A measurement far after the double slit experiment shows the entire life/path(indirectly) of the particle is known via state. The final panel is the exception because the wave will collapse, what matters is what a wave/particle is while in flight.
It's either a wave OR a physical particle(local). It's possible for a wave to make it from point A to B without being measured before the final screen. That's why it shows fringes. You don't get quantum weirdness (Superposition (not talking about superposition of states), Entanglement, Tunneling) events when it's a particle. They don't experience weirdness after decoherence. Only cohered waves are allowed weirdness events.
There is a clear difference of what a particle is with decoherence. The quantum field is responsible for uncertainty and still has influence on physical particles ..making them wobble for fringe tests, in this case it isn't fringe, you are looking at uncertainty. You don't decohere a wave (with a detector) and then expect to find fringes afterwards.
Measurements done after the fact (hitting the final panel) have no barring on what the particle was in flight.
The quantum field doesn't use time from spacetime. Unobserved quantum waves do not age. This is how the quantum field knows if a state was triggered in the particles life/path before launching it. This is the core of what measurement/observation is.
A particle/wave will be what it is throughout the flight. No Duality.
This is the gateway to the Unified Theory. Physical particles go with GR, Unobserved Quantum Waves go with the Quantum Field. Spacetime is separate from the Quantum Field. There is a quantum/classical boundary around the mass of a virus. Objects above this line are automatically decohered.
Unobserved Matter-Waves do not decay. Also, physical particles (observed) do not tunnel. The math involves a "retarded" Schrodinger equation solution with a damping factor that causes the state vector to not be constant. It is an observable, since it is a hermitian operator and its eigenvectors form a basis of the state space. Hooray for dissipative behavior! This behavior is what prevents an observed particle from tunneling. Unobserved quantum waves are immune to forces when trying to tunnel ..physical particles are not. There are constants involved that are not touched by forces when the object is waves.
The delayed choice quantum eraser also shows the entire path of the particle is known before being launched.
Future observed matter-waves decohere before they start moving because their momentum direction triggers decoherence. (Decay of coherence) http://othes.univie.ac.at/30192/1/2013-07-28_0747803.pdf
Observation isn't possible without time from spacetime https://arxiv.org/pdf/1305.3591.pdf
"Okay, perhaps you could define for me exactly what it means to decohere a particle?"
Measure it in a way that allows it to continue on its path to a final panel where the wave collapses
"But if the wave hasn't collapsed into a particle yet (using your terms) then how does it have a "path"?"
If a wave is going to decohere in its path ..it won't be a wave from the very beginning.
"So if a wave ever collapses into a particle then it was never a wave to begin with?"
That's what I said in the OP
"Can you explain what a quantum field is? Or more specifically, can you explain how the definition of a field doesn't completely contradict your statements like "The quantum field doesn't use time from spacetime" or "Unobserved quantum waves do not age"?"
The Quantum Field is the group of fields that run on fluctuations.
Something is weird with time in the quantum field. It is connected to the trigger of something gaining a physical state. The age part is said because coherent matter-waves do not decay ..it's only after they decohere and become physical do they age.
"The Schrodinger equation describes how wave functions "age". It applies even before decoherence."
Not the same type of "age". Everything about waves is artificial. I think they are holograms/virtual, they hold quantum information. If an unobserved matter wave can tunnel ..so can its mass.
"Where does the dissipative behavior come from?"
The behavior is built into the "retarded" function https://arxiv.org/pdf/quant-ph/0206117.pdf
"If quantum waves are immune to forces, then why do electron orbitals in atoms--which are most definitely waves--exist?"
They don't have a point A to B ..they don't have a starting point
They are unreal/virtual/holographic waves
oh any by the way, Dark Matter is quantum waves that can never be decohered.
I don't agree with "A measurement far after the double slit experiment shows the entire life/path of the particle is known via state."
The path is known indirectly. It's a natural process, there isn't anything to "know" but a state change will do the swap preemptively.
I also read in the op that time does not influence quantum states until observation and stated as observation being the catalyst of collapse?
no, decoherence isn't a collapse. Decoherence is a measurement that leads to a physical state. The final panel of a experiment is wave collapse ..and it doesn't influence the granting of physical states.
What do you know about Quantum Gravity?
Gravity isn't a force, it's the bending of spacetime. There is a required amount of mass to interact with it.
The paper you linked doesn't mention tunneling, so where do you get that it describes particles that don't tunnel?
I've been searching for a way to send a decohered wave into a potential well ..this is the only formula that offers a way to do it. Retarded has damping and a state reduction. I needed less frequency oscillation for decoherent waves. And the extra bonus of Unobserved quantum waves being immune to forces (the constants) ..physical particles are not.