346 research outputs found
Stefan Roski, Bolzano’s Conception of Grounding
I review Stefan Roski's "Bolzano's Conception of Grounding"
Baryon number conservation in Bose-Einstein condensate black holes
Primordial black holes are studied in the Bose-Einstein condensate
description of space-time. The question of baryon-number conservation is
investigated with emphasis on possible formation of bound states of the
system's remaining captured baryons. This leads to distinct predictions for
both the formation time, which for the naively natural assumptions is shown to
lie between 10^{-12}\.\srm to 10^{12}\.\srm after Big Bang, as well as for
the remnant's mass, yielding approximately in the
same scheme. The consequences for astrophysically formed black holes are also
considered.Comment: 5 pages, no figure
On Ellipsoidal Collapse and Primordial Black-Hole Formation
We reinvestigate gravitational ellipsoidal collapse with special focus on its
impact on primordial black-hole formation. For a generic model we demonstrate
that the abundance and energy density of the produced primordial black holes
will be significantly decreased when the non-sphericity of the overdensities is
taken into account.Comment: 4 pages, 1 figure; v2: minor changes; report number added; v3:
references adde
Essentiality without Necessity
It is widely accepted that if a property is essential then it is
necessary. Against this I present numerous counterexamples
from biology and chemistry, which fall into two groups: (I) A
property is essential to a genus or species, yet some instances of
this genus or species do not have this essential property. (II) A
property is essential to a genus, yet some species of this genus
do not have this essential property. I discuss and reject four
minor objections. Then I discuss in depth whether a distinction
between constitutive essence and consequential essence is able to
handle these counterexamples. I conclude that this distinction
is better put as one between (1) the essence, which is necessary,
and (2) the essential properties, which are not formally necessary.
An essence of an object X is the substantial universal expressed
by its real definition. An object X has a property P essentially
iff the property P is explanatory and non-trivial, and P follows
from the essence of X
The Formal Cause in the Posterior Analytics
I argue that Aristotle’s account of scientific demonstrations in the Posterior Analytics is centred upon formal causation, understood as a demonstration in terms of essence (and as innocent of the distinction between form and matter). While Aristotle says that all four causes can be signified by the middle term in a demonstrative syllogism, and he discusses at some length efficient causation, much of Aristotle’s discussion is foremost concerned with the formal cause. Further, I show that Aristotle had very detailed procedures for identifying the formal cause, and that he is aware of several problems which might lead one to erroneously identify the wrong form as the cause of a property. Finally, I show that Aristotle’s account can easily be adapted to material causation, and through some modifications (introduction of process universals related through parthood), hinted at in II 11-12 and 16-17, to efficient and final causation
Michael T. Ferejohn, Formal Causes: Definition, Explanation, and Primacy in: Socratic and Aristotelian Thought
I review Michael T. Ferejohn's "Formal Causes: Definition, Explanation, and Primacy in Socratic and Aristotelian Thought
Sandra Lapointe (ed.) Themes from Ontology, Mind, and Logic: Present and Past – Essays in Honour of Peter Simons
I review Sandra Lapointe (ed.) "Themes from Ontology, Mind, and Logic: Present and Past – Essays in Honour of Peter Simons"
Corpuscular Consideration of Eternal Inflation
We review the paradigm of eternal inflation in the light of the recently
proposed corpuscular picture of space-time. Comparing the strength of the
average fluctuation of the field up its potential with that of quantum
depletion, we show that the latter can be dominant. We then study the full
respective distributions in order to show that the fraction of the space-time
which has an increasing potential is always below the eternal-inflation
threshold. We prove that for monomial potentials eternal inflaton is excluded.
This is likely to hold for other models as well.Comment: 10 pages, 2 figures; revised version to match submitted versio
- …
