![]() Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere. Electromagnetic radiation which was present shortly after the big bang is now observed as background microwave radiation. Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. ![]() Cosmic Background Microwave Radiation (CMBR)Ī second piece of evidence that supports the big bang theory is cosmic background microwave radiation. The light from distant galaxies is red shifted (this tells us the galaxies are moving away from us) and the further away the galaxy the greater the red shift (this tells us that the more distant the galaxy the faster it is moving). The universe then expanded from that point to give us the universe we see today. The big bang theory is that the universe began from a very small initial point. The light is shifted towards the red end of the spectrum, RED SHIFT. The observed wavelength of the light is longer when objects are moving away from us. The colours from short wavelength to long are White light can be split up into its component colours using a prism or diffraction grating. When the light from a galaxy which is moving away from you is observed the wavelength of the observed light appears longer, it moves towards the red end of the spectrum. ![]() Caused solely by the expansion of the Universe, the value of the cosmological redshift. When the sound source moves away from you the wavelength increases and the frequency of the sound decrease (lower pitch). This is known as ‘ cosmological redshift ’ (or more commonly just ‘redshift’) and is given by: for relatively nearby objects, where z is the cosmological redshift, obs is the observed wavelength and rest is the emitted/absorbed wavelength. When the sound source moves towards you to wavelength decreases and the frequency of the sound increase (higher pitch). The SDSS-III Baryon Oscillation Spectroscopic Survey, now nearly complete, is measuring the three-dimensional cosmic structure with 1.35 million new redshifts. As the car approaches you the sound it produces is higher pitched than when it drives away from you, where the sound becomes lower in pitch. This effect can be heard when a formula 1 car drives past you.
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