Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
|
Big Bang
|
Our entire universe was created when a tiny (billions of times smaller than a proton), super-dense, super-hot mass exploded and began expanding very rapidly, eventually cooling and forming into the stars and galaxies.
|
|
|
Age of Universe
|
13.75 billion years
|
|
|
Evidence for the Big Bang
|
If the distance between galaxy clusters is increasing today, everything must have been closer together in the past.
|
|
|
Isotropy
|
The premise that there is no preferred direction singled out in space (space looks the same in all directions about a point). Isotropy may be tested for by searching for anisotropy in the 2.7 K background radiation.
|
|
|
Homogeneity
|
The premise that physical properties are the same at every point (space looks the same at each point). Homogeneity may be tested for using the homogeneity luminosity test.
|
|
|
Hubble Law
|
In 1929 Edwin Hubble published his landmark discovery that distant spiral 'nebulae' are receding from us at speeds proportional to their distances, implying that the Universe is expanding at a constant rate.
|
|
|
Hubble Constant
|
The constant which determines the relationship between the distance to a galaxy and its velocity of recession due to the expansion of the Universe. The ratio of velocity to distance in the expansion of the Universe, so v = HD.
|
|
|
Cosmic Microwave Background
|
The nearly uniform radiation received from all regions of the sky. It is a radio signal with a temperature of 2.7K, and is thought to be the cooled afterglow of the Big Bang.
|
|
|
Cosmic Inflation
|
The theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density
|
|
|
Cosmic Dark Ages
|
A section of the universe in its expansion since the big bang
|
|
|
Galaxy Collisions
|
Colliding galaxies are common in galaxy evolution. Due to the extremely tenuous distribution of matter in galaxies, these are not collisions in the normal sense of the word, but rather gravitational interaction.
|
|
|
Expanding Universe
|
The expanding universe is a model of the universe in which galaxies are receding from one another at a speed proportional to their separation - it is based on the observed Doppler redshift of distant galaxies.
|
|
|
Accelerating Universe
|
The observation that the universe appears to be expanding at an increasing rate.
|
|
|
Dark Energy
|
Dark Energy is a hypothetical form of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity.
|
|
|
Dark Matter
|
Most of the mass-energy, about 95%, in the universe is 'dark'. By dark we mean that it does not emit any form of electromagnetic radiation. The existence of Dark Matter is inferred indirectly by its gravitational effect.
|
|
|
Four Fundamental Forces
|
Gravitational Force, Electromagnetic Force, Weak Nuclear Force, and Strong Nuclear Force
|
