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Figure 1: Physical and perceptual (neurological) emergence |
Almost everything we see and interact
with around us is emergent.
That is, things we think of as objects
are actually made up of many small particles.
These objects are also actually a
story we tell ourselves, icons in our mind, which, from the point of view of
the constituent particles, do not exist.
To give an example, imagine a rigid blue cube:
That cube is made up of many molecules
which stick together, and when stuck together have certain rigid properties and
a cubic shape. Light hitting the cube is absorbed,
except for a particular range of wavelengths we call 'blue'.
We can then call these 'blue' and 'cube' characteristics - macroscopic observables of the thing we
call a blue cube. (From Greek, makros 'μακρός' means large and skopein 'σκοπεῖν' means
look at or observe, as in 'telescope'.)
But that's not all there is to it!
That was the physics side, the construction of the physical entity.
However, it would not be a cube if we
had never observed it. That is, imagine a planet in a far-off galaxy, with a
rigid blue object, or imagine humans had never existed. Until humans exist and
observe that object, it does not even become an object, much less a 'blue cube'. In fact, until we observe this particular collection of
molecules, what's really to separate it from the rest of the planet, or to
separate the 'planet' from the space around it. All of this objectifying is
human choices.
Now we enter the picture. We reach out
our hand, we grab this collection of molecules, and we look at it. Our visual
and neurological system responds to our sensory input (vision, touch) and these
signals travel up our neurons into our brains, vast networks of neurons.
Our neuronal networks fire in
patterns, aggregating the visual information from individual neurons in our
retinas and hands, and compare it to past input patterns we have observed, as
well as written or verbal inputs we have associated with those patterns.
Our neuronal network, through this
process of aggregation, also reaches a macrostate of firing patterns, and does
what we call 'decides' (represents) that the current input patterns closely match those past
patterns, and yields the associated verbal and written patterns, which are 'blue cube'.
So isn't that interesting?! In order to
create a representation of a 'blue cube', we had two emergent
processes [Fig. 1].
First, physically, the molecules had to come
together into a macroscopic object, then our neuronal system had to aggregate
many individual neuronal inputs to internally create a macroscopic
representation in the brain.
We can do some thought experiments to
understand this better. Let's suppose we reading this are like the audience in
a movie. We can observe the physical situation, but also the brain of a human astronaut
who lands on the planet of the 'cube':
Let's look at each thought experiment
from the physical and neuronal point of view:
- Imagine our astronaut lands on the
planet and just sees a patch of blue smeared on the surface.
- Physical: This isn't even an object, much less some separate
macroscopic entity resembling a cube.
- Neuronal: This pattern of inputs doesn't match what we typically call
a 'blue cube'.
- How about some holographic image
projected onto a cloud of gas which we moviegoers can see looks like a blue cube?
- Physical: Hmm, ok, this is again emergence of a collection of light
rays that create some kind of macroscopic object. However we moviegoers can clearly say that this is not a physical cube.
- Neuronal: Our astronaut's visual system aggregates the information and
decides it's a blue cube. However, then the astronaut reaches out to
grab it, and his or her glove passes through it. When this new touch sensory information is
aggregated with the visual, the astronaut's neuronal system maps this to a different
internal representation ('an optical illusion of a blue cube').
- What about this?: A hyper-intelligent
organism which can project wavelengths of light in different directions, and
change its form from rigid to soft, etc. Or what if it can do this so quickly,
much more quickly than a neuron can fire, so that it is changing form and
emitted light so quickly that the astronaut doesn't observe it. What if 99% of the time, it
emits the red wavelength of light and is actually as soft as jello, but not
when the astronaut's nerves sense it.
- Physical: We moviegoers can see that these are very different
collections of atoms or molecules. From our point of view, we might not call
these collections blue cubes at all.
- Neuronal: Our astronaut's neuronal input continues to match 'blue cube'. When the astronaut's neurons receive visual input, they happen to
always be the blue of the blue cube. The astronaut's neurons receiving
touch input, when it is aggregated in the brain, matches patterns of rigidity
and cubic shape.
We could go on like this for some
time, coming up with creative examples that we moviegoers would not call blue cubes, but which fool the astronaut.
We could probably come up with
examples which physically are blue cubes, but our astronaut's brain
thinks are not. For example, case number 3 where the cube is blue and rigid
99.999% of the time, but not when the astronaut's neurons sense it! Or if the
sun gives off a strong red light, making the cube appear black, etc. etc.
So, what exactly is emergence? Let's
do some more thought experiments...
Let's go back to the physical blue cube.
How many different materials can we
make a blue cube from? There are many
materials that are rigid.
Let's make some simplifying
assumptions (it will occur to us why these are simplifying, but they don't
matter much for our experiments).
Suppose there are 20 different
molecules (substances) that are rigid and do not absorb the blue wavelength of
light, so they appear blue. So then for each molecule of the 'cube', we have 20 choices.
Now, just for a moment, let's suppose
our cube is made only of 2 molecules (a very tiny cube). So, for the 1st molecule
we have 20 choices, and for the second molecule, we have 20 choices. So we have
20 * 20 or 20^2 = 400 ways to make a blue cube!
Now let's make a larger blue
cube. Let's suppose it has approximately 4.27 x 10^27 molecules, physically a more realistic number. With that many
molecules, there are 20^(4.27 x 10^27) ways to make a blue cube.
This is a HUGE number, so big that it has
1.30103×10^27 decimal digits just to write it down!!!
When we zoom out, all of these versions of the cube appear
the same, so an observer would call all of these ways to put together these molecules
the same blue cube!!
In physics, each of those ways of
making the blue cube are called 'microstates'. They are particular
instances of choices of each particle or element that make up a system.
Usually, the number of microstates is huge, since most objects around us are
made of a very large number of molecules.
We can call the blue cube
itself --which looks the same to us moviegoers no matter how we choose the
molecules-- the macrostate, which always has the same macroscopic observables
(large-scale appearance).
Now, let's go back to our Astronaut's
neurons and brain.
The astronaut sees this collection,
this clump of rigid blue molecules -- many individual neurons in the retina
respond to a collection of blue light input in a cubic pattern.
This information travels up into the
brain to be aggregated, where other neurons are stimulated when neighboring
retinal neurons give similar input, until it is encoded (represented) in a pattern
corresponding to 'blue cube' in semantic and linguistic neuronal representations.
Notice that, in the brain, we could
argue that until the semantic or linguistic representation of 'blue cube' is activated, there is no
blue cube. (However it is
represented doesn't matter here.)
Let's again make some very simplifying
assumptions:
Suppose the light from the blue cube stimulates only 2 neurons in the retina, and each of these neurons
can be in state blue, green, or red (3 states). There are then 3 x 3 = 3^2 = 9
ways these neurons can be activated. Notice that each of these ways are again
microstates.
Notice that we only call one of these
ways --when both neurons are in state 'blue'-- the 'blue cube'. This is
again the macrostate, the large-scale description of the system.
Suppose instead that the light from
the blue cube stimulates 1000 neurons in the retina, and that each of
these neurons can again have 3 states. This is now 3^1000 or 1.32 x 10^477,
another extremely large number! (This is probably a very small estimate since
the retina has approximately 100 million neurons!)
So again, out of those different ways
of stimulating 1000 neurons, we probably have a few choices. If there were a
small number of green or red tiny dots, we might not notice them, and the
astronaut might still call the cube 'blue'. But that number of ways of having
dots on the blue cube is probably small compared to 10^477.
Even if there are 10^100 ways to have
a few green or red dots, these slightly dotted ways of having blue cubes are
only
(10^100)/(10^477)
=
1/100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
of the ways to have a solid clump of
neurons stimulated by only blue light!
This is so small, let's disregard these dotted ways! We could say something similar about rotating the cube. Yes, there are many ways to rotate, but these are again very small compared to ways of seeing a solid block of blue.
So out of all of the 1000-neuron
images the astronaut could see, roughly only 1 of them looks like a blue cube,
the solid geometric clump of blue. This is again the macrostate.
This macrostate emerges from the
number of ways of obtaining it, the microstates.
In fact, when we reflect on it, the macrostate is forced upon us, stepping unstoppably out of the vast space of possible collections of molecules.
Now, let's take a look around us.
Everything we see, everything we think of as an object, has both of these
types of emergence going on, the physical and the perception through our
neurological system.
That is, although 'clumps' of
molecules or other objects exist, physical macrostates, until we perceive them, they do not exist for
us. So both the physical and perceptual emergence must occur for these objects to exist for us.
We can use a similar way of thinking
to see that the number of ways of obtaining almost any 'macroscopic' (large scale)
object around us is extremely large, but it is very small compared to all the
arrangements of molecules.
For example, there are many ways to arrange carbon,
calcium, hydrogen, oxygen etc. atoms to have a 'hand', but there are vastly many
more ways to arrange those atoms which we would not call a 'hand' from a
physical perspective (for example, a block of carbon, a block of calcium, and a
puddle of water).
On the neurological side, there are
many patterns of light which, falling on the retina, would stimulate the
neurons and brain in a way resulting in a semantic representation 'hand'.
However, there are again vastly vastly more ways of stimulating those same
neurons which would not activate semantic representations of 'hand', and
instead would be represented by some other macrostate (e.g., blocks of white
stuff, black stuff, and a puddle).
Perhaps it is interesting to carry out
similar thought experiments for yourself, and think about other examples in
physical or perceptual emergence, or a combination of the two:
- How many ways physically can we have an
object that looks like a cube only on the outside?
- Why do we choose to say that a blue cube is an object?
- Why not interpret part of the corner of the cube and a triangular chunk of the table (etc.) as one object?
- Do the micro- and macro- states in our brain correspond to the physical micro- and macro-states?
-
How to improve the estimates above?
-
Why do we need a sense of touch?
- Can we measure the effectiveness of our senses by their reduction of possible microstates of the world around us?
-
How this relates to
misunderstandings in communication?
-
How this relates to optical
illusions?
- Magic tricks?
- Stories? (how many plausible stories - or just plots - are there?)
-
How much information is our brain processing just looking at the room around us?
- Can we even estimate this?
- How about when we walk around the room?
- Drive a car?
If you find this interesting, you can learn more!
Check this blog in future for more on complexity, mathematics and other recreations!
Here are some books and links to the field of complexity science, also known as complex systems:
Complexity Science: The Study of Emergence by Henrik Jeldtoft Jensen
Complexity: A Guided Tour by Melanie Mitchell
Complexity and Criticality by Kim Christensen and Nicholas Moloney
Wikipedia: Complex Systems