News and Events

John Howell
Please join us for a colloquium titled “Breaking the Law: Pushing Physics Beyond its Man-Made Limitations” at 12:00 PM online, or in C215 ESC.
Thumbnail of Back from Bennu
Back from asteroid 101955 Bennu, a 110-pound, 31-inch wide sample return capsule rests in a desert on planet Earth in this photo, taken at the Department of Defense Utah Test and Training Range near Salt Lake City last Sunday, September 24. Dropped off by the OSIRIS-Rex spacecraft, the capsule looks charred from the extreme temperatures experienced during its blistering descent through Earth's dense atmosphere. OSIRIS-Rex began its home-ward journey from Bennu in May of 2021. Delivered to NASA’s Johnson Space Center in Houston on September 25, the capsule's canister is expected to contain an uncontaminated sample of about a half pound (250 grams) of Bennu's loosely packed regolith. Working in a new laboratory designed for the OSIRIS-REx mission, scientists and engineers will complete the canister disassembly process, and plan to unveil the sample of the near-Earth asteroid in a broadcast event on October 11.
Mount Timpanogos with sky above
Check current conditions and historical weather data at the ESC.
Image for Sounding out the Deep: Traci Neilsen’s Trip to the North Atlantic
A recent research adventure took Dr. Traci Neilsen and two students to the North Atlantic Ocean. Neilsen, an associate professor of physics at BYU, and her team apply artificial intelligence to noises in the ocean to classify the seabed.
Image for Reveling in Uncertainty
Despite the inherent time constraints of engaging undergraduate and graduate students in research, Scott Bergeson enjoys teaching this “seek and find” principle to his students, a principle that has become his philosophy for life.
Image for BYU Acoustics Records Artemis Launch
A group of BYU students and professors gathered acoustical recordings of at the world’s most powerful rocket launch.

Selected Publications

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BYU Authors: Kyle Larsen, Stefan Lehnardt, Bryce Anderson, Joseph Rowley, Richard Vanfleet, and Robert Davis, published in Rev. Sci. Instrum.

Estimating the elastic modulus and strength of heterogeneous films requires local measurement techniques. For local mechanical film testing, microcantilevers were cut into suspended many-layer graphene using a focused ion beam. An optical transmittance technique was used to map thickness near the cantilevers, and multipoint force–deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers. These data were used to estimate the elastic modulus of the film by fitting the compliance at multiple locations along the cantilever to a fixed-free Euler–Bernoulli beam model. This method resulted in a lower uncertainty than is possible from analyzing only a single force–deflection. The breaking strength of the film was also found by deflecting cantilevers until fracture. The average modulus and strength of the many-layer graphene films are 300 and 12 GPa, respectively. The multipoint force–deflection method is well suited to analyze films that are heterogeneous in thickness or wrinkled.

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BYU Authors: Emily D. Golightly, Brian E. Anderson, Adam D. Kingsley, Rylee Russell, and Rebekah Higgins, published in Appl. Acoust.

Time reversal is a process where a sound is recorded at a specific location, temporally reversed, and then played back to focus at the same location as the original recording. This paper will focus on the use of scatterers placed within a wavelength (the assumed near field) of time reversal focusing to achieve super resolution. A one-dimensional pipe system is used with extensions that simulate the increased path length due to diffraction around an object. This longer path length, if unaccounted for, leads to a decrease in the effective wave speed. As the effective wave speed decreases, the spatial extent of the focusing decreases, creating super resolution. Although previous work refers to the scattering property of the medium as key to achieving super resolution, this paper shows that the path extending properties of scatterers only show super resolution when the distance between measurements does not take into account the longer path length traveled around scatterers. Consequently, it supports the understanding that resonances within the medium are more likely to yield super resolution focusing than using passive scattering.

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BYU Authors: Mark K Transtrum, published in Rep. Prog. Phys.

Complex models in physics, biology, economics, and engineering are often sloppy, meaning that the model parameters are not well determined by the model predictions for collective behavior. Many parameter combinations can vary over decades without significant changes in the predictions. This review uses information geometry to explore sloppiness and its deep relation to emergent theories. We introduce the model manifold of predictions, whose coordinates are the model parameters. Its hyperribbon structure explains why only a few parameter combinations matter for the behavior. We review recent rigorous results that connect the hierarchy of hyperribbon widths to approximation theory, and to the smoothness of model predictions under changes of the control variables. We discuss recent geodesic methods to find simpler models on nearby boundaries of the model manifold-emergent theories with fewer parameters that explain the behavior equally well. We discuss a Bayesian prior which optimizes the mutual information between model parameters and experimental data, naturally favoring points on the emergent boundary theories and thus simpler models. We introduce a 'projected maximum likelihood' prior that efficiently approximates this optimal prior, and contrast both to the poor behavior of the traditional Jeffreys prior. We discuss the way the renormalization group coarse-graining in statistical mechanics introduces a flow of the model manifold, and connect stiff and sloppy directions along the model manifold with relevant and irrelevant eigendirections of the renormalization group. Finally, we discuss recently developed 'intensive' embedding methods, allowing one to visualize the predictions of arbitrary probabilistic models as low-dimensional projections of an isometric embedding, and illustrate our method by generating the model manifold of the Ising model.

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BYU Authors: Denise C Stephens, Emma Campbell, Jarrod Hansen, Eric G Hintz, and Jacob S Jensen, published in Mon. Not. Roy. Astron. Soc.

We present the discovery and characterization of six short-period, transiting giant planets from NASA’s Transiting Exoplanet Survey Satellite (TESS) — TOI-1811 (TIC 376524552), TOI-2025 (TIC 394050135), TOI-2145 (TIC 88992642), TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467). All six planets orbit bright host stars (8.9 <G < 11.8, 7.7 <K < 10.1). Using a combination of time-series photometric and spectroscopic follow-up observations from the TESS Follow-up Observing Program (TFOP) Working Group, we have determined that the planets are Jovian-sized (RP = 0.99-1.45 RJ), have masses ranging from 0.92 to 5.26 MJ, and orbit F, G, and K stars (4766 ≤ Teff ≤ 7360 K). We detect a significant orbital eccentricity for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days, 0.394$^{+0.035}_{-0.038}$), TOI-2145 b (P = 10.261 days, e = $0.208^{+0.034}_{-0.047}$), and TOI-2497 b (P = 10.656 days, e = $0.195^{+0.043}_{-0.040}$). TOI-2145 b and TOI-2497 b both orbit subgiant host stars (3.8 < log  g <4.0), but these planets show no sign of inflation despite very high levels of irradiation. The lack of inflation may be explained by the high mass of the planets; $5.26^{+0.38}_{-0.37}$ MJ (TOI-2145 b) and 4.82 ± 0.41 MJ (TOI-2497 b). These six new discoveries contribute to the larger community effort to use TESS to create a magnitude-complete, self-consistent sample of giant planets with well-determined parameters for future detailed studies.

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BYU Authors: Kent L. Gee, Grant W. Hart, Carson F. Cunningham, Mark C. Anderson, Michael S. Bassett, Logan T. Mathews, J. Taggart Durrant, and Levi T. Moats, published in JASA Express Letters

To improve understanding of super heavy-lift rocket acoustics, this letter documents initial findings from noise measurements during liftoff of the Space Launch System's Artemis-I mission. Overall sound pressure levels, waveform characteristics, and spectra are described at distances ranging from 1.5 to 5.2 km. Significant results include: (a) the solid rocket boosters' ignition overpressure is particularly intense in the direction of the pad flame trench exit; (b) post-liftoff maximum overall levels range from 127 to 136 dB, greater than pre-launch predictions; and (c) the average maximum one-third-octave spectral peak occurred at 20 Hz, causing significant deviation between flat and A-weighted levels.

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BYU Authors: A. V. Mosenkov and Z. Shakespear, published in Astron. Lett.

have applied the method of star counts with Wolf diagrams to determine the interstellar extinction in five Galactic cirri in Sloan Digital Sky Survey (SDSS) Stripe 82. For this purpose, we have used the photometry of stars in the GALEX NUV filter and the photometry of red dwarfs in five SDSS bands and four SkyMapper Southern Sky Survey DR2 bands. We have identified the cirri as sky regions with an enhanced infrared emission from the Schlegel+1998 map. The extinction in them has been calculated relative to the nearby comparison regions with a reduced emission. The results for different filters agree well, giving the range of distances and the extinction law for each cirrus. The distances in the range 140-415 pc found are consistent with the 3D reddening maps. In the range between the B and V filters the extinctions found are consistent with the estimates from Schlegel+1998 for the Cardelli+1989 extinction law with R-V = 3.1. However, the extinctions found for all of the filters are best described not by the Cardelli+1989 extinction law with some R-V, but by the inverse proportionality of the extinction and wavelength with its own coefficient for each cirrus. In one of the cirri our results suggest a very slight decrease in extinction with wavelength, i.e., a large contribution of gray extinction. In the remaining cirri a manifestation of gray extinction is not ruled out either. This is consistent with the previous measurements of the extinction law far from the Galactic midplane.