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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

The Baby Universe is Fine and the CFT Knows It: On Holography for Closed Universes

Big bang/big crunch closed universes can be realized in AdS/CFT, even though they lack asymptotically AdS boundaries. With enough bulk entanglement, the bulk Hilbert space of a closed universe can be holographically encoded in the CFT. We clarify the relation of this encoding to observer-clone proposals and refute recent arguments about the breakdown of semiclassical physics in such spaces. In the limit of no bulk entanglement, the holographic encoding breaks down. The oft-cited one-dimensional nature of the closed universe Hilbert space represents the limitation of the external (CFT) Hilbert space to access the quantum information in the closed universe, similar to the limitations imposed on observers outside a perfectly isolated quantum lab. We advocate that the CFT nevertheless continues to determine the physical properties of the closed universe in this regime, showing how to interpret this relationship in terms of a final state projection in the closed universe. We provide a dictionary between the final state wavefunction and CFT data. We propose a model of the emergence of an arrow of time in the universe with a given initial or final state projection. Finally, we show that the conventional EFT in the closed universe, without any projection, can be recovered as a maximally ignorant description of the final state. This conventional EFT is encoded in CFT data, and it can be probed by computing coarse-grained observables. We provide an example of one such observable. Taken together, these results amount to a clean bill of health for baby universes born of AdS/CFT.

FOS: Physical sciences↗
NASA NTRS1970

The ASEE-University of Maryland-Catholic University-NASA summer Faculty Fellowship Program

University faculty members go to Goddard for a period, often weeks, during which they engage actively in research and at the same time participate in seminars related to their research. The objectives of this program are: (1) stimulation of schools to become interested in the research problems confronting Goddard; (2) creation of interest of the university faculty to continue their research after completing the formal program; (3) stimulation of people through associations with the university faculty and through participation in the program's seminars; and (4) establishment of closer ties with the universities.

Morakis, J. C.↗
NASA NTRS1978

Survey of university programs in remote sensing funded under grants from the NASA University-Space Applications program

NASA's Office of Space and Terrestrial Applications (OSTA) is currently assessing approaches to transferring NASA technology to both the public and private sectors. As part of this assessment, NASA is evaluating the effectiveness of an ongoing program in remote sensing technology transfer conducted by 20 university contractors/grantees, each supported totally or partially by NASA funds. The University-Space Applications program has as its objective the demonstration of practical benefits from the use of remote sensing technology to a broad spectrum of new users, principally in state and local governments. To evaluate the University-Space Applications program, NASA has a near-term requirement for data on each university effort including total funding, funding sources, length of program, program description, and effectiveness measures.

Madigan, J. A.↗
NASA NTRS1984

Overview of the NASA/RECON educational, research, and development activities of the Computer Science Departments of the University of Southwestern Louisiana and Southern University

This document presents a brief overview of the scope of activities undertaken by the Computer Science Departments of the University of Southern Louisiana (USL) and Southern University (SU) pursuant to a contract with NASA. Presented are only basic identification data concerning the contract activities since subsequent entries within the Working Paper Series will be oriented specifically toward a detailed development and presentation of plans, methodologies, and results of each contract activity. Also included is a table of contents of the entire USL/DBMS NASA/RECON Working Paper Series.

Dominick, Wayne D.↗
NASA NTRS1980

Magnetohydrodynamic perturbations of Robertson-Walker universes and of anisotropic Bianchi type-I universes

Magnetohydrodynamic (MHD) perturbations in flat Robertson-Walker universes were analyzed, emphasizing their effects on galaxy formation. The Newtonian approximation is used. There is no increase in the growth rates beyond those of the usual perturbed Robertson-Walker models; the MHD modes extract as much energy as they contribute. Some global properties of fully MHD Bianchi I relativistic models are analyzed including vorticity, fluid accelerations, and dissipative effects. The time dependence of perturbations of a fully MHD diagonal Bianchi I cosmology is studied, with an enhanced growth rate of the density contrast of t found which is still not exponential Jeans-type growth. This indicates that a more detailed analysis is needed if a solution to the galaxy formation problem in MHD cosmologies is to be found.

Fennelly, A. J.↗
NASA NTRS1971

Ceramics in severe environments; Proceedings of the Sixth University Conference on Ceramic Science, North Carolina State University, Raleigh, N.C., December 7-9, 1970.

The papers examine new findings and present technologically significant environmental effects and limitations relating to ceramic materials, their properties, and their uses. The effects of thermal and thermochemical factors, thermal shock, concentrated stresses, and severe mechanical environments are considered, as well as stress corrosion, hydrostatic stress, and electromagnetic and nuclear radiation environments. Individual items are abstracted in this issue.

Kriegel, W. W.↗
NASA NTRS1973

International Symposium on Combustion, 14th, Pennsylvania State University, University Park, Pa., August 20-25, 1972, Proceedings.

Some elementary steps for the formation and destruction of nitric oxide in the H-N-O system, high-temperature oxidation of hydrogen by nitrous oxide in shock waves, and high-temperature fast-flow reactor studies of metal-atom oxidation kinetics are among the topics covered in papers concerned with elementary reactions in combustion. Other areas covered include oscillatory, turbulent, and supersonic combustion; flames in furnaces and combustors; and pollutant formation and destruction in flames. Individual items are announced in this issue.

Source record↗
DOE OSTI2026

Probabilistic inference in very large universes

Our current favored cosmological theories allow for the striking and controversial possibility that the observable universe is just a small part of a much larger universe in which parameters that describe the effective, low-energy laws of physics vary from one region to another. The controversy is largely driven by the fact that such a “very large universe” is mostly observationally inaccessible to us, so the issue arises of how we can reasonably assess a theory that describes such a universe. In this paper, we propose a Bayesian method for theory assessment based on theory-generated probability distributions for our observations. We focus on the principles that define this method, leaving aside concerns about how, in practice, one would carry out the required calculations. (One important issue that we set aside is the measure problem.) We argue that cosmological theories can be tested by the standard method of Bayesian updating, but we need to use theoretical predictions for “first-person” probabilities—that is, probabilities that we should use for our observations, taking into account all relevant selection effects. These selection effects can vary from one observer to another and can vary with time, so, in principle, first-person probabilities are defined for each observer instant—an observer at a specific instant of time. Calculations of first-person probabilities should take into account everything that the observer believes about herself and her surroundings, which we refer to as her subjective state. If the universe is very large, a theory might predict that there are many observer instants in the same subjective state; we argue that first-person probabilities should be calculated using a principle of self-locating indifference (PSLI), the assumption that any real observer should make predictions for her future as if she were chosen randomly and uniformly from the theoretically predicted observer instants that share her subjective state. We believe the PSLI is intuitively very reasonable, but we also argue that, if the theory is correct, the use of this principle maximizes the expected fraction of observers who will make correct predictions. A further complication is that cosmological theories are not expected to fully predict the detailed properties of the universe, but rather will predict a set of possible universes, each with a probability. Different possible universes will generically have different numbers of observers. We argue that, in the calculation of first-person probabilities, the probability for each possible universe should be weighted by the number of observer instants in the specified subjective state that it contains. These issues have been controversial in the literature, so we also provide a rebuttal to the claim that principles like the PSLI involve a “selection fallacy”; a rebuttal to what we dub the principle of required certainty; an argument rejecting theories that predict a preponderance of Boltzmann brains; a rebuttal to a parable about humans and Jovians used by Hartle and Srednicki to argue that assumptions of typicality can lead to absurd consequences; and, finally, a discussion about how the use of “old evidence” can be fit into a Bayesian mold.

Azhar, Feraz [University of Notre Dame, IN (United↗
NASA NTRS1989

NASA/USRA University Advanced Design Program Fifth Annual Summer Conference

The NASA/USRA University Advanced Design Program is a unique program that brings together NASA engineers, students, and faculty from United States engineering schools by integrating current and future NASA space/aeronautics engineering design projects into the university curriculum. The Program was conceived in the fall of 1984 as a pilot project to foster engineering design education in the universities and to supplement NASA's in-house efforts in advanced planning for space and aeronautics design. Nine universities and five NASA centers participated in the first year of the pilot project. Close cooperation between the NASA centers and the universities, the careful selection of design topics, and the enthusiasm of the students has resulted in a very successful program than now includes forty universities and eight NASA centers. The study topics cover a broad range of potential space and aeronautics projects which could be undertaken during a 20-30 year period beginning with the deployment of the Space Station Freedom scheduled for the mid1990s. Both manned and unmanned endeavors are embraced, and the systems approach to the design problem is emphasized. The student teams pursue the chosen problem during their senior year in a one or two semester capstone design course and submit a comprehensive written report at the conclusion of the project. Finally, student representatives from each of the universities summarize their work in oral presentations at the annual Summer Conference, held at one of the NASA centers and attended by the university faculty, NASA and USRA personnel, and aerospace industry representatives.

Source record↗
DOE OSTI2025

On tests for baby universes in AdS/CFT

To address a puzzle by Antonini and Rath — where a single CFT state has two bulk duals, one with a baby universe and one without — Engelhardt and Gesteau recently devised a test for baby universes in AdS/CFT. Using the extrapolate dictionary, they showed that the boundary dual of a bulk swap test favored bulk spacetimes without a baby universe, providing evidence against their semiclassical validity. However, recent work suggests that holographic maps should post-select on such closed universes, and we argue that this is consistent with the extrapolate dictionary. We therefore construct a new holographic map for bulk states with baby universes and use this to show that the swap test cannot distinguish between Antonini and Rath’s two candidate bulk duals. This not only allows for a valid semiclassical description of the baby universe, but also enables the application of recent techniques for including observers in holographic maps.

AdS-CFT correspondence↗
NASA NTRS1988

NASA's new university engineering space research programs

The objective of a newly emerging element of NASA's university engineering programs is to provide a more autonomous element that will enhance and broaden the capabilities in academia, enabling them to participate more effectively in the U.S. civil space program. The programs utilize technical monitors at NASA centers to foster collaborative arrangements, exchange of personnel, and the sharing of facilities between NASA and the universities. The elements include: the university advanced space design program, which funds advanced systems study courses at the senior and graduate levels; the university space engineering research program that supports cross-disciplinary research centers; the outreach flight experiments program that offers engineering research opportunities to universities; and the planned university investigator's research program to provide grants to individuals with outstanding credentials.

Sadin, Stanley R.↗
NASA NTRS1991

Dark matter in the universe

What is the quantity and composition of material in the Universe? This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand. Most of the radiation in the Universe does not give off detectable radiation; it is dark. The dark matter associated with bright galaxies contributes somewhere between 10 and 30 percent of the critical density; baryonic matter contributes between 1.1 and 12 percent of the critical. The case for the spatially flat, Einstein-de Sitter model is supported by three compelling theoretical arguments - structure formation, the temporal Copernican principle, and inflation - and by some observational data. If Omega is indeed unity, or even just significantly greater than 0.1, then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark matter candidates: an axion of mass 10 (exp -6) eV to 10 (exp -4) eV; a neutrino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either planned or are underway.

Turner, Michael S.↗