red shift

Thân thiện

A scientist points to a red shift on a distant galaxy's spectrum chart.

Definition

1. Noun:
   • A cosmological phenomenon: "Red shift" refers to the observed shift of light from distant galaxies toward longer wavelengths, specifically the red end of the electromagnetic spectrum. This is a key piece of observational evidence in astronomy indicating that these galaxies are moving away from us, supporting the theory of an expanding universe.

Usage Examples

• Noun:
  • The astronomer measured the red shift of the distant quasar.
  • The greater the red shift, the faster the galaxy is receding and the farther away it is.

Advanced Usage

• "Cosmological red shift": The red shift caused by the expansion of space itself, as opposed to the Doppler effect from motion through space.

  • The cosmological red shift is a direct consequence of the stretching of spacetime.

• "Gravitational red shift": A shift toward longer wavelengths caused by a strong gravitational field, a prediction of Einstein's general theory of relativity. (Note: This is a related but distinct phenomenon from the primary cosmological meaning).

  • The gravitational red shift of light escaping a black hole is extreme.

Variants and Related Words

• Redshift (n): A common alternative spelling as a single word.

  • The data confirmed a high redshift for the galaxy.

• Blueshift (n): The opposite phenomenon, a shift toward shorter (blue) wavelengths, indicating an object is moving toward the observer.

  • The star exhibited a slight blueshift, showing it is moving closer to our solar system.

Synonyms

• Doppler shift (toward the red): Specifically refers to the wavelength change due to relative motion away from the observer. (Note: Cosmological red shift is analogous to, but fundamentally distinct from, a Doppler shift).

Related Terms and Concepts

• Hubble's Law: The observational correlation that a galaxy's recessional velocity (indicated by its red shift) is proportional to its distance.

  • Hubble's Law is formulated using measurements of galactic red shifts.

• Recessional velocity: The speed at which a celestial object moves away from an observer, calculated from its red shift.

  • The red shift was used to compute the galaxy's recessional velocity.

Học thuật

Noun

1. (astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding

Từ đồng nghĩa

• redshift