Shoot yourself in the head, rendering the body unconscious, and while its still debatedly unclear what happens next. The anthropomorphized being of the afterlife is still grounded by our understanding on how "a human body works and reacts to the environment (seeing, walking, touching etc.)"
There is simpler than a brain, before brains there was a simpler brain fabric called a nerve net which we see in very simple multicelullar creatures, allowing them to sense the world and react towards it such as grasping at the presence of food.
The very first happiness treadmill.
The (may be unsettling) trope of life that applies in all life is the happiness treadmill: All life "moves" in a form of action or reaction towards its inner state, either moving towards pleasure and displeasure. The very first fully autonomous organism "designed" for simple pleasure and avoiding displeasure. I'm talking ofcourse about jellyfishes and nematodes.
A tiny brain consisted of only 302 neurons. These small clusters of neurons interact with different chemical in the environment and thus moves itself depending on its 'happiness treadmill' to either (good/pleasure = food) or (bad/displeasure = predator).
The theme still remains the same moving on through even more complex creatures and the abstraction of good and bad still ground the behavior of the creature.
However, a nematode can't learn "new things". It's experience about life is entrenched to its basic chemical reaction that its 302 neurons "already know", between good and bad. Continue existing by eating food as energy and avoid death by avoiding predators and keep moving towards possible source of food led by available chemical compounds on its surrounding.
I want you to pay attention towards on how these chemical reaciton is processed inside the nematode. On a strictly mathematical approach, it means as a function it takes an input in form of chemical signals and the function itself regulate those chemical signals as "meaningful actionable reactions" in forms of electric signals that moves the nematode muscle towards movement in a certain direction. It's a full circle biochemical and bioelectrical process being based by a "happiness treadmill." A neverending "Satiation" that will keep moving only until its biological body couldn't withheld its own body.
From nematodes, now we move on by 540 MILLION YEARS, the cambrian explosion. We began to see much more new animals marked by the fossil records. From capped neurons, newer living beings come to be observed with have more neural circuits.
Here's what we know, nematode could only experience the world with its limited senses. Other oganisms from the cambrian explosion can experience the world by processing even better sensory perceptions, with these new sensory perceptions, it needs to come bridged by newer and better electrical circuits to be processed later by the neurons for the organism to be able to act accordingly and appropiately from its better understanding about the world.
Mathemtically Sentient
I was supposed to write a lot of background introduction of the topic but I'm too unentertained to re-write some things I already know. I want to move forward writing this article by writing what I think may work and what I think is interesting.
If you are able to create a "thing" that is able to observe the world and plug it in a happiness treadmill, that alone itself, is what I think where sentience begins. Let's call the thing "Dave."
Coding the happiness treadmill is what I think should be the hardest. As much as we can observe spiders live to do its own thing, it has its own eyes, limbs, make silk, procreate etc. Coding the happiness treadmill is fucking absurd. When I think about it, now to create the more sentient creature, it needs a stronger sense of the happiness treadmill and with very strong consequences.
Existential demise is a creature's inability to play by the happiness treadmill and keep trying to seek something beyond the curtain, there's no inherent meaning, life is what you make of it, what you believe it to be, otherwise to believe what other people believe's life is about. I covered in great depths about this topic in the article, Context Dependent.
What I want to talk about here is that between biological and electrical beings (robots), there exists a very thin line, one of the key convincing statement is that: the way we function is still an over glorified electrical system encapsulated in chemistry.
From how our cells respond to stress using stress hormones and as our pupils dilated, its just an 'over-evolved' biological machine that come to understand the world tailored for its maximum chance of survival.
But let's talk actionable steps, I am somehow very motivated to prove religionists that we as humans are not some soul bearing multi dimensional creatures that is supposed to go to heaven or hell after we die, that for me is just a folklore, not much of a stronger folklore for the vikings to go to valhalla after they die.
There's multiple approach to this, to either build out of metals and wires or to understand how biological neurons and modify it.