Blackholes : II

Black holes are the cold remnants of former stars, so dense that no matter—not even light—is able to escape their powerful gravitational pull.

While most stars end up as white dwarfs* or neutron stars*, black holes are the last evolutionary stage in the lifetimes of enormous stars that had been at least 10 or 15 times as massive as our own sun.

When giant stars reach the final stages of their lives they often detonate in cataclysms known as supernovae*. Such an explosion scatters most of a star into the void of space but leaves behind a large "cold" remnant on which fusion no longer takes place.

In younger stars, nuclear fusion creates energy and a constant outward pressure that exists in balance with the inward pull of gravity caused by the star's own mass. But in the dead remnants of a massive supernova, no force opposes gravity—so the star begins to collapse in upon itself.

With no force to check gravity, a budding black hole shrinks to zero volume—at which point it is infinitely dense. Even the light from such a star is unable to escape its immense gravitational pull. The star's own light becomes trapped in orbit, and the dark star becomes known as a black hole.

Black holes pull matter and even energy into themselves—but no more so than other stars or cosmic objects of similar mass. That means that a black hole with the mass of our own sun would not "suck" objects into it any more than our own sun does with its own gravitational pull.

Planets, light, and other matter must pass close to a black hole in order to be pulled into its grasp. When they reach a point of no return they are said to have entered the event horizon*—the point from which any escape is impossible because it requires moving faster than the speed of light.

                                             

Small But Powerful

Black holes are small in size. A million-solar-mass hole, like that believed to be at the center of some galaxies, would have a radius of just about two million miles (three million kilometers)—only about four times the size of the sun. A black hole with a mass equal to that of the sun would have a two-mile (three-kilometer) radius.

Because they are so small, distant, and dark, black holes cannot be directly observed. Yet scientists have confirmed their long-held suspicions that they exist. This is typically done by measuring mass in a region of the sky and looking for areas of large, dark mass.

Many black holes exist in binary star systems*. These holes may continually pull mass from their neighboring star, growing the black hole and shrinking the other star, until the black hole is large and the companion star has completely vanished.

Extremely large black holes may exist at the center of some galaxies—including our own Milky Way. These massive features may have the mass of 10 to 100 billion suns. They are similar to smaller black holes but grow to enormous size because there is so much matter in the center of the galaxy for them to add. Black holes can accrue limitless amounts of matter; they simply become even denser as their mass increases.

Black holes capture the public's imagination and feature prominently in extremely theoretical concepts like wormholes*. These "tunnels" could allow rapid travel through space and time—but there is no evidence that they exist.

Dictionary:

        White Dwarfs:

   Remnants of low-mass stars

   Supported by Electron Degeneracy Pressure

   Maximum Mass ~1.4 M_sun (Chandrasekhar Mass)

         Neutron Stars:

   Remnants of some post-supernova massive stars

   Supported by Neutron Degeneracy Pressure

   Pulsar = rapidly spinning magnetized neutron star

Supernovae:

    Supernovae are exploding stars. They represent the very final stages of evolution     for some stars.

   10²⁰ times as much energy produced in the supernova explosion.

Binary Star System:

    A binary system is a system of two objects in space (usually stars, but also brown    dwarfs, planets,     galaxies, or asteroids) which are so close that their gravitational interaction causes them to orbit               about a common center of mass

Event Horizon:

   A notional boundary around a black hole beyond which no light or other radiation can escape.

Wormholes:

   A hypothetical connection between widely separated regions of space–time.

Source: NatGeo

Blackholes: I

A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a
star is dying.

Because no light can get out, people can't see black holes, hence the name blackholes.

How Big Are Black Holes?

Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount
of matter, or "stuff," in an object.

Another kind of black hole is called "stellar."Its mass can be up to 20 times more than the mass
of the sun. There may be many, many stellar mass black holes in Earth's galaxy. Earth's galaxy is called the Milky Way.

The largest black holes are called "supermassive." These black holes have masses that are more
than 1 million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its center. The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.


If Black Holes Are "Black," How Do Scientists Know They Are There?

A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole.
Scientists can study stars to find out if they are flying around, or orbiting, a black hole.

When a black hole and a star are close together, high-energy light is made. This kind of light
can not be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light.

But the great physicist, Stephen Hawking begs to differ as he said that light has no mass and can
escape the strong pull of a black hole.

So who knows black holes may not be black(dark) after all.

Could a Black Hole Destroy Earth?

Black holes do not go around in space eating stars, moons and planets. Earth will not fall into
a black hole because no black hole is close enough to the solar system for Earth to do that. Even
if a black hole the same mass as the sun were to take the place of the sun, Earth still would not
fall in. The black hole would have the same gravity as the sun. Earth and the other planets would orbit the black hole as they orbit the sun now.

The sun will never turn into a black hole. The sun is not a big enough star to make a black hole.

So for now we can just be safe that our little planet called 'Earth' aka our home is safe.

Antimatter

A wise man once said, "To every action,there is an equal and opposite reaction." So is with the matter. There is a flip side of the matter i.e. Antimatter. 

Okay now, consider an equation  x2=4  which might have two probable solutions : x = 2 or x = -2. So, according to the British physicist Paul Dirac's theory there could be electron with positive or with negative energy. But classical physics (and common sense) dictated that the energy of a particle must always be a positive number.

Dirac interpreted the equation to mean that for every particle there exists a corresponding antiparticle, exactly matching the particle but with opposite charge. For the electron there should be an "anti-electron", for example, identical in every way but with a positive electric charge. The insight opened the possibility of entire galaxies and universes made of antimatter.

But when matter and antimatter come into contact, they annihilate – disappearing in a flash of energy. The big bang should have created equal amounts of matter and antimatter. So why is there far more matter than antimatter in the universe?

Antimatter is the stuff of science fiction. In the book and film Angels and Demons, Professor Langdon tries to save Vatican City from an antimatter bomb. Star Trek’s starship Enterprise uses matter-antimatter annihilation propulsion for faster-than-light travel.

But antimatter is also the stuff of reality. Antimatter particles are almost identical to their matter counterparts except that they carry the opposite charge and spin. When antimatter meets matter, they immediately annihilate into energy.

While antimatter bombs and antimatter-powered spaceships are far-fetched, there are still many facts about antimatter that will tickle your brain cells.

 Antimatter is closer to you than you think.

Small amounts of antimatter constantly rain down on the Earth in the form of cosmic rays, energetic particles from space. These antimatter particles reach our atmosphere at a rate ranging from less than one per square meter to more than 100 per square meter. Scientists have also seen evidence of antimatter production above thunderstorms.

But other antimatter sources are even closer to home. For example,bananas produce antimatter, releasing one positron—the antimatter equivalent of an electron—about every 75 minutes. This occurs because bananas contain a small amount of potassium-40, a naturally occurring isotope of potassium. As potassium-40 decays, it occasionally spits out a positron in the process.

Our bodies also contain potassium-40, which means positrons are being emitted from you, too. Antimatter annihilates immediately on contact with matter, so these antimatter particles are very short-lived.



Well Antimatter is nothing like pure energy or something.

But,

If antimatter and matter are exactly equal but opposite, then why is there so much more matter in the universe than antimatter?

Well... we don't know. It is a question that keeps physicists up at night. 

And our quest for the knowledge continues.

Adios!

The infamous enigmas.

This world is an enigma, yet to be solved. And so are the many unsolved problems in many different fields. Among them is the infamous mathematics (and computer science) problem P vs. NP.

P vs. NP is a millennium prize problem. The first being providing even the nearest correct solution would be awarded US$ 1,000,000.

What is P vs. NP?

Well P vs. NP is the name of a problem that many mathematicians, scientists and computer programmers want to answer. P and NP are the two groups of the mathematics problems. P problems are generally considered “easy” for a computer to solve, whereas NP problems are easy for a computer to check.

Now, you have a NP problem and say the solution to your problem is ‘I N F O’, a computer can figure out in a beat if the solution is correct or not, but it may take like forever for a computer to come up with ‘I N F O’ on its own.

The ‘P versus NP’ asks whether these two classes of problems are actually identical; i.e. whether every NP problem is also a P problem. If P=NP, every NP problem would contain a hidden shortcut which a computer can find in a reasonable amount of time. But if not, then a computer’s ability to solve problems remains fundamentally and potentially limited.

If P=NP…….

If the above stated would be true (which isn’t), it would bring something like second industrial revolution. It would completely revolutionize the world we live in.

There would be a short program which, given detailed constraints on any engineering task, would quickly generate a design which meets the given criteria, if one exists.

And there would be a short program which, given data on some phenomena and modeling restrictions, would quickly generate a theory to explain that data within the modeling constraints, if one exists. Many things that scientists hope to explain, like about how the brain works, the nature of dark matter and dark energy, the structure and function of proteins, etc. could potentially be done in a wink!

But we live in the real world, not in the utopia described above. And in here P is not equal to NP.

Not the End!

So we can see P vs. NP as, for students it is easier to understand a lecture than to come up with the matter for one from scratch on their own.

Now as for me, I’m just another curious homo sapien on his quest for knowledge, which for humans can never end. And we’ve only just begun! Let us advance ahead and unwind the enigma behind this code.

Look Up

Mars gets 'MOM' : India creates history

New Delhi: Creating history in space, India on September 24, 2014, Wednesday successfully placed its Mangalyaan into the Martian orbit.

Thus, India became the first Asian country to reach Mars and the first in the world to enter Martian orbit in its maiden attempt.

With the success of MOM, India now joins the United States, European Space Agency and the former Soviet Union in the elite club of Martian explorers.

According to ISRO, the Mars spacecraft was successfully inserted into the Martian orbit at 515 km away from the red planet's surface and 215 million km away from the earth in radio distance.

The challenging task of the Mars orbit insertion began in the early hours of Wednesday at 4.17 a.m. when the spacecraft switched over to the medium gain antenna for emitting and receiving radio signals.