L’alcool contenu dans les boissons attaque les neurones de trois manières différentes. – Ph. via Pixabay / CC0 C’est la saison des apéritifs… Qui mettent de bonne humeur mais produisent également des réactions néfastes pour les cellules du cerveau. Jusqu’à les tuer ?
June 11, 2015: If you love stargazing, there's a date you need to mark on your calendar. It's June.
That's right, the whole month!
Throughout the month of June 2015, the two brightest planets in the night sky, Venus and Jupiter, are going to converge for a jaw-dropping close encounter. You don’t want to miss any of the action. Venus and Jupiter are converging for a must-see close encounter at...
June 26, 2015: It's funny, the things you notice hanging upside down in space. Astronaut John Mace Grunsfeld remembers a quirky discovery back in 1999. He had just arrived at the Hubble Space Telescope and climbed out of the airlock of Space Shuttle Discovery to begin a servicing mission. Clinging to a handrail running down the side of Hubble's gleaming exterior, he ran his eyes over the blue planet 350 miles below and tried not to think too hard about the yawning starry expanse behind him. The astronaut, Hubble, and Discovery, connected together, raced around Earth at 17,000...
June 26, 2015: Algae are complicated. The little plants can be both good and bad. Single-celled algae called phytoplankton are a main source of food for fish and other aquatic life, and account for half of the photosynthetic activity on Earth—that’s good. But certain varieties such as some cyanobacteria produce toxins that can harm humans, fish, and other animals. Under certain conditions, algae populations can grow explosively -- a spectacle known as an algal bloom, which can cover hundreds of square kilometers. For example, in August 2014, a cyanobacteria outbreak in...
في هذا الاستعراض الرائع لاهم النظريات حول منشأ الحياة يقدم لنا الدكتور سيبكوسكي، عالم المتحجرات، نظرة متكاملة علمية حول السؤال الذي لطالما شغل الناس. ونجد في هذا المقال عرضاً جميلاً وسلساً للأفكار العلمية في هذا الصدد، بعيداً عن اسطورة الخلق الدينية بمختلف نسخها...
كيف نشأت الحياة؟ بقلم ج . جون سيبكوسكي
تخيل معي انك قد هبطت على كوكب غريب، وبقعة هبوطك هي واحدة من الجزر البركانية...
قمت بترجمة هذا الموضوع ردّا على من يتشدّقون ببعض المعادلات الرياضّياتيّة التي لا يفهمونها من أجل تبيان أنّ الحياة يستحيل أن تنشأ من اللاحياة عن طريق التفاعلات الكيميائيّة، إنّه موضوع بسيط و ليس معقّدا.
الرياضّيات و حساب احتماليّة نشوء الحياة ( قانون بورل ). العنوان الأصليّ: Borel's Law and the Origin of Many Creationist Probability Assertions المترجم:...
This news release is reprinted courtesy of the European Space Agency, which is leading the Rosetta mission to Comet 67P. August 2, 2014: As the ESA's Rosetta spacecraft closes to within 1000 km of Comet 67P/Churyumov-Gerasimenko, the Rosetta science team has released a new image and made the first temperature measurements of the comet's core. The temperature data show that 67P is too hot to be covered in ice and must instead have a dark, dusty crust. The new image...
March 30, 2015: It's déjà vu all over again. For the third time in less than a year, sky watchers in the United States can see a total eclipse of the Moon. The action begins at 3:16 AM Pacific Daylight Time on the morning of April 4th when the edge of the Moon first enters the amber core of Earth’s shadow. For the next hour and 45 minutes, Earth's shadow will move across the lunar disk, ultimately swallowing the entire Moon at 4:58 AM PDT.
لو وضعت قدحا في قفص مغلق لايمكن رؤية ما بداخله ثم انهاريت عليه بالمضرب فببساطه لو اردت ان اعرف ان كان هذا القدح انكسر ام لا فيجب ان اراه هذا يعني بوضوح ان الحقيقه تتوقف علي انا وليس على الاله فلو كان القدح مكسورا فلن يحدد الله هذه الحقيقه بل انا من يحددها وان هنلك احتمالين اما ان يكون القدح غير مكسور وهو 1/2 او ان القدح مكسور وهو 1/2 ايضا بالنهايه فلو كان الاله موجودا وجب على القدح ان يعطي لااحد الاحتمالين قيمة 1 والاخر قيمة 0 وهذا يعني ان اي تاريخ او مستقبل لا يعتمد على الله بل يعتمد على الملاحظ...
Jan. 8, 2015: Scientists have paired NASA's Cassini spacecraft with the National Science Foundation's Very Long Baseline Array (VLBA) radio-telescope system to pinpoint the position of Saturn and its family of moons to within about 2 miles (4 kilometers). The measurement is some 50 times more precise than those provided by ground-based optical telescopes. The feat improves astronomers' knowledge of Saturn's orbit and benefits spacecraft navigation and basic physics research. The team of researchers used the VLBA -- a giant array of radio-telescope antennas spread from Hawaii...
Jan. 8, 2014: A new NASA satellite that will peer into the topmost layer of Earth's soils to measure the hidden waters that influence our weather and climate is in final preparations for a Jan. 29 dawn launch from California. The Soil Moisture Active Passive (SMAP) mission will take the pulse of a key measure of our water planet: how freshwater cycles over Earth's land surfaces in the form of soil moisture. The mission will produce the most accurate, highest-resolution global maps ever obtained from space of the moisture present in the top 2 inches (5 centimeters) of Earth's...
Jan. 5, 2014: Eta Carinae, the most luminous and massive stellar system within 10,000 light-years of Earth, is known for its surprising behavior, erupting twice in the 19th century for reasons scientists still don't understand. A long-term study led by astronomers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, used NASA satellites, ground-based telescopes and theoretical modeling to produce the most comprehensive picture of Eta Carinae to date. New findings include Hubble Space Telescope images that show decade-old shells of ionized gas racing away from the largest...
Feb 6, 2015: Water may be the most influential substance on Earth. It covers more than 70% of our planet's surface, plays a key role in weather and climate, and nurtures life itself. Earth's deep oceans are unique in the solar system, and their globe-spanning majesty, as seen from space, is a testament to the primacy of "H2O." Oceans, however, are just the most eye-catching repositories of water. The substance can be found in lesser amounts in almost every nook and cranny of the planet, and researchers know it is important to keep track of water everywhere. For example...
May 5, 2015: As May of 2015 unfolds, Halley's Comet is more than 5 billion kilometers from Earth, receding into the inky blackness of the outer solar system, where its looping orbit takes it every 76 years. Dim and distant, history's most famous comet won't be back until sometime in 2061. Can’t wait? You can see a piece of Halley's Comet this week. In early May, Earth passes through a stream of comet dust left behind by Halley many years ago. The encounter will cause a meteor shower called the “Eta Aquariids” visible from both hemispheres of Earth.
Jan. 6, 2015: How many stars like our sun host planets like our Earth? NASA’s Kepler Space Telescope continuously monitored more than 150,000 stars beyond our solar system, and to date has offered scientists an assortment of more than 4,000 candidate planets for further study -- the 1,000th of which was recently verified. Using Kepler data, scientists reached this millenary milestone after validating that eight more candidates spotted by the planet-hunting telescope are, in fact, planets. The Kepler team also has added another 554 candidates to the roll of potential planets,...
Jan. 5, 2015: The largest NASA Hubble Space Telescope image ever assembled, this sweeping bird’s-eye view of a portion of the Andromeda galaxy (M31) is the sharpest large composite image ever taken of our galactic next-door neighbor. This sweeping bird's-eye view of a portion of the Andromeda galaxy (M31) is the sharpest image ever...
Feb 5, 2015: Firing off a string of action snapshots like a sports photographer at a NASCAR race, NASA's Hubble Space Telescope captured the rare occurrence of three of Jupiter's largest moons racing across the banded face of the gas-giant planet: Europa, Callisto, and Io. These so-called Galilean moons, named after the 17th century scientist Galileo Galilei, who discovered them with a telescope, complete orbits around Jupiter with durations ranging from 2 days to 17 days. They can commonly be seen transiting the face of Jupiter and casting shadows onto its cloud tops. However,...
[size=24]لولا وجود الكتلة لما وجدت المادة ولولا وجود الكتلة لما وجدت الجاذبية الأرضية ولولا وجود الجاذبية الأرضية لما وجدت القوى،والقوى هي التي تُسبب كل أنواع الحركة، و القوى والحركة و الكتلة هي المتحكمة في وجودالمادة...
فكرة القدماء عن الزمن فكرة تقويمية ناتجة عن تعاقب الليل والنهار وتعاقب الفصول , وتَقدم مفهوم الزمن علمياً بالعلاقة بين الحركة والمسافة حيث كان تعريف الزمن بأنه الوقت المستغرق لحركة الجسم من مكان لآخر . وبقي الأمر على هذا الحال حتى مع نيوتن الذي إعتبر الزمن شئ مطلق يسري في كل أجزاء الكون بنفس المعدل , ومن هنا أتى مفهوم التزامن حيث إن ما يحدث هنا في هذا الوقت يمكن أن يحدث في كل أجزاء الكون بنفس الوقت . هذا المفهوم عن الزمن أُلغي في نسبية آينشتاين , إذ لم يعد الزمن مطلقاً إنما أصبح...
1-توماس إديسون هو مخترع المصباح الكهربائي هناك الكثير من العلماء والمخترعين قد عملوا على اختراع المصباح بسنوات عدة قبل أن يبدأ توماس إديسون في تجاربه، وترجع المحاولة الأولى لصنع المصباح الكهربائي إلى عام 1802 عندما تمكن رجل يدعى هامفري ديفي من الحصول على ضوء قصير الأجل عن طريق تمرير تيار كهربائي من خلال خيط رفيع من البلاتينيوم. وقد تلت ذلك محاولات عديدة أصبحت لا تُذكر لتنتهي إلى انتساب الفضل وحده تقريباً لتوماس إديسون.
2-صفقة روزفلت هي التي أنهت الكساد العظيم في أميركا وتعود صفقة روزفلت على مجموعة...
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اليوم في 1:55 pm من طرف