Science Series: Science in the Cross Hairs
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Arxiv:2007.09714V1 [Gr-Qc] 19 Jul 2020 Tem PSR J0737-3039A/B
Probing Noncommutative Gravity with Gravitational Wave and Binary Pulsar Observations Leah Jenks,1 Kent Yagi,2 and Stephon Alexander1 1Brown Theoretical Physics Center and Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island, 02903 2Department of Physics, University of Virginia, P.O. Box 400714, Charlottesville, VA 22904-4714, USA (Dated: July 21, 2020) Noncommutative gravity is a natural method of quantizing spacetime by promoting the spacetime coordinates themselves to operators which do not commute. This approach is motivated, for exam- ple, from a quantum gravity perspective, among others. Noncommutative gravity has been tested against the binary black hole merger event GW150914. Here, we extend and improve upon such a previous analysis by (i) relaxing an assumption made on the preferred direction due to noncommuta- tivity, (ii) using posterior samples produced by the LIGO/Virgo Collaborations, (iii) consider other gravitational wave events, namely GW151226, GW170608, GW170814 and GW170817, and (iv) consider binary pulsar observations. Using Kepler's law that contains the noncommutative effect at second post-Newtonian order, we derive corrections to the gravitational waveform phase and the pericenter precession. Using the gravitational wave and double pulsar binary observations, we find bounds on a space-time noncommutative tensor θ0i in terms of the preferred frame direction with respect to the orientation of each binary. We find that the gravitational wave bounds are stronger than the binary pulsar one by an order of magnitude and the noncommutative tensor normalized by the Planck length and time is constrained to be of order unity. I. INTRODUCTION of noncommutative gravity stems from these theories. -
Nfap Policy Brief » O C T O B E R 2017
NATIONAL FOUNDATION FOR AMERICAN POLICY NFAP POLICY BRIEF» O CTOBER 2017 IMMIGRANTS AND NOBEL PRIZES : 1901- 2017 EXECUTIVE SUMMARY Immigrants have been awarded 39 percent, or 33 of 85, of the Nobel Prizes won by Americans in Chemistry, Medicine and Physics since 2000. In 2017, the sole American winner of the Nobel Prize in Chemistry was an immigrant, Joachim Frank, a Columbia University professor born in Germany. Immigrant Reiner Weiss, who was born in Germany and came to the United States as a teenager, was awarded the 2017 Nobel Prize in Physics, sharing it with two other Americans, Kip S. Thorne and Barry C. Barish. In 2016, all 6 American winners of the Nobel Prize in economics and scientific fields were immigrants. These achievements by immigrants point to the gains to America of welcoming talent from across the globe. It does not mean America should welcome only Nobel Prize winners. Such a policy would be impossible to implement, since most immigrant Nobel Prize winners enter the United States many years before being awarded this honor. Most people immigrate to another country in their 20s, particularly employment-based immigrants, who either study in America or come here to work shortly after obtaining a degree abroad. The average of age of Nobel Prize winners at the time of the award is 59.5 years, according to economist Mark J. Perry.1 Table 1 Immigrant Nobel Prize Winners in Chemistry, Medicine and Physics Since 2000 Immigrant Nobel Winners Since 2000 33 of 85 American winners have been immigrants Percentage of Immigrant Winners Since 2000 39% Source: Royal Swedish Academy of Sciences, National Foundation for American Policy, George Mason University Institute for Immigration Research. -
Physicists at Work Interactions
A Inter ctions across physics and education September/October 2007 Focal Point Physicists at Work Inside: Career Paths, Profiled Physics Majors, Uncovered Writing About Science and introducing “Homer Dodge's Notebook” Interactions Inter ctions MAGAZINE across physics and education Issue Editor: John S. Rigden Managing Editor: Daryl Malloy Production Editor: Lissa Reynolds About INTERACTIONS Assistant Editor: Steve Davolt Interactions is a general-interest magazine about physics education. Our mission is to inform and stimulate diverse conversations on teaching and Design: Matthew Payne learning by publishing thought-provoking news, analysis, and commentary Contributing Design: Ayah Oweis on the people, programs, and policies that interact to influence scientific practices and knowledge—and, ultimately, human destiny. Contributing Editors Jane Chambers, Rachel Ivie, Rachel Safier, Reader Comments Pamela Brown, Patrick Mulvey, Martha Heil The editors welcome your response. Send comments, questions or suggestions Publisher: Toufic M. Hakim to [email protected] or mail letters to Interactions Forum, One Physics Communications Director: Robert Headrick Ellipse, 5th Floor, College Park, MD 20740. Please include your full name, mailing address, and daytime contact information. Space is limited and all Editorial Advisory Panel Juan Burciaga published comments are subject to editing. Whitman College, WA Christopher Chiaverina Contributor Guidelines New Trier High School, IL Although most of the articles are commissioned by the editors, we encourage Warren Hein writer queries and story ideas. Email your query, and attach any writing samples, American Association of Physics Teachers, MD to [email protected]. Or mail the letter along with samples to Interactions Robert Hilborn Editor, One Physics Ellipse, College Park, MD 20740. -
Supernova Physics with Gravitational Waves: Newborn Black Holes Are “Kicked”
Supernova physics with gravitational waves: Newborn black holes are “kicked” Richard O’Shaughnessy [email protected] 614 906 9649 Davide Gerosa [email protected] 626 395 6829 Daniel Wysocki [email protected] ! ! Accepted for publication in Physical Review Letters Poster 317.07 [see iPoster] June 5, AAS 2 3 GW151226: Gravitational waves from a black hole binary B. P.• ABBOTTGW151226et al. is the second, less massive binary black hole confidently detectedPHYS. by REV. LIGO X 6, 041015 (2016) GW151226 Abbott et al, PRX 6, 041015 (2016) ; PRL 118 221101 (2017) FIG. 4. Posterior probability densities of the masses, spins, and distance to the three events GW150914, LVT151012, and GW151226. source For the two-dimensional distributions, the contours show 50% and 90% credible regions. Top left panel: Component masses m1 and source source source m2 for the three events. We use the convention that m1 ≥ m2 , which produces the sharp cut in the two-dimensional source 0.3 distribution. For GW151226 and LVT151012, the contours follow lines of constant chirp mass (M 8.9−þ0.3 M and source 1.4 ¼ ⊙ M 15:1−þ1.1 M , respectively). In all three cases, both masses are consistent with being black holes. Top right panel: The mass and¼ dimensionless⊙ spin magnitude of the final black holes. Bottom left panel: The effective spin and mass ratios of the binary components. Bottom right panel: The luminosity distance to the three events. following section and are consistent with our expect- closely mirror the original analysis of GW150914, as ations for an astrophysical BBH source. -
MY SO October Showdown Rules
S P A C E - O C T O B E R 2 0 2 0 MY SO STEM SHOWDOWN C O N T E N T , R E C O M M E N D E D M A T E R I A L S & S C O R I N G STEM SHOWDOWN CONTENT The STEM Showdown will consist of a series of online multiple-choice questions. Middle school (Grade 6-9) participant questions will center around the properties and evolution of stars and galaxies as well as their observation using different portions of the electromagnetic spectrum (e.g., Radio, Infrared, Visible, Ultraviolet, X-Ray, Gamma Ray). While high school (Grades 9-12) participants will focus on Star and Galaxy Formation and Evolution. A Showdown participant will have 55- minutes to answer as many questions as possible. The middle school (Grades 6-9) content and skills covered by the Showdown this month is as follows: 1.Stellar and galactic evolution 2.Spectral classification of stars 3.Hubble classification of galaxies 4.Observation using multiple portions of the electromagnetic spectrum 5.The relationship between stellar temperature, radius, and luminosity 6.Magnitude and luminosity scales, distance modulus, inverse square law 7.Identification of the stars, constellations, and deep sky objects included in the list below as they appear on star charts, H-R diagrams, portable star labs, photos, or planetariums. Note: Constellations are underlined; Stars are boldface; Deep Sky Objects are italicized. a.Andromeda: M31 (Andromeda Galaxy) b.Aquila: Altair c.Auriga: Capella d.Bootes: Arcturus e.Cancer: DLA0817g f.Canis Major: Sirius g.Canis Minor: Procyon h.Centaurus: NGC5128 i.Coma Berenices: NGC4676, NGC4555 j.Corvus: NGC4038/NGC4039 k.Crux: Dragonfish Nebula l.Cygnus: Deneb m.Dorado: 30 Doradus, LMC n.Gemini: Castor, Pollux o.Lyra: Vega p.Ophiuchus: Zeta Ophiuchi, Rho Ophiuchi cloud complex q.Orion: Betelgeuse, Rigel & M42 (Orion Nebula) r.Perseus: Algol, NGC1333 Science Olympiad, Inc. -
David Norman Schramm October 25, 1945–December 19, 1997
NATIONAL ACADEMY OF SCIENCES D AVID NORMAN SCHRAMM 1 9 4 5 — 1 9 9 7 A Biographical Memoir by M I C H A E L S . T URNER Any opinions expressed in this memoir are those of the author and do not necessarily reflect the views of the National Academy of Sciences. Biographical Memoir COPYRIGHT 2009 NATIONAL ACADEMY OF SCIENCES WASHINGTON, D.C. DAVID NORMAN SCHRAMM October 25, 1945–December 19, 1997 B Y MICHAEL S . TURNER “ E LIVED LARGE IN ALL DIMENSIONS.” That is how Leon HLederman began his eulogy of David N. Schramm at a memorial service held in Aspen, Colorado, in December 1997. His large presence in space went beyond his 6-foot, 4-inch, 240-pound frame and bright red hair. In spite of his tragic death in a plane crash at age 52, Schramm lived large in the time dimension, too. At 18, he was married, a father, and a freshman physics major at MIT. After receiving his Ph.D. in physics from Caltech at 25, Schramm joined the faculty at the University of Texas at Austin. He left for Chicago two years later, and became the chair of the Astronomy and Astrophysics Department at the University of Chicago at age 2. He was elected to the National Academy of Sciences in 1986 at 40, became chair of the National Research Council’s Board on Physics and Astronomy at 47, and two years later became vice president for research at Chicago. He also had time for mountain climbing, summiting the highest peaks in five of the seven continents (missing Asia and Antarctica), driving a red Porsche with license plates that read “Big Bang,” and flying—owning four airplanes over his 12-year flying career and logging hundreds of hours annually. -