Astrophysicist

A major problem arose in 1925 when an extraordinary star was discovered. Although it was as massive as Sun, it was only as big as the Earth! This meant that the average density of the star was about 10^6 g.cm^-3 (the mean density of the Sun is only a little more than that of water). The difficulty posed by such a dense star was the following. What will happen to such a star when nuclear energy generation at its center stops? Since the star will no longer produce heat, there will be no force to oppose gravity. What will be the end state of such a star? Surprisingly, the resolution of this problem came from the newly emerging Quantum Physics. In 1926, R. H. Fowler at Cambridge University argued that the star will collapse and collapse till it reaches a density where a new quantum mechanical force provides support against gravity, and the star will at last find peace. This quantum pressure is due to the electrons and arises due to the combination effect of Heisenberg`s principle of

As already mentioned( https://forastrophysicist.blogspot.com/2019/08/the-revolution-that-was-unfolding-at.html?m=1 ), Fraunhofer`s discovery of dark lines in the spectrum of the Sun enabled the physicists to conclude that the Sun`s outer layers were gaseous. By 1870, the Sun and the stars had been modelled as spheres, held together by their own gravity. The outstanding question at the turn of the nineteenth century was the following: what is the source of energy that makes the star shine? In 1920, Sir Arthur Eddington at Cambridge University in England made the extraordinary suggestion that the source of energy was the transmutation of hydrogen into helium at the center of the stars. He went on to construct a detailed theory of the stars based upon the simple principle that the inward-directed force due to self-Gravity was balanced by the combined pressure of the gas and radiation, both of which are directed outwards. Despite its simplicity, many predictions of this theory were i

A diagram of the structure of the  maximally extended black hole   spacetime. The horizontal direction is space and the vertical direction is time. The equations of General relativity have an interesting mathematical property: they are symmetric in time. That means that you can take any solution to the equations and imagine that time flows backwards rather than forwards, and you will get another valid solution to the equations. If you apply this rule to the solution that describes Black Holes, you get an object known as White Hole. Since a Black Hole is a region of space from which nothing can escape not even light the Time-Reversed version of a Black Hole is a region of space into which nothing can fall. In fact, just as a Black Hole can only suck things in, a White Hole can only spit things out. White holes are a perfectly valid mathematical solution to the equations of General relativity, but that does not mean that they actually exist in nature. In fact they almost ce

Well, first, let me assure you that the Sun has no intention of doing any such thing. Only Stars that weigh considerably more than the Sun end their lives as Black Holes. The Sun is going to stay roughly the way it is for another five billion years or so. Then it will go through a brief phase as a red giant Star. During which time it will expand to engulf the planets Mercury and Venus and make life quite uncomfortable on Earth (oceans boiling, atmosphere escaping, that sort of things). After that, the Sun will end its life by becoming a boring White Dwarf Star. If I were you, I do make plans to move somewhere far away before any of this happens. But I digress. What if the sun did become a Black Hole for some reason? The main effect is that it would get very dark and very cold around here. The earth and the others planets would not get sucked into the Black Hole; they would keep on orbiting in exactly the same paths they follow right now. Why? Because the horizon of this Blac

         There are at least two different ways to describe how big something is. We can say how much mass it has, or we can say how much space it takes up. Let's talk first about the masses of Black Holes.          There is no limit in principle to how much or how little mass a Black Hole can have. Any amount of mass at all can in principle be made to form a Black Hole if you compress it to a high enough density. We suspect that most of the Black Holes that are actually out there were produced in the deaths of massive Stars, and so we expect those Black Holes to weigh about as much as a massive Star. A typical mass for such a Stellar Black hole would be about 10 times the mass of the Sun, or about 10^31 kilograms. Astronomers also suspect that many Galaxies harbor extremely massive Black Holes at their centers. These are thought to weigh about a million times as much as the Sun, or 10^36 kilograms.          The more massive Black Hole is, the more space it takes

    The Hubble Space Telescope is a NASA space telescope that was carried into orbit by a space shuttle named Discovery (STS-31) on 24th April 1990. It was carried in the shuttle`s cargo bay! The space based observatory allows astronomers a better view of the Universe. The telescope is the size of a school bus.     Hubble is one of the largest and most versatile, and is well known as both a vital research tool and a public relations boon for astronomy. The HST was built by the United States Space Agency NASA, with contributions from the European Space Agency, and is operated by the Space Telescope Science Institute, Baltomore, MD.     NASA named the world`s first space based optical telescope after American astronomer Edwin P. Hubble (1889-1953). In 1929 A.D, Edwin Hubble confirmed an expanding universe, which provided the foundation for the Big Bang theory.     Hubble is the only telescope ever designed to be servicing missions were performed from 1993-2002, but fifth was ca

1. It's craters have been untouched by sunlight for billions of years- offering an undisturbed record of the solar system's origin. 2. It's permanently shadowed craters are estimated to hold 100 million tons of water. 3. It's regolith has traces of hydrogen, ammonia, methane, sodium, mercury and silver-making it an untapped source of essential resources. 4. It's elemental and positional advantages make it a suitable pit stop for future space exploration. Source - https://mobile.twitter.com/isro/status/1162752450903678978 Also see - https://forastrophysicist.blogspot.com/2019/08/chandrayaan-2.html?m=1 To see Chadrayaan mission click here 👇👇👇👇👇👇👇👇 https://youtu.be/QSd2OLEcrUA #Ankistar

Suppose you lose your baseball in the woods, and you and your friend decide to look for it. You know that either you will find it, or your friend will (or it will remain lost). Assuming the ball hasn’t been damaged, it won’t be the case that you and your friend each find half of the ball, or that you both find the ball in different locations. There is only one ball, and it has an exact location, even if you don’t know where it is. It can only be found once, and only by one of you. A wave behaves differently, however. Suppose the ball is dropped into the center of a pond, and you and your friend stand on the shore to look for the wave. You can be on one side of the pond, your friend on the other side, and you can both see the wave wash upon the shore. You can even both see the wave wash ashore at the same time, because part of the wave is near you, while another part is near your friend. This is a fundamental difference between particles and waves. Particles are local, with a

"The revolution that was unfolding at the dawn of twentieth century concerned the nature of stars. According to the positivist philosophers who greatly influenced European thinking in the eighteenth and nineteenth century, it was in the nature of things that we shall never know what the stars are. The discovery of the dark lines in the spectrum of the Sun and the stars by Joseph V. Fraunhofer IN 1817 AND their subsequent explanation by Gustav Kirchoff, Bunsen and others, proved the philosophers wrong. It was clear that at least the outer layers of the Sun was gaseous and made of the same atom that we find on the Earth. The subject of Astrophysics born. By the 1930s one had understood a great deal about what are the Stars and why are they as they are. And the new journey begins."                                                                          #Ankistar

Chandrayaan-2, India’s second mission to the moon, will comprise an orbiter, a lander named Vikram [after the father of Indian space programme Vikram Sarabhai], and a rover.   It was supposed to be launched on  15 July 2019 at 2:51 IST (14 July 2019 21:21 UTC) but was called off due to a technical snag noticed while filling the cryogenic engine of the rocket with helium   about one hour before launch.  So  the mission was postponed. The landing site for the Chandrayaan-2 rover is expected to be between the two craters Manzinus C and Simpelius N near the southern pole of the moon. The orbiter will go around the moon at an altitude of 100 km, acting as a communication relay between the lander/rover and Earth. The far side of the moon can never be in direct line-of-sight with Earth, proving direct radio communication impossible, which is why the orbiter is needed. It will carry five instruments: A radar that will probe a few metres below the surface to detect water ic

We all know and love the Higgs boson — which to physicists' chagrin has been mistakenly tagged in the media as the "God particle" — a subatomic particle first spotted in the Large Hadron Collider (LHC) back in 2012. That particle is a piece of a field that permeates all of space-time; it interacts with many particles, like electrons and quarks, providing those particles with mass, which is pretty cool. But the Higgs that we spotted was surprisingly lightweight. According to our best estimates, it should have been a lot heavier. This opens up an interesting question: Sure, we spotted a Higgs boson, but was that the only Higgs boson? Are there more floating around out there doing their own things? Though we don't have any evidence yet of a heavier Higgs, a team of researchers based at the LHC, the world's largest atom smasher, is digging into that question as we speak. And there's talk that as protons are smashed together inside the ring-shaped c

It all depends on what you call mass. Mass, as it appears in classical non relativistic case is the measure of material that is contained in the particle. That is one aspect. Mass is the one which appears the force acceleration equation. Larger the mass, lesser the acceleration for the same force. Mass is the one which decides gravitational attraction between two particles at a given distance. Generally, we take our definition of mass from Force-acceleration relations. This mass is also called Rest mass. Please note that this mass does not change as the particle gains speed.  Very interestingly, the material can be converted into energy. Once that happens material disappears and the mass is lost. The relation is E = mc^2.  People also define mass from this relation E = mc^2. The energy of a particle is E, its "so called" mass is E/c^2. This is very different from the mass that we know from force-acceleration relations. The name given is relativistic mass. In fact, we do no