Surprising Things About the Universe

• Since gravity weakens with distance, the earth pulls on your head with less force than it pulls on your feet, which are a meter or two closer to the earth's center. The difference is so tiny we cannot feel it, but an astronaut near the surface of a black hole would be literally torn apart.
• The inherent goal of unification is to show that all of these forces are, in fact, manifestations of a single force. We can't perceive this unity at the low energies of our everyday lives, or even in our most powerful accelerators at CERN. But close to the Big Bang temperatures, at inconceivably high energies… If the forces unify, the proton can be unstable, and eventually decay …

Proton → positron + neutral pion

Neutral pion → 2 gamma ray photons

• Sun emits 2×10 to the power of 38 neutrinos per second but only 30 neutrinos are interacting in a person per year.
• The entire electromagnetic spectrum —from radio waves to gamma rays, most of the light in the universe — resembles nothing but transverse waves of energy E = hc/λ, which in turn are vibrating Maxwell force fields differing only in their wavelength λ = h /p.
• The different frequencies of light appear as different colors.
• Gravity waves are vibrations in the 4 dimensional fabric of space-time. Gravitons are their quanta.
• DNA carries information but cannot put that information to use, or even copy itself without the help of RNA and protein.
• There is no escape from a black hole in classical theory, but quantum theory enables energy and information to escape.
• If not for a force called gravity, we would all go zinging off into outer space.
• The more massive a star, the more luminous it will be. This rule is called the mass-luminosity law.
• The unification of so called weak nuclear forces with the Maxwell equations is what known as the Electro-weak theory. And the electro-weak theory and QCD together constitutes the so called Standard Model of particle physics, which describes everything except gravity.
• What goes up need not come down — if it is shot upward faster than the escape velocity.
• When 2 similar waves are added, the resultant wave is bigger (constructive interference) and when 2 dissimilar waves are added, they cancel each other out (destructive interference).
• The objects of different masses are accelerated towards the earth at the same rate, but with different forces.
• Observations of galaxies indicate that the universe is expanding: the distance D between almost any pair of galaxies is increasing at a rate V = HD.
• When we place two long parallel uncharged plates close to each other, virtual particles outside the plates exerts more pressure than the virtual particles inside the plates, and hence the plates are attracted to each other, which we call the "Casimir effect."
• Quantum mechanics says that the position of a particle is uncertain, and therefore that there is some possibility that a particle will be within an energy barrier rather than outside of it. The process of moving from outside to inside without traversing the distance between is known as quantum tunneling, and it is very important for the fusion reactions in stars like the Sun.
• Newton rings is a phenomenon in which an interference pattern is created by the reflection of light between two surfaces — a spherical surface and an adjacent flat surface. It is named after Isaac Newton, who first studied them in 1717.
• Electric and magnetic forces are far stronger than gravity, but remain unnoticeable because every macroscopic body contain almost equal numbers of positive and negative electrical charges (i.e., the electric and magnetic forces nearly cancel each other out).
• By analyzing the stellar spectrum, one can determine both the temperature of a star and the composition of its atmosphere.
• If the leptons would have felt the strong force, then they would have combined to form different particles. The entire picture of Particle Physics would have been quite different.
• Long-duration gamma ray bursts are associated with the deaths of massive stars in a specific kind of explosion called a supernova.
• As mercury repeatedly orbits the sun, the long axis of its elliptical path slowly rotates, coming full circle roughly every 360,000 years.
• Because the square of the time it takes for the planet to complete one revolution around the sun is proportional to the cube of its average distance from the sun, the mercury move rapidly in its orbit and Venus, Earth and Mars move progressively less rapidly about the sun and the outer planets such as Jupiter, Saturn, Uranus, Neptune and Pluto move stately and slow.

Energy budget of the universe;

13.7 Billion Years ago (when the Universe was 380,000 years old)

• Dark Matter: 63%
• Neutrinos: 10%
• Photons: 15%
• Ordinary Matter: 12%

Today

• Dark Matter: 23 %
• Dark Energy: 73%
• Ordinary Matter: 4%
• Out of 4% we only make up 0.03% of the ordinary matter.

Quantum mechanics (the theory of subatomic physics and one of the most successful theories of all time) is based on three principles:

1. Energy is found in discrete packets called quanta.
2. Matter is based on point particles but the probability of finding them is given by a wave, which obeys the Schr?dinger wave equation.
3. A measurement is necessary to collapse the wave and determine the final state of an object.

• The discovery and confirmation of the cosmic microwave background radiation, or CMBR, in 1965 secured the Big Bang as the best theory of the origin and evolution of the universe.
• If the two quarks would have occupied precisely the same point with the same properties, they would not have stayed in the same position for long. And quarks would have not formed separate, well-defined protons and neutrons. And nor would these, together with electrons have formed separate, well-defined atoms. And the world would have collapsed before it ever reached its present size.
• Neither of these extremes would have allowed for the existence of stars and life: A slightly stronger weak force, all the neutrons in the early universe would have decayed, leaving about 100 percent hydrogen, with no deuterium for later use in the synthesizing elements in stars. A slightly weaker weak force, few neutrons would have decayed, leaving about 100 percent helium, with no hydrogen to fuel the fusion processes in stars.
• Matter bends the fabric of space and time. The distortion of the space-time affects the path of light.

"Matter tells space how to curve, and curved space tells matter how to move."

Matter → curvature of space-time

• The ultimate fate of the universe is determined by whether the density parameter is less than, equal to or greater than 1.
• When two black holes collide, they merge, and the area of the final black hole is greater than the sum of the areas of the original holes.
• Because E = mc squared the energy which an atom has due to its motion add to its rest mass and as an atom approaches the speed of light, its mass raises ever more quickly, it acquire infinite mass and since an infinite mass cannot be accelerated any faster by any force, the issue of infinite mass remain an intractable problem.For this reason all the atoms are forever confined by relativity to move at speeds slower than the speed of light. Only radiation that has no intrinsic mass move at the speed of light.
• The two neutron stars that are orbiting each other continually emit gravitational waves. These waves carries energy at the speed of light and are now considered as fossils from the very instant of creation . . . . since no other signal have survived from that era.
• The quarks are much smaller than the wavelength of visible light and so they do not possess any color in the normal sense.
• Linking the two chains in the DNA, are pairs of nucleic acids (purines + pyrimidines). There are four types of nucleic acid, adenine "A", cytosine "C", guanine "G", and thiamine "T." An adenine (purine) on one chain always matches with a thiamine (pyrimidine) on the other chain, and a guanine (purine) with a cytosine (pyrimidine). Thus DNA exhibits all the properties of genetic material, such as replication, mutation and recombination. Hence, it is the molecule of life.
• The natural selection is a choice of stable forms and a rejection of unstable ones. And the variation within a species occurs randomly, and that the survival or extinction of each organism depends upon its ability to adapt to the environment.
• Surface gravity is the same at all points on the event horizon of a black hole, just as the temperature is the same everywhere in a body at thermal equilibrium.
• Every living organism is endowed with two elements "genes" ? a set of instructions that tell them how to sustain and multiply themselves and "metabolism" ? a mechanism to carry out the instructions.
• Every living cell of cyanobacteria, and eventually higher plants (including flowering angiosperms, orchids, conifers and other cone bearing gymnosperms, ferns, club mosses, hornworts, mosses and the multicellular eukaryotes of the kingdom Plantae) possess tiny molecular factories, called chloroplasts, which are in charge of a dye sensitized photochemical redox process - the conversion of sunlight, water and carbon dioxide into carbohydrates and oxygen.
• Inside the nucleus of an atom, a proton is never permanent a proton and a neutron is never permanently a neutron. They keep on changing into each other. A neutron emits a pi meson and become proton and a proton absorbs a pi meson and become a neutron.

Neutron → proton + pi meson

Proton + pi meson → neutron

• The proton and neutron masses are so similar; they differ only by the replacement of an up quark with a down quark.
• The forces that bind the quarks together to form a proton or a neutron are so strong that it is proved very difficult if not impossible to obtain an isolated quark. As we try to pull them out of the proton or neutron, it gets more and more difficult. Even stranger is the suggestion that the harder and harder if we could drag a quark out of a proton the strong force gets bigger and bigger – rather like the force in a spring as it is stretched causing the quark to snap back immediately to its original position. However, now it has been revealed that experiments with large particle accelerators indicate that at high energies the strong force becomes much weaker, and one can observe an isolated quark.
• The faster you move, the shorter and heavier you are. And that is the theory of relativity.
• Space has three dimensions, we mean that it takes three numbers to specify a point. If we add the time, then space becomes space-time, with four dimensions.
• When a wave source moves toward an observer, its waves appear to have a shorter wavelength. If the wave source moves away, its waves appear to have a longer wavelength. This is called the Doppler effect.
• Ordinary matter is made of atoms; atoms are made of nuclei, nuclei made of quarks.
• Gravitational force is a purely attractive force which keeps the planets in orbit around the sun and the moon in orbit around the Earth.
• All the known particles in the universe belong to one of two groups, Fermions or bosons. Fermions are particles with integer spin ? and they make up ordinary matter. Bosons are particles with integer spin 0, 1, 2 and they act as the force carriers between fermions.
• Sun and other stars all emits approximately a black body radiation filling up the universe giving a concrete evidence for the Stefan - Boltzmann law i.e., power radiated per unit area is proportional to the fourth power of their temperature and the proportionality constant is Stefan's constant.
• Since energy divided by (speed of light) × (speed of light) is mass, a little mass goes an extremely long way in producing large energy.
• The biological oxidation of organic molecules results in the formation of utilizable energy molecules (adenosine tri-phosphate) in all living cells.
• Since the graviton has no mass of its own, the gravitational force of attraction between the sun and every planet is long range.
• A force (proportional to a quantity called their charge and inversely proportional to the square of the distance between them) pulls the electrons towards the nuclei to form neutral atoms.
• Each quark possess baryon number = 1/3: the total baryon number of the proton or the neutron is the sum of the baryon numbers of the quarks from which it is composed.
• Among the leptons the electron is a stable object and muon (that has a mass 207 times larger than an electron) and the tauon (that has a mass 3,490 times the mass of the electron) is allowed to decay into other particles.
• The uncertainty in the position of the particle times the uncertainty in its velocity times the mass of the particle is never smaller than a certain quantity, which is known as Planck's constant.
• A rotating neutron star (a tiny, burnt out star) generates regular pulses of radio waves.
• Any light from a distant object would converge as it passes around the galaxy. When we gaze at the distant galaxy, we see a ring like pattern called Einstein ring, an optical illusion caused by general relativity.

The Four Fundamental Forces of Nature are Gravity, Electromagnetism, Weak Nuclear force and Strong Nuclear force.

1. Gravity: This is the weakest of the four; it acts on everything in the universe as an attraction. And if not for this force, we would go zinging off into outer space and the sun would detonate like trillions upon trillions of hydrogen bombs.
2. Electromagnetism: This is much stronger than gravity; it acts only on particles with an electric charge, being repulsive between charges of the same sign and attractive between charges of the opposite sign. More than half the gross national product of the earth, representing the accumulated wealth of our planet, depends in some way on the electromagnetic force.
3. Weak nuclear force: This causes radioactivity and plays a vital role in the formation of the elements in stars. And a slightly stronger this force, all the neutrons in the early universe would have decayed, leaving about 100 percent hydrogen, with no deuterium for later use in the synthesizing elements in stars.
4. Strong nuclear force: This force holds together the protons and neutrons inside the nucleus of an atom. And it is this same force that holds together the quarks to form protons and neutrons. Unleashed in the hydrogen bomb, the strong nuclear force could one day end all life on earth.

• Since the Planck's constant is almost infinitesimally small, quantum mechanics is for little things.
• Associated to each charged lepton, there are three distinct kinds of neutrinos:

1. the electron neutrino
2. the muon neutrino
3. the tauon neutrino

• The 4 dimensional fabric of space-time is simply the lowest energy state of the universe. It is neither empty nor uninteresting, and its energy is not necessarily zero As a remarkable consequence of the uncertainty principle of quantum mechanics (which implies that certain pairs of quantities, such as the energy and time, cannot both be predicted with complete accuracy) the empty space is filled with what is called vacuum energy.
• No spatial or time interval shorter than the Planck values exists:

1. length → Planck length
2. time → Planck time 

• c is not just the constant namely the maximum distance a light can travel in one second but rather a fundamental feature of the way space and time are married to form space-time.
• In any closed system like universe: randomness or entropy never decreases with time.
• neutrinos only feel the weak force.
• By the wave-particle duality of quantum mechanics, light can be regarded as both a wave and a particle.

In phase → wave crests and troughs reinforce each other.

Out of phase → wave crests and troughs cancel out.

• Light waves are emitted or absorbed only in discrete quanta, whose energy is proportional to their wavelength.
• Black hole is a region of space-time. According to the theory of relativity, nothing can travel faster than light. Thus if light cannot escape, neither can anything else; everything is dragged back by the gravitational field.
• Energy can neither be created nor destroyed; it can only be transferred from one form to another.
• Chandrasekhar limit (1.4 times the mass of the sun) is the maximum possible mass of a stable cold star, above which it collapses into a cosmic body of extremely intense gravity from which nothing, not even light, can escape.
• The energy above which (Grand unification energy), the electro-magnetic force, weak force, and strong force become indistinguishable from each other.
• The distance — and the path — that a body travels, looks different to different observers.
• The wavelength of a wave is the distance between successive peaks or troughs.
• Faint light means fewer photons.
• Wormholes provides shortcuts between distant points in space.
• In more than three spatial dimensions, planetary orbits would be unstable and planets would either fall into the sun or escape its attraction altogether.
• Neutron stars are the fastest spinning objects known in the universe.
• The decrease in frequency of light from distant galaxies due to the Doppler effect, indicate that they are moving away from us.
• The universe was in perfect symmetry before the big bang. Since then, the universe has cooled and expanded, and hence the four fundamental forces of nature and their symmetries have broken down. Today, the universe is horribly broken, with all the forces split off from each other.
• Electric and magnetic fields turn into each other in a wavelike motion, creating an electromagnetic field that travels at the speed of light.
• At Planck length, space-time becomes "foamy," with tiny bubbles and wormholes appearing and disappearing into the vacuum.
• The information swallowed by a black hole is forever hidden from the outside universe, and is never revealed until the black hole evaporates and completely disappears (i.e., All one could say of the gravitational monster what the poet Dante said of the entrance to Hell: "All hope abandon, ye who enter here." Anything or anyone who falls through the black hole will soon reach the region of infinite density and the end of time). 
• Accelerated massive bodies give off gravitational waves just as bound electrons in an atom emit electromagnetic radiation.
• Speed of light is the limiting velocity in the universe, unaffected by the movement of its source and independent of all observers.
• Solids, liquids, and gases frame up the three familiar states of matter, but plasma (a gas of ionized atoms) form the fourth state of matter.
• The laws of physics in an accelerating frame remain equivalent to the laws in a gravitational field. 
• The laws of physics remain unchanged under the combination of operations known as C, P, and T (C → changing particles for antiparticles. P → taking the mirror image so left and right is swapped for each other. T → reversing the direction of motion of all particles — in effect, running the motion backward).
• The size and shape of the black hole depends only on its mass, charge and rate of rotation, and not on the nature of the star that had collapsed to form it.