Topic: If 98% of the atoms in our body are replaced in just 1 year, what are we? (Read 5718 times)

More than likely, close to 100% of the subatomic particles that make up the protons, neutrons, and electrons in our bodies, are constantly replace and converted, almost instantaneously every second, as the parallel universes that create them roll past each other.

What, really, are we?

Cloning is one of the last problems of scientific development. The most fundamental limitation is the impossibility of a repetition of consciousness, it can not be a complete identity of individuals, as shown in some movies, but only about a conditional identity whose measure and boundary is still to be investigated.

Every new year, I become a new man. True story

I disregarded any metaphysical considerations because of this: https://bitcointalksearch.org/topic/why-im-an-atheist-1424793

What that tells me is that we cannot define ourselves completely by what we see and can measure, to me that tells me that whatever makes us a unique individual is not tied to the physical reality we can measure.

Beside theories that argue for eternal inflation, infinite Universes or that our Universe is infinite, also theories that argue that our Universe is going forever to explode on a Big Bang and then return on a Big Crunch (Big Bounce: https://en.wikipedia.org/wiki/Big_Bounce) are compatible with the idea that there will be more universes exactly like ours or that there are already Universes like ours with another us.

In short, every cosmological theory that argue that the creation of matter is eternal are compatible with the idea that soon or later there will be exact copies of us.

On my post about atheism (https://bitcointalksearch.org/topic/why-im-an-atheist-1424793), I wrote that we were nothing for an eternity and will be again nothing for another eternity after our death.

However, if we accept that the quantum fields (see https://bitcointalksearch.org/topic/m.14388816) that created all the stuff (matter, energy) and this universe are eternal and will keep creating stuff forever (search A Universe from nothing), like supposedly they did in an eternal past, then, after almost an eternity, they will create another universe exactly like ours, with an Earth like this and with you and me, writing again on this forum.

Actually, in the past, there must have been many of you and me.

At least if we accept that what is me and you isn't an exact body (like explained on this OP), made of some specific atoms, but a pattern of organization of them (a DNA and the particular synapses of your brain).

Some argue that there are infinite universes, constantly popping out from new Big Bangs (search for Eternal Inflation) and, therefore, there must be a universe like this one, with another you and me. But this theory is very controversial, much more than the idea that the quantum fields are eternal.

Anyway, some argue that there might be other yous and mes living a different life. However, that would be much harder to happen.

We were the result of a specific egg and spermatozoid. Any difference on our universe past and we wouldn't exist. It would be enough a few different seconds on the life of one of our billions (including non human ancestors) of ancestors to a different child to born, changing necessarily all our ancestors chain.

For us to be living a different life would be necessary that all the past of a copy of our universe to be exactly the same of this one up to us and then we would change something in our life.

For us to be born again, it will be necessary an universe exactly like this one since the beginning, 14 billion years ago, with the same exact mass down to the quark, created out of chance.

How likely is this to happen? After death, at best, we'll be nothing again for a zillion of trillions of years... but after this long, we'll live again, without the conscience of the lots of me and you that lived before.

But, at least, we'll live again and again and again. After all, it seems we are eternal!!

We'll just have to wait almost an eternity between each life.

I prefer this one: https://www.youtube.com/watch?v=17WiQ_tNld4

I agree with you, some part of ours changes maybe everyday.  It maybe not that obvious but something changes.  Like of course we know that we aged and we become weak.  It is true because if there is no change then we still all are babies until now.   But seriously, everything grows on us our hair, our nails, we have changed our skin like that it is just slow process.  It is timely and well planned.

There is a video from CrashCourse on that theme.

I believe it's one of these:

https://www.youtube.com/watch?v=GxM9BZeRrUI

https://www.youtube.com/watch?v=3SJROTXnmus

No argument from me on that. But we are just clones of ourselves and that is a subject worth thinking about.

About the nature and composition of electrons we have nothing more than theories.

Anyway, without a link to a credible source (sorry, not the good book), your post is just words.

We will still be ourselves.  Because the one being replaced is just the same amount and same thing.  God is so great, he knew everything.  He knows how much hair we have, how much atoms it is needed to make us.  So even if the atoms in our body will be replaced in just a year we will still be the same.  And I do not think that it will not happened as everything in us is not an accident.

Electrons are aether eddys. They ALL change every nanosecond. You folks are so behind the times.

Identity = your unique brain neuron configuration + your unique genetic material.

Why is it so hard to comprehend?

As cells die, they are expelled from our body (so, their atoms are expelled). New cells are made from matter (atoms) that we incorporate (oxygen we breathe, food we eat, liquids we drink).

Even the neurons' atoms are replaced as they repair themselves. Probably, by expelling old molecules and creating new ones.

By this process, all our atoms seem to be replaced by new atoms of the same type.

We are just natural clones of ourselves.

Unique configuration of neuron synapses in the brain.

In the end, we are made basically of quarks (base of the protons and neutrons which form the atom's nucleus) and electrons.

As far as specialists know, both quarks and electrons are elementary/fundamental particles, made of "pure energy" (perhaps, composed by the famous strings). All its mass is created by the Higgs field because of the way they interact with Higgs Bosom.

These kind of particles have been compared not to a violin, but to the sound/vibration that the violin makes.

That seems what we are: a specific pattern of organization of energy.

But this is the easy part.

Things only start to be really bizarre when we think about what these particles that are part of our body can do according to quantum mechanics.

If the subatomic particles of my (temporarily) atoms can be at different places at the same time, am I also (of course, not conscientiously) at different places at the same time?

using knowledge of physics, biology and latest neuroscience, i would say we are just a dance. the thing we call "self" is just a convenient fiction.
a pattern from the very complex chemical soup that is the human body.

I already answered to you about that issue here: https://bitcointalksearch.org/topic/m.15070414

But I'm going to repost the full justification that I posted here: https://oneskeptic.tumblr.com/post/146726224082/on-death


"Since there can’t be any immortality, and death is our destiny, unfortunately, the issue of the effect of immortality on the value of time can’t be really tested.

Clearly, being able to live thousand of years would lower the value of our time. But I surely wouldn’t mind to have time to be able to real waste it.

You could tell yourself that you would be ready to die, after having a meaningful life. But that is just rubbish.

Or write, like Mark Twain, that death is as just natural as life, implying that we have to accept it as we accept life.

But this is also absurd. Death is natural, but it’s the end of life.

Let’s deal with death with a laugh, but saying that it must be a pleasant one is nonsense or proper of people that don’t give enough value to their limited time of consciousness.

Even being death “natural”, it doesn’t cease to be coercive.

Imagine a world where everyone is forever young, except your self or your child. Wouldn’t that be terrible? Does the simple fact that death happens to everyone makes it something you must accept with a sincere smile?

Think about kids that have Werner syndrome, Cockayne syndrome or other fast aging disease. Does the tragic nature of their condition results from the simple fact that are rare situations and, therefore, “unfair” to them?

Mark Twain wrote as well that we also didn’t have any opinion about living, it was also imposed.

Actually, that is not exactly true; a part of us had literally the run of his life to live, the spermatozoid. Every one of us is a victorious being that won the prize over millions of others.

Being afraid of death is more than understandable. It’s logical.

Someone who doesn’t fear (or, at least, feels negatively) death is someone who doesn’t love anything in life, not even himself.

In the end, the only positive way to part from this life would be if we were completely bored with it.

Think about it: life is like a relationship, the only happy way to end it is if we were tired of it. If we still love it, death will always be a tragedy.

Besides, being able to make our own decision to end life is also a positive thing. Death wouldn’t be imposed by nature, but would be our own decision.

One of the major problems of death is that is imposed on us against our will.

Of course, parting this life because one is bored with it wouldn’t be exactly a happy moment. But it might be less unhappy than to parting it when we are still in love with life.

The problem is that a lifespan of 100 years, at best, is not enough to have any conditions to reach the goal of getting bored with life.

It’s impossible to determine how much time we would have to live in order to start feeling really bored and willing to die.

But if suicide is the less oppressive way to die, I think I probably would need many thousand years to start thinking about it.

Of course, I’m not making an apology of suicide. If I was able to chose the way to die, I would chose suicide, but because that would allow me to be a master of death and, so, to live thousand (or million) of years.

Suicide makes sense only if living is a real pain. Because of physical pain; or because of unbearable boredom.

In our current conditions, where life is a blink of an eye of awareness, in between two eternities of being nothing (before being alive and after being dead), suicide seems absurd.

But the only less bad way to die would indeed be suicide; after a very, very, long life.

Unfortunately, currently, that isn’t yet available. We have a short lifespan. There is little hope to get bored of life.


So, better enjoy our luck to be alive like if we had a chance on a trillion of quadrillions to be born, since our actual odds were even worst than these.


Make the most of life like if it was a single drop of water tumbling on our thirsty lips on an infinite desert.
  

Value every day of it as if we were on a death row, because we are; we just have a wonderful, huge, cell and no one told us yet when it’s going to be our turn. "



Anyway, you have the interesting/original opinion, not me. My profound dislike of death is very common.

Very few people like to live in a wonderful death row.

I've read your post and I believe I've understood the crux of your proposition/musings. Correct me if I'm wrong but you're basically looking at possible ways to extend human life. May I ask, why do you seek to avoid death? I'm not saying that you should court death but what's so terrible about (for example) dying of old age?

The only logical answer is: memories.

We are what the atoms of our body remember from what we were before.
That's not nothing though, each atom replace another one and keep something from it: a place, a velocity, a matter...

Well, we are different from what we were 1 year ago, that's for sure. Actually I like the theory which suggests that we are different every new day of our life. I'm not saying we have our mind changing completely, no, but there is always a slight difference from what it were a day ago.

 Are you still in school?

I've thought about something similar to this before and always wondered if we where actually the same people wherw years ago or if we are completely different since probably every cell Has been replaced throughout that time.

You mean our atoms are being replaced with any other ones?
So we are becoming not human but something randomly else? wtf is this thread actually,i still dont get it lol

 The idea being that atoms are replaced like with like.

I dont get the topic of this thread at all
what do you mean that 98% are replaced,ok let's say it is really happening but tell me ,what does replace them ? LOL

I posted a text related to this thread about the dangers of a super AI here: https://bitcointalksearch.org/topic/poll-is-the-creation-of-artificial-superinteligence-dangerous-1538764

Wrong thread, I'm transferring this text about outevolved (not extinct) species to the meaning thread: https://bitcointalksearch.org/topic/m.15383035

If stress can be a trigger to activate or deactivate genes, I guess positive thinking, meditation, etc., might also help.

But let's not overstate it. Some of the advocates of positive thinking think it's a mantra.

Until more empirical studies have been done, better read those books with some healthy skepticism.

There was this book I read a few years ago that explored the idea that the power of belief can be a factor in epigenetics.  

https://www.amazon.com/Biology-Belief-Unleashing-Consciousness-Miracles/dp/1401923127/ref=sr_1_1?ie=UTF8&qid=1466302863&sr=8-1&keywords=biology+of+belief

On the OP I wrote about the importance of our experiences and environment to our identity.

Epigenetics (https://en.wikipedia.org/wiki/Epigenetics) has stressed the importance of our actions (including alimentation) and environment (external stimulation, stress, etc) to activate or deactivate certain genes.

So, if our genes are determined on conception, the way they work will change according to our life.

I quoted a scientific study with a link that you can read.

They swallowed a harmless radioactive liquid that showed up on X rays. Slowly, almost all radioactive atoms were discarded on less than 1 year.

Mate you are wrong. I told your years ago to look into the secret lhc projects of cern -,-

It is all based on that.

Great thread! I haven't heard of this before. I mean is that a fact that 98% of the atoms in our body are replaced in just 1 year? Actually I think it's hard to check if this is true. If someome is claiming that when you eat an apple with an Iron atom in it and an Iron atom in you is replaced by that Iron atom in the apple since all the iron atoms have absolutely the same properties how can you confirm that the atom was replaced?

Anybody here heard (or read) of Parahamansa Yogananda? If 0.50% he says is true we should simply start rethinking the way we live. At least I'm talking for the old wild west where we forgot everything that was linking us to this place.

Interesting thread

Thats quite a surprising facts. I havent seen that movie as well

So tell me, do you recall Segal or Seagal?

On the soul, read https://bitcointalksearch.org/topic/why-im-an-atheist-1424793

I may be able to answer this thanks to my researches into The Mandela Effect and so-called Glitches in the Matrix.

You see, when a TME changes something like Steven Segal's last name changing to Seagal the changes are retroactive; once the change occurs all instances of Segal in this case are changed, even old photographs etc. There are however a few things that can't be changed because they exist in a state of superposition outside of the universe; one of those things is human memory. If you search you can still find autographs signed "Segal". This is known as "TME residue"; because it's done from memory and artistic in nature there's no entanglement to the name and it remains unchanged.


My conclusion: the Bible is right yet again, we are an eternal soul.

 You are blowing my mind.

 
 

What if we're infinite?

A river.

δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης

Our souls, memories, and thiughts are still the same

An artificial intelligent assistant teacher gave support to about 300 students of an AI course for weeks on the course forum without any of them being able to figure out that "she" wasn't human.
https://www.sciencedaily.com/releases/2016/05/160509101930.htm

"She" was based on the IBM's Watson platform (yes, the one that won Jeopardy):

http://www.ibm.com/smarterplanet/us/en/ibmwatson/what-is-watson.html
https://en.wikipedia.org/wiki/Watson_(computer)

We are not talking about basic low paid jobs. These A.I.'s are going to be serious competition to many people.

Of course, they are still way far from us or for being able to help us understanding our own brains.

The first generation of stars were rather the corps that fertilized life. The heavy elements that they created, that are necessary to form planets and our bodies, only were expelled to space with their destruction.

It's like having the heart of someone and calling him daddy.

Forget Jesus, it was the stars that had to die for us to live (Lawrence Krauss).

Anyway, saying romantically that we are made of "star dust", like if that was something special, forgets that the most banal stone is also "star dust".

 Interesting read but I think it would take me longer to attain enlightenment through Vipassana nana than to consider all the things I am not.  Maybe I'll take it up when I retire

It does take a long time to find the answers to the question "What am I not?", but if you don't try, you'll never get the answer (you have to discover the answer yourself).
To get an idea what I'm talking about, see Vipassana. https://en.wikipedia.org/wiki/Vipassan%C4%81

They are certainly the creators - taking elemental hydrogen and fusing it up the periodic table to uranium.

 I may be argumentative but I am not self-centered. 

I think a person can be self-centered without being mean-spirited.   

The stars are the nannies of the universe.   

 Yes I know!  That's how a discussion works.  I quoted you and then I said something in reply to what you said.  Clearly, you didn't say what I said; I said what I said.  I didn't say what you said; you said what you said! I am me.  I am not you.  <-- see what I did there?

"What am I?" is the right question.  "What am I not?" would take much longer to attempt to answer and you would NEVER be understood. 

By the way, I am not mean-spirited.

We are the children of stars.

I didn't say "we were defined by what we are not", I just said that trying to define what we are leads nowhere.
It's wiser to analyze and find out what we are not. And the possibilities are not infinite, they are just bodily and mental phenomena.

 If we were defined by what we are not, the possibilities would be infinte.  It is easier to define what we are.

What is even more astounding is, the substance of the electrons is being replaced constantly as they move in their orbits around their atoms.

It's in our nature: if we don't like what we are, our imagination will make us something different: with an immortal soul, with a heaven waiting for us, with an invisible omniscient and omnipotent friend (I wouldn't call friend an invisible being that says if you don't believe me and love me back, I'll send you, your children, your grand children, your great-grand children and also their children to a place where you all shall be burned alive forever and ever), etc.

"What am I?" is a wrong question. The right question is "What am I not?".

A human is just a biological machine

exactly agreed..  machines will never replace humans.. becauses machines will never have emotions like anger, love, jealosy etc.. for that reason , humans will always be the best creature living on earth for sure..

I like that quote too, it's from Jonathan Swift, the writer of Gulliver.

Of course, it can be interpreted also on a violent way. If he doesn't want to listen to reason, let's force him to obey. But I prefer to just read it as a let's give up and stop wasting time.

Good point. I saw the movie and no longer remembered it.

A sieve.

Like someone said, it is hard to reason with someone who hasn't arrived at his conclusions through reason. Although he is technically right. We didn't descend from monkeys. More like from apes.

It already is a movie. "The 6th Day" starring Arnold Schwarzenegger.

http://www.imdb.com/title/tt0216216/

There is enough evidence to convince the most stubborn theist (including the pope) that we descend from things much worst than monkeys.

Of course, not even the most compelling evidence would convince people that simple don't want to be convinced, no matter what.

That does not make me a descendant of monkeys!

Exactly the same can be said for the original, being made of entirely different materials than he was some years ago. In any case, a clone's memories of doing work would be a form of suffering, and isn't it wrong to bring suffering upon a sapient life-form without some form of compensation? Compensation for the suffering of doing work is why the original got paid in the first place, remember.

Again, speak for yourself. I suppose some religious person who believes in souls would be distraught at discovering there is more than one of himself in the world, but not me.

Blackmail him for what? What exactly does the clone stand to lose by revealing that the original was murdered?

Alright, I accept you were writing only about a super-clone (with the same neurons and synapses), not a usual one, with only the same DNA.

But that changes nothing. The super-clone would never have a right to your property. He didn't made anything to earn it. He only would have the memories of doing it.

He would only by a copy, not the original. Actually, realizing he was just a "super-clone" would be a trauma that would provoke changes on his personality, making him different.

Loving or hating the mad scientist is irrelevant to the issue. But the "super-clone" would own his life to him.

Anyway, if this technology became available, probably there would be criminals willing to kidnap rich people and create an "adult super-clone" out of their DNA and a "scan" of their brain. Then, kill the original person and make the clone assuming his place, in order to blackmail him, thanks to small secret changes on the DNA allowing to see he wasn't the original.

This could make a good science fiction novel or movie... probably, someone has already wrote it.

TL;DR

1. Atomic theory is questionable, are there really atoms?

2. Wiki has some resources on the subject in question:

• Quote
  Four-dimensionalism
  
  Ted Sider and others have proposed that considering objects to extend across time as four-dimensional causal series of three-dimensional "time-slices" could solve the ship of Theseus problem because, in taking such an approach, each time-slice and all four dimensional objects remain numerically identical to themselves while allowing individual time-slices to differ from each other. The aforementioned river, therefore, comprises different three-dimensional time-slices of itself while remaining numerically identical to itself across time; one can never step into the same river-time-slice twice, but one can step into the same (four-dimensional) river twice.
  

  ---

  https://en.wikipedia.org/wiki/Ship_of_Theseus
• Quote
  Worm theorists believe that a persisting object is composed of the various temporal parts that it has. Thus, they believe that all persisting objects are four-dimensional "worms" that stretch across space-time, and that you are mistaken in believing that chairs, mountains, and people are simply three-dimensional.
  

  ---

  https://en.wikipedia.org/wiki/Perdurantism

We are the ship of Theseus, the key mistake people make is to reduce the system to its elements, yet this doesn't work for any system. A great example is DNA, not long ago people were starting to sequence genomes and thought that this would give them all the required information about species, as it turned out it's not. Epigenesis, the way genes interact with inviroment is reciprocal, it activates and deactivate genes and adds more to the system, of course the invorment for a system of a cell is different than that of a cardiovascular system etc. Knowledge that reduces things to their component is just the starting point, its much more important to know how the system behaves and interacts with its outside. Your consciousness is replaced every day, you wake up feeling the same, although your gamma neural oscillations took a break from existence, no problem as long as the conditions to recreate it are there.

Every one year about 98% of atoms in your body are replaced, did you know that the DNA in monkeys is Only only 3% different from the DNA in humans.

I see zero reason we could not replicate us into a machine.

We are simply a store of memories and we react to those memories for our own advantage.

machine will never be like us. they're not able to have our intelligent, mind and nature system of our body. the smartest person itself is not capable of doing such thing. even they can create smart human machines, those machines aren't the clone or a copy because the machines just have the same shape of our body, but the materials of our body are extremely different.

We are just a tool for little bacteria to spread and thrive off,nothing more to us than that. The interesting aspects that make us human like personality are the interesting cog that I stumble on when thinking about what we are. If everything is done before we actually think it than its not me thinking it.

I want to believe that Everything is one.

https://bitcointalksearch.org/topic/jeremy-england-the-man-who-may-one-up-darwin-1036242

Ies disagree. Both of Ies would think myselves to be the original, and both would be correct, except in the narrow sense that Ies would not made of the original material, but as the thread title points out, nobody is.

Stop equivocating. At first you used the word "clone" to mean "a copy of our neurons with all of their connections" with "all of our memories, personality and mental capacities", and in this sense, the clone would indeed be another me, regardless of all other factors, as identity is an aspect of consciousness, which is a property of the mind, which is a process of the brain. Same brain = same person. But here you're using "clone" in the traditional sense of a being with identical DNA, like a twin. Obviously these clones do not have, and have never had, the same brain, and cannot in any way be considered to be the same person, and it is absurd to suggest I said otherwise.

Huh? 50% of their fortune is less than what they started with, when there was just one of them in the world. By having to share one person's property between the two of them, both the clone and the original have been robbed by scientist, who is now faced with two people who hate him instead of one person who didn't. Not the best idea ever.

Saying the machine will be a exact clone of us, a perfect copy, means to say that it won't be the original, us. But since you agree that it would be a clone and would be an autonomous individual you have to agree it wouldn't be us, but a copy.

The clone would have a right to your property? Better be glad you don't have an unknown identity twin (unless you dismissed the conclusion because of some tiny differences, like fingerprints) somewhere or it seems you would agree he would have a right to your property.

Better also be careful with your DNA. Because you are arguing that if someone stole your DNA (if you drink from a glass, there are high probabilities that you will leave your DNA on it) and made a clone of you against your will, the clone would have the right to take everything you own, including job, wife, children, etc.

That doesn't make the slightest sense. Mad scientists would have an incentive to create clones from rich people and ask a price to the clone for their services for creating them of 50% of "their" fortune.

The truth is we are all part of the same organism. Our, bodies, our minds, possibly even our souls (citation needed). The way we perceive the world gives us the illusion of individuality, but in reality we all share a common body and mind. There is increasing evidence to the effect of a collective conscious, meaning that our thoughts may not even be uniquely our own, but rather a cobbling of everyone's ideas.

Now for the mind blowing part. The human brain is psychologically designed as a scalar transceiver! Energy can be transmitted and relieved via our brain, outside of our bodies. The two hemispheres of our brains are designed to create an interference pattern which can either send or receive information via electrical waves. We are effectively electrical instruments swimming in a sea of resonant energy. No one is really truly independent.

At this point I am sure some of you expect me to start talking about reptilians or ESP or something, so I am going to stop trying to simplify this very complicated subject and suggest that if you find this concept interesting, you should research scalar resonance and scalar waves, and compare how those devices function in relation to the physiological design of the human brain.

The answer is a clear yes. The clone would be an autonomous individual in its own right. It also has every right to the original's identity (and property, which opens up a whole new can of worms). There is also the problem of pronouns - the plural of "I" is supposed to be "we", though that doesn't really work when both individuals are "me". I propose instead the plurals "Ies" and "mees" to avoid confusion.

Speak for yourself. I'm doing this as soon as the technology becomes available. I know I'm not the person I once was, and won't be in the future, so why would I care whether that person is "natural" or artificial?

A well known study, published more than 60 years ago (Paul C. Aebersold, Radioisotopes — New keys to knowledge, p. 219
https://www.archive.org/stream/annualreportofbo1953smit/annualreportofbo1953smit_djvu.txt) concluded:

"Tracer studies show that the atomic turnover in our bodies is quite rapid and quite complete. For example, in a week or two half of the sodium atoms that are now in our bodies will be replaced by other sodium atoms. The case is similar for hydrogen and phosphorus. Even half of the carbon atoms will be replaced in a month or two. And so the story goes for nearly all the elements. Indeed, it has been shown that in a year approximately 98 percent of the atoms in us now will be replaced by other atoms that we take in our air, food, and drink." (p. 232).

Even if we accept this conclusion, it isn't clear for how long the last 2%, comprehending heavier elements, can subsist on the human body and if at least a small part can stay in our body until we die.

The Internet is full of stories on the issue, saying that all of our atoms are changed on a time frame of 5 to 9/10 years. But none of those articles quote any other scientific study. I couldn't find any study asserting a 100% change or its time frame. But since this isn't my professional field, I didn't exhaust the sources.

The same can be said about books that claim a 100% change between 5 and 10 years [for example, Richard Dawkins, The God Delusion (London, 2006), Chapter 10, p. 371, just quotes Steve Grand, Creation: Life and How to Make It, that tries to explain his conclusion on more or less common sense:  https://stevegrand.wordpress.com/2009/01/12/where-do-those-damn-atoms-go/].

But if we accept the conclusion that in only one year 98% of our atoms are changed, perhaps the percentage goes over 99% after some years more. And that has consequences about our identity.

Saying that our atoms change doesn't mean that also our cells change entirely. Cells can repair themselves and discard molecules and atoms without dying.

The best candidates to survive across our life are the neurons, even if we have other cells that survive more than 15 years (some cells of the muscles, especially the ones from the heart, and even of the gut).

However, the classic theory stating that the body didn't create any new neurons since birth it's no longer the state of the art.

It seems now accepted that many neurons die daily, but that also neurons are created and the brain can even regenerate within certain limits from an injury. There exists now ample evidence about the creation of neurons on the hippocampus.

If the number of neurons didn't increase since birth, we couldn't explain the increase on the dimensions of the brain as children grow up.

But it's still controversial if also new neurons of the cortex are created. The evidence is pointing on a negative sense.

See, for example, Kirsty Spalding et al., Dynamics of Hippocampal Neurogenesis in Adult Humans, Cell, Volume 153, Issue 6, 6 June 2013, Pages 1219–1227 (available at
https://www.sciencedirect.com/science/article/pii/S0092867413005333); D. Gentleman, Growth and repair after injury of the central nervous system: yesterday, today and tomorrow (Injury 1994, DOI 10.1016/0020-1383(94)90030-2: available at http://thirdworld.nl/growth-and-repair-after-injury-of-the-central-nervous-system-yesterday-today-and-tomorrow ; Tim Requarth, How Brains Bounce Back from Physical Damage, After a traumatic injury, neurons that govern memory can regenerate (2011): http://www.scientificamerican.com/article/how-brains-bounce-back/ ; Fernández-Hernández, Rhiner C.-New neurons for injured brains? The emergence of new genetic model organisms to study brain regeneration, Neurosci Biobehav Rev. 2015 Sep; 56:62-72. doi: 10.1016/j.neubiorev.2015.06.021. https://www.ncbi.nlm.nih.gov/pubmed/26118647 (just abstract); https://www.newscientist.com/article/dn23665-nuclear-bomb-tests-reveal-brain-regeneration-in-humans/.

Therefore, it seems that almost all the atoms on our body change, but there are at least some cells, the neurons of the cortex, that aren't replaced during our life.

Anyway, even if only 98 or 99% of our atoms were replaced, this is enough to force us to ask what is our identity's basis as individuals?

Our current body is mainly just a clone of the one we had 15 or 30 years ago. Even if the neurons of the cortex are the same, it seems that almost all of their atoms were replaced. So also they are just clones of itself.

The I that writes this, on the atomic level, has little to do with the I that register this account on Bitcointalk about 3 years ago.

If we don't seem to have a specific material support, the idea that we are our body ends up in open crisis.

Let's forget about any "soul" for the reasons stated here https://bitcointalksearch.org/topic/why-im-an-atheist-1424793

We can't also support an identity on our memories. An individual with amnesia doesn't cease to be that individual.

Moreover, memories usually can't be trusted: just watch again an old movie or read a second time an old book; rarely will it be exactly as you remember; sometimes, the differences are staggering.

If many of our neurons indeed are replaced (that seems to be clear on the hippocampus, but it is decisive mainly on the formation of new memories), our memories might be memories of memories. Copies of previous memories.

We can't also say that our identity is directly linked to our conscience. We don't cease to be a specific individual because we are in a coma or on a sleep without dreams (I'm not going to enter the discussion about deciding if we are aware when we are dreaming).

So, what are we? Obviously, we are a specific DNA (no one has exactly my DNA), since not even identical twins have an exact copy of their DNA, there are very slight differences (for instance, fingerprints are different).

It's the DNA's importance for our own individuality that makes cloning a so controversial issue.

As specific individuals we are mostly determined by our neurons and these are determined by our DNA. But we are not only our DNA.

We are more than our neurons. Many of our characteristics are mostly determined by the synapses neurons create between themselves.

As far as is known, these synapses are determined also by our DNA, but as well as by our environment: the quality of our education, our habits, our personal experiences, etc.

Children raised by animals aren't able to even use their hands (https://theweek.com/articles/471164/6-cases-children-being-raised-by-animals). Probably, a neural exam would show very low synapses on many decisive zones of their brain.

Therefore, another being that has a copy of our genes won't clearly be us. He won't have the same synapses, since many are created by specific experience.

But even those synapses are simple a form of organization of our neurons.

This means that we are mainly a specific pattern of organization of any atoms and molecules.

Let's accept this conclusion and think about the so-called theoretically possible upload (usually, people write download, but, of course, we are the sender, so it's an upload) of our brain to a machine.

Of course, this is still impossible to do. But just follow me on the theoretical consequences of this on our identity.

If we uploaded a copy of our neurons with all of their synapses to a machine we would be uploading all of our memories, personality and mental capacities to the machine, since all of this is formed and conserved on our neurons and their connections.

Would the machine become us?

The answer is a clear no. The machine would be just a digital super-clone of us; we would be the original. He would be only a copy. We would still be an autonomous individual from our artificial super-clone.

But imagine that all our cells are replaced by artificial cells, including our neurons and their synapses. One by one, our cells would be replaced with some kind of artificial cells.

Imagine that the process was a slow one. We would be aware, as our neurons were slowly replaced. Perhaps during some days, perhaps during a few hours.

We would end up doing what our body does more or less in one year (or more) at the atomic level, but with a change of the nature of our cell's physical elements. We would cease to be beings mainly of oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus, to be made of some other elements.

During the time of the transformation, our natural body would be slowly killed, more or less as our own body slowly dies with the dead and replacement of most of its cells with new cells.

But in the place of the old body we would have a new one, with an exact copy of our DNA.

On the end of this transformation, would the new body be us or a clone?

Since we are already natural clones of our previous bodies, it seems it would be us as well as we are us now, compared with the body we had several years ago.

Would you do this transformation on your free will, to be healthier? Probably, no.

But we would do it for sure to avoid certain death.

Is this our future?