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Distribution of redshifts and corresponding age of the Universe for gamma-ray bursts detected by NASA's Swift satellite. The new GRB 090423 at a redshift of z=8.2 easily broke the previous record for gamma-ray bursts, and also exceeds the highest redshift galaxy and quasar discovered to date, making it the most distant known object in the Universe. GRB 090423 exploded on the scene when the Universe was only 630 million years old, and its light has been travelling to us for over 13 billion years. Credit: Edo Berger (Harvard/CfA
Red shift is a phenomenon that is the shift in the wavelength of light in the electromagnetic spectrum towards the “red” or infrared section. This is the result of wave mechanics, particularly the Doppler Effect. If you don’t know what the Doppler Effect is, it’s a theory describing the behavior of waves as their source moves away or toward an observer. The theory states that the closer the source of the waves to the observer the shorter the wavelength and frequency of the waves. The opposite also occurs as the source of the waves move away from the observer causing the wavelength of the waves to increase. This theory was first physically explained by Charles Andreas Doppler in 1842 concerning sound waves. It later tested and proven in 1845 by the Dutch scientist Christoph Ballot
The common example used in describing it is the fire engine siren. Most people have heard a siren on a fire truck and noticed that the pitch of the siren changes as the vehicle come towards them and as it leaves. Sound waves with shorter wavelengths sound higher in pitch while sound waves with longer wave lengths have a lower pitch. This is how we are able to know the Doppler Effect is occurring.
The theory also stated from the beginning that this phenomenon occurred for all types of waves. In astronomy it took the research of a man named Armand-Hippolyte-Louis Fizeau to prove that this phenomenon occurred in light as well. Light is also a kind a wave but the wavelengths are visible which gives us the visible spectrum. Fizeau proved it by separating the light from stars into their individual spectrum lines proving that red shift occurs.
This discovery allowed for other advances such as the calculations of stars’ velocities. The theory also helped scientist compile evidence proving the expansion of the universe. The light of galaxies as well could be observed and analyzed to see if the light they emit in general produces the red shift effect. In the present time we use this also in spectroscopy the science of using light to determine the characteristics of a substance such as it elemental composition. Thanks to the Doppler Effect and light waves we now can not only determine, the distance and speed of celestial objects, we can also learn what they are made of even without the aid of probe. This theory has helped to advance astronomy and physics to our current understanding also helping to pave the way for other important theories like the Theory of Relativity.
If you liked this article there are several others on the Universe Today website you might enjoy. There is a great article about red shift being used to map out the near universe in 3D. There is also a great article about it being used to find the most distant gamma burst ever detected.
Sources: ESA, Caltech IPAC
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