Momentum-Transfer to and Elementary-Excitations of a Bose-Einstein Condensate by a Time-Dependent Optical Potential

We present results of calculations on Bose-Einstein condensed $^{87}$Rb atoms subjected to a moving standing-wave light-potential of the form $V_L(z,t) = V_0(t) \cos(q z-\omega t)$. We calculate the mean-field dynamics (the order paramter) of the condensate and determine the resulting condensate momentum in the $z$ direction, $P_z(q,\omega,V_0,t_p)$, where $V_0$ is the peak optical potential strength and $t_p$ is the pulse duration. Although the local density approximation for the Bogoliubov excitation spectral distribution is a good approximation for very low optical intensities, long pulse duration and sufficiently large values of the wavevector $q$ of the light-potential, for small $q$, short duration pulses, or for not-so-low intensities, the local density perturbative description of the excitation spectrum breaks down badly, as shown by our results.Comment: 8 pages, 7 figure

Once women embrace stem, there’s no going back to the old culture of ‘pink-collar’ jobs

The influx of women from the former Soviet Union, with their strong science and engineering culture, altered gender norms in Israel, write Naomi Friedman-Sokuler and Claudia Seni

Kantian Motives in Work of Ludwig Wittgenstein

It is proved that the basic framework of the premises and reasoning of Wittgenstein's “Tractatus Logico-philosophicus” corresponds quite well to the transcendental method (as formulated by H. Cohen). Whereas Kant’s philosophy proceeds from the fact of existence of mathematics and mathematised natural science and investigates their conditions of possibility, Wittgenstein proceeds from the fact that propositions of language describe reality and reveals the conditions of possibility of such descriptions. Kant, answering the question about the conditions of possibility of the named sciences, comes to the idea of the transcendental subject and the distinction between the world of phenomena and the thing in itself. Wittgenstein's investigation of the conditions of possibility that the world is described by propositions leads to the assertion that both the world and language are together in logical space. The latter constitutes the a priori and transcendental condition of the possibility that language “reaches out” to reality. For both the theories - in the “Critique of Pure Reason” and in the “Tractatus Logico-Philosophicus” - the idea of the boundary is important. In the “Critique of Pure Reason” it is the boundary of possible experience and cognition, while in the “Tractatus Logico-Philosophicus” it is the boundary of what can be thought and expressed by meaningful propositions. Related to the different definitions of the boundary is the difference in the treatment of mathematised natural science. For “The Critique of Pure Reason” was created in the era of unconditional acceptance of Newtonian mechanics. And the “Tractatus Logico-Philosophicus” was created at the time of the crisis of the Newtonian paradigm and its replacement by other notions of time and space. However, the idea of boundary, which is present in both doctrines, determines closeness in the attitude towards metaphysics between the author of “The Critique of Pure Reason” and the author of “The Tractatus Logico-Philosophicus”. The study also shows that Wittgenstein did not follow logicism in his philosophy of mathematics. For him, both mathematical objects and propositions of logic are constructions. The conviction about the constructive character of mathematical and logical objects shows an affinity with the Kantian tradition in the philosophy of mathematics

Praise be to the plague?

Among the various human attitudes toward a pandemic, along with fear, despair and anger, there is also an urge to praise the catastrophe or imbue it with some sort of hope. In 2020 such hopes were voiced in the stream of all the other COVID-19 reactions and interpretations in the form of predictions of imminent social, political or economic changes that may or must be brought on by the pandemic, or as calls to “rise above” the common human sentiment and see the pandemic as some sort of cruel-but-necessary bitter pill to cure human depravity or social disorganization. Is it really possible for a plague of any kind to be considered a relief ? Or perhaps a just punishment? In order to assess the validity of such interpretations, this paper considers the artistic reactions to the pandemics of the past, specifically the images of the plague from Alexander Pushkin’s play Feast During the Plague, Antonin Artaud’s essay “The Theatre and the Plague” and Albert Camus’s novel The Plague. These works in different ways explore an attitude in which a plague can be praised in some respect. The plague can be a means of self-overcoming and purification for both an individual and for society. At the same time, Pushkin and Camus, each in his own way and by different means, show the illusory nature of that attitude. A mass catastrophe can reveal the resources already present in humankind, but it does not help either the individual or the society to progress

The Concept of Virtue in Religious Philosophy of Hermann Cohen

The concept of virtue was of great interest and importance for H. Cohen. In the interpretation of this concept in his latest work “Religion of reason from the sources of Judaism” the most important concepts of this work were brought in the focus: the specificity of definition of what is the religion of reason; understanding of the uniqueness of God; correlation; messianism. For Cohen, a single system of virtues presupposes a single and unique ethics and correlates with the idea of the unity of humanity. The last concept, in his opinion, maturated in the fold of monotheism. Humanity is one, because all people are creations of the unique God. “Religion of reason” treats of the common universal virtues. In the religion of reason, the idea of God and morality are inextricably linked. Cohen rejects metaphysical speculation about the nature of God, about the attributes of God inherent in himself. The religion of the mind speaks of God only in correlation with man. God is a moral ideal and reveals himself to man by giving him moral commandments. Morality connects man and God, and this connection is revealed in detail by Cohen in the theme of virtues. Understanding God as Truth is important for the disclosure of this topic. The corresponding virtue for a person is faithfulness to truth, or truthfulness. In addition to truthfulness in the usual sense, for Cohen, faithfulness to truth requires correct worship of God. The correlation culminates in the idea of messianism, which is interpreted by Cohen as an endless movement of a whole humanity to the social justice.</jats:p

Hermann Cohen and His Idea of the Logic of Pure Knowledge

Hermann Cohen, as it is well known, criticised the Kantian notion of the thing-in-itself. And before him the Kantian thing-in-itself was criticised by Fichte and other German idealists. Probably for this reason, Hermann Cohen is sometimes regarded as a person who said things similar to Fichte. This gives a completely wrong perspective, making it impossible to understand the philosopher's ideas. The basis for his critique of the Kantian thing-in-itself is quite different from the motives, determining the criticism of Kant in the classical German Idealism. Such interpretation does not allow to see close connection of Cohen's theoretical philosophy with revolution in physics which took place at the turn of the nineteenth and twentieth centuries. The article explains how Cohen's demand that pure thinking must form its own content is connected with transformations taking place in physics and mathematics, and the peculiarity of Cohen's understanding of idealism is demonstrated: for him, correct idealism must realize that autonomous, free thinking should work seriously with sense data. The closeness of Cohen's ideas to the postpositivist thesis of the theory-ladenness of observation is explained. For Cohen, serious work with sense data is opposite to uncritical acceptance of them as given. The origin of scientific thinking is thinking itself. It responds to the challenge of sensory material by creating its own constructs. Mathematized natural science becomes for Cohen both an example and a confirmation of this thesis. For him, what is real is what is described in the language of mathematical analysis, i.e. continuous processes, in spite of the fact that any data are discrete. It is shown that the source of Cohen's assertions on this issue is in Kant's Critique of Pure Reason, namely in the doctrine of the Principles of pure natural science and, more specifically, in the Anticipations of Perception. Cohen's conviction of the constructive character of the theories of mathematized natural science is confirmed in the article by references to the authority of A. Einstein.</jats:p

Cohen Hermann

The article presents a sketch of the biography and work of Hermann Cohen, head of the Marburg School of Neo-Kantianism. It shows how wrong it is to think that Cohen reduced all philosophy to a theory of knowledge. At the same time, the theory of knowledge really occupied an important place in Cohen's system, and by knowledge he meant first of all mathematized natural science, although he paid attention to the notion of goal and its importance both for biology and philosophical system, contributing to unification of the doctrine of knowledge and ethics. A peculiarity of Cohen's understanding of idealism is shown: the latter becomes fruitful only when it does not lose sight of that which is distinct from reason, constitutes a difficulty for it, and thus sets a task for it, namely sensual data. It is analyzed how Cohen saw such idealism in Plato and Kant, as well as in the scientific revolution of the late 19th and early 20th centuries, in particular in the crisis of mechanistic understanding of matter and in A. Einstein's theory of relativity. The origins of Cohen's understanding of continuity, reality and their connection, as well as his understanding of the thing-in- itself are considered. Attention is drawn to the connection between Cohen's understanding of the infinite task of knowledge (approximation to the thing-in-itself) and his idea of humanity. The development of this idea in Cohen's ethics and aesthetics is presented. Transcendental freedom (as a thing-in-itself in general), from his point of view, cannot be a given distinctive feature of the subject, but remains an infinite task facing humanity as a whole. More details is given on Cohen's philosophy of religion, which became the final part of his system. Cohen defines his own notion of the religion of reason and explains its distinction from ethics. Religion of reason recognizes the irreducible self of the Other, repentance, redemption, and renewal. Although the religion of reason belongs to all humanity, it first begins to form and develop in Judaism. The Cohenian understanding of God, the religion of reason as ethical monotheism and the idea of the correlation between God and man are analyzed. It is shown that ethical monotheism in Cohen's understanding culminates in the idea of messianism.</jats:p