universe for high school students

Universe

The most incomprehensible thing about the Universe is that; it is comprehensible.

- Albert Einstein

The Universe is comprehensible because it is governed by scientific laws; that is to say, its behaviour can be modelled.

- Stephen Hawking

Part -I• How and Where did the Universe come

from and what awaits its final fate.

Part –II• Human Journey in understanding

Universe since last 3000 years

Part –I

How and where did the UniverseUniverse come from and what awaits its final fate.

The Magnitude of our Universe

The earth

Diameter at the equator - 7,930 miles

Av distance to the Sun - 93 million miles(1AU)

Average Density - 5.52 g per cu cm

Mass (M⊕) - 5.9722 x 1024 kg

The Sun

• Diameter at the equator - 864,000 miles• • Average Temperature - 5,500° C

• Temperature at core - 15,000,000 ° C

• Mass - 332,900 M⊕

• Density - 1.4 g per cu cm

Solar system

Planets and their satellites,

asteroids and other rocky objects, and an incalculable number

of comet like objects, some more than 1 trillion miles from the Sun,

make up the solar system.

Our planet

Our Sun with its Neighbours

There are Stars in our Galaxy more than two thousand times the diameter of Sun

OUR GALAXYOUR GALAXY

Our galaxy – milky way• Diameter - 100,000 Light

years• Thickness - 1,000 Light years • Stars it contains > 100,000,000,000 (100

bn)

• Mass - 1.5x1021 M⊕

(1 Light Year = 10 trillion km (1x1013 km )

Our UniverseOur Universe

Our universe

• Came into existence – 13.7 bn years ago

• Diameter – 46,600,000,000 (46.6 bn) light years.

• Galaxies it contains > 100,000,000,000 (100 bn)

• Stars it Contains > 100,000,000,000,000,000,000

What universe consist of

The universe is everything that

exists, from the smallest Particles to the largest ones,

together with all matter and energy. The universe includes visible and

invisible things.

What universe consist of

The universe, marvellous in its

majesty, is an ensemble of > 100 billion galaxies. Each

of these galaxies (which tend to be found in large groups) has 100 billion

stars. These galactic concentrations surround empty spaces, called cosmic

voids.

Where did this Universe come from ?

Big BangBig Bang

Big Bang

• Time: Zero Temperature: Infinite

• Size : Infinitesimal

Though we now know about the Universe from a billionth of a second

after big bang, We do not know much about the very moment of big bang.

Big Bang

• Time: 10-43 sec Temperature: 1032 oC

Universe's inflation begin

Expansion

Time: 10-38 sec Temperature: 1029 oC

universe Increases in size

more than a trillion, trillion, trillion times every

fraction of a second. The expansion of the universe and the division of its forces

begin.

Forces appearTime: 10-12 sec Temperature:

1015 oCGravity,

electromagnetic force, strong nuclear force

and weak nuclear force appear.

Protons and Neutrons AppearTime: 10-4 sec Temperature:

1012 oCProtons and neutrons

appear, formed by threequarks apiece. Light is trapped within

the web of particles, the Universe is still dark

Dark mater

Time: 1 sec Temperature: 1010 oC

The neutrinos separate from the initial

particle through the disintegrationof neutrons. Though having extremely

little mass, the neutrinos might be the greatest

part of the universe's dark matter

Atom Time: 5 sec Temperature:

109 oC

The electrons and their antiparticles,

positrons, annihilate each other until thepositrons disappear. The remaining

electrons form atoms in company with proton.

Elements FormTime: 3 sec Temperature:

107 oCThe nuclei

of the lightest elements, Hydrogen and

Thereafter Helium, form. Protons and neutrons unite to form the nuclei of

atoms

Light Escapes

Time: 380,000 Yrs Temperature: 2700 oC

Photons (particles of light) escapes from the Dense Web of

particles and could now pass freely through the Universe.

GRAVITATION GIVES SHAPE TO STARS

GalaxiesTime: 500 million yrs Temp: -

243 oCGalaxies

acquire their definitiveshape. Gravitation gives shape

to islands of millions and millions of stars from masses of gases . The stars

explode as supernovas and disperse heavier elements, such as carbon.

Solar systemTime: 9 Billion Yrs Temperature:

-258 oC

Solar system emerged. A mass of gas

and dust of supernova collapsed until it gave rise to the Sun. Later the planetary

system was formed from the leftover material.

Solar systemTime: 9.1 Billion Yrs Temp: -

265 oC

Like the rest of the planets, the Earth

formed of material that remained After the formation of the solar system.

Expansion Continues

Time: 13.7 Billion Yrs Temp: -270 oC

Universe continues to expand. Temperature near

big bang has cooled to 2.7 deg K

What awaits The future of universe ?

Future of Sun (and other stars up to 08 Solar Mass)

After five billion years Supply of hydrogen will be exhausted,

and will transform into a red giant, expanding

until it swallows Mercury. At its maximum size, it

may even envelop the Earth and condenses into a white dwarf.

SUPER NOVASUPER NOVA

The star swells and heats up. The

heavy core of iron explodes as SUPERNOVA and its dense core turns into a

NEUTRON STAR.

Future of other Stars ( more than 8 solar masses)

Black hole

When the fusion energy is unable to balance

its intense gravitational force BLACK HOLE is formed, Its gravitation

captures even light.

Future of other Stars ( more than 20 solar masses)

Future of Stars

In the scale of hundreds of billion years

all the stars in the universe willflicker out after their nuclear fuel is

exhausted.

Future of Matter

1032 years. Atoms disintegrate,

Protons and neutrons decay, electrons and neutrinos separate.

Future of Universe

The big bang Theory helped solve the enigma of the

early moments of the universe. What is yet

to be resolved is the mystery surrounding its future.

The Mystery

To unravel this mystery, the total mass

of the universe must be known, but that figure has not been reliably

determined.

Critical Density

For the universe

to reverse expansion, An average density of more

than 10-29 gm /cm3 is required

Open UniverseIt appears

that the mass of the universe is far too little to stop

its expansion. If this is the case, the universe's present growth is merely the

last step before its total death in complete

darkness. Universe dies as temperatures in the entire universe drops to near

absolute zero.

Closed Universe

If the universe had more than critical

mass, it would expand until reaching a point where gravity stopped the expansion.

Big Crunch, will culminate in

an infinitely small, dense, and hot spotsimilar to the one from which the

universe was formed

Part –IIHuman Journey in understanding Universe

since last 3000 years

If I have seen farther than most, it is because I have stood on the shoulders of

giants.

- Isaac Newton

At about 1000 BC people believed:

• Stars were bonfires lit by other tribes in the sky.

• Universe was a flat plate resting on the shell of a giant turtle.

• Later, Egyptians thought that the Sun was a ball of fire, and they had no idea what the fuel was.

Understanding Universe• 640 BC Greek philosopher Thales Named as

the world’s first mathematician predicted solar eclipse accurately.

• 450 BC - The beginning of Physics Democritus said: – Nothing exists except Atoms and Empty Space, – Everything existing in the Universe is the result of

chance and necessity.• 350 BC - Greek philosopher Aristotle

– Believed earth was a sphere and not a flat plate.– Believed universe existed and would exist forever.• Philosopher Anaxagoras Thought that the Sun

was a red hot iron.

Understanding Universe

• 300 BC Euclid Postulated laws of Geometry

• 212 .B.C.Eratosthenes Measured the circumference of earth.

• Philosopher Thales – Water is the primary and ultimate element


• Philosopher Anaximander – There exist primary building block of matter but it can’t be water.

• Philosopher Parmenides – Matter can neither come nor pass away.

• Philosopher Empedocles – There are only few basic ingredients in the Universe, and everything is combination in a multitude of ways.


• 2nd Century AD- Ptolemy Thought the planets orbited around Earth.

• 1514- Copernicus – Put the Sun in the centre and planets

around it.– Stars are fixed in its position, meaning a

static universe• Johannes Kepler

– That planets orbit is not circular but elliptical.– Formulated laws of planetary motion

Understanding Universe• 1580s- Galileo Galilee.

• First to aim a telescope skyward. • Developed the formula used to calculate the

free fall of any object toward earth.• Relation between distance between distance,

time and speed.• Object under free fall, fall faster over time and

the acceleration is constant.• Free fall object irrespective of its weight

touches the ground at the same time.• Concluded that object under motion will

neither slow down or speed up but continue for ever.

Thus contradicting Aristotle’s belief that the object’s natural state is rest.


• 1676- Ole Christensen Roemer Discovered that light travels at a finite but

very high speed.•


• 1687- NEWTON'S EQUATION – Formulated mathematical relation for

gravitational force between masses. F = G m1x m2

r2

– Was the father of “infinitesimal calculus”


– 1700 – Galvani Invented battery.

– 1781- Philosopher Immanuel Kant Argued that universe had a beginning.

– 1808 – John Dalton Declared that the basic unit of chemical element is atom and each chemical atom has its own weight.

– 1815- William Prout – All matters are made up of Hydrogen.

Understanding universe

• 1800 – Scientists realised that Sun could not have stayed hot for a long time had it been a hot iron.

• 1809 - AstronomerJean Baptiste Joseph Delambre Reported the time for light to travel from the Sun to the Earth as 8 minutes and 12 seconds

• Around the same time Darwin pointed out that the earth had to be hundreds of millions year old.


– 1820- Hans Christian Discovered a connection between electricity and magnetism.

– 1820’s –Ampere Found the mathematical relation between electricity and magnetic field.

– 1823 – Philosopher Heinrich Olbers Stars were not been shining for ever, but was

turned on in a finite past. – 1830 – Michael Faraday

• Made laws of electrolysis.• Invented electric motor.


• .. 1867 - Dmitri Mendeleev

Created the first Periodic Table of elements.


– 1850 – John Waterston A School teacher. Showed that chemical energy could have fuelled Sun only for some 10,000 years.

– 1853 - John Waterston Proposed that the Sun is falling under its own weight and producing heat.

– 1860 – William Thomson Calculated the Sun’s age as 100 million with the idea of shrinking Sun.

– 1860 – James Clerk Maxwell Established existence of electromagnetic waves moving through space at a finite velocity of 3 x 10 8

m/s.


• 1865- James Clerk Maxwell Described the theories of electricity and magnetism.

• 1874 – George Johnston Stony Coined the term “Electron

• 1887-Albert Michelson Discovered that light traveled at same speed irrespective of the speed and direction of the one who measures it.

• 1887-1905- Dutch Physicist Hendrik Lorentz Attempted to explain object contracting and clocks slowing down when they move through ‘ether’ or empty space.


– 1895 – Rontgen Accidentally discovered X-Rays.– 1986 – Henri Becquerel Discovers radioactivity.– 1896 – Marie and Pierre Curie Discovered

release of energy associated with radioactivity– 1897 – William Thomson Refined his calculation

and said Sun was 25 million years old.– 1897 – JJ Thomson Discovered that atoms have

inner structure, they contain electron.– 1897 – Earnest Rutherford Unravelled atomic

structure and radioactivity.


– 1900- German scientist Max Plank Light and other waves energy emission is in packets called ‘quanta’ and not in any arbitrary rate.

– 1904 - Ernest Rutherford Realized that radioactivity could a source of energy for Sun.


1905 – Albert Einstein –Explained photo electric effect–Formulated Theory of Special Relativity, with that came E=Mc2

Understanding Universe Einstein’s Relation. 1905-1915Special Relativity Between Time-Space Time can beat at

different rates, depending on how fast one is moving. It means that the speed of light appeared same for all observers.

Relativity Principle Between Mater-energy Energy and mass are interchangeable, to be precise at E=MCE=MC22. If an object increases its mass, its energy increases, and vice versa. i.e. mater is condensed energy.

Equivalence Principle Between Acceleration-Gravity law of nature in an accelerating frame are equivalent to the laws in a gravitational field. Gravity, according to this theory, is a distortion of space that determines whether one object rolls toward another.

General Relativity Between Mater-Energy and Time-Space The presence of mater-energy determines the curvature of the space-time surrounding it. Gravity is a result of this curvature.

Understanding Universe • 1910 – JJ Thomson Demonstrated the

existence of Electron. • 1911 – Ernest Rutherford Showed that

atoms are made-up of positive charged Nucleus around which Electrons orbit.

• 1913 – Rutherford Stated that the enormous temperatures Sun could make elements change from one to another, which mightbe stable on earth.

Understanding Universe • 1920 – Francis Aston Found that the

atomic mass of Helium was one part in 120 less than four Hydrogen atom.

• 1920 -Satyendra Nath Bose Laid the foundation for new quantum mechanics of Schrodinger, Heisenberg.

• 1920 – Sir Arthur Erdington Stated that Sun burns Hydrogen into Helium producing heat and light.

• 1939 – Hans Bethe Explained “CNO” cycle responsible for Sun’s energy production.

Understanding Universe • 1926- Werner Heisenberg Formulated uncertainty

principle, by which – to predict a future position and velocity of a particle, one

should be able to measure present position and velocity. – It is impossible to predict the position and velocity of a

particle in space, – More precisely one parameter is measured, less precisely

the other can be measured.

• 1930 – Wolfgang Pauli Postulated that beta decay has to be associated with emission of a particle with trifling mass.

• 1930 – Subramaniam Chandrashekar Discovered the limiting mass of the star in formation of white dwarf and neutron star.

• 1932 – James Chadwick Discovered that the nucleus contained another particle called the Neutron which has almost same mass of a proton but no electric charge.

Understanding Universe Edwin Hubble

in 1929 observed that the universe is expanding.

Which means at some point of time earlier all matter was at one

point and its density was infinite. This discovery brought the question of the

beginning of the universe into the realm of science.


• 1940s, George Gamow Developed the idea that the universe began with a primordial explosion.

• 1960s- Arno Penzias and Robert Wilson Accidentally detected A consequence of Big Bang in existence of uniform background radiation in space.

• 1960. Peter Higgs -predicts the existence of a new particle, the Higgs boson.


• 1969 – Murray Gell-Mann Discovered Particle elementary than proton and neutron namely QUARK.

• 1970 – Scientists briefly contemplated if the Sun was still shining, which was quickly falsified.

• 1970-2000 – Standard model of ‘Particle Physics’ contributed by many physicsts.

• 1998 - Saul Perlmutter, Brian Schmidt, and Adam Riess discovered accelerating expansion of the Universe

Understanding Space and Time

Understanding Space and Time– Aristotle

•Stared that, there is a absolute Stared that, there is a absolute position in spaceposition in space..

– Newton – There is no absolute state of rest.•Stated that, it cannot be determined Stated that, it cannot be determined

if two events took place in different if two events took place in different times occurred in the same position.times occurred in the same position.

– Both Aristotle and Newton believed in absolute time.•Agreed that, one can unambiguously Agreed that, one can unambiguously

measure the interval of time between measure the interval of time between two events in space, and the time two events in space, and the time would be same whoever measures it,would be same whoever measures it, (provided they used a good clock)(provided they used a good clock)


– Maxwell – Light should travel at fixed speed.

– Albert Michelson Light travels at same speed irrespective of the speed and direction of the one who measures it.

– Hendrik Lorentz Object contracts and clocks slow down when they move through ‘ether’.


• Einstein– Abandoned the idea of ‘ether’ and absolute time to explain the speed of light. – It means that the speed of light appeared It means that the speed of light appeared

same for all observers.same for all observers.– The energy the object has due to motion The energy the object has due to motion

will add to its masswill add to its mass

Understanding Space and TimeThe Consequence of Einstein’s Relativity.

– If a pulse of light is sent from one place to other.– All observers will agree on the time for the

journey.– All observers will not agree on the distance– Since speed of light is the distance travelled/time

taken. – As per relativity speed of light is same for all

observers. – So, now all observers must disagree over the

time taken. – Thus the theory of relativity put an end to

absolute time.

I am finished with Space and Time for now

We each exist for but a short time, and in that time explore but a small part of the whole Universe. We wonder, we seek answers living in the vast world that is by turn kind and cruel, and gazing at the immense heavens above, people have always asked multitude of questions: How can we understand the world in which we find ourselves? How does the Universe behave? What is the nature of reality? Where did all this come from? Did the Universe need a creator? Most of us do not spend most of our time worrying about these questions. But almost all of us think about them some time or other.

- Stephen Hawking

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QuoteQuote

• Hyper Space – by Michio Kaku

• A Brief History of Time – by Stephen Hawking

• Articles on Astrophysics from Encyclopedia Wikipedia

• Illustrated Science Library – Britannica

• The God Particle - Leon M. Lederman

• The Grand Design - Stephen Hawking

• Euclid’s Widow - by Leonard Mlodinow

• The Human Touch – by Michael Frayn

• Absolutely Small - Michael D Frayer

• Public lectures and colloquium of Prof Stephen Hawking

• Zero - Cherles Seife

• Neutrino - Frank Close

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References:

Thanks for Listening