Friday, July 26, 2013
Tuesday, July 23, 2013
Friday, June 14, 2013
Thursday, January 10, 2013
History of solar wind and space plasma physics revisited. (arXiv:1301.1971v1 [physics.hist-ph])
History of solar wind and space plasma physics revisited. (arXiv:1301.1971v1 [physics.hist-ph]):
A paper published by Scottish geophysicist J.A. Broun in 1858 contained
several pioneering and remarkable ideas in solar-terrestrial physics. He could
anticipate more or less correctly the nature and origin of solar wind, solar
magnetic fields, sunspot activity and geomagnetic storms in the middle of the
19th century. Broun applied the experimental results of the behavior of ionized
gases in discharge tubes for the first time to Space Physics which may be
considered as the beginning of the astrophysical plasma physics. In this
context he attempted to explain the plasma interactions of solar wind with the
comet tails and earth's magnetosphere. Most of the postulates or hypotheses put
forward by Broun in 1858 and later in 1874 was rediscovered during the 20th
century, after the advent of Space age.
A paper published by Scottish geophysicist J.A. Broun in 1858 contained
several pioneering and remarkable ideas in solar-terrestrial physics. He could
anticipate more or less correctly the nature and origin of solar wind, solar
magnetic fields, sunspot activity and geomagnetic storms in the middle of the
19th century. Broun applied the experimental results of the behavior of ionized
gases in discharge tubes for the first time to Space Physics which may be
considered as the beginning of the astrophysical plasma physics. In this
context he attempted to explain the plasma interactions of solar wind with the
comet tails and earth's magnetosphere. Most of the postulates or hypotheses put
forward by Broun in 1858 and later in 1874 was rediscovered during the 20th
century, after the advent of Space age.
FLASHBACK: WHAT THE FOUNDING FATHERS SAID ABOUT GUNS
FLASHBACK: WHAT THE FOUNDING FATHERS SAID ABOUT GUNS:
Militias. Distrust of government. Abuse of power. The right to bear arms. Not a day passed without a passionate article or an editorial on the role of guns in American life. The year was 1775. More than 200 years later, the seminal debate undertaken as John Adams, Thomas Jefferson and James Madison formulated the laws of the land still echoes. Is the Michigan Militia an aberration or the Constitution in action? Is Gordon Liddy a dangerous demagogue or a devoted patriot? What exactly did the founding fathers mean when they penned the Second Amendment? No sampler can do justice to the debate, but we hope the following scrapbook helps shed light on the relation between arms and liberty. Our sources were Alexander Hamilton, Madison and John Jay's Federalist, "That Every Man Be Armed: The Evolution of a Constitutional Right," by Stephen Halbrook, "The Road to the Bill of Rights," by Craig Smith, and a collection of quotes compiled by Charles Curley.
Militias. Distrust of government. Abuse of power. The right to bear arms. Not a day passed without a passionate article or an editorial on the role of guns in American life. The year was 1775. More than 200 years later, the seminal debate undertaken as John Adams, Thomas Jefferson and James Madison formulated the laws of the land still echoes. Is the Michigan Militia an aberration or the Constitution in action? Is Gordon Liddy a dangerous demagogue or a devoted patriot? What exactly did the founding fathers mean when they penned the Second Amendment? No sampler can do justice to the debate, but we hope the following scrapbook helps shed light on the relation between arms and liberty. Our sources were Alexander Hamilton, Madison and John Jay's Federalist, "That Every Man Be Armed: The Evolution of a Constitutional Right," by Stephen Halbrook, "The Road to the Bill of Rights," by Craig Smith, and a collection of quotes compiled by Charles Curley.
Monday, December 17, 2012
They're catching on, slowly.
Phys.org (@physorg_com) tweeted at 3:38 PM on Mon, Dec 17, 2012: Study confirms 'gusty winds' in #space #turbulence http://t.co/KL4CFgCq @uiowa (https://twitter.com/physorg_com/status/280789082014101505) Get the official Twitter app at https://twitter.com/download
Wednesday, December 5, 2012
Wednesday, November 28, 2012
Illuminating Fourier Series with Audacity. (arXiv:1211.4832v1 [physics.ed-ph])
Illuminating Fourier Series with Audacity. (arXiv:1211.4832v1 [physics.ed-ph]):
This paper briefly describes some simple techniques for illuminating Fourier
series and Fourier analysis with the Audacity sound recording program. These
techniques are easily applied in the classroom and help students move beyond
formula roulette in their understanding of Fourier techniques.
This paper briefly describes some simple techniques for illuminating Fourier
series and Fourier analysis with the Audacity sound recording program. These
techniques are easily applied in the classroom and help students move beyond
formula roulette in their understanding of Fourier techniques.
A short introduction to the quantum formalism[s]. (arXiv:1211.5627v1 [math-ph])
A short introduction to the quantum formalism[s]. (arXiv:1211.5627v1 [math-ph]):
These notes are an elaboration on: (i) a short course that I gave at the
IPhT-Saclay in May-June 2012; (ii) a previous letter on reversibility in
quantum mechanics. They present an introductory, but hopefully coherent, view
of the main formalizations of quantum mechanics, of their interrelations and of
their common physical underpinnings: causality, reversibility and
locality/separability. The approaches covered are mainly: (ii) the canonical
formalism; (ii) the algebraic formalism; (iii) the quantum logic formulation.
Other subjects: quantum information approaches, quantum correlations,
contextuality and non-locality issues, quantum measurements, interpretations
and alternate theories, quantum gravity, are only very briefly and
superficially discussed. Most of the material is not new, but is presented in
an original, homogeneous and hopefully not technical or abstract way. I try to
define simply all the mathematical concepts used and to justify them
physically. These notes should be accessible to young physicists (graduate
level) with a good knowledge of the standard formalism of quantum mechanics,
and some interest for theoretical physics (and mathematics). These notes do not
cover the historical and philosophical aspects of quantum physics.
These notes are an elaboration on: (i) a short course that I gave at the
IPhT-Saclay in May-June 2012; (ii) a previous letter on reversibility in
quantum mechanics. They present an introductory, but hopefully coherent, view
of the main formalizations of quantum mechanics, of their interrelations and of
their common physical underpinnings: causality, reversibility and
locality/separability. The approaches covered are mainly: (ii) the canonical
formalism; (ii) the algebraic formalism; (iii) the quantum logic formulation.
Other subjects: quantum information approaches, quantum correlations,
contextuality and non-locality issues, quantum measurements, interpretations
and alternate theories, quantum gravity, are only very briefly and
superficially discussed. Most of the material is not new, but is presented in
an original, homogeneous and hopefully not technical or abstract way. I try to
define simply all the mathematical concepts used and to justify them
physically. These notes should be accessible to young physicists (graduate
level) with a good knowledge of the standard formalism of quantum mechanics,
and some interest for theoretical physics (and mathematics). These notes do not
cover the historical and philosophical aspects of quantum physics.
Tuesday, November 27, 2012
Solving for three-dimensional central potentials using matrix mechanics. (arXiv:1211.5236v1 [physics.class-ph])
Solving for three-dimensional central potentials using matrix mechanics. (arXiv:1211.5236v1 [physics.class-ph]):
Matrix mechanics is an important component of an undergraduate education in
quantum mechanics. Unfortunately it is generally taught only in the abstract,
with real implementations relegated to more advanced degrees, and usually in
the context of many-body physics. In this paper we present several examples of
the use of matrix mechanics to solve for a number of three dimensional problems
involving central forces. These include examples with which the student is
familiar, such as the Coulomb interaction -- in this case we obtain excellent
agreement with exact analytical methods, -- along with other interesting
`non-solvable' examples, such as the Yukawa potential. Much less mathematical
expertise is required for these methods, while some minimal familiarity with
the usage of numerical diagonalization software is necessary.
Matrix mechanics is an important component of an undergraduate education in
quantum mechanics. Unfortunately it is generally taught only in the abstract,
with real implementations relegated to more advanced degrees, and usually in
the context of many-body physics. In this paper we present several examples of
the use of matrix mechanics to solve for a number of three dimensional problems
involving central forces. These include examples with which the student is
familiar, such as the Coulomb interaction -- in this case we obtain excellent
agreement with exact analytical methods, -- along with other interesting
`non-solvable' examples, such as the Yukawa potential. Much less mathematical
expertise is required for these methods, while some minimal familiarity with
the usage of numerical diagonalization software is necessary.
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