Science – Page 7 – Dictionaries

Causal Loops in Time Travel

About the possibility of time traveling based on several specialized works, including those of Nicholas J. J. Smith (“Time Travel“), William Grey (”Troubles with Time Travel”), Ulrich Meyer (”Explaining causal loops”), Simon Keller and Michael Nelson (”Presentists should believe in time-travel”), Frank Arntzenius and Tim Maudlin (“Time Travel and Modern Physics“), and David Lewis (“The Paradoxes of Time Travel”). The article begins with an Introduction in which I make a short presentation of the time travel, and continues with a History of the concept of time travel, main physical aspects of time travel, including backward time travel in the past in general relativity and quantum physics, and time travel in the future, then a presentation of the Grandfather paradox that is approached in almost all specialized works, followed by a section dedicated to the Philosophy of time travel, and a section in which I analyze Causal loops for time travel. I finish my work with Conclusions, in which I sustain my personal opinions on the time travel, and the Bibliography on which the work is based.

Keywords: time travel, grandfather paradox, causal loops, temporal paradoxes, causality

CONTENTS

Abstract
Introduction
History of the concept of time travel
Grandfather paradox
The philosophy of time travel
Causal loops
Conclusions
Bibliography
Notes

DOI: 10.13140/RG.2.2.17802.31680

MultiMedia Publishing: https://www.telework.ro/en/e-books/causal-loops-in-time-travel/

Causal Loops in Time Travel

The new (liberal) eugenics

Despite the Nazi horrors, in 1953 the new eugenics was founded, when Watson and Crick postulated the double helix of DNA as the basis of chemical heredity. In 1961, scientists have deciphered the genetic code of DNA, laying the groundwork for code manipulation and the potential building of new life forms. After thirty years from the discovery of the DNA structure, the experimenters began to carry out the first clinical studies of human somatic cell therapy.
The practice of prenatal genetic tests identifies genes or unwanted genetic markers. Parents can choose to continue pregnancy or give up the fetus. Once the preimplantation genetic diagnosis occurs, potential parents can choose to use in vitro fertilization and then test early embryonic cells to identify embryos with genes they prefer or avoid. Because of concerns about eugenics, genetic counseling is based on a “non-directive” policy to ensure respect for reproductive autonomy. The argument for this counseling service is that we should balance parental autonomy with child’s autonomy in the future. Specialists have not yet given a clear answer to the question of whether these practices should be considered eugenic practices, or if they are moral practices.
DOI: 10.13140/RG.2.2.28777.95849

The new (liberal) eugenics

Newton’s Principia on God-mediated action

As John Henry states, Newton simply wants to reaffirm the truth of God’s omnipresence without directly involving him in the physics of the world system. Newton simply wants to distance himself from a Cartesian concept of God and convince the atheists that God is a real presence extended in the world. God must exist in space for the space to exist, but God does not only act through contact. Henry believes that Andrew Janiak and Hylarie Kochiras give us a wrong picture of a Newton who believes in opportunism. Newton, Henry asserts, has always assumed that God acted through secondary causes:
DOI: 10.13140/RG.2.2.35495.39846

Newton’s Principia on God-mediated action

The Ontology of General Relativity

General Relativity generated various early philosophical interpretations. His adherents have highlighted the “relativization of inertia” and the concept of simultaneity, Kantians and Neo-Kantians have underlined the approach of certain synthetic “intellectual forms” (especially the principle of general covariance, and logical empirics have emphasized the philosophical methodological significance of the theory.
Reichenbach approached the GR through the “relativity of geometry” thesis, trying to build a “constructive axiomatization” of relativity based on “elementary matters of fact” (Elementartatbestande) for the observable behavior of light rays, rods and clocks.
The mathematician Hermann Weyl attempted a reconstruction of Einstein’s theory based on the epistemology of a “pure infinitesimal geometry”, an extended geometry with additional terms that formally identified with the potential of the electromagnetic field.
DOI: 10.13140/RG.2.2.11641.93281

The Ontology of General Relativity

Space, time, and time travel

Newton supported the idea of absolute time, unlike Leibniz, for which time is only a relation between events and cannot be expressed independently, a statement in concordance with the relativity of space-time.

Eternalism claims that the past and the future exist in a real sense, going to the idea that time is a dimension similar to spatial dimensions, that future and past events are “present” on the axis of time, but this view is challenged. On four-dimensional vision, the universe is an existing space-time topology, containing everything that has happened, everything that happens and everything that’s going to happen. It follows that there is no singular moment to be considered as insignificant as present. Time travel is possible if the four-dimensional vision including the time is correct, but it is not possible if presentism is true. William Godfrey-Smith says that “the metaphysical image underlying the discussion of time travel is that of the universe block, in which the world is conceived as extended in time as it is in space.”

DOI: 10.13140/RG.2.2.18575.64163

Space, time, and time travel

Science and pseudoscience – Falsifiability

The delimitation between science and pseudoscience is part of the more general task of determining which beliefs are epistemologically justified. Standards for demarcation may vary by domain, but several basic principles are universally accepted.
Karl Popper proposed falsifiability as an important criterion in distinguishing between science and pseudoscience. He argues that verification and confirmation can play no role in formulating a satisfactory criterion of demarcation. Instead, it proposes that scientific theories be distinguished from non-scientific theories by testable claims that future observations might reveal to be false.
DOI: 10.13140/RG.2.2.29821.61926

Science and pseudoscience – Falsifiability

Grandfather paradox in time travel

The most well-known example of the impossibility of traveling in time is the grandfather paradox or self-infanticide argument: a person who travels in the past and kills his own grandfather, thus preventing the existence of one of his parents and thus his own existence. A philosophical response to this paradox would be the impossibility of changing the past, like Novikov self-consistency principle (if an event exists that would cause a paradox or any “change” to the past whatsoever, then the probability of that event is zero, thus it would be impossible to create time paradoxes).
DOI: 10.13140/RG.2.2.31279.79521

Grandfather paradox in time travel

Karl Popper’s demarcation problem

Karl Popper, as a critical rationalist, was an opponent of all forms of skepticism, conventionalism and relativism in science. A major argument of Popper is Hume’s critique of induction, arguing that induction should never be used in science. But he disagrees with the skepticism associated with Hume, nor with the support of Bacon and Newton’s pure “observation” as a starting point in the formation of theories, as there are no pure observations that do not imply certain theories. Instead, Popper proposes falsifiability as a method of scientific investigation.

DOI: 10.13140/RG.2.2.11481.36967

Karl Popper’s demarcation problem

Classical theory of singularities

The singularities from the general relativity resulting by solving Einstein’s equations were and still are the subject of many scientific debates: Are there singularities in spacetime, or not? Big Bang was an initial singularity? If singularities exist, what is their ontology? Is the general theory of relativity a theory that has shown its limits in this case?
DOI: 10.13140/RG.2.2.22006.45124

Classical theory of singularities

Hooke’s claim on the law of gravity

Based on Galileo’s experiments, Newton develops the theory of gravity in his first book Philosophiæ Naturalis Principia Mathematica (“Principia“) of 1686. Immediately after, Robert Hooke accused Newton of plagiarism, claiming that he unduly assumed his “notion” of “the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the Center”. But, according to Edmond Halley, Hooke agreed that “the demonstration of the curves generated by it” belongs entirely to Newton.

DOI: 10.13140/RG.2.2.16867.81441

Hooke’s claim on the law of gravity