[pockmarked19]

> entire concept of time

“Entire” concept is stretching it, causality and entropy are not man made.

If you want to look at ideas people made up that have way too much influence on our lives, you need look no further than your wallet.

[_hark]

Entropy is not absolute!

The entropy of some data is well-defined with respect to a model, but the model choice is free. I.e. different models will assign different entropy to the same data.

And how do we choose a model...? Well, formally by minimizing the information needed to describe both the model and data (the sum of model complexity and data entropy under the model) [1]

You might argue that's all too information-theoretic and in physics there simply is an objective count of the state-space, a maximum entropy, and so on. Alas, there is not even general consensus on whether there is a locally finite number of degrees of freedom.

[1]: https://en.wikipedia.org/wiki/Minimum_description_length

[beagle3]

But it is closer to absolute than you make it sound here. There are information theoretic models which are “universal” with respect to a class; that is, they are essentially as good as any in that class, for every individual case you apply - even if different cases are best described by distinct models from that class.

E.g. the KT estimator is, for each individual Bernoulli sequence, as good as the best Bernoulli model for that sequence with at most 1/2 but difference (independent of sequence length)

It is undecidable/uncomputable, and only well defined up to a constant, but you have a “universally universal” model - Kolmogorov complexity. In that sense, entropy IS an absolute.

[viccis]

The entire concept of causality and entropy as something that happens in a linear progression at approximately the same rate is 100% a concept that is "made up" insofar as it is, as Kant would put it, the process of apprehending a sequence of sensibilities into a schematized understanding of the objects around us. Cause and effect are real (and don't require empirical understanding), but only viewing objects in the space around us as partial impressions that are contingent on that specific time is the "man made" part of subjectivity.

So a better way to put it is that time is real, but only as it relates to our perception. And that is always subjectively contingent. The concept of "time" outside of any subjective perception doesn't really make sense. Even if you're purely limiting it to "causality", then you're going to run into a host of issues if you think you can order causal interactions into a linear "time"line.

[fooker]

If you could prove the bit about causality you'll get a Nobel prize or two.

As that would definitively declare that there's no going back in time, there's no negative mass, and perhaps philosophically--theres no free will.

[dmos62]

For all we know, causality (or simply put - the past) is simply a feature of being, i.e. the product of now, as opposed to now being the product of causality. We think that we transition from now to a different now through causality, but maybe we transition through some other means and a continuous past is simply a byproduct.

[y33t]

I'd say causality and entropy are contingent on the (very compelling) assumption that time is real. We could be Boltzmann Brains, or something even weirder. Do I believe that the world is terribly different from what it appears to be? No, but ultimately our perceptions of the world are merely representation held in our minds.

[TheOtherHobbes]

We could be Boltzmann Brains on drugs.

Or worse.

Presumably the probability of a brain appearing as a disordered psychiatric monster is far higher than the probability of arriving as an Earth-normal tenured cosmologist.

[whatnow37373]

> causality and entropy are not man made

Given that we fundamentally depend on our own, very human, sensory and cognitive apparatus to make any kind of judgement I have a hard time imagining a proof or even a convincing argument of this without falling back on “it’s obvious” (etc).

Yes, I am being obtuse. Sorry about that. Just for the record.