There are two reasons for the friction force: unevenness of surfaces and adhesion. The adhesion comes due to interaction between neutral molecules aka the Van Der Waals force. Because of adhesion the friction force can exceed object’s weight, which … Continue reading
They say systems are quasi-independent when they either interact strong for a short time or do that weakly, e.g. through their surfaces. The Gibbs’s distribution (1901) defines the probability to find such a weakly interacting subsystem of a big … Continue reading
Prior the recombination into atoms, the now visible matter of the universe consisted of electron-nucleus plasma. The nuclei in there were basically hydrogen (three fourth) and helium (one fourth). Their abundances were defined by the available number of protons … Continue reading
There are four parameters that govern the universe expansion. First, the energy density of relativistic particles mostly is that of Cosmic Microwave Background photons. This quickly falls as the space scale-factor grows so contributes to the expansion very little. … Continue reading
Supernova explosions are rather rare events so the last one seen by the naked eye in our galaxy was described by Johannes Kepler in 1604. For several months, that was the brightest star in the sky so one can … Continue reading
The simplest and the oldest way to measure distances to stars is the parallax method. This utilizes variation of the angle between a star and a benchmark direction as an observer changes its position in space, basically moving with … Continue reading
The zero-zero component of the Einstein’s equations for gravity with the metric of the expending universe is called the Friedman equation. We use this differential equation to calculate the behavior of the expending space. The equation includes two unknown functions … Continue reading
Nuclear fusion power should be much chipper an safer than that from uranium-plutonium fission. The fuel for the fission not only needs expensive mining but also enrichment by a fissile uranium isotope. Conversely, the fusion fuel, deuterium is readily … Continue reading
The speed of sound waves as well as the speed of light is not changed by the motion of a source of waves. For example, when a sound source moves towards a listener, each next vibration reaches the listener’s … Continue reading
The electric field strength of light waves coming from the Sun is of course oriented randomly. There were found some transparent compounds which allow a light wave to pass through only having definite direction of the wave field strength. … Continue reading
The first thing which the Newton second law failed to foretell were distances between electron possible orbitals in an atom. The electron’s energy spectrum appeared to be discontinuous so a novel equation had to give a set of discrete solutions. … Continue reading
Look, to know the exact value of some physical quantity you have to measure it using some instruments — devices made of artificial and natural materials. In the process of measurement, the material of instruments interacts with with the … Continue reading
Indeed, we can see stars and planets while particles of cosmic dust are only detectable since they change spectra of stars’ radiation reddening them. As light passes through interstellar cosmic dust, its particles absorb blue photons more than the … Continue reading
First of all, it was recently discovered that despite the temperature and matter density being cosmically low, chemical reactions at the surface of a dust particle can create organics that could be a cradle of life. Being glued up … Continue reading
Thanks Faraday we learned the change of magnetic flux through a conductor results in a circular current appearing in this conductor. The Lenz’s law defines such a direction of this current that magnetic field induced by the current compensates … Continue reading
Indeed, electrons undergo diffraction at a crystalline target. Therefore an electron beam hits a suitable crystal lattice, one can see on a screen an interference pattern typical for waves. The beam here is comprised of a lot of electrons … Continue reading
Electrons are tiny, so a nickel surface should reflect them at various angles since a sample of nickel consists of many randomly oriented small crystals. This is called the diffuse reflection. This is what Davisson and Germer thought in … Continue reading
What is light had always been mysterious for thinking people. Newton believed there are particles carrying light, explaining thereby why an obstacle in the light way creates a shadow on a screen. A century later, they discovered light is … Continue reading
It appears that periodical phenomena, e.g. waves are of utmost importance in nature. In practice, waves of different frequencies are superimposed so that the resulting periodical phenomenon is not of sinusoidal shape. Then, how can we deal with them … Continue reading
Perception by ear (listening) is easy for someone while for others it is difficult to understand what is said in a foreign language, even though all the words are known to the listener. He/she just does not recognize them. … Continue reading
You know, electromagnetic waves bring information from the early Universe as well as provide the information exchange between our smartphones. In physics, to mathematically describe waves, we use so called complex exponential function. Its exponent includes an imaginary unit. … Continue reading
Precision here implies repetition of measurements to minimize deviation of the average result of the measurements from the expected value of a physical quantity. Such deviation is normally caused by random (stochastic) errors. Nonetheless, this average value may still … Continue reading
By the end of the 19th century, it became clear from the development of chemistry that substances are composed of atoms. Guesses about their existence arose earlier, in ancient Greek science, from the desire to give nature a coherent … Continue reading
Einstein noted the unthinkable tenacity with which Kepler sought harmony in the motion of planets, while around Kepler, on Earth, there was not even a suggestion of harmony. To begin with, he was born prematurely, then contracted smallpox yet … Continue reading
Behind the Iron Curtain, Soviet physicists worked actively and nevertheless made a number of fundamental discoveries. At first, however, they were not isolated from the world — they learned from and worked with European scientists. One of the founding … Continue reading
Nowadays, we are transmitting colossal streams of data, including cellular and Wi-Fi, using ultra-high frequency electromagnetic waves. This had began in 1820, with the discovery of Oersted and Ampere that the movement of a charge in a conductor creates … Continue reading
In the III century BC, Aristarchus of Samos had concluded that the Earth and other planets orbit around the Sun. He also guessed about the rotation of the Earth around its own axis. However, it took a millennium and … Continue reading
It started with the fact that the ancient Greek scientist Hipparchus compiled a star catalog in the century II BC. He subdivided the stars into classes according to their brightness. Then, after three centuries, Ptolemy in his scientific treatise … Continue reading
About irreversible processes… The everyday experience seems to tell us that time differs from the spatial dimensions on having a direction from the past to the future. Therefore, in the first half of the XX century, Arthur Edington has introduced … Continue reading
On the mind demons… To put things in order, as is well known, you need to do some work. In thermodynamics, this (second) law is expressed in the fact that the disorder of molecule motion in a container with gas, … Continue reading
About the aggressiveness of video Video games clearly show the current level of computer technology — their software is able to eat the most modern video hardware. Therefore, those who find pleasure in the illusory world of computer games need … Continue reading
On peculiarities of discussion Despite the fact that the fundamental physics is an exact science, under the guise of scientists a kind of demagogues can be found there. All that they are interested in science, it’s a personal benefit. In … Continue reading
Trying to do without the perception through feelings The searches for a hypothetical tachyon particle were active at the end of the last century. It was expected that when moving through a detector, a charged tachyon would leave no trace … Continue reading
Desperately encountering the light barrier Rebellious idea of particles faster than light has naturally arose with the knowledge of the special role of the speed of light as a limit up to which anything massive could be accelerated in our … Continue reading
On a pleasant discovery The discovery of the fourth kind of quarks named charmed (or c) quark in 1974 has suggested this isn’t all and reinforced the belief that there should be at least two another kinds of heavy quarks … Continue reading
As elsewhere, there are very different characters among scientists. Some get from physics just exercises for their intelligence, which gives them the fullness of life, as a sport for a body. They feel like they are involved in the … Continue reading
On trust to the own imagination Without the knowledge accumulated in centuries, one fails even to make a step in physics. On the other hand, without the imagination, how can you perceive new things that are absolutely unknown yet. Therefore, … Continue reading
About the adventures of a hadron in matter Initially the hadron will fly in the substance without incident, just ripping electrons from orbits on its way if this is a charged hadron, such as a proton or pion. But when … Continue reading
About the commitment to discover the neutrinoless conversion Following the discovery of neutrino oscillations, experiments on the search for neutrinoless muon-to-electron conversion have started in the United States and Japan. Such a conversion would violate the customary law of conservation … Continue reading
On the difficulties a lonely lepton In conversions of elementary particles into each other, the total electric charge of the particles before conversion is equal to that after. If electrons, muons, tau-leptons or neutrinos are involved in the conversion, similarly … Continue reading
About sophisticated stuffing of elementary particle with a hadron charge inside Well, at first they thought protons and neutrons that make up nuclei of atoms of matter are indivisible particles. That’s why they call them fundamental, but when in 1968 … Continue reading
On simulation of status of a star In order to build an expensive detector for experiments at accelerators or in space, one should carefully calculate the response it gives to elementary particles trapped in it. Here, the nature has prepared … Continue reading