4.1 - The Big Bang Theory Flashcards
What is the universe defined as, and what does it contain?
The universe is defined as ‘everything that exists.’ It contains planets, comets and asteroids, stars, black holes, and galaxies.
What is a nebula?
An enormous swirling cloud of dust and gas found in galaxies throughout the universe.
Which galaxies are moving the fastest away from us?
The ones that are furthest away.
What does the Big Bang Theory state?
The Big Bang Theory states that about 13.8 billion years ago all matter in the universe was concentrated into a single incredibly tiny point. From this tiny point, the whole universe expanded outwards, and is still expanding, to what it is today.
What are the 2 evidences for the Big Bang Theory?
Cosmic Microwave Background Radiation (CMBR) and Redshift.
What is the history behind CMBR?
In the 1960s, Arno Penzias and Robert Wilson were trying to pick up weak celestial signals using a microwave receiver and a large antenna. During this, they found a last stubborn bit of noise that wouldn’t go away and had stable wavelength as the earth rotated. This suggested that the noise did not originate in the solar system. At the same time, Robert H. Dicke was investigating the Big Band Theory and needed to find some microwaves present to support the theory. The mysterious microwaves turned out to be whats left over 10 to 20 billion years of the expansion of space, being the remains of the heat of the Big Bang.
What is CMBR?
Cosmic Microwave Background Radiation is used as evidence for the Big Bang. CMBR is the remains of the heat energy from the Big Bang, spread thinly across the whole Universe.
What is the light spectrum?
The light spectrum represents colors of light based on their wavelength and frequency.
What is wavelength?
The wavelength of a wave is the distance between a point on one wave (crest) and the same point on the next wave (crest). It is how stretched the wave is.
What is frequency?
The frequency of a wave is the number of waves by a source each second or how many times the wavelength peak passes a certain point in a second.
Describe the relation of wavelength and frequency to a light spectrum.
On the light spectrum, closer to the blue end the wavelengths are shorter so the frequency is higher. While closer to the red end, the wavelengths are longer, so the frequency is lower.
Describe the basis of redshift and how it is used to show that the universe is expanding.
All stars emit light. When we look at the spectrum of light, black lines are visible. These black lines show where helium in the star has absorbed the light. In the spectrum of a more distant star, the lines have shifted towards the red end - the wavelength of the light waves has increased and so the frequency has decreased. This red-shift indicates that these galaxies are moving away from us.
Relation of redshift to Doppler Effect.
Redshift occurs because of the doppler effect.
What is the Doppler Effect?
The Doppler Effect is a change in the frequency of a wave relative to an observer caused by moving the wave’s source. For example, in space, relative to our position on Earth other galaxies (not stars as they are gravitationally bound by gravity in our galaxy) are becoming more distant, therefore, red, because they are emitting light (wave source) that is moving.
Scientists have also found that the farther a galaxy is, the faster it moves away.
What is the difference between blue light and red light?
Blue light has a shorter wavelength. Red light has a longer wavelength.
