How does uranium processing not cause desync?

[slippycheeze]

As far as I recall the only other pseudorandom event in the game is the cooldown between sending out of settlement biters (each time randomly between 4-30 minutes).
https://wiki.factorio.com/World_generator

I thought that terrain generation and resource generation also used pseudo-random numbers.

They do. I presume that ranger meant "during play" rather than during world generation. ...but, ultimately, the answer to any of those things is that the same input means the same output for the PRNG that Factorio uses, and they use an absolutely deterministic sequence for updating things, so every client consumes the same random number output at the same time.

[bobucles]

Don't forget to check out the FFFs. The devs have talked about many of the obstacles they have overcome in game development. You may find some things on keeping random number generation not so random.

I don't know enough about factorio under the hood to say how they did it, but I imagine the answer is something like "very carefully". As long as you track all the values involved, protect them from unusual influences and include them in the save data, it's a good starting point.

[MeduSalem]

Also computer can easily do random, just use the lowest bits from a camera feed. Enough quantum magic going on there.

Isn't that cheating like picking up random numbers from the lottery ? It feels to me like what would be random there would be the output of the feed, but that wouldn't require quantum magic.

I thought computers couldn't do true random, just non-predictable without so much time machine that it is considered safe enough to assume it look like random.

Various tricks with tiny unconnected capacitors and stuff work too, and modern CPUs and/or motherboard chipsets have high quality randomness generators too.

Is that using quantum mechanics ?

The former, I understand yes. The later I don't know, but something close enough. It *could* be an NSA planted PRNG with a known key/seed using cryptography to generate apparently random output, but probably not. Like, maybe 80 percent.

Ultimately, like the camera feed deal, there are lots of things where quantum randomness is available, and we keep finding more confirmation that you can't fully know a quantum system externally.

From what I have read into CPU design documents 15 years ago when I was studying the field as a hobby most of them use temperature differences in a chip to various degrees with sensors or with capacitors/transistors that react differently fast with decreasing/increasing local temperature.

At least as far as I know none of them do really use quantum mechanical effects for it. So if there's like only one such "sensor" per core and the load constant then with a constant temperature the results might eventually become predictable though.

That said with the smaller facbrication nodes quantum mechanical effects like quantum tunneling come into play and maybe that effect can be used or is already used by newer CPUs... like if through the temperature differences the size of the gate shrinks/grows and then more or less electrons tunnel to the other side and cause leakage currents and stuff like that which can probably be measured and used for calculation.

In my opinion a better approach if it isn't used already by modern multicore CPUs would be if the random number generator would pick temperatures from several locations on the chip and manipulate it with another second locale temp from the local core so that other cores have it harder to predict the random number that other cores might generate. With multicore CPUs they are never equal everywhere and the load is also more unpredictable with dozens of processes running across the cores.


But to be honest, even if it might be against the accepted phyiscs science knowledge I kinda believe in a fully deterministic universe... and that there is no true randomness on quantum level, just our bad understanding of it.

Enough off-topic for one day.

[slippycheeze]

Also computer can easily do random, just use the lowest bits from a camera feed. Enough quantum magic going on there.

Isn't that cheating like picking up random numbers from the lottery ? It feels to me like what would be random there would be the output of the feed, but that wouldn't require quantum magic.

I thought computers couldn't do true random, just non-predictable without so much time machine that it is considered safe enough to assume it look like random.

Various tricks with tiny unconnected capacitors and stuff work too, and modern CPUs and/or motherboard chipsets have high quality randomness generators too.

Is that using quantum mechanics ?

The former, I understand yes. The later I don't know, but something close enough. It *could* be an NSA planted PRNG with a known key/seed using cryptography to generate apparently random output, but probably not. Like, maybe 80 percent.

Ultimately, like the camera feed deal, there are lots of things where quantum randomness is available, and we keep finding more confirmation that you can't fully know a quantum system externally.

From what I have read into CPU design documents 15 years ago when I was studying the field as a hobby most of them use temperature differences in a chip to various degrees with sensors or with capacitors/transistors that react differently fast with decreasing/increasing local temperature.

At least as far as I know none of them do really use quantum mechanical effects for it. So if there's like only one such "sensor" per core and the load constant then with a constant temperature the results might eventually become predictable though.

That said with the smaller facbrication nodes quantum mechanical effects like quantum tunneling come into play and maybe that effect can be used or is already used by newer CPUs... like if through the temperature differences the size of the gate shrinks/grows and then more or less electrons tunnel to the other side and cause leakage currents and stuff like that which can probably be measured and used for calculation.

In my opinion a better approach if it isn't used already by modern multicore CPUs would be if the random number generator would pick temperatures from several locations on the chip and manipulate it with another second locale temp from the local core so that other cores have it harder to predict the random number that other cores might generate. With multicore CPUs they are never equal everywhere and the load is also more unpredictable with dozens of processes running across the cores.


But to be honest, even if it might be against the accepted phyiscs science knowledge I kinda believe in a fully deterministic universe... and that there is no true randomness on quantum level, just our bad understanding of it.

Enough off-topic for one day.

It is. Turns out the answer is "thermal is significantly involved, rarely the sole source, but it is complicated"; there is a bunch of information on the basic design out there on the web if anyone cares to know. Ivy Bridge is especially well documented, apparently. Thanks for encouraging me to go refresh my knowledge.

[Frightning]

The very notion of something being 'genuinely' random is itself questionable. Many examples people would put forth as 'random' are, in fact, quite deterministic, just that we usually lack accurate and complete enough information to predict it. I have wondered whether its possible to make a machine that would produce an output stream that is deterministic, but not identifiably so from a 'black box' perspective. (That is, suppose you were handed a deterministic black box that was asserted to produce random outputs; could you prove or show to some sufficiently high level of statistical confidence that it was deterministic?) Such a machine would produce an algorithmically random sequence. (https://en.wikipedia.org/wiki/Algorithm ... m_sequence).

[Adamo]

The very notion of something being 'genuinely' random is itself questionable. Many examples people would put forth as 'random' are, in fact, quite deterministic, just that we usually lack accurate and complete enough information to predict it. I have wondered whether its possible to make a machine that would produce an output stream that is deterministic, but not identifiably so from a 'black box' perspective. (That is, suppose you were handed a deterministic black box that was asserted to produce random outputs; could you prove or show to some sufficiently high level of statistical confidence that it was deterministic?) Such a machine would produce an algorithmically random sequence. (https://en.wikipedia.org/wiki/Algorithm ... m_sequence).

I've considered this the entire time I studied physics. The trick is to consider the phase space. A deterministic process will follow a set path through phase space, but a random one will only follow unique paths, never repeating, and a chaotic one (which is sort of partially-deterministic and partially-random, with extractable random elements -- e.g. weather) will follow unique paths that have a shared character (nearly-identical but not identical loops around a point, for example). The problem with chaos is that one can never be sure that the pattern won't repeat in some future. If it never repeats, it's a truly random process. But because we can only know this inductively, the possibility that it will repeat at some future time, proving it is not really random, always exists.

The only fundamental example I know that does not follow this pattern is quantum mechanics, where, for example, a pi meson decays into an electron/position pair, and they really do have a 50% chance each of having either spin up or spin down states. Within the context of the theory of quantum mechanics, there's no other information to know about the system to predict whether one or the other is spin up or spin down. They are in a superposition until the spin state is determined by a measurement, and so the result is truly a 50/50 coin flip. Of course, one might argue that a better theory exists beyond our understanding of quantum mechanics, and sure, OK, good luck with that. For now, that's the best random we know about in the universe, I'd say.

[BlueTemplar]

We are fairly sure by now that there are "no hidden variables" in quantum mechanics :
https://en.wikipedia.org/wiki/Bell%27s_theorem
(As an aside, I had the opportunity to learn this from a conference by Alain Aspect himself. Twice. About a decade apart.)

From what I have read into CPU design documents 15 years ago when I was studying the field as a hobby most of them use temperature differences in a chip to various degrees with sensors or with capacitors/transistors that react differently fast with decreasing/increasing local temperature.

At least as far as I know none of them do really use quantum mechanical effects for it. So if there's like only one such "sensor" per core and the load constant then with a constant temperature the results might eventually become predictable though.

That said with the smaller facbrication nodes quantum mechanical effects like quantum tunneling come into play and maybe that effect can be used or is already used by newer CPUs... like if through the temperature differences the size of the gate shrinks/grows and then more or less electrons tunnel to the other side and cause leakage currents and stuff like that which can probably be measured and used for calculation.
[...]

The whole semi-conductor behaviour is treated quantum-mechanically these days (even though Plank's constant h does not directly intervene) :
https://en.wikipedia.org/wiki/Semicondu ... conduction

Filling of the electronic states in various types of materials at equilibrium. Here, height is energy while width is the density of available states for a certain energy in the material listed. The shade follows the Fermi–Dirac distribution (black = all states filled, white = no state filled). In metals and semimetals the Fermi level EF lies inside at least one band. In insulators and semiconductors the Fermi level is inside a band gap; however, in semiconductors the bands are near enough to the Fermi level to be thermally populated with electrons or holes.

And then the presence of electrons/holes in the bands is going to depend on temperature :

So a semi-conductor at room temperature might become an insulator when cooled,
And an insulator at room temperature might become a (semi-)conductor when heated.

Ditto for thermal noise in electronics :
https://en.wikipedia.org/wiki/Johnson%E ... anck's_law

[Adamo]

We are fairly sure by now that there are "no hidden variables" in quantum mechanics :

Technically, Bell's Theorem only tests whether *local* hidden variables exist: that is, variables for interactions that propagate at or slower than the speed of light in a vacuum. We have never ruled out non-local hidden variables. But I don't claim to know where the next theory will come from. Certainly, at this time, any hidden non-randomness behind the predicted random behaviour of quantum systems is beyond our ability to detect in a coherent way, which is in agreement with the rest of what you said.

[mmmPI]

We are fairly sure by now that there are "no hidden variables" in quantum mechanics :

Technically, Bell's Theorem only tests whether *local* hidden variables exist: that is, variables for interactions that propagate at or slower than the speed of light in a vacuum. We have never ruled out non-local hidden variables. But I don't claim to know where the next theory will come from. Certainly, at this time, any hidden non-randomness behind the predicted random behaviour of quantum systems is beyond our ability to detect in a coherent way.

Isn't that the whole deal of finding "graviton" if they exist in LHC ?

Since gravity's interaction propagate faster than the speed of light, theorically there can't be any particle that is the carrier of the information.

Either we find graviton, they go faster than speed light => that's the fantasm of so many people from information theory and this contradict physics as we know it.

Or we admit gravity is "non local" ?

Does that makes sense ? is that the implication of bell's theorem or am i lost ? x)

(learning from internet only so please send me link if i obviously need some basics).

[Adamo]

We are fairly sure by now that there are "no hidden variables" in quantum mechanics :

Technically, Bell's Theorem only tests whether *local* hidden variables exist: that is, variables for interactions that propagate at or slower than the speed of light in a vacuum. We have never ruled out non-local hidden variables. But I don't claim to know where the next theory will come from. Certainly, at this time, any hidden non-randomness behind the predicted random behaviour of quantum systems is beyond our ability to detect in a coherent way.

Isn't that the whole deal of finding "graviton" if they exist in LHC ?

Since gravity's interaction propagate faster than the speed of light, theorically there can't be any particle that is the carrier of the information.

Either we find graviton, they go faster than speed light => that's the fantasm of so many people from information theory and this contradict physics as we know it.

Or we admit gravity is "non local" ?

Does that makes sense ? is that the implication of bell's theorem or am i lost ? x)

(learning from internet only so please send me link if i obviously need some basics).

No. Gravitons are predicted to propagate with the speed of light in a vacuum, since it is the quantum of the gravitational field, which also propagates with the speed of light in a vacuum. So this means no information carried by the graviton is predicted to violate Bell's Theorem.

[Oktokolo]

The very notion of something being 'genuinely' random is itself questionable.

Quantum mechanical effects have been mentioned. They are assumed to be genuinely (without any quotes!) random by todays scientific community.
I don't like that either. Looks like a sloppy "engine optimization". But seems like the universe is indeed rolling dice a lot...

I have wondered whether its possible to make a machine that would produce an output stream that is deterministic, but not identifiably so from a 'black box' perspective.

That is easy in theory and practice:
1. Define any number your first "random" number.
2. Feed the current "random" number into a cryptographically secure one-way hash function and use teh result as your new current "random" number.
3. Goto 2. for more "random" numbers.

Example of well-suited state-of-the-art cryptographically secure one-way hash functions would be the functions of the SHA3 (Keccak) group.

[Koub]

[Koub] We're now very seriously off topic. I love the subject of quantum physics and all the oddities, but it has nothing to do with the initial question. If the off-topicness continues, I'll just lock the thread.