Update

determinism.md

@@ -4,6 +4,8 @@
 
 Deterministic system (such as a computer program or an equation) is one which over time evolves without any involvement of [randomness](randomness.md) and probability; i.e. its current state along with the rules according to which it behaves unambiguously and precisely determine its following states. This means that a deterministic [algorithm](algorithm.md) will always give the same result if run multiple times with the same input values. Determinism is an extremely important concept in [computer science](compsci.md) and [programming](programming.md) (and in many other fields of science and philosophy).
 
+Determinism is also a **philosophical theory** and aspect of physics theories -- here it signifies that our Universe is deterministic, i.e. that everything is already predetermined by the state of the universe and the laws of physics, i.e. that we don't have "[free will](free_will.md)" (whatever it means) because our brains are just machines following laws of physics like any other matter etc. Many normies believe [quantum physics](quantum.md) disproves determinism which is however not the case, there may e.g. exist hidden variables that still make quantum physics deterministic -- some believe the Bell test disproved hidden variables but again this is NOT the case as it relies on statistical independence of the experimenters, determinism is already possible if we consider the choices of experimenters are also predetermined (this is called [superdeterminism](superdeterminism.md)). [Einstein](einstein.md) and many others still believed determinism was the way the Universe works even after quantum physics emerged. { This also seems correct to me. Sabine Hossenfelder is another popular physicist promoting determinism. ~drummyfish } Anyway, this is already beyond the scope of technological determinism.
+
 [Computers](computer.md) are mostly deterministic by nature and design, they operate by strict rules and engineers normally try to eliminate any random behavior as that is mostly undesirable (with certain exceptions mentioned below) -- randomness leads to hard to detect and hard to fix [bugs](bug.md), unpredictability etc. Determinism has furthermore many advantages, for example if we want to record a behavior of a deterministic system, it is enough if we record only the inputs to the system without the need to record its state which saves a great amount of space -- if we later want to replay the system's behavior we simply rerun the system with the recorded inputs and its behavior will be the same as before (this is exploited e.g. in recording gameplay demos in video [games](game.md) such as [Doom](doom.md)).
 
 Determinism can however also pose a problem, notable e.g. in cryptography where we DO want true randomness e.g. when generating [seeds](seed.md). Determinism in this case implies an attacker knowing the conditions under which we generated the seed can exactly replicate the process and arrive at the seed value that's supposed to be random and secret. For this reason some [CPUs](cpu.md) come with special hardware for generating truly random numbers.
@@ -18,8 +20,6 @@ Even if we're creating a program that somehow works with probability, we usually
 
 In theoretical computer science non-determinism means that a model of computation, such as a [Turing machine](turing_machine.md), may at certain points decide to make one of several possible actions which is somehow most convenient, e.g. which will lead to finding a solution in shortest time. Or in other words it means that the model makes many computations, each in different path, and at the end we conveniently pick the "best" one, e.g. the fastest one. Then we may talk e.g. about how the computational strength or speed of computation differ between a deterministic and non-deterministic Turing machine etc.
 
-Determinism is also a philosophical theory that says our Universe is deterministic, i.e. that everything is already predetermined by the state of the universe and the laws of physics, i.e. that we don't have "free will" (whatever it means) etc. Many believe [quantum physics](quantum.md) disproves determinism which is however not the case, there may e.g. exist hidden variables that still make quantum physics deterministic. Anyway, this is already beyond the scope of technological determinism.
-
 **Determinism does NOT guarantee [reversibility](reversibility.md)**, i.e. if we know a state of a deterministic system, it may not always be possible to say from which state it evolved. This reversibility is only possible if the rules of the system are such that no state can evolve from two or more different states. If this holds then it is always possible to time-reverse the system and step it backwards to its initial state. This may be useful for things such as [undos](undo.md) in programs. Also note that even if a system is reversible, it may be computationally very time consuming and sometimes practically impossible to reverse the system (imagine e.g. reversing a cryptographic [hash](hash.md) -- mathematical reversibility of such hash may be arbitrarily ensured by e.g. pairing each hash with the lowest value that produces it).
 
 **Is [floating point](float.md) deterministic?** In theory even floating point arithmetic can of course be completely deterministic but there is the question of whether this holds about concrete specifications and implementations of floating point (e.g. in different programming languages) -- here in theory non-determinism may arise e.g. by some unspecified behavior such as rounding rules. In practice you can't rely on float being deterministic. The common float standard, IEEE 754, is basically deterministic, including rounding etc. (except for possible payload of [NaNs](nan.md), which shouldn't matter in most cases), but this e.g. doesn't hold for floating point types in [C](c.md)!