Oct 28, 2020 11:07 PM
(This post was last modified: Oct 28, 2020 11:08 PM by C C.)
Physicists circumvent centuries-old theory to cancel magnetic fields
https://www.eurekalert.org/pub_releases/...102820.php
INTRO: A team of scientists including two physicists at the University of Sussex has found a way to circumvent a 178-year old theory which means they can effectively cancel magnetic fields at a distance. They are the first to be able to do so in a way which has practical benefits. The work is hoped to have a wide variety of applications. For example, patients with neurological disorders such as Alzheimer's or Parkinson's might in future receive a more accurate diagnosis. With the ability to cancel out 'noisy' external magnetic fields, doctors using magnetic field scanners will be able to see more accurately what is happening in the brain. The study "Tailoring magnetic fields in inaccessible regions" is published in Physical Review Letters... (MORE)
Cracks are appearing in the 2nd law of thermodynamics
https://medium.com/the-infinite-universe...d03177cca3
EXCERPTS: . . . In the last 25 year or so, we have seen the beginnings of technology at the nano-scale being developed that will at long last enable us to create Maxwell’s demon. These 2nd law-violating technologies can exist because the 2nd law of thermodynamics is a statistical law that can be violated for small amounts of time. Indeed, the fluctuation theorem tells us exactly how likely the 2nd law is to be violated.
What this looks like on the nano-scale is that processes usually move forward in time but sometimes appear to move backwards in time. While your broken teacup will never leap up and reassemble itself in your hand, a nano-scale teacup made of only a handful of atoms just might do so before falling over and smashing again. This new science of stochastic thermodynamics has profound implications for information theory as well because it indicates that it is possible to both measure and control nano-scale particles that are experiencing random, i.e., Brownian, motion just like Maxwell’s demon.
Consider a more modern thought experience called the Szilard engine proposed back in 1929 by Szilard, a student of Albert Einstein. [...] Recent experiments have realized Szilard’s thought experiment using a single electron and a voltage gate that controls the electron position and monitored by a single electron transistor.
They can also be realized using long colloidal particles in two optical traps (laser traps). Using electrostatic voltages, the particle can be biased to one or the other trap. Unlike the electron which has an uncertain position, we can detect the particle position inside the traps. The particle is measured and then the traps biased one way or another based on the measurement.
Other realizations have all come out in the last five years, showing the intense interest in 2nd law “violations” and opening the door to nanotechnology based on stochastic thermodynamic principles. In a dynamical information flow model, we can even now understand how information flows back and forth between two systems and understand the true physical nature of information{*} and how to extract work from systems that we previously thought were just reservoirs of heat energy... (MORE - details)
PAPER: Sagawa, Takahiro, and Masahito Ueda. “Fluctuation theorem with information exchange: Role of correlations in stochastic thermodynamics.” Physical review letters 109.18 (2012): 180602.
- - - footnote - - -
{*} Rival view, "Information is not physical"(PDF): The title of this essay is obviously polemic with the title of the first Section "Information is physical" of the famous Rolf Landauer’s paper "The physical nature of information". This paper was quite influential and stimulated, among the others, the modern advances in the study of relations between information theory and thermodynamics. The new wave of research is parallel to the rapid development of “quantum information” and “quantum computing” (although Landauer himself was quite skeptical about the latter). The aim of my note is to challenge the popular opinions concerning relations between physics and information theory. In particular, I would like to present the following thesis and support at least some of them by suitable models... --Robert Alicki
https://www.eurekalert.org/pub_releases/...102820.php
INTRO: A team of scientists including two physicists at the University of Sussex has found a way to circumvent a 178-year old theory which means they can effectively cancel magnetic fields at a distance. They are the first to be able to do so in a way which has practical benefits. The work is hoped to have a wide variety of applications. For example, patients with neurological disorders such as Alzheimer's or Parkinson's might in future receive a more accurate diagnosis. With the ability to cancel out 'noisy' external magnetic fields, doctors using magnetic field scanners will be able to see more accurately what is happening in the brain. The study "Tailoring magnetic fields in inaccessible regions" is published in Physical Review Letters... (MORE)
Cracks are appearing in the 2nd law of thermodynamics
https://medium.com/the-infinite-universe...d03177cca3
EXCERPTS: . . . In the last 25 year or so, we have seen the beginnings of technology at the nano-scale being developed that will at long last enable us to create Maxwell’s demon. These 2nd law-violating technologies can exist because the 2nd law of thermodynamics is a statistical law that can be violated for small amounts of time. Indeed, the fluctuation theorem tells us exactly how likely the 2nd law is to be violated.
What this looks like on the nano-scale is that processes usually move forward in time but sometimes appear to move backwards in time. While your broken teacup will never leap up and reassemble itself in your hand, a nano-scale teacup made of only a handful of atoms just might do so before falling over and smashing again. This new science of stochastic thermodynamics has profound implications for information theory as well because it indicates that it is possible to both measure and control nano-scale particles that are experiencing random, i.e., Brownian, motion just like Maxwell’s demon.
Consider a more modern thought experience called the Szilard engine proposed back in 1929 by Szilard, a student of Albert Einstein. [...] Recent experiments have realized Szilard’s thought experiment using a single electron and a voltage gate that controls the electron position and monitored by a single electron transistor.
They can also be realized using long colloidal particles in two optical traps (laser traps). Using electrostatic voltages, the particle can be biased to one or the other trap. Unlike the electron which has an uncertain position, we can detect the particle position inside the traps. The particle is measured and then the traps biased one way or another based on the measurement.
Other realizations have all come out in the last five years, showing the intense interest in 2nd law “violations” and opening the door to nanotechnology based on stochastic thermodynamic principles. In a dynamical information flow model, we can even now understand how information flows back and forth between two systems and understand the true physical nature of information{*} and how to extract work from systems that we previously thought were just reservoirs of heat energy... (MORE - details)
PAPER: Sagawa, Takahiro, and Masahito Ueda. “Fluctuation theorem with information exchange: Role of correlations in stochastic thermodynamics.” Physical review letters 109.18 (2012): 180602.
- - - footnote - - -
{*} Rival view, "Information is not physical"(PDF): The title of this essay is obviously polemic with the title of the first Section "Information is physical" of the famous Rolf Landauer’s paper "The physical nature of information". This paper was quite influential and stimulated, among the others, the modern advances in the study of relations between information theory and thermodynamics. The new wave of research is parallel to the rapid development of “quantum information” and “quantum computing” (although Landauer himself was quite skeptical about the latter). The aim of my note is to challenge the popular opinions concerning relations between physics and information theory. In particular, I would like to present the following thesis and support at least some of them by suitable models... --Robert Alicki