Importance Of Proton Decay For GUT

Proton and neutrons behave in totally different ways though they are almost have same mass ( Neutron slightly heavier than proton). In nucleus Neutron decays into proton ,electron and electron antineutrino and is called beta negative decay.This involves a weak nuclear force and hence uses the W- boson for the decay process.The other type beta positive decay involves a proton converting into neutron ,a positron and an electron neutrino. Here also the decay is carried out by the weak nuclear force but uses W+ boson instead of W- . 

These process happen inside a nucleus . Outside the nucleus a single neutron decay within 15 minutes but proton doesn't decay and there is no experimental proof so far and it estimated that the life time of proton is extremely high 1034  years. Since a proton converts into a neutron which is slightly heavier than proton some energy has to be converted into mass which is not possible outside the nucleus.

Super-Kamiokande experiment to find a proton decay is still elusive and this experiment is very crucial for GUT (Grand unification theory). In fact Japan is building even a bigger hyper-Kamiokande detector for finding a proton decay.   

Similarities Between An Atom And A Star

There is lot of similarity between an atom and a star. In an atom the coulomb repulsive forces between the protons in the nucleus are balanced by the strong nuclear forces. The strong nuclear force is created between nucleons by the exchange of particles called mesons. As long as meson exchange can happen the strong force is able to hold the participating nucleons .The nucleons must be extremely close together at a distance of 1 Fermi( 1.0 × 10⁻¹⁵ meters) in order for this exchange to happen.,

 

Where as in a star the gravitational contraction is balanced by the nuclear fusion where hydrogen fuses to produce helium and releases enormous energy. This energy stops the gravitational contraction.

When a new star is born gravitational contraction happens which creates very high temperatures at the core when the temperature raises to 100 million degrees the fusion reaction takes place and the energy released balances the gravity push and the gravitational contraction stops.

Therefore its quite reasonable to expect a single theory or equations describing the gravity and quantum theory or quantum gravity. 

Many unanswered questions in cosmology

The Big Bang a unproved conjecture happened 13.8 Billions years ago, assuming that it really happened, Big Bang started from singularity which arises from using Einstein’s equations for gravity. Its very very long time ago, many things or process might have happened and they don't  exits now .The only resources we have to find what happened 13.8 Billions back are the telescope however sensitive it may be and the light (electromagnetic waves) . These tools may not be enough to predict what happened since Big Bang. To correctly predict all the events that have happened right from the Big Bang we need to have all or most of the recordings of all the events which is almost impossible.

Whether why matter dominated the antimatter or who turned on the Higgs field to give the mass to the particles are very difficult or almost impossible to predict. 

Many more questions remained unanswered ,what was there before Big Bang, what caused Big Bang and do we have single universe or multi-universe. The dark matter and dark energy still a mystery . Finally how universe is going to end in a big crunch or ripped apart because of endless expansion. 

We are still in search of a single theory often referred to "theory of everything" which can combine both Einstein general theory of relativity which applies to large structures of universe and the quantum theory which applies to subatomic particles. A single theory which unifies all the fundamental forces of universe. I mean quantum gravity .

The most important fact is that many process are difficult to replicate in laboratory. But scientific endeavor continues.

How Big Is The Sun Compared To Earth

The radius of Earth at the equator is 6,378 kilometers, however Earth is not quite a sphere.The planet's rotation causes it to bulge at the equator. Earth's polar radius is 6,356 km  a difference of 22 km.

The sun is nearly a perfect sphere. Its equatorial diameter and its polar diameter differ by only 10 km. The mean radius of the sun is 696,000 kilometers.

Volume of a sphere is V = 4/3 πr³

The ratio of volume of sun to Earth =  (4/3 πR³ ) / (4/3 πr³)

                                                             = (R/r)³

Where R is the radius of Sun and r radius of Earth

The ratio of Sun to Earth radius = R/r = 696,000/6,378  = 109.125

The ratio of volume of sun to Earth = (R/r)³ = (109.125)³ = 1299489 or approximately 1.3 million earths can fit inside Sun. 

The mass of the sun is  1.9891 x 10³⁰ kg about 333,000 times the mass of the Earth. The Sun contains 99.8 percent of the mass of the entire solar system.

   

Einstein Deserves Nobel Prize For Relativity

Einstein was disappointed that he did not receive Nobel prize for the theory of relativity instead he was awarded Nobel prize for photoelectric effect in 1921 ,actually he received it in 1922 . He proposed both photoelectric and relativity theory in 1905 .

Einstein general theory of relativity describes how gravity can distort the path of light,altering its trajectory called gravitational lensing. He was denied Nobel prize because committee decided against his work on the grounds that relativity was unproven. 

Cambridge astrophysicist Arthur Eddington measured the deflection of stars' positions near the Sun, the size of the deflection was exactly as Einstein had predicted from relativity in 1915 using total eclipse. But still he was denied because of the war and politics or may be antisemitism.

Albert Einstein also predicted the existence of gravitational waves in 1916 in his general theory of relativity. According to his theory  massive accelerating objects such as neutron stars or black holes orbiting each other would disrupt space-time in such a way that waves of distorted space would radiate from the source and the ripples would travel at the speed of light through the Universe.

After 100 years of Einstein General theory of Relativity prediction of gravitational waves gets a Nobel prize for the discovery of gravitational waves using the LIGO detector. Nobel Prize was awarded to Rainer Weiss of the Massachusetts Institute of Technology and Barry Barish and Kip Thorne of the California Institute of Technology, all members of the Ligo team. 

One of the most famous equations E=mc²  which revolutionized science comes from special theory of relativity, could have got a Nobel prize on its own. The significance of this equation is that mass and energy are different forms of same thing and transmutable.

Today's solar energy revolution is because of Einstein theory of photoelectric effect. Einstein should have won more than one Nobel Prize.

The Cosmological Constant

The cosmological constant was originally introduced by Einstein in 1917 as a repulsive force required to keep the Universe in static equilibrium which follows steady-state-theory. In trying to solve the differential equations that describe space-time, his field equations predicted that the universe should be either contracting or expanding. In the year 1922, Russian physicist Friedmann derived solutions to Einstein's equations that corresponded to an expanding universe. Einstein needed to add a constant term to avoid having the universe collapse upon itself. This term balances the attractive force of gravity contributed by all of the matter in the universe.  

Hubble's study of nearby galaxies showed that the universe was in fact expanding and that lead to the Big Bang theory, the concept introduced in 1927 by Georges LeMaitre.Einstein regretted the introduction cosmological constant to keep the universe static and termed it as greatest mistake.

After almost 100 years we realized that the Universe does in fact have a non-zero cosmological constant: that’s what we call dark energy, and use to explain the accelerated expansion of the Universe. Physically, this term represents the vacuum energy, the possibility that empty space possesses density and pressure thus preventing the universe from collapsing.

If indeed the cosmological constant represents the dark energy or vacuum energy then Einstein by mistake proposed the dark energy concept.