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A board for scientific/technological discussion and the distribution of knowledge!


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Sulfur selenium battery Anonymous 10/23/2023 (Mon) 00:30 [Preview] No. 58 [Reply] [Last 50 Posts]
NASA says its sulfur selenium prototype battery has an energy density of 500 watt-hours per kilogram, which is about double that of conventional lithium-ion batteries.

https://www.nasa.gov/aeronautics/nasas-solid-state-battery-research-exceeds-initial-goals-draws-interest/


Anonymous 10/23/2023 (Mon) 00:44 [Preview] No.59 del
https://youtube.com/watch?v=hG3m9Rk86YM [Embed]


Anonymous 10/26/2023 (Thu) 05:10 [Preview] No.68 del
https://youtube.com/watch?v=50m6bYf7aY4 [Embed]



Chime IbbyTbby 10/24/2023 (Tue) 05:13 [Preview] No. 67 [Reply] [Last 50 Posts]
Someone scammed me on Chime. Any way to get my money back?





Anonymous 10/23/2023 (Mon) 03:17 [Preview] No.62 del
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Natural gas


Anonymous 10/23/2023 (Mon) 03:18 [Preview] No.63 del
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Coal


Anonymous 10/23/2023 (Mon) 03:19 [Preview] No.64 del
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Electricity


Anonymous 10/23/2023 (Mon) 03:20 [Preview] No.65 del
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Renewable energy


Anonymous 10/23/2023 (Mon) 03:20 [Preview] No.66 del
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Key minerals



Grid Compass 1101 Anonymous 10/04/2023 (Wed) 23:19 [Preview] No. 56 [Reply] [Last 50 Posts]
Первый ноутбук Человечества. Был разработан в 1982 году.

Корпус-раскладушка изготовлен из магниевого сплава. Процессор Intel 8086, математический сопроцессор Intel 8087, 256-килобайтной (до 512 КБ) оперативной памятью, электролюминесцентным дисплеем разрешением 320 × 240, 340-килобайтной пузырьковой памятью и модемом 1200 бит/с. Устройства, такие как жёсткий диск и дисковод, могли быть подключены при помощи порта IEEE-488 I/O.

Ноутбук весил 5 кг. Питался от ~110/220 Вольт переменного тока, 47-66 Гц, 75 Ватт.

На Grid Compass была установлена собственная операционная система GRiD O/S.


Anonymous 10/04/2023 (Wed) 23:20 [Preview] No.57 del
GRiD Compass 1101 был первым ноутбуком в космосе для этого его пришлось модифицировать и впервые добавить вентилятор для вытягивания воздуха из корпуса.



New Post-DART Collision Period for the Didymos System: Evidence for Anomalous Orbital Decay Anonymous 09/14/2023 (Thu) 23:08 [Preview] No. 53 [Reply] [Last 50 Posts]
On September 26, 2022, NASA's DART spacecraft impacted Dimorphos, the secondary asteroid in the (65803) Didymos system, so that the efficiency with which a satellite could divert an asteroid could be measured from the change in the system's period. We present new data from the Thacher Observatory and measure a change in period, ΔP=−34.2±0.1 min, which deviates from previous measurements by 3.5σ. This suggests that the system period may have decreased by ∼1 minute in the 20 to 30 days between previous measurements and our measurements. We find that no mechanism previously presented for this system can account for this large of a period change, and drag from impact ejecta is an unlikely explanation. Further observations of the (65803) Didymos system are needed to both confirm our result and to further understand this system post impact.

https://arxiv.org/pdf/2308.15488.pdf



Binary-star study favours modified gravity over dark matter Anonymous 08/21/2023 (Mon) 01:33 [Preview] No. 45 [Reply] [Last 50 Posts]
A new study of data from the European Space Agency’s Gaia space mission claims to have found evidence of gravity acting contrary to the predictions of Newton and Einstein, but not everyone agrees that this is the smoking gun for a theory of modified gravity.

Observations of galaxies and galaxy clusters show that the gravitational forces binding these structures together are greater than those expected from the matter they contain. This has led physicists to predict the existence of dark matter, which is a hypothetical material that is invisible but interacts with normal matter via gravity. While dark matter has never been observed directly, it is included in the standard model of cosmology.

Modified Newtonian dynamics, or MOND for short, was developed in 1983 by Mordehai Milgrom of the Weizmann Institute in Israel as an alternative to models of dark matter. MOND seeks to explain the apparent extra gravity binding together galaxies and galaxy clusters by modifying the physics of gravity. In particular, MOND describes how gravity operates differently at very low accelerations.

Despite occasional successes for MOND, such as describing the motion of stars around galaxies, the evolution of open star clusters, and the survival of dwarf galaxies, MOND is not seen as a mainstream model. However, supporters of MOND point out that dark matter has yet to be observed directly, and that dark-matter models are everchanging as their predictions are excluded by experiments and observations. Proponents of dark matter, on the other hand, argue that MOND cannot yet explain many of the things that dark matter models can.

Stars separated by large distances in binary systems have long been considered objects that could put MOND to the test. This is because accelerations in such “wide binaries” are small enough that MOND is relevant, but dark matter is not expected to affect such systems.

Now, with Data Release 3 (DR3) from the Gaia astrometric mission, astronomers finally have the data to put MOND to the test in these binary systems. In a new paper published in The Astrophysical Journal, Kyu-Hyun Chae of Sejong University in South Korea has used statistics to analyse data describing the orbital motions of 26,500 wide-binary star systems, all located within 650­­­­ light– years of Earth. In particular, Chae calculated the gravitational accelerations of the stars around one another.

“A binary system is gravitationally bound, so it always experiences an internal gravitational acceleration in its orbit,” Chae tells Physics World.

If the stars had perfectly circular orbits around one another, their gravitational acceleration would remain constant. In reality, they have elliptical orbits, meaning that their separation from one another and hence their gravitational acceleration changes. The binary stars in the study can range in separation from between 200 AU to 30,000 AU – where 1 AU is the distance from the Earth to the Sun.

The measured gravitational acceleration is exceptionally tiny. At separations of less than 1000 AU, the gravitational acceleration is greater than 10 nm/s2 and gravity is observed to act as predicted by Newtonian physics. However, at separations of more than 2000 AU, where the gravitational acceleration is on the order of 1 nm/s2, Chae says that his analysis reveals discrepancies in the acceleration, with its value being greater than what the models of Newton and Einstein predict. At more than 5000 AU, where the gravitational acceleration is less than 0.1 nm/s2, the difference is clearly seen.

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Anonymous 08/21/2023 (Mon) 01:33 [Preview] No.46 del
Furthermore, Chae says that when one takes into account the external field effect – an integral part of MOND that describes how a much larger gravitational field, in this case that of the Milky Way galaxy as a whole, can affect a smaller gravitational system such as a binary star – the gravitational acceleration at wide separations is boosted by a factor of 1.4. This matches a prediction of a specific model of MOND called AQUAL, which was developed by Milgrom and the late physicist Jacob Bekenstein of the Hebrew University of Jerusalem..

“It is truly remarkable that when the external field effect is taken into account, the boost factor is about 1.4,” says Chae. “To me, this cannot be a coincidence.”


Anonymous 08/21/2023 (Mon) 01:35 [Preview] No.47 del
Smoking-gun evidence for modified gravity at low acceleration from Gaia observations of wide binary stars

A new study reports conclusive evidence for the breakdown of standard gravity in the low acceleration limit from a verifiable analysis of the orbital motions of long-period, widely separated, binary stars, usually referred to as wide binaries in astronomy and astrophysics.

The study carried out by Kyu-Hyun Chae, professor of physics and astronomy at Sejong University in Seoul, used up to 26,500 wide binaries within 650 light years (LY) observed by European Space Agency's Gaia space telescope. The study was published in the 1 August 2023 issue of the Astrophysical Journal.

For a key improvement over other studies Chae's study focused on calculating gravitational accelerations experienced by binary stars as a function of their separation or, equivalently the orbital period, by a Monte Carlo deprojection of observed sky-projected motions to the three-dimensional space.

Chae explains, "From the start it seemed clear to me that gravity could be most directly and efficiently tested by calculating accelerations because gravitational field itself is an acceleration. My recent research experiences with galactic rotation curves led me to this idea. Galactic disks and wide binaries share some similarity in their orbits, though wide binaries follow highly elongated orbits while hydrogen gas particles in a galactic disk follow nearly circular orbits."

Also, unlike other studies Chae calibrated the occurrence rate of hidden nested inner binaries at a benchmark acceleration.

The study finds that when two stars orbit around with each other with accelerations lower than about one nanometer per second squared start to deviate from the prediction by Newton's universal law of gravitation and Einstein's general relativity.

For accelerations lower than about 0.1 nanometer per second squared, the observed acceleration is about 30 to 40% higher than the Newton-Einstein prediction. The significance is very high meeting the conventional criteria of 5 sigma for a scientific discovery. In a sample of 20,000 wide binaries within a distance limit of 650 LY two independent acceleration bins respectively show deviations of over 5 sigma significance in the same direction.

Because the observed accelerations stronger than about 10 nanometer per second squared agree well with the Newton-Einstein prediction from the same analysis, the observed boost of accelerations at lower accelerations is a mystery. What is intriguing is that this breakdown of the Newton-Einstein theory at accelerations weaker than about one nanometer per second squared was suggested 40 years ago by theoretical physicist Mordehai Milgrom at the Weizmann Institute in Israel in a new theoretical framework called modified Newtonian dynamics (MOND) or Milgromian dynamics in current usage.

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Anonymous 08/21/2023 (Mon) 01:36 [Preview] No.48 del
>>47
Unlike galactic rotation curves in which the observed boosted accelerations can, in principle, be attributed to dark matter in the Newton-Einstein standard gravity, wide binary dynamics cannot be affected by it even if it existed. The standard gravity simply breaks down in the weak acceleration limit in accordance with the MOND framework.

Implications of wide binary dynamics are profound in astrophysics, theoretical physics, and cosmology. Anomalies in Mercury's orbits observed in the nineteenth century eventually led to Einstein's general relativity.

Now anomalies in wide binaries require a new theory extending general relativity to the low acceleration MOND limit

https://phys.org/news/2023-08-smoking-gun-evidence-gravity-gaia-wide.html


Anonymous 08/21/2023 (Mon) 02:03 [Preview] No.49 del
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Традиционное понимание гравитации, сформировавшееся благодаря работам Ньютона и Эйнштейна, подвергается проверке новыми наблюдениями. Используя данные космической обсерватории Gaia, профессор Кю-Хюн Чэ изучил движение тысяч бинарных звезд. Полученные им результаты свидетельствуют о поведении, противоречащем устоявшимся гравитационным теориям, даже теориям темной материи и темной энергии. Если эти результаты подтвердятся, то они могут пересмотреть наши представления о силах, структурирующих Вселенную. Гравитация - фундаментальная сила, управляющая движением небесных тел, — уже давно определена в работах Ньютона и Эйнштейна. Однако в век космических телескопов и передовых технологий наши традиционные представления подвергаются испытанию. Недавнее исследование профессора Кю-Хюн Чэ из Университета Седжонг поставило под сомнение наше понимание гравитации. Проанализировав динамику 26 500 крупных бинарных звезд с помощью данных космической обсерватории Gaia Европейского космического агентства, Чэ выявил аномалии в орбитальных движениях звезд. Эти аномалии свидетельствуют о том, что законы гравитации Ньютона и Эйнштейна могут быть неприменимы в условиях малых ускорений. Эти открытия могут пересмотреть наши представления о силах, структурирующих Вселенную, и подтвердить новую теорию гравитации.

https://new-science.ru/gravitaciya-po-novomu-vyzov-teoriyam-njutona-i-ejnshtejna/


Anonymous 09/09/2023 (Sat) 05:34 [Preview] No.51 del
и тишина...



Anonymous 08/21/2023 (Mon) 02:28 [Preview] No. 50 [Reply] [Last 50 Posts]
Conclusive Evidence for Modified Gravity: Collapse of Newton’s and Einstein’s Theories in Low Acceleration

Dawn of a new scientific revolution

https://scitechdaily.com/conclusive-evidence-for-modified-gravity-collapse-of-newtons-and-einsteins-theories-in-low-acceleration/



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Anonymous 08/18/2023 (Fri) 11:47 [Preview] No. 42 [Reply] [Last 50 Posts]
WTF?


Anonymous 08/18/2023 (Fri) 14:33 [Preview] No.43 del
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bump


Anonymous 08/18/2023 (Fri) 14:37 [Preview] No.44 del



Astronomers scan 11,680 nearby stars for signals from advanced civilizations Anonymous 08/17/2023 (Thu) 23:53 [Preview] No. 41 [Reply] [Last 50 Posts]
The Green Bank Telescope captured emissions from around 11,680 stars and their planetary systems that lay between 5,385 and 18,173 light-years away. The observations occurred during two-hour sessions on April 22, 202, April 28, 2021, May 22, 2022, and May 13, 2023. They did two scans of about 2.5 minutes each on selected pairs of sources. Then, they processed the data, which included about 37 million narrowband detections of emissions. The resulting conclusion was that there are no advanced civilizations nearby that are transmitting in that range of frequencies.

https://phys.org/news/2023-08-astronomers-scan-nearby-stars-advanced.html



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матёша Anonymous 08/17/2023 (Thu) 06:16 [Preview] No. 40 [Reply] [Last 50 Posts]
Как получается что (1+x)^2 = 1+2x+x^2 ?