Last time we have written on the power spectral density and we have “analyzed” deterministic periodic time series. This time we will consider spectral densities of some stochastic processes. Continue reading “Power spectral density (part 2)” »
Keyword: statistical physics
Power spectral density (part 1)
Here, on the Physics of Risk, we frequently talk about two essential statistical features of the time series – probability and spectral densities. The probability density function should well known to our readers – it is related to the distribution of time series values. On the Physics of Risk we have also a Lithuanian-only article on this topic (see it here). So the time has come to discuss the power spectral density. Continue reading “Power spectral density (part 1)” »
FuturICT: participatory science and computing for our complex world
The most active and well known scientists contributing towards FuturICT project have organized their ideas into few articles, which discuss the current situation in contemporary complex social system modeling. These articles we published in a special issue of “The European Physical Journal Special Topics”. Most of the articles are available for free, thus we invite you to familiarize yourselves with them.
Vygintas Gontis: Econophysics – brand new outlook into social sciences
Econophysics is not a very well known interdisciplinary field of research in Lithuania. There are very few Lithuania based scientists who are related to this very young and rapidly developing branch of Physics. Therefore we, being ones of the few, feel an obligation to introduce Econophysics to the other scientists, businessmen and the whole broader society. In this text we will discuss the basic ideas, current trends and the most common problems relevant to the field of Econophysics.
The name of Econophysics implies the application of physics, mostly the methods taken from Statistical Physics, to the Economics. Though until recently most of the econophysicists used to focus on the financial markets. Currently the field is expanding very rapidly and now concerns something more than just regular Economics or Finance – many physicists now attempt to tackle problems in the other social sciences. For these broader approaches there are other overlapping terms including Sociophysics, Physics of Risk, Physics of Socio-Economic Systems and other.
At this point we would like to stop the discussion on the use of the terminology. Recall that the aim of this text is somewhat different from that. We aim to familiarize you with the Econophysics! Continue reading “Vygintas Gontis: Econophysics – brand new outlook into social sciences” »
Seminar at VU MIF: Agent-based Versus Macroscopic Modeling of Competition and Business Processes in Economics and Finance
Topic: “Agent-based Versus Macroscopic Modeling of Competition and Business Processes in Economics and Finance”
Speaker: dr. Vygintas Gontis
Briefly: The talk will be focused on the agent-based and stochastic modelling done by the Department of the Theory of Processes and Structures of the VU ITPA.
When? 6th of November, 17:00.
Where? VU Faculty of Mathematics and Informatics (Naugarduko g. 24, Vilnius), 400 auditorium.
Organized by: Department of the Mathematical Analysis of the VU MIF.
Quantum mechanics + statistical physics = ?
Quantum mechanics and statistical physics use very similar and inter-connected concepts. Ex. the latter is concerned with distribution and probabilities, while the former operates with wave functions and amplitudes. Even the essential equations, master and Shrodinger, appear to be similar:
The only difference is the imaginary factor i! But these similarities lie just on the surface… Continue reading “Quantum mechanics + statistical physics = ?” »
Seminar at VU Faculty of Physics: Brief introduction into the Physics of Risk
Topic: “Physics is not a risk: Brief introduction into the Physics of Risk”
Speaker: Aleksejus Kononovičius
Briefly: Social sciences have accomplished many different things. Yet it should be evident that there is a place for improvements – to look into the old and new social problems a bit differently. As many of the social problems are strongly non-linear and very complex, the physicists’ point of view is very useful. This, new, point of view is known as Physics of Risk.
When? 18th of October, 17:00.
Where? VU Faculty of Physics (Saulėtekio al. 9, III rūmai, Vilnius), 201 auditorium.
Organized by: VU Faculty of Physics Students Scientific Association.
Facebook event: here.
Slides: download (in Lithuanian).
Obtaining surface area using Monte Carlo method
Imagine that you have to measure the surface area of the lake by using only a cannon! Let us assume that the geometric shape of the lake is too complex to be dealt with using simple formulas and that you have almost infinite supply of cannon balls. In such case you just have to hope that you are perfectly random shooter! Why so?
If your shots cover the hitting area of the cannon uniformly then you can obtain the area of the lake by estimating the probability to hit it:
here 
is an estimate of the surface area of certain geometric shape (lake for example), 
is an estimate of the probability to hit the shape, while 
is the hitting area of the cannon. The obtained are of course will be only approximate, but one can arrive reasonably near the actual answer.
Next we illustrate this method by applying it towards three geometric shapes – square, circle and Euclidean egg. Why the Euclidean egg? Well, there are numerous reasons for it, one of them being Easter. Happy Easter! Continue reading “Obtaining surface area using Monte Carlo method” »
Presentations at 39th Lithuanian national physics conference
We have contributed two presentations towards the recent 39th Lithuanian National Physics Conference, which was organized by Vilnius University and Lithuanian Physicist Society. Oral presentation by A. Kononovicius was based on some of the models presented on Physics of Risk website, while poster presentation by R. Kazakevičius tackles very general problem related to the Physics of Risk. Continue reading “Presentations at 39th Lithuanian national physics conference” »
Ising model
Ising model is a generalized mathematical model of feromagnetism in statistical physics. In this model particles having magnetic spin are put inside vertices of graph. In general case structure of graph can vary alot, but in the ussuall case selection is limited to the lattices of different dimensions. Behavior of such system is observed at different temperature in the quest to find critical temperature at which phase shift occurs. If you want to familarize yourself more with Ising model and it’s various interpretations, you should read 1, 2 works, because in this text we will only consider one possible, numerical, algorithm – heat bath algorithm.
Continue reading “Ising model” »
