CHAPTER 5: RELATION BETWEEN GENERAL RELATIVISTIC GRAVITY AND QUANTUM GRAVITY

    As mentioned in the last chapter, we learned a brief description about gravity in quantum level. In this chapter, we are going to see about the description of gravity given by Einstein and its relation with the quantum gravity.

   Einstein mentioned gravity in such a way in his research paper in such a way that its effect on quantum level will be very much small(negligible) which follows the description of gravity in quantum level. The general relativistic gravity can be exemplified as follows: If we keep a football in the center of a paper and a tennis ball on the side the paper, it will be attracted strongly by the basketball, but on the other side if we keep the feather of a pigeon on the other side it will not be attracted much strongly towards the ball. The same effect is applied in reality. The quantum particles do not experience much gravity because of their very small size. But, is gravity depends only on mass and size?  

  The effect of gravity not only depends on the size and mass of particles, but also on the shape and curvature of the particles. To understand this, let's see an example: Take two papers which are not in contact with each other. In first paper keep the football and see the curvature of the paper on beneath the football. In other paper, keep one golf ball and note down its curvature on the paper beneath the ball. What will be noticed by these experiment? The curvature of the paper as seen in the case of football will be u shaped. And same in the second case. But the major difference in the two cases is the depth of u shape. In second case the depth of u shape is higher than that in the first case, i.e. in the first case the it will not be a perfect u shape, but in the second case the shape of the golf ball will be a perfect u. By these experiment it will be concluded that due to the perfect shape of u the gravitational effect shown by golf ball will be slightly greater than football.

   The football mentioned above is like a black hole, Its not like that the gravity is weaker, the gravitational effect of a black hole is very much stronger, but not much that the light cannot escape it. Because if this happens, then the rest part will be science fiction as mentioned in the movie interstellar. The person who falls inside the black hole will experience things faster than any other object in the universe, because indirectly the person is travelling at a speed greater than light which violates all practical rules and laws of physics. But the universe is very much big beyond our imagination. Is it possible that the universe works exactly like our physics?

   Here comes quantum mechanics which violates all the laws of physics. Any object in the universe can't travel at a speed of light. But this is not the case in quantum level. In quantum level there is an effect known as butterfly effect. According to this effect if we doing any basic action on the earth in one place, its effect will be sent to the universe greater than speed of light and will be reflected back towards us. This is what we call 'karma'. Are there any other any particles which carry photons with such a high speed? The answer is both yes and no. In practical world, the photon particles are massless and due to this the photon particles are not effected by any force in the universe because every object has mass. But in quantum world every object is connected with each other. In quantum level, photon particles are carried by some other particles or wave which give the photons the speed of light. Its like the air and the leaf on the ground. The air is the carrying wave or particle and the leaf is like a photon. The leaf travels as the air travels. And also air is everywhere in the earth which carry many objects like leaf. It is obvious that air travels at a speed greater than leaf. Same is the case with the carrier particles or wave of photons.

  And also because of this, we can see the two nature of electrons in double slit experiment. We can say that the butterfly effect is produced by our eyes(like the air to leaf) to the electrons due to which it changes its form when we detect it with eyes and when we not. And so, the black hole can't violate the laws of physics as physics laws can only be violated in quantum level and not in the physical world. Because of the negligible effect of quantum gravity, the strings of quantum gravity can travel to other smaller dimensions and may be the quantum gravity is the unified force (origin force), and therefore we can't detect its effect on minute particles but according to relativity if our size reduces like photons then we can detect the effect of quantum gravity and therefore relatively  quantum gravity may be the butterfly effect or 'karma'.

CHAPTER 4: UNDERSTANDING GRAVITY

What is gravity?

Do we really know what is gravity and how it practically works? 

Do we understand the origin of gravity?

What are the force carrier particles of gravity?

How gravity really works in black hole?

Is Einstein's description of theory in general theory of relativity true?

      

     These are some questions about gravity which we are going to discuss in this chapter.

    

    To understand gravity we must understand the origin of all other three forces (i.e strong nuclear force, weak nuclear force, electromagnetic force) and how matters are produced in quantum level and how these forces work in quantum level.

      Every particles in this universe are divided into two categories: 1.Fermions  2.Bosons

     Fermions are responsible for the formation of every matter in this universe. Fermions also contain two types of particles 1.Quarks 2.Leptons                                                              Quarks are of six types 1.up (u)  2.down (d)  3.charm(c)  4.strange(s)  5.top(t)  6.bottom(b)    Quarks are very unstable particles due to which they come together to form new particles which are known as hadrons. Hadrons are also divided into two types 1.Baryons  2.Mesons   Baryons are formed by the combination of three quarks. Protons and neutrons are  formed by the combination of two quarks(i.e. up and down). Protons are formed by the combination of two up and one down quarks whereas neutrons are formed by the combination of two down and one up quarks. Mesons are formed by the combination of one Quark and one Anti-Quark (kaon, pion, etc.). The combination of other four types of quarks gives rise to other different types of particles. Leptons are not formed by the quarks because they are stable particles. Leptons are also of six types: 1.electron neutrino(ve)  2.electron(e-)  3.muon neutrino(vu)  4.muon(u)  5.tau neutrino(vt)  6.tau(T). In the above classification of both quarks and Leptons numbers: 1&2-Family I,  3&4-Family II,  5&6-Family III.  Like electrons, leptons also have anti particles. Here, fermions do not contribute to the working, construction and formation of forces.

    Boson particles are responsible for the formation of some forces. Bosons are of four types 1.Photons  2.W/Z Boson  3.Gluons  4.Gravitons*                                                                       The formation of electromagnetic force is due to photon particles. Electromagnetic force can't be generated without photons. The W/Z Boson particles are responsible for the formation of Weak nuclear force. Due to weak nuclear force, beta decay occurs and anti-neutrino is formed. This force converts protons into neutrons by releasing some amount of radiation. Gluon particles are responsible for the formation of strong nuclear force. This type of force is very much strong approximately 1000 times stronger than 2nd strongest force(i.e. weak nuclear force). This force is so much strong that this force can hold protons which are positively charged and neutrons which are neutral together in one nucleus. 

    Besides all this, the particle which is responsible for gravitational force is not discovered. We gave one hypothetical name for this particle (i.e. gravitons). In so called black hole formation we assumed that the range of gravitational force is infinite which is not possible because for this to happen the mass of that object should be zero which is again one impossible loop. This force is the weakest of all forces. This force is 1 trillion times weaker than weak nuclear force. The reason for so much amount of weakness can be explained with the help of string theory. According to string theory, quarks and electrons are attached to only one dimension because which the quarks and electrons strings cannot move in other dimensions and hence we can detect them. Gravitons are closed strings and they are not attached to any membrane due to which they keep on travelling from one dimension to another dimension. Due to this we can't easily detect them. But in Large Hadron Collider if we create enormous amount of energy at that point of second when the graviton strings are in our dimension we could know some practical properties of gravitational force.

     By studying force from Big-Bang till now we came to know the combination different forces. When the Big-Bang occured all the forces were unified. Because the origin of gravitational force is not discovered we assume that after big-bang gravitational force was divided and after that strong nuclear force got divided. After that electroweak force was the 3rd existing force & and after certain time we discovered that the electroweak force gave birth to electromagnetic force and weak nuclear force. 

    How Einstein's gravitational force description can be related to the above formation of force and black hole will be explained in the next chapter...