Science Summary video for this section2 April: Scientists describe how the dinosaur-killing impact is an origin of neotropical rainforests like the Amazonia and replaced its species composition.[1]
6 April: A study finds that carbon emissions from Bitcoin mining within China are about to exceed the total annual carbon emissions of countries like Italy (within an estimated ~3 years).[3]
6 April
A study finds that carbon emissions from Bitcoin mining in China – where a majority of the proof-of-work algorithm that generates current economic value is computed, largely fueled by nonrenewable sources – have accelerated rapidly, would soon exceed total annual emissions of European countries like Italy and Spain in 2016 and interfere with climate change mitigation commitments.[4][3]
COVID-19 pandemic: Scientists report the "estimated incidence of a neurological or psychiatric diagnosis in the following 6 months" after diagnosed COVID-19 infection was 33.62% with 12.84% "receiving their first such diagnosis" and higher risks being associated with COVID-19 severity.[5][6]
NOAA reports the largest annual increase in methane emissions since records began, with a rise of 14.7 parts per billion (ppb) in 2020.[11]
A study finds that humans engaged in problem-solving tend to overlook subtractive changes, including those that are critical elements of efficient solutions. This tendency to solve by creating or adding elements is shown to intensify with higher cognitive loads in the case of individuals.[12][13]
Scientists confirm, with new genomic data, that initial European modern humans mixed with Neanderthals with continuity to later people in Eurasia and report that such admixture appears to have been more common than previously thought.[16][17]
8 April – Scientists report rough spectral signatures of 958 molecules that may be involved in the atmospheric production or consumption of phosphine, which could prevent misassignments and, if accuracy is improved, be used in future detections and identifications of molecules on other planets such as Venus.[18][19] On 10 April, a news report informs about a launched NASA-funded mission to design and test robotic balloons for future scientific exploration of Venus.[20] On 19 April scientists who reported the detection of well-established or likely biosignature, monophosphine, on Venus publish a preprint recovering the detection of PH3 in the Venusian atmosphere – which was challenged by critical studies – with the proposed SO2-attribution alternative being inconsistent with the available data.[21]
Scientists present a tool for epigenome editing, CRISPRoff, that can heritably silence the gene expression of "most genes" and allows for reversible modifications.[28][29]
Scientists develop a prototype and design rules for both-sides-contacted siliconsolar cells with conversion efficiencies of 26% and above, Earth's highest for this type of solar cell.[33][34]
In a preprint, an astronomer describes for the first time how one could search for quantum communicationtransmissions sent by ETI using existing telescope and receiver technology. He also provides arguments for why future searches of SETI should also target interstellar quantum communications.[38][39]
COVID-19 pandemic: Scientists report that patients who consistently met scientific guidelines of 150+ min/week exercise or similar physical activity had a smaller risk of hospitalisation and death due to COVID-19, even when considering likely risk factors such as elevated BMI.[40][41]
14 April – Astronomers report that the supermassive black hole M87*, first, and to date, the only black hole to be imaged, will be further studied by many observatories from around the world and present results of simultaneous observations and their subsequent analysis.[42][43]
19 April: The semi-autonomous Ingenuity performs the first powered aircraft flight on another planet in human history.[44]29 April: The first, core module of the Chinese Tiangong space station is put into orbit.[45]
Biologists report that an estimated 2.5 billion adult Tyrannosaurus rex dinosaurs roamed the Earth over the 2.4 million years of their existence.[54][55]
A study assesses that only 3% of the planet's terrestrial surface is ecologically and faunally "intact", with low human footprint and healthy populations of native animal species.[56][57]
Researchers demonstrate the whitest ever paint formulation, which reflects up to 98.1% of sunlight and could be used in place of air conditioners.[58][59]
19 April – NASA's Ingenuity helicopter, part of the Mars 2020 mission, performs the first powered aircraft flight on another planet in history. The test location is named "Wright Brothers Field".[63][64][44]
Scientists show that a class of warp drives that are slower than light, could control the rate of time within the spaceship and are sourced from positive energy could in principle possibly be constructed based on known physical principles. Furthermore, they provide a new argument "why superluminal warp drive solutions may always violate weak energy conditions" and that the concept proposed in a study published in March (see above) "likely forms a new class of warp drive spacetimes".[68][69]
Scientists report that of ~39 million groundwater wells 6-20% are at high risk of running dry if local groundwater levels decline by a few meters, or – as with many areas and possibly more than half of major aquifers[72] – continue to decline.[73][74]
27 April – Astronomers report the discovery of TOI-1431b, an "ultra-hot Jupiter" with a dayside temperature of ~3,000K (2,700 °C), making it one of the hottest exoplanets found to date.[75][76]
29 April – The first, core module of the Chinese Tiangong space station, Tianhe, is placed in low Earth orbit. It is one of three permanent modules intended to be fully assembled in 2022 for a designed lifespan of 10–15 years, is 16.6 m in size and could host three astronaut scientists.[45]
A study assesses benefits of fast action to reduce methane emissions when compared to slower climate change mitigation of this form.[84] On 6 May a U.N. report assesses benefits and costs of rapidly mitigating methane emissions.[85]
Researchers find that China's CO2 emissions surpassed that of all OECD countries combined for the first time in 2019.[88][89][90] On 20 May China's CO2 emissions are found to be 9% higher than pre-COVID-19-pandemic levels in 2021-Q1 with CO2 emissions from fossil fuels and cement production having grown by 14.5% compared to 2020.[88][91][92]
A new record for the smallest single-chip system is achieved, occupying a total volume of less than 0.1 mm3.[106][107]
Scientists estimate, with higher resolution data, that land-use change has affected 17% of land in 1960–2019, or when considering multiple change events 32%, "around four times" previous estimates and investigate its drivers.[108][109]
Scientists report that degrowth scenarios, where economic output either "declines" or declines in terms of contemporary economic metrics such as current GDP, have been neglected in considerations of 1.5 °C scenarios reported by the IPCC, finding that investigated degrowth scenarios "minimize many key risks for feasibility and sustainability compared to technology-driven pathways" with a core problem of such being feasibility in the context of contemporary political decision-making and rebound- and relocation-effects.[112][113][114]
The first use of a brain-computer interface to decode neural signals for handwriting is demonstrated and shows a character output speed of more than double the previous record.[116][117]
Archivists initiate a rescue mission to secure enduring access to humanity's largest public library of scientific articles, Sci-Hub, due to the site's increased legal troubles, using Web and BitTorrent technologies.[119]
20 May – A new record high resolution for atomic imaging is reported, with instrumental blurring reduced to less than 20 picometres.[125][126]
21 May – A study finds that papers in leading journals with findings that can't be replicated tend to be cited more than reproducible science. Results that are published unreproducibly are more likely to be wrong, may slow progress and, according to an author, "a simple way to check how often studies have been repeated, and whether or not the original findings are confirmed" is needed.[127][128][129]
Scientists at Japan's RIKEN institute demonstrate a "dry transfer technique" enabling the precise positioning of optical-quality carbon nanotubes, without the need for a solvent.[132][133]
Scientists elaborate mechanics of memory consolidation during sleep which may allow purposely enabling or strengthening this reactivation of experiences and information.[137][138]
27 May – The U.S. Department of Energy launches Perlmutter, a next-generation supercomputer with four exaflops of AI performance, the world's fastest when measured by 16-bit and 32-bit mixed-precision math.[141]
28 May
Biologists report the development of a new updated classification system for cell nuclei and find a way of transmuting one cell type into that of another.[142][143]
China's EAST tokamak sets a new world record for superheated plasma, sustaining a temperature of 120 million °C for 101 seconds and a peak of 160 million °C for 20 seconds.[144]
29 May – Medical scientists in Vietnam report a new, more contagious, form of the COVID-19 virus, that may be a mixture of the variants first detected in India and Britain.[145]
A new study provides experimental evidence of asymmetric response of interfacial water to applied electric field by using a single layer graphene electrode and a novel surface-sensitive non-linear spectroscopy technique with implications for various water-related processes such as in water purification.[149][150][151]
Scientists report that COVID-19 caused substantial changes to blood cells, sometimes persisting for months after hospital discharge, with implications for COVID-19 diagnostics and treatment.[152][153]
3 June – Scientists report that due to decreases in power generation efficiency of wind farms downwind of offshore wind farms, cross-national limits and potentials for optimization need to be considered in strategicdecision-making.[154][155]
Researchers from Google report a machine learning approach for microchip floorplanning that can outperform human designers.[167][168]
Researchers report the development of quantum nonlinear light microscopy with higher sensitivity and beyond the biological photodamage limit.[169][170]
Researchers report the development of the first quantum brain scanner which uses magnetic imaging and could become a novel whole-brain scanning approach.[176][177]
11 June: Biologists report that DNA polymerases, long thought to only transcribe DNA into DNA or RNA, can also write RNA segments into DNA.[179]
11 June – Biologists report that DNA polymerases, long thought to only transcribe DNA into DNA or RNA, can also write RNA segments into DNA. Polθ was found to promote RNA-templated DNA repair, with large implications for many fields of biology.[180][179]
14 June – Astronomers describe the largest known spinning structures in the Universe, consisting of "tendrils" of galaxies spanning hundreds of millions of light-years in length.[181][182][183]
15 June: Scientists complement extensive evidence that cosmetics are widely designed with formulations and disposals that are known to be harmful to human health and ecosystems, often containing PFAS.[184]
Scientists complement extensive evidence that cosmetics are widely designed with formulations and disposals that are known to be harmful to human health and ecosystems, often containing PFAS.[187][184]
18 June – The existence of a "pulse" in Earth's geological activity, occurring approximately every 27.5 million years, is reported. The next pulse is due in about 20.5 million years.[193][194]
19 June – A previously unknown comet, 2014 UN271, is reported by astronomers at the Dark Energy Survey. The object is estimated at between 100 and 200 km in size, potentially making it the largest comet ever discovered, and will pass as close as Saturn in January 2031.[195]
24 June – Astronomers provide a new calculation for when the first stars formed, placing this event between 250 and 350 million years after the Big Bang.[200][201]
Scientists report that natural immunity to COVID-19 via forms of prior infection combined with vaccination synergizes to extraordinarily large immune responses.[206][207]
A study concludes that public services are associated with higher human need satisfaction and lower energy requirements while contemporary forms of economic growth are linked with the opposite. Authors find that the contemporary economic system is structurally misaligned with goals of sustainable development and that to date no nation can provide decent living standards at sustainable levels of energy and resource use. They provide analysis about factors in social provisioning and assess that improving beneficial provisioning-factors and -infrastructure would allow for sustainable forms of sufficient need satisfaction.[217][218]
The smallest and most massive white dwarf ever seen is reported. The star, named ZTF J1901+1458, has a diameter of just 4,300 km but is 1.35 times the mass of the Sun.[221][222]
^Greaves, Jane S.; Richards, Anita M. S.; Bains, William; Rimmer, Paul B.; Clements, David L.; Seager, Sara; Petkowski, Janusz J.; Sousa-Silva, Clara; Ranjan, Sukrit; Fraser, Helen J. (19 April 2021). "Reply to: No evidence of phosphine in the atmosphere of Venus from independent analyses". Nature Astronomy. 5 (7): 636–639. arXiv:2104.09285. Bibcode:2021NatAs...5..636G. doi:10.1038/s41550-021-01424-x. S2CID233296859.
^Chang, Joseph Chee; Hahn, Nathan; Kim, Yongsung; Coupland, Julina; Breneisen, Bradley; Kim, Hannah S; Hwong, John; Kittur, Aniket (6 May 2021). "When the Tab Comes Due:Challenges in the Cost Structure of Browser Tab Usage". Proceedings of the 2021 CHI Conference on Human Factors in Computing Systems. Association for Computing Machinery. pp. 1–15. doi:10.1145/3411764.3445585. ISBN9781450380966. S2CID233987809.
^"China lands its Zhurong rover on Mars". BBC News. 15 May 2021. Archived from the original on 15 May 2021. Retrieved 15 May 2021. China has successfully landed a spacecraft on Mars, state media announced early on Saturday. The six-wheeled Zhurong robot was targeting Utopia Planitia...
^Utarini, Adi; Indriani, Citra; Ahmad, Riris A.; Tantowijoyo, Warsito; Arguni, Eggi; Ansari, M. Ridwan; Supriyati, Endah; Wardana, D. Satria; Meitika, Yeti; Ernesia, Inggrid; Nurhayati, Indah; Prabowo, Equatori; Andari, Bekti; Green, Benjamin R.; Hodgson, Lauren; Cutcher, Zoe; Rancès, Edwige; Ryan, Peter A.; O'Neill, Scott L.; Dufault, Suzanne M.; Tanamas, Stephanie K.; Jewell, Nicholas P.; Anders, Katherine L.; Simmons, Cameron P. (10 June 2021). "Efficacy of Wolbachia-Infected Mosquito Deployments for the Control of Dengue". New England Journal of Medicine. 384 (23): 2177–2186. doi:10.1056/NEJMoa2030243. ISSN0028-4793. PMC8103655. PMID34107180.
^Coussens, Thomas; Abel, Christopher; Gialopsou, Aikaterini; Bason, Mark G.; James, Tim M.; Orucevic, Fedja; Kruger, Peter (10 June 2021). "Modular optically-pumped magnetometer system". arXiv:2106.05877 [physics.atom-ph].
^Johannes Gutenberg-Universität. "Eruption of the Laacher See volcano redated". uni-mainz.de (Press release). Archived from the original on 1 July 2021. Retrieved 1 July 2021. That is 126 years earlier than the generally accepted dating based on sediments in the Meerfelder Maar from the Eifel region in Germany. ... This means that the [onset of the Younger Dryas] also occurred in Central Europe 130 years earlier, around 12,870 years ago respectively. This is in line with the onset of the cooling in the North Atlantic region identified in ice cores from Greenland. ... 'This strong cooling did not take place time transgressively, as previously thought, but rather synchronously over the entire North Atlantic and Central European region,' said Frederick Reinig.
^Reinig, Frederick; Wacker, Lukas; Jöris, Olaf; Oppenheimer, Clive; Guidobaldi, Giulia; Nievergelt, Daniel; et al. (30 June 2021). "Precise date for the Laacher See eruption synchronizes the Younger Dryas". Nature. 595 (7865): 66–69. Bibcode:2021Natur.595...66R. doi:10.1038/S41586-021-03608-X. ISSN1476-4687. WikidataQ107389873. [Measurements] firmly date the [Laacher See eruption] to 13,006 ± 9 calibrated years before present (BP; taken as AD 1950), which is more than a century earlier than previously accepted. ...thereby dating the onset of the Younger Dryas to 12,807 ± 12 calibrated years BP, which is around 130 years earlier than thought.