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Benvenuti in queste pagine dedicate a scienza, storia ed arte. Amelia Carolina Sparavigna, Torino

Showing posts with label Physics. Show all posts
Showing posts with label Physics. Show all posts

Monday, May 6, 2019

Émilie



Émilie du Châtelet

Poco dopo la scomparsa di Émilie, Voltaire scrisse: 
Je n'ai pas perdu une maîtresse mais la moitié de moi-même.
Un esprit pour lequel le mien semblait avoir été fait. 

Her most recognized achievement is her translation of and commentary on Isaac Newton's book Principia containing basic laws of physics. The translation, published posthumously in 1759, is still considered the standard French translation today. Her commentary includes a profound contribution to Newtonian mechanics—the postulate of an additional conservation law for total energy, of which kinetic energy of motion is one element. This led to her conceptualization of energy as such, and to derive its quantitative relationships to the mass and velocity of an object.

Saturday, March 23, 2019

The Tsallis Distribution

The Tsallis Distribution





The Tsallis distribution was introduced in 1988 by Constantino Tsallis as a generalization of the Boltzmann-Gibbs distribution and has been used in many fields of physics.
The distribution introduces a new parameter q. In the limit where this parameter is 1 it reproduces the standard Boltzmann-Gibbs distribution.

Friday, March 8, 2019

Octonions

The Peculiar Math That Could Underlie the Laws of Nature

"Cohl Furey, a mathematical physicist at the University of Cambridge, is finding links between the Standard Model of particle physics and the octonions, numbers whose multiplication rules are encoded in a triangular diagram called the Fano plane."


Questi ottonioni promettono cose interessanti. 
Gli ottonioni sono un'estensione non associativa dei quaternioni.
L'algebra relativa viene spesso denotata con O.

Adoro le tabelline!

Monday, February 11, 2019

Spins and Dominos

Physicists Found a Brand-New Kind of Magnet Hiding in a Uranium Compound
https://www.livescience.com/64729-new-uranium-singlet-magnet.html

"Under normal circumstances, the magnetic moments in a bar of iron become aligned gradually, without sharp transitions between magnetized and unmagnetized states. In a singlet-based magnet, the jump between states is sharper. Spin excitons, usually temporary objects, become stable when they cluster together. And when those clusters form, they start a cascade. Like dominoes falling into place, spin excitons fill the entire substance very quickly and suddenly, and align with one another.
That's what seems to be happening in USb2."

Monday, December 24, 2018

Dancing light

A team of researchers from Imperial College London, the University of Oxford, and the National Physical Laboratory have experimentally achieved a long-standing goal to demonstrate the so-called "strong-coupling regime" between light and high-frequency acoustic vibrations.

Read more at: https://phys.org/news/2018-12-strong-interactions.html#jCp

Thursday, November 1, 2018

Verso il Dipolo


Un video costruito sul potenziale creato da due cariche finché non si arriva al dipolo.

Saturday, May 4, 2013

Nanocanyons in Multilayer Laue Lenses

Nanocanyons in Multilayer Laue Lenses

 Brookhaven National Laboratory:  A scanning electron microscope captured this from the bottom of a trench carved by reactive ion etching. 

Sunday, March 3, 2013

Physics of archaeology

"Physics is breaking new ground in the field of archaeology and human evolution.
So much so that in just a few years the gains in archaeology now equal the gains made from the past 100 years of using traditional methods, explains nuclear physicist and University of Wollongong visiting Professor Claudio Tuniz. Dr Tuniz, who began his career in the United States using physics to analyse moon rocks and meteorites, has spent almost two decades examining how advanced scientific technology in nuclear physics and X-rays can tell us more about palaeoanthropology and human evolution. ..."
more at
http://www.illawarramercury.com.au/story/1333188/hi-tech-discoveries-archaeology-transformed/?cs=12

Tuesday, July 3, 2012

Rumors

Higgs Bosons Rumors: Hopes that Cern scientists have found the Higgs Boson were strengthened yesterday when rival American researchers announced their strongest evidence yet of its existence.
http://www.telegraph.co.uk/science/large-hadron-collider/9370677/Higgs-Boson-rumours-strengthened-by-Tevatron-data.html

Friday, June 29, 2012

Small oscillations...

"Researchers Terry Hunt and Carl Lipo test a new theory that suggests how ancient Easter Islanders may have used ropes to “walk” the moai to their platforms. Mystery of Easter Island"http://ngm.nationalgeographic.com/2012/07/easter-island/walking-statue-video

Thursday, March 1, 2012

Why the Ocean is Blue?

"Why is the ocean blue? Speculation about the blue color of the ocean, as seen from above, goes way back. Lord Rayleigh claimed it was simply reflection of the blue sky. The correct explanation required combining the 19th-century ideas of Robert Bunsen, who felt that the color depended on light absorption by water, and Jacques-Louis Soret, who felt that the color was entirely due to scattering. C. V. Raman pointed out the importance of molecular scattering, and in 1923 Vasily Shuleikin combined those ideas to develop a complete explanation of the color of the sea."
In Physics Today, Shedding new light on light in the ocean
Tommy D. Dickey, George W. Kattawar, and Kenneth J. Voss
April 2011, http://dx.doi.org/10.1063/1.3580492
Recent advances are making it possible for optical oceanographers to solve a host of pressing environmental problems.

Tuesday, February 14, 2012

Flying pyramids



Intrinsic Stability of a Body Hovering in an Oscillating Airflow

Bin Liu, Leif Ristroph, Annie Weathers, Stephen Childress, and Jun Zhang
Published February 9, 2012
Synopsis: Floats Like a Pyramid, Physics, APS

"Writing in Physical Review Letters, Bin Liu and co-workers at New York University present results from experiments on an inanimate pyramid-shaped flyer, or “bug.” Their choice of the shape was made in view of previous experiments with tethered flight, which showed that pyramids could hover in an airflow."
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.108.068103

Tuesday, January 3, 2012

Cloaking objects from surface water waves

Viewpoint: Cloaking Comes Out of the Shadows, by Ross McPhedran, Alexander Movchan.
http://physics.aps.org/articles/v5/2
"Cloaking devices made of a composite of soft and hard materials can divert elastic vibrational waves around an object as though it wasn’t there. Though cloaking devices are mainly associated with hiding objects from light, the concept of cloaking is not restricted to electromagnetic waves. Experimentalists have shown they can cloak objects from surface water waves [1] and electron waves on the surface of metals (plasmons) [2]. Now, Nicolas Stenger at the Karlsruhe Institute of Technology in Germany and his colleagues have designed and tested a cloak that makes an object in a flexible medium invisible to elastic vibrational waves [3]; that is, the waves pass by the object as though it wasn’t there. The work, which is presented in Physical Review Letters, describes a cloaking device that is both more efficient and covers a wider bandwidth than any other existing cloak."

Wednesday, December 28, 2011

Centennial Superconductivity

The Japanese Journal of Applied Physics
Volume 51, Number 1, January 2012
had published the Special Section: Centennial Anniversary of Superconductivity in commemoration of the 50th anniversary of JJAP and the centennial anniversary of superconductivity.

Special Section —Centennial Anniversary of Superconductivity—
Comprehensive Review
Invited Review Papers
Selected Topics in Applied Physics
Rapid Communications
Regular Papers
Semiconductors, dielectrics, and organic materials
Photonics, quantum electronics, optics, and spectroscopy
Spintronics, superconductivity, and strongly correlated materials
Device physics
Nanoscale science and technology
Crystal growth, surfaces, interfaces, thin films, and bulk materials
Plasmas, applied atomic and molecular physics, and applied nuclear physics
Device processing, fabrication and measurement technologies, and instrumentation
Brief Notes

Tuesday, December 13, 2011

Higgs boson

"On Tuesday, physicists at the Large Hadron Collider near Geneva, Switzerland, said that data from two independent experiments had helped them narrow the range of what the mass of the Higgs boson could be. Higgs bosons—if they exist—are created in the giant atom-smashing machine, where they almost instantly decay into other particles. Discovery is based on observing the particles into which they decay.
One experiment, known as Atlas, suggested that the hypothesized Higgs is most likely to have a tiny mass, in the range of 116 to 130 gigaelectronvolts, or GeV. The other experiment pegged mass at 115 to 127 GeV. The experiments were carried out at the European particle physics laboratory CERN near Geneva."
http://online.wsj.com/article/SB10001424052970203430404577096330121408786.html
Wall Street Journal

Thursday, December 8, 2011

Acoustic freezer

Thermoacoustic engines (sometimes called "TA engines") are thermoacoustic devices which use high-amplitude sound waves to pump heat from one place to another, or conversely use a heat difference to induce high-amplitude sound waves. In general, thermoacoustic engines can be divided into standing wave and travelling wave devices. These two types of thermoacoustics devices can again be divided into two thermodynamic classes, a prime mover (or simply heat engine), and a heat pump. The prime mover creates work using heat, whereas a heat pump creates or moves heat using work. Compared to vapor refrigerators, thermoacoustic refrigerators have no ozone-depleting or toxic coolant and few or no moving parts therefore require no dynamic sealing or lubrication.
More http://en.wikipedia.org/wiki/Thermoacoustic_heat_engine

Friday, September 23, 2011

Neutrino: fast and furious

Here the news of the day!Neutrinos are faster than light!
http://www.guardian.co.uk/science/2011/sep/23/faster-light-neutrinos
"Scientists at the Opera (Oscillation Project with Emulsion-tRacking Apparatus) experiment in Gran Sasso, Italy, found that beams of neutrinos sent to its detectors from Cern, 730km away in Geneva, arrived earlier than they should have."

Thursday, September 22, 2011

Coherers as “energy catalyzers”

Coherers as “energy catalyzers”

Amelia Carolina Sparavigna
Dipartimento di Fisica,
Politecnico di Torino, Torino, Italy

Abstract: A device defined as an “energy catalyzer”, able to give thermal energy at the expense of electric energy, has aroused a great popular interest. In fact, the confidence on this device does not allow its discussion. Some known features are intriguing, which can therefore become the starting point for a discussion on old coherers and the Branly effect. We could define the coherers as a sort of “energy catalyzers”.

------------

On Wednesday September 21, 2011, from the news of RAI, the Italian broadcaster, I learned that a new device for energy production was on the way for industrial developments. I had not immediately realized the features of this device, but I memorized the fact that it was based on water, nickel powders and current, that I saw sparkling in the video clip. After searching on the Web, I found that the announced device was the energy catalyzer, E-Cat, under patent request by its inventor, Andrea Rossi. The development of prototypes was due to the work of Rossi and Sergio Focardi, University of Bologna. It seems that they have announced a device able of producing more than 10 kilowatts of heat power, while only consuming a fraction of that. "On January 14, 2011, they gave the Worlds' first public demonstration of a nickel-hydrogen fusion reactor capable of producing a few kilowatts of thermal energy. At its peak, it is capable of generating 15,000 watts with just 400 watts input required. In a following test the same output was achieved but with only 80 watts of continual input" [1]. The item is also reporting that the inventor prefers to invoke a catalyzer process, not to a cold fusion. There are so many Web pages on the E-Cat, that it is impossible to list them, but an exhaustive one is the corresponding Wikipedia item [2]. It is there that we can find the reference to the patent [3], which is about a "method and apparatus for carrying out a highly efficient exothermal reaction between nickel atoms and hydrogen atoms, in a tube, preferably, though not exclusively made of a metal, filled by a nickel powder and heated to a high temperature preferably, though not necessarily, from 150 to 5000°C, by injecting hydrogen into said metal tube said nickel powder being pressurized, preferably, though not necessarily, to a pressure from 2 to 20 bars ".


The confidence on this device does not allow its discussion. And in fact, the aim of my paper is not a discussion on E-Cat, but on what the poor information on it suggested me. Some features of the device attracted my interest: they are the metal powders, the high temperatures and the sparks of electricity. In fact I read recently about all these things together in a old book published in 1904, entitled Element of Physics, by Fernando Sanford, professor at the Stanford University, one of the members of the group of scientists who came there to create the pioneer faculty in 1891. In [4], I discussed the experiments of Sanford on the electric photography and the fact that, several years after in 1939, the fringes around the electrically photographed objects had been rediscovered by Semyon Kirlian. Of course the book written by Sanford is quite old, but, in my opinion, it has to be appreciated due to the fact that it is based on the description of experiments. The book is then quite interesting from the point of view of experimental physics and for its history. A chapter is devoted to electric radiation and electric waves. Let us remember that Fernando Sanford was talking of experiments, which, at his times were revolutionizing physics and technology. Reading the book we learn that a new device was used in laboratories, the Coherer (see Fig.1). Let me report the Laboratory Exercise 119 of the book

"Take a glass tube of about a centimeter bore and six or eight centimeters long, fit the ends with corks through which copper wires can be passed, and fill the tube between the corks with brass or iron filings. Thrust copper wires through the corks and into the iron filings until their ends are one or two centimeters apart. Connect these wires in circuit with one or more voltaic cells and a tolerably sensitive galvanometer. The resistance of the filings to the passage of a current should be so great that the galvanometer is slightly, if at all, deflected. Bring an electric machine near, and pass sparks from one discharging knob into one of the wires which enter the tube. The resistance should fall so that the galvanometer is deflected through nearly 90°. This instrument is called a Coherer. The passage of the electric discharge into the small metallic particles in the tube apparently causes them to cling together so that they make better electric contact than before. After your coherer has become sensitive enough to allow the passage of a suitable current, increase its resistance again by tapping gently on the glass and causing the particles to separate. Then move the electric machine to a distance of a few feet from the coherer and turn the handle and cause sparks to pass between the discharging knobs of the machine. If your coherer has been properly adjusted, the galvanometer will be deflected again, showing that the resistance of the coherer has been again diminished. By a little care in the adjustment, and by using a sensitive galvanometer, the coherer will respond to a spark at a distance of several yards. ... The Coherer described above is similar to the receiver used in "wireless telegraphy." The Coherer is connected between a battery and a telegraph sounder, and is attached to a long wire or other conductor suspended at some height. A similar conductor is suspended at the sending station, and is connected with the spark gap of the electric machine or induction coil. The oscillations in the receiving conductor are accordingly partly due to resonance, and they are sufficient to lower the resistance of the coherer so that a signal can be made through it. An automatic tapper jars the particles apart, so that the signal is momentary unless the instrument is sensitized by another spark. "



Fig.1. The Coherer in the book written by F. Sanford.



The device described by Sanford is a radio signal detector used in the receivers of wireless telegraphy at the beginning of the twentieth century. The coherer was invented, around 1890, by Édouard Branly [5]. As described by Sanford, it consisted of a tube or capsule containing two electrodes spaced a small distance apart, with metal filings in the space between them. To have the Branly effect, it is necessary a thin resistive layer between the grains, to have an initial high resistance. The effect is not observed with noble metal grains, cleaned from any surface contaminant. The coherer works because the metal particles cling together, that is cohere after being subjected to the radio frequency electricity. This provokes a reduction in the coherer's electrical resistance, which is persistent after the radio signal. To receive another signal, the device needs a de-coherer mechanism, able to tap the coherer, mechanically disturbing the particles and resetting them to the high resistance state. As Wikipedia [5] is telling "Coherence of particles by radio waves is an obscure phenomenon that is not well understood even today", but several recent experiments with metal particles seem to confirm that particles cohere by a micro-weld phenomenon, caused by radio frequency electricity fluxing across the small contact area between particles. This phenomenon is probably involving a tunnelling of charge carriers across an imperfect junction between conductors, as deeply discussed in Ref.6. In fact, in this reference the author is proposing to relate the Branly effect to the induced tunnelling effect first described by François Bardou and Dominique Boosé, asserting then that the effect is mainly governed by an electrical tunnel effect [7].


In the work published in 2001 [7], Bardou and Boosé theoretically proposed that the tunnelling probability of a particle through a potential barrier could be enhanced by striking the particle when the centroid of its wave packet is reflecting on the barrier. This is applied to Branly effect as discussed in [6] in the following way. “In a granular metallic medium microscopic grains are electrically isolated one from the other by a metal oxide nanometric layer ... When a voltage is applied to the medium, electrons are accelerated and they do reflect on the potential barriers. At the time of the reflection, these electrons can be kicked forward or backward by the short electromagnetic pulses present in the external electromagnetic field. … The enhanced transmission induced by the momentum transfer produces an increased electrical current, that for some events become large enough to permit a local heating in the metal grains thanks to the Joule effect. Eventually a welding of the grains can occur and when a percolation path has formed the electrical resistance of the medium drops down going from an exponential dependence on the applied voltage to a linear one”. Reference 6 is also reporting that Auerbach demonstrated in 1898 that a coherer could be made conducting by an acoustic excitation in the audible range of the spectrum. According to [6], this means that acoustical wave, by giving vibrations to tunnel barriers between the metallic grains, could be responsible of an induced tunnelling.


Let us also consider the recent experiments with particle coherers by Falcon et al. [8]. They reported on observations of the electrical transport within a chain of metallic beads, which were slightly oxidised. As the applied current is increased, a transition from an insulating to a conductive state is observed. The authors are proposing that the transition comes from an electro-thermal coupling, at the micro-contacts between each bead. Due to these contacts, the current flows through them, generating a high local heating. This heating increases the local contact areas, enhancing the conduction. This current-induced temperature rise, up to 1050°C, results in the micro-soldering of the contact points, even for low voltages.


If we define an “energy catalyzer” as a device able to produce change in, or transform energy, the coherer acts in such a manner, where the catalyst is an electromagnetic pulse. Let us hope that as soon as possible, an open report on E-Cat is published, in order to understand the role of hydrogen in it. In this device, is any tunnelling present? Is it there a tunnelling able to give a fusion of nickel and hydrogen to have copper in a proton capture as told in [9]? Is there any kicking mechanism? What we find in [9] is that the paper is just reporting the results “obtained with a process and apparatus not described here (in [9]) in detail and protected by patent in 90 countries, consisting of a system whose heat output is up to hundred times the electric energy input. As a consequence, the principle of the conservation of energy ensures that processes involving other energy forms are occurring in our apparatus”. And in the conservation of energy we trust.


References

1. http://peswiki.com/index.php/Directory:Andrea_A._Rossi_Cold_Fusion_Generator

2. http://en.wikipedia.org/wiki/Energy_Catalyzer

3. http://www.wipo.int/pctdb/en/wo.jsp?IA=IT2008000532&DISPLAY=DESC

4. A.C. Sparavigna, Fernando Sanford and the "Kirlian effect", arXiv:1105.1266v1 [physics.pop-ph], http://arxiv.org/ftp/arxiv/papers/1105/1105.1266.pdf

5. http://en.wikipedia.org/wiki/Coherer

6. C. Hirlimann, Understanding the Branly effect, arXiv:cond-mat/0703495v1 [cond-mat.mtrl-sci], http://arxiv.org/ftp/cond-mat/papers/0703/0703495.pdf

7. D. Boosé and F. Bardou, A quantum evaporation effect, Europhys. Lett., 53, 1-7 (2001).

8. E. Falcon, B. Castaing, and M. Creyssels, Nonlinear electrical conductivity in a 1D granular medium, The European Physical Journal B, 38, 475-483 (2004)

9. S. Focardi and A. Rossi, A new energy source from nuclear fusion, http://www.lenr-canr.org/acrobat/FocardiSanewenergy.pdf