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Questions tagged [randomness]

Randomness covers questions having to do with the concept of randomness in physical processes and questions about determinism vs indeterminism or interpretations thereof. Question related to concepts of probability may also use this tag.

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Quantum: Which improbable macroscopic events are possible?

Basically, the title. Web search had not found pages in top results with similar QA. E.g. I understand nuclear blast can just end at any time because random chain-reaction has probability of not ...
Martian2020's user avatar
3 votes
1 answer
47 views

Asymptotic form of solution to biased random walk

(Cross post from math.stackexchange) Consider a continuous time biased random walk on a 1D lattice. The random walker walks with rate $k_\mathrm{R}$ to the right and with rate $k_\mathrm{L}$ to the ...
Caesar.tcl's user avatar
2 votes
1 answer
50 views

Anderson localization in the continuum case

I haven't looked into Anderson localization before. A quick review of the available information gives the impression that this phenomenon has mainly been studied for the case of a discrete random ...
Gec's user avatar
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3 votes
1 answer
409 views

Is the collision in LHC quantum mechanically so we cannot predict the trajectory?

I'm puzzled as always. In the LHC 2 streams of particles are accelerated in opposite direction and allowed to smash against each other in a controlled accident, then is it classical or quantum ...
user6760's user avatar
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2 votes
1 answer
122 views

Why aren't completely random quantum states 'physical'?

I've come across the statement that 'completely random states are generically not 'physical', in the sense that they cannot be eigenstates of Hamiltonians with local interactions (in 1D)'. Reference: ...
Tanmay Bhore 's user avatar
3 votes
0 answers
38 views

Various types of correlation functions in models with random interactions

In the Ising model, spin correlations are characterized by the following correlation function $$ C_{ij} = \langle \sigma_i\sigma_j\rangle - \langle \sigma_i\rangle\langle \sigma_j\rangle $$ where $\...
Gec's user avatar
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0 votes
3 answers
122 views

What is really meant by randomness in quantum physics [closed]

I don't really know if my question even makes sense but, we know that for the double slit experiment, there is no way possible of telling which slit the electron will pass, prior to observing. Does ...
user279163's user avatar
0 votes
0 answers
41 views

Stochastic thermodynamical entropy production on growing state space

Suppose we have a stochastic process for a biased random walker starting at a position $x_0 = 0$. At a discrete time $n$, it can either move a distance $s^n$ to the right with probability $p$ or a ...
JonasB's user avatar
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0 votes
1 answer
35 views

How do I compute the bounds of random walk for a given ellapsed time?

I am trying to model random walk of a gyro, given some manufacturer specifications of maximum random walk in units of degrees per root-hour. My first step was to generate white noise with a standard ...
rocksNwaves's user avatar
0 votes
0 answers
28 views

Which textbooks for random (Brownian) motion derivations? [duplicate]

I am a chemist currently trying to dive in to details of random motions. I have been studying Einstein-Smoluchowski treatment, and want to learn further (Fokker-Plank's equation and Langevin treatment ...
0 votes
1 answer
113 views

Error analysis for counting experiments

i am trying to refresh my knowledge in error analysis and stumbled over an interesting question. Suppose i have a radioactive compound and i want to measure the standard deviation of the decay count. ...
vreithinger's user avatar
-4 votes
2 answers
156 views

Is randomness in quantum physics adequately formulated?

According to most experts' interpretations of quantum physics, some quantum event outcomes are random; they are not part of any cause-and-effect chain. I'm struggling to find a thorough definition of ...
Johan Rönnblom's user avatar
1 vote
1 answer
306 views

Is Quantum randomness true randomness? [closed]

I would like you guys to read it, and see whether it makes sense, and correct me if anything is wrong. I'm not an expert on these topics, so I understand if very wrong. It would be wonderful if you ...
Nathan's user avatar
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0 votes
0 answers
59 views

Is the universe deterministic, random, or both? [duplicate]

It occurred to me that the limits of possibility to the nature of the universe is it is either deterministic ie we are all at the will of natural laws that determine the outcome of events from the ...
8Mad0Manc8's user avatar
1 vote
1 answer
57 views

Is the random current model tight (in the sense of probability)?

Let us consider the random current model (of the classical Ising model) on $\mathbb{Z}^d$. More specifically, we have probability measures $\mathbb{P}_L$ on the product space $\mathbb{N}^{E_L}$ where $...
Andrew Yuan's user avatar
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23 votes
7 answers
3k views

Does the bias in a loaded die depend on gravity?

Suppose I bias a cubic plastic die by incorporating a lead pellet hidden just behind the '1' face, so that the probability $P_6$ of rolling a 6 is greater than the symmetric 1/6. Its exact behaviour ...
RogerJBarlow's user avatar
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4 votes
3 answers
581 views

Scientific determinism and the Heisenberg's uncertainty principle

I'm reading Brief Answers to the Big Questions by Stephen Hawking. In chapter 4, it discusses whether we can predict the future. As many have known that Laplace put forth that if we knew the positions ...
Khanh's user avatar
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13 votes
3 answers
4k views

Is Brownian motion truly random?

We say that Brownian motion is caused by the random collisions of particles. But let's consider an ionized gas; in that case, there's a nonzero net charge on the atom. Doesn't this mean the ...
Razz's user avatar
  • 441
8 votes
2 answers
3k views

How accuratley can you determine the number of matchsticks in a matchbox from the sound it makes when you shake it?

This question is part of the International Physics Tournament 2023. The entire problem statement reads : How accurately can you determine the number of matchsticks in a matchbox from the sound it ...
Sriram S's user avatar
  • 101
1 vote
1 answer
161 views

True Randomness/unpredictability in infinite quantum coin toss sequences?

In Comments on indeterminism and undecidability the abstract reads: "In a recent paper 1, it has been claimed that the outcomes of a quantum coin toss which is idealized as an infinite binary ...
Willpergg's user avatar
-1 votes
1 answer
295 views

Do random events really exist? [closed]

To highly clarify my question, let me define what I mean by a random event: "the event e is random, if and only if by having all the data about an event e, we cannot predict the consequences of ...
sbh's user avatar
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0 votes
1 answer
103 views

Geiger tube counts-per-minute Poissonian, but counts-per-hour not. Why?

I am testing a Geiger tube and counting its pulses. Because the pulses are random, I expect the counts-per-minute (cpm) to follow a Poisson distribution. That's indeed what I found: mean cpm = 38.39 ...
Nick Lee's user avatar
  • 103
2 votes
1 answer
68 views

The Physical Meaning of Variance of Random Matrix Entries

I am trying to make some physical sense of the Hamiltonian described on pages 1, 2 here. The part I don't get is in the image attached below. I understand what the variance of each entry term tells me ...
Sal_99's user avatar
  • 423
9 votes
5 answers
1k views

Sufficient and necessary conditions on random walk to obtain standard diffusion equation

In the simplest random walk model that is generally considered, the probability of the finding the particle at time $t$ in $x$, $P(x,t)$ is given by, $$ P(x,t) = \frac{1}{2}\big[ P(x-a, t-\tau) + P(x+...
user35952's user avatar
  • 2,995
0 votes
1 answer
216 views

Is the cosmic background radiation random and Kolmogorov complexity

In the article https://arxiv.org/pdf/physics/0510102.pdf the idea arises that if there was a Creator of the Universe and wanted to send us a message, then the "right" place to do it, would ...
mathoverflowUser's user avatar
0 votes
2 answers
229 views

Per Newtonian mechanics, a coin toss exhibits deterministic chaos theory, but could relativity cause a probabilistic outcome of a coin toss?

It took me a long time to accept that a coin toss boils down to deterministic chaos theory. For example, the typical near 50/50 odds for outcomes of heads or tails results from complex initial ...
James Goetz's user avatar
-3 votes
2 answers
138 views

How can randomness occur in the case of radioactive decay ? Isn't there supposed to be a rule for everything that's driven by a non conscious mind? [duplicate]

I'm not trying to be unscientific here but i cannot wrap this around my head that scientifically anything can work randomly except a conscious mind which is capable of making a random decision. how ...
Vineetz's user avatar
11 votes
7 answers
4k views

Does a random number generator have real entropy?

In thermodynamics, entropy is defined for gases. Of course, my laptop is not a gas. However, it contains a random number generator and I have seen the word ‘entropy’ being used in this context. Is ...
Riemann's user avatar
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2 votes
0 answers
87 views

Is there any paper/experiment on the deterministic behavior of coin-tossing?

I do not have background in Physics but Statistics. I am working on a small project on philosophy of probabilistic modeling. Of course, we often model coin-tossing as if it comes from a Bernoulli ...
0 votes
1 answer
158 views

Does the human brain use random number generators? [duplicate]

Neurons fire depending on the impulses they get from other neurons. This seems to be 'deterministic'. However, sometimes it might be useful to use random processes instead. Does the human brain have ...
Riemann's user avatar
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1 vote
1 answer
100 views

Conditional and unconditional interpretations of mean inter-collision times

This question appeared in a study guide for my graduate level written exam in physics. (It may have been the one from the University of Chicago.) I see that a similar question was asked here What is ...
Peter Leopold's user avatar
0 votes
0 answers
115 views

Kramers' Degeneracy and Geometric Symmetries

I am currently reading the third edition of 'Quantum Signatures of Chaos' by Fritz Haake and trying to work through section 2.7 (Titled "Kramers' Degeneracy and Geometric Symmetries"). I am ...
Kristian Stokkereit's user avatar
2 votes
2 answers
125 views

Does quantum decoherence desctibe a deterministic universe?

QM describes a system, whose state evolve unitarily, which is deterministic. The apparent non-determinism comes from the measurement problem, where the state is projected to some subspace in a ...
Rd Basha's user avatar
  • 2,141
4 votes
2 answers
87 views

Is the randomness generated by quantum phenomena measurably better than the randomness generated by the best computational algorithms?

I am aware that quantum phenomena can be used to generate random sequences of numbers. Are such sequences measurably better than the random sequences generated by the best computational algorithms? ...
MarkVonTexas's user avatar
2 votes
1 answer
108 views

Questions about the intuition on or physical meaning of probability space, random number, and stochastic process

I have a question about the physical meaning of, or the mathematical intuition on, the mathematical concept of probability space, random number, and stochastic process. Mainly, I would like to ask ...
Neophyte's user avatar
  • 340
-1 votes
2 answers
68 views

Information content needed to predict a physical coin flip perfectly [closed]

Let's just take a typical coin flip where a person flips the coin off their finger into the air (some reasonable distance, say 30-40 cm or so), catches it, and opens their hand to reveal one side face ...
jdods's user avatar
  • 181
0 votes
0 answers
45 views

How to calculate variance of adjacency matrix $A$?

I'm studying random matrix theory. How to calculate variance, $<A_{ij}^2>$ for every $i ≠ j$, if $A$ is a real symmetric $N × N$ uncorrelated random matrix? and I can't understand why the <A_{...
0018's user avatar
  • 101
2 votes
0 answers
100 views

Random matrix theory and the singularities of the Weingarten function

In the random matrix theory literature, one often encounters identities associated with averages over ensembles of random unitaries. For a simple example let's say we're interested exclusively in $2\...
miggle's user avatar
  • 759
3 votes
1 answer
157 views

Cosmology context - MCMC code : Recomputation of covariance matrix after each point accepted

I am working on a MCMC code (basically with Metropolis-Hastings) and I would like to understand different important points. We always mention the covariance matrix which is used in the computation of ...
user avatar
0 votes
5 answers
1k views

Is there consensus among physicists that reality is fundamentally deterministic? [duplicate]

Does Heisenberg’s Uncertainty Principle mean that the universe cannot deterministically be predicted by observers, or does it mean that the universe is inherently indeterministic, meaning that the ...
Peter Jordanson's user avatar
2 votes
0 answers
81 views

What is the probability that a random walk forms (almost) a circle?

Given is a random walk of a particle in 3d (such as an atom in a liquid). The particle proceeds randomly (in 3d), with an average straight displacement length a. Is there a way to get a probability ...
user avatar
3 votes
3 answers
240 views

Why can’t quantum randomness be understood as epistemic? [duplicate]

I often hear people say that quantum randomness is “true randomness”, but I don’t really understand it. Please bear with my question. Before the development of quantum physics, randomness is ...
J Li's user avatar
  • 131
3 votes
6 answers
2k views

Is radioactive decay deterministic? [duplicate]

Suppose you know at time $t$ that there is some atomic nucleus that radioactively decays. If you were to magically roll back the universe to the exact same state and let it continue as per usual ...
Water's user avatar
  • 185
0 votes
0 answers
53 views

Is there any concept in physics, that could potentially in the future get rid of "randomness"? [duplicate]

This question was very interesting to a non physicists like me question (I am computer scientist and I work with "pure random" crypto hardware that uses quantum phenomena) Obviously string ...
Sfp's user avatar
  • 101
2 votes
0 answers
42 views

Is a coin toss pseudo-random or truly random? [duplicate]

I wonder if a coin toss is pseudo-random or truly random. Sure, you could say that a coin toss is pseudo-random because you don't know the speed of the coin or its rotation, but if you were to include ...
Luqus's user avatar
  • 21
0 votes
1 answer
88 views

How many flips does a tossed macroscopic coin need to go through until the coinflip's result becomes indeterministic?

A coinflip is a macroscopic event and is deterministic in nature. A coin-flipping machine that operates at the greatest physical precision possible would be able to predict the coinflip's result (...
Jurhas's user avatar
  • 1
4 votes
2 answers
228 views

Source of randomness

Is the random nature of all macroscopic phenomena like for example, turbulence or chemical kinetics ultimately traceable to quantum randomness?
Ajit Haridas's user avatar
1 vote
0 answers
383 views

Annealed and quenched free energies

For the systems with random fields and interactions, annealed and quenched free energies are defined: $$ F_a = -\theta\log\left(\overline{Z}\right),\quad F_q = -\theta\ \overline{\log(Z)}. $$ Here, ...
Gec's user avatar
  • 5,697
1 vote
0 answers
22 views

How are single photons correlated inside the "coherence time" of the laser? (And how would this affect a random number generator?)

This review on quantum random number generation describes how random numbers can be generated from a simple optical setup. In one example setup they give: weak light travels through a beam splitter ...
Steven Sagona's user avatar
2 votes
0 answers
236 views

Are phase transitions in one-dimensional random-field Ising model possible?

Translationally invariant one-dimensional models, with interactions of finite range and a finite number of states at the site, don't allow phase transitions at positive temperatures. This fact is a ...
Gec's user avatar
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