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Francis Villatoro

@emulenews

27 Jul

@GastonGiribet

#arXiv Emergent Cosmology from Matrix Theory arxiv.org/abs/2107.11512 Matrix theory is a proposed non-perturbative definition of superstring theory in which space is emergent. It leads to a non-singular cosmology solving the horizon problem of Standard Big Bang. cc @GastonGiribet

"The new scenario does not involve a period of inflationary expansion. Since it is based on a nonperturbative approach to superstring theory, the scenario is free from any swampland constraints, consistency conditions which rule out many inflationary models."

"There are other approaches to obtaining space-time and cosmology from matrix theory. The new work is different in that space-time is obtained directly from the matrix theory."

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Francis Villatoro

@emulenews

27 Jul

#arXiv Three Impossible Theories, by Leonard Susskind arxiv.org/abs/2107.11688 "Black hole central dogma: as seen from the outside, a black hole can be described in terms of a quantum system with Area/(4 G) degrees of freedom, which evolves unitarily under time evolution."

"Analogously, cosmological central dogma: as seen from a causal patch a cosmological space-time can be described in terms of an isolated quantum system with Area/(4 G) degrees of freedom, which evolves unitarily under time evolution."

"Area refers to the area of the cosmological horizon (for de Sitter space metric Area = 4πR²). Hence, the second law of thermodynamics must be respected by all observations within a causal patch. Naively the second law means the entropy never decreases."

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Francis Villatoro

@emulenews

27 Jul

Kepler’s Battle With Mars: "Brahe’s data, obtained with the naked eye, were indeed accurate: to 1/30th the angular size of the Moon. Tycho Brahe’s data were so precise, it quickly became clear that neither the Ptolemaic nor the Copernican systems fit the data well."

"However, although the Copernican system was the less precise model, Kepler, accepted the heliocentric hypothesis. He first used the observations of Mars to obtain the orbit of Earth. Then, he mapped the Martian data from the geocentric frame to a heliocentric frame with ..."

"...the Sun displaced from the center of the orbit of Mars, which he took to be circular. The model worked much better than both the Ptolemaic and Copernican systems, but discrepancies remained. However, Kepler concluded that a different curve would work much better."

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Francis Villatoro

@emulenews

26 Jul

@pcoffeebreak

#NatureNews NASA investigates renaming James Webb telescope after anti-LGBT+ claims nature.com/articles/d4158… cc @pcoffeebreak James Webb, head of NASA from 1961 to 1968, was involved in persecuting gay and lesbian people during his career in government.

"Four astronomers, Lucianne Walkowicz, Chanda Prescod-Weinstein, Brian Nord and Sarah Tuttle, lead the renaming petition. They say that Webb passed a set of memos discussing “the problem of homosexuals and sex perverts” to a senator who was leading the persecution."

"David Johnson, a historian, says there is no evidence that Webb led or instigated persecution. Webb did attend a White House meeting on the threat allegedly posed by gay people, but the context of the meeting was to contain the hysteria that members of Congress were stirring up"

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Francis Villatoro

@emulenews

24 Apr

#Vacunas Impacto de las variantes genéticas de la espícula en las vacunas frente al SARS-CoV-2, por Jordi Reina y Pablo Fraile-Ribot (UIB) ncbi.nlm.nih.gov/pmc/articles/P… "Las compañías farmacéuticas están elaborando vacunas tanto de ARNm como vectoriales contra las nuevas variantes".

"Sin embargo, si en el futuro es preciso revacunar a la población con vacunas actualizadas, deberemos estudiar la posible implicación del “pecado antigénico original”, ya descrito en la gripe, y que determina que en una nueva vacunación con cepas antigénicamente distintas, ..."

"... el sistema inmune responde básicamente con los anticuerpos ya presentes y en menor medida con los nuevos inducidos por la nueva vacuna, disminuyendo la eficacia de esta segunda vacuna distinta".

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Francis Villatoro

@emulenews

16 Apr

#arXiv Stellarators as a Fast Path to Fusion arxiv.org/abs/2104.04621 Seventeen years after the beginning of the fusion program, sentiments changed in 1968 when tokamaks were shown to have confinement properties far beyond those of any other fusion concept.

Nonetheless, the absence of robust stability was concerning since that had been known from early tokamak experiments. An invention is required for a tokamak to have sufficient passive stability for a power plant.

Is the stellarator the required invention that makes the least change in the fundamental concept? Stellarators are intrinsically strongly non-axisymmetric, which means careful design is required for adequate confinement; the power plant construction requires roughly five years.

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