Sharif Digital Repository

Decoherence is one of the candidates for solving the measurement problem, and is among the group of theories which are trying to solve the measurement problem within the quantum theory, by removing the wave function reduction axiom. The main idea is to consider the environment of the system which was ignored in the classical physics. The openness of a quantum systems makes the system and its environment entangled, and that leads to the transmission of system information to the environment, and finally, the system loses its individuality. This approach claims that since the observer can’t control and consider all the degrees of freedom of the environment and has only access to the system,... 

In recent decades, the idea of multiverse has been raised in several areas of physics for different reasons. One of the interpretations of quantum mechanics, the inflation theory in cosmology and string theory in fundamental physics have led to the multiverse idea. On the other hand, after the problem of fine-tuning of the constants of nature became a hot topic in recent decades, physicists have tried to find a way to explain this puzzle. One of the most important approaches that have been suggested by some physicists, as a scientific explanation for this problem, is the idea of multiverse and they are even willing to set aside the principle of observability to confirm physical... 

Quantum Mechanics, as the most famous physical theory was founded about 85 years ago; but still there are a lot of debates about its interpretation. In this work, we review some basic concepts of Quantum Mechanics in form of questions about uncertainty principle, measurement problem and complementarily. We also review Bell inequality which has great philosophical and recently technological results. Bell derived his inequality regardless of modeling the measuring apparatus; we show, by take a realistic model for measuring apparatus, Bell inequality would be deduced. Finally we review a mathematical language which was used to show the duality of wave and particle. Quantum... 

In this investigation has been tried to indagate the Bell’s inequality both theoretically and experimentally. This inequality published by John Bell in 1964 on the EPR argument. In the EPR argument they reasonably deduced that quantum mechanics with the wave function interpretation is incomplete (but proposing correct results), so we must looking for a deterministic and more fundamental and underlying theory than common quantum mechanics, the alternative theory shall contain Reality and Locality assumptions and also could produce current quantum mechanics results. Afterward, scientific probation started for finding a deterministic theory that including hidden variables, infact supplement... 

Investigation of the consistency between physical theories has always resulted in the advancement of physics. Meanwhile, study of the consistency between quantum mechanics and thermodynamics has led to the development of a branch in theoretical physics called quantum thermodynamics. In addition to the consistency problem,employing other features of quantum mechanics such as coherency and entanglement, to enhance thermodynamic processes is another ongoing subject of research. In order to study the thermodynamics of quantum systems, we use the first law of thermodynamics to present a derivation of quantum potential. Quantum potential is a term in the equations of motion of a quantum system of... 

Natural sciences have philosophical and ideological fundamentals. "The attitude towards human", is one of these philosophic or metaphysical fundamentals of science so that scientists and researchers, attentive or not, take it as a basis for their scientific activities. In the other hand, "the science" also affects "The attitude towards human", and different scientific theories caused various attitudes towards human to take shape. "Renaissance" is one of the most important and sophisticated historical periods of the west`s history, and the changes in this period are among the main basics of entering the modern age. In this thesis, first of all some issues about the fundamentals of the science... 

To answer the explanabilty of consciousness, we have first clarified the terms “consciousness”, “explanation”, and “physic”, concluding that consciousness and physics should be integrated in a single unified explanatory system. The common problem we have targeted in this work is “direct observation”. Then, inspired by Bergson, we have suggested that ,in direct observation, there is a unity between observer and the observed, out of which the qualitative characteristic of experience or qualia is constructed. Following computer graphic courses, this unity is called “rendering unity”. In the next scientific step, by analyzing the Wigner’s friend paradox, we have stipulated that, in direct... 

Paul Feyerabend, an Austrian philosopher of science, is known as one of major critics of science and philosophy of science in 20th century. This inquiry is an attempt to study and criticize the bedrock of Feyerabend's philosophy of science. In the first chapter there will be an intruduction to enter the subject. In the second chapter the method of this study will be explained. Third chapter is a reconstruction of Feyerabend's philosophy of science. In the 4th chapter bedrock of Feyerabend's philosophy of science is derived to be: scepticism and fighting against dogmatism, defying monopolization, humanistic concerns and his personal character. In the last chapter there will be criticisms on... 

The universe appears to be homogeneous and isotropic as far as we can detect, which is called the Cosmological Principle. Standard big-bang model was successful in describing the universe. For example, it predicts the Hubble’s law of expansion for the universe, existence of the Cosmological background radiation and the correct abundance for the light atomic nuclei. Nevertheless, this model was unable to explain some problems in cosmology, for example horizon problem, smoothness problem and flatness problem. In the early 1980s, Inflation Theory was proposed by Alun Guth and others to resolve these problems in Standard Cosmology; but in two recent decades some contemporary prominent... 

In this dissertation we study the derivation of the second law of thermodynamics from an underlying physics. After discussing different methods for this derivation, we conclude that the only way to fulfill this, is to use a probabilistic mechanics which has probability as an inherent concept in itself, not as a supplementary one like statistical mechanics. This mechanics in contrary to the Newtonian mechanics, should be indeterministic  

The Quantum nonlocality problem, which has been tested with the Bell experiment, is one of the problems that doesn't have any explanation. Some people believed that there is a conflict between Quantum nonlocality and Special Relativity, the reason why, is Special Relativity based on Lorentz Transformations that don't allow us exceeding from speed of light. But in the nonlocality problem we understand that data transmition is instantaneous (at least is faster than speed of light). So it seems that we must look for transformations in which there is a possibility for exceeding from speed of light, the Lorentz Transformations is the special case of them. Then we can explain nonlocality with... 

At least nine different formalisms have been presented for Quantum mechanics which by itself can indicate the incomplete understanding of Quantum theory. Each formalism has its own ups and downs, but de Broglie–Bohm approach which is based on representing a causal interpretation has a special place among them. This approach not only can explain the statistical approach to an ensemble of systems, but also can describe single systems. There are two general approaches in de Broglie–Bohm formalism. The first approach which includes more things in itself than the other approach is Bohm’s which considers Quantum potential energy as the principal factor in causing Quantum effects. The original idea... 

One of the important issues in the fundamental physics is the arrow of time. According to the fundamental theories, motion is symmetry with respect to the passage of time while on a macroscopic level time has direction. In the macroscopic models the arrow of time is provided by the Second Law of Thermodynamics.The thermodynamic arrow is often linked to the cosmological arrow of time, because it is ultimately about the boundary conditions of the early universe.Recently people have tried to suppose this challenge as a fundamental issue and use this as fundamental assumption in their theories.A number of models have attempted to solve the problem based on the concept of information.... 

General Relativity is a generally covariant and deterministic theory of space-time. The Hole Argument requires that there is no substantivalist interpretation of general relativistic space-time. In this thesis, I am intended to show that this conclusion is not compelling. Through this, a deeper understanding of philosophical and mathematical content of General Relativity is investigated  

The concept of symmetry has long been the focus of numerous debates in different fields; some have come up with an artistic approach looking for a beautiful notion germane to the concept of symmetry. Others have examined this issue from a philosophical viewpoint and studied the ontology of symmetry and philosophers like Kant moved beyond the limits and have given their symmetry a transcendental position. On the other hand, in an anti-realist position relying on the fact that the goal of science is not truth but merely it’s an empirical adequacy, Van Fraassen argued that “science was rapidly gaining autonomy not only from theology but from all of philosophy, and was exploiting concepts and... 

In this thesis a brief review of the concept of vacuum has been studied. In addition, we shall see how we can determine the vacuum energy in a flat space-time. Also the renormalization and the regularization of zero point energy, which is 122 order of magnitude more than the critical density energy, has been represented. Then, we study supersymmetry which is a candidate to solve this problem. Furthermore, different ways to determine cosmological constant and the orbits of planets has been studied.Finally, by studying free fall experiments, the gravitational properties of vacuum has been represented.Caisimir effect, one of the most amazing predictions in the history of physics, and Lamb... 

The problem of science-religion relation is considered here, considering realism and the cognitive status of religious statements and accepting the existence of common issues between science and religion. Different approaches have been adopted to explain this relation. One of the approaches which have been proposed in recent years has been the issue of religious science, which is considered to solve incompatible issues between science and religion. The possibility of religious science is one of the important problems that have attracted the mind of some Muslim scholars and some devoted Muslims. Some motivation could be mentioned for bringing in this issue, like the removal of conflict... 

Quantum mechanics is very succesful in the description and prediction of the microphysical world. So nowadays very few doubt its authenticity. Nevertheless, there are some conceptual issues that are still under debate, such as action at a distance. It took a while after the introduction of the EPR paradox in 1935 until John Stewart Bell derived an inequality, using local hidden variables. This inequality was in contrast with predictions of quantum mechanics. Experiments also contradicted this inequality. This implies that there is action at distance which, in turn suggests, the violation of the special relativity. In this thesis, we consider this issue and shall see that on the one hand we... 

The worldview and value system can use a cognitive-normative framework to select and shape science and technology. Of course, this framework is not the sole factor in shaping and selecting science and technology. The context in which science and technology flourish is also an important factor. Thus a religious science and technology is possible. Furthermore one can find many examples in the contemporary science and technology which are rooted in a secular and naturalistic outlook., but one can shape a science and technology which are rooted in religious worldview and value system. These examples show that one can generate a religious type of science and technology ,but in order to do this... 

Earlier in the philosophical tradition, the realists’ view that world exist in itself, independently of our knowledge, had been challenged by idealists, who denied such existence and considered the world and its objects as a function of (our) perception. Today, some philosophers have challenged the (scientific) realists’ belief in the existence of scientific unobservable entities, such as electrons, quarks, forces, gravitational fields, cells, bacteria, genes and so on, that are posited by the modern scientific theories. The debates which have been made in this regard, in recent decades, have spurred an important controversy known as “scientific realism and antirealism debate” in the field...