Search results for "Einstein"

Mass and Gravity

2014

The book starts with a survey on the development of the concept ‘mass’ and of theories of gravity, beginning with Greek’s ideas on mass, Galileo’s experiments, Newton’s laws and their extension by Einstein’s theory of relativity. Data from measurements of the gravitational force on Sun, planets and the Moon are presented. Kepler’s laws on moving masses in the gravitational field are discussed as well as new discoveries on the expansion of the universe. Fundamental interactions of particles and particle/wave duality are described. The Theory of Everything is mentioned. The definition of the international unit of mass is reported as well as alternatives like watt or voltage balance, counting …

Unveiling two-dimensional discrete quantum walks dynamics via dispersion relations

2011

The discrete, or coined, quantum walk (QW) [1] is a process originally introduced as the quantum counterpart of the classical random walk (RW). In both cases there is a walker and a coin: at every time step the coin is tossed and the walker moves depending on the toss output. Unlike the RW, in the QW the walker and coin are quantum in nature what allows the coherent superpositions right/left and head/tail happen. This feature endows the QW with outstanding properties, such as making the standard deviation of the position of an initially localized walker grow linearly with time t, unlike the RW in which this growth goes as t1/2. This has strong consequences in algorithmics and is one of the …

Experimental demonstration of single-site addressability in a two-dimensional optical lattice

2009

We demonstrate single site addressability in a two-dimensional optical lattice with 600 nm lattice spacing. After loading a Bose-Einstein condensate in the lattice potential we use a focused electron beam to remove atoms from selected sites. The patterned structure is subsequently imaged by means of scanning electron microscopy. This technique allows us to create arbitrary patterns of mesoscopic atomic ensembles. We find that the patterns are remarkably stable against tunneling diffusion. Such micro-engineered quantum gases are a versatile resource for applications in quantum simulation, quantum optics and quantum information processing with neutral atoms.

Quantum Criticality in a Bosonic Josephson Junction

2011

In this paper we consider a bosonic Josephson junction described by a two-mode Bose-Hubbard model, and we thoroughly analyze a quantum phase transition occurring in the system in the limit of infinite bosonic population. We discuss the relation between this quantum phase transition and the dynamical bifurcation occurring in the spectrum of the Discrete Self Trapping equations describing the system at the semiclassical level. In particular, we identify five regimes depending on the strength of the effective interaction among bosons, and study the finite-size effects arising from the finiteness of the bosonic population. We devote a special attention to the critical regime which reduces to th…

Tunable Polarons in Bose-Einstein Condensates

2017

A toolbox for the quantum simulation of polarons in ultracold atoms is presented. Motivated by the impressive experimental advances in the area of ultracold atomic mixtures, we theoretically study the problem of ultracold atomic impurities immersed in a Bose-Einstein condensate mixture (BEC). The coupling between impurity and BEC gives rise to the formation of polarons whose mutual interaction can be effectively tuned using an external laser driving a quasi-resonant Raman transition between the BEC components. Our scheme allows one to change the effective interactions between polarons in different sites from attractive to zero. This is achieved by simply changing the intensity and the frequ…

Conscious Machines: A Possibility? If So, How?

2020

The scope of the paper is to encourage scientists and engineering to avoid to do what Einstein pointed out as being the hallmark of folly. Machine consciousness scholars must be brave enough to step out of the beaten path. There must be some big recurrent conceptual mistakes that prevent science and technology from addressing machine consciousness.

Alcune considerazioni sulla conversazione di Popper con “Parmenide”

Although Popper contributed significantly to the doctrinal recovery of the so-called second part of the Parmenidean poem, his overall interpretation of Parmenides' thought nevertheless strengthened the traditional thesis that sees Parmenides as the father of metaphysics. It is quite well known, in fact, that Popper assimilated the Parmenidean doctrine of being to Einstein's theory of relativity, combining them both under the "label" of "Methaphysical Determinism". It is also known that Popper says he spoke directly with Einstein about this interpretative hypothesis - in a conversation in which he would have called him, precisely, "Parmenides" - and that the scientist had agreed enough with …

Coxeter on People and Polytopes

2004

H. S. M. Coxeter, known to his friends as Donald, was not only a remarkable mathematician. He also enriched our historical understanding of how classical geometry helped inspire what has sometimes been called the nineteenth-century’s non-Euclidean revolution (Fig. 35.1). Coxeter was no revolutionary, and the non-Euclidean revolution was already part of history by the time he arrived on the scene. What he did experience was the dramatic aftershock in physics. Countless popular and semi-popular books were written during the early 1920s expounding the new theory of space and time propounded in Einstein’s general theory of relativity. General relativity and subsequent efforts to unite gravitati…

Einstein-Smoluchowsky equation handled by complex fractional moments

2014

In this paper the response of a non linear half oscillator driven by α-stable white noise in terms of probability density function (PDF) is investigated. The evolution of the PDF of such a system is ruled by the so called Einstein-Smoluchowsky equation involving, in the diffusive term, the Riesz fractional derivative. The solution is obtained by the use of complex fractional moments of the PDF, calculated with the aid of Mellin transform operator. It is shown that solution can be found for various values of stability index α and for any nonlinear function of the drift term in the stochastic differential equation.

Winteler, Jost (1846–1929)

2006

J Winteler was born in a village in the Swiss canton of Glarus. He studied philology in Jena, Germany. In his famous doctoral thesis, published in 1876, he described his native dialect of Kerenz. By analyzing the activity of the organs producing language (dialect) sounds, he was the founder of the so-called sound physiology (together with his teacher Eduard Sievers). In his prestructural approach, he noticed that there are sounds with and others without the capacity to change meaning. Purely structural terms were used already, such as Lautgegensatze (‘contrasts of sound’), (Sprach-)Bau ‘(linguistic) structure,’ and Konsonantensystem, Sprachsystem ‘system of consonants, of language.’ There w…