Name: _
Answer key__
Pretest: _
2_/ 58
58_/ 58
Pretest Ch 20: Origins of the Universe
Posttest: _
Vocab/Matching: Match the definition on the left with the term on the right by
placing the letter of the term on the blank.
P__ the Doppler effect applied to light, shows
1. __
galaxies are moving away from us
A. Albert Einstein
B. Big Bang
mass and will continue expanding forever
C. Closed universe
D. Cosmic microwave
the Big Bang Theory
background radiation
E. Dark matter
energy
F. Edwin Hubble
G. Fred Hoyle
was condensed into
H. Fundamental forces
I. Georges Lemaitre
molecular forces
J. Hypothesis
K. Law
of experimental evidence, may change
over time
M. Open universe
N. Oscillating universe
O. Penzias & Wilson
M__ where the universe has a low amount of
2. __
O__ discovered CMBR in the 1960s and proved
3. __
S__ everything that exists; all the matter and
4. __
Q__ the small point that everything that exists
5. __
H__ gravity, electromagnetism, strong and weak
6. __
J__ a scientific guess, based on a small amount
7. __
F__ used red shift to discover the universe is
8. __
expanding, in 1920’s
B__ theory that all that exists now was once in
9. __
one small point and started expanding
P. Red shift
Q. Singularity
R. Theory
S. Universe
E__ we can not see it, but can measure its
10. __
effects; black holes are an example
R__ an explanation for a natural phenomenon, has much evidence to back it
11. __
up, tends to be complex
A__ had the idea that the universe must not be static (unchanging) but had no
12. __
evidence
D__ microwave energy left over from the “Big Bang” event that we can still
13. __
measure today
N__ this is just one Big Bang in a series of Big Bangs/Big Crunches/Big
14. __
Bangs/Big Crunches
G__ gave the Big Bang Theory its name while
15. __
trying to make fun of it
I
16. __ __ started the Big Bang theory, though he had no evidence to support it
K__ a simple statement that describes “what” happens in natural phenomenon
17. __
C__ the amount of matter in the universe is finite (set); the universe will
18. __
collapse back in on itself or stay one size forever.
If the following statement applies to a hypothesis, put a letter H. If it applies to a scientific
theory, put the letter T. If it applies to a scientific law, put the letter L. It is possible to
have more than one letter or no letters at all on a blank.
19. __
H___ an educated guess about a phenomenon
20. __
H___ can become a law
21. __
H T L__ can be changed
22. __
L____ describes a phenomenon (answers “what”)
23. _______ is more important than a theory
24. ___
L___ tends to be simple, often just a mathematical equation
T L__ has a lot of evidence to back it up
25. _
26. __
T___ explains a phenomenon (answers “why” or “how”)
T L__ is considered to be “true” or a “fact” by the scientific community
27. _
28. ___
H___ can become a theory
29. ___
H___ may not have evidence to back it up
H T L__ can be proven false with further evidence/experimentation/observation
30. _
31. __
T___ tends to be very detailed and complex
H T L_ can be used to make predictions
32. _
33. The following list identifies some of the “events” that have taken place according to Big
Bang Theory. Put this list in a proper sequential order in time…
A. Formation of atoms (nuclei + electrons)
B. The 4 fundamental forces of nature become distinguishable
C. Supernova create conditions for the nuclear production of elements heavier
than iron
D. The first particles form from energy
E. Something, not yet understood, causes the early universe (all of space and
energy) to begin a process of rapid expansion from a singularity
F. The first stars form initiating the nuclear fusion process to create the
elements up through iron.
G. Formation of galaxies
H. Formation of simple atomic nuclei (combinations of protons and neutrons)
E__  __B__  __D__  __H__  __A__  __G___  __F__  __C__
__
34. What needed to happen in the universe before it was possible for the first atoms to form?
Cool down so energy could become matter
(quarks…eventually form atomic nuclei
(protons & neutrons) then atoms)
35. What is so special about the time 10-43 seconds after the initial “bang”?
.0000000000000000000000000000000000
00000001 sec
We don’t know what happened before that.
The models we use rely on 4 “fundamental
forces” of physics….gravity, electromagnetism,
weak molecular force, strong molecular force.
Those forces had not existed before then…they
were all one “superforce” so we can’t use
science to explain what was happening, because
science (as we know it) wasn’t “working” then.
36. According to Big Bang Theory what significant event occurred approximately 300,000
years after the initial “bang”?
first atoms were made (H & He)…cooled
down enough (about 3000 K).
That cleared up the “soup” and allowed light
to shine through. We detect this now as CMBR.
37. A very common misconception about the Big Bang is that people tend to view it as some
giant explosion. Scientist wouldn’t describe it this way. What would be a more
appropriate description for what occurred at the very beginning according to Big Bang
Theory?
Rapid expansion…from size of atom to 8x
solar system in less than a second.
The list on the left contains a few significant pieces of evidence that support some aspect of
Big Bang Theory. For each item listed, describe the way in which it supports Big Bang
Theory, briefly describe how this information is known, and identify the scientist(s)
associated with the evidence.
Evidence
The
universe is
expanding
How it supports BBT
Scientist(s)
38. if expanding 39.
now, was once
Hubble,
small in the past 1929
How is this known
40. Red shift.
Light from
galaxies is
shifted towards
red end of
spectrum
means its
moving away
from us
(Doppler Effect
for light)
Einstein, Theory of
1916
general
Relativity says
that objects
with gravity
have to be
moving, so
universe can’t
just stay the
same
Lemaitre, Based on
1927
Einstein,
predicted it
would expand,
couldn’t prove,
people ignored
him
Cosmic
Microwave
Background
Radiation
41. The energy
left over from
the formation of
the universe.
Over time, it has
shifted towards
microwave end
of spectrum.
This light
existed in early
universe, but
was blocked by
all the
unorganized
matter. By
300,000 years
after the Event,
the universe had
cooled down
enough for the
light to be seen.
42.
Penzias
& Wilson,
1964
43. BBT
predicts there
would be some
residual energy
left over that’s
(was
not coming
predicted from 1 place in
by others space, but has
before
expanded (as
that, but the universe
they
did) to come
actually
from all over.
found it) That’s what
CMBR
does…comes
from
everywhere.
Abundance
of light
elements
(hydrogen
and helium)
in the
universe
44. The
conditions in the
early universe
would only make
the simplest of
elements …
Hydrogen and
Helium. Thus we
should find a lot
of hydrogen and
helium in the
universe today.
There have
been many
contributors
to identifying
composition
45. 74% of the
universe is
Hydrogen and
25% is Helium.
Other heavier
elements came
from stars
processes
(fusion) and
supernovas (star
explosions) as
predicted by
Hoyle.
46. Measurements of the “red shift” of light from distant galaxies informs scientists that the
universe is expanding. What is “red shift”? Why does this show something is moving
away from us?
Red shift…Doppler Effect applied to light.
As objects move away from us, their
wavelengths are stretched out (become longer)
this shifts it towards the red end of the
spectrum. The more it shifts the faster it is
moving.
If things move towards us, the wavelengths
are compressed (shortened) and shifted towards
the blue end of the spectrum.
Given the notion that the universe is currently expanding as described by Big Bang
Theory, there are, in general, three possible outcomes for the future. Identify/describe
those three possibilities for the “fate” of the universe:
47. Keep expanding forever (open universe, Big
Rip)
48. Expand to a certain point and stop (flat
universe, Big Freeze)
49. Expand to a certain point and contract
again (closed universe, Big
Crunch/Oscillating Universe)
50. What will determine which of the above scenarios actually happens?
The amount of mass in the universe. The
problem is that there is a lot of matter we can’t
see, but know it’s there because of its
gravitational effects (dark matter). So it’s hard
to measure the amount of mass.
Describe how #50 will do this for each of #47 - #49 above.
If the amount of mass is over a certain limit,
the universe will collapse back in on itself
(closed universe/Big Crunch)
51.
If the amount of mass is “just right” the
universe will grow to a certain size and stay
there (Flat universe/Big Freeze)
52.
If the amount of mass is under the certain
limit, it will just keep expanding forever (open
universe, Big Rip)
53.
54. Which of the three outcomes identified in 47 - 49 seems to be supported by current
data?
Universe expanding forever (open
universe/Big Rip) … there appears to be too low
of an amount of mass for the gravity to stop the
expansion or to stop it and bring everything
back together.
Hubble found that galaxies are speeding up
the farther away they are, the faster they move
(speeding up, not slowing down)
55. What is a galaxy and what is ours called?
Collection of billions of stars. Ours is called
the Milky Way and is estimated to contain
between 200,000,000,000 and 400,000,000,000
stars. It is 100,000 ly across (light takes
100,000 years to cross it!)
56. – 58. There are three shapes to galaxies. Name and draw them. What kind is ours?
Elliptical
Spirals (2 kinds spiral or barred spiral)
Irregular…gravity of nearby objects gives it odd
shape