- This is an amazing picture that you will just have to think about for some time before you begin to comprehend it. The picture is 1,000 billion pixels. Each green dot is a galaxy. It goes back in time to half the age of the Universe, over 6 billion years. Each green dot represents 100’s of billions of stars. Likely 10% of those stars have planets. The most incomprehensible think in the Universe is the fact that here you are trying to comprehend it.
- The 1,000 billion pixel picture would fill 500 high definition televisions. The picture is produced by the Sloan Sky Survey. The data collected goes back 6,000,000,000 lightyears, halfway to the Big Bang.. The expanding Universe creates a redshift of these galaxies from 25% to 75% expansion of their light’s wavelengths. The greater the distance the greater the wavelength because more of the light’s time was spent in expanding space. There are over 1,500,000 galaxies in the picture.
- The purpose of the Sloan Sky Survey was to create a 3 dimensional view of the cosmos. To learn how galaxy clusters form in the fabric of space-time. To learn how the Universe is expanding over time. There are sound waves imbedded in this clustering data that can be used to calculate the amount of ordinary matter, relative to the amount of Dark Matter, relative to the amount of Dark Energy, and relative to the amount of neutrinos in the Universe.
- The clustering data could even help astronomers pin down the mass of the neutrino. Originally astronomers thought neutrinos were massless. Later discoveries have determined that neutrinos have a very small mass. How much is still under investigation. This data has already shown that the maximum possible mass for a neutrino is 0.3 electron volts, equivalent to 5 *10^-34 grams.
- The data shows that there are “luminous galaxies” that are much brighter than the average galaxy. Sloan data has identified 900,000 of these luminous galaxies. Since they shine brighter they can be seen at greater distances. The brightness of these galaxies was measured in 5 different colors. By analyzing the redshifts of each of these color wavelengths astronomers can calculate the distance to each galaxy.
- In doing this calculation an issue astronomers had to overcome was the starlight in our own galaxy that was blocking the view of the more distant galaxies. To get the proper estimates of galaxy clustering the effects of foreground stars had to taken in to account. When the 3 dimensional picture emerges out of this data the imprint of sound waves in the early Universe emerge as a clear pattern. The clustering of galaxies are a result of the sound oscillations compressing and rarifying densities of ordinary matter. It is called baryon acoustic oscillations.
- The Cosmic Microwave Background radiation displays this same pattern when the Universe was only 300,000 years old. That is 13.4 billion years ago. The Sloan data goes back 6 billion years ago. By comparing the two data sets astronomers can calculate the expansion of the Universe over that period of time.
- Most of the galaxies are “red galaxies”, older galaxies because they contain only red stars. All the younger blue and yellow stars have exhausted their nuclear fuel and are gone.
- Plotting the data in an angular power spectrum allows astronomers an tell how matter statistically varies in density across the sky. The density waves are sound waves from the early expansion of the Universe. The waves have a fundamental frequency and harmonic frequencies. From these patterns astronomers can determine that 50,000 years after the Big Bang the density of matter and the density of radiation were exactly equal. After that time matter could dominate and structures could begin to form.
- By about 300,000 years after the Big Bang the hot, liquid-like soup of matter finally cooled enough for neutral atoms to form into hydrogen and helium atoms. When the positive and negative charges were neutralized the photons of radiation were free to escape the soup and begin to travel into the cosmos. Before that time the Universe was opaque, like a white storm cloud that you can see the surface but you can not see inside.
- The density sound pattern of matter density peaks every 450 million lightyears. These peaks are the direct descendants of density fluctuations that started in the early Universe. From this pattern astronomers can conclude that Dark Energy is 73% of all the mass-energy in the Universe. Dark mater is 23% and Ordinary Matter only 4%. The uncertainty of these conclusion is < 2%.
- Everything we come in contact with and believe we understand is ordinary matter. Over 95% of the Universe is something else that we do not understand. It is “ dark”. An announcement will be made shortly, stay tuned.
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707-536-3272, Wednesday, January 18, 2012
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