科普物理
Interstellar probes can carry out slingshot manoeuvres around the stars they visit, gaining a boost in velocity by extracting energy from the star's motion around the Galactic Centre. These maneouvres carry little to no extra energy cost,…
The kinematics of the Solar zenith passage on the Earth was shown as a simple harmonic motion. This analytical model used the uniform circular motion to describe the Earth's rotation relative to its axis and relative to the Sun, also this…
An introduction is given to discussions on the possiblity of fabricating spacetime geometries allowing time-travel scenarios with the help of matter possessing typically quantum features. Those scenarios are considered in the framework of…
Paran\'a Ra'anga (the image of Paran\'a, in Guaran\'i) is the name of a cultural and scientific expedition that traveled the rivers: R\'io de la Plata, Paran\'a and Paraguay, from Buenos Aires to Asunci\'on, during March 2010. The project…
Experiments in mechanics can often be timed by the sounds they produce. In such cases, digital audio recordings provide a simple way of measuring time intervals with an accuracy comparable to that of photogate timers. We illustrate this…
Google Earth photographs often show ships and their wakes in great detail. We discuss how the images can be used to calculate the velocity of these ships.
In this paper we put forward a proposal to use Near Earth Objects as radiation shield for deep space exploration. In principle these objects can provide also a spacious habitat for the astronauts and their supplies on their journeys. We…
The electrostatic field energy due to two fixed pointlike charges shows some peculiar features concerning the distribution in space of the field energy density of the system. Here we discuss the evaluation of the field energy and the…
The problem of a cylinder of mass m and radius r, with its center of mass out of the cylinder axis, rolling on an incline that makes an angle with respect to the horizontal is analyzed. The equation of motion is partially solved to obtain…
Following previous works on ancient myths in Greek and Latin literature regarding Ursa Major, and the possible relation with the ancient shape of the constellation, we discuss further this case in the light of the evolution of Homo sapiens…
Conventional Newtons rings is generally used in undergraduate laboratory to determine the average wavelength of Na doublet. A minor modification of this setup enables us to view simultaneously Newtons rings both in reflected as well as…
We introduce the historical development and physical idea behind topological Yang-Mills theory and explain how a physical framework describing subatomic physics can be used as a tool to study differential geometry. Further, we emphasize…
In this report are recalled in a simple form some of the main concepts about neutrinos, starting from their discovery and classifying them in the Standard Model of the Microcosm. Then are presented the main natural sources of neutrinos,…
Data is presented that confirms that hydrophobic coatings reduce friction between objects and water. The results show that the average time it took for the ball with the hydrophobic coating traveled at an average of about 6 inches per…
Mirror adapters can match a camera and a projector to the task of producing and visualizing a stereo pair. The imaging digital technology can benefit on the traditional optical technology of the last century to get more compact and…
We suggest that the recently observed superluminal neutrino propagation observed by OPERA may have an environmental origin that can simultaneously explain the DAMA/LIBRA annual modulation. Our proposal can be unambiguously tested by the…
We express the position of the Sun in the sky as a function of time and the observer's geographic coordinates. Our method is based on applying rotation matrices to vectors describing points on the celestial sphere. We also derive direct…
Intelligent life can only appear in Universes, whose physical laws support sufficient complexity to make evolution of intelligent beings possible. Even inside those Universes, intelligent life does not appear randomly, but in parts with…
A pareidolic conjecture for the Fermi Large Area Telescope.
One of the greatest difficulties that space exploration faces is the lack of technology necessary to establish large volumes of habitable spaces on site. Both transporting the pre-built enclosures or transporting the equipment necessary for…