Measuring Space-Time Geometry over the Ages

Theorists are often told to express things in the "observational plane". One can do this for space-time geometry, considering "visual" observations of matter in our universe by a single observer over time, with no assumptions about isometries, initial conditions, nor any particular relation between matter and geometry, such as Einstein's equations. Using observables as coordinates naturally leads to a parametrization of space-time geometry in terms of other observables, which in turn prescribes an observational program to measure the geometry. Under the assumption of vorticity-free matter flow we describe this observational program, which includes measurements of gravitational lensing, proper motion, and redshift drift. Only 15% of the curvature information can be extracted without long time baseline observations, and this increases to 35% with observations that will take decades. The rest would likely require centuries of observations. The formalism developed is exact, non-perturbative, and more general than the usual cosmological analysis.Comment: Originally written for the Gravity Research Foundation 2012 Awards for Essays on Gravitation and received Honorable Mentio

Symmetry and The Creative Cognition

An unconquered conceptual divide related to cognitive perception exists between the physical and biological sciences. The life processes of self assembly and replication are unaccounted for in quantum theory or in the ordinary laws of physics. Lying at the very base element of this confusion is a theoretical wall outlined by statistical generalization on one border, and exact historical evolution on the other. Can inert, randomly oriented, statistically described agents (atoms/molecules), direct the reproduction of like things. If the answer to this proposition is negative, then are space and matter not as assumed (i.e. – as uniformly interpretable statistical entities), but things with a life like evolving history from a unique beginning. For example: if life processes are conceptually tree like, can (must) the processes from which they are created be defined this way also? If one reflects on this question he can liken it to a similar question: can a tree exist with one branch only (i.e. can a tree exist as a simple line verses a line with an origin and history) a conflict emerges that reveals a subtler conflict in the pursuit of an objective interpretation. A simple line always is less complex than the other and does not exist in the life processes or even in the ordinary life of an individual: it's history, in terms of life time, is infinitely\ud smaller the closer it resembles a simple undefined line. In defining matter statistically, we are objectively claiming that it has no time dependant history, and yet is the objective source of evolution, which by definition has a subjective history. We are left with the alternative to find a new order for the definition of physical processes. In this paper, I wish to show that with very little rearrangement of current notions, a model of space can be created that details the replication, from an origin, and propagation in a tree like manner with a declining potential, of both the evolutionary processes of living things, and space, and matter

Paradigm Case Arguments

From time to time philosophers and scientists have made sensational, provocative claims that certain things do not exist or never happen that, in everyday life, we unquestioningly take for granted as existing or happening. These claims have included denying the existence of matter, space, time, the self, free will, and other sturdy and basic elements of our common-sense or naïve world-view. Around the middle of the twentieth century an argument was developed that can be used to challenge many such skeptical claims based on linguistic considerations, which came to be known as the Paradigm Case Argument ..

Does Physics Provide Us With Knowledge About the Things in Themselves ?

Kant said that we were never be able to know about the true nature of matter. The things in themselves would remain unknown to us. There is a similar problem in quantum mechanics. You cannot provide directly any property to a physical state represented by a ray in a Hilbert space. The general theory of relativity teaches time and space were not how they appear to us, but claims to know that in fact space and time would belong to a curved space-time. It turned out in the last decades that it is extraordinary difficulty to combine both theories. Based on quantum mechanics I argue in this paper that the things in themselves remain unknown. There is probably no substance which we can call space-time

Does Physics Provide Us With Knowledge About the Things in Themselves ?

Kant said that we were never be able to know about the true nature of matter. The things in themselves would remain unknown to us. There is a similar problem in quantum mechanics. You cannot provide directly any property to a physical state represented by a ray in a Hilbert space. The general theory of relativity teaches time and space were not how they appear to us, but claims to know that in fact space and time would belong to a curved space-time. It turned out in the last decades that it is extraordinary difficulty to combine both theories. Based on quantum mechanics I argue in this paper that the things in themselves remain unknown. There is probably no substance which we can call space-time

Relationalism about mechanics based on a minimalist ontology of matter

This paper elaborates on relationalism about space and time as motivated by a minimalist ontology of the physical world: there are only matter points that are individuated by the distance relations among them, with these relations changing. We assess two strategies to combine this ontology with physics, using classical mechanics as example: the Humean strategy adopts the standard, non-relationalist physical theories as they stand and interprets their formal apparatus as the means of bookkeeping of the change of the distance relations instead of committing us to additional elements of the ontology. The alternative theory strategy seeks to combine the relationalist ontology with a relationalist physical theory that reproduces the predictions of the standard theory in the domain where these are empirically tested. We show that, as things stand, this strategy cannot be accomplished without compromising a minimalist relationalist ontology

Kinds of Impenetrability

Faced with the conflict between our intuition that no two things ever share a place at a time and these counterexamples to it, philosophers usually try to find a happy medium between sticking with the original intuition and rejecting all of its counterexamples or giving up the whole intuition and accepting all the counterexamples. Some counterexamples might be rejected on conceptual grounds : one may deny for instance that absolute space is in the same place that the entities located therein on the ground that absolute space is not itself located. One may also reject the distinct existence of some of the entities put forward in the examples : determinable properties might be nothing else than boolean combinations of determinate ones, spots on a screen may be just four dimensional worms whose passing through each other is a matter of part sharing rather than compenetration, etc. But as long as the conceivability of at least one counterexample is granted, the impenetrability intuition has to be weake- ned. To this end, one can weaken either the modal force of the impenetrability intuition or its scope. One may claim for instance that things are impenetrable in our world, but grant that the remaining counterexample refers to genuine metaphysical possibilities (although not natural ones). On the other hand, on may claim that the impenetrability intuition does not bear on every entity in the outside world, but only on some of them. Locke, famously, did not want to give up the metaphysical necessity of impenetrability, but agreed to restrict it to entities of the same kind.4 One other way to restrict the scope of the intuition of impenetrability is to claim that only independent entities (substances, or things proper) are impenetrable , or that only material entities are