[crazydoggers]

Even in some hypothetical void, you’d have the quantum vacuum state. So via quantum mechanics you can have particles pop into and out of existence, providing you with a way to gauge the passing of time even in otherwise completely empty spacetime.

[mojomark]

> Even in some hypothetical void, you’d have the quantum vacuum state.

One could imagine that beyond some cosmological horizon the rules of physics as we know them break down and there is no zero point energy.

Normally you think of the rules of physics breaking down at a singularity point, say, beyond a black hole's event horizon or at the start of the big bang. If you subscribe to the idea that the big bang event shaped the laws of physics we know, then beyond the horizon of the "expanding" big bang, those laws won't necessarily apply.

I put expanding in quotes because I subscribe to the idea of a holographic universe. I like to think that while the universe may appear to be expanding at an accelerated pace to us, you can also think of our universe as shrinking within a fixed boundary. (Fixed relative to what?)

For example, imagine a 2D holographic plate (our true plane of existence), through which you can view an image of a 3D virtual object (our perceived plane of existance). Now imagine the interference pattern on that plate is dynamic and increases in entropy, defining and arrow of time for the objects in the 3D virtual image. The plate doesn't change size, but the complexity of the interference pattern increases, creating increasingly finer and finer details, such that from the perspective of a virtual object, everything appears to be expanding, but from an outside observer's perspective the holographic image appears to be shrinking as the entropy increases.

[jakeinspace]

I'm no physicist, but I wasn't sure whether the goings on of quantum mechanics (virtual particles) in a vacuum is sufficient for entropy to occur. It seems like a timeless process, with forward and backward interactions equally likely. Of course, if the underlying fields are slowly changing with time, then that would likely be entropic.

[crazydoggers]

Good point. But I think there is a distinction between measuring entropy and the passing of time. From my understanding entropy provides the arrow of time, meaning the non symmetrical past vs future. Whereas time by itself could still be measured as flowing, though whether forward or backward you may not be able to determine.

Obviously if something like a human brain was there to observe things, you'd have the entropy of your neurons to be sure of the direction as well. =D