Geology

FORMATION OF THE EARTH

The Doppler Effect: Sound waves compress or relax with relative motion.

Compressed: shorter wavelength; higher frequency.

Relaxed: longer wavelength; lower frequency.

The Doppler Effect influences light waves, too.

Visible wavelengths range from 400 and 700 nanometers.

400 nm—blue = higher frequency.

700 nm—red = lower frequency.

Moving light waves reveal the Doppler effect.

Light moving toward an observer compresses (blue).

Light moving away from an observer expands (red).

The Red Shift: A moving star displays Doppler shifted light

Approaching starlight is compressed (blue-shifted).

Receding starlight is expanded (red-shifted).

Expanding Universe: Light from galaxies, observed to be “red-shifted.”

- Edwin Hubble recognized the red shift as a Doppler effect. Concluded galaxies were moving away at great speed and no galaxies were found heading toward Earth. Also, deduced that the whole Universe must be expanding (analogous to raisin bread dough).

- The expanding Universe theory.

Forming the universe: Vastness of the universe is staggering.

Earth is a planet orbiting a star on the arm of a galaxy.

Where did all this “stuff” come from?

Big Bang and the Aftermath: All mass and energy in a single point. Exploded – 13.7 Ga and has continued to expand ever since.

Aftermath: Researchers have developed a model of the Big Bang.

- During the first instant, only energy—no matter—present.

- Started as a rapid cascade of events.

Hydrogen atoms within a few seconds.

At 3 minutes, hydrogen atoms fused to form helium atoms.

Light nuclei (Be, Li, B) by Big Bang nucleosynthesis.

The Universe expanded and cooled.

With the expansion and cooling, atoms began to bond

Mass in nebulae was not equally distributed.

An initially more massive region began to pull in gas.

This region gained mass and...