Last time I was going through this book “Astrophysics for people in a hurry” and I thought that it will be useful if I share about this to other people also. Everyone seems to be interested about cosmos nowadays, and every YouTube videos are just describing about those things. But a relevant material was what was less found. So I am publishing this as a relevant material.
“Universe is under no obligation to make sense to you.”
- Einstein’s general theory of relativity in 1916, gives our modern understanding of gravity in which the presence of matter and energy curves the fabric of space and time surrounding it.
- Types of forces were known and was found that weak forces control radioactive decay, strong forces binds the atomic nucleus, electromagnetic forces binds molecules and gravity binds the bulk matter.
- Trillionth of a second has passed since the beginning.
- Forces that keeps 2 quarks grow stronger, the more you separate them as if they were attached by some sort of sub-nuclear rubber band.
- As the cosmos continued to expand and cool, growing larger than the size of our solar system, the temperature dropped rapidly below a trillion degrees kelvin.
- A millionth of second has now passed since the beginning.
- Large hadron collider-: In Switzerland, the European particle physics collaboration uses a large accelerator to collide beams of hadrons in a certain temperature to recreate this very conditions.
- During the hadron era, ambient electrons could no longer invoke E=mc² to manufacture quark antiquarks pairs.
- By now, 1 second of a time has passed.
- The universe has grown to a few light years across about the distance from the sun to its neighboring starts.
- 2 minutes have now passed since the beginning.
- For the 1st billion years, the universe continues to expand and cool as matter gravitated into the massive concentration, we call galaxies. Nearly 100 billion galaxies were formed.
- Those stars with more than about 10 times the mass of the sun achieve sufficient pressure and temperature in their cores to manufacture dozens of elements heavier than hydrogen, including those that of contain planets. If these elements remained where they were, it would be completely useless. But the explosion of high mass stars scattered those things throughout the galaxy.
- After 9 billion years of such enrichment, in an undistinguished part of the universe(the outskirts of the Virgo superclusster) in an undistinguished galaxy(the milky way) in an undistinguished region( the Orion arm), an undistinguished star(the Sun) was born.
- Before 63 million years ago, a comet destroyed the life of dinosaurs.
- Then what happened before that? Well, nobody knows. And what is happening right now? Is this just a computer simulation by aliens? We can’t say anything.
- Before newton, no-one had assumed that the laws of physics in heaven (different galaxies) were same as in earth. Later newton discovered the universal gravitation constant formula and we all know after that.
- An attempt to communicate with aliens was done in the 1970s with pioneer 10 and 11 and Voyager 1 and 2. Voyager consisted of a gold record album containing diverse sounds from mother earth, including the human heartbeat, what “songs”, and musical selection from around the world, including the works of Beethoven and Chuck Berry. But no reply did came.
- If you do math, you can determine that the star’s luminosity is steeply dependent on big G. i.e. if big G had been even slight, different in part then energy output of sun would have been more variable.
- Now let’s talk about matter that constitutes the universe.
- Ordinary matter is what we all are made up of. It has gravity and it interacts with light.
- Dark matter is substance that has gravity but doesn’t interact with light (so either it moves faster than light or it is something from higher dimensional world).
- Dark energy is mysterious pressure in vacuum that acts in opposite direction of gravity forcing the universe to expand and cool faster than it should be.
- Quasars are the super-luminous galaxy cores whose light has typically been travelling for billions of years across space before reaching our telescope. Quasars may be composed of ordinary matter or dark matter, still not clear, so they’re under research from 1980s.
- In either case, whether ordinary of dark, where there is mass, there’s gravity and where there is gravity, there is a curved space, according to the general theory of relativity.
- Cosmic rays composed of hydrogen, protons ET car moving with nearly equal to the velocity of light or 99.9999999999999 percent of velocity of light.
- We’ve been waiting for a century for someone to tell us why 85% of gravitational force arises from substance that we don’t even know and they don’t interact with our matter of energy.
- A short poem-:
Look onto the stars to teach us,
how the master thoughts can reach us; ~
each one follows Newton’s Laws,
Silently along its path.
- Could dark matter be the effect of forces from another dimension?
- Neutrinos were first predicted like dark energy and later were found, we hope the same for dark matter.
- By theoretical physics, we found that the universe was expanding faster than it should be. Now comes the helpful thing that Einstein did mistake by calling it as blunder of his life. It was lambda in the Einstein’s general theory of relativity.
- It is found that dark energy is responsible for the 68% of the mass-energy in the universe. Dark matter comprise 27% with regular matter just making 5%.
- Critical density can also be said as the mass-energy density required just barely halt the expansion of universe.
- The conditions that can be arise from the above equation are as follows
1) Ω <1 universe will expand forever in all direction
2) Ω=1 =>universe will expand but not as before, and it will now follow all the rules we learned in geometry in high school about parallel lines.
3) Ω>1=>parallel lines converges and the universe curves back onto itself, ultimately re-collapsing into the fireball whence it came at first.
- Until now the maximum value of omega is recorded to be 0.3000.
- So there is still no good basis to describe about dark energy and the theory of dark energy needs to come up.
- There is a good relationship between elements occurring in periodic table and the planets. These elements formed in earth’s crust are somewhat fall from those planet in earth as it seems.
- If you don’t understand the spherical case, then you can’t understand the basic physics of the object.
- Spheres in nature area made by faces such as surface tension that want to make the object smaller in all directions.
- Using freshman level calculus, you can show that the only shape that has the smallest surface area for an enclosed volume is a perfect sphere.
- For large cosmic objects, energy and gravity turn objects into spheres.
- Gravity is the force that serves to collapse matter in all directions, but gravity doesn’t always win-chemical bond of solid objects are stronger. Himalayas grew against the force of earth’s gravity because of the resilience of the crustal rock.
- Earth feels spherical and smooth from space.
- Earth’s mountain are also smaller when compared with some other mountain in solar system because of high gravity at earth. The largest on mars is Olympus Mom is 65000 feet tall and 300 miles wide.
- If a solid object has low enough surface gravity, the chemical bonds in its rocks will resist the force of their own weight. When this happens, almost any shape is possible. For example-: Photo and Demos, potato-shaped moon of Mars.
- Our galaxy is flatter than the flattest flapjacks ever made.
- But the Milky Way isn’t a sphere but it may have been once a sphere.
- We can assume that galaxy was once a big, spherical, slowly rotating ball of collapsing gas. During the collapse, it spin faster and faster, just as spinning figure skaters do when they draw their arms inward to increase their rotation rate. The galaxy naturally flattened at pole-pole while the increasing centrifugal force in the middle prevented its collapse.
- Stars that formed within the Milky Way cloud before collapse maintained large, plunging orbits. The remaining gas, which easily stick to itself, like a mid-air collision of 2 hot marshmallows, got pinned at the mid-plane and is responsible for all subsequent generation of stars, including the sun.
- The current Milky Way, which is neither collapsing nor expanding, is a gravitationally mature system where one can think of the orbiting stars above and below the disk as the skeletal remains of the original spherical gas cloud.
- Saturn completes a day in just ten and half hours, its equator revolves at 22000 miles per hour and pole-pole dimension is a full ten percent flatter that its middle and a difference is noticeable even through the small telescope.
- Consider pulsars, who rotate extremes like 4500 raps, its equator would be moving at speed of light. To picture a pulsar, imagine mass of sun packed into a ball, the size of Manhattan. It is same as packing 100 million elephants in your geometry box (even smaller than yours!!!). This means a neutral compressed neutrons with a crazy-high surface gravity will form.
- Under such conditions, a neutron star’s mountain range needn’t be any taller than the thickness of a sheet of paper for you to exert more energy climbing it than a rock climber on earth would exert ascending a 3000 mile high cliff.
- In short, where gravity is high, high places tend to fall, filling low places.
- So pulsars are believed to be the perfect spheres.
- In every direction, we look galaxies recede from us at speed, proportional to their distance which is called Hubble’s Law.
- It’s serious time now!!!
- How to increase milk production on a farm. An expert in animal husbandry might say ‘Consider the role of cow’s diet’. An engineer might say,” Consider the roles of milking machines”. But the astrophysicist will say, “Consider a spherical cow”.
- Radio telescopes help to view the electromagnetic spectrum=gamma rays, x-rays, etc.
- The world’s largest radio telescope, completed in 2016, is called Five hundred meter Aperture Spherical radio Telescope or FAST for short. It is larger in area than 30 football fields. If aliens ever gave us a call, Chinese will be the first to know.
- From a distance our solar system looks empty. If we enclosed it within a sphere then the volume occupied by sun,all planets nd their moons would take upto a little more than one trillionth of the enclosed space.
- The remaining space is not empty. It is filled with chunky rocks, pebbles etc. and the space is also within strong gravitational and magnetic fields.
- Nearly all meteors burn in earth’s upper atmosphere.
- Moon was formed by the action of meteors. Moon may have come out of earth’s iron poor crust.
- Asteroids have mass less than 5% of moon, which is itself barely more than 1% of earth’s mass.
- A simple calculation reveals that most of them will hit earth within a 100 million years. The ones larger than about a kilometer across will collide with enough energy to destabilize earth’s ecosystem and put most of the earth’s land species in risk of extinction.
- But, not to forget that not only asteroids but also comets are risk to our lives.
- If we had eyes that could see magnetic fields, the Jupiter would look 10 times larger thatn the full moon in sky. There is a mantra, i.e fast moving metal probes will generate electrical currents and they retard the space probe’s motion.
- The sun loses material from it surface at a rate of more than a million tons per second. We call this solar wind,which takes the form of high energy charged particles.
- Jupiter has mighty gravitational field and bats out many comets that would enter the inner solar system. So Jupiter is a earth’s big brother allowing 100 million years of peace on earth.
- If there was no Jupiter, it wasn’t sure if you will extinct today or tomorrow.
- From orbit, with unaided eye-you would see smoke rising from oil-field fires in Kuwait at the end of first Persian gulf war in 1991 and smoke from the burning world trade tower center in September 11,2001. Beyond that humans have not done anything interesting which can be identified from 100 miles up from the sky!
- From the orbit of Neptune, earth looks like pale blue dot: probably because of this, no alien has still invaded us.
- But, what if aliens decided to invade the earth. They’ll see our blueness and say that it contains liquid water, so it must be at normal temperature and pressure. They will see carbonic, sulfuric acid and say that we are not intelligent human beings!
- The author says that he gets tensioned that he is saying this and that about the universe, but at this instant someone at African countries is dying because of hunger and malnutrition. He is unhappy with those who don’t help these people when they have lots of money.
- We human beings are nothing from space point of view.
- The more bacterial live in 1cm thatn the whole number of people
|More bacteria live in 1cm than all humans ever born. Now know who is in charge? We or bacteria!!! You may say we are clever and smart-but I say with respect to whom are we clever-with respect to a chimpanzee? A chimpanzee can’t solve simple divisions and multiplications. Now imagine someone who is at ours is to chimpanzee brain ratio. Imagine, they will be learning multivariable calculus from class 1 instead of learning A,B,C!!!!|
- There are more molecules of water in 8 ounce cup than there are cups of water in all world’s oceans.
- There are more stars in the universe thatn grain of sand in any beach,more stars than seconds have passed since earth has formed, more stars than words and sounds ever uttered by all human beings who has ever lived.
- We don’t simply live in the universe, the universe lives within us.
- Shortly after the formation of our solar system, Mars was more wet than earth. So it is possible that Elon Musk will land us on Mars. Meaning, the Homo Sapiens must have first been on Mars and later descended on earth.
- The cosmic perspective simply puts our ego on the ground and makes us humble.
- So be curious about exploring. If in past, everyone was busy with their own business, then we still have been living in Stone Age. There was someone who wanted to explore and now we are here. You may be that next transformer.
- All the best!!!