what are we “made of”?

Dear friends of savagephysics… today I will discuss a very interesting aspect about reality and some western myths… first, the part about reality: greek philosophers started speculating about it but the idea was continued until modernity and accepted by the scientific community as a truth and by the “materialist dogmatics” of the 18th ,19th and 20th century. Today almost any scientific blog or popularization site will tell you the same thing: we are made out of atoms and the poetic twist : “we are made out of atoms, atoms try to know themselves through us”… now, I really don’t care about poetic license so please feel free to say that stars and galaxies and whatever you feel an attraction for are trying to know themselves through us… you may feel even somehow important through this but also, please let me tell you where this way of thinking fails. 

When we started discussing about probabilities in nature and about statistical mechanics and quantum mechanics we started observing all sort of strange things. These were called “paradoxes” but were subsequently explained pretty well by scientists. One of these “paradoxes” has its origin in an misfortunate use of some words… well, most of the quantum “paradoxes” have their origin in this… let me be more specific: I am talking about “Schrodinger’s cat”… it was a sort of wanna be gedanken-experiment invented by Schrodinger that became so popular mainly because it has the word “cat” in it… (so, if you want to become popular just use cats in your experiments). The experiment is however fundamental for the problems I stated in the first paragraph so, let me explain what it does: take a simple whole cat and put it in a box. Take some poison that once released could kill the cat and make so that it becomes active when a Geiger device detects the first radioactive decay of an atom. Prepare the system such that it is in a superposed state (quantum state) of decayed and not decayed and start measuring. Now, the situation becomes interesting because there are several wrong ways we can use our language to describe this experiment. Let’s start by thinking where do we consider a statistics? Well, that is a good question: essentially nowhere… the first radioactive decay will trigger the death of the cat and we described the cat as a single object so we are generally not even asking a good quantum mechanics question in the first place, but let us continue assuming that we ask about probabilities to be calculated on some samples of cats and atoms decaying. Then the answer is clear and plain: half of the cats will be dead in the end after an interval T calculated from the properties of the atoms. 

The paradox in this problem appears when you ask how will be the cat before the measurement of the state of the atom? Will it be a “undead cat”? Will we have Zombie cats moving around unobserved boxes? Of course NOT! If you look more carefully you will see the question above is not well posed. While you can add a wavefunction to the statistical description of an atom and get a probability you cannot use the same framework for the description of the cat. The two objects are incompatible. There is no well defined “cat” in the basis of radioactive atoms in a superposed state. The cat is a macroscopic object… entanglement defines how a “whole” and “its parts” are different from each other so you cannot in principle use the same language on one side and on the other of your experiment and expect to get meaningful answers. While you certainly could define a cat using only atomic wavefunctions you will have a HUGELY hard time to find out what the wavefunction is and what kind of entanglements and correlations are there and the end result will most likely have nothing from what we interpret as a “cat” … 

So, we cannot use atomic wavefunctions and cat wavefunctions simultaneously because we don’t give a complete description in either of the situations. 

Back to the question: what are we made of? This is a rather typical western culture question with a strong bias on things being made out of other things and so on. It is almost a biblical way of thinking if one has to trace back the origins of the concept. We are made out of large molecules, large molecules can be split in smaller ions and molecules, they can be split in electrons, protons and neutrons and they can be split in quarks, gluons, photons, leptons, weak bosons, higgs bosons, and so on… this way of thinking however interesting may look like is not a valid description of our reality at our length scale. There is a huge amount of information that we never considered when doing all the splitting so the fact that in the end we end up with “elementary” particles is primarily irrelevant for the way nature behaves at the scale we observe it usually. Do I talk about renormalization group? In a very distant way, maybe… there can be made a connection to the marginally relevant operators there but then again, that is not the full story. The full story is to acknowledge that the information about our macroscopic reality is not encoded in the fundamental building blocks and fundamental laws at a very small scale. 

Now, let’s go back to the ages of string theory… this idea came into being because we needed something fundamental enough to rely upon and this was, ab definitio the string. This idea did not work at all… some of the simplest dualities (like T duality) already showed pretty clearly that there is no way of finding out some relevant concepts about our reality from the very basic “fundamental building blocks” of it. It is a very western myth the idea that “fundamentality is necessarily something small that constitutes the building blocks of everything”. This is not so. I can say this quite surely by now and most of the better string theorists admit that finally too… The “fundamental string” is not fundamental at all… it is just a mathematical concept, a sort of “wavefunction” which may ease our understanding of some aspects but it certainly makes the understanding of other concepts harder. 

This is pretty hard to understand but, surprisingly so, quantum “fundamentalists” understand that relatively better nowadays… If I tell you that you are made of carbon, oxygen, nitrogen and some hydrogen atoms you will notice that what I told you is meaningless. It can be “poetic license” but it still remains completely pointless… While you understand that, many scientists still believe that the whole information about “the universe and everything in it and all that stuff” is somehow encoded only in the way in which their fundamental building blocks interact at the level of high energies… This is of course nonsense… 

Indeed, the whole is probably not more that the sum of its parts but it is something different that needs another framework in order to be correctly described… 


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