Monday, 24 February 2014

Could Jupiter become a star? Feb 21, 2014 by Fraser Cain, Universe Today

NASA's Galileo spacecraft arrived at Jupiter on December 7, 1995, and proceeded to study the giant planet for almost 8 years. It sent back a tremendous amount of scientific information that revolutionized our understanding of the Jovian system. By the end of its mission, Galileo was worn down. Instruments were failing and scientists were worried they wouldn't be able to communicate with the spacecraft in the future. If they lost contact, Galileo would continue to orbit the Jupiter and potentially crash into one of its icy moons.
Galileo would certainly have Earth bacteria on board, which might contaminate the pristine environments of the Jovian moons, and so NASA decided it would be best to crash Galileo into Jupiter, removing the risk entirely. Although everyone in the scientific community were certain this was the safe and wise thing to do, there were a small group of people concerned that crashing Galileo into Jupiter, with its Plutonium thermal reactor, might cause a cascade reaction that would ignite Jupiter into a second star in the Solar System.
Hydrogen bombs are ignited by detonating plutonium, and Jupiter's got a lot of hydrogen. Since we don't have a second star, you'll be glad to know this didn't happen. Could it have happened? Could it ever happen? The answer, of course, is a series of nos. No, it couldn't have happened. There's no way it could ever happen… or is there?
Jupiter is mostly made of hydrogen, in order to turn it into a giant fireball you'd need oxygen to burn it. Water tells us what the recipe is. There are two atoms of hydrogen to one atom of oxygen. If you can get the two elements together in those quantities, you get water.
In other words, if you could surround Jupiter with half again more Jupiter's worth of oxygen, you'd get a Jupiter plus a half sized fireball. It would turn into water and release energy. But that much oxygen isn't handy, and even though it's a giant ball of fire, that's still not a star anyway. In fact, stars aren't "burning" at all, at least, not in the combustion sense.
Our Sun produces its energy through fusion. The vast gravity compresses hydrogen down to the point that high pressure and temperatures cram hydrogen atoms into helium. This is a fusion reaction. It generates excess energy, and so the Sun is bright. And the only way you can get a reaction like this is when you bring together a massive amount of hydrogen. In fact… you'd need a star's worth of hydrogen. Jupiter is a thousand times less massive than the Sun. One thousand times less massive. In other words, if you crashed 1000 Jupiters together, then we'd have a second actual Sun in our Solar System.
But the Sun isn't the smallest possible star you can have. In fact, if you have about 7.5% the mass of the Sun's worth of hydrogen collected together, you'll get a red dwarf star. So the smallest red dwarf star is still about 80 times the mass of Jupiter. You know the drill, find 79 more Jupiters, crash them into Jupiter, and we'd have a second star in the Solar System.
There's another object that's less massive than a red dwarf, but it's still sort of star like: a brown dwarf. This is an object which isn't massive enough to ignite in true fusion, but it's still massive enough that deuterium, a variant of hydrogen, will fuse. You can get a brown dwarf with only 13 times the mass of Jupiter. Now that's not so hard, right? Find 13 more Jupiters, crash them into the planet?
As was demonstrated with Galileo, igniting Jupiter or its hydrogen is not a simple matter.
We won't get a second star unless there's a series of catastrophic collisions in the Solar System.

And if that happens… we'll have other problems on our hands.

Saturday, 15 February 2014

"The Fabric of Space and Time is in Turmoil" --More on Stephen Hawking's Black Hole Update, - 14th, Feb.'2014

On January 24, the journal Nature published an article entitled "There are no black holes." In a brief article published on arXiv, a scientific preprint server, Stephen Hawking, currently Director of Research at the Centre for Theoretical Cosmology at the University of Cambridge, proposed a theory of black holes that could reconcile the principles of general relativity and quantum physics.
"According to Einstein's theory of general relativity, a black hole is kind of cosmic central vacuum cleaner that swallows everything in its reach and lets nothing escape. It emits no radiation," says Robert Lamontagne, an astrophysicist at the Department of Physics, Université de Montréal, and Executive Director of the Observatoire du Mont-Mégantic.Since it is not visible and has no boundaries as such, a black hole is classically defined by an area of space called the "event horizon," where nothing can escape. "Beyond this horizon, matter and light flow freely, but as soon as the horizon's intangible boundary is crossed, matter and light become trapped," he says.
However, if we use quantum mechanics to describe a black hole, the laws of thermodynamics must apply. In this description, a black hole emits particles in the form of radiation and, ultimately, evaporates. Hawking himself predicted this in the 1970s.
"Following through with Hawking's argument, we conclude that if there is evaporation there must be a boundary to the event horizon, a place of transition between the inside and outside of the black hole," says Lamontagne. "A high energy envelope, a firewall, which burns up matter, is proposed."
However, this scenario poses a problem: if the firewall exists, we should be able to see it. Furthermore, the existence of a firewall around a black hole is inconsistent with the theory of general relativity.
While the two major theories, that of general relativity (a theory of gravity) and quantum mechanics (a description of the microscopic world), work well in their respective fields, they are not universal: neither can explain alone how black holes work.
"The Holy Grail would be to find THE theory that would unify the other two. And Stephen Hawking has come back with a new proposal," says Lamontagne. Roughly, Hawking suggests that if the firewall is not visible, it is because its position fluctuates constantly and rapidly. "Hawking says, and this is purely hypothetical, that the fabric of space and time is in turmoil and we cannot define its whereabouts."
In short, since we cannot change the principles of either quantum mechanics or general relativity, Hawking proposes to slightly modify the description of black holes. Hence his remark that black holes do not exist the way we thought they did, as we thought we knew them.
In our galaxy, black holes are less numerous than suggested by sci-fi movies. The largest black hole near us is at the center of our galaxy - the Milky Way. It is 30,000 light-years from Earth. Its mass is about one million times that of the Sun, and it occupies a space equivalent to our solar system.
"We cannot see it directly but we have located it because of effects we can observe using various technological methods: it constantly deviates the trajectories of stars in its vicinity," says Lamontagne. Moreover, in 2014, a huge cloud of gas will fall toward this "nearby" black hole. "This is exciting from an astronomical point of view because we will be able to examine the phenomenon for 10 to 20 years to come."
The image at the top of the page shows a rapid X-ray flare that was observed from the direction of the supermassive black hole that resides at the center of our galaxy. This violent flare captured by NASA's Chandra X-ray Observatory has given astronomers an unprecedented view of the energetic processes surrounding this supermassive black hole.
A team of scientists led by Frederick K. Baganoff of MIT detected a sudden X-ray flare while observing Sagiattarius A*, a source of radio emission believed to be associated with the black hole at the center of
our Galaxy.
"This is extremely exciting because it's the first time we have seen our own neighborhood supermassive black hole devour a chunk of material," said Baganoff. "This signal comes from closer to the event horizon of our Galaxy's supermassive black hole than any that we have ever received before. It's as if the material there sent us a postcard before it fell in."
In a just few minutes, Sagittarius A** became 45 times brighter in X-rays, before declining to pre-flare levels a few hours later. At the peak of the flare, the X-ray intensity dramatically dropped by a factor of five within just a 10-minute interval. This constrains the size of the emitting region to be no larger than about 20 times the size of the "event horizon" (the one-way membrane around a black hole) as predicted by Einstein's theory of relativity.
The rapid rise and fall seen by Chandra are also compelling evidence that the X-ray emission is coming from matter falling into a supermassive black hole. This would confirm the Milky Way's supermassive black hole is powered by the same accretion process as quasars and other active galactic nuclei.
Dynamical studies of the central region of our Milky Way Galaxy in infrared and radio wavelengths indicate the presence of a large, dark object, presumably a supermassive black hole having the mass of about 3 million suns. Sagittarius A* is coincident with the location of this object, and is thought to be powered by the infall of matter into the black hole. However, the faintness of Sagittarius A* at all wavelengths, especially in X-rays, has cast some doubt on this model.
The latest precise Chandra observations of the crowded galactic center region have dispelled that doubt, confirming the results of the dynamical studies. Given the extremely accurate position, it is highly unlikely that the flare is due to an unrelated contaminating source such as an X-ray binary system.

"The rapid variations in X-ray intensity indicate that we are observing material that is as close to the black hole as the Earth is to the Sun," said Gordon Garmire of Penn State University, principal investigator of Advanced CCD Imaging Spectrometer (ACIS), which was used in these observations. "It makes Sagittarius A* a uniquely valuable source for studying conditions very near a supermassive black hole."

Friday, 14 February 2014

Fusion energy: NIF experiments show initial gain in fusion fuel Feb 12, 2014

Ignition – the process of releasing fusion energy equal to or greater than the amount of energy used to confine the fuel – has long been considered the "holy grail" of inertial confinement fusion science. A key step along the path to ignition is to have "fuel gains" greater than unity, where the energy generated through fusion reactions exceeds the amount of energy deposited into the fusion fuel.

Though ignition remains the ultimate goal, the milestone of achieving 
fuel gains greater than 1 has been reached for the first time ever on any facility. In a paper published in the Feb. 12 online issue of the journal Nature, scientists at Lawrence Livermore National Laboratory (LLNL) detail a series of experiments on the National Ignition Facility (NIF), which show an order of magnitude improvement in yield performance over past experiments.
"What's really exciting is that we are seeing a steadily increasing contribution to the yield coming from the boot-strapping process we call alpha-particle self-heating as we push the implosion a little harder each time," said lead author Omar Hurricane.
Boot-strapping results when alpha particles, helium nuclei produced in the DT fusion process, deposit their energy in the deuterium-tritium (DT) fuel, rather than escaping. The alpha particles further heat the fuel, increasing the rate of fusion reactions, thus producing more alpha particles. This feedback process is the mechanism that leads to ignition. As reported in Nature, the boot-strapping process has been demonstrated in a series of experiments in which the fusion yield has been systematically increased by more than a factor of 10 over previous approaches.

The experimental series was carefully designed to avoid breakup of the plastic shell that surrounds and confines the DT fuel as it is compressed. It was hypothesized that the breakup was the source of degraded fusion yields observed in previous experiments. By modifying the laser pulse used to compress the fuel, the instability that causes break-up was suppressed. The higher yields that were obtained affirmed the hypothesis, and demonstrated the onset of boot-strapping.
The experimental results have matched computer simulations much better than previous experiments, providing an important benchmark for the models used to predict the behavior of matter under conditions similar to those generated during a nuclear explosion, a primary goal for the NIF.

The chief mission of NIF is to provide experimental insight and data for the National Nuclear Security Administration's science-based Stockpile Stewardship Program. This experiment represents an important milestone in the continuing demonstration that the stockpile can be kept safe, secure and reliable without a return to nuclear testing. Ignition physics and performance also play a key role in fundamental science, and for potential energy applications.

"There is more work to do and physics problems that need to be addressed before we get to the end," said Hurricane, "but our team is working to address all the challenges, and that's what a scientific team thrives on."

Monday, 10 February 2014


I opine that, if not wrong

I have done some basic work [up to 2nd step] on Dark energy & Dark Matter. On the basis of which I can explain lots of things like 
1. REASON OF GRAVITY - explained how unification of dark energy explained reason of tide, reason of higher force on other side of moon, reason of expansion of universe.why depression of space time is not the reason of gravity?why gravity is more near the surface? [abstract in]-this abstract was sent to "General Relativity and Gravitation" on 15th, Aug'2013
2. where Dark Atom & Dark Energies are produce?, how they interact with white matter?, why & how they move?, how matter is converted into energy & energy into matter? how baryons are buried in nucleus? why electrons are moving around? why semiconductor conduct at very low temperature? why the position of electrons are uncertain?

3. why Dark Atom & Dark Energy are not detectable? why we see it easily near the core of the galaxy? where we have to hunt for dark energy & dark matter? is only white atom [visible atoms] comes out when we pour water in a bottle? why an solid remain in the shape? 
4, how solar system evolved? why life evolved in earth itself? how & where stars have been forming? why van allen belt form? from where electron, proton, neutron etc are coming from? how galaxy & black hole are forming?[ ] why heavy metals come out first during supernova blast?[ ] how kuiper belt & asteroid belt are formed?why the oort cloud sending visitors in our solar system?

And many
many more?

I have hard copy of my work & some of the brief comment is also in different physical magazine, journals, blogs, etc [few links are given in my blog itself]

I want your help in cross checking my hypothesis.

Saturday, 8 February 2014

"Dark Matter Might Not Exist" (Weekend Feature) - 8th, Feb.'2014

This past 4th of July 2013, a European team of astronomers led by Hongsheng Zhao of the SUPA Centre of Gravity at the University of St Andrews presented a radical new theory at the RAS National Astronomy Meeting in St Andrews. Their theory suggested that the Milky Way and Anromeda galaxies collided some 10 billion years ago and that our understanding of gravity is fundamentally wrong. Remarkably, this would neatly explain the observed structure of the two galaxies and their satellites.
In 2009, Zhao led An international team of astronomers that found an unexpected link between 'dark matter' and the visible stars and gas in galaxies that could revolutionize our current understanding of gravity. Zhao suggested that an unknown force is acting on dark matter.The team believes that the interactions between dark and ordinary matter could be more important and more complex than previously thought, and even speculate that dark matter might not exist and that the anomalous motions of stars in galaxies are due to a modification of gravity on extragalactic scales.
"The dark matter seems to 'know' how the visible matter is distributed. They seem to conspire with each other such that the gravity of the visible matter at the characteristic radius of the dark halo is always the same," said Dr. Benoit Famaey (Universities of Bonn and Strasbourg). "This is extremely surprising since one would rather expect the balance between visible and dark matter to strongly depend on the individual history of each galaxy.
"The pattern that the data reveal is extremely odd. It's like finding a zoo of animals of all ages and sizes miraculously having identical, say, weight in their backbones or something. It is possible that a non-gravitational fifth force is ruling the dark matter with an invisible hand, leaving the same fingerprints on all galaxies, irrespective of their ages, shapes and sizes."
Such a force might solve an even bigger mystery, known as 'dark energy', which is ruling the accelerated expansion of the Universe. A more radical solution is a revision of the laws of gravity first developed by Isaac Newton in 1687 and refined by Albert Einstein's theory of General Relativity in 1916. Einstein never fully decided whether his equation should add an omnipresent constant source, now called dark energy. Astrophyisicts Neil Degrasse Tyson has stated that dark energy soould in fact be renamed dark gravity.
In the image above above dark energy is represented by the purple grid above, and gravity by the green grid below. Gravity emanates from all matter in the universe, but its effects are localized and drop off quickly over large distances. 
Dr Famaey added, "If we account for our observations with a modified law of gravity, it makes perfect sense to replace the effective action of hypothetical dark matter with a force closely related to the distribution of visible matter."
The implications of the new research could change some of the most widely held scientific theories about the history and expansion of the universe.
Lead researcher Dr. Gianfranco Gentile at the University of Ghent concluded, "Understanding this puzzling conspiracy is probably the key to unlock the formation of galaxies and their structures."
In January 2010, Erik Verlinde, professor ofTheoretical Physics and world-renowned string theorist, caused a worldwide stir with the publication of On the Origin of Gravity and the Laws of Newton, in which he challenged commonly held perceptions on gravity, going so far as to state ‘for me gravity doesn’t exist’. If he is proved correct, the consequences for our understanding of the universe and its origins in a Big Bang will be far-reaching.
"Everyone who is working on theoretical physics is trying to improve on Einstein," says Robbert Dijkgraaf, UvA University Professor and current director of the Institute for Advanced Study in Princeton (where scientists including Turing, Oppenheimer and Einstein have worked) In my opinion, Erik Verlinde has found an important key for the next step forward."
Verlinde, who received the Spinoza prize (the Dutch Nobel Prize) from the Netherlands Organisation for Science, is famous for developing this new theory, or idea, on gravity in which he says that gravity is an illusion. "Gravity is not an illusion in the sense that we know that things fall," says Verline." Most people, certainly in physics, think we can describe gravity perfectly adequately using Einstein’s General Relativity. But it now seems that we can also start from a microscopic formulation where there is no gravity to begin with, but you can derive it. This is called ‘emergence’."
"We have other phenomena in Physics like this," Verlinde continued. "Take a concept like ‘temperature’, for instance. We experience it every day. We can feel temperature. But, if you really think about the microscopic molecules, there’s no notion of temperature there. It’s something that has to do with the property of all molecules together; it’s like the average energy per molecule."
To Verlinde, gravity is similar. It’s something that only appears when you put many things together at a microscopic scale and then you suddenly see that certain equations arise. "As scientists," he observes, "we first want to understand nature and our universe. In doing so, we have observed things that are deeply puzzling, such as phenomena related to dark matter. We see things happening that we don’t understand. There must be more matter out there that we don’t see. There’s also something called ‘dark energy’. And then there’s the whole puzzle of the beginning of the universe. We now have what is called the ‘Big Bang’ theory.
Verline belives his ideas will shed new light on the concept of ‘dark matter’ and ‘dark energy’ and why they’re important in relation to gravity.
"We think we understand gravity in most situations," he says "but when we look at galaxies and, on much larger scales, at galaxy clusters, we see things happening that we don’t understand using our familiar equations, like Newton’s equation of gravity or even Einstein’s gravity. So we have to assume there’s this mysterious form of matter, which we call dark matter, which we cannot see. Now dark energy is even weirder, in the sense that we don’t even know what it consists of. It’s something we can put in our equations to make things work, but there’s really a big puzzle to be solved in terms of why it’s there and what it’s made of. At present, we have not really found the right equations to describe it. There’s clearly progress to be made in terms of finding a bettertheory of gravity, and understanding what’s happening in our universe."
For example, the Big Bang theory is the idea that at a particular moment things suddenly started exploding and growing, and that our universe got bigger, which Verlinde finds illogical to think it came from this one moment.
"It’s illogical to think there was nothing and then it exploded. We use concepts like time and space," he adds, "but we don’t really understand what this means microscopically. That might change. The Big Bang has to do with our understanding of what time should be, and I think we will have a much better understanding of this in the future. I think we will figure out that what we thought was the Big Bang was actually a different kind of event. Or maybe that we should not think that the universe really began at a particular moment and that there’s another way to describe that."
Verlinde believes that the information we have today and the equations we now use only describe a very small part of what is actually going on. "If you think that something grows, like our universe, than something else must become smaller," he observes."I think there’s something we haven’t found yet and this will help us discover the origins of our universe. In short, the universe originated from something, not from nothing. There was something there and we have to find the equations. It has something to do with dark energy and how that is related to dark matter. If we understand the equations for those components of our universe, I think we’ll also have a better understanding of how the universe began. I think it’s all about the interplay between these different forms of energy and matter.
The Big Bang theory works well in the sense that it gives us some understanding of how particular elements in our universe came about and there are other things that we can observe, like the radiation that came from the Big Bang. But the whole idea of an expanding universe that started with a big explosion will change. "You need to think about the equations in a bigger setting," Verlinde observes. "You need to describe more than just the matter particles. You need to know more about what space/time is. All these things have to come together in order to be able to explain the Big Bang."
Quantum mechanics took approximately 26 years to develop, Verlinde concludes. "We’ve had string theory for 40 years and nothing yet has come out of that which can be directly tested with observations or experiments. I think my idea has a greater chance of being tested with observations, which is an exciting thing. I think it will take no more than 10 or 15 years."
The end result be belives will lead to a paradigm shift in how people think that the universe was created.

Journal Reference: Gianfranco Gentile, Benoit Famaey, HongSheng Zhao, Paolo Salucci. Universality of galactic surface densities within one dark halo scale-length. Nature, 2009; 461 (7264): 627 DOI: 10.1038/nature08437

Thursday, 6 February 2014

Early universe 'warmed up' later than previously believed, study finds - Feb 05, 2014

A new study from Tel Aviv University reveals that black holes, formed from the first stars in our universe, heated the gas throughout space later than previously thought. They also imprinted a clear signature in radio waves which astronomers can now search for. The work is a major new finding about the origins of the universe.
"One of the exciting frontiers in astronomy is the era of the formation of the first stars," explains Prof. Rennan Barkana of TAU's School of Physics and Astronomy, an author of the study. "Since the universe was filled with hydrogen atoms at that time, the most promising method for observing the epoch of the first stars is by measuring the emission of hydrogen using radio waves."
The study, just published in the journal Nature, was co-authored by Dr. Anastasia Fialkov of TAU and the École Normale Supérieure in Paris and Dr. Eli Visbal of Columbia and Harvard Universities.
Cosmic archaeology
Astronomers explore our distant past, billions of years back in time. Unlike Earth-bound archaeologists, however, who can only study remnants of the past, astronomers can see the past directly. The light from distant objects takes a long time to reach the earth, and astronomers can see these objects as they were back when that light was emitted. This means that if astronomers look out far enough, they can see the first stars as they actually were in the early universe. Thus, the new finding that cosmic heating occurred later than previously thought means that observers do not have to search as far, and it will be easier to see this cosmic milestone.
Cosmic heating may offer a way to directly investigate the earliest black holes, since it was likely driven by star systems called "black-hole binaries." These are pairs of stars in which the larger star ended its life with a supernova explosion that left a black-hole remnant in its place. Gas from the companion star is pulled in towards the black hole, gets ripped apart in the strong gravity, and emits high-energy X-ray radiation. This radiation reaches large distances, and is believed to have re-heated the cosmic gas, after it had cooled down as a result of the original cosmic expansion. The discovery in the new research is the delay of this heating.
The cosmic radio show
"It was previously believed that the heating occurred very early," says Prof. Barkana, "but we discovered that this standard picture delicately depends on the precise energy with which the X-rays come out. Taking into account up-to-date observations of nearby black-hole binaries changes the expectations for the history of cosmic heating. It results in a new prediction of an early time (when the universe was only 400 million years old) at which the sky was uniformly filled with radio waves emitted by the hydrogen gas."

In order to detect the expected radio waves from hydrogen in the early universe, several large international groups have built and begun operating new arrays of radio telescopes. These arrays were designed under the assumption that cosmic heating occurred too early to see, so instead the arrays can only search for a later cosmic event, in which radiation from stars broke up the hydrogen atoms out in the space in-between galaxies. The new discovery overturns the common view and implies that these radio telescopes may also detect the tell-tale signs of cosmic heating by the earliest black holes.