Physicks

Thu Jan 07, 2016 5:30 pm

Physicκs
General Topic about
"Natural philosophy"

Library

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Tue Jan 12, 2016 12:16 am

Basic idea:
Physical models are mathematical, but mathematics is not what
they are based on. The quantitative relations between physical
quantities are clarified through measurements, observations and
experimental investigations. Mathematics only serves as the
language in which these relations are expressed. There is no
other language for constructing physical theories.

ΒΑΣΙΚΗ ΙΔΕΑ
ΤΑ ΦΥΣΙΚΑ Πρότυπα είναι μαθηματικά - άλλα δεν βασίζονται
στα μαθηματικά. Οι ποσοτικές σχέσεις μεταξύ φυσικών μεγεθών
καθορίζονται απο τις μετρήσεις - πάντα μέσω προσεχτικής
παρατήρησης και πειραματικής έρευνας. Τα Μαθηματικά είναι
το όργανο για την περιγραφή αυτών των συναρτήσεων.
There is no royal road to Geometry.
There is a Rose in Spansih Harlem.

Tue Jan 12, 2016 2:18 am

Links.

http://arxiv.org/

Physicks 655564803

papers
http://arxiv.org/list/gr-qc/new

Living Physicks 3565688305

Reviews
in relativity
http://relativity.livingreviews.org/

The Max Planck Institute for Gravitational Physics
http://www.aei.mpg.de/

nature physics :
http://www.nature.com/nphys/index.html

Webpages :
http://hyperphysics.phy-astr.gsu.edu
http://www.physics.org/
http://www.physicscentral.com/

Physicks Flp10

http://www.feynmanlectures.caltech.edu/

Tue Jan 12, 2016 2:33 am

Inside Black Holes Physicks 3213635679

http://jila.colorado.edu/~ajsh/insidebh/intro.html

[This is not an artist's impression.
It is a general relativistic volume-rendering
of a super-computed simulation.]
Physicks 3833324623

Larger version
-
Andrew Hamilton's Homepage

Fri Feb 12, 2016 5:34 pm

Edwin F. Taylor's Website
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http://www.black-holes.org
Simulating eXtreme Spacetimes

Fri Apr 01, 2016 3:31 pm

The animations above illustrate the typical four-dimensional structure of gluon-field
configurations averaged over in describing the vacuum properties of QCD. The volume
of the box is 2.4 by 2.4 by 3.6 fm, big enough to hold a couple of protons.

http://www.physics.adelaide.edu.au/theory/staff/leinweber/VisualQCD/Nobel
[High quality animations are available]

Thu Apr 21, 2016 11:46 am

Everyone’s a Critic
Physicks 975810733

Preposterous Universe (Carroll 2014)

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Code:: When you play, you don't ask "why" you are playing – you just play. Play serves no moral code except that strange code which, for some reason, imposes itself on the play.... You will search in vain - through scientifick literature for hints of motivation. And as for the strange "code" observed by scientists, what could be stranger than an abstract regard for truth in a world which is full of concealment, deception, and taboos? … In submitting to your consideration the idea that the mind is at its best when playing, I am myself playing, and that makes me feel that what I am saying may have an element of truth..

Sat May 27, 2017 10:00 am

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Physicks 94b4ef10

Quantum Physics Thread Physicks 655564803

Mon Jun 05, 2017 5:35 pm

Gravitational lensing by a non-rotating black hole
Combining electromagnetism with relativity and quantum mechanics led to QED.
But combining gravity with relativity led Einstein to something equally interesting : general relativity.
General relativity does not take quantum mechanics into account, so the story is not yet over. Many Colleagues hope that quantum
gravity will eventually save physics from its struggles with the continuum! Since quantum gravity far from being understood, this
remains just a hope. This hope has motivated a profusion of new ideas on spacetime.

Tolman–Oppenheimer–Volkoff limit
Above this limit, gravity overwhelms the repulsive forces that hold up the neutron star. And indeed, no neutron stars heavier than 3 solar masses have been observed. Thus, for very heavy stars, the endpoint of collapse is not a neutron star, but something else: a black hole, an object that bends spacetime so much even light cannot escape.
If general relativity is correct, a black hole contains a singularity. Many physicists expect that general relativity breaks down inside a black hole, perhaps because of quantum effects that become important at strong gravitational fields. The singularity is considered a strong hint that this breakdown occurs. If so, the singularity may be a purely theoretical entity, not a real-world phenomenon. Nonetheless, everything we have observed about black holes matches what general relativity predicts. Thus, unlike all the other theories we have discussed, general relativity predicts "infinities" that are connected to striking phenomena that are actually observed.
The Tolman–Oppenheimer–Volkoff limit is not precisely known, because it depends on properties of nuclear matter that are not well understood. However, there are theorems that say singularities must occur in general relativity under certain conditions.
One of the first was proved by Raychauduri and Komar in the mid-1950’s. It applies only to ‘dust’, and indeed it is a precise version of our verbal argument above. It introduced the Raychauduri’s equation, which is the geometrical way of thinking about spacetime curvature as affecting the motion of a small ball of test particles. It shows that under suitable conditions, the energy density must approach infinity in a finite amount of time along the path traced out out by a dust particle.
The first required condition is that the flow of dust be initally converging, not expanding. The second condition, not mentioned in our verbal argument, is that the dust be ‘irrotational’, not swirling around. The third condition is that the dust particles be affected only by gravity, so that they move along geodesics. Due to the last two conditions, the Raychauduri–Komar theorem does not apply to collapsing stars.
The more modern singularity theorems eliminate these conditions. But they do so at a price: they require a more subtle concept of singularity! There are various possible ways to define this concept. They’re all a bit tricky, because a singularity is not a point or region in spacetime.
For our present purposes, we can define a singularity to be an ‘incomplete timelike or null geodesic’. As already explained, a timelike geodesic is the kind of path traced out by a test particle moving slower than light. Similarly, a null geodesic is the kind of path traced out by a test particle moving at the speed of light. We say a geodesic is ‘incomplete’ if it ceases to be well-defined after a finite amount of time. For example, general relativity says a test particle falling into a black hole follows an incomplete geodesic. In a rough-and-ready way, people say the particle ‘hits the singularity’. But the singularity is not a place in spacetime. What we really mean is that the particle’s path becomes undefined after a finite amount of time.
We need to be a bit careful about what we mean by ‘time’ here. For test particles moving slower than light this is easy, since we can parametrize a timelike geodesic by proper time. However, the tangent vector $Physicks Latex$ of a null geodesic has $Physicks Latex$ so a particle moving along a null geodesic does not experience any passage of proper time. Still, any geodesic, even a null one, has a family of preferred parametrizations. These differ only by changes of variable like this: $Physicks Latex.php?latex=s+%5Cmapsto+as+%2B+b$ By ‘time’ we really mean the variable $Physicks Latex$ in any of these preferred parametrizations. Thus, if our spacetime is some Lorentzian manifold $Physicks Latex$ we say a geodesic $Physicks Latex$ is incomplete if, parametrized in one of these preferred ways, it cannot be extended to a strictly longer interval.
The first modern singularity theorem was proved by Penrose in 1965. It says that if space is infinite in extent, and light becomes trapped inside some bounded region, and no exotic matter is present to save the day, either a singularity or something even more bizarre must occur. This theorem applies to collapsing stars. When a star of sufficient mass collapses, general relativity says that its gravity becomes so strong that light becomes trapped inside some bounded region. We can then use Penrose’s theorem to analyze the possibilities.
Shortly thereafter Hawking proved a second singularity theorem, which applies to the Big Bang. It says that if space is finite in extent, and no exotic matter is present, generically either a singularity or something even more bizarre must occur. The singularity here could be either a Big Bang in the past, a Big Crunch in the future, both—or possibly something else. Hawking also proved a version of his theorem that applies to certain Lorentzian manifolds where space is infinite in extent, as seems to be the case in our Universe. This version requires extra conditions.

Thu Mar 21, 2019 9:30 pm

Andreas Albrecht [Can the universe afford inflation?] 2004

https://arxiv.org/abs/hep-th/0405270

-- Boltzmann’s original paper! Nature 51, 415 [1895]

We assume that the whole universe is, and rests for ever, in thermal equilibrium. The probability that one (only one)
part of the universe is in a certain state, is the smaller the further this state is from thermal equilibrium; but this probability
is greater, the greater is the universe itself. If we assume the universe great enough, we can make the probability of one
relatively small part being in any given state (however far from the state of thermal equilibrium), as great as we please.
We can also make the probability great that, though the whole universe is in thermal equilibrium, our world is in its
present state. It may be said that the world is so far from thermal equilibrium that we cannot imagine the
improbability of such a state. But can we imagine, on the other side, how small a part of the whole universe
this world is? Assuming the universe great enough, the probability that such a small part of it as our world
should be in its present state, is no longer small. If this assumption were correct, our world would return
more and more to thermal equilibrium; but because the whole universe is so great, it might be probable
that at some future time some other world might deviate as far from thermal equilibrium as our world does
at present. Then the afore-mentioned H-curve would form a representation of what takes place in the universe.
The summits of the curve would represent the worlds where visible motion and life exist.

English translation from Latin :
For certainly neither did the first-beginnings
. place themselves by design each in its own order
nor assuredly did they make agreement what motions each should produce; but because, being many [the Atoms]
and shifted in many ways, they are harried and set in motion with blows throughout the universe from infinity,
thus by trying every kind of motion and combination, at length they fall into such arrangements as this sum of things
consists and this being also preserved through many great cycles of years, when once it has been cast.
from DE RERUM NATURA Lucretius , Loeb Classical Library

Thu Aug 20, 2020 4:00 pm

Οn Zermelo's Paper : "On the Mechanical Explanation of Irreversible Processes"
Ludwig Boltzmann :

SUMMARY :

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Vienna 16 Dec . 1896

Thu Aug 20, 2020 4:00 pm

https://planetmath.org/PoincareRecurrenceTheorem

Physicks 739989325

Hamiltonian system with a finite accessible phase space, the system will return to the proximity of a generic initial state infinitely many times.
( irreversible processes are impossible in a mechanical world. )

[1]. Sur le problème des trois corps et les équations de la dynamique, par H. Poincaré 1890 / Acta. Math. Volume 13, p. 1–270
[2]. Gibbs, Josiah Willard Elementary Principles in Statistical Mechanics. New York, (1902). Chapter X , XII
https://archive.org/details/elementaryprinc00gibbgoog/page/n10/mode/2up
[3]. Carathéodory C., Über den Wiederkehrsatz von Poincaré, (1919) p580–584.
[4]. A.Ya. Khinchin, "Eine Verschärfung des Poincaréschen Wiederkehrsatzes" Comp. Math. , 1 (1934) pp. 177–179

Physicks 34382612

Pendulum Waves with Philip Glass

Thu Aug 20, 2020 4:00 pm

Physicks is Not a Subject.
the Great Physical World
is the Only World there is.
Every Metaphysics is nothing
but a misconception and a
complete waste of time.
dreams of ghosts and
misconceptions
are too : all Natural.

Fri Oct 01, 2021 3:00 pm

Recurrences in an isolated quantum many-body system :

Physicks 3397135517

https://arxiv.org/pdf/1705.08231.pdf

Fri Oct 01, 2021 3:00 pm

If you want to learn about nature, to appreciate nature, it is necessary to understand the language that she speaks in.
chapter 2, “The Relation of Mathematics to Physics,” p. 58

Philosophy is written in this grand book, which ever lies open before our eyes (I say the 'Universe'),
but can not be understood without first learning to comprehend the language and know the characters as it is written.
It is written in mathematical language, and its characters are triangles, circles and other geometric figures, without which
it is impossible to understand a single word ; without these one wanders in vain in a dark labyrinth.

from il Saggiatore , 1623

La filosofia è scritta in questo grandissimo libro, che continuamente ci sta aperto innanzi agli occhi (io dico l'Universo) , ma non si può intendere,
se prima non il sapere a intender la lingua, e conoscer i caratteri ne quali è scritto. Egli è scritto in lingua matematica, e i caratteri son triangoli,
cerchi ed altre figure geometriche, senza i quali mezzi è impossibile intenderne umanamente parola; senza questi è un aggirarsi vanamente
per un oscuro labirinto.

Fri Oct 01, 2021 3:00 pm

Physicks

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Basic Idea , Matveev A.N.

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Visualizations of Quantum Chromodynamics (QCD)

Big Bang / Current Research

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Struggles with the Continuum

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Οn Zermelo's Paper / Ludwig Boltzmann 1896

Poincaré recurrence theorem

Ph.

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