Today we going to talk about Copenhagen Interpretation of quantum mechanics!
I was surprised that smart people still think that Quantum Mechanics requires some sort of “observers” and assign mystical significance to these “observers”. As if Universe “needs” observers for QM to work. The universe is far more elegant, symmetric and scale-free and doesn’t require any “observers”!
Let’s start at the very beginning.
The universe that contains only gravity is “boring” – everything simply rotates around the center of mass, and nothing happens. The universe with only ThermoDynamics is “boring” – everything is just flying away from each other, and after universe cools down next to 0 everything is dead.
Now, our universe is interesting because it has both gravity and thermodynamics! Gravity wants to pull things together; thermodynamics is pushing them out – especially if there is an energy source, which is quantum mechanics. Everything that ever happened, happened only because gravity made it possible by keeping all the stuff together, while thermodynamics forced it to burn and change.
Thermodynamics has a strong connection to information – thermodynamic “burn” always tries to destroy information. TD process always increases the entropy of the system from more ordered to less ordered.
Notice that gravity is the opposite – it is a pretty ordered thing! The gravity-only universe will be a graveyard of course, but pretty orderly one. Everything on its orbit, and is at its designed orderly place – forever.
You get energy out of that thermodynamic burn, but make no mistake – the price of that energy is permanent destruction of order and information. When you bask in warm sunlight, you are literally basking in the heat of information being burned away. We live in a permanent totalitarian thermodynamic
Now we know that there are many processes that we call “thermodynamically irreversible” – a process that destroys information so well (or increases entropy) that you can not revert it back.
For example, bouncing a soccer ball on the head is trivially reversible interaction – simply direct the ball back with opposite speed/momentum, and ball/head system will revert where it was.
In contrast, a bullet to the head is well known to be entirely thermodynamically irreversible. Consider: if by a very very lucky chance bullet will pass through the head missing any vital organs, leaves no splinters and enter/exit cleanly – the whole passage is very orderly. And that usually the kind of wound that gives the patient the best chance of recovery. But if bullet splinters (chaos!), and in turn splinter bone and brain into goo (more chaos!) – it’s game over. Information is lost forever; entropy is increased permanently. Thermodynamically irreversible process.
What we need to remember about TD processes is that they are like a one-way gate: it’s easy to go in one direction, but it is incredibly unlikely to go back the opposite way. There is a tiny chance that all particles in the after-bullet head will jump to the exactly right orderly positions where they should be, and bring a dead person back to life, but in general, that doesn’t happen. Anytime we do “observation” in QM we always trying to trap something into that one-way gate so it never can go back to pure QM world – by killing QM information same way as bullet kills a person by “averaging out” particles in his brain.
Now, with quantum mechanics, the fundamental concept is “entanglement“. When any two quantum particles interact, they get entangled. That means they are not two particles anymore – they are somewhat of one thing while they are entangled, and yet they remain separate quantum particles. And it’s not limited to just two particles – any number of particles can be entangled!
While particles are entangled, all sort of crazy QM effects you read about in the books are happening (particle-wave duality, passing through both slits at once, Bell inequality, etc). Particle entanglement is like finding soul-mate or a few soulmates in your life – you are so close together, that you are separate but you are whole as well, and bigger than the sum of its parts. People who had been in deep and meaningful open relationships understand “entanglement” between multiple parties very well.
Bell inequality experiments repeatedly proved that “fate” of one entangled photon immediately affects the “fate” of its entangled cousin – even if he is half a galaxy away, instantly! And in the most mind-bending way, it happens in such a manner that it does not break lightspeed limit on the transmission of information. Just by watching the sky your eyes affect quantum properties of photos many galaxies away – you consume their entangled cousins by watching, and they feel it!
“They are the one – the Dark Lord, and the Ring”. Yes, they are entangled! If Frodo manages to TM-irreversibly collapse wave function of the Ring, the same thing happens to the Dark Lord.
There are ways to entangle particles that ‘kills’ their previous entanglement. That’s pretty much how any measuring device works. Think of this: the entangled state has incredibly rich, extremely multi-dimensional quantum information. The measurement we humans need from our instrument is something very flat, like ‘this battery is now 12.1 volts’. Human-friendly measurement destroys information, vasts amounts of it.
So every time human-friendly device measures something, it only works because it is built on the thermodynamically irreversible process. Every time humans measures or sees something in the world, it the act of killing a massive amount of quantum information! Maybe that’s why true Buddist is trying to separate itself from the world – it doesn’t want to kill it by observing it with monkey eyes.
That’s how we got that myth of “observers” that are somehow “required” by quantum mechanics. Nothing is further from the truth.
You need observers, i.e., measuring devices, i.e., devices that collapse all entanglement and force the particle to entangle only with measuring system to destroy the QM information, and print some averaged out classical value – like speed, position, etc. that monkey eyes and brains can observe – that is the only reason! The root of observers is classical requirements of monkey eyes, that need classical instruments, that can only work by massive averaging out and giving something flat as a result.
But the universe as a whole doesn’t need any observers! Some particles born in the Big Bang itself are floating through the universe, entangled with everything they come near, and float on their journey toward The End. As an interesting sidenote that will certainly give more food to simulation hypothesis fans: photons born with Big Bang (i.e. not starlight photons) and who manage to not get entangled with anything till The End (i.e. every non-observed cosmic background radiation photon) – such photon whole lifetime would be exactly… zero. Since photons move with speed of light along the space axis their speed along the time axis is zero – locally for photon itself Big Banf and The End is an exact same moment of time. If it did not get entangled with anything in the observable universe, the whole lifepath of such photon is inconceivable 0-length by local clock instant during which … nothing at all happened and nothing at all needs to be recorded since such photon did not touch anything. It can be totally erased from any consideration since nothing at all changed. Life advise to particles of our simulation: do get entangled with stuff or you will get garbage collected as 0-instant null value!
Only when a human comes along and wants to measure something about our traveling photons that eternity of entanglement is now forced to wave-function collapse to produce some averaged out reading that aforementioned human can print in a journal and finally get that long sought after tenure. He cannot print “entangled” quantum data because it is entangled with the universe, not with him! There is no tenure in that; he needs to collapse it to print something specific.
Measuring classical information is like dynamite fishing in the quantum sea. We are creatures that never ever can go and swim inside that quantum sea – we are bound to always however above. For us, humans, quantum fish is always floating here and there in that entangled ocean, position, and velocity always uncertain. So what we do? We just drop an H-Bomb that kills all the fish in the big area and makes it float to the top. Then we measure and say “Hey, this particular spot in the universe had 5,123,456 live fish, now they are deterministically floating belly up on the surface not entangled with anything else, so we can count it up“. And then you repeat the same thing next microsecond, and the next, and the next. Any classical observation is an act of averaging out – killing all that quantum fish and finding a way to count them as a whole.
The famous Schrodinger Cat paradox was a paradox only in the early days of QM when all implications of QM connections to thermodynamics and information were not fully understood. There is no paradox. The cat is specifically alive or dead in the box no matter did you ever open the box or never open the box. The “observer” is a thermodynamically irreversible process of using a measuring device attached to the poison capsule and an equally thermodynamically irreversible process of death. Cat never was entangled and never becomes entangled just because somebody attached measuring device to the quantum source. The wave-function collapse happens from inserting the TD-irreversible step into the system – our human measuring device. Quantum system was entangled until our measuring device captures the result – that’s where the quantum state ends. Rest is just window dressing that something else happens after TD-irreversible event of measure.
In summary, Universe and Quantum Mechanics work perfectly well without any observers ever entering the universe. Particles just move around, sometimes entangling with some, sometimes disentangling, some processes being TD-reversible, some not. The universe doesn’t care, and for universe photon entangled with its cousin born 13B years ago in big bang (true for each CBR photon out there!) is as perfect, as a photon which just got entangled with an electron in eager scientist camera silicon array, and therefore lost entanglement with everything else. But scientist got the reading that pixel color is “red” (while destroying – literally – a universe worth of information) and got his tenure.
Humans bring forward the concept of observers, of measuring devices because we never could, and, until our perception organs radically change, never will be able to perceive the whole depth of multi-dimensional full quantum mechanical information of a given system. Even “perceiving” is the wrong term, since it implies static consumption, which in turn implies thermodynamically-irreversible entanglement with us rather than staying entangled with the rest of the universe. Observers (of either kind – own eyes or devices) are fundamentally just information-killers that send us dead bodies only valuable to this specific monkey tribe: averaged out values of the quantum ocean that monkey perception can work with practically.
Perhaps true quantum-sentient entity in humanity future will be like a Buddist monk who is in tune with the whole universe (entangled) but not bound by that perception (no TD-irreversible collapse just to consume). Then we finally will have no biological monkey-race need to be information-killing observers of Copenhagen interpretation.
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