The Big Bang

Front

Quark Noun

---

[kwark]

Back

Quark

---

A fundamental subatomic particle that combines to form composite particles like protons and neutrons, which are constituents of matter.

---

Example: This diagram shows how fundamental particles called quarks (two 'up' and one 'down') are held together to form a larger particle, a proton.

Front

Big Bang Noun

---

[big bang]

Back

Big Bang

---

The cosmological theory describing the universe's origin from an extremely hot, dense point that expanded about 13.8 billion years ago.

---

Example: This diagram shows the Big Bang as a single starting point from which the entire universe began to expand, with galaxies moving farther apart over time.

Front

Redshift Noun

---

[red-shift]

Back

Redshift

---

The stretching of light to longer wavelengths, which indicates that a celestial object is moving away from the observer.

---

Example: This diagram shows that light from distant galaxies is stretched. The dark lines in their light spectrum are shifted towards the red end compared to a reference, and the farther the galaxy, the bigger the shift.

Front

Cosmic Microwave Background (CMB) Noun

---

[koz-mik my-kroh-weiv bak-ground]

Back

Cosmic Microwave Background (CMB)

---

Faint thermal radiation filling the universe, representing the afterglow of the Big Bang, now observed in the microwave spectrum.

---

Example: This image compares maps of the Cosmic Microwave Background (CMB) from three satellites, showing how our view of this Big Bang afterglow improved over time.

Front

Doppler Effect Noun

---

[dop-ler uh-fekt]

Back

Doppler Effect

---

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

---

Example: This diagram shows that as a light-emitting object moves, the waves it sends out are changed. Waves from a receding object stretch out (redshift), and waves from an approaching object bunch up (blueshift).

Front

Wavelength Noun

---

[weyv-lengkth]

Back

Wavelength

---

The spatial period of a periodic wave, measured as the distance between two consecutive corresponding points of the wave.

---

Example: This diagram shows a wave and labels the wavelength as the distance between two consecutive peaks (crests), a fundamental property of light and radiation.

Front

Blueshift Noun

---

[bloo-shift]

Back

Blueshift

---

The compression of light to shorter wavelengths, which indicates that a celestial object is moving toward the observer.

---

Example: This diagram shows a light spectrum's absorption lines shifting toward the blue end, which happens when a light source moves towards an observer.

Front

Cosmological Redshift Noun

---

[koz-muh-loj-i-kuhl red-shift]

Back

Cosmological Redshift

---

A redshift caused by the expansion of space itself, which stretches the wavelength of light as it travels through the universe.

---

Example: As the universe expands over time, like an inflating balloon, the space between galaxies stretches, causing the wavelength of light traveling through it to stretch and shift towards red.

Front

Hubble's Law Noun

---

[huh-buhlz law]

Back

Hubble's Law

---

The observation that a galaxy's recession speed is directly proportional to its distance from the observer, indicating universal expansion.

---

Example: As the balloon (universe) inflates, the dots (galaxies) on its surface move farther apart, showing how the expansion of space causes galaxies to recede.

Front

Hubble Constant (H₀) Noun

---

[huh-buhl kon-stuhnt]

Back

Hubble Constant (H₀)

---

The constant of proportionality in Hubble's Law that quantifies the rate of the universe's expansion at the present time.

---

Example: This graph shows that the farther away a galaxy is, the faster it moves away. The slope of this line is the Hubble Constant (H₀).