Physical Science Chapter 28

Big Rip
A model for the end of the universe in which dark energy grows stronger over time and causes all matter to rip apart.

Cosmic background radiation
The faint microwave radiation emanating from all directions that is the remnant heat of the Big Bang.

Cosmic inflation
The moment of the sudden and brief burst in the size of the universe immediately after the Big Band.

Cosmological redshift
The elongation of light waves due to the expansion of space.

Cosmology
The study of the overall structure and evolution of the universe.

Dark energy
An unknown form of energy that appears to be causing an acceleration of the expansion of space; thought to be associated with the energy exuded by a perfect vacuum.

Dark matter
Invisible matter that has made its presence known so far only through its gravitational effects.

Eternal inflation
A model of the universe in which cosmic inflation is not a one-time event but rather progresses to continuously spawn an infinite number of observable universes in its wake.

General theory of relativity
The theory first proposed by Einstein discussing the effects of gravity on spacetime.

Heat death
A model of the end of the universe in which all matter and energy disperse to the point of maximum entropy.

Hubble’s law
The farther away a galaxy is from Earth, the more rapidly it is moving away from us: v= Hxd

Ordinary matter
Matter that responds to the strong nuclear, weak nuclear, electromagnetic and gravitational forces. This is matter made of protons, neutrons and electrons, which includes the atoms and molecules that make us and our immediate environment.

Principle of equivalence
local observations made ina n accelerated frame of reference cannot be distinguished from observations made in a Newtonian gravitational field.

Spacetime
The continuum in which we live, consisting of three dimensions of space plus the fourth dimension of time.

Special theory of relativity
The theory first proposed by Einstein discussing the effects of uniform motion on space, time, energy and mass.

Which depends on distance: a star’s brightness or its luminosity?
The luminosity of a star is the amount of energy it puts out per second. The brightness of the star diminishes with distance.

Summer & winter constellations are different because
the night sky faces in opposite directions in summer and winter.

Polaris is always directly over
the North Pole

The star nearest the Earth is
the Sun

The property of a star that relates to the amount of energy per unity time it is producing is its
luminosity

The longest-lived stars are those of
low mass

We do not see stars in the daytime because
skylight overwhelms starlight

After our Sun burns its supply of hydrogen, it will become a
red giant

A black hole is
the remains o f a giant collapsed star.

The shape of an active starburst galaxy tends to be
irregular

Scientists estimate the age of our universe to be about
14 billion years old. 5