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Unit 2 Section A
Einsteins Repulsive Idea
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Albert Einstein (1879---1955)
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Do you have any idea about the formation of
our universe before reading this article?
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A human being is part of the whole called
by us universe, a part limited in time and space.
We experience ourselves, our thoughts and
feelings as something separate from the rest. A
kind of optical delusion of consciousness. This
delusion is a kind of prison for us, restricting
us to our personal desires and to affection for a
few persons nearest to us. Our task must be to
free ourselves from the prison by widening our
circle of compassion to embrace all living
creatures and the whole of nature in its beauty.
The true value of a human being is determined by
the measure and the sense in which they have
obtained liberation from the self. We shall
require a substantially new manner of thinking if
humanity is to survive.
---Albert Einstein,
1954
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An Overview of Cosmology

• Objectives
• Develop perspective on the history of human
  knowledge of the universe
• Understand the process of scientific exploration
  of the universe
• Contemplate the current state of astronomy and
  think about future missions

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What is Cosmology?
For thousands of years, astronomers
wrestled with basic questions about the size and
age of the universe. Does the universe go on
forever, or does it have an edge somewhere? Has
it always existed, or did it come to being some
time in the past?
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Our View of the Cosmos - the story of scientific
models
Three scientific revolutions in cosmology
2nd Century Claudius Ptolemy (Physics of
Aristotle) Model Earth-centered Cosmology
16th Century Nicolaus Copernicus (Physics of
Newton) Model Sun-centered Cosmology

20th Century Edwin Hubble (Physics of Einstein)
Model Big Bang Cosmology
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Earth-centered Cosmology Claudius Ptolemy,
100-170 AD
Big idea Earth was viewed as a stationary center
of the universe, with sun, moon, and stars
revolving about it in circular orbits and at a
uniform rate.
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Sun-centered Cosmology Nicholas Copernicus
1473-1543
Big idea Copernican system placed the sun
motionless at the center of the solar system with
all the planets, including the earth, revolving
around it.
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Big Bang Cosmology Edwin Hubble and Albert
Einstein
Big idea The universe had exploded and expanded
from a small, hot, dense state into what we see
today.
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Big Bang Theory
the theory of the cosmic explosion that
marked the origin of the universe. According to
the big-bang theory, at the beginning of time,
all of the matter and energy in the universe was
concentrated in a very dense state, from which it
exploded, with the resulting expansion continuing
until the present. This big bang is dated between
10 and 20 billion years ago. In this initial
state, the universe was very hot and contained a
thermal soup of quarks, electrons, photons, and
other elementary particles. After many millions
of years the expanding universe, at first a very
hot gas, thinned and cooled enough to condense
into individual galaxies and then stars.
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Einsteins Repulsive Idea
History of expansion A rough picture of how
the universe's expansion decelerated, then began
to accelerate. Fate is not known.
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Einsteins Repulsive Idea
This diagram reveals changes in the rate of
expansion since the universe's birth 15 billion
years ago. The more shallow the curve, the faster
the rate of expansion.
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Some theorists think the Universe is filled
with a mysterious dark energy, a sort of negative
gravity.
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The Hubble Space Telescope recently
captured light from a supernova located farther
from Earth than any previously seen. The
finding has bolstered cosmological models for the
universe's expansion and a mysterious dark
energy pervading it. The supernova, or exploding
star, is located 10 billion light-years from
Earth.
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Normal Matter 4
Dark Energy 73
Dark Matter 23
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Conclusions

• Big Bang model describes our current
  understanding of the universe.

• New discoveries, such as dark matter and
  accelerating
• expansion (Dark Energy), lead us to refine our
  model.

• Science is an ongoing process - forcing us to
  test
• our model through prediction and observation.
  The
• more tests it passes, the greater is our
  confidence in it.

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New technology has made cosmology one of the
most exciting sciences today, but not all the
answers have been found. Watch the video segment
the Gravity and the Expanding Universe and answer
the following two questions.

1. What does it mean to say that the universe is
   accelerating?
2. What are the difficulties in studying and
   understanding the universe?

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Einsteins Repulsive Idea
The scientific style is dictated by the
purpose of the type of writing. The scientist or
engineer will generally write to describe a
phenomenon, an experiment or a process, or to
explain a theory. Hence they belong to the
category called exposition. In this text, the
author explains Einsteins repulsive idea and its
relationship to the latest research of expanding
universe.
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Key words in the text
cosmological term
general relativity
gravity and antigravity
supernova
Hubble Space Telescope
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Relativity

• After all, his special and general
  relativity theories made the astonishing
  assertion that time, space and matter could be
  squeezed and stretched like so much India rubber.
  (Para.1)

Special Relativity ---We cannot catch up with
light. ---Mass is a form of energy. E m c2
General Relativity GR encompasses gravity and
describes the expanding universe and black holes.
Einstein in 1905, at the age of 26
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Einsteins Repulsive Idea
The trouble was that some sort of
antigravity forceEinstein called it the
cosmological term was required to make the
predictions of general relativity match what
astronomers believed the actual universe looked
like. (Para. 1)
Question Why did Einstein hypothesize the
cosmological constant? Why did he later discard
it?
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Einsteins Repulsive Idea
The great physicist was hugely relieved when
the discovery of the expanding universe in the
1920s let him cross out what he declared was my
greatest blunder. (Para. 1)
Question 1. Why did Einstein call his
cosmological constant his greatest blunder? 2.
What is the assumption taken from Hubbles
discovery and recent astronomical data?
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Using the Hubble Space Telescope to find
and study a distant supernova, astronomers from
two rival research teams have jointly gathered
the strongest evidence yet that the expansion of
the universe is actually speeding up. (Para. 2)
Hubble Space Telescope (HST) the first
general-purpose orbiting observatory, Named after
American astronomer Edwin P. Hubble. The Hubble
Space Telescope was launched on April 24, 1990.
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The first hint came a couple of years ago,
when two independent teams of astronomers tried
to calibrate the cosmic expansion using Type Ia
supernovas, a kind of exploding star whose
intrinsic brightness is highly consistent.
(Para. 4)
Supernova a stellar explosion that produces an
extremely bright object made of plasma that
declines to invisibility over weeks or months.