科普物理
It is a common practice to fix a vertical gnomon and study the moving shadow cast by it. This shows our local solar time and gives us a hint regarding the season in which we perform the observation. The moving shadow can also tell us our…
A discussion at a Scientific American level of the idea that the constituents of the dark mater in galactic halos are primordial intermediate-mass black holes with masses between ten and one hundred thousand times the solar mass.
Rocking rigid bodies appear in several shapes in everyday life: As furniture like rocking chairs and rocking cradles or as toys like rocking horses or tilting dolls. The familiar rocking motion of these objects, a non-linear combination of…
Due to concerns about environmental and industrial hazards of lead, a number of military, law enforcement, and wildlife management agencies are giving careful consideration to lead-free ammunition. The goal of lead-free bullets is to gain…
We discuss the physics and modeling of latex-rubber slingshots. The goal is to get accurate speed predictions inspite of the significant real world difficulties of force drift, force hysteresis, rubber ageing, and the very non- linear,…
Since its discovery in 1930, Pluto's mass has been a value that has repeatedly been calculated. Additionally, the search for Planet X prior to Pluto's discovery results in mass calculations that date back several decades earlier. Over its…
We present a functional model of neuronal network connectivity in which the single architectural element is the object commonly known in handicraft circles as a pipe cleaner. We argue that the dual nature of a neuronal circuit - that it be…
Seasonality is one of the oldest and most elucidation-resistant issues in suicide epidemiological research. Despite winter depression (also known as Seasonal Affective Disorder, SAD) is known and treated since many years, worldwide…
The last two decades have seen the number of known exoplanets increase from a small handful to nearly 2000 known exoplanets, thousands more planet candidates, and several upcoming missions that are expected to further increase the…
While the concept of the block universe has a most respectable scientific provenance, many physicists nevertheless do not accept that future events are just as embedded in spacetime as are those of the present and the past. This paper…
Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar System. However our planet cannot be considered a fair sample, especially if intelligent life exists elsewhere. Just as a…
We report a non-detection, to a limiting magnitude of V = 18.4 (9), of the elusive entity commonly described as the Tooth Fairy. We review various physical models and conclude that follow-up observations must precede an interpretation of…
Assuming the possibility of existence of a supercivilization we extend the idea of Freeman Dyson considering pulsars instead of stars. It is shown that instead of a spherical shell the supercivilization must use ring-like constructions. We…
In science, as in life, `surprises' can be adequately appreciated only in the presence of a null model, what we expect a priori. In physics, theories sometimes express the values of dimensionless physical constants as combinations of…
In 2013 the Nobel Prize in Physics was awarded to Francois Englert and Peter Higgs for their development in 1964 of the mass generation mechanism (the Higgs mechanism) in local gauge theories. This mechanism requires the existence of a…
The tremendous popular success of Chaos Theory shares some common points with the not less fortunate Relativity: they both rely on a misunderstanding. Indeed, ironically , the scientific meaning of these terms for mathematicians and…
In this paper it is performed the biomechanical analysis of Uchi Mata family, the unifying vision of biomechanics let coaches and teachers to approach competition and lessons in different way. Uchi Mata and all throws that are in the…
This article is the detailed version of a paper on dark matter, dark energy, and modified gravity, published in the December 2015-January 2016 special issue of "La Recherche" (in French)
The most abundant particles in the Universe are photons and neutrinos. Both types of particles are whirling around everywhere, since the early Universe. Hence the neutrinos are all around us, and permanently pass through our planet and our…
Ancient objects made of noble metal alloys, that is, gold with copper and/or silver, can show the phenomenon of surface enrichment. This phenomenon is regarding the composition of the surface, which has a percentage of gold higher than that…