Dictionary of Space Concepts

Short Definition:

Hubble's Law is a concept formed by Edwin Hubble, defining a positive relation between the distance and the speed of galaxies moving away from earth. The further they are, the faster they move away. This theory was a base to observe the expansion of universe.

Detailed Definition:

Hubble's law defines a relation between distance of galaxies and their speed of moving away from each other. The concept was observed through detection of redshift emitted by these galaxies, visible from earth. In simpler terms, the galaxies emit light on a spectrum further towards the red extreme, which can be observed by comparing measurements from different times, to calculate that the light has changed its wavelength and frequency, thus shifting on the visible light spectrum. The theory proves that the universe is constantly expanding, and thus it contributes to the Big Bang Theory. The constant movement of galaxies away from earth and each other, points to the increase of space in the universe. The theory also derives a so called, Hubble's constant which is a measure of how fast a given galaxy moves away at a given distance, and it comes out to around 70 (km/s)/Mpc which translates to expansion of 70 kilometres per second for every megaParsec of distance from the galaxy. Thus, for a galaxy 1 megaParsec away from earth, the structure moves away at a speed of 70 km/s.

Etymology:

Hubble's Law comes from the last name of the physicist Edwin Hubble.

Sample Sentence(s):

1. Hubble's Law contributed largely to the theory of relativity.
2. Hubble's Law proves that the universe is constantly expanding.

Translations:

French - Loi de Hubble

German - Hubbles Gesetz

Italian - Legge di Hubble

Polish - Prawo Hubble'a

Swedish - Hubbles lag