Showing posts with label theoretical physics. Show all posts
Showing posts with label theoretical physics. Show all posts

Tuesday, 3 June 2025

Compressive algorithmic randomness:
Gibbs-randomness proposition for massively energy efficient deep learning

Figure: Dual Tomographic Compression
Performance, Süzen, 2025.
Preamble

Randomness is elusive and its probably one of the outstanding concepts for human scientific endeavour, along with gravity. Kolmogorov complexity, appears to be so novel in trying to answering "what is randomness?". The idea that the length of the smallest model that can generate the random sequence determines its complexity was a turning point in history of science. Similarly, it implies choosing the simplest model for explaining a phenomenon. That's why Kolmogorov's work was also supported by the ideas of Solomonoff and Chaitin. A recent work, explores this algorithmic information from compression perspective with Gibbs entropy.

A strange tale of path from applied research to fundamental proposition. 

During study of model compression algorithm development, I have noticed an amazing behaviour that information, entropy and compression over compression process have a more in depth. 

New concepts in compression and randomness via train-compress cycles

Here, we explain the new concepts for both deep learning model compression and on the interplay between compression and algorithmic randomness.

Inverse compressed sensing (iCS): Normally CS procedure is applied to reconstruct an unknown signal with fewer measurements. In the case of deep learning train-compress, weights are known at one point in the training cycle. If we create hypothetical measurements, using CS formulations, we can reconstruct weights sparse projection. 

Dual Tomographic Compression: Applying iCS for the input and output of neuronal level, layer-wise, simultaneously.  

Weight rays:  An output reconstructed vector out of DTC; weights given sparsity level, though they are not generated in isolation but within train-compress cycle.

Gibbs randomness proposition : An extension of Kolmogorov complexity for a compression process. That, directed randomness is the same as complexity reduction, i.e., compression. 

Conclusion 

A new technique called DTC can be used to train deep learning with model compression on the fly. This gives rise to massively energy efficient deep learning, reaching almost ~98% reduction in energy use.  Moreover, the technique also demonstrated an extended version of Kolmogorov complexity. 

Further reading 

Paper & codes are released :


Cite as 

 @misc{suzen25car, 
     title = {Compressive algorithmic randomness: <br>Gibbs-randomness proposition for massively energy efficient deep learning}, 
     howpublished = {\url{ https://science-memo.blogspot.com/2025/06/compressive-algorithmic-randomness.html}}, 
     author = {Mehmet Süzen},
     year = {2025}
}  

Saturday, 25 February 2023

Loschimidt's Paradox and Causality:
Can we establish Pearlian expression for Boltzmann's H-theorem?

Boltzmann (Wikipedia)
  • Post covers the papers: H-theorem do-conjecture, M. Süzen,  arxiv:2310.01458 (2023) 

Preamble

Probably the most important achievement for humans is the ability to produce scientific discoveries, that  helps us objectively understand how nature works and build artificial tools where no other species can.  Entropy is an elusive concept and one of the crown achievements of human race. We question here if causal inference and Loschmidt's paradox can be reconciled. 


Mimicking analogies are not physical

Before even try to understand what is a physical entropy, we should make sure that there is only one kind of physical entropy from thermodynamics, formulated by Gibbs-Boltzmann ($S_{G}$ and $S_{B}$).  Other entropies such as Shannon's information entropy are all analogies to physics, and mimicking concepts.

Why counting microstates are associated with time?

The following definition of entropy is due to Boltzmann but Gibbs' formulation tend to provide equivalence, technically different formulations aside, they are actually equivalent.

Definition 1: An entropy of a macroscopic material is associated with larger number of states its constituted elements take different states, $\Omega$. This is associated with $S_{B}$, Boltzmann's entropy.  

Now, as we know from basic thermodynamics classes that entropy change of a system can not decrease, so the time's arrow. 

Definition 2: Time's arrow is identified with change in entropy of material systems, that $\delta S \ge 0$.

We put aside the distinction between open and close systems and equilibrium and non-equilibrium dynamics, but concentrate on how come counting system's state's are associated with time's arrow? 

Loschimidt's Paradox: Irreversible occupancy on discrete states and causal inference

The core idea probably can be explained via discrete lattice and occupancy on them over chain of dynamics. 

Conjecture 1: Occupancy of $N$ items on $M$ discrete states, $M>N$, evolving with dynamical rules $\mathscr{D}$ necessarily increases $\Omega$, compare to the number of sampling if it were $M=N$. 

This conjecture might explain the entropy increase, but irreversibility of the dynamical rule $\mathscr{D}$ is required addressing Loschimidt's Paradox, i.e., how to generate irreversible evolution given time-reversal dynamics. Actually, do-calculus may provide a language to resolve this, by inducing interventional notation on Boltzmann's H-theorem with Pearlian view. The full definition of H-function is a bit more involved, but here we summarise it in condensed form with a do operator version of it.

Conjecture 2 (H-Theorem do-conjecture): Boltzmann's H-function provides a basis for entropy increase, it is associated with conditional probability of a system $\mathscr{S}$ being in state $X$ on ensemble $\mathscr{E}$. Hence, $P(X|\mathscr{E})$. Then, an irreversible evolution from time-reversal dynamics should use interventional notation, $P(X|do(\mathscr{E}))$. Then information on how time reversal dynamics leads to time's arrow encoded on, how dynamics provides an interventional ensembles, $do(\mathscr{E})$.

Conclusion

We provided some hints on why would counting states lead to time's arrow, an irreversible dynamics.  In the light of the development of mathematical language for causal inference in statistics, the concepts are converging. Along with understanding Loschmidt's Paradox via do-calculus, it can establish an asymmetric notation. Loschmidt's question is long standing problem in physics and philosophy with great practical implications in different physical sciences.

Further reading

Please cite as follows:

 @misc{suezen23lpc, 
     title = {Loschimidt's Paradox and Causality: Can we establish Pearlian expression for Bolztmann's H-theorem?}, 
     howpublished = {\url{https://science-memo.blogspot.com/2023/02/loschimidts-do-calculus.html}}, 
     author = {Mehmet Süzen},
     year = {2023}
}  

@article{suzen23htd,
    title={H-theorem do-conjecture},
    author={Mehmet Süzen},
    preprint={arXiv:2310.01458},
    url = {https://arxiv.org/abs/2310.01458}
    year={2023}
}

Tuesday, 4 October 2022

Heavy-matter-wave and ultra-sensitive interferometry: An opportunity for quantum-gravity becoming an evidence based research

    Solar Eclipse of 1919
(wikipedia)

Preamble
 


   
Cool ideas in theoretical physics are ofter opaque for general reader whether if they are backed up with any experimental evidence in the real world. The success of LIGO (Laser Interferometer Gravitational-wave Observatory) definitely proven the value of interferometry for advancement of cool ideas of theoretical physics supported by real world measurable evidence. An other type of interferometry that could be used in testing multiple-different ideas from theoretical physics is called matter-wave interferometry or atom interferometry: It's been around decades but the new developments and increased sensitivity with measurement on heavy atomic system-waves will pave the technical capabilities to test multiple ideas of theoretical physics. 

Basic mathematical principle of interferometry

Usually interferometry is explained with device and experimental setting details that could be confusing. However,  one could explain the very principle without introducing any experimental setup.  The basic idea of of interferometry is that if a simple wave, such as $\omega(t)=\sin\Theta(t)$, is first split into two waves and reflected over the same distance, one with shifted with a constant phase, in the vacuum without any interactions. A linear combination of the returned waves $\omega_{1}(t)=\sin \Theta(t)$ and  $\omega_{2}(t)=\sin( \Theta(t) + \pi))$, will yield to zero, i.e.,  an interference pattern generated by $\omega_{1}(t)+\omega_{2}(t)=0$. This very basic principle can be used to detect interactions and characteristics of those interactions wave encounter over the time it travels to reflect and come back. Of course, the basic wave used in many interferometry experiments is the laser light and interaction we measure could be gravitational wave that interacts with the laser light i.e., LIGO's set-up.

Detection of matter-waves : What is heavy and ultra-sensitivity?

Each atomic system exhibits some quantum wave properties, i.e., matter waves. It implies a given molecular system have some wave signatures-characteristics which could be extracted in the experimental setting. Instead of laser light, one could use atomic system that is reflected similar to the basic principle. However, the primary difference is that increasing mass requires orders of magnitude more sensitive wave detectors for atomic interferometers. Currently heavy means usually above ~$10^{9}$ Da (comparing to Helium-4 which  is about ~4 Da), these new heavy atomic interferometers might be able to detect gravitational-interactions within quantum-wave level due to precisions achieved ultra-sensitive. This sounds trivial but experimental connection to theories of quantum-gravity, one of the unsolved puzzles in theoretical-physics appears to be a potential break-through. One prominent example in this direction is entropic gravity and wave-function collapse theories.  

Conclusion

Recent developments in heavy matter-wave interferometry could be leveraged for testing quantum-gravity arguments and theoretical suggestions. We try to bring this idea into general attention without resorting in describing experimental details. 

Further Reading & Notes
  • Dalton, mass-unit used in matter-wave interferometry. 
  • Atom Interferometry by Prof. Pritchard YouTube.
  • Newton-Schrödinger equation.
  • A roadmap for universal high-mass matter- wave interferometry  Kilka et. al. AVS Quantum Sci. 4, 020502 (2022). doi
    • Current capabilities as of 2022, atom interferometers can reach up to ~300 kDa.
  • Testing Entropic gravity, arXiv
  • NASA early stage ideas workshops : web-archive

Monday, 2 January 2017

Testing emergent gravity: Gravitational Lensing to atom interferometer

Paranal Telescopes in Chile. (ESO/H.H. Heyer)
In this post, I would like to briefly discuss emergent gravity, an idea, that gravity itself is an artefact of more fundamental description, such as entropy. Despite the fact that we have an experimental evidence of gravitational waves, thus gravity really exist and physically detectable: The recent results of Laser Interferometer Gravitational-Wave Observatory (LIGO) programme in detecting gravitation waves was a landmark experimental evidence supporting Einstein's General Relativity theory.

Emergent Gravity: Verlinde's thesis

Eric Verlinde has proposed a controversial hypothesis in 2010 that gravity is originated from an entropic force [here]. He has shown that both Newtonian and Einstein's gravitational equations are artefacts of entropic force and in 2016 he proposed a similar approach in explaining galactic motions without the need of using dark matter [here].

Testing Emergent Gravity: Gravitational Lensing

Margot M. Brouwer and her co-workers have published a work [here], using weak gravitational lensing data from ESO telescopes. This was the first evidence for Verlinde's theory which attracted a lot of media attention because of implications in our understanding of the nature of gravity.

Testing Entropic Gravity Directly: Atom Interferometer

Despite this initial test of emergent gravity, there is still a lack of direct experimental evidence for Verlinde's initial hypothesis that force laws are artefacts of entropic force. Recently another approach is proposed to test this entropic force argument, [here], using mater-wave interferometry via utilising part of Newton-Schroedinger. The core idea is there is a direct relationship between the gravitational constant G and the atomic system's quantum state. If this is experimentally feasible, maybe with next generation atom interferometer systems, this could be a direct test for Verlinde's entropic force argument.



Tuesday, 13 May 2014

Is ergodicity a reasonable hypothesis? Understanding Boltzmann's ergodic hypothesis

Ergodic vs. non-ergodic
trajectories (Wikipedia)
Many undergraduate Physics students barely study Ergodic Hypothesis in detail. It is usually manifested as ensemble averages being equal to time averages. While the concept of the statistical ensemble maybe accessible to students, when it comes to ergodic theory and theorems,  where higher level mathematical jargon kicks in, it maybe confusing for the novice reader or even practicing Physicists and educator what does ergodicity really mean. For example recent pre-print titled "Is ergodicity a reasonable hypothesis?" defines the ergodicity as follows:
...In the physics literature "ergodicity" is taken to mean that a system, including a macroscopic one, visits all microscopic states in a relatively short time...[link]
Visiting all microscopic states is not a pre-condition for ergodicity from statistical physics stand point. This form of the theory is the manifestation of strong ergodic hypothesis because of the Birkhoff theorem and may not reflect the physical meaning of ergodicity.  However,  the originator of ergodic hypothesis,  Boltzmann, had a different thing in mind in explaining how a system approaches to thermodynamic equilibrium. One of the best explanations are given in the book of J. R. Dorfman, titled An introduction to Chaos and Nonequilibrium Statistical Mechanics [link], in section 1.3, Dorfman explains what Boltzmann had in mind:
...Boltzmann then made the hypothesis that a mechanical system's trajectory in phase-space will spend equal times in regions of equal phase-space measure. If this is true, then any dynamical system will spend most of its time in phase-space region where the values of the interesting macroscopic properties are extremely close to the equilibrium values...[link]
Saying this, Boltzmann did not suggest that a system should visit ALL microscopic states.  His argument only suggests that only states which are close the equilibrium has more likelihood to be visited.

Postscript (June 2022)

The sufficiency of Sparse Visits: Physical states are rarely fine-grained

A requirement for attaining ergodicity is visiting all possible states or regions due to the ergodic theorems of Birkhoff and von Neumann. This requirement is not correct for Physics. The key concepts here are coarse-graining and the sufficiency of sparse visits. Most of the physical systems have equally likely states.


The generated dynamics would rarely need to visit all accessible states or regions. Physical systems are rarely fine-grained and have a degree of sparseness, reducing their astronomically large number of states to a handful. In summary, visiting all physical states or regions in time averages is not strictly needed for the physics definition of ergodicity.


A collection of regions or multiple states with a higher probability will need to be covered to achieve thermodynamic equilibrium. A concept of “sufficiency of sparse visits”. This approach makes physical experiments possible over a finite time consistent with thermodynamics.




Sunday, 22 January 2012

Quantum Mechanics without wavefunction

During my studies I was fortunate enough to write a short review on density functional theory, specifically reduction of computational burden in computing many electron integrals [pdf]. What strikes me in that short literature review a quote that is attributed to van Vleck about the legitimacy of wave function in standard quantum mechanics: ".. wave function has no legitimate scientific concept as pointed out by Van Vleck for many electrons (more than 10 electrons)..." according to Nobel lecture given by Walter Kohn, so the concept of density functionals in solving quantum mechanical problems. In similar lines, recently Israeli-american scientists has formulated the non-relativistic quantum mechanics without the need of wave function or density functions : Quantum states are represented as ensembles of real-valued quantum trajectories, obtained by extremizing an action and satisfying energy conservation [link] I think interpretation of this new results might be quite interesting, worth to think about it.
(c) Copyright 2008-2024 Mehmet Suzen (suzen at acm dot org)

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