scholarly journals Understanding the Interstellar Medium

2007 ◽  
Vol 6 (2) ◽  
pp. 45-56
Author(s):  
Nagalakshmi A. Rao
Keyword(s):  
Interstellar Medium ◽  
Spectral Absorption ◽  
Evolution Of The Universe ◽  
Potential Activity ◽  
The Universe ◽  
Absorption Features

The Interstellar Medium- the medium between the stars is an active and dynamic medium and is a region of potential activity. Probing the ISM is interesting in itself. Understanding the gas and grains of the ISM provides vital clues on the evolution of the universe and our galaxy. The birth and death of stars takes place in the ISM. Spectral absorption features provide a wealth of information on the nature and composition of grains.

scholarly journals 34. Interstellar Matter

1985 ◽  
Vol 19 (1) ◽  
pp. 437-478
Author(s):  
M. Peimbert ◽  
J. Lequeux ◽  
S. D’Odorico ◽  
B. G. Elmegreen ◽  
E. B. Kostyakova ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Present State ◽  
Theoretical Models ◽  
Interstellar Matter ◽  
Evolution Of The Universe ◽  
Formation And Evolution ◽  
The Subject ◽  
Astronomical Research ◽  
Theories Of Evolution ◽  
The Universe

It has become more evident during the last three years that the study of interstellar matter is paramount to understand the evolution of the universe and its constituents. From observations of the present state of the interstellar medium, in our galaxy, in other galaxies, and between galaxies, it is possible to test theories of: evolution of the universe, formation and evolution of galaxies, formation and evolution of stars and of the evolution of the interstellar medium itself. The amount of information on the interstellar medium that has been gathered during the 1982-1984 period has been very large and the theoretical models that have been ellaborated to explain these observations have been very numerous, these facts show that the subject of our Commission constitutes a very active field of astronomical research.

scholarly journals Statistical study of the ISM of GRB hosts

2012 ◽  
Vol 10 (H16) ◽  
pp. 620-620
Author(s):  
A. de Ugarte Postigo ◽  
J. P. U. Fynbo ◽  
C. C. Thöne ◽  
L. Christensen ◽  
J. Gorosabel ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Statistical Study ◽  
Gamma Ray ◽  
Host Galaxies ◽  
Different Types ◽  
Luminous Objects ◽  
The Universe ◽  
Absorption Features ◽  
Current Record ◽  
Law Making

AbstractGamma-ray burst (GRB) afterglows shine, during a brief period of time as the most luminous objects that can be detected in the Universe. They have been observed at almost any redshift, from our nearby environment (the nearest one, at z = 0.08) to the very distant Universe (the current record holder at z = 9.4). Their optical spectra are well reproduced by a clean, simple power law, making them ideal light houses to probe the interstellar medium of their host galaxies at any redshift. We have used the largest sample of GRB afterglow spectra collected to date to perform a statistical study of the interstellar medium in their host galaxies. By analysing the distribution of equivalent widths of the most prominent absorption features we evaluate the different types of environments that host GRBs and study their diversity.

PHILOSOPHY AND THE MEANING OF LIFE

Think ◽  
2021 ◽  
Vol 21 (60) ◽  
pp. 33-49
Author(s):  
William Lyons
Keyword(s):  
Human Life ◽  
Meaning Of Life ◽  
Point Of View ◽  
Eternal Life ◽  
Evolution Of The Universe ◽  
Life On Earth ◽  
The Universe

The author sets out to respond to the student complaint that ‘Philosophy did not answer “the big questions”’, in particular the question ‘What is the meaning of life?’ The response first outlines and evaluates the most common religious answer, that human life is given a meaning by God who created us and informs us that this life is just the pilgrim way to the next eternal life in heaven. He then discusses the response that, from the point of view of post-Darwinian science and the evolution of the universe and all that is in it, human life on Earth must be afforded no more meaning than the meaning we would give to a microscopic planaria or to some creature on another planet in a distant universe. All things including human creatures on Planet Earth just exist for a time and that is that. There is no plan or purpose. In the last sections the author outlines the view that it is we humans ourselves who give meaning to our lives by our choices of values or things that are worth pursuing and through our resulting sense of achievement or the opposite. Nevertheless the question ‘What is the meaning of life?’ can mean quite different things in different contexts, and so merit different if related answers. From one point of view one answer may lie in terms of the love of one human for another.

Evolution of the universe from the perspective of entropy and information

2021 ◽  
pp. 2150111
Author(s):  
Fei-Quan Tu ◽  
Bin Sun ◽  
Meng Wan ◽  
Qi-Hong Huang
Keyword(s):  
Information Entropy ◽  
Second Law Of Thermodynamics ◽  
Boltzmann Entropy ◽  
Evolution Of The Universe ◽  
Thermodynamic Entropy ◽  
Entire Universe ◽  
Low Entropy ◽  
The Relationship ◽  
The Universe ◽  
Entropy Of The Universe

Entropy is a key concept widely used in physics and other fields. At the same time, the meaning of entropy with different names and the relationship among them are confusing. In this paper, we discuss the relationship among the Clausius entropy, Boltzmann entropy and information entropy and further show that the three kinds of entropy are equivalent to each other to some extent. Moreover, we point out that the evolution of the universe is a process of entropy increment and life originates from the original low entropy of the universe. Finally, we discuss the evolution of the entire universe composed of the cosmological horizon and the space surrounded by it and interpret the entropy as a measure of information of all microstates corresponding to a certain macrostate. Under this explanation, the thermodynamic entropy and information entropy are unified and we can conclude that the sum of the entropy of horizon and the entropy of matter in the space surrounded by the horizon does not decrease with time if the second law of thermodynamics holds for the entire universe.

scholarly journals From Quantum Unstable Systems to the Decaying Dark Energy: Cosmological Implications

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Aleksander Stachowski ◽  
Marek Szydłowski ◽  
Krzysztof Urbanowski
Keyword(s):  
Dark Energy ◽  
Time Reversal ◽  
Hubble Parameter ◽  
Decay Process ◽  
Time Dependent ◽  
Time Reversal Symmetry ◽  
Exponential Form ◽  
Cosmological Time ◽  
Evolution Of The Universe ◽  
The Universe

We consider a cosmology with decaying metastable dark energy and assume that a decay process of this metastable dark energy is a quantum decay process. Such an assumption implies among others that the evolution of the Universe is irreversible and violates the time reversal symmetry. We show that if we replace the cosmological time t appearing in the equation describing the evolution of the Universe by the Hubble cosmological scale time, then we obtain time dependent Λ(t) in the form of the series of even powers of the Hubble parameter H: Λ(t)=Λ(H). Our special attention is focused on radioactive-like exponential form of the decay process of the dark energy and on the consequences of this type decay.

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