Thanks to the Space Telescope Science Institute (STScI) and NASA’s James Webb Space Telescope for supporting this video! In particular, thanks to Dan Coe of STScI for taking the time to chat with me about what we do and don’t know about baby galaxies and how they're born. Thanks to everyone who supports MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon supporters here: http://www.minutephysics.com/supporters.html Music by Nathaniel Schroeder, http://www.soundcloud.com/drschroeder REFERENCES ... https://www.youtube.com/watch?v=kif4ON6QOPE

Thanks to https://brilliant.org/minutephysics for sponsoring this video! Check out their black hole course at http://brilliant.org/minutephysicsblackhole Support MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon Supporters: http://www.minutephysics.com/supporters/ This video is about how efficient various reactions are at converting mass to energy (as we know from the Einstein mass-energy equivalence of E=mc^2). Antimatter is very efficient but it is not naturally-occurring. Chemical reactions like fire or explosions are very inefficient. Nuclear fission and nuclear fusion are better, but not amazing on an absolute scale. Non-rotating black holes (Schwarzschild) and rotating (Kerr) are by far the most efficient, due to their accretion disks and very small radius of their innermost stable circular orbits. REFERENCES: Periodic Videos Hydrogen Explosion in slow motion: https://www.youtube.com/watch?v=qOTgeeTB_kA ... https://www.youtube.com/watch?v=t-O-Qdh7VvQ

This video was made in collaboration with the US Census Bureau and fact-checked by Census Bureau scientists. Any opinions and errors are my own. For more information, visit https://census.gov/about/policies/privacy/statistical_safeguards.html or search "differential privacy" at http://census.gov. REFERENCES Differential Privacy in the Wild: http://www.vldb.org/pvldb/vol9/p1611-machanavajjhala.pdf Harvard University Privacy Tools Project: https://privacytools.seas.harvard.edu/differential-privacy Simons Institute Workshop Video Recordings and Articles Archive: https://simons.berkeley.edu/workshops/schedule/6281 Cynthia Dwork (key inventor of Differential Privacy), giving a great intro talk about differential privacy: https://www.youtube.com/watch?v=lg-VhHlztqo Shiva P Kasiviswanathan and Adam Smith. On the semantics of differential privacy: A Bayesian formulation. Journal of Privacy and Confidentiality, 6(1):1–16, 2014. Shiva Prasad Kasiviswanathan and Adam Smith. On the ‘semantics’ of differential privacy: A Bayesian formulation. 2015. https://arxiv.org/abs/0803.3946 Daniel Kifer and Ashwin Machanavajjhala. A rigorous and customizable framework for privacy. In ACM Symposium on Principles of Database Systems (PODS), 2012. Daniel Kifer and Ashwin Machanavajjhala. Pufferfish: A framework for mathematical privacy definitions. ACM Trans. Database Syst., 39(1):3, 2014. Support MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon Supporters: http://www.minutephysics.com/supporters/ MinutePhysics is on twitter - @minutephysics And facebook - http://facebook.com/minutephysics And Google+ (does anyone use this any more?) - http://bit.ly/qzEwc6 Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Created by Henry Reich ... https://www.youtube.com/watch?v=pT19VwBAqKA

Thanks to the Heising-Simons foundation for their support: https://www.hsfoundation.org (their COVID-19 grants: https://www.hsfoundation.org/grants/covid-19-response-grants/ ) Check out https://aatishb.com/maskmath to explore and for references. This video is about how masks (whether surgical, or N95, or cloth) are counterintuitive and actually work much better epidemiologically than one might expect. Masks do double-duty, and the fraction of interactions with masks is much higher than the fraction of people wearing masks, so partially adopted, partially effective masks are able to reduce the basic reproduction number surprisingly well. REFERENCES: Aatish’s detailed writeup on github: https://github.com/aatishb/maskmath/blob/master/model/mathmodel.ipynb Amid the Coronavirus Crisis, a Regimen for Re-entry: https://www.newyorker.com/science/medical-dispatch/amid-the-coronavirus-crisis-a-regimen-for-reentry Face Masks Against COVID-19: An Evidence Review https://www.preprints.org/manuscript/202004.0203/v3 Mask FAQ Test Results: https://www.maskfaq.com/test-results The Effect of Mask Use on the Spread of Influenza During a Pandemic: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1539-6924.2010.01428.x Calibrated Intervention and Containment of the COVID-19 Pandemic: https://arxiv.org/ftp/arxiv/papers/2003/2003.07353.pdf Cloth Mask Breathability and Filtration Efficiency Technical Report: https://static1.squarespace.com/static/5e8126f89327941b9453eeef/t/5f2c4463a5c9f75a38d2b26f/1596736614213/N95DECON_cloth_mask_breathability_filtrationtechnical_report_v1_200804.pdf What kind of mask should I be wearing to protect against COVID-19? http://built-envi.com/what-kind-of-mask-should-i-be-wearing-to-protect-against-covid-19/ Masks for all? The science says yes. https://www.fast.ai/2020/04/13/masks-summary/ The Real Reason to Wear a Mask: https://medium.com/the-atlantic/the-real-reason-to-wear-a-mask-e6405abbc484 Support MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon Supporters: http://www.minutephysics.com/supporters/ MinutePhysics is on twitter - @minutephysics And facebook - http://facebook.com/minutephysics And Google+ (does anyone use this any more?) - http://bit.ly/qzEwc6 Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Created by Henry Reich ... https://www.youtube.com/watch?v=Y47t9qLc9I4