A brief History of Atom

chandraman_karki@yahoo.com 

Chandra Man Karki

A unit of matter, the smallest unit of an element, consisting of a dense, central, positively charged nucleus surrounded by a system of electrons, equal in number to the number of nuclear protons, centimeter and characteristically remaining undivided in chemical reactions except for limited removal, transfer, or exchange of certain electrons.

John Dalton

An English scientist called John Dalton put forward his ideas about atoms. From his experiments and observations, he suggested that atoms were like tiny, hard balls. An element is a substance made from only one type of atom. An element cannot be broken down into any simpler substances. Element had its own atoms that differed from others in mass. Dalton believed that atoms were the fundamental building blocks of nature and could not be split. In chemical reactions, the atoms would rearrange themselves and combine with other atoms in new ways.
In many ways, Dalton's ideas are still useful today.

J.J. Thomson

At the end of the nineteenth century, a scientist called J.J. Thomson discovered the electron. This is a tiny negatively charged particle that is much, much smaller than any atom.
Thomson proposed a different model for the atom. He said that the tiny negatively charged electrons must be embedded in a cloud of positive charge (after all, atoms themselves carry no overall charge, so the charges must balance out). Thomson imagined the electrons as the bits of plum in a plum pudding.

WIDE ANGLE: Is time travel possible?

 Time as a Flowing River

"Time flows like a river and it seems as if each of us is carried relentlessly along by time's current. But time is like a river in another way. It flows at different speeds in different places and that is the key to traveling into the future," Hawking writes.

                  

Albert Einstein first proposed this idea 100 years ago that there should be places where time slows down, and others where time speeds up, notes Hawking. "He was absolutely right."

The proof, says Hawking, lies in the Global Positioning System satellite network, which in addition to helping us navigate on Earth, reveals that time runs faster in space.

"Inside each spacecraft is a very precise clock. But despite being so accurate, they all gain around a third of a billionth of a second every day. The system has to correct for the drift, otherwise that tiny difference would upset the whole system, causing every GPS device on Earth to go out by about six miles a day," Hawking writes. The clocks aren't faulty -- it's the pull of Earth that's to blame.

Do the virtual particles exist?

     Virtual particle are indeed real. They have observable effect that physicists have devised ways of measuring it. Quantum theory predicts that every particle spends some time as a combination of other particle in all possible ways. Quantum Mechanics allows and indeed requires temporary violations of conservation of energy. So, one particle can become a pair of heavier "virtual" particle which quickly rejoin into original particle almost as if they had never existed.

While the virtual particle are briefly part of our world, they can interact with other, less exotic particles and researchers can study these interactions to test prediction about virtual particle. In a hydrogen atom, Photon (elementary particle of electromagnetic radiation) binds together a negatively charged electron and a positively charged proton. Every photon will spend some time as virtual electron plus its antiparticle, the virtual position as described above. The hydrogen atom can be in more than one state, in one of those states, the atom

CERN (European Organization for Nuclear Research) moves closer to antihydrogen spectroscopy

Physicists at CERN have taken a big step towards making the first spectroscopic measurements on a beam of antihydrogen atoms. The antihydrogen atoms, which consist of an antielectron orbiting an antiproton, were made by members of the lab's ASACUSA group. The beams could be used to carry out the first detailed studies of the energy levels in antihydrogen.
Measuring in detail the energy levels in antihydrogen is important because the Standard Model of particle physics says they should be identical to those of hydrogen. Any slight differences in the "fine structure" of the levels compared to ordinary hydrogen could shed light on why there is so much more matter than antimatter in the universe.
The breakthrough comes just weeks after researchers in the ALPHA collaboration at CERN succeeded in trapping 38 antihydrogen atoms for about 170 ms.This was the first time that antimatter atoms had been stored for long enough to measure their properties in detail and, taken together, the two results represent major advances in studies of antimatter.
by:
Sailes Bataju
BSc. 1st year

Ahead of Einstein’s Time

 What would Albert Einstein think if he were alive today?

         As a theorist who was interested in experiments, in his early career at least, he would be pleased to know that a small band of 21^st century physicists are still trying to find flaws in the special theory of relativity, while others are busy checking out the predictions of the general theory, And having spent the final years of his life trying to unify general relativity with electromagnetism, without success, he could be forgiven for thinking that criticisms of his relative non-productivity in those years were somewhat unfair. No-one else has succeeded where he failed.

REVERSE OF THE LOUDSPEAKER

Loud speaker is a device which converts the electrical energy into the sound energy. But how the loud speaker works? The shape of loudspeaker is like a cone made of plastic. In the middle, the round shaped permanent magnet is fixed which produces fixed electric field. In the middle of magnet there is space where a piece of soft iron core is kept. This iron core is wounded by the wires and it can move.

When the ac current is supplied, the pole of magnet also changes and produces attraction and repulsion force between the magnet and iron. Due to this movement of soft iron core, vibration is produced which results mechanical wave (sound).  In this way the loudspeaker sends out sound in all directions.

Now what happens if the loudspeaker is made to work in the reverse way?

How Heavy Is The Earth ?

Now despite science coming forward in leaps and bounds the simple question of how much the Earth weighs isn’t as straightforward as you might think. Certainly placing the earth onto a massive set of weighing scales isn’t an option. So how do we measure the total weight of the Earth?
Well scientists initially went about this task by trying to estimate the weight of a very large mountain and then simply scaling that figure up. However this method led to some peculiar results and since then the mathematics and calculations involved have changed taking into consideration further factors such as the volume and overall density of the planet.
If you combine the above with weighted samples of various parts of the planet scientists have come up with a more accurate number which they believe to be around 6 quadrillion kilograms.

Newton's Three Laws

In our daily life we see the body being at rest, at constant motion or in acceleration. Now, Newton explains about these state of body in his three law of motion.

Newton, in his first law of motion, states, "Every object continues in its state of rest or of uniform motion along a straight line unless an external force acts on it". It explains about the inertia possesses by every object. The body at rest will continue the state of rest if an external force is not applied and this is inertia of rest. Again the body at motion will continue in the state of motion with constant speed along the direction in straight line if an external force is not applied and this is called inertia of motion.

The fundamental force in nature

In the universe, there are different types of force but I am going to explain about these forces which created in the origin of the universe. These forces are strong force, weak force, electromagnetic force and gravitational force. In the time of big bang, these four fundamental forces were believed as a single force, called unified force. Now most physicists hope to find a unified theory, but they don’t success to solve this problem. After big bang, the universe cooled, and then the forces separated as the original symmetries were broken. Now I shall describe four fundamental forces.

Gravity

1. When we throw any object into sky, then it returns back to earth’s surface. Rivers and streams flow downward from hills and mountains. Rainfall occurs in the downward direction. Earth revolves around sun and moon revolves around earth. Eight planets of solar system moves around the sun. Atmosphere surrounds the earth. There is something that return the thrown stone to earth surface, makes river flow downward, rainfall occurs downward furthermore, there is something that draw the earth toward the sun and the moon towards the earth and eventually the eight planets of solar system toward the sun. That something is pulling force. This force is called gravity force.