Cosmology

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Cosmology Noun

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[koz-mol-uh-jee]

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Cosmology

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The scientific study of the universe's origin, large-scale properties, evolution, and ultimate fate as a whole system.

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Example: This diagram uses a balloon analogy to show that as space expands over time, the wavelength of light from distant galaxies stretches, appearing 'redshifted'.

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Big Bang Theory Noun

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[big bang thee-uh-ree]

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Big Bang Theory

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The leading scientific theory that the universe originated from an extremely hot, dense state and has been expanding since.

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Example: This diagram shows that the universe started from a single, hot, dense point (the Big Bang) and has been expanding and cooling ever since.

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Dark Matter Noun

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[dark mat-er]

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Dark Matter

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A non-luminous form of matter believed to constitute a large portion of the universe's mass, detectable via gravity.

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Example: This diagram shows our Milky Way galaxy is surrounded by a much larger, invisible cloud called a 'dark matter halo,' where most of its mass is.

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Dark Energy Noun

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[dark en-er-jee]

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Dark Energy

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A hypothetical form of energy believed to be responsible for the accelerating expansion of the universe.

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Example: This image shows that as the universe (the balloon) expands, the galaxies within it move farther apart, illustrating the effect of dark energy.

Front

Doppler Effect Noun

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[dop-ler uh-fekt]

Back

Doppler Effect

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The change in a wave's frequency for an observer moving relative to the source of the wave.

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Example: When a light-emitting object moves, the light waves it sends out are compressed (blueshift) if it's approaching an observer, or stretched (redshift) if it's moving away.

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Redshift Noun

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[red-shift]

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Redshift

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The displacement of an object's light spectrum toward longer wavelengths, indicating it is moving away from the observer.

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Example: As the universe expands over time, the space between galaxies stretches, causing the wavelength of light traveling through it to also stretch and shift toward red.

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Universe Noun

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[yoo-ni-vurs]

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Universe

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The entirety of existing matter, energy, space, and time, encompassing all galaxies, stars, and other celestial bodies.

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Example: This diagram shows that the universe started from a single point (the Big Bang) and has been expanding ever since, causing galaxies to move farther apart.

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General Relativity Noun

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[jen-er-uhl rel-uh-tiv-i-tee]

Back

General Relativity

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Einstein's theory describing gravity as a distortion of spacetime caused by the presence of mass and energy.

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Example: A massive object, like a planet or star, bends the fabric of spacetime around it, which is how gravity works in general relativity.

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Cosmological Principle Noun

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[koz-muh-loj-i-kuhl prin-suh-puhl]

Back

Cosmological Principle

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The assumption that the universe, on a large scale, is uniform (homogeneous) and looks the same in all directions (isotropic).

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Example: This diagram shows that on a large scale, the universe looks uniform (homogeneous), and even when you zoom in on a large section, it still looks the same.

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Homogeneous Adjective

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[hoh-muh-jee-nee-uhs]

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Homogeneous

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A state of being uniform in structure or composition throughout, with matter being evenly distributed on large scales.

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Example: This image shows that when sugar is mixed with water, it dissolves completely to form a uniform (homogeneous) mixture, unlike sand which does not dissolve.