Look at yourself. Right now.
You are muscle,skin, bone, brain, blood, warmed by energy, and all of you, every cell, even the subsets of those cells, all trillions and trillions of them, are going to tire, waste and depart. In 10 years almost every bit of you will have been replaced by new bits.
And yet, you will still be you. You will look like you do (sort of), you will behave like you do (sort of), others will know it's you (most of the time), and though a census of your innards will say, this is a new body, a different collection of atoms, you will know it's the same old you. How come?
If you are all new on the inside, how do you persist?
What Keeps Us Whole?
Well, there's your soul. If this weren't a sciencey blog, we could stop here. Your soul, breathed into you at your conception, will hang around till it's time to go and then be off to wherever it is souls go to. But suppose you are a "materialist"? Suppose you choose to imagine this journey naked, you as just a bunch of atoms, nothing added? What holds a soulless soul together?
The answer, these days, is your brain. Your memory. It's the story you tell yourself as you grow up, the unfurling narrative that begins with faces and smells and meals and sounds, then stretches into tales about your mom, dad, siblings, your pets, your family, your friends. It deepens with loves, joys, disappointments. It is always told by you, filtered through you. You are the one who tells it, you are the one who hears it, you are the only one who knows every bit of it.
Memories Are Our Duct Tape
To a significant degree, you are the sum of the stories you tell yourself about yourself.
Take away your memories, the connective tissue of your life, and what's left? You may be breathing, but in the late stages of memory loss, you aren't really there any more. You have unraveled.
We live this life together, but we experience it alone.
And when you actually die, what is annihilated? Well, there are tens of thousands of private images in your head right now: the pigeon you once almost caught when you were 4. The sight of a particularly beautiful girl disappearing through a doorway. The brief whoosh made by a snowy owl flying low that time you were walking alone in the woods. These are things no one knows, no one ever knew, no one but you.
When you go, they go. Forever. But as long as you're here, they stay. So, to all those pigeons, those girls, those owls that live in our heads, as long as we're here to all of you, and to us, Happy New Year!