Subatomic particles are particles that are smaller than an atom. In 1940, the number of subatomic particles known to science could be counted on the fingers of one hand: protons, neutrons, electrons, neutrinos, and positrons. The first three particles were known to be the building blocks from which atoms are made: protons and neutrons in atomic nuclei and electrons in orbit around those nuclei. Neutrinos and positrons were somewhat peculiar particles discovered outside Earth's atmosphere and of uncertain origin or significance.
That view of matter changed dramatically over the next two decades. With the invention of particle accelerators (atom-smashers) and the discovery of nuclear fission and fusion, the number of known subatomic particles increased. Scientists discovered a number of particles that exist at energies higher than those normally observed in our everyday lives: sigma particles, lambda particles, delta particles, epsilon particles, and other particles in positive, negative, and neutral forms. By the end of the 1950s, so many subatomic particles had been discovered that some physicists referred to their list as a "particle zoo."

The quark model

In 1964, American physicist Murray Gell-Mann (1929– ) and Swiss physicist George Zweig (1937– ) independently suggested a way out of the particle zoo. They suggested that the nearly 100 subatomic particles that had been discovered so far were not really elementary (fundamental) particles. Instead, they suggested that only a relatively few elementary particles existed, and the other subatomic particles that had been discovered were composed of various combinations of these truly elementary particles.

Words to Know

Antiparticles: Subatomic particles similar to the proton, neutron, electron, and other subatomic particles, but having one property (such as electric charge) opposite them.

Atomic mass unit (amu): A unit of mass measurement for small particles.

Atomic number: The number of protons in the nucleus of an atom.

Elementary particle: A subatomic particle that cannot be broken down into any simpler particle.

Energy levels: The regions in an atom in which electrons are most likely to be found.

Gluon: The elementary particle thought to be responsible for carrying the strong force (which binds together neutrons and protons in the atomic nucleus).

Graviton: The elementary particle thought to be responsible for carrying the gravitational force.

Isotopes: Forms of an element in which atoms have the same number of protons but different numbers of neutrons.

Lepton: A type of elementary particle.

Photon: An elementary particle that carries electromagnetic force.

Quark: A type of elementary particle

Spin: A fundamental property of all subatomic particles corresponding to their rotation on their axes.
The truly elementary particles were given the names quarks and leptons. Each group of particles, in turn, consists of six different types of particles. The six quarks, for example, were given the rather fanciful names of up, down, charm, strange, top (or truth), and bottom (or beauty). These six quarks could be combined, according to Gell-Mann and Zweig, to produce particles such as the proton (two up quarks and one down quark) and the neutron (one up quark and two down quarks).
In addition to quarks and leptons, scientists hypothesized the existence of certain particles that "carry" various kinds of forces. One of those particles was already well known, the photon. The photon is a strange type of particle with no mass that apparently is responsible for the transmission of electromagnetic energy from one place to another.
In the 1980s, three other force-carrying particles were also discovered: the W + , W , and Z 0 bosons. These particles carry certain forces that can be observed during the radioactive decay of matter. (Radioactive elements spontaneously emit energy in the form of particles or waves by disintegration of their atomic nuclei.) Scientists have hypothesized the existence of two other force-carrying particles, one that carries the strong force, the gluon (which binds together protons and neutrons in the nucleus), and one that carries gravitational force, the graviton.

Five important subatomic particles

For most beginning science students, the five most important sub-atomic particles are the PROTON, NEUTRON, ELECTRON, NEUTRINO, and POSITRON. Each of these particles can be described completely by its mass, electric charge, and spin. Because the mass of subatomic particles is so small, it is usually not measured in ounces or grams but in atomic mass units (label: amu) or electron volts (label: eV). An atomic mass unit is approximately equal to the mass of a proton or neutron. An electron volt is actually a unit of energy but can be used to measure mass because of the relationship between mass and energy (E = mc 2 ).

                                                   All subatomic particles (indeed, all particles) can have one of three electric charges: positive, negative, or none (neutral). All subatomic particles also have a property known as spin, meaning that they rotate on their axes in much the same way that planets such as Earth do. In general, the spin of a subatomic particle can be clockwise or counterclockwise, although the details of particle spin can become quite complex.

PROTON:The proton is a positively charged subatomic particle with an atomic mass of about 1 amu. Protons are one of the fundamental constituents of all atoms. Along with neutrons, they are found in a very concentrated region of space within atoms referred to as the nucleus.The number of protons determines the chemical identity of an atom. This property is so important that it is given a special name: the atomic number. Each element in the periodic table has a unique number of protons in its nucleus and, hence, a unique atomic number.

NEUTRON. A neutron has a mass of about 1 amu and no electric charge. It is found in the nuclei of atoms along with protons. The neutron is normally a stable particle in that it can remain unchanged within the nucleus for an infinite period of time. Under some circumstances, however, a neutron can undergo spontaneous decay, breaking apart into a proton and an electron. When not contained with an atomic nucleus, the half-life for this change—the time required for half of any sample of neutrons to undergo decay—is about 11 minutes.
The nuclei of all atoms with the exception of the hydrogen-1 isotope contain neutrons. The nuclei of atoms of any one element may contain different numbers of neutrons. For example, the element carbon is made of at least three different kinds of atoms. The nuclei of all three kinds of atoms contain six protons. But some nuclei contain six neutrons, others contain seven neutrons, and still others contain eight neutrons. These forms of an element that contain the same number of protons but different numbers of neutrons are known as isotopes of the element.
Electron. Electrons are particles carrying a single unit of negative electricity with a mass of about 1/1800 amu, or 0.0055 amu. All atoms contain one or more electrons located in the space outside the atomic nucleus. Electrons are arranged in specific regions of the atom known as energy levels. Each energy level in an atom may contain some maximum number of electrons, ranging from a minimum of two to a maximum of eight.

ELECTRONS AND LEPTONS: Unlike protons and neutrons, they are not thought to consist of any smaller particles but are regarded themselves as elementary particles that cannot be broken down into anything simpler.
All electrical phenomena are caused by the existence or absence of electrons or by their movement through a material.

Properties of the Leptons

Rest mass
0(<7 x 10-6)

NEUTRINO. Neutrinos are elusive subatomic particles that are created by some of the most basic physical processes of the universe, like decay of radioactive elements and fusion reactions that power the Sun. They were originally hypothesized in 1930 by Swiss physicist Wolfgang Pauli (1900–1958). Pauli was trying to find a way to explain the apparent loss of energy that occurs during certain nuclear reactions.
Neutrinos ("little neutrons") proved very difficult to actually find in nature, however. They have no electrical charge and possibly no mass. They rarely interact with other matter. They can penetrate nearly any form of matter by sliding through the spaces between atoms. Because of these properties, neutrinos escaped detection for 25 years after Pauli's prediction.
Then, in 1956, American physicists Frederick Reines and Clyde Cowan succeeded in detecting neutrinos produced by the nuclear reactors at the Savannah River Reactor. By 1962, the particle accelerator at Brookhaven National Laboratory was generating enough neutrinos to conduct an experiment on their properties. Later, physicists discovered a second type of neutrino, the muon neutrino.
Traditionally, scientists have thought that neutrinos have zero mass because no experiment has ever detected mass. If neutrinos do have a mass, it must be less than about one hundred-millionth the mass of the proton, the sensitivity limit of the experiments. Experiments conducted during late 1994 at Los Alamos National Laboratory hinted at the possibility that neutrinos do have a very small, but nonzero, mass. Then in 1998, Japanese researchers found evidence that neutrinos have at least a small mass, but their experiments did not allow them to determine the exact value for the mass.
In 2000, at the Fermi National Accelerator Laboratory near Chicago, a team of 54 physicists from the United States, Japan, South Korea, and

Electronic display of energies from subatomic particles. (Reproduced by permission of Photo Researchers, Inc.)

Electronic display of energies from subatomic particles. (Reproduced by permission of
Photo Researchers, Inc.

Greece detected a third type of neutrino, the tau neutrino, considered to be the most elusive member of the neutrino family.

POSITRON. A positron is a subatomic particle identical in every way to an electron except for its electric charge. It carries a single unit of positive electricity rather than a single unit of negative electricity.
The positron was hypothesized in the late 1900s by English physicist Paul Dirac (1902–1984) and was first observed by American physicist Carl Anderson (1905–1991) in a cosmic ray shower. The positron was the first antiparticle discovered—the first particle that has properties similar to protons, neutrons, and electrons, but with one property exactly the opposite of them.


According to "STRING THEORY" - a relatively new theory which attempts to combine all the forces known to physics in a single unified WHOLE - there may be any number of universes in existence. However, each of them might be governed by different natural laws. For this reason most of these universes could not sustain life, since to find a combination of natural laws that would allow life to exist would be exceptional.

                              However rare such a combination may be, any universe containing an intelligent observer would inevitably be an exceptional universe of this kind. Some scientists this is one way of explaining why it is that the natural laws in our universe seem designed to allow life to exist - because we are here to observe it. Or it may be merely a matter of chance that this is how it is. 



Only the astronomer's professional organization, the "INTERNATIONAL ASTRONOMICAL UNION"(IAU) can decide on names, & there are strict rules surrounding the naming of celestial bodies.For example, comets are always named after their discoverer.In the case of asteroids, the discoverer is entitled to suggest a name but it must be approved by a committee of the IAU. These days, most stars are merely given a catalogue number which usually contains a set of celestial coordinates indicating the body's position in the sky. 

 for more info about IAU you can check their official website..


Well it's quite simple. The answer is "MAGNETIC FIELD" of the earth..


Unlike earth, the sun has an extremely complicated magnetic field.A large part of this magnetic field runs beneath the surface of the sun in the form of so - called "magnetic tubes".Sometimes these tubes can break through the sun's surface, and where they do so,strong magnetic fields prevent hot matters from rising out of the sun's interior,cooling the affected areas of the surface to a temperature of 4000^o c. Because of their lower temperature, these regions aren't bright as the rest of the sun - which is about 1500^o c hotter - & thus they appear as dark spots on the sun's surface.Sunspots are between 2500 km and 50000 km wide, which means they can be several times larger than earth.The life span of individual sunspots varies from days to months.


 Sunspots numbers rise and fall in a cycle of approximately 11 years. The last sunspot maximum was in 2000,so the next one is expected in 2011.The sunspot cycle is controlled by the sun's magnetic field,which changes direction every 11 years.


Our sun is definitely not exceptional,and other stars also have dark spots in number's  that fluctuate in accordance with a regular cycle.The magnetic processes at work appear to be very similar. These 'starspots' can be even larger than the spots on our sun.


The "CORONA" is the sun's thin external atmosphere. Sound waves & magnetic fields heat the gas in the corona to a temperature of over 1 million degrees celsius. This high temperature causes the corona to emit x-rays.However, it also emits a lot of light, which is why the corona can be seen with the naked eye when the sun's bright disc is covered,as is the case during a total eclipse of the sun. In order to observe the corona, space scientists use a special telescope,like the one aboard the solar and heliospheric observatory(SOHO) spacecraft, which has been fitted  with a device to cover the disc of the sun. The corona stretches several million kilometres in to space two or three times the diametre of the sun


Well it's a fact that scientists are hunting for neutrino's. but why? this has been our question right? so here it is......

        The process of "nuclear fusion" within the sun generates a huge no of neutriono's as well as EMR( Electro Magnetic Radiations). Neutrinos are mysterious elementary particles. They have miniscule mass and are able to pass through matter almost undisturbed, which is why, in contrast to radiation, the neutrino's that originate in the core of the sun arrive at the earth in only 8 minutes. About 70 billion neutrinos strike each square centimetre of our planet every second. Physicists are developing gigantic detectors in their efforts to catch at least a few of these elusive particles to help them understand a few more of the mysteries of the sun's interior.


                     One such detector is The "SUPER KAMIOKANDE" detector which is 59m high and fitted with more than 11000 photomultiplier tubes which are used to detect neutrinos.


you see the tiny tiny things here in the picture these are the "photomultiplier tubes"


   So far scientists have found liquid water only on earth.That is the reason maybe life was first originated on earth. Some suspect that there may be frozen water in the perpetually shaded regions around Mercury's poles. Frozen water is also present near the poles on mars, and it is highly probable that there is an ocean on jupiter's moon "EUROPA"

              Magnetic field measurements indicate that an ocean about 100 km deep is concealed under a 1 km thick layer of ice on jupiter's moon- europa.It may be that the giant planet's gravity heats the inside of the moon by 'squeezing' it thoroughly, maintaining any water in a liquid form.The american space agency NASA is currently working on plans to send a space probe to this moon in an attempt to find out what exactly is happening there.


"VULCANISM" - Well vulcanism(verb) means volcanic activity or volcanic eruption....

               Astronomers have discovered old volcanoes on venus, as well as on mars. So far, no active vulcanism has been detected on any other planet, although it has been detected in jupiter's moon "IO". However, atmospheric gases on venus indicate that there may be active volcanoes on that planet as well....

there you see the small one is the "IO"



In the inner solar system, the young sun's radiation blew away any leftover gas at an early stage, but it was preserved for a longer period in the outer areas.This is why those planets that formed in the outer regions of the solar system had more time to attract the gas present in their surroundings, and so grew for much longer.


WORM HOLES:- A Wormhole is just like a space portal which acts as a shortcut for a journey to other galaxies.... it's just an assumption well there is no proof at present for the existence of "wormhole's"... 

Because we are restricted to velocities below the speed of light, the kind of space travel to distant stars and galaxies we see depicted in science fiction films is impossible.The realisation that this is the case, & that humankind may never visit even a fraction of the "vast" universe, is a situation that even some physicists find unsatisfactory.This has lead to a search for loopholes in the laws of physics that may make intergalactic space travel possible. One such loophole involves the possibility of so called "wormholes" in space. These strange entities are a consequence of the theory of relativity, and the suggestion is that distant regions of the universe may be connected by a kind of space-time tunnel.However,theory predicts that wormholes will be unstable and so unsuitable for use as shortcuts by future astronauts. As soon as they have formed- if indeed they do form - they would collapse again. One suggestion is that wormholes could be stabilized by matter with "NEGATIVE ENERGY & NEGATIVE GRAVITY". Unfortunately - like wormholes themselves - this kind of matter exists only in theory so far. 


WELl you know guys.... this question got in to my mind when i was in 7th class...... :P  it seems strange but when i asked someone i know who are elder to me they haven't answered to me .....

it's quite simple.... of course i would go somewhat logic wise.. 


                    The earth rotates very rapidly, it's speed at the equator being almost 1700 km/h. To keep all of the inhabitants of the earth firmly on the ground and rotating along with the planet,requires the gravitational pull of the earth's immense mass. It is "GRAVITY" that keeps our feet on the ground.In fact, there is a reduction in weight due to rotational speed that means we weigh around 0.5% more at North & South poles than we do at the Equator.If there was a planet that actually rotated so fast that it was impossible for it's inhabitants to be held down by gravity if they stood at it's equator, the planet itself would fly apart.


In 1928 an Indian graduate student named subrahmanyan Chandrasekhar set sail for england to study at cambridge with the british astronomer Sir Arthur Eddington.Eddington was an expert on general relativity.

           During his voyage to india,Chandrasekhar worked on how big a star could be and still separate itself under it's own gravity after it had used up all it's fuel.The idea was this: when the star becomes small, the matter particles get very near to each other.But the pauli exclusion principle says that two matter particles can't have both the same position and the same velocity.The matter particles must therefore have very different velocities.

This makes them move away from each other,and so tends to make the star expand. A star can therefore maintain itself at a constant radius by a balance between the attraction of gravity and the repulsion that arises from the exclusion principle, just as earlier in it's life the gravity was balanced by the heat.

           Chandrasekhar realized, however, that there is a limit to the repulsion that the exclusion principle can provide.The theory of relativity limits the max difference in the velocities of the matter particles in the star to the speed of light. That meant that when the star got sufficiently dense, the repulsion caused by the exclusion principle would be less than the attraction of gravity.Chandrasekhar calculated that a cold star of more than one and a half times the mass of the sun wouldn't be able to support itself against it's own gravity. This mass is now known as the "CHANDRASEKHAR LIMIT".  


Well before going for the question i'll quickly post some properties abt light. well "light" can travel with a speed of 3 lakh m/s where as in miles it is 6.702 * 10^8 miles/hour.

            Scientists stop light completely for a record-breaking MINUTE by trapping it inside a crystal! 


Scientists in Germany have succeeded in stopping light - the fastest thing in the universe - for a whole minute, smashing earlier records.  

Researchers at Darmstadt Technical University achieved the remarkable feat by trapping it in a crystal.  

In a paper published this month in the journal Physical Review Letters, the scientists explained how they stopped the light using a technique called electromagnetically induced transparency.

At full pelt, light would normally travel about 11 million miles in one minute – equivalent to more than 20 round trips to the moon. 

'One minute is extremely, extremely long,' Thomas Krauss, Professor of optoelectronics at the University of St Andrews, UK, commented to the New Scientist. 'This is indeed a major milestone.' 

The physicists, Professor Thomas Halfmann, Christian Hubrich and PhD student Georg Heinze, also used the same technique to store and then retrieve an image consisting of three stripes. 'We showed you can imprint complex information on your light beam,' said researcher Georg Heinze.  

The results may further light-bas


well, a scientist inspired by the "EIFFEL TOWER" construction had a thought in his mind.He decided to construct a tower of height 348000 km near our earth's equator.At the top of this tower if a person reaches he will be able to easily float in the space,and the tower's speed would match the earth's orbit speed.Neverthless that ain't gonna happen.But the idea is nice isn't it? An american scientist realized that the tower itself wasn't necessary.All that was needed was a rope that could tie the lift from a satellite to the earth. But the only problem is the material with which that rope would me made of. Even steal of width 90 km can't hold that much weight.Well still an american space organization has planned to launch a lift into the space by 2025.They decided to make the rope from "carbon micro nanotubes".