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Na rubu znanosti Istraživanja bez granica

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Old 16.12.2016., 19:10   #101
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Ovo bi moglo označiti revoluciju u našem razumjevanju svemira i sila koje tamo djeluju.

Quote:
https://www.newscientist.com/article...f-dark-matter/

First test of rival to Einstein’s gravity kills off dark matter

A controversial approach to gravity that challenges Albert Einstein and suggests dark matter doesn’t exist has passed its first test.

The vast majority of physicists agree that gravity acts according to rules laid down in Isaac Newton’s law of gravitation and Einstein’s theory of general relativity. Yet observations of the universe show that the motion of the galaxies can’t be explained by the gravitational pull of all the ordinary matter out there – hence the belief in unseen, dark matter that exerts its own pull.

Now, a team of astronomers studying the distribution of matter in more than 30,000 galaxies say their observations can be explained by an alternative theory that does away with dark matter. If this “modified gravity” is correct, it would up-end hundreds of years of fundamental physics.

.....


orginal dokument:
DOI :10.1093/mnras/stw3192

preprint:
Quote:
https://arxiv.org/pdf/1612.03034v1.pdf

First test of Verlinde’s theory of Emergent Gravity using
Weak Gravitational Lensing measurements


Verlinde (2016) proposed that the observed excess gravity in galaxies and clusters is the consequence of Emergent Gravity (EG). In this theory the standard gravitational laws are modified on galactic and larger scales due to the displacement of dark energy by baryonic matter. EG gives an estimate of the excess gravity (described as an apparent dark matter density) in terms of the baryonic mass distribution and the Hubble parameter. In this work we present the first test of EG using weak gravitational lensing, within the regime of validity of the current model. Although there is no direct description of lensing and cosmology in EG yet, we can make a reasonable estimate of the expected lensing signal of low redshift galaxies by assuming a background LambdaCDM cosmology. We measure the (apparent) average surface mass density profiles of 33,613 isolated central galaxies, and compare them to those predicted by EG based on the galaxies' baryonic masses. To this end we employ the ~180 square degrees overlap of the Kilo-Degree Survey (KiDS) with the spectroscopic Galaxy And Mass Assembly (GAMA) survey. We find that the prediction from EG, despite requiring no free parameters, is in good agreement with the observed galaxy-galaxy lensing profiles in four different stellar mass bins. Although this performance is remarkable, this study is only a first step. Further advancements on both the theoretical framework and observational tests of EG are needed before it can be considered a fully developed and solidly tested theory.


video:
Erik Verlinde: A new explanation of gravity
Erik Verlinde - The Hidden Phase Space of Our Universe
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Old 17.12.2016., 01:57   #102
sorry ali ne.
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Old 17.12.2016., 15:53   #103
?
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Old 19.12.2016., 10:44   #104
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Potvrda o H2O na Ceresu.

Vode zapravo ima svugdje po našem zvjezdanom sustavu i to nije nikakva prepreka za kolonizaciju (kao što se do 'nekidan' tvrdilo i još uvijek se uči u školama).

Jedina je prepreka smo mi, tj. što još nemamo tehnologiju kojom bi se konačno odlijepili od matičnog planeta.


Quote:
http://www.space.com/35035-water-on-...nt-shadow.html

Just like the moon and Mercury, the largest asteroid in Earth's solar system, Ceres, has cold pockets of perpetual darkness on its surface where researchers have now detected ice, a new study finds.

It remains a mystery, however, why only small amounts of ice were detected in these shadowy crater floors, the authors of the new research say.

With a diameter of about 585 miles (940 kilometers), Ceres is referred to as both an asteroid and a dwarf planet. It is the dwarf planet closest to Earth and the largest member of the solar system's main asteroid belt, located between Mars and Jupiter.
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Old 19.12.2016., 20:25   #105
Bože da je ovoga tamo poslati. Pa bi shvatio kako voda nije jedino što treba za biti na nekoj planeti.
Gdje je struja, gdje je hrana, gdje je habitat, zaštita od meteorita (površina je sva izrešetana i puna kratera) i najvažnije gdje je karta za povratak kući. Jer jedno je doći tamo a vratiti se živ je nešto sasvim drugo. ALi tko ne zna, misli kako je sve "tek tako".
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Old 01.01.2017., 21:25   #106
KIC 8462852 ilitiga Tabby Star i dalje privlači zagovornike Majke Prirode, koji opet se sramote novo tezom. Meni je više neugodno gledat, kako se sramote







Evo najnovijeg 'izuma' Majke Prirode ...... Magnetic-Field Avalanches

orginal dokument:
Quote:
DOI: 10.1103/PhysRevLett.117.261101


ABSTRACT
The star KIC8462852 (Tabby’s star) has shown anomalous drops in light flux. We perform a statistical analysis of the more numerous smaller dimming events by using methods found useful for avalanches in ferromagnetism and plastic flow. Scaling exponents for avalanche statistics and temporal profiles of the flux during the dimming events are close to mean field predictions. Scaling collapses suggest that this star may be near a nonequilibrium critical point. The large events are interpreted as avalanches marked by modified dynamics, limited by the system size, and not within the scaling regime.
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Old 22.02.2017., 19:50   #107
Lightbulb NASA prijelomna vijest

Izgleda kako su konačno našli nešto zanimljivo.

Iako sam malo skeptičan, kad vidim brzine orbita i tip zvijezde.


VIDEO:
https://www.youtube.com/watch?v=tiDpZ7cE-pQ
https://www.youtube.com/watch?v=P_II70YXFD8




Quote:
http://www.index.hr/vijesti/clanak/l...ta/952271.aspx
Prema radu predstavljenom u prestižnom časopisu Nature, sustav je udaljen oko 40 svjetlosnih godina, a planeti kruže oko hladne patuljaste zvijezde TRAPPIST-1. Tri od planeta nalaze se u zoni Zlatokose što znači da bi na njima mogli postojati oceani, a na temelju procesa u kojima su nastali može se zaključiti da vjerojatno imaju i atmosferu. Uz to gravitacijske sile koje djeluju na planete 'masiraju' njihove unutrašnjosti tako da usporavaju njihovo hlađenje. To, među ostalim, znači da bi trebali biti i tektonski i geološki aktivni poput Jupiterova mjeseca Io. Najmanje šest unutrašnjih ima gustoću koja odgovara kamenim planetima. Svi navedeni čimbenici zajedno dobar su razlog za pretpostavku da bi u sustavu mogli postojati uvjeti za život. U svakom slučaju to je planetarni sustav s najvećim brojem objekata koji bi mogli imati tekuću vodu i život koji je ikada do sada pronađen. Stoga će biti vrlo važan cilj budućih astronomskih i astrobioloških istraživanja.


Quote:
https://arstechnica.com/science/2017...abitable-zone/

Less than a year ago, an international team of astronomers put the star TRAPPIST-1 in the news. TRAPPIST-1 itself is unremarkable, belonging to the class of small, dim stars known as "ultracool dwarfs." Rather, it was the presence of three planets orbiting the star that made the news. While they probably orbit too close to support liquid water, TRAPPIST-1's proximity to Earth—it's less than 40 light years away—makes detailed observations of any planetary atmospheres a realistic possibility.

But the orbit of the outermost planet, TRAPPIST-1d, wasn't well defined by the initial observations, causing its discoverers to go back for some followup observations. Those turned up four more planets, three of which are likely to be in the habitable zone of their host star. As the orbit of the outer one is, once again, uncertain, more observations will undoubtedly be in the works. Who knows what they'll turn up?


orginal dokument:
Quote:
http://www.nature.com/nature/journal...ture21360.html

One aim of modern astronomy is to detect temperate, Earth-like exoplanets that are well suited for atmospheric characterization. Recently, three Earth-sized planets were detected that transit (that is, pass in front of) a star with a mass just eight per cent that of the Sun, located 12 parsecs away1. The transiting configuration of these planets, combined with the Jupiter-like size of their host star—named TRAPPIST-1—makes possible in-depth studies of their atmospheric properties with present-day and future astronomical facilities1, 2, 3. Here we report the results of a photometric monitoring campaign of that star from the ground and space. Our observations reveal that at least seven planets with sizes and masses similar to those of Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain, such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inwards4, 5. Moreover, the seven planets have equilibrium temperatures low enough to make possible the presence of liquid water on their surfaces.
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Old 10.03.2017., 22:02   #108
Lightbulb

Većina misli kako u vakumu svemira ne postoji sila otpora, ali tu se izgleda nešto čudno pomalja na horizontu.



Quote:
http://www.sciencealert.com/physicis...perfect-vacuum
One of the most fundamental tenets of modern physics is that in a perfect vacuum - a place entirely devoid of matter - no friction can possibly exist, because empty space cannot exert a force on objects travelling through it.
orginal dokument:
Quote:
DOI: 10.1103/PhysRevLett.118.053601

ABSTRACT
We show how a simple calculation leads to the surprising result that an excited two-level atom moving through a vacuum sees a tiny friction force of first order in v/c. At first sight this seems to be in obvious contradiction to other calculations showing that the interaction with the vacuum does not change the velocity of an atom. It is even more surprising that this change in the atom’s momentum turns out to be a necessary result of energy and momentum conservation in special relativity.
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Old 05.06.2017., 23:22   #109
Lightbulb

Nedavno je opet nešto MASIVNO zaklonilo zvijezdu Tabby AKA KIC 8462852.



Quote:
http://www.space.com/36925-alien-meg...ing-again.html
The perplexing cosmic object known as "Boyajian's star" is once again exhibiting a mysterious pattern of dimming and brightening that scientists have tried to explain with hypotheses ranging from swarms of comets to alien megastructures.

Today (May 19), an urgent call went out to scientists around the world to turn as many telescopes as possible toward the star, to try and crack the mystery of its behavior.

"At about 4 a.m. this morning I got a phone call … that Fairborn [Observatory] in Arizona had confirmed that the star was 3 percent dimmer than it normally is," Jason Wright, an associate professor of astronomy at Pennsylvania State University, who is managing a study of Boyajian's star, said during a live webcast today at 2 p.m. EDT (1800 GMT). "That is enough that we are absolutely confident that this is no statistical fluke. We've now got it confirmed at multiple observatories, I think."
Usput evo još jedne nebulozne hipoteze oko te misteriozne zvijezde Tabby

https://arxiv.org/pdf/1705.08427.pdf

Quote:
ABSTRACT
KIC 8462852 stood out among more than 100,000 stars in the Kepler catalogue because
of the strange features of its light curve: a wide and asymmetric dimming taking
up to 15 per cent of the total light, together with a period of multiple, narrow dimmings
happening approximately 700 days later. Several models have been proposed to
account for this abnormal behaviour, most of which require either unlikely causes or
a finely-tuned timing. We aim at offering a relatively natural solution, invoking only
phenomena that have been previously observed, although perhaps in larger or more
massive versions. We model the system using a large, ringed body whose transit produces
the first dimming and a swarm of Trojan objects sharing its orbit that causes
the second period of multiple dimmings. The resulting orbital period is T ≈ 12 years,
with a semi-major axis a ≈ 6 au. Our model allows us to make two straightforward
predictions: we expect the passage of a new swarm of Trojans in front of the star
starting during the early months of 2021, and a new transit of the main object during
the first half of 2023.



Ali već i djeca iz vrtića znaju, kako i znanstveni radovi znaju biti nepresušni izvori gluposti i viceva.

Evo zašto je ova teza samo za smijanje i razonodu:

Quote:
https://www.newscientist.com/article...tructure-star/
Problem of scale
But the model isn’t perfect. “There are lots of problems, but at least they are only ‘scale’ problems,” says co-author Alberto Fernández-Soto at the University of Cantabria in Spain. In other words, we have seen these things before, just on much smaller scales, he says.

The planet, for example, would be so large that it could be a small star. And the swarm of asteroids would need to contain as much mass as Jupiter, though it’s not clear whether that is physically possible.

David Kipping at Columbia University in New York and Jason Wright at Pennsylvania State University agree that a strength of the model is that it only uses conventional astrophysics – but scaling is an issue.
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Old 15.06.2017., 18:00   #110
Lightbulb




Quote:
https://www.space.com/37155-astronom...id-mining.html

Smithsonian astrophysicist Martin Elvis would like to see astronomers take on a crucial role for future asteroid mining: as astronomical prospectors scoping out the next big catch.

Elvis, a researcher with the Harvard-Smithsonian Center for Astrophysics in Massachusetts, discussed his dream for applied astronomy June 4 here at the Dawn of Private Space Science Symposium. Efficient asteroid mining would jump-start a space economy and bring down costs for exploration and space science, guiding humans into a modern space age, he said.
Možda konačno krenemo u pravom smjeru i odhebemo više 'simbolične' projekte, koji samo donose enormne gubitke uz minimalnu korist.
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Old 15.06.2017., 18:22   #111
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Evo i hrvatske teorije o Svemiru





Quote:
https://journals.aps.org/prd/abstrac...RevD.95.103519

ABSTRACT
In this work we propose a new general model of the eternal cyclic Universe. We start from the assumption that quantum gravity corrections can be effectively accounted by the addition of higher order curvature terms in the Lagrangian density for gravity. It is also taken into account that coefficients associated with these curvature corrections will in general be dependent on a curvature regime. We therefore assume no new ingredients, such as extra dimensions, new scalar fields, phantom energy or special space-time geometries. Evolution of the Universe in this framework is studied and general properties of each phase of the cycle—cosmological bounce, low curvature (ΛCDM) phase, destruction of bounded systems and contracting phase—are analyzed in detail. Focusing on some simple special cases, we obtain analytical and numerical solutions for each phase confirming our analysis.
orginal dokument:
https://arxiv.org/pdf/1701.03657v3.pdf


Evo članak i na hrvatskom:
Quote:
http://www.jutarnji.hr/life/znanost/...svega/6244206/

Dvojica mladih hrvatskih fizičara Petar Pavlović i Marko Sossich objavila su članak u prestižnom znanstvenom časopisu Physical Review D u kojemu propituju mogućnost novog kozmološkog modela svemira koji bi bio alternativa uvriježenom modelu Velikog praska.
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Old 08.10.2017., 19:57   #112
UMRLA JEDNA OD NAJOMILJENIJIH RADIJSKIH NOVINARKI I VODITELJICA

Preminula je Tanja Devčić, dugogodišnja urednica kultne emisije Andromeda





radio emisija ANDROMEDA


Ona i Ante (kasnije i Korado) su više učinili za popularizaciju astronomije (i znanosti), nego sve žalosne sove iz HAZU-a.

Počivala u miru.
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