Star Formation Extinguished by Quasars

According to new research, a galaxy with a quasar in the middle is not a good place to grow up. As active galactic nuclei (AGN) evolve, they pass through a "quasar phase", where the accretion disk surrounding the central black hole blasts intense radiation into space. The quasar far outshines the entire host galaxy. After the quasar phase, when the party is over, it is as if there is no energy left and star formation stops.

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13.73 میلیارد سال - دقیق ترین سن اندازه گیری شده برای جهان

بررسی ناهمسانگردی میکروموج ویکینسون سازمان ناسا ( WMAP ) ، بهترین اندازه گیری در مورد سن جهان تا کنون را ارائه کرد. با رصد بسیار دقیق تابش میکروموج ساطع شده از سراسر کیهان ، دانشمندان  WMAP بهترین تخمین در مورد سن جهان را 13.73 میلیارد سال به اضافه و منهای 120 میلیون سال ( که این میزان خطا یعنی 0.87 %  به واقع بد نیست ) اعلام کردند.

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13.73 Billion Years - The Most Precise Measurement of the Age of the Universe Yet

NASA's Wilkinson Microwave Anisotropy Probe (WMAP) has taken the best measurement of the age of the Universe to date. According to highly precise observations of microwave radiation observed all over the cosmos, WMAP scientists now have the best estimate yet on the age of the Universe: 13.73 billion years, plus or minus 120 million years (that's an error margin of only 0.87%… not bad really…).

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Explaining Dark Matter and Contradicting the Big Bang

It’s well-known that “Big Bang” was a derogatory name given to the cosmological theory of the expanding (not exploding) universe in an attempt to discredit the idea. But, the name stuck and with the discovery of the cosmic microwave background (CMB) in 1964, the theory has stuck, too. However, every once in awhile, a new idea comes out which claims to contradict the Big Bang Theory. The latest comes from researchers Robert K. Soberman and Maurice Dubin who say they know what dark matter is comprised of, and their new ideas provide a better explanation for the CMB, as well as the galactic red shift, two observations that currently support the Big Bang Theory.

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Why There's More Matter Than Antimatter in the Universe

In the first few moments of the Universe, enormous amounts of both matter and antimatter were created, and then moments later combined and annihilated generating the energy that drove the expansion of the Universe. But for some reason, there was an infinitesimal amount more matter than antimatter. Everything that we see today was that tiny fraction of matter that remained.

But why? Why was there more matter than antimatter right after the Big Bang? Researchers from the University of Melbourne think they might have an insight.

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Time Traveling With Spitzer

While time travel is seemingly impossible, we can actually look back in time with our telescopes to learn about the conditions of our universe in times past. The Spitzer Space Telescope has found some very dim and distant galaxies located at the edge of our universe that have never been seen before. Approximately 12.5 billion light-years away from Earth, we’re seeing these galaxies as when our universe was just one billion years old. With Spitzer's infrared capability, astronomers have been able to take infrared portraits and even "weigh" many of these early galaxies. "Understanding the mass and chemical makeup of the universe's first galaxies and then taking snapshots of galaxies at different ages, gives us a better idea of how gas, dust and metals– the material that went into making our Sun, solar system, and Earth –has changed throughout the Universe's history," said Spitzer scientist Dr. Ranga Ram Chary.

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Could Cosmic Rays Influence Global Warming?

The idea goes like this: Cosmic rays, originating from outside the Solar System, hit the Earth's atmosphere. In doing so these highly energetic particles create microscopic aerosols. Aerosols collect in the atmosphere and act as nuclei for water droplet formation. Large-scale cloud cover can result from this microscopic interaction. Cloud cover reflects light from the Sun, therefore cooling the Earth. This "global dimming" effect could hold some answers to the global warming debate as it influences the amount of radiation entering the atmosphere. Therefore the flux of cosmic rays is highly dependent on the Sun's magnetic field that varies over the 11-year solar cycle.

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When Black Holes Explode: Measuring the Emission from the Fifth Dimension

Primordial black holes are remnants of the Big Bang and they are predicted to be knocking around in our universe right now. If they were 10¹²kg or bigger at the time of creation, they have enough mass to have survived constant evaporation from Hawking radiation over the 14 billion years since the beginning of the cosmos. But what happens when the tiny black hole evaporates so small that it becomes so tightly wrapped around the structure of a fifth dimension (other than the "normal" three spatial dimensions and one time dimension)? Well, the black hole will explosively show itself, much like an elastic band snapping, emitting energy. These final moments will signify that the primordial black hole has died. What makes this exciting is that researchers believe they can detect these events as spikes of radio wave emissions and the hunt has already begun…

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Planets Might Actually Shape Planetary Nebulae (plus a gallery)

Despite the name, a "planetary nebula" has nothing to do with planets. They were given the confusing name 300 years ago by William Herschel because they looked like planets in their early, rudimentary telescopes. They're really the glowing shells of gas and dust puffed out by stars nearing the end of their lives. But wait, planets might be responsible after all.

And as a special bonus for actually reading this article, I'll treat you to a gallery of beautiful planetary nebulae.

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What Happens When Supermassive Black Holes Collide?

As galaxies merge together, you might be wondering what happens with the supermassive black holes that lurk at their centres. Just imagine the forces unleashed as two black holes with hundreds of millions of times the mass of the Sun come together. The answer will surprise you. Fortunately, it's an event that we should be able to detect from here on Earth, if we know what we're looking for.

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What Would Happen if a Small Black Hole Hit the Earth?

We can all guess what would happen should a massive black hole drift into our solar system… there wouldn't be much left once the intense gravitational pull consumes the planets and starts sucking away at our Sun. But what if the black hole is small, perhaps a left over remnant from the Big Bang, passing unnoticed through our neighborhood, having no observable impact on local space? What if this small singularity falls in the path of Earths orbit and hits our planet? This strange event has been pondered by theoretical physicists, understanding how a small black hole could be detected as it punches a neat hole though the Earth…

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"Listening" for Gravitational Waves to Track Down Black Holes

Gravitational waves are predicted by Einstein's 1916 general theory of relativity, but they are notoriously hard to detect and it's taken many decades to come close to observing them. Now, with the help of a supercomputer named SUGAR (Syracuse University Gravitational and Relativity Cluster), two years of data collected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) will be analyzed to find gravitational waves. Once detected, it is hoped that the location of some of the Universes most powerful collisions and explosions will be found, perhaps even hearing the distant ringing of celestial black holes…

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Large Hadron Collider May Help Us Glimpse Into another Dimension

High energy collisions by the nearly-completed Large Hadron Collider (LHC) may be able to generate particles that are sensitive to dimensions beyond our four dimensional space-time. These exotic particles, called Kaluza-Klein gravitons, would be highly sensitive to the geometry of extra-dimensions, giving scientists an idea about what lies beyond our universe. If these particles are detected, and if their characteristics can be measured, then perhaps the extra dimensions predicted by string theory may be proven to exist…

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Red Dwarfs Have Teeny Tiny Habitable Zones

As space telescopes get larger and more sensitive, the search for Earth-sized worlds surrounding other stars is about to get rolling. But astronomers are going to need to know where to look. A team of researchers are working on a survey of nearby stars, calculating the habitable zones around them. When the search begins, astronomers are going to want to study these regions.

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Shedding light on dark energy

AMUNDSEN-SCOTT STATION, Antarctica -- Anywhere else it would be a big telescope, as high as a 7-story building, with a main mirror measuring 32 feet wide. But at the South Pole, it seems especially large, looming over a barren plain of ice that gets colder than anywhere else on the planet.

Scientists built the instrument at the end of the world to search for clues that might identify the most powerful, plentiful but elusive substance in the universe -- dark energy.

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آزمایش میون ها

در طی سالها تلاشهای بسیاری برای مشاهده انبساط زمان انجام شده است.به عنوان مثال یکی از ایده ها جاسازی یک ساعت اتمی در هواپیمایی پر سرعت و نگه داشتن آن در آسمان به مدت کافی بود ، تا هنگامی که هواپیما به زمین مراجعت کرد و ساعت هواپیما با ساعت ساکن روی زمین مقایسه شد،اثر انبساط زمان دیده شود.(این آزمایش در ایستگاه فضایی انجام شده است.) اما نتیجه جالب توجه در مدت زمان طولانی بدست می آید.هنگامیکه بتوان پارادوکس دوقلو ها را اجرا کرد.

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Did Einstein Predict Dark Energy?

Oddly enough, dark energy — for all the surprise around its discovery — is not an entirely new concept in physics. There is historical background for this idea, and it comes from the preeminent astronomer of the 20^th century, Albert Einstein.

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شناسايي کهکشان هاي پنهان

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Universe May Be Running Out of Time

With heat death, the big crunch and quite a few other nasty ways in which the universe could see its demise, we can now add "running out of time" to the list. A team of scientists came up with a new theory that would solve the problem of the elusive dark energy that seems to be accelerating the expansion of the universe. They figure that the universe is not speeding up but we are, in relation to the outer regions of space, slowing down. Tests with the upcoming Large Hadron Collider will give more insight if we're going to end up frozen in time."

Supercomputers Pitch in to Search for Missing Matter

 I know, I know, you're probably getting sick of hearing this. Astronomers have no idea what 95% of the Universe is; 70% is dark energy, and 25% is dark matter, leaving a mere 5% normal matter. But it gets worse. Astronomers can only actually account for about 60% of that regular matter (hydrogen, helium and heavier elements) - almost half of the regular matter is missing too!

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Has Dark Energy Always Been Constant?

Dark energy is that mysterious force that seems to be accelerating the expansion of the Universe. But the question is: has it always been pushing the Universe apart with the same force, or was it weaker or stronger in the past, and will it get stronger in the future? Researchers from the Harvard-Smithsonian Center for Astrophysics have a plan to study distant clumps of hydrogen, to get to the bottom of this question, once and for all.

كهكشانها

کهکشان مجموعه ایست از ستارگان، غبار و گاز که توسط گرانش در کنار یکدیگر قرار گرفته اند. منظومه شمسی ما در کهکشانی به نام راه شیری قرار گرفته است. دانشمندان تخمین می زنند که بیش از 100 بیلیون کهکشان در فضای مرئی کائنات پراکنده شده اند. ستاره شناسان به کمک تلسکوپ از میلیونها کهکشان تصویر گرفته اند. دورترین کهکشانهایی که تا کنون عکس آنها تهیه شده است، در فاصله 10 تا 13 بیلیون سال نوری از ما قرار گرفته اند. قطر کهکشانها از چند هزار تا نیم میلیون سال نوریست. کهکشانهای کوچکتر کمتر از یک بیلیون ستاره دارند اما کهکشانهای بزرگ دارای بیش از یک تریلیون ستاره هستند. قطر کهکشان راه شیری حدود 100.000 هزار سال نوریست. منظومه شمسی در فاصله 25.000 سال نوری از مرکز کهکشان قرار گرفته است. حدود 100 بیلیون ستاره در این کهکشان وجود دارد.

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جست‌وجوي اجرامي شگفت انگيزتر از سياهچاله‌ها

دانشمندان وجود دسته‌اي جديد از سياهچاله‌ها را پيش بيني کرده‌اند که به دليل سرعت بسيار زياد چرخش به دور خود افق رويداد ندارند.

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ادغام کهکشان و يکي شدن سياهچاله ها

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Hubble Sees Ancient Galactic Building Blocks

Let's go back, way back, to an earlier time when the Universe was a fraction of its current age. Tiny galaxies, just a fraction of the mass of the Milky Way came together, piece by piece, building up larger and larger galaxies. Well, we don't have a time machine, but we've got the next best things: Hubble and Spitzer, which were called upon to look back into the distant Universe, to watch this process unfold.

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تاکیون ها

مارس 1993 بوسيله ي اسكات . آي. چيس (Scott I. Chase) اولين انتشار در مجله ي علوم (Science Magazine) رجينالد بولر: (Reginald Buller): روزي يك خانم كه نامش روشن بود با سرعت بسيار بيشتر از نور وارد راه نسبيت شد و شب گذشته برگشت! اين براي همه مشخص است كه سفر با سرعتي بالاتر از نور امكان ندارد. در بهترين حالت يك ذره ي بدون جرم با سرعت نور سفر مي كند. اما آيا اين درست است؟

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کشف مقادير عظيم آب در اطراف يک پيش ستاره

در تحقيقي که گروهي از دانشمندان با استفاده از تلسکوپ فضايي «اسپيتزر» انجام دادند، موفق شدند مقادير زيادي آب در اطراف يک پيش ستاره کشف کنند.

به گزارش سرويس علمي خبرگزاري دانشجويان ايران(ايسنا)، در اين تحقيق دانشمنداني از دانشگاه «روچستر» (Rochester) موفق به کشف مقدار زيادي بخار آب در اطراف پيش ستاره‌اي به نام NGC 1333-IRAS 4B شدند.

مقدار آب يافت شده در حوالي اين پيش ستاره به قدري زياد است که با آن مي‌توان پنج بار تمام درياها و اقيانوس‌هاي زمين را از آب پر کرد. . .

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هاوكينگ: علم بايد همانند داستانهاي علمي تخيلي هيجان انگيز باشد

به گزارش خبرگزاري فرانسه از كمبريج، استاد دانشگاه كمبريج گفت از آنجا كه كودكان از ذهن باز و شوق يادگيري برخوردارند توضيح مسائل براي آنها آسانتر است.

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نتايج يك تحقيق/ گرانش دافعه‌اي مي‌تواند منشا انرژي تاريك كيهاني باشد

آقاي "شانت باغرام" روز يكشنبه در گفت ‌وگو با خبرنگار ايرنا گفت، مشاهدات اخير كيهان شناسي مانند رصد ابرنواختر نوع ‪ I‬نشان مي‌دهد كيهان در حال حاضر در يك فاز شتاب تندشونده قرار دارد و ساير مشاهدات مانند تابش پس زمينه كيهاني نيز حاكي از تخت بودن عالم است.

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دماي ستارگان

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