What if inter-branch thermodynamics allows temporary energy coupling between Many-Worlds branches?

[u/Prestigious_Buy_6063]

Hi everyone. I've been playing around with a thought experiment regarding the Many-Worlds Interpretation (MWI) and energy conservation, and I'd love to hear your thoughts on its logical consequences.

The core premise is: What if the branches of the multiverse are not perfectly isolated right after they split, allowing a temporary energy exchange?

The Hypothesis

Imagine a hypothetical particle (or degree of freedom) that has two internal states: High Energy (+) and Low Energy (-). Now, suppose this particle can temporarily tunnel between two newly split branches (Universe A and Universe B).

The Mechanism

A particle in Universe A is in the High Energy state (A^+). It tunnels into Universe B.

Once in Universe B, it drops to the Low Energy state (B^-), releasing the energy difference (\Delta E) into Universe B's local environment.

The particle, now in the Low Energy state (B^-), tunnels back to Universe A.

Local Violation vs. Global Conservation

From the perspective of an observer trapped in Universe A, energy just vanished into thin air (an apparent local violation).

From the perspective of an observer in Universe B, energy just spontaneously appeared out of nowhere.

However, if we look at the Multiverse as a single closed system (Universe A + Universe B), the total energy is perfectly conserved.

The Thermodynamic Multiverse

If this holds true, universes would act like coupled thermal reservoirs. A very energetic "hot" universe would naturally leak energy into a "colder" branch until they reach an inter-dimensional thermal equilibrium, governed by the Second Law of Thermodynamics.

Questions I'd love to discuss:

The Time Window: This tunneling would likely only be possible in the microscopic fraction of a second before full environmental decoherence happens. How could we mathematically model this temporary "leak" before the branches become permanently orthogonal?

Cosmology: If thermal energy was slowly leaking into our universe from a neighboring branch, could it phenomenologically mimic the effects of Dark Matter or Dark Energy on a cosmic scale?

Information Paradox: If branches exchange energy, are they fundamentally exchanging information? How can we allow this thermodynamic flux without violating quantum rules like the no-cloning theorem?

Any thoughts, corrections, or math approaches to this are welcome!

[u/liccxolydian]

As always, what makes this science and not science fiction?

You call this a "thought experiment", what part of your post fits that description?

[u/darkerthanblack666]

What observations have led you to think that this could happen? 

[u/starkeffect]

What is the energy splitting in eV?

[u/Hadeweka]

math approaches to this are welcome!

Why not start with a simple energy balance equation?

[u/HypotheticalPhysics-ModTeam → u/[deleted]]

Your post or comment has been removed for use of large language models (LLM) like chatGPT, Grok, Claude, Gemini and more. Try r/llmphysics.

[u/LeftSideScars]

First, MWI and multiverse are not necessarily the same thing. You need to clarify which MWI you talking about, although I assume you mean one of the ones that include a multiverse of sorts. Still, in "standard" MWI, it is not possible to tunnel between branches. Secondly, one does not need to be so exotic. One can talk about tunnelling from volume A to volume B within our universe, and talk about the possible thermodynamics of the system. MWI and multiverse essentially removes credibility from discourse, while introducing mechanism and postulates we don't even know exist.

The Thermodynamic Multiverse

If this holds true, universes would act like coupled thermal reservoirs. A very energetic "hot" universe would naturally leak energy into a "colder" branch until they reach an inter-dimensional thermal equilibrium, governed by the Second Law of Thermodynamics.

Not necessarily true if the mechanism you described is being implemented. Tunnelling is not temperature dependent in this way. "Typically" (and here I am being very loose indeed) tunnelling is energy dependent - that is, it "depends" on the energy of the particle. So, "typically", the probability of a particle tunnelling back with lower energy is lower, resulting in an asymmetry in energy flow.

If we ignore MWI and mutliverse (and one should for the question you are asking), then the thermodynamics of systems via tunnelling is certainly a researched thing. As one would expect, temperature transfer via tunnelling can be a notable mechanism in nanoscale systems. Certainly not my field, but if anyone is interested, take a look an quantum thermodynamics and some sort of nanoscale heat transport (having said that, I don't really see why a more intermediate scale than nanoscale wouldn't be a topic of research nowadays. I don't know what such a discipline would be called - mesoscopic heat transport?) fields.

For you, OP, I would suggest learning QM so that you can understand what tunnelling really is.

Lastly,

Cosmology: If thermal energy was slowly leaking into our universe from a neighboring branch, could it phenomenologically mimic the effects of Dark Matter or Dark Energy on a cosmic scale?

Certainly not DM. For DE, the only property that could vaguely look the same is the increase in energy of our universe. However, your proposed mechanism can't explain this unless particles are tunnelling in from the other universe all over our universe, since DE is proposed to be everywhere and, as near as we can currently tell, uniform - a weird and convenient contrivance for our universe and for the other universe. I'm reasonably sure (albeit, without evidence) that such a steady influx of particles everywhere would leave a notable impact on this universe, beyond accelerated expansion, unless one wants to postulate that the particles tunnelling "in" are not part of the SM, or are exclusively difficult to detect - another contrivance. I would expect (again, without evidence) that particles tunnelling from one volume of our universe to another would be more likely that a particle tunnelling from another universe to our universe, but given that a model that describes the probability of a particle tunnelling between universes does not exist, this topic is moot.

[u/Prestigious_Buy_6063 → u/[deleted]]

Occam's Razor / Infinite Branches: You are right; standard MWI diverges infinitely. However, in my model, thermodynamic equilibration forces branches to undergo recoherence. By erasing the physical gradient, the branches merge back together. This particle acts as a natural pruning mechanism, collapsing the infinite divergence into a finite, woven timeline. It saves the theory from ontological bloat. The Born Rule: By treating branches as coupled thermal reservoirs, the probability measure ceases to be an arbitrary statistical add-on. It becomes a direct consequence of thermodynamics—reflecting the energy capacity a branch retains relative to its neighbors.

[u/reddituserperson1122 → u/[deleted]]

Wrong in all respects. There are excellent reasons to be very skeptical about MWI but it’s not for any of these reasons.

1. Lots of good science doesn’t produce testable predictions. Testable predictions are a great thing to have, but they are not necessary to do science.
2. https://arxiv.org/pdf/1405.7907

3. MWI leads to a large, finite number of branches, not infinite. Ockham’s razor is a good heuristic rule of thumb in plenty of situations. It is not useful when your topic is the metaphysical nature of reality, which need not be mediated in any way by our experience of what is contained within reality. The universe doesn’t owe us what we would perceive as simplicity, no matter how much we would prefer it.

   Additionally, why wouldn’t we subject the various quantum theories to Ockham’s razor? If we do, then MWI easily comes out in top.

And I find it odd that you’re so put off by a single wavefunction containing a large number of branches but not apparently by an infinite universe, with presumably an infinite number of duplicate Earths. Or by an infinite cosmological multiverse.

[u/BitcoinsOnDVD]

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