Energy conservation follows from Noether's theorem and time translational symmetry. This doesn't hold in general for an arbitrary space-time. In fact, it holds for a very specific subset (static spacetimes) of which our universe is not one of them.

Related: "Energy is Not Conserved" by Sean Carroll [1].

[1] https://www.preposterousuniverse.com/blog/2010/02/22/energy-...

As another complete layman just pooling my intuition:

Relatively more or less dense "things" (to each other) will always generate positive curvature of spacetime. What you want is relatively less dense area than vacuum in another region of space, since vacuum is (for now) what we constitute as (somewhat) flat.

That's what Casimir effect tries to accomplish: define a small enough region of spacetime where some larger quantum fluctuations don't have enough space to happen, thus lowering its energy below vacuum.

Since the idea is to define small enough space-like interval in spacetime to curb some energies off, could defining small enough time-like interval help the same purpose, multiplying the former?

Thanks, this makes a bit more sense to me now, but let's figure out if I understood it correctly:

The Casimir effect is about creating a spacetime "corset" so to speak, that is so tight that even the regular quantum fluctuations don't have "enough room to pass", so they "almost freeze", and when they "come out on the other end", they could for example break or delay entanglement?

On the other hand I think your assumption about the time aspect might be correct as we are talking about spacetime after all. The biggest issue might be that measuring time deltas might be harder than space deltas?

I don't think the Casimir effect is utilizing some medium flowing between the plates. Its not about a quantum fluctuation freezing as it passes trough the passage between the plates. Its rather that the quantum fluctuation comes into existence and disappears at random point in a vacuum, how often depends on the energy of the vacuum. When you put two plates really close together, there is not enough space for the quantum fluctuation to materialize, as it's wavelength is bigger than the gap. That way you limit the amount of those fluctuations materializing between the plates, and because there's less of them, there should be less energy than in unobstructed space, even vacuum. Thus negative energy, because its less than the 0 we assume for vacuum.

Regarding working with time-interval, it might as well just be the opposite: minimize space-interval and maximize time-interval for maximum effect. It's just wild guesses at my side. But minimizing time-interval should be trivially doable by just slinging the plates past each other at high speed.

LOL, looks like one gets seriously downvoted for mental freewheeling on HN... I did not see that coming, especially since I added a disclaimer.

Anyway, thanks for taking the time to try to explain this to a total layman, but I'll defer engaging into subject matters that I never heard about before; lesson learned...