Wednesday, October 31, 2012
Tuesday, October 23, 2012
Lagrange Bracket- K A Solaman
Lagrange Bracket
![Contribute to this entry](http://mathworld.wolfram.com/images/entries/contribute2.gif)
Let
be any functions of two variables
. Then the expression
![(q_1,...,q_n,p_1,...,p_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline1.gif)
![(u,v)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline2.gif)
![]() |
(1)
|
is called a Lagrange bracket (Lagrange 1808; Whittaker 1944, p. 298).
The Lagrange brackets are anticommutative,
![]() |
(2)
|
(Plummer 1960, p. 136).
If
are any functions of
variables
, then
![(q_1,...,q_n,p_1,...,p_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline3.gif)
![2n](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline4.gif)
![(Q_1,...,Q_n,P_1,...,P_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline5.gif)
![]() |
(3)
|
where the summation on the right-hand side is taken over all pairs of variables
in the set
.
![(u_k,u_l)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline6.gif)
![(Q_1,...,Q_n,P_1,...,P_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline7.gif)
But if the transformation from
to
is a contact transformation, then
![(q_1,...,q_n,p_1,...,p_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline8.gif)
![(Q_1,...,Q_n,P_1,...,P_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline9.gif)
![]() |
(4)
|
giving
![]() | ![]() | ![]() |
(5)
|
![]() | ![]() | ![]() |
(6)
|
![]() | ![]() | ![]() |
(7)
|
![]() | ![]() | ![]() |
(8)
|
Furthermore, these may be regarded as partial differential equations which must be satisfied by
, considered as function of
in order that the transformation from one set of variables to the other may be a contact transformation.
![(q_1,...,q_n,p_1,...,p_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline22.gif)
![(Q_1,...,Q_n,P_1,...,P_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline23.gif)
Let
be
independent functions of the variables
. Then the Poisson bracket
is connected with the Lagrange bracket
by
![(u_1,...,u_(2n))](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline24.gif)
![2n](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline25.gif)
![(q_1,...,q_n,p_1,...,p_n)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline26.gif)
![(u_r,u_s)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline27.gif)
![[u_r,u_s]](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline28.gif)
![]() |
(9)
|
where
is the Kronecker delta. But this is precisely the condition that the determinants formed from them are reciprocal (Whittaker 1944, p. 300; Plummer 1960, p. 137).
![delta_(rs)](http://mathworld.wolfram.com/images/equations/LagrangeBracket/Inline29.gif)
SEE ALSO:
Tuesday, October 09, 2012
Quantum physicists win 2012 Physics Nobel prize
Serge Haroche of France and American David Wineland opened the door to new experiments in quantum physics by showing how to observe individual quantum particles while preserving their quantum properties.
A quantum particle is one that is isolated from everything else. In this situation, an atom or electron or photon takes on strange properties. It can be in two places at once, for example. It behaves in some ways like a wave. But these properties are instantly changed when it interacts with something else, such as when somebody observes it.
Working separately, the two scientists, both 68, developed "ingenious laboratory methods" that allowed them to manage and measure and control fragile quantum states, the Royal Swedish Academy of Sciences said.
"Their ground-breaking methods have enabled this field of research to take the very first steps towards building a new type of superfast computer based on quantum physics," the academysaid. "The research has also led to the construction of extremely precise clocks that could become the future basis for a new standard of time."
Haroche is a professor at the College de France and Ecole Normale Superieure in Paris. Wineland is a physicist at the National Institute of Standards and Technology, or NIST, and the University of Colorado in Boulder, Colorado. The two researchers use opposite approaches to examine, control and count quantum particles, the academy said. Wineland traps ions - electrically charged atoms - and measures them with light, while Haroche controls and measures photons, or light particles.
Haroche said he was out walking with his wife when he got the call from Nobel judges. "I was in the street and passing a bench so I was able to sit down," Haroche told a news conference inStockholm by phone. "It's very overwhelming." He said his work in the realm of quantum physics could ultimately lead to unimaginably fast computers.
ഭൌതിക ശാസ്ത്രത്തിനുള്ള നൊബെല് സെര്ജെയും വിന്ഫീല്ഡും പങ്കിട്ടു
![](http://www.janmabhumidaily.com/jnb/wp-content/uploads/2012/10/nobel-prize1.jpg)
ക്വാണ്ടം ഒപ്റ്റിക്സിന്റെ പഠനത്തില് ഇരുവരും പുതിയ വാതായനങ്ങള് തുറന്നതായി റോയല് സ്വീഡിഷ് അക്കാദമി വാര്ത്താക്കുറിപ്പില് വ്യക്തമാക്കി. സ്വതന്ത്രമായ ഊര്ജകണങ്ങളെ അവയെ നശിപ്പിക്കാതെ തന്നെ കണ്ടെത്തുന്ന പരീക്ഷണമാണ് ഇരുവരും നടത്തിയത്.
ഗവേഷകര് നേരത്തെ അസാധ്യമെന്ന് വിധിയെഴുതിയ കാര്യമായിരുന്നു ഇത്. പുതിയ സൂപ്പര് ഫാസ്റ്റ് കംപ്യൂട്ടറുകള് പോലും നിര്മിക്കാന് സഹായകമാകുന്ന കണ്ടുപിടുത്തമാണ് ഇവരുടേത്.
Comment: Fascinating Physics!
-K A Solaman
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