is a hundred times more expensive - and buys the same 16%. Every equal slice of improvement costs ten times more than the last slice.

This one sentence explains the last five years of AI: scaling always works, and scaling never gets cheaper.

Quick recap

Next: how do we see a power law in experimental data? For that we need one beautiful tool - the log-log plot.

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