Formation of organic molecules & “Prebiotic chemistry”

“Prebiotic chemistry” can be understood to mean various things: chemistry which occurred before life began or the chemistry which led to life on Earth, and possibly on other planets. Workers in the field practically define it as naturally occurring, mainly organic, chemistry in planetary or other solar system environments, which may have contributed to the origin of life on Earth, or elsewhere. The terms “abiotic chemistry” (chemistry which takes place in the absence of biology) and “prebiotic chemistry” are in some senses synonymous. Since it is generally assumed that the universe is not goal directed, and since it is not known what processes led to the origin of life, the study of prebiotic chemistry almost certainly includes both productive and nonproductive chemical processes. This review places this chemistry in a historical and cosmic context and details some of the known reactions thought to be important. However, the interested reader is referred to more technical texts (Miller and Orgel 1974; Cleaves 2008; Cleaves and Lazcano 2009) and references therein.
How life on Earth began remains an unexplained scientific problem. This problem is nuanced in its practical details and the way attempted explanations feedback with questions and developments in other areas of science, including astronomy, biology, and planetary science. Prebiotic chemistry attempts to address this issue theoretically, experimentally, and observationally. The ease of formation of bioorganic compounds under plausible prebiotic conditions suggests that these molecules were present in the primitive terrestrial environment. In addition to synthesis in the Earth's primordial atmosphere and oceans, it is likely that the in fill of comets, meteorites, and interplanetary dust particles, as well as submarine hydrothermal vent synthesis, may have contributed to prebiotic organic evolution. The primordial organic soup may have been quite complex, but it did not likely include all of the compounds found in modern organisms. Regardless of their origin, organic compounds would need to be concentrated and complexified by environmental mechanisms.
"Scientists from Japan and the U.S. have confirmed the presence in meteorites of a key organic molecule which may have been used to build other organic molecules, including some used by life. The discovery validates theories of the formation of organic compounds in extraterrestrial environments.

The chemistry of life runs on organic compounds, molecules containing carbon and hydrogen, which also may include oxygen, nitrogen and other elements. While commonly associated with life, organic molecules also can be created by non-biological processes and are not necessarily indicators of life. An enduring mystery regarding the origin of life is how biology could have arisen from non-biological chemical processes, called prebiotic chemistry. Organic molecules from meteorites are one of the sources of organic compounds that lead to the formation of life on Earth."

"An international team of researchers has detected a poly heterocyclic organic molecule called hexamethylenetetramine in three carbonaceous meteorites: Murchison, Murray, and Tagish Lake. The presence of this molecule in carbon-rich meteorites promises its pivotal role to carry interstellar prebiotic precursors to the inner Solar System, which should contribute to the chemical evolution in the primordial stage on Earth.

Presence of organic molecules in extraterrestrial environments has been widely accepted thanks to recent successes in the detection of cometary molecules toward comet 67P/Churyumov-Gerasimenko, as well as long-standing astronomical observations and analyses of carbonaceous meteorites in laboratories.

However, despite extensive studies on the formation of organic molecules in various extraterrestrial environments such as molecular clouds, protosolar nebula and asteroids, it still remains under debate when, where, and how such extraterrestrial molecules were formed."

Thanks

Robert Stonjek, https://evolution-outreach.biomedcentral.com/articles/10.1007/s12052-012-0443-9

Cosmic Triangles Open a Window to the Origin of Time

Cecile G. Tamura

A close look at fundamental symmetries has exposed hidden patterns in the universe. Physicists think that those same symmetries may also reveal time’s original secret.

The Cosmological Bootstrap: Inflationary Correlators from Symmetries and Singularities

(https://www.quantamagazine.org/the-origin-of-time-bootstrapped-from-fundamental-symmetries-20191029/?fbclid=IwAR3Ty4_RN5CpbSXTVHdRaGRvs2HEltqypC3FKPNEu6qjR6jDu49w6WWSUAw)

“We look at patterns in space today, and we infer a cosmological history in order to explain them.

The approach has the potential to help explain why time began, and why it might end.

As Arkani-Hamed put it, “The thing that we’re bootstrapping is time itself.”

"One curious pattern cosmologists have known about for decades is that space is filled with correlated pairs of objects: pairs of hot spots seen in telescopes’ maps of the early universe; pairs of galaxies or of galaxy clusters or superclusters in the universe today; pairs found at all distances apart.

You can see these “two-point correlations” by moving a ruler all over a map of the sky. When there’s an object at one end, cosmologists find that this ups the chance that an object also lies at the other end."

"The simplest explanation for the correlations traces them to pairs of quantum particles that fluctuated into existence as space exponentially expanded at the start of the Big Bang. Pairs of particles that arose early on subsequently moved the farthest apart, yielding pairs of objects far away from each other in the sky today. Particle pairs that arose later separated less and now form closer-together pairs of objects. Like fossils, the pairwise correlations seen throughout the sky encode the passage of time — in this case, the very beginning of time."

A Map of the Start of Time

In 1980, the cosmologist Alan Guth, pondering a number of cosmological features, posited that the Big Bang began with a sudden burst of exponential expansion, known as “cosmic inflation.” Two years later, many of the world’s leading cosmologists gathered in Cambridge, England, to iron out the details of the new theory. Over the course of the three-week Nuffield workshop, a group that included Guth, Stephen Hawking, and Martin Rees, the future Astronomer Royal, pieced together the effects of a brief inflationary period at the start of time. By the end of the workshop, several attendees had separately calculated that quantum jitter during cosmic inflation could indeed have happened at the right rate and evolved in the right way to yield the universe’s observed density variations.

To understand how, picture the hypothetical energy field that drove cosmic inflation, known as the “inflaton field.” As this field of energy powered the exponential expansion of space, pairs of particles would have spontaneously arisen in the field. (These quantum particles can also be thought of as ripples in the quantum field.) Such pairs pop up in quantum fields all the time, momentarily borrowing energy from the field as allowed by Heisenberg’s uncertainty principle. Normally, the ripples quickly annihilate and disappear, returning the energy. But this couldn’t happen during inflation. As space inflated, the ripples stretched like taffy and were yanked apart, and so they became “frozen” into the field as twin peaks in its density. As the process continued, the peaks formed a nested pattern on all scales.

After inflation ended (a split second after it began), the spatial density variations remained. Studies of the ancient light called the cosmic microwave background have found that the infant universe was dappled with density differences of about one part in 10,000 — not much, but enough. Over the nearly 13.8 billion years since then, gravity has heightened the contrast by pulling matter toward the dense spots: Now, galaxies like the Milky Way and Andromeda are 1 million times denser than the cosmic average. As Guth wrote in his memoir (referring to a giant swath of galaxies rather than the wall in China), “The same Heisenberg uncertainty principle that governs the behavior of electrons and quarks may also be responsible for Andromeda and The Great Wall!”

What is the No-Boundary Proposal

Cecile G. Tamura

Stephen Hawking had a vision that the universe expanded out of a dimensionless point, rather like a shuttlecock. Recently, his stunning proposal has come under attack, but a vigorous defense has been mounted.

“If you know the wave function of the universe, why aren’t you rich?” — Murray Gell-Mann

 " The “no-boundary proposal,” which Hawking and his frequent collaborator, James Hartle, fully formulated in a 1983 paper, envisions the cosmos having the shape of a shuttlecock. Just as a shuttlecock has a diameter of zero at its bottommost point and gradually widens on the way up, the universe, according to the no-boundary proposal, smoothly expanded from a point of zero size. Hartle and Hawking derived a formula describing the whole shuttlecock — the so-called “wave function of the universe” that encompasses the entire past, present and future at once — making moot all contemplation of seeds of creation, a creator, or any transition from a time before.

Hartle and Hawking’s proposal radically reconceptualized time. Each moment in the universe becomes a cross-section of the shuttlecock; while we perceive the universe as expanding and evolving from one moment to the next, time really consists of correlations between the universe’s size in each cross-section and other properties — particularly its entropy, or disorder. Entropy increases from the cork to the feathers, aiming an emergent arrow of time. Near the shuttlecock’s rounded-off bottom, though, the correlations are less reliable; time ceases to exist and is replaced by pure space. As Hartle, now 79 and a professor at the University of California, Santa Barbara, explained it by phone recently, “We didn’t have birds in the very early universe; we have birds later on. … We didn’t have time in the early universe, but we have time later on.”

நம் பால்வழிமண்டலம்

Mohana Somasundram

சூரியனை நமது பூமி 365.25 நாளில் சுற்றி வருகிறது.சூரியன் நொடிக்கு 220 கி.மீ வேகத்தில் பால்வழி மண்டலத்தை சுற்றுகிறது. இந்த வேகத்தில் சுற்றினால் ஒரு முறை பால்வழிமண்டலத்தை நம் சூரியன், அவரது குடும்பத்தின் குஞசு,குளுவானையும் (சூரிய குடும்ப உறுப்பினர்களான, கோள்கள், துணைக்கோள்கள் ,அஸ்டிராயிடு , குயூப்பியார் வளையம் மற்றும் ஊர்ட் மேகம் இவற்றையும் இழுத்துக்கொண்டு ஒரு முறை சுற்றி முடிக்க, 24 கோடி ஆண்டுகள் ஆகின்றன.இதனைத்தான் பிரபஞச ஆண்டு (cosmic year ) அம்மாடியோவ்..இவை எல்லாம் எம்புட்டு பெரிசு.

நமது சூரிய குடும்பம் என்பது நாம் நிலா இல்லாத இரவில் பார்க்கும் ஒரு பனிபோன்ற/பால் போன்ற அடர்மேகத்தின் /பால்வழி மண்டலத்தில் ஒரு துளி
பால்வழிமண்டலம் ,நம் வீட்டில் பெரிய ஆப்பம் சுடுவோமே அதுபோல. . அந்த ஆப்பத்தின் ஓர் ஓரத்தில் ஒரு சீனித் துணுக்கை வைத்தது போன்றதுதான்,நம் சூரிய குடும்பம். அந்த சீனித்துகள் தான் நமது சூரிய குடும்பம். ஆப்பம் போன்றது பால்வழி மண்டலம். வானில பெரியதாகத் தெரிந்தாலும், அதனுடைய தாய்வீடான பால்வழி மண்டலத்தில் ஒரு சீனித்துகள் அளவே.

இந்த பால்வழிமண்டலத்தில் என்ன வெல்லாம் உள்ளன தெரியுமா? ஏராளமான செத்துப்போன ,செத்துக்கொண்டிருக்கும் விண்மீன்கள்,1000 கோடி வெள்ளைகுள்ளன்கள், 10 கோடி நியூட்ரான் விண்மீன்கள், மற்றும் நூற்றுக்கணக்கான கருந்துளைகள் இருக்கின்றன. இவைகளுக்கு விண்மீன்களில் இடையில் உள்ள பொருட்கள் உள்ளன.

கருந்துளைகள் இருப்பதை 1916 ல் கண்டுபிடித்தவர் Karl Schwarzschild. இது பற்றிய கருத்தினை ஆல்பர்ட் ஐன்ஸடீன் 1915ல், சார்பியல் விதியைச் சார்ந்து கூறினார். இதற்கு கருந்துளை என்று 1967ல் நாமகரணம் செய்தவர் ஜான் வீலர் என்ற விஞ்ஞானிதான். முதல் கருந்துளை முதன் முதல் 1971ல் தான் கண்டுபிடிக்கப்பப்ட்டது. இவைகளுக்கும் வயது உண்டு.Hawkins radiation என்றும் மிகக் மிகக் குறைந்த அளவு பொருளை வெளியில் விட்டுக்கொண்டு மெல்ல மெல்ல செத்துப்போகும். இது நடந்து முடிக்க இந்த பிரபஞசத்தின் வயதை விட அதிகம் ஆகலாம்.

இது இப்படி இருக்க, வானவியலாளர்கள் பலே கில்லாடிகள். 2018, ஜூன் 17 ,ம் நாள் ஒரு கருந்துளை/ நியூட்டரான் விண்மீன் பிறப்பைப் பற்றி தகவலை Northwestern University யின் சர்வதேச ஆய்வுமையம் பார்த்ததுடன் அதனைப் படமும் எடுத்துவிட்டார்கள் என்னே அறிவியலின் அதிசயம்.

ஹவாயின் W.M. Keck Observatory மற்றும் அரிஸோனாவின் MMT Observatory அறிவியலாளர்கள் இந்த தகவலை இப்போதுதான் 2019, ஜனவரி 10ம் நாள் வான் இயற்பியல் பத்திரிகையில் வெளியிட்டார்கள்.

ஜூன் மாதம் எடுத்த படத்தில் . திடீரென மாயமான வான் ஒளியை,கோடைகால வானில், வடக்குப்பக்கம் தொலை நோக்கியில் பார்க்கின்றனர்.பிறகு கொஞச நேரத்தில் அது மறைந்து போகிறது.அதனைச் சுற்றி ஏராளமான வெளிச்ச புள்ளிகள். அதனை கண்டுபிடித்து 80 நாட்கள் ஆராய்ந்த பின்னர் அது கருந்துளை /நியூட்ரான் விண்மீன் பிறப்பாக இருக்கலாம் என அறியப்படுகிறது. ,இதற்கு the Cow என்றும் பெயர் சூட்டியுள்ளனர்.இதனை தொலைநோக்கியில் பார்த்த அந்த சர்வதேச குழுவின் தலைவர் ரப்பெல்லா மார்குட்டி (Raffaella Margutti (பெண் ) இந்த cow கருந்துளையின் /நியூட்ரான் விண்மீன் பிறப்பாக இருக்கலாம்.நாங்க படித்த தெல்லாம், ஒரு விண்மீன் இருக்கும்போதுதான்,கருந்துளை.நியூட்ரான் பிறக்கிறது என. ஆனால் நேரில் பார்த்த அனுபவம் யாருக்கும் இல்லை என்கிறார். "We think that 'The Cow' is the formation of an accreting black hole or neutron star," said Northwestern's Raffaella Margutti, who led the research. "We know from theory that black holes and neutron stars form when a star dies, but we've never seen them right after they are born. Never.
இந்த கருந்துளை பிறப்பு பால்வழி மண்டலத்தில்ஹெர்குலிஸ் விண்மீன் தொகுதி/மண்டலத்தில் உள்ள CGCG 137-068 galaxyல் உள்ளது. இது பூமியிலிருந்து சுமார் 200 மில்லியன் ஒளியாண்டு(ஓர் ஒளியாண்டு = 9.6டிரில்லியன் கி. மீ) தூரத்தில் இருக்கிறது. இவ்வளவு தொலைவில் உள்ள வான்வெளியில்,நிகழ்ந்த கருந்துளை.நியூட்ரான் விண்மீன் பிறப்பை வானவியலாளர்கள் முதன் முறையாக ஹவாயில் உள்ள தொலைநோக்கி மூலம் பார்த்திருக்கிறார்கள் என்றால் ஆச்சரியமான தகவல் அல்லவா?

Glory in darkness

Marco Aurélio Ribeiro - Escritor

In this wide-angle image we see a dark cloud of cosmic dust, illuminated by the bright light of young stars. This dense cloud is actually a stellar formation region called Lupus 3, where extremely hot stars are born from masses of gas and dust that are collapsing. This image was created from data obtained with the light rail screening telescope and with the mpg / eso telescope of 2,2 meters, with the most detailed image of this region obtained today.

THE STELLAR FORMATION REGION LUPUS 3 is located in the constellation scorpion, only 600 Light-years away from earth. It is part of a larger complex called lupus clouds, which remove its name from the adjacent constellation of the wolf. The clouds reminiscent of smoke rippling against a background of millions of stars, however the object is effectively a dark nebula.

Nebulae are huge amounts of gas and dust between the stars, some extending over hundreds of light years. Although many nebulae are completely illuminated by the intense light emitted by hot stars, dark nebulae involve the light of celestial objects within them. They are also known as absorption nebulae, since they consist of dense, cold dust particles that absorb and disperse the light passing through the cloud.

Famous Dark Nebulae include the coal bag nebula and the great fissure, which are large enough to be seen with the naked eye, presenting particularly dark against the brightness of the milky way.

Lupus 3 presents an irregular form, like a misshapen snake that roams the sky. In this image it appears as a region of contrasts, with thick dark rails placed against the intense brightness of the bright blue stars located in the center. Like Most Dark Nebulae, Lupus 3 is an active star formation region composed mainly of protostars and very young stars. Nearby disturbances may cause denser lumps of the nebula to fall under its own gravity, becoming warm and with high pressure during the process. Eventually, the extreme conditions of these collapsing nuclei form protostars.

The two bright stars in the center of the image suffered this process. At the beginning of their lives, the light they emitted was virtually all blocked by the thick veil of their host nebula, being visible only with infrared or radio telescopes. However, as they grew more warm and bright, their intense light and strong stellar winds swept the gas and dust from the surrounding area, thus allowing their glorious emergence of dark motherhood, and shining now intensely.

Understanding Nebulae is crucial for understanding star formation processes - effectively, it is thought that the sun formed in a stellar formation region very similar to Lupus 3, more than 4 billion years ago. Being one of the nearest stellar maternity wards, Lupus 3 has been the subject of many studies; in 2013 the mpg / eso telescope of 2,2 meters, installed at the eso's La Silla Observatory in Chile, captured an image Minor of its dark columns similar to smoke and its bright stars (Eso1303).

The Fastest Ship In The Universe

A Star Within a Star (Thorne-Żytkow Object)

In 1977, Kip Thorne and Anna Żytkow figured out what happens when a neutron star - a ball of neutronium 25 kilometers across - hits a normal star. It's called a "Thorne-Żytkow object" or TŻO. Now astronomers may have found one in the Small Magellanic Cloud!

A Thorne-Żytkow Object Is a Star Within a Star

The neutron star slowly eats its host from within. Gas gets sucked into the neutron star and gets very hot: over a billion Celsius! The heat comes from two things: energy released when infalling gas hits the neutron star, and nuclear fusion after the gas hits.

How can you tell if a star is a Thorne-Żytkow object? If it's a red giant, the neutron star will make its core a lot hotter than usual. So, the "rapid proton process" should create elements that you don't usually see in such a star.

And now astronomers have found a red supergiant with a lot more rubidium, strontium, yttrium, zirconium, molybdenum and lithium than usual

"Discovery of a Thorne-Zytkow object candidate in the Small Magellanic Cloud": https://arxiv.org/abs/1406.0001

Expanding red giant stars will swallow too-close planets. In the solar system, the sun will engulf Mercury and Venus, and may devour Earth, as well.

Credit: James Gitlin/STScI AVL

Superb animation showing the indefinable expanse of our universe

How Most Antimatter Forms in Milky Way

A team of international astrophysicists led by ANU has shown how most of the antimatter in the Milky Way forms.

Antimatter is material composed of the antiparticle partners of ordinary matter -- when antimatter meets with matter, they quickly annihilate each other to form a burst of energy in the form of gamma-rays.

Scientists have known since the early 1970s that the inner parts of the Milky Way galaxy are a strong source of gamma-rays, indicating the existence of antimatter, but there had been no settled view on where the antimatter came from.

ANU researcher Dr Roland Crocker said the team had shown that the cause was a series of weak supernova explosions over millions of years, each created by the convergence of two white dwarfs which are ultra-compact remnants of stars no larger than two suns.

"Our research provides new insight into a part of the Milky Way where we find some of the oldest stars in our galaxy," said Dr Crocker from the ANU Research School of Astronomy and Astrophysics.

Dr Crocker said the team had ruled out the supermassive black hole at the centre of the Milky Way and the still-mysterious dark matter as being the sources of the antimatter.

He said the antimatter came from a system where two white dwarfs form a binary system and collide with each other. The smaller of the binary stars loses mass to the larger star and ends its life as a helium white dwarf, while the larger star ends as a carbon-oxygen white dwarf.

"The binary system is granted one final moment of extreme drama: as the white dwarfs orbit each other, the system loses energy to gravitational waves causing them to spiral closer and closer to each other," Dr Crocker said.

He said once they became too close the carbon-oxygen white dwarf ripped apart the companion star whose helium quickly formed a dense shell covering the bigger star, quickly leading to a thermonuclear supernova that was the source of the antimatter.

Story Source:

Materials provided by Australian National University.

Image : Artist's concept of the Milky Way Galaxy. GLAST will provide detailed information on where stars are forming.

Credit: NASA JPL

Cecile G. Tamura

18-Yr-Old Rifath Shaarook From Tamil Nadu Makes India Proud, Builds World’s Smallest & Lightest Satellite

Eight months of hard work, a team of seven youngsters from Tamil Nadu, a contest involving designs and models from 57 countries, and a winning model of a satellite that is only 64 grams in weight: seven Indian students have made the country proud by designing the world’s lightest and smallest satellite.

The Logical Indian spoke to the team’s leader, Rifath Shaarook. Rifath is only 18 years old and extremely passionate about space. He grew up in a science-crazy household, with his small room in Pallapatti, Karur, Tamil Nadu serving as his first research station.

“My dad, Mohamed Farook, was a scientist who did independent research in astronomy,” Rifath said. “He was an EC Engineer. He passed away in 2008 when I was 9. We always talked about space and astronomy in my childhood. I used to tell him that, one day, I would launch a satellite of my own. Now that’s dream is coming true but, sadly, my dad is no more with me.”

Shaarook built the 65gram (0.14lb) device as an exercise in demonstrating how well carbon fiber performs when 3D printed.

His invention is now set for a sub-orbital, four-hour mission in outer space.

During this short mission, the tiny satellite will be fully operational for 12 minutes in space’s micro-gravity.

“We designed it completely from scratch. It will have a new kind of on-board computer and eight indigenous built-in sensors to measure acceleration, rotation and the magnetosphere of the earth,” he told Business Standard.

Shaarook named the little tech-wonder after India’s science-loving former President Abdul Kalam. He calls it KalamSat.

Kalam spearheaded many initiatives and paved the way for the country’s aeronautical scientists to make great advancements in space exploration for India.

Shaarok’s background is a humble one. He comes from a small town in Tamil Nadu and is currently working as a lead scientist for Space Kidz India.

The program encourages and promotes young children and teenagers in India to study science and education.

Shaarok also has a history of invention. For example, three years prior, he built a variation of a helium weather balloon as part of a nationwide young scientist’s competition. 

Gravitational waves slow the spin of shape-shifting neutron star

Cecile G. Tamura

Put on the brakes. A spinning neutron star that shifts between two states slows at a faster rate in one of them – and gravitational waves may be responsible.

The neutron star J1023+0038 spins almost 600 times per second. But as its powerful magnetic field dissipates energy, it is slowing by about 76 rotations per second every billion years. This magnetic “spin-down” is normal, but sometimes J1023 slows at a faster rate.
The different rates are associated with two states the neutron star switches back and forth between: one where it emits mostly radio waves and one where it mainly gives off X-rays. No one knows why some neutron stars behave in this way. But when the star is emitting mostly X-rays, it slows down about 30 per cent faster.

In this X-ray phase, the star is stealing material from a smaller companion star that orbits it. Brynmor Haskell at the Polish Academy of Sciences in Warsaw and Alessandro Patruno at Leiden University, the Netherlands, argue that this stolen gas may be the key to J1023’s strange spin.

As material snatched from its companion sticks to J1023’s surface, it builds a so-called mountain. Despite being no more than a few millimetres in height, the bump crushes the atoms beneath it, pushing them deeper into the neutron star. There the higher pressure fuses them into heavier elements, giving the mountain roots in the star’s interior.

The extra surface bump and the heavier atoms below it together result in the mountain creating an asymmetry in J1023’s gravity. “Neutron stars are very compact, roughly the mass of the sun compressed in a 10-kilometre radius,” says Haskell. “This means that even very small deformations can lead to large changes in the gravitational field.”

Riding the waves

The imbalance in the neutron star’s gravitational field may cause it to radiate gravitational waves, ripples in space-time caused by the movement of massive objects. These waves would carry away some of the energy that keeps J1023 spinning.

When the star switches from its X-ray phase to its radio phase, it stops munching on its stellar partner. As a result, the mountain gradually flattens out and the star emits no more spin-stunting gravitational waves.

Last year, the LIGO collaboration announced that it had observed gravitational waves shaken off by black holes colliding. But nobody has yet seen gravitational waves from continuous, rather than catastrophic, events. Objects like J1023 are promising candidates for future gravitational wave searches, especially if they can grow larger mountains.

“If this happens, then there might be many other neutron stars that do the same,” says Patruno. “Continuous gravitational waves might really be a widespread phenomenon.”

Such a scenario could also explain the apparent cap on neutron stars’ spin. “The fastest ones we see don’t rotate as fast as we think they should be able to go,” says Nils Andersson at the University of Southampton, UK. “There’s something missing in our understanding.”

If faster-spinning stars have defects such as mountains, they would emit more gravitational waves and slow down faster, setting a cosmic speed limit for neutron stars.

https://arxiv.org/abs/1703.08374

https://www.newscientist.com/…/dn9730-neutron-star-clocked…/

http://onlinelibrary.wiley.com/jour…/10.1111/(ISSN)1365-2966

https://www.newscientist.com/…/dn9428-massive-neutron-star…/

https://www.newscientist.com/…/2077162-revolution-in-physi…/

Apollo 11 being rolled out to the launch site of the Kennedy Space Center in July, 1969.

Apollo 11 was the spaceflight that landed the first two humans on the Moon. Mission commander Neil Armstrong and pilot Buzz Aldrin, both American, landed the lunar module Eagle on July 20, 1969, at 20:18 UTC.

Inclination: 1.25°

Period: 2 hours

Launch date: July 16, 1969, 6:32 AM GMT-7

Dates: 16 Jul. 1969 – 24 Jul. 1969

Crew size: 3

Operator: NASA

Members: Neil Armstrong, Michael Collins, Buzz Aldrin

Astronomers have found at least seven Earth-sized planets orbiting the same star 40 light-years away.

The NASA Announcement

This discovery outside of our solar system is rare because the planets have the winning combination of being similar in size to Earth and being all temperate, meaning they could have water on their surfaces and potentially support life.

This is the first time that so many planets of this kind are found around the same star.
The seven exoplanets were all found in tight formation around an ultracool dwarf star called TRAPPIST-1. Estimates of their mass also indicate that they are rocky planets, rather than being gaseous like Jupiter. Three planets are in the habitable zone of the star, known as TRAPPIST-1e, f and g, and may even have oceans on the surface.
The TRAPPIST-1 star, an ultracool dwarf, has seven Earth-size planets orbiting it.
The researchers believe that TRAPPIST-1f, in particular, is the best candidate for supporting life. It's a bit cooler than Earth but could be suitable for the right atmosphere and enough greenhouse gasses
.
What's next
Over the next decade, the researchers want to define the atmosphere of each planet, as well as to determine whether they truly do have liquid water on the surface and search for signs of life.
Although 40 light-years away doesn't sound too far, it would take us millions of years to reach this star system. But from a research perspective, it's a close opportunity and the best target to search for life beyond our solar system.

ஸ்பிட்செர் மூலம் புதிய கோள்களை நாசா கண்டுபிடித்தது. புதிதாக கண்டுபிடிக்கப்பட்ட 
7 கோள்களில் 3 கோள்கள் மனிதர்கள் வசிப்பதற்கு ஏற்ற இடம் உள்ளதாக நாசா 
தெரிவித்துள்ளது.

பூமியை போலவே உயிர்கள் வாழக்கூடிய வேறு கிரகங்கள் உள்ளனவா என்ற 
ஆராய்ச்சியில் பல நாடுகளும் தொடர்ந்து ஈடுபட்டு வருகின்றன. வேற்றுகிரகத்தில் 
மனிதர்கள் வசிக்கிறார்களா என்பதை அறியும் ஆராய்ச்சியும் நடக்கிறது. இந்நிலையில், 
பூமியில் இருந்து 39 ஒளி ஆண்டுகள் தூரத்தில் 7 கோள்கள் இருப்பதை நாசா 
கண்டுபிடித்துள்ளது. ஸ்பிட்செர் மூலம் புதிய கோள்களை நாசா கண்டுபிடித்தது. 
புதிதாக கண்டுபிடிக்கப்பட்ட 7 கோள்களில் 3 கோள்கள் மனிதர்கள் வசிப்பதற்கு 
ஏற்ற இடம் உள்ளதாக நாசா தெரிவித்துள்ளது.

அங்கு மனிதர்கள் உயிர்வாழ்வதற்கான காற்று, நீர் இருப்பதற்கான வாய்ப்புகள் 
அதிகம் என நாசா விஞ்ஞானிகள் கருதுகின்றனர். மேலும், பூமியை போன்றே 
மேற்பரப்பும் அடர்த்தியும் காணப் படுகிறது. மிகுந்த வெளிச்சத்துடன் உள்ள 
இந்த கிரகங்களை இரவில் வெறும் கண்களாலேயே காண முடியும் என்று 
நாசா விஞ்ஞானிகள் கூறியுள்ளதாக தகவல்கள் தெரிவிக்கின்றன. 3 கோள்களில்
 நீர் ஆதாரம் இருப்பதையும் நாசா விஞ்ஞானிகள் கண்டுபிடித்துள்ளனர்.

Dark energy emerges when energy conservation is violated

Cecile G. Tamura

The conservation of energy is one of physicists' most cherished principles, but its violation could resolve a major scientific mystery: why is the expansion of the universe accelerating? That is the eye-catching claim of a group of theorists in France and Mexico, who have worked out that dark energy can take the form of Albert Einstein's cosmological constant by effectively sucking energy out of the cosmos as it expands.

The cosmological constant is a mathematical term describing an anti-gravitational force that Einstein had inserted into his equations of general relativity in order to counteract the mutual attraction of matter within a static universe. It was then described by Einstein as his "biggest blunder", after it was discovered that the universe is in fact expanding. But then the constant returned to favour in the late 1990s following the discovery that the universe's expansion is accelerating.

For many physicists, the cosmological constant is a natural candidate to explain dark energy. Since it is a property of space–time itself, the constant could represent the energy generated by the virtual particles that quantum mechanics dictates continually flit into and out of existence. Unfortunately the theoretical value of this "vacuum energy" is up to a staggering 120 orders of magnitude larger than observations of the universe's expansion imply.

Running total

The latest work, carried out by Alejandro Perez and Thibaut Josset of Aix Marseille University together with Daniel Sudarsky of the National Autonomous University of Mexico, proposes that the cosmological constant is instead the running total of all the non-conserved energy in the history of the universe. The "constant" in fact would vary – increasing when energy flows out of the universe and decreasing when it returns. However, the constant would appear unchanging in our current (low-density) epoch because its rate of change would be proportional to the universe's mass density. In this scheme, vacuum energy does not contribute to the cosmological constant.

The researchers had to look beyond general relativity because, like Newtonian mechanics, it requires energy to be conserved. Strictly speaking, relativity requires the conservation of a multi-component "energy-momentum tensor". That conservation is manifest in the fact that, on very small scales, space–time is flat, even though Einstein's theory tells us that mass distorts the geometry of space–time.

In contrast, most attempts to devise a theory of quantum gravity require space–time to come in discrete grains at the smallest (Planck-length) scales. That graininess opens the door to energy non-conservation. Unfortunately, no fully formed quantum-gravity theory exists yet, and so the trio instead turned to a variant of general relativity known as unimodular gravity, which allows some violation of energy conservation. They found that when they constrained the amount of energy that can be lost from (or gained by) the universe to be consistent with the cosmological principle – on very large scales the process must be both homogeneous and isotropic – the unimodular equations generated a cosmological-constant-like entity.

Modified quantum mechanics

In the absence of a proper understanding of Planck-scale space–time graininess, the researchers were unable to calculate the exact size of the cosmological constant. Instead, they incorporated the unimodular equations into a couple of phenomenological models that exhibit energy non-conservation. One of these describes how matter might propagate in granular space–time, while the other modifies quantum mechanics to account for the disappearance of superposition states at macroscopic scales.

These models both contain two free parameters, which were adjusted to make the models consistent with null results from experiments that have looked for energy non-conservation in our local universe. Despite this severe constraint, the researchers found that the models generated a cosmological constant of the same order of magnitude as that observed. "We are saying that even though each individual violation of energy conservation is tiny, the accumulated effect of these violations over the very long history of the universe can lead to dark energy and accelerated expansion," Perez says.

In future, he says it might be possible to subject the new idea to more direct tests, such as observing supernovae very precisely to try to work out whether the universe's accelerating expansion is driven by a constant or varying force. The model could also be improved so that it captures dark-energy's evolution from just after the Big Bang – and then comparing the results with observations of the cosmic microwave background.

If the trio are ultimately proved right, it would not mean physicists having to throw their long-established conservation principles completely out of the window. A variation in the cosmological constant, Perez says, could point to a deeper, more abstract kind of conservation law. "Just as heat is energy stored in the chaotic motion of molecules, the cosmological constant would be 'energy' stored in the dynamics of atoms of space–time," he explains. "This energy would only appear to be lost if space–time is assumed to be smooth."

Fanciful yet viable

Other physicists are cautiously supportive of the new work. George Ellis of the University of Cape Town in South Africa describes the research as "no more fanciful than many other ideas being explored in theoretical physics at present". The fact that the models predict energy to be "effectively conserved on solar-system scales" – a crucial check, he says – makes the proposal "viable" in his view.
Lee Smolin of the Perimeter Institute for Theoretical Physics in Canada, meanwhile, praises the researchers for their "fresh new idea", which he describes as "speculative, but in the best way". He says that the proposal is "probably wrong", but that if it's right "it is revolutionary".

http://www.phy.olemiss.edu/~luca/Topics/u/unimodular.html

http://journals.aps.org/…/ab…/10.1103/PhysRevLett.118.021102
http://physicsworld.com/…/dark-energy-emerges-when-energy-c…

https://en.wikipedia.org/wiki/Dark_energy

https://en.wikipedia.org/wiki/Cosmological_constant

http://www.sciencemag.org/…/simple-explanation-mysterious-s…

https://arxiv.org/pdf/1604.04183v3.pdf

https://www.nasa.gov/chand…/news/mysterious-xray-signal.html

NASA's Kepler Mission Rewrites Drake's Equation --"Humans Not the First Technological Civilization in the Universe"

Cecile G. Tamura

"The question of whether advanced civilizations exist elsewhere in the universe has always been vexed with three large uncertainties in the Drake equation," said Adam Frank, professor of physics and astronomy at the University of Rochester. "We've known for a long time approximately how many stars exist. We didn't know how many of those stars had planets that could potentially harbor life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct."

As Frank puts it "We don't even know if it's possible to have a high-tech civilization that lasts more than a few centuries." With Frank and Sullivan's new result, scientists can begin using everything they know about planets and climate to begin modeling the interactions of an energy-intensive species with their home world knowing that a large sample of such cases has already existed in the cosmos.

"Our results imply that our biological, and cultural evolution has not been unique and has probably happened many times before. The other cases are likely to include many energy intensive civilizations dealing with crises on their planets as their civilizations grow. That means we can begin exploring the problem using simulations to get a sense of what leads to long lived civilizations and what doesn't."

A new study shows that the recent discoveries of exoplanets combined with a broader approach to the question makes it possible to assign a new empirically valid probability to whether any other advanced technological civilizations have ever existed. And it shows that unless the odds of advanced life evolving on a habitable planet are astonishingly low, then human kind is not the universe's first technological, or advanced, civilization.

The paper, published in Astrobiology, also shows for the first time just what "pessimism" or "optimism" mean when it comes to estimating the likelihood of advanced extraterrestrial life.

"Thanks to NASA's Kepler satellite and other searches, we now know that roughly one-fifth of stars have planets in 'habitable zones,' where temperatures could support life as we know it. So one of the three big uncertainties has now been constrained."

Frank said that Drake's third big question--how long civilizations might survive--is still completely unknown. "The fact that humans have had rudimentary technology for roughly ten thousand years doesn't really tell us if other societies would last that long or perhaps much longer," he explained.

The illustration of the Drake equation and the Frank equation is shown below. In 1961, astrophysicist Frank Drake developed an equation to estimate the number of advanced civilizations likely to exist in the Milky Way galaxy.

The Drake equation (top row) has proven to be a durable framework for research, and space technology has advanced scientists' knowledge of several variables. But it is impossible to do anything more than guess at variables such as L, the probably longevity of other advanced civilizations.

In their new research, Frank and Woodruff Sullivan offer a new equation (bottom row) to address a slightly different question: What is the number of advanced civilizations likely to have developed over the history of the observable universe? Frank and Sullivan's equation draws on Drake's, but eliminates the need for L.

"Rather than asking how many civilizations may exist now, we ask 'Are we the only technological species that has ever arisen?': said Sullivan. "This shifted focus eliminates the uncertainty of the civilization lifetime question and allows us to address what we call the 'cosmic archaeological question' -- how often in the history of the universe has life evolved to an advanced state?"

That still leaves huge uncertainties in calculating the probability for advanced life to evolve on habitable planets. It's here that Frank and Sullivan flip the question around. Rather than guessing at the odds of advanced life developing, they calculate the odds against it occurring in order for humanity to be the only advanced civilization in the entire history of the observable universe.

With that, Frank and Sullivan then calculated the line between a Universe where humanity has been the sole experiment in civilization and one where others have come before us.

"Of course, we have no idea how likely it is that an intelligent technological species will evolve on a given habitable planet," says Frank. But using our method we can tell exactly how low that probability would have to be for us to be the ONLY civilization the Universe has produced. We call that the pessimism line. If the actual probability is greater than the pessimism line, then a technological species and civilization has likely happened before."

Using this approach, Frank and Sullivan calculate how unlikely advanced life must be if there has never been another example among the universe's twenty billion trillion stars, or even among our own Milky Way galaxy's hundred billion.

The result? By applying the new exoplanet data to the Universe as a whole, Frank and Sullivan find that human civilization is likely to be unique in the cosmos only if the odds of a civilization developing on a habitable planet are less than about one in 10 billion trillion, or one part in 10 to the 22th power.

"One in 10 billion trillion is incredibly small," says Frank "To me, this implies that other intelligent, technology producing species very likely have evolved before us. Think of it this way. Before our result you'd be considered a pessimist if you imagined the probability of evolving a civilization on a habitable planet were, say, one in a trillion. But even that guess, one chance in a trillion, implies that what has happened here on Earth with humanity has in fact happened about a 10 billion other times over cosmic history!"

For smaller volumes the numbers are less extreme. For example, another technological species likely has evolved on a habitable planet in our own Milky Way galaxy if the odds against it evolving on any one habitable planet are better than one chance in 60 billion.
But if those numbers seem to give ammunition to the "optimists" about the existence of alien civilizations, Sullivan points out that the full Drake equation -- which calculates the odds that other civilizations are around today -- may give solace to the pessimists.

"The universe is more than 13 billion years old," said Sullivan. "That means that even if there have been a thousand civilizations in our own galaxy, if they live only as long as we have been around -- roughly ten thousand years -- then all of them are likely already extinct. And others won't evolve until we are long gone. For us to have much chance of success in finding another "contemporary" active technological civilization, on average they must last much longer than our present lifetime."

"Given the vast distances between stars and the fixed speed of light we might never really be able to have a conversation with another civilization anyway," said Frank. "If they were 50,000 light years away then every exchange would take 100,000 years to go back and forth."

But, as Frank and Sullivan point out, even if there aren't other civilizations in our galaxy to communicate with now, the new result still has a profound scientific and philosophical importance. "From a fundamental perspective the question is 'has it ever happened anywhere before?'" said Frank. "And it is astonishingly likely that we are not the only time and place that an advance civilization has evolved."

According to Frank and Sullivan their result has a practical application as well. As humanity faces its crisis in sustainability and climate change we can wonder if other civilization-building species on other planets have gone through a similar bottleneck and made it to the other side.

https://www.rochester.edu/news/are-we-alone-in-the-universe/

http://www.seti.org/node/993

http://www.dailygalaxy.com/…/nasas-kepler-mission-discoveri