Computer Science Stack Exchange
Computer Science Stack Exchange

Questions tagged [physics]

All issues relation physics and computation theory (excluding computational hardware or use of computers in physics). May include, for example, analog computing, reversible computing, physical analysis of computability (Church-Turing thesis).

Issues related to quantum-computing should rather use that tag.

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Is there a connection between the halting problem and thermodynamic entropy?

Alan Turing proposed a model for a machine (the Turing Machine, TM) which computes (numbers, functions, etc.) and proved the Halting Theorem. A TM is an abstract concept of a machine (or engine if you like). The Halting Theorem is an impossibility…
Nikos M.
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Can one build a "mechanical" universal Turing machine?

This question connects different disciplines so it's awkward to choose a SE site for it, but I'll go with this one because here (I hope) the shared culture will make information transfer easier. So computers as we know them use electricity and I…
acupoftea
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12
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Undecidable problems limit physical theories

Does the existence of undecidable problems immediately imply the non-predictability of physical systems? Let us consider the halting problem, first we construct a physical UTM, say using the usual circuit based construction. Then there can be no…
user2663116
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What is the difference between luma and luminance?

I understand the following (correct me if I'm wrong): Statements Luma as the weighted sum of RGB gamma corrected components, but luminance is the weighted sum of RGB linear components. The gamma correction has two forms: gamma compression and…
winnie99
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Learning dynamics

I recently learned about Q-learning, a reinforcement learning technique that directly estimates the expected value of taking an action in a state. I'm wondering if there exists techniques to do "dynamics learning", in order to estimate the dynamics…
Robz
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Could an NP-hard problem have a mechanical or physical solution method?

Is there any NP-hard problem that we can find a mechanical "polynomial time" solution to? For example, suppose we construct a graph out of something physical, e.g. we have have pipes through which we can move water. If this pipe system was suitably…
user34391
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Reference Request: Overlaps between complexity theory and dynamical systems?

Per Wikipedia: In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in a geometrical space. Examples include the mathematical models that describe the swinging of a clock pendulum, the…
Fraïssé
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Patriot Missile Software Bug (Range Gate Calculation)

Okay so I was reading about the Patriot Missile Software Bug, where to calculate the predicted range gate the missile system relied on the time keeping, however it would convert the whole/integer time number it stored (say 3600000) to 24 bit…
coldsrc
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What is the most efficient non-quantum computer that can be built?

I am aware of two models of computation, neither of which describe the optimal computer we can build: Turing machine: This model is not optimal due to the head having to travel a large distance taking time $O(n)$ to access memory at address…
user171322
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Solving the maximum flow problem in the real world

Is it possible to solve the maximum flow problem in the real world, ie. using water running through physical pipes? So you would have a tap at the source node, pipes of various diameter (depending on their capacity) connecting nodes and a sink at…
Dmitry Kamenetsky
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Evenly Spaced Points On Smooth Surface

I want to space points evenly (i.e. maximizing minimal distance between two points) on some smooth surface $S\subseteq\mathbf{R}^n$ (usually $n=3$), where I have a projection operator $p:\mathbf{R}^n\to S$ which approximates the closest point on the…
fweth
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Potential General Model of Computation with Physics?

I posted a question about a month back regarding the significance of Turing machines (relative to other models of computation). In that post, I mentioned vaguely some conversion between an input string and a physical system as a model of…
Alex
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Research in realtime computational physics?

I am aware that there is a considerable amount of interest in computational mechanics for simulation of cloth, hair and other elastica, particularly for animation films. The methods developed by groups in computational mechanics (that I am aware of)…
visualiser
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Finding orders in raw Echelle spectrum frame

Being new in this forum, would like to get some hints for solving the following problem. In the attached frame the short vertical line segments are emission lines. As can be clearly seen, these lines are grouped in horizontal curved bands. I need to…
noste99
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Best C++ STL container to store bodies in an N-body simulation?

I am writing an N-body simulation in C++ that has to be able to deal with large N ($N \le 10^6$). Everything has been going well so far, but now that I have started to code in collisions between bodies (which can result in mergers - which means that…
Gregor Hartl Watters
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