What is Decoherence?

A lot of times decoherence is thrown around and there's a lack of understanding as to what decoherence is and what decoherence says.

First, decoherence doesn't explain the measurement problem. In fact, decoherence tries to avoid measurement by saying there's an apparent collapse.

In quantum mechanics, quantum decoherence is the loss of coherence or ordering of the phase angles between the components of a system in a quantum superposition. One consequence of this dephasing is classical or probabilistically additive behavior. Decoherence occurs when a system interacts with its environment in a thermodynamically irreversible way. This prevents different elements in the quantum superposition of the total system's wavefunction from interfering with each other. Decoherence was first introduced 1970 by the German physicist H. Dieter Zeh and has been a subject of active research since the 1980s.[1]

Decoherence does not generate actual wave function collapse. It only provides an explanation for the observation of wave function collapse, as the quantum nature of the system "leaks" into the environment. That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. Specifically, decoherence does not attempt to explain the measurement problem. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the "realization" of precisely one state in the "ensemble".

en.wikipedia.org...

The reason you have all of these different interpretations of QM is because things like decoherence don't answer these questions but impose more questions.

For instance, decoherence says an objective state doesn't exist. It's just an apparent state of a mixture of probable states. You have a pure state of a quantum system, say 60% chance of spin up and 40% chance of spin down. When the system interacts with it's environment, decoherence goes from a pure state to a mixed state but you still have the same probabilities. The phase coherence just leaks into the environment and this means the probable states can't interfere with each other. Decoherence doesn't explain why an observer sees just one state and not the other. Herein lies the measurement problem.

When do these probable states take a state that's observed and measured? What cause the wave function to "collapse" to a Dirac Delta function when one of these probable states is observed?

Decoherence doesn't explain this.

This is why things like Schrodinger's cat is still hotly debated. The way Schrodinger set up the question still leads you to a live/dead cat. Here's what he originally said:

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.

It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naively accepting as valid a "blurred model" for representing reality. In itself, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.

—Erwin Schrödinger, Die gegenwärtige Situation in der Quantenmechanik (The present situation in quantum mechanics), Naturwissenschaften
(translated by John D. Trimmer in Proceedings of the American Philosophical Society)

en.wikipedia.org...

The key point here is this:

1. He's talking about an isolated system within an isolated system. The radioactive substance is isolated from the cat and the cat is isolated from the outside environment.

Decoherence doesn't answer the question. When does the cat or the radioactive decay decide to be in one state or the other? How can it decide without an outside observer interacting with the information inside the box?

So the cat has to be live cat/dead cat until a measurement occurs which is decay and the cat dies or no decay and an observer opens the box and sees a live cat.

This opens up questions about our universe and do we ever actually exist in a material universe. When does the actual universe become the universe or is it an approximation of a pure state? So the universe never exists just some approximation as to what we perceive to be a universe.

There's something called decoherence time and this is the time it takes for a system to lose it's phase coherence. With smaller systems like particles, it can take a long time. With larger systems like a cat it can be instantaneous. This occurs when the system interacts with it's environment. If the radioactive substance was isolated from the cat and the cat was isolated from the outside environment then the cat is in a superposition of live cat/dead cat until information about the system(cat) reaches the outside of the environment or a measurement occurs in the box and the cat is dead.

Again, decoherence doesn't tell you in which state the cat will be found in when it interacts with the environment. In fact until it interacts with the environment it doesn't have a definite state. So unless there's something outside of the "universe" that measures the universe then reality doesn't exist. What we call a universe is just an approximation of measurements that conscious observers call a universe. So what we call reality doesn't exist until measured and even then it's an approximation of a pure state that conscious observers call "reality."

Here's a quick video about Schrodinger's cat that shows you why these questions are still out there and decoherence doesn't answer them. How can the wave function be physical? How can anything physical be in a pure state? Again, the key thing to remember is, THERE IS NO CAT.

Just another decimal point beyond? the last and the last decimal point.
If you measure a quantum object, you might find it in a particular state. But it makes no sense to ask if it was in that state before you looked. It's but another tree that fell while nobody heard it, therefore never made a sound, which it obviously did.

If a fat girl falls in the forest and no one is there to see it do the trees laugh? Just a t-shirt I found online.

Schrodinger's cat has too many inconsistencies to ever be suggested a universal application. The theory needs revision. Decoherence/coherence exists, it's just not as abundant as speculated. Observation of the paradox of states, typically employs an electron microscope. That alone corrupts the data's integrity. Sure, it proves the processes of electron microscopes observing particles have a measureable effects on the quantum scale, but to me, that just lends credence to further implications related to electrobiology. Relations with the power of Intent, Observation, and the body's capability of discharge and direction of potential particles, and their resulting entanglement with subject, on a sub-atomic level.

"How can the wave function be physical? How can anything physical be in a pure state?"


What potential exist that the human condition has an effect upon the wave function?

How is Human and Animal DNA, as an example? In relation to its order. Interact in a system that conservative scientist claim is random, upon the grand scale of everything?

In reality Chaos theory is specific in relation to the conclusion, that perceived random systems, at the grand scale, are actually Non- Random.


Decoherence and Death seem to have something in common and what separates them perpetually seems to be Time.

Any thoughts?

a reply to: neoholographic

Decoherence seems like a good way for life to form and its to say that otherwise it would be really difficult to find food.

originally posted by: neoholographic
Decoherence doesn't answer the question. When does the cat or the radioactive decay decide to be in one state or the other? How can it decide without an outside observer interacting with the information inside the box?

No outside observer is needed, just put a camera inside the box and the camera will record what happened before the box was opened.

Critique of "Quantum Enigma: Physics encounters Consciousness"

I share Steve Hawking’s impulse “to reach for my gun” (ref. [2], p. 120) whenever Schrodinger’s cat story is told. This cat story is notorious. It requires one to accept that a cat, which can be in innumerable different states, can be represented by a two-state wavefunction, a bit of nonsense which Schrodinger himself originated. However, a movie camera installed in the box containing the cat would record a cat that is alive until the unpredictable moment that the radioactive nucleus decays opening the bottle containing cyanide thus killing the cat.

a reply to: Arbitrageur

What purpose does a "Camera" serve without someone capable of understanding the information?

a reply to: Kashai
What purpose does killing the cat have? It's a thought experiment that doesn't have any purpose except to make you think.

a reply to: Arbitrageur

I think Decoherence=Death.

One day Carbon atoms will emit radiation.....

The apparent relevant factor is time and so perhaps we should all take a moment to consider that, we are talking about Time.

To be clear the vas difference between us dying and a particle experiencing the equivalent is Temporal.

Any thoughts?

a reply to: Kashai
Einstein said this to Scrodinger in 1950, and it's because of decoherence that the cat is alive or dead inside the box regardless of any outside observation.

(See Schrodinger's cat on Wikipedia, ATS can't handle the special characters in the link)

Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.

Of course Einstein had never read ATS because it didn't exist yet when he was alive, but he wouldn't have been able to say that of some of the more extreme viewpoints on ATS who missed the point of the thought experiment and don't realize the obvious truth of what Einstein stated, that the cat is alive or dead regardless of any outside observation. It's really unfortunate some people have missed that obvious point so badly.

a reply to: Arbitrageur

If the cat is dead or alive prior to observation then the matter is temporal in relation to its status prior to observation.

You simply do not understand is that for Decoherence to occur, time is required. So therefore....

Surprising as it may be to most non-scientists and even to some scientists, Albert Einstein concluded in his later years that the past, present, and future all exist simultaneously. In 1952, in his book Relativity, in discussing Minkowski's Space World interpretation of his theory of relativity, Einstein writes:


Since there exists in this four dimensional structure [space-time] no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended, but yet complicated. It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.

Source



Any thoughts?

To be a clear a difference between a particle experiencing Decoherence and an organism having the same experience is a Temporal one.



Any thoughts?

originally posted by: Arbitrageur

originally posted by: neoholographic
Decoherence doesn't answer the question. When does the cat or the radioactive decay decide to be in one state or the other? How can it decide without an outside observer interacting with the information inside the box?

No outside observer is needed, just put a camera inside the box and the camera will record what happened before the box was opened.

Critique of "Quantum Enigma: Physics encounters Consciousness"

I share Steve Hawking’s impulse “to reach for my gun” (ref. [2], p. 120) whenever Schrodinger’s cat story is told. This cat story is notorious. It requires one to accept that a cat, which can be in innumerable different states, can be represented by a two-state wavefunction, a bit of nonsense which Schrodinger himself originated. However, a movie camera installed in the box containing the cat would record a cat that is alive until the unpredictable moment that the radioactive nucleus decays opening the bottle containing cyanide thus killing the cat.

With all due respect, that's just silly and has nothing to do with what I'm saying.

Of course if you put a camera in the box with the cat it will record a live cat because with a camera you don't have an isolated system in the box. You have a system that's being recorded by a camera.

Your post just proves my point.

If you put a camera in the box, then the camera is also in a state recording live cat/recording dead cat until a measurement occurs. Which recording the observer sees isn't decided until the outside observer looks at the camera footage.

When an observer interacts with the video he will see a cat get killed on the tape or a cat survive. Until that happens, the cat and the camera is a two state system. How can decoherence occur without an outside observer interacting with a state of the cat in the box?

People are just so blinded and scared of consciousness, as soon as they hear they want to say this has nothing to do with consciousness and they don't even know what consciousness is. How does that make any sense?

originally posted by: Kashai
"How can the wave function be physical? How can anything physical be in a pure state?"


What potential exist that the human condition has an effect upon the wave function?

How is Human and Animal DNA, as an example? In relation to its order. Interact in a system that conservative scientist claim is random, upon the grand scale of everything?

In reality Chaos theory is specific in relation to the conclusion, that perceived random systems, at the grand scale, are actually Non- Random.


Decoherence and Death seem to have something in common and what separates them perpetually seems to be Time.

Any thoughts?

For me, all of these quantum theories and dilemma, are examples of a growing continuity and resemblance to marriage, of QM and metaphysical narrative. These queries can speak to ideas and concepts like the Aether, Morphogenic Field, the Akashic Records, the Collective Unconscious, Holographic Reality, Electric Universe, etc., and how borrowing relevant nuts and bolts from such constructs, you can attempt to rationalize the questions, and begin the formulaic process.

"How can a wave be physical?"
"How can anything physical have a pure state?"

Well, look at all existence as an Etch-a-Sketch. A space filled with an abundance of building block particles knocking around. Some of the particles may bunch up to form shapes randomly (no such thing as random), but with a little intention guided through the controls, these "blocks" are brought into alignment, via a force invisible to the naked eye, to form structure. Now imagine if you surrendered handle of the controls, the structure would spontaneously disassemble, like a house of cards. This is a basic sketch (no pun intended), to addressing the paradox.

In the case of an Etch-a-Sketch, the forces at work are pretty apparent. Not so much when dealing with heavier existential complexities. Again, borrowing ideas from metaphysical theories, imagine the universe as a sphere of jello, that encapsulates a gossamer, nervous system, interconnecting ever fiber within the sphere, like s fetus in utero. Your physical actions reverb in all directions via the jello medium, and then also to a different degree and translation, the underlying neuro- lattice. These action produce their own signature and frequency which then travels harmonic pathways along both mediums, to queue shape. Remember, resonance has been discovered to manisfest into geometry in liquid mediums. This sculpt is a fractal, and relects on a quantum scale, forming the basic building blocks.

The resonance applied to both mediums can act as a compound, like an apoxy solvent, requiring constellation of alignments. This process could cover aspects of de/coherence. The human body does have frequency and an electrical charge. Electric pulses constitute human neurology. The human body can generate a low frequency EMF and static discharge. Ever have the hair stand up on your arm when you get emotionally excited? It's not the goosebumps lining up your ducks.

Can human intention via frequency/ resonance discharge manisfest inception and/ or annihilation? Coherence and Decoherence? Photons are thought to carry information. Can human intent tailor script through such controls and emissions? Is the basis for paradoxial state just a matter of alignment or the absence of? I can elaborate on the convergence of all of the aforementioned MP material, but that's a whole lotta bandwidth.

More questions, yep. But at least there's a plethora of metaphysical literature to cross reference, or reflect on, to translate into the QM arena.

a reply to: neoholographic

No you don't understand the camera will record the cats death even time stamp it if you want. You don't ever have to open the box. But if you do you will find a dead cat and a video with the time he died. Cats can not be in a superposition. This is a thought experiment only it's not a theory as some here suggest. What it tries to do and apatently fails with alot of people is to show you nothing is provable until observation. And without observation we cannot attain ant useful information about what's going on in the box until we interact with the closed system.

It's not difficult people try purposefully to make it so.
in any closed system like our box or a black hole nothing can be determined without observation and the act of observing changed the system from a closed state to an open state.

Here's some more about decoherence.

Decoherence does not claim to provide a mechanism for the actual wave function collapse; rather it puts forth a reasonable mechanism for the appearance of wavefunction collapse. The quantum nature of the system is simply "leaked" into the environment so that a total superposition of the wavefunction still exists, but exists — at least for all practical purposes[23] — beyond the realm of measurement.[24] Of course by definition the claim that a merged but unmeasurable wavefunction still exists cannot be proven experimentally.

While decoherence explains why a quantum system begins to obey classical probability rules after interacting with its environment (due to the suppression of the interference terms when applying Born's probability rules to the system), it does not explain what an observation actually is. Thus, it does not explain why the environment is seen to be in one definite state rather than in a superposition of states.

en.wikipedia.org...

This is what I call the MATERIALIST DILEMMA.

First, trying to use decoherence as a scientific theory to explain observed evidence is ASININE. It clearly shows the materialist are desperate. Science clearly shows Consciousness creates "reality" and the universe is fine-tuned for life.

In the face of this, materialist don't bring us anything scientific just fantasy.

If a person started a thread that said God created the universe, the first thing materialist would say is prove it. They would say show me the evidence.

Now they're faced with experiments that show materialism is a pipe dream, they're willing to accept a global superposition of the wave function THAT STILL EXISTS BUT IS BEYOND THE REALM OF MEASUREMENT. It still exists but cannot be proven experimentally.

Again, this is just nonsense and utter hypocrisy because as soon as someone talks anything materialist don't agree with, the first thing they say is that's not science or where's the experiment and now they're off on fantasy island because they want to hold on to their material beliefs.

Secondly, it begins to obey classical probability rules AFTER INTERACTING WITH IT'S ENVIRONMENT!! Exactly what I said. If you have a system in a box like a cat that isn't interacting with the outside environment, how can decoherence occur???? IT DOESN'T EXPLAIN WHAT AN OBSERVATION ACTUALLY IS.

originally posted by: neoholographic
Here's some more about decoherence.

Decoherence does not claim to provide a mechanism for the actual wave function collapse; rather it puts forth a reasonable mechanism for the appearance of wavefunction collapse. The quantum nature of the system is simply "leaked" into the environment so that a total superposition of the wavefunction still exists, but exists — at least for all practical purposes[23] — beyond the realm of measurement.[24] Of course by definition the claim that a merged but unmeasurable wavefunction still exists cannot be proven experimentally.

While decoherence explains why a quantum system begins to obey classical probability rules after interacting with its environment (due to the suppression of the interference terms when applying Born's probability rules to the system), it does not explain what an observation actually is. Thus, it does not explain why the environment is seen to be in one definite state rather than in a superposition of states.

en.wikipedia.org...

This is what I call the MATERIALIST DILEMMA.

First, trying to use decoherence as a scientific theory to explain observed evidence is ASININE. It clearly shows the materialist are desperate. Science clearly shows Consciousness creates "reality" and the universe is fine-tuned for life.

In the face of this, materialist don't bring us anything scientific just fantasy.

If a person started a thread that said God created the universe, the first thing materialist would say is prove it. They would say show me the evidence.

Now they're faced with experiments that show materialism is a pipe dream, they're willing to accept a global superposition of the wave function THAT STILL EXISTS BUT IS BEYOND THE REALM OF MEASUREMENT. It still exists but cannot be proven experimentally.

Again, this is just nonsense and utter hypocrisy because as soon as someone talks anything materialist don't agree with, the first thing they say is that's not science or where's the experiment and now they're off on fantasy island because they want to hold on to their material beliefs.

Secondly, it begins to obey classical probability rules AFTER INTERACTING WITH IT'S ENVIRONMENT!! Exactly what I said. If you have a system in a box like a cat that isn't interacting with the outside environment, how can decoherence occur???? IT DOESN'T EXPLAIN WHAT AN OBSERVATION ACTUALLY IS.

That's because you don't understand information. Information can be anything attained about a system. The only rule that causes people a problem is we cant observe more than 1 state at a time. IN QM I am restricted to either or the other properties don't change just because I can't see them. But this is where probabilities come into the math. In QM we can use probabilities to deduce outcomes independent of observation.

When we say something is in a superposition it simply means we can have multiple probabilities based on the information we obtained. Through QM we can use these probabilities to determine what will happen. This isn't some kind of mystic mumbo jumbo where the universe doesn't exist or with out us it wouldn't it was here long before we were and will be here long after us.
.

a reply to: neoholographic

Contemporary science is a "convenient" truth. Of course, compliance and omission bare down on immitable laws that can be irrefutably observed. But at the moment of condradition to continuity, the acedemic institutions fabricate voodoo mathematics, to either placate gross incompetence, or to more sinister ends, perpetuate a great deception. The ship is sinking and there aren't enough fat fingers to plug the leaks, comparable to a game of Whack a mole.We see these thin veneers riddled across all field study.

A slow, strip tease of disclosure had ensued, but with the ease of access to information through the internet, momentum became exponential. As the drips of true science are revealed in one facet, the integrity of another wanes. Reaching critical mass, no amount of spin doctoring and damage control can contain the immenent conflagration of truth.

Why is "observation" not quantified?! Because the whole framework of QM is Ad libbed! They don't even know themselves! They're a score of parrots in concert! Complexities are deliberately injected and infused into the science to confuse and misdirect. Welcome to modern day feudalism.

originally posted by: dragonridr

originally posted by: neoholographic
Here's some more about decoherence.

Decoherence does not claim to provide a mechanism for the actual wave function collapse; rather it puts forth a reasonable mechanism for the appearance of wavefunction collapse. The quantum nature of the system is simply "leaked" into the environment so that a total superposition of the wavefunction still exists, but exists — at least for all practical purposes[23] — beyond the realm of measurement.[24] Of course by definition the claim that a merged but unmeasurable wavefunction still exists cannot be proven experimentally.

While decoherence explains why a quantum system begins to obey classical probability rules after interacting with its environment (due to the suppression of the interference terms when applying Born's probability rules to the system), it does not explain what an observation actually is. Thus, it does not explain why the environment is seen to be in one definite state rather than in a superposition of states.

en.wikipedia.org...

This is what I call the MATERIALIST DILEMMA.

First, trying to use decoherence as a scientific theory to explain observed evidence is ASININE. It clearly shows the materialist are desperate. Science clearly shows Consciousness creates "reality" and the universe is fine-tuned for life.

In the face of this, materialist don't bring us anything scientific just fantasy.

If a person started a thread that said God created the universe, the first thing materialist would say is prove it. They would say show me the evidence.

Now they're faced with experiments that show materialism is a pipe dream, they're willing to accept a global superposition of the wave function THAT STILL EXISTS BUT IS BEYOND THE REALM OF MEASUREMENT. It still exists but cannot be proven experimentally.

Again, this is just nonsense and utter hypocrisy because as soon as someone talks anything materialist don't agree with, the first thing they say is that's not science or where's the experiment and now they're off on fantasy island because they want to hold on to their material beliefs.

Secondly, it begins to obey classical probability rules AFTER INTERACTING WITH IT'S ENVIRONMENT!! Exactly what I said. If you have a system in a box like a cat that isn't interacting with the outside environment, how can decoherence occur???? IT DOESN'T EXPLAIN WHAT AN OBSERVATION ACTUALLY IS.

That's because you don't understand information. Information can be anything attained about a system. The only rule that causes people a problem is we cant observe more than 1 state at a time. IN QM I am restricted to either or the other properties don't change just because I can't see them. But this is where probabilities come into the math. In QM we can use probabilities to deduce outcomes independent of observation.

When we say something is in a superposition it simply means we can have multiple probabilities based on the information we obtained. Through QM we can use these probabilities to determine what will happen. This isn't some kind of mystic mumbo jumbo where the universe doesn't exist or with out us it wouldn't it was here long before we were and will be here long after us.
.

I think you've misinterpreted what he is saying.

He wants to know what constitutes observation? Collection of information and data is a broad and simplistic anecdote.

Is the objects state determined by a particular, human observer? Does the state's potential result deviate, depending on different human observers? If the object is observed by a device, and never by human eye, has it technically been observed by definition? If so, what influence does mechanical collection of data infer on the subject's state? If data collected through mechanical means is read or interpretated by a human, does that qualify or influence the pending results?

Those are the variables I believe he is suggesting ratification. The point being this is just another vaporous pirouette, that exemplifies the wealth of pipe dreams, in light of discontinuity, ad absurdum.