Chapter 10 Chapter 10

Exploring the Exploring the

Universe Universe

10.1 Explaining the Universe Astronomer Edwin HubbleAstronomer Edwin Hubble discovered that all discovered that all galaxiesgalaxies in in

space are space are moving awaymoving away from each other. from each other.

According to the According to the Big Bang TheoryBig Bang Theory,, the universe is believed the universe is believed to have begun during an unimaginably rapid expansion of to have begun during an unimaginably rapid expansion of a tiny volume of space, about a tiny volume of space, about 13.7 billion years ago13.7 billion years ago.. All All the matter in the universe is thought to have been created the matter in the universe is thought to have been created at that moment. at that moment.

• Early Early astronomersastronomers were able to observe outer space were able to observe outer space by using the best instruments of the time, early by using the best instruments of the time, early telescopes. telescopes.

• With the development of more powerful telescopes With the development of more powerful telescopes in the 1920’s, suddenly more in the 1920’s, suddenly more celestial bodies celestial bodies were were discovered. discovered.

• Celestial bodies is a general term for all the objects in Celestial bodies is a general term for all the objects in the sky, including the the sky, including the sunsun, , moonsmoons, , planetsplanets, and , and starsstars..

Astronomer Edwin Hubble an American astronomer was the first one to identify other galaxies besides the Milky Way. He estimated the distance from earth to 46 different galaxies.

Hubble’s ProposalHubble’s ProposalHubble proposed that the universe is Hubble proposed that the universe is expanding.expanding. The The galaxies which are further away from Earth are movinggalaxies which are further away from Earth are movingapart apart fasterfaster than those closer to Earth. He used the than those closer to Earth. He used theanalogy comparing an uncooked loaf of raisin bread toanalogy comparing an uncooked loaf of raisin bread toone that is put into the oven. As the dough rises theone that is put into the oven. As the dough rises theraisins (galaxies) are moving further away from eachraisins (galaxies) are moving further away from eachother. other.

Red Shift Analysis Red Shift Analysis Edwin Hubble figured out that galaxiesgalaxies were

moving away from the earth at a certain speed, which was proportional to the distance from earth. He did this based on his understanding of the electromagnetic electromagnetic spectrum. spectrum.

ELECTROMAGNETIC WAVESELECTROMAGNETIC WAVES Visible lightVisible light is only one form of energy that reaches

the earth from distant stars (sun). Many other forms of energy with various wavelengths can be measured. These range from long radio waves long radio waves to the shortest waves shortest waves which are gamma rays.gamma rays.

SPECTRAL PATTERNSSPECTRAL PATTERNS White lightWhite light splits into the different lengths of colour

when passed through a prismprism. This is called the visible spectrumvisible spectrum. Light from distant stars can be collected and divided into individual spectral patterns. A spectroscopespectroscope will show the spectral pattern in a starstar in a certain galaxygalaxy..

COSMOLOGICAL RED SHIFTCOSMOLOGICAL RED SHIFT • Edwin Hubble noticed that the light of the galaxies he

was studying showed spectral lines that were shifted toward the red end.

• This red shift red shift occurs because of the light’s wavelengths becoming longer.

• This is an indication the galaxies are moving away from us.

• AstronomersAstronomers call this the cosmological red shiftcosmological red shift, which is evidence for the theory explaining the early universe.

Cosmological Red Shift A red shift means the wavelength is A red shift means the wavelength is

getting longer, and the star is moving getting longer, and the star is moving away from us.away from us.

Blue shift is the opposite; the star is Blue shift is the opposite; the star is getting closer.getting closer.

BIG BANG THEORYBIG BANG THEORY Today the most widely supported theory is that Today the most widely supported theory is that

approximately approximately 13.7 billion 13.7 billion years ago years ago an unimaginably tiny an unimaginably tiny volume of space suddenly and rapidly expanded to immense volume of space suddenly and rapidly expanded to immense size. size.

In that time all the matter and energy in the universe was In that time all the matter and energy in the universe was formed. This is known as the formed. This is known as the Big Bang TheoryBig Bang Theory. .

Cosmic Background RadiationCosmic Background Radiation In In 1963 1963 two astronomers two astronomers Lemaitre Lemaitre and and WilsonWilson were were

monitoring microwave radiation in space. To their monitoring microwave radiation in space. To their surprise they kept receiving background surprise they kept receiving background “noise”“noise” or or signal interference. Their conclusion was they were signal interference. Their conclusion was they were actually detecting actually detecting “cosmic” radiation“cosmic” radiation. They believe . They believe this was radiation this was radiation left overleft over from the Big Bang from the Big Bang expansion. expansion.

Additional Supporting EvidenceAdditional Supporting Evidence Strongest evidence to date comes from the Strongest evidence to date comes from the COBECOBE

Cosmic Background Explorer.Cosmic Background Explorer. The left over radiation The left over radiation from the earth’s expansion due to the Big Bang from the earth’s expansion due to the Big Bang forms forms redsreds and and bluesblues indicating the age since the indicating the age since the expansion took place. The reds indicate hotter expansion took place. The reds indicate hotter temperatures and the blues represent cooler temperatures and the blues represent cooler temperatures which indicates the temperatures which indicates the ageage since since expansion. expansion.

Trying to Simulate THE Trying to Simulate THE BIG BANG THEORYBIG BANG THEORY• What is a What is a ““quarkquark?”?” • Quarks are thought to be smaller Quarks are thought to be smaller subatomic particlessubatomic particles that that

make up make up protonsprotons and and neutrons.neutrons. • Scientists are trying to learn more about these sub atomic Scientists are trying to learn more about these sub atomic

particles by attempting to smash them in a sophisticated particles by attempting to smash them in a sophisticated particle accelerator.particle accelerator.

• By firing protons at each other they are attempting to smash By firing protons at each other they are attempting to smash apart these particles. apart these particles.

• Scientists believe that studying these particles will help them Scientists believe that studying these particles will help them understand how protons and neutrons were understand how protons and neutrons were first created.first created.. .

Section 10.1 Quiz