What is real?

Have you ever had a dream, Neo, that you were so sure was real? What if you were unable to wake from that dream?
- Morpheus (The Matrix)

If you haven't watched The Matrix (1999), you really should.

It's about a post-apocalyptic world where Artificial Intelligence (smart machines) dominate the world and build a simulation called The Matrix. In it, humans are plugged in a fantasy computer generated world. They are unaware they're plugged in this dream world and live life normally as it was in the beginning of the 21th century (before AI).

In the film, humans are connected to super computers via cables plugged directly in their bodies which send electrical signals making them feel everything happening in The Matrix. 

The film goes further with the last human city standing, bugs in the system, viruses and revolution against the machines. But the main idea I want to focus on is the generated dream world.

Basically, the film had one thing right; what we see and feel everyday is nothing but the interpretation of the electrical signals being received by our brain.

Let's assume your mother is baking a cake. Particles are entering you nose and your brain is interpreting the signal sent by your nose as cake. You are tasting it, your tongue is touching the cake and sending your brain a signal, your brain again receiving a signal that it's delicious and tastes like chocolate.

(To be more accurate, it's trillions of neurons in your brain cooperating to interpret a very complex signal, but let's simplify for a moment and assume it's a simple signal interpreted by one neuron and we'll generalize later). 

If we have a monitor between the nose and the brain, we can use it to record the signal  being sent by your nose, and we'll be able to recreate it. Same with the other senses.

Now let's assume we can access all the neurons in the brain via very tiny cables, so we can send signals to each one. Assume we also know which is responsible for each sense.

Do you see it all coming together? We have the recorded signals, and we have access to the brain's neurons.


Let's send - to the brain - one signal we recorded earlier; the taste signal. Normally, your brain will interpret it as chocolate cake as if you were tasting it for real.

Let's take it further and send 2 signals simultaneously, the taste signal and another one we recorded earlier; the smell of chocolate. Now you are more convinced it's happening because your brain is making you smell it and taste it. 
This where it gets interesting, let's dare and send more signals simultaneously. The two signals of smell and taste, add to it one for sight accompanied by sound signal and even another one for feeling cake in your hands.

The sent signals are acting as a video signal you recorded earlier of seeing /holding /eating and even hearing your self eating a chocolate cake being sent to your brain. 

Now you are officially in a "real" dream. Your brain is making you think it is happening without it really happening.

Is this so hard to believe? There are so many people with delusional disorders who can't tell what is real and what is not. These people are not faking it, they see and hear things that aren't happening.

Of course in this case, nobody is synthesizing signals and sending them to their brain on purpose, it's a brain disorder. But just to prove that it exists and feels real to them.

(For more details about delusional disorders - link)
It even happens to healthy people everyday. You may not imagine whole scenarios, but haven't you ever looked in a side direction quickly and thought you saw your friend but when looked again realized it's just your mind playing tricks on you?

Just like computers sometimes mistakenly interpret faulty signals, your brain had a minor glitch but it was for a millisecond so no harm done.

Let's get back to synthesizing brain signals.

We are making some hard assumptions, for it to work we are assuming we already have:

  • A powerful enough monitor to locate and record the most complex brain signals 

  • A powerful enough computer to analyze signals (if it's powerful enough it might be able to distinguish between signals and create new ones)

  • Access to all brain's neurons and understanding the function of each one

Which we don't, for now.

A lot of research is being done today on understanding the brain and it's signals.

Let's be optimistic and assume we'll have all the tools in the future, in the year 3021 to be exact (scientists have a thousand years to come up with solutions, no rush). 

Jump to the year 3021, we have all the tools to generate a dream world. A super computer connected to your brain which sends trillions of signals and generates whole scenarios. It's even powerful enough to run for a long time.

You can see, smell, taste, feel, hear everything the computer generates, and it's powerful enough to keep running and simulate a whole life from age zero.

Now picture this scenario: You are born, someone plugs you in the computer and sets the simulation to run a dream world similar to how things in the world were in the year 2021.

How do you know you're not in that simulation right now?