SBF:
bohm according to the video above about how physical cloning is not possible, it says that an extremely close approximation is theoretically possible but that quantum mechanics prevents an exact physical clone without destroying the original in the process of retrieving the information. A resurrection does not involve replicating or destroying one original, but extrapolating from numerous points in the past to recreate a being which resembles multiple point but may not be exact to any given one.
My point is that the problems with chaos theory are much more severe. I am with you that we don't need an exact clone, but an approximate clone too is impossible. I suggest we keep quantum mechanics completely out of it as I think it is just confusing the real problem:
Let's suppose "you" consist of just 100 atoms in a completely empty room with perfect walls. Let's assume for simplicity the atoms are atoms of gas and when you are "alive" that corresponds to the atoms being in a ball in the middle of the room.
That you "die" means the atoms evolve according to the rules of classical mechanics -- they fly apart and begin to bounce off the walls of the room. This is not a poor model if you are cremated.
An alien civilization could then look at the configuration of atoms at a later time (where they would be distributed evenly in the room), measure the location/velocity of all atoms, and use the rules of classical mechanics to re-construct you (and an approximate reconstruction will do). That seems pretty simple and nothing in physics prevent this (let's assume we are dealing with classifical physics).
Here is the problem: Let's suppose we look at you just after you "die" and focus on one of the atoms. Suppose we know the location, velocity of that atom to a tremendous precision, except we are just ever so slightly uncertain about the location of the atom (assume we know it to the width of an atomic nuclei). Suppose in one case we know the exact location of all atoms, and in another case we know the exact location of all atoms except this one where we get the location wrong by the width of a nuclei. atom, and in another case we know
The problem is that this atom will eventually hit another atom, and that small uncertainty will affect the angle the two atoms then scatter (both atoms). As time progress that means the location both the atoms will become more and more different in the two cases. Then two two atoms hit two other atoms and now there are four atoms that are affected by that initial uncertainty. Then these four atoms hit four others and then there are eight and up we go exponentially until all atoms are affected. My point is that this idea holds for all atoms: Affect one atom and you affect them all.
But it gets worse: Since the uncertainty affecting each atom involved in the collisions keeps growing too, at some point the uncertainty affecting any of the atoms reaches the width of an atom at which point it might miss a collision --- that this collision happens or not will eventually affect all atoms, in other words you get a completely, different configuration of atoms just because you changed the location of one atom by the width of an atomic nuclei. This is known as the butterfly effect. Are you with me so far?
This thought-experiment was about what happens as you decompose and time moves forward, but the same holds if we assume we measure the location at a future time and tries to predict the past: Time dynamics are reversible.
So if you measure the location of a single atom wrong (by the tiniest amount), that will mean your conclusion of the past will become completely random: you will conclude the atoms that make up "you" were not actually formed as a spherical ball in the past, but as a random configuration in the room -- i.e. a gas.
There is another way to phrase this: The precision at which you need to know the present to predict the past grows exponentially.
We can continue this thought process a bit. Atoms are not static but absorbs and emits photons. When they emit a photon, that photon will carry momentum and thereby to know the exact momentum of the atom originally, you have to measure the momentum of the photon as well (and remember we do need to measure the momentum exactly because of the above problems).
This is not a problem in the room where we can put photo detectors on the wall, but in real life some of those photons will shoot into space and fly away at the speed of life. Since the alien civilization can't measure those photons that creates an inherit uncertainty in their ability to reconstruct the past. In other words the project becomes impossible.