Transcript Slide 1

Origins of the Universe
The Big Bang Theory
•Until 100 years ago, scientists believed nothing ever changed in outer space.
The Big Bang Theory = everything in the universe came from a single starting point,
approximately 13.7 billion years ago.
Although there are other theories about the beginning of the universe, much scientific
evidence supports the Big Bang theory.
1. Evidence For The Big Bang Theory
1)Expanding Universe.
a) Using powerful telescopes, astronomers like
Edwin Hubble discovered many new celestial
bodies, and observed that everything in the
universe was moving further apart.
b) The universe expands like baking bread;
galaxies and other celestial objects are like
raisins in the dough, moving apart as the bread
bakes.
Horton Hears a Who:
Part 1
http://www.youtube.com/watch?v=B0qZ4V53EV4
Part 2 http://www.youtube.com/watch?v=3BsiN8SxUMM&feature=mfu_in_order&list=UL
c) Once astronomers realized everything was moving away from everything else,
they realized the universe might have originated from a single point.
2) Objects in the Universe are Red-Shifting
a)Light, like all forms of electromagnetic radiation, travels in waves. Objects in space give
off many different forms of radiation.
b)Like the sound of an ambulance siren changes as it passes you, light from stars exhibits
red-shift, indicating speed and direction of motion.
As the ambulance approaches,
the sound waves from its siren are
compressed towards the observer.
The intervals between waves
diminish, which translates into an
increase in frequency or pitch.
As the ambulance recedes, the
sound waves are stretched relative to
the observer, causing the siren's
pitch to decrease. By the change in
pitch of the siren, you can determine
if the ambulance is coming nearer or
speeding away.
If you could measure the rate
of change of pitch, you could also
estimate the ambulance's speed.
5) Doppler Effect
= a change in pitch of a sound made by an object moving toward or away from another
object.
1.Discovered by Christian Doppler (Austrian mathematician and physicist)
2.Change in pitch is created by a shift in the frequency of sound waves.
3.The sound of an object that is NOT moving sends out waves evenly in all
directions (See A). The pitch of the sound is the same from all positions because the
wave frequency is the same.
4.The pitch of an approaching vehicle is higher than normal: the compressed, higher
energy and frequency waves create a higher pitch, as seen in B.
5.The pitch of an vehicle that is moving away is lower than normal: the longer, lower
energy and frequency waves create a lower pitch, as seen in C.
C
i) An object at
rest sends sound
waves evenly in
all directions
i) As an object
approaches, the
sound waves in
front of the object
become
compressed. The
waves increase in
frequency, energy,
and results in a
higher pitch.
A
A
B
A
c) A spectroscope analyzes the unique spectrum of a star, which astronomers can
analyze to discover the direction and amount the light has shifted.
A red shift means the wavelength is
getting longer, and the star is moving
away from us.
Blue shift is the opposite; the star is
getting closer.
Cosmic Background Radiation= the
energy left over from the Big Bang.
http://apod.nasa.gov/apod/ap050925.html
WMAP Resolves the Universe
This radiation was mapped by the COBE and WMAP explorations.
Credit: WMAP Science Team, NASA
Explanation: Analyses of a new high-resolution map of microwave
light emitted only 380,000 years after the Big Bang appear to
define our universe more precisely than ever before. The eagerly
awaited results announced last year from the orbiting Wilkinson
Microwave Anisotropy Probe resolve several long-standing
disagreements in cosmology rooted in less precise data.
Specifically, present analyses of above WMAP all-sky image
indicate that the universe is 13.7 billion years old (accurate to 1
percent), composed of 73 percent dark energy, 23 percent cold
dark matter, and only 4 percent atoms, is currently expanding at
the rate of 71 km/sec/Mpc (accurate to 5 percent), underwent
episodes of rapid expansion called inflation, and will expand
forever. Astronomers will likely research the foundations and
implications of these results for years to come.
(http://apod.nasa.gov/apod/ap050925.html)
http://curious.astro.cornell.edu/question.php?number=468
Types of Universe Models
1. Static Universe
2. Expanding Universe
3. Oscillating Universe
Static Universe
http://en.wikipedia.org/wiki/Static_universe
A static universe, also referred to as a "stationary" or "Einstein" universe, is a
model in which space is neither expanding nor contracting. Albert Einstein proposed such
a model as his preferred cosmology in 1917[citation needed]. He added a positive cosmological
constant to his equations of general relativity to counteract the attractive effects of gravity
on ordinary matter, which would otherwise cause the universe to either collapse or expand
forever. This motivation evaporated after the discovery by Edwin Hubble that the universe
is in fact not static, but expanding; in particular, Hubble discovered a relationship between
redshift and distance, which forms the basis for the modern expansion paradigm.
According to Gamow this led Einstein to declare this cosmological model, and especially
the introduction of the cosmological constant, his "biggest blunder".[1]
Even after Hubble's observations, Fritz Zwicky proposed that a static universe
could still be viable if there was an alternative explanation of redshift due to a mechanism
that would cause light to lose energy as it traveled through space, a concept that would
come to be known as "tired light". However, subsequent cosmological observations have
shown that this model is not a viable alternative either, leading nearly all astrophysicists to
conclude that the static universe is not the correct model of our universe.
Einstein's universe
Einstein's static universe is closed (i.e. has hyperspherical topology and
positive spatial curvature), and contains uniform dust and a positive cosmological
constant with value precisely ΛE = 4πGρ / c2, where G is Newtonian gravitational
constant, ρ is the energy density of the matter in the universe and c is the speed of light.
The radius of curvature of space of the Einstein universe is equal to
The Einstein universe is one of Friedmann's solutions to Einstein's field equation for dust with density ρ,
cosmological constant ΛE, and radius of curvature RE. It is the only non-trivial static solution to Friedmann's
equations[citation needed].
Because the universe is now known to be expanding the Einstein universe is no longer regarded as a
viable model for our universe. Moreover, it is unstable in the sense that any change in either the value of the
cosmological constant, the matter density, or the spatial curvature will result in a universe that either expands and
accelerates forever or re-collapses to a big crunch.[citation needed]
After observations indicated that the universe was expanding, most physicists of the twentieth century
assumed the cosmological constant is zero. If so (absent some other form of dark energy), the expansion of the
universe would be decelerating. However, with the discovery of the accelerating universe, a positive cosmological
constant has been revived as a simple explanation for dark energy.
Other problems with the model
Aside from Hubble's law, the cosmic microwave background radiation is used as empirical evidence of
the Big Bang model. A static universe model has to explain this radiation in some other way. Also there has to be
some process of "recreation of Hydrogen" since if the universe was not created some finite time ago, as in the Big
Bang model, the stars would otherwise all have run out of fuel (Hydrogen) by now.
Oscillating Universe
One of the implications of the big-bang theory is that the universe will one day end, or at
least any life in the universe will come to an end. If the universe is either open or flat, meaning
that it expands forever, it will survive for an infinite period of time. But eventually all the
material in all the generations of stars will be exhausted and the universe will grow cold and
dark. In a closed universe, in which the expansion eventually stops and a contraction follows,
the end is far from cold and dark—as the Big Crunch approaches, the universe grows hotter and
brighter until it implodes into a singularity and gets crushed out of existence.
But is that what would really happen? Some scientists speculate that the Big Crunch would
not signal the end. Perhaps another Big Bang would follow the Big Crunch, giving rise to a new
universe of possibilities. The idea that Bangs follow Crunches in a never-ending cycle is known as
an oscillating universe. Though no theory has been developed to explain how this could ever
happen, it has a certain philosophical appeal to people who like the idea of a universe without
end.
http://www.pbs.org/wnet/hawking/universes/html/osci.html
Fate of the Universe
http://www.universetoday.com/37105/fate-of-the-universe/
by John Carl Villanueva on August 10, 2009
What is the ultimate fate of our universe? A Big Crunch? A Big Freeze? A Big Rip? or a Big Bounce? Measurements
made by WMAP or the Wilkinson Microwave Anisotropy Probe favor a Big Freeze. But until a deeper understanding of dark energy is
established, the other three still cannot be totally ignored.
Ever since scientists proved the Big Bang to be the most plausible cosmological theory, and since it only
focused more on how it might have all began, their attention started to shift to how the Universe would end. Thus, all 4
theories mentioned above (Big Crunch, Big Freeze, etc.) are actually offshoots of the Big Bang.
The Big Crunch predicts that, after having expanded to its maximum size, the Universe will finally collapse
into itself to form the greatest black hole ever.
On the opposite side of the coin, the Big Freeze foretells of a universe that will continue to stretch forever,
distributing heat evenly in the process until none is left to be usable enough. Hence, it is also known as the Heat Death.
A more dramatic version of the Big Freeze is the Big Rip. In this scenario, the Universe’s rate of expansion
will increase substantially so that everything in it, down to the smallest atom, will be ripped apart.
In a cyclic or oscillatory model of the Universe, there will be no end … for matter and energy, that is. But for
us and the Universe that we know of, there will definitely be a conclusion. In an oscillatory model, the Big Bang and Big
Crunch form a pair known as the Big Bounce. Essentially, such a universe would simply expand and contract (or bounce)
forever.
For astronomers to determine what the ultimate fate of the Universe should be, they would need to know
certain information. Its density is supposedly one of the most telling.
You see, if its density is found to be less than the critical density, then only a Big Freeze or a Big Rip would
be possible. On the other hand, if it is greater than the said critical value, then a Big Crunch or Big Bounce would most
likely ensue.
The most accurate measurements on the cosmic microwave background radiation (CMBR), which is also the
most persuasive evidence of the Big Bang, shows a universe having a density virtually equal to the critical density. The
measurements also exhibit the characteristics of a flat universe. Right now, it looks like all gathered data indicate that a
Big Crunch or a Big Bounce is highly unlikely to occur.
To render finality to these findings however, scientists will need to know the exact behavior of dark energy. Is
its strength increasing? Is it diminishing? Is it constant? Only by answering these will they know the ultimate fate of the
Universe.
We’ve got a few articles that touch on the fate the universe here in Universe Today. Here are two of them:
No “Big Rip” in our Future: Chandra Provides Insights Into Dark Energy End of the Universe
NASA also has some more:The Life and Death of Stars
What is the Ultimate Fate of the Universe
i) ROYGBIV. The red end of the visible spectrum is lower energy, while the blue end of the
spectrum is higher energy.
ii) Objects that approach us create higher energy waves, and therefore are seen in a blue
colour. Objects going away from us create lower energy waves, and are seen as red in colour.
a) Redshifting is the effect an object has that is moving away from us.
b) Blueshifting is the effect that an object has that is moving toward us.
c) Hubble discovered that all the stars were redshifting: moving away from us.
d) They also use it to talk about gravitational redshifting, as well as cosmological
redshifting, the idea that all objects in the universe is moving outward from a
single origin.
iii) This brings about the theory of the Big Bang- the theory that all matter in the universe
is moving outward, away from each other.
Scientists now apply the concept of the Doppler Effect for measuring all the other bands of
the electromagnetic spectrum- radio, microwave, infrared, ultraviolet, X-ray, and gamma
rays.
KuiperBelt
= a disc-shaped region of icy objects beyond the orbit of Neptune
billions of kilometers from our sun.
a) Pluto and Eris are the best known
b) There may be hundreds more of these ice dwarfs.
c) The Kuiper Belt and even more distant Oort Cloud are believed to
be the home of comets that orbit our sun.
The discovery of Eris -- which is similar in size to Pluto -- caused
scientists to reconsider the definition of a planet. It has a moon
named Dysnomia.
•NASA's New Horizons will be the first spacecraft to visit Pluto and
the Kuiper Belt. The spacecraft's journey began in January 2006. It
will continue into the Kuiper Belt after its Pluto flyby in 2015.
Eris Discovery Images
Oort Cloud
= a cloud of icy bodies beyond our solar
system.
a) contains 0.1 to 2 trillion icy bodies in
solar orbit
b) comets are some of these icy
particles that were bounced out of its
regular orbit and fall into the inner
solar system.
i) Long period comets are large,
strange orbits that take
thousands of years to orbit.
ii) Short period comets take less
than 200 years to orbit the sun.
Oort Cloud
Sedna's Orbit
1
2
These four panels
show the location of
the newly discovered
planet-like object,
dubbed "Sedna,"
which lies in the
farthest reaches of
our Solar System.
3
4
Each panel, moving
counterclockwise
from the upper left,
successively zooms
out to place Sedna in
context.
1
The first panel shows the orbits of the inner
planets, including Earth, and the asteroid
belt that lies between Mars and Jupiter.
2
In this second panel, Sedna is shown well
outside the orbits of the outer planets and
the more distant Kuiper Belt objects.
The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the
Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than
scientists believed.
Image Credit: NASA/JPL-Caltech/R. Hurt (SSC-Caltech)
Credit: NASA/Caltech
3
Sedna's full orbit is illustrated in the third
panel along with the object's current
location. Sedna is nearing its closest
approach to the Sun; its 10,000-year orbit
typically takes it to far greater distances.
4
The final panel zooms out much farther,
showing that even this large elliptical orbit
falls inside what was previously thought to be
the inner edge of the Oort cloud.
How the Kuiper Belt and Oort Cloud Got Their Names
Both distant regions are named for the astronomers who predicted their existence -- Gerard Kuiper and Jan Oort.
Objects discovered in the Kuiper Belt get their names
from diverse mythologies:
Eris, the Greek goddess of discord, is often credited
Artist's impression of Eris
and her moon Dysnomia by
Thierry Lombry
Eris is named for the
Greek goddess of discord
and strife.
Comets
from both
regions are
generally
named for
the person
who
discovered
them
.
with starting the Trojan War. Alone among the
Olympians, she was excluded from the arranged
marriage of Peleus and Thetis because of her
troublemaking inclinations. But exclusion was no
deterrent. She tossed the Apple of Discord into the
party, a golden apple inscribed καλλίστῃ (kallistei) – "to
the fairest" – provoking Hera, Athena and Aphrodite to
begin quarreling about the appropriate recipient. Paris,
Prince of Troy, was appointed judge. Each of the three
goddesses immediately attempted to bribe him. Hera
offered political power; Athena promised skill in battle;
and Aphrodite tempted him with the most beautiful
woman in the world: Helen, wife of Menelaus of Sparta.
While Greek culture placed a greater emphasis on
prowess and power (Athena and Hera's domain), Paris
chose to award the apple to Aphrodite (= Venus),
thereby dooming his city, which was destroyed in the
war that ensued when the Spartans demanded the
return of their queen.
Haumea is named for a Hawaiian goddess
of fertility and childbirth.
Haumea sits among the trans-Neptunian objects, a vast
ring of distant cold and rocky bodies in the outer Solar System. At this
moment it is roughly 50 times the Sun-Earth distance from the Sun,
but at its closest the elliptical orbit of Haumea brings it 35 times the
Sun-Earth distance from our star.
Haumea is the name of the goddess of childbirth and
fertility in Hawaiian mythology. The name is particularly apt as the
goddess Haumea also represents the element of stone and
observations of Haumea hint that, unusually, the dwarf planet is
almost entirely composed of rock with a crust of pure ice.
Hawaiian mythology says that the goddess Haumea's
children sprang from different parts of her body. The dwarf planet
Haumea has a similar history, as it is joined in its orbit by two
satellites that are thought to have been created by impacts with it in
the past. During these impacts, parts of Haumea's icy surface were
blasted off. The debris from these impacts is then thought to have
gone onto form the two moons.
Significant Dates
1943: Astronomer Kenneth Edgeworth suggests that a reservoir of comets and larger bodies resides beyond
the planets.
1950: Astronomer Jan Oort theorizes that a vast population of comets may exist in a huge cloud on the
distant edges of our solar system.
1951: Astronomer Gerard Kuiper predicts the existence of a belt of icy objects just beyond the orbit of
Neptune.
1992: After five years of searching, astronomers David Jewitt and Jane Luu discover the first KBO, 1992QB1.
2002: Scientists using the 48-inch Oschin telescope at Palomar Observatory find Quaoar, the first large KBO
hundreds of kilometers in diameter. This object was photographed in 1980, but was not noticed in those
images.
2004: Astronomers using the 48-inch Oschin telescope announce the discovery of Sedna (2003VB12).
2005: Astronomers announce the discovery of 2003UB313. This object, later named Eris, is slightly larger
than Pluto.
2008: The Kuiper Belt object provisionally known as 2005FY9 ("Easterbunny") is recognized in July as a dwarf
planet and named Makemake (pronounced MAHkeh-MAHkeh) after the Polynesian (Rapa Nui) creation god.
In September, 2003EL61 ("Santa") was designated a dwarf planet and given the name Haumea after the
Hawaiian goddess of fertility and childbirth.
q discuss the variation in day length over a year for different latitudes
Day Length
= the time when the sun appears above the horizon, from
sunrise to sunset
There is still daylight after sunset. This period of time is
called twilight.
Length of a day depends on an area’s latitude
(= the distance from the equator) and the tilt of the
earth’s axis.
The rotation of the earth, along with the latitudes,
causes some interesting things:
a) At a given latitude, the duration of the longest day in the
northern hemisphere (on or about June 21) is the same as the
duration of the longest day in the southern hemisphere (on or
about December 21);
b) Also, the duration of the shortest day in the northern hemisphere
(on or about December 21) is the same as the duration of the
shortest day in the southern hemisphere (on or about June 21);
c) The Arctic Circle is the southernmost latitude where 24-hour
daylight can occur at least on one day of a year (northern
summer solstice on or about June 21);
d) The Antarctic Circle is the northernmost latitude where 24-hour
daylight can occur at least on one day of a year (southern
summer solstice on or about December 21).
(Above) Pictures of the sun taken 1 hour apart. This and the following images were
from a scientific expedition in Antarctica, at a base located approximately 75o South.
(Above)Although DdU is a little south of the Antarctic circle, the sun is always visible at noon, even at the darkest of the winter. The reason is
because of the refraction of light on the low atmosphere layers: you can actually see it while it's somewhat below the horizon. This picture was
taken on June 21st with 9 exposures set 11 minutes apart if I remember right. One hour of sunlight is all we get in winter. Enough to go for a walk,
but little else. I created my animated HR bar starting from this picture.
•Each pole has only one sunrise and one sunset per year, around the time of the equinoxes. Each pole’s
sunrise is nearly coincidental with the other’s sunset.
Evidence That Shows The Earth Rotates About Its Axis And Revolves
Around The Sun
1) Foucault’s Pendulum
a) 1851- Foucault suspended a 60-m pendulum
weighing about 25kg from the domed ceiling
of the Pantheon in Paris.
b) He started the pendulum swinging evenly by
drawing it to one side with a cord and then
burning the cord to start the pendulum
swinging.
c) The direction of swing of the pendulum was
recorded on a ring of sand placed on a table
beneath its point of suspension.
d) At the end of each swing a pointed stylus
attached to the bottom of the bob cut a notch
in the sand.
e) After a few moments it became apparent
that the plane of oscillation (swing) of the
pendulum was slowly changing with respect
to the ring of sand, and hence with respect
to the Earth.
Foucault’s Pendulum in the Pantheon in Paris
The pendulum bob (above) weighed 28 kg and was brass-coated lead. It was
suspended from a wire 67 meters long! This replica in the Pantheon in Paris has
been permanently swinging since 1995.
These drawings show the pattern that emerged when the
pendulum was set in motion.
(left) The blue arcs show the pendulum swing; the green
lines show the pattern left in the sand. Each pass was 11°
different from the previous pass.
http://www.youtube.com/watch?
v=6oYvffE6iGY&feature=related
2) The Earth isn't round. It bulges around the equator, just as you would expect if it rotated. This
was known when Foucault made his pendulum.
3) Coriolis Effect
1)Because each and every part of the Earth
rotates full circle in 24 hours, different parts of
the face of the Earth are actually moving through
space at different speeds.
2)A point on the equator of the Earth moves
about 24,000 miles in 24 hours, or about 1000
miles per hour.
3)On the other hand, a piece of ground 4 feet
from the North Pole moves only 24 feet in 24
hours, for a slow speed of 1 foot per hour!
FUNKY NOTE:
The Coriolis Effect was largely a curiosity until World War I,
when the Germans built a generation of long-range cannons and
found that they could not hit anything if they aimed directly
at it; they had to aim to the left. (If the target was exactly
east or west of the gun's position, the gun would be aimed
directly at it.)
If you understand this discussion, you should be able to
convince yourself that a cannonball fired southward (toward
the equator) from some point in the Northern Hemisphere will
be deflected to its right (west).
Effects such as these that come about because we live on a
rotating frame of reference are referred to as Coriolis
effects.
The Motion Of Stars And Planets Are Caused By Rotation And Revolution Of The Earth
1) The earth’s axis is in line with one Northern Hemisphere star:
Polaris.
2) Polaris is part of the Little Dipper (Ursa Minor)
3) It is found by drawing a line from the outer lip of the Big Dipper
(part of Ursa Major).
4) Polaris is located 10 off to the side of the north celestial pole, so
it makes a very small arc as the earth rotates
5) All stars and planets rotate around Polaris
Polaris
Left: Star rotation shown by a
long exposure. The star in the
middle is Polaris.
http://www.nakedeyeplanets.com
Above: A shooting star and a passing satellite
caught by a long exposure photography.