Those are not statements about physics though. They just employ some of the lingo.

Physics depends on metaphysics.

I really do hate to start a reply with a flat-out "no", but in this case it's warranted, sorry to say. There are two ways of looking at this, and none of them permit this conclusion:

Physics as a science does not depend on metaphysics in any way. When a physicist does his/her work, it does not require the invocation of supernatural principles. While speculation and hypotheses are essential to the scientific process because they drive further exploration, metaphysical arguments on the other hand are just postulates about the nature of reality - and they are in most cases either in direct conflict with observational data, or designed to be un-disprovable.

Now for physics, as in the actual universe. This doesn't depend on metaphysics either. In fact, it's the other way around. As the universe develops, intelligent life emerges, humans in our case. These humans can then invent religion and the supernatural. The physical world came first.

Proper metaphysics is very limited and has nothing to do with the supernatural. When physicists do their work they rely on such concepts as existence, identity, causality, the relation of consciousness to these. That's metaphysics.

To state that "the physical world came first" is to assert the primacy of existence in opposition to the primacy of consciousness (e.g. Descartes) -- that's correct and that's metaphysics.

We went off on a tangent there, I suspect we've already bored everyone else in this thread to death ;)

I want to close with the observation that whether you're aware of it or not, you're talking about supernatural claims that have been postulated without any scientific evidence.

To make this distinction between the words metaphysical and supernatural feels a bit similar to fundamentalist Christians who assert that they're not religious - a phenomenon which I suspect happens for the same reasons: because they believe their faith represents the "truth" about the universe, it doesn't count as a religion. But to everyone else, it still does.

Are you claiming there is no evidence for the concept of causality? and that any discussion of existence or identity is the province of faith, not reason? If some people replace metaphysics with religous idiocy, that does not invalidate the field as such -- the same applies to all fields of rational inquiry, from physics to psychology.

I subscribe to the evidence of the senses, logic, and science. If you think any discourse about such topics belongs to the supernatural and religious, that's your problem, not mine.

The relative nature of time is kind of what Mercati is working with (I think). He's trying to describe entropy using only a self-relative framework. That is, without using fixed metrics like temperature or distance in an absolute frame of reference.

There was another article about this on HN previously.[1]

Why is it that the causal relations existing as a result of elementary forces spreading from one particle to another only ever change in one direction in time? When you map the space of the universe onto two dimensions, you see the effects of forces radiating from their origins as circles. But when you reduce all of space to one dimension and add another dimension of time, those forces only appear as cones, all pointing the same direction. What is stopping the forces from flowing backward, or even sideways in time? The math we're using gives no indication why this is the case. That's what has physicists scratching their heads.

[1] https://news.ycombinator.com/item?id=8561654