what is an anti-matter ?

Answer 1

(m)

Matter which consists of antiparticles, elementary particles of ordinary matter, such as protons and electrons, but have an opposite electrical charge. For example, an antiproton has a negative charge while a proton has a positive charge. When a particle of matter and a particle of antimatter come into contact with each other they are destroyed, releasing energy.

Answer 2

In particle physics, antimatter extends the concept of the antiparticle to matter, wherein if a particle and its antiparticle come into contact with each other, the two annihilate —that is, they may both be converted into other particles with equal energy in accordance with Einstein's equation E = mc2. This gives rise to high-energy photons (gamma rays) or other particle–antiparticle pairs. The resulting particles are endowed with an amount of kinetic energy equal to the difference between the rest mass of the products of the annihilation and the rest mass of the original particle-antiparticle pair, which is often quite large.

Antimatter is not found naturally on Earth, except very briefly and in vanishingly small quantities (as the result of radioactive decay or cosmic rays). This is because antimatter which comes to exist on Earth outside the confines of a suitably equipped physics laboratory would inevitably come into contact with the ordinary matter that Earth is made of, and be annihilated. Antiparticles and some stable antimatter (such as antihydrogen) can be made in minuscule amounts, but not in enough quantity to do more than test a few of its theoretical properties.

There is considerable speculation both in science and science fiction as to why the observable universe is apparently almost entirely matter, whether other places are almost entirely antimatter instead, and what might be possible if antimatter could be harnessed, but at this time the apparent asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics. Possible processes by which it came about are explored in more detail under baryogenesis.

Answer 3

i hope that you are familar with elementary ideas of special theory of relativity(str) and quantum physics(qp).
if not you can refer to any standard book on the subject (see references). in str the total energy contend of any object is given by a formula:

E^2 = (p*c)^2 + (m*c^2)^2 -------- <1>

where m is mass of the object and its momentum is given by p.
c is the speed of light.
eq. 1 only tells about the square of E and not E, it can be positive or negative. one usually assumes positive E in classical physics.
and refered to as matter.
when one goes to qp, and looks to same equation but from the view point of qp it is called the dirac eqn. the two family of solutions of this eqn have +ve E and -ve E. it is so found that solns with -ve E actually have +ve E but propagate backward in time !
akward to digest !?! i.e they first die and then are born.
well idea is to get a minus sign for E, from a minus sign of t, because in qp :

operator E -> i*h*(d/dt) ----------<2>

(i am not able to write properly but hope you are getting it .. )
so if t changes to -t then you can get a minus sign for E, and hence now solns have +ve E but are moving backward in time.

note that this pure str and qp effect. now you call this soln as anti matter becuase it has a different sign. but there is nothing sacred about the them, whole physics is same for them albeit with some redefinations. infact given an isolated object of antimatter it is impossible to make out . but the when matter and antimatter collide they annhilate each other producing light, popularly shows by drawing a feynman diagrams.

to give you can analogy it is something like a ripple in the rubber band, you can twist a rubber band clockwise or anticlockwise, one c-wise riple when collides with antic-wise, there will be no ripple at all !

i hope it is not too boring.

Answer 4

Atomically, it's made up of atoms that have negatively charged nuclei and positive electrons.

Answer 5

its mean oppose the matter

Answer 6

it`s more a ? of what is it not.