CHAPTER 1.3
BIRTH OF A THEORY: THE BIG BANG!
THEORY & LAW
1) Theory
a) A hypothesis or a set of hypotheses that is supported by
the results of experimentation and observation.
b)Provides a general explanation for scientific
observations.
2) Scientific Law
a) A rule that correctly describes a natural phenomenon.
b)A theory must be proven true every time it is tested to
become a law.
SPECTRUM
1)Spectrum
a)Isaac Newton discovered that
sunlight passing through a glass
prism produces a band of color.
b)These colors are red, orange,
yellow, green, blue, and violet.
SPECTRUM
WAVELENGTH
1)Wavelength
a)The distance from the crest of one
wave to the crest of the next wave.
b)Each color in the spectrum has a
unique wavelength.
c)The wavelengths decrease in length
from red to violet.
WAVELENGTH
BRIGHT LINE SPECTRUM
1) Bright-Light Spectrum
a)Each element on the periodic table of elements,
when heated, will produce its own spectrum of
colors.
b)Since these elements only produce a series of
thin colored lines spaced at uneven intervals we
know they produce specific wavelengths and the
spectrum is unique to the element.
BRIGHT LINE SPECTRUM
DOPPLER EFFECT
1) Doppler Effect (www.scilinks.org Code:MES018)
a) The apparent shift in the wavelengths of energy emitted
by an energy source moving away from or toward an
observer.
b)When light, or energy, is moving toward a person the
wavelengths of the light appear to become shorter, or
moving toward the blue end of the spectrum.
c) When light, or energy, is moving away from a person
the wavelengths of the light appear to become longer, or
moving toward the red end of the spectrum.
d)The faster the energy source is moving the faster the
wavelength the shift appears to be.
LIGHT & DOPPLER EFFECT
DOPPLER EFFECT
• http://www.upscale.utoronto.ca/GeneralInterest/H
arrison/Flash/ClassMechanics/DopplerWaveFronts/
DopplerWaveFronts.html
• http://faraday.physics.utoronto.ca/PVB/Harrison/Fla
sh/ClassMechanics/Doppler/DopplerEffect.html
RED SHIFT
1) Red Shift
a) Spectroscope
i) A device that contains a prism which splits light into a
spectrum of different colors and wavelengths.
ii)Scientists used a spectroscope to view the spectrum of
various stars, and by comparing the spectrum to known
elements they are able to determine what elements are in
each star.
b) Observing the spectrum of stars, scientists noticed that most
galaxies are shifted toward the red end of the spectrum.
Which indicates they are moving away from Earth.
i) These observations indicate that the universe is
expanding.
RED SHIFT
BIG BANG THEORY
1) Big Bang Theory
a)Scientists believe that billions of years ago all of the
matter and energy was compressed into an
extremely small volume.
b)Approximately 15 billion years ago, scientists
believe, all the matter and energy began expanding
outward in a giant cloud form.
c)This giant cloud eventually began forming clumps
of matter and energy which we now know as
galaxies.
BIG BANG THEORY
a)This outward movement of matter is still occurring
today. Which is why we see the red shift in galaxies.
b)This theory was greatly doubted by the scientific
world until researches detected low levels of energy
evenly distributed throughout the universe called
background radiation.
c)This theory is still a theory, cannot be proven to
law, and must continue to be tested until proved or
disproved.
BIG BANG THEORY