1,721,504 research outputs found
Why can hadronic stars convert into strange quark stars with larger radii
No full textThe total binding energy of compact stars is the sum of the gravitational binding energy (BE)g and the nuclear binding energy (BE)n, the last being related to the microphysics of the interactions. While the first is positive (binding) both for hadronic stars and for strange quark stars, the second is large and negative for hadronic stars (antibinding) and either small and negative (antibinding) or positive (binding) for strange quark stars. A hadronic star can convert into a strange quark star with a larger radius because the consequent reduction of (BE)g is overcompensated by the large increase in (BE)n. Thus, the total binding energy increases due to the conversion and the process is exothermic. Depending on the equations of state of hadronic matter and quark matter and on the baryonic mass of the star, the contrary is obviously also possible, namely, the conversion of hadronic stars into strange quark stars having smaller radii, a situation more often discussed in the literature. We provide a condition that is sufficient and in most of the phenomenologically relevant cases also necessary in order to form strange quark stars with larger radii while satisfying the exothermicity request. Finally, we compare the two schemes in which quark stars are produced (one having large quark stars and the other having small quark stars) among themselves and with the third-family scenario and we discuss how present and future data can discriminate among them
Atomism and the reasoning by a non-classical logic
No full textOften, in the original scientific writings, a double negated statement (DNS) is not equivalent to his corresponding positive one; that means the inferring law ¬¬A → A does not apply. Recent studies recognized in the failure of this logical law the borderline between classical and non-classical logics. Original writings by classical chemists dealing with the problem of atomism are particularly characterized by the occurrences of DNSs. An historical case, Avogadro's contribution to atomism (i.e. the well-known hypothesis about the constitution of gases), is here analyzed in such terms. It turns out that, in order to support his ideas, Avogadro suggested several ad absurdum proofs, indeed a way of reasoning typically linked to the use of DNSs. Copyright © 1999 by HYLE and Antonino Drago & Romina Oliva
Il dualismo discreto continuo nella storia delle teorie matematiche della guerra
No full textAtti del V congresso Nazionale di Storia della Fisica (a cura di S. D'Agostino, S. Petruccioli
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