Answer Key: Big Bang Balloon Analysis Questions
1. As the balloon was inflated, the distances between the home dot and each of the other five
dots increased. HERE IS WHERE YOU NEED TO CITE ACTUAL DATA! You should give several
examples using the actual numbers from your data and explaining what they mean.
2. The dots farthest from the home dot appeared to move greater distances away from the home
dot than the dots nearer to the home dot. ONCE AGAIN: CITE ACTUAL DATA! You should give
several examples using the actual numbers from your data and explaining what they mean. (note: One
group said they had a dot with opposite results. This could be due to the not-quite-round shape of the
balloon or human error.)
3. Since they moved a greater distance in the same amount of time, the farther dots must have been moving
faster than the closer dots. ONCE AGAIN: CITE ACTUAL DATA! You should give several examples
using the actual numbers from your data and explaining what they mean.
4. When Hubble observed the redshift of the light coming from stars and galaxies, he realized that the
galaxies were moving away from each other. He also determined that the farther a galaxy is from us, the
faster it is moving. The galaxies in the universe behave like the dots on the expanding balloon. The
distance from each dot to the Home dot increased every time the balloon expanded. Hubble concluded
that the universe is expanding, just like our balloon expanded.
5. One idea for a model (the “classic”!): Rising bread dough with raisins in it!
Whatever model you came up with, you should have explained how it makes a good model. For
example, the raisins in the bread dough would represent the galaxies. As the bread dough rises, each
raisin moves away from all the other raisins. Unlike the balloon, there are raisins scattered all the way
throughout the dough instead of only on the surface. This makes the bread dough more 3-Dimensional
and therefore a better model of the universe than the balloon. (See your textbook for the rest of that
explanation.)
We didn’t have to write a conclusion, but here is a sample one for your edification:
Sample conclusion section for Big Bang Balloon Lab
This experiment modeled the expansion of the universe. As the balloon was inflated, the dots moved
farther away from the home dot and each other. The results show that the farther away a dot is from the
home dot, the faster its movement. In the 1920’s, astronomer Edwin Hubble observed that the galaxies
are moving in the same way. Hubble concluded that the Universe must be expanding, like our balloon
did. This conclusion later led to the Big Bang Theory of the Origin of the Universe.
If you want to read more about the Universe read on……..
Notes on The Universe
What is the Universe?
The universe is everything – planets, stars, galaxies, space, and even time! No one knows
how big the universe is. In the past, many people thought the universe was infinite. Now,
most cosmologists (astronomers who study the universe. “Kosmos” is a Greek word that
means “the organization of everything.”) agree that the universe is finite, meaning it does
have an end and does not go on forever. However, that might be even more difficult to
imagine than an infinite universe!
The Origin of the Universe
Way back in 1929, astronomer Edwin Hubble observed (through a ginormous telescope and
associated equipment through which he actually observed the redshift of the galaxies, and
knowing about the Doppler Effect, inferred..) that galaxies are moving away from each other.
Because of this observation, he concluded that the universe must be expanding. (Here is the
tricky part: it’s not expanding “into” anything because there is no space outside the universe
and the universe has no outer edge. Space is expanding right along with all the matter it
contains. Don’t worry if that bit boggles your mind. Even cosmologists don’t fully
understand the nature of the universe. But they don’t give up! Perhaps some day you will be
one of the people who unlock the secrets of our mysterious universe…!)
The Big Bang
Since the universe is expanding, at some point in the past, it must have been smaller. It would
have been so small that all the matter it contains would have been condensed (smashed
together) in a single, very dense point. This point, called a singularity, contained all the
matter in the universe – although it really wasn’t matter YET. It would have been superduper hot (more than a trillion degrees!) and super-duper condensed (squished). Sometime
between 12 and 18 billion years ago, we think around 14 billion, this point exploded –
although not like an explosion in an action movie. There really isn’t an ideal word to describe
this sudden expansion outward. So when we say “Big Bang,” we are being somewhat
metaphorical. That’s why we call this theory of the universe’s origin the Big Bang Theory
(not because our balloons made a big bang when we popped them!). The “Big Bang” marks
the beginning of space and time.
Evidence Supporting the Big Bang Theory
Remember, science knowledge is built on data and evidence. The Big Bang Theory is the
theory accepted by most scientists because there is such a large amount of evidence
supporting it.
1. Redshift: You already know about this first bit of evidence! As Edwin Hubble first
observed, the stars and galaxies are redshifted. This indicates that they are all moving
away from us and from each other. The farther away a galaxy is, the faster it is
moving. This shows the Universe is expanding.
2. Cosmic Microwave Background Radiation (aka CMB): Okay, this is really cool!
Remember, the infant Universe would have been a very, very hot place. As it
expanded, it would have cooled down. Way back in the 1940’s, astronomers realized
that the heat from the baby Universe would still exist in the form of a large amount of
radiation in the “background” of the universe – “leftover” energy from the initial
expansion. These astronomers predicted that this “cosmic background radiation,” as
they termed it, would eventually be found. In 1965, some astronomers at Princeton
were devising an experiment to look for this predicted, but before they could carry it
out, this radiation was actually found by accident! Right here in New Jersey, a couple
of engineers were using a microwave antenna in order to try to detect emissions from
gas in the Milky Way Galaxy. They encountered a lot of excess “noise” – kind of like
static when you are trying to tune in a radio station and aren’t getting good reception.
At first they thought this was a malfunction in the equipment – or maybe it was being
caused by bird droppings on the receiver! It turned out they had found the cosmic
background radiation! The CMB is very, very cold and so is therefore mostly in the
form of microwaves/radio waves (remember, these waves are all part of the
electromagnetic spectrum. Microwaves have a frequency between 0.3 GHz to 300
GHz, and radio waves have a frequency between 3 Hz to 300 GHz. So microwaves
are really a type of radio wave.). We can’t see microwaves of course, but we can
detect them. The CMB fills the universe and can be detected everywhere we look!
This is very strong evidence supporting the Big Bang Theory that can’t be explained
in any other way.
How did the universe go from one tiny, super-hot, super-dense speck to stars, planets,
galaxies, etc.?
As the universe expanded, it cooled. Familiar kinds of matter, such as protons, electrons, and
neutrons began to appear. As time continued, these atomic particles merged to make the
simplest chemical elements, hydrogen and helium. The earliest stars and galaxies were
formed from these simple elements. Once stars formed, their intense nuclear reactions began
creating more complex elements, such as oxygen, carbon, lead, and gold. The earliest
massive stars exploded into supernovas in which heavier elements were forged, These
complex elements formed other stars, including our own sun, all the planets and other objects
in our solar system, and, yes, even us! As a matter of fact, you and I and all the other things
on Earth, both living and non-living, are made of recycled stars. How cool is that?
How old is the Universe?
How do we know the universe is 12 – 15 billion years old? Astronomers can measure the
distances between galaxies and how fast they are moving apart. With that information, they
can estimate the age of the universe.
The Shape of the Universe
The shape of the universe is a mystery. Some cosmologists theorize that it has a curved
shape. If the universe is curved, that means that if you traveled in a straight line long enough,
you would end up back where you started! But don’t worry! No one could travel that far!
And here’s something that is hard to understand: There is no CENTER of the Universe. In
other words, you wouldn’t be able to point to one particular spot and say, “This is the middle.
This is where it all started.” Remember, there wasn’t any actual explosion, like for example a
bomb or a firecracker. The ENTIRE universe is expanding equally in all places. (Yeah, my
brain is a bit boggled – is yours?)
Will the Universe ever end?
So, the Big Bang was the beginning of a universe that is expanding along with space itself.
Will this expansion continue forever? Astronomers used to think that eventually gravity
would pull the universe back together and it would shrink until everything in it would come
together in a “Big Crunch.” Now most astronomers think the universe will either continue to
expand forever or else it will slow down and stabilize.
Other Theories:
As I said earlier, the Big Bang is the theory that is currently accepted by most astronomers
because we have so much supporting evidence. But remember, science is dynamic! We are
always having new ideas and learning new things and finding new evidence. Our understandings
of scientific concepts evolve along with our knowledge. If new evidence is found to support a
different theory, the Big Bang will be discarded, or perhaps simply modified.