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----------------------------- 2196 - - Discovering the age of the Universe.
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- The discovery of radioactivity reveled the existence of previously unknown sources of energy and unknown laws of physics. During radioactive decay electrons and protons are ejected along with gamma ray radiation. It is the Weak force that was holding those protons and electrons together in the form of neutrons inside the nucleus. It is the Strong force that holds two protons together in the helium nucleus. These ejected particles from the nuclei were first known as alpha rays.
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- Radioactive decay is a natural process and it is responsible for much of the molten heat at the center of our planet. Uranium 238 is 99% or all naturally occurring uranium on Earth. It has a half life of 4,510,000,000 years. This happens to be the approximate age of the Earth.
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- Therefore, in Earth’s beginning there was twice as much U-238 as there is today. Uranium 235, a different isotope of uranium containing 3 fewer neutrons, makes up 0.7% of all naturally occurring uranium. It has a half life of 713,000,000 years.
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- By measuring the relative abundance of different radioactive isotopes scientists can date the origin of the sample. Using this technique scientists have estimated the oldest natural rocks found on Earth to by 3,800,000,000 years old. We said natural rocks because we meant not to include meteorites that have come to us from outer space. These rocks have been dated at 4,500,000,000 years. And, we think they are the same age as the Earth.
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- The energy of uranium was put there by an exploding supernova that produced such an enormous shockwave as to compress the outer layers of the star into higher lever, or heavier, elements. The star itself uses fusion and can only produce elements up to iron in atomic weight.
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- All elements lighter than iron release energy when fusion occurs. Iron is the first element to absorb energy when fusion occurs. When a star starts the fusion of iron its whole process of existence is reversed. Instead of releasing energy to counteract the pressure of gravity it absorbs energy and for the conservation of energy to be maintained this loss of energy must be made up by the collapse of gravitational energy.
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- This whole process of collapse takes less than one second. The bounce of the collapsing star creates a great shockwave that expands into interstellar space at velocities approaching the speed of light. The gas and particle compression that occurs as this shock wave smashes into the elements is what creates the higher isotopes of uranium (as well as all the other heavier than iron elements). Radioactive decay is the timed release of this shockwave energy. Although the decay process for an individual particle, a neutron, is random the statistical average of the decay in a sample of uranium follows this statistical average, known as the half-life.
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- If we make this same radioactive material ratio measurements on the stars of our Milky Way galaxy, using spectroscopy, we can calculate a lower limit for the age of the Milky Way. It must be older than 8,000,000,000 years, twice as old as Earth and our Solar System. If we assume that supernovae have been exploding at the same rate as we see today we can calculate the upper limit of 13,000,000,000 years.
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- When scientists make calculations for the birth of globular clusters of galaxies they get 15,000,000,000 years ( + or - 3 billion years).
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- The birth of the Universe, the Big Bang, has been interpreted as a super radioactive process. The Universe starting as a single atom with an atomic weight equal to the total mass of the Universe. The Universe we see is the result of repeated fission of this super atom. The diameter of the nucleus of this super atom would have been 30 times the diameter of our Sun. This dimension illustrates how much empty space exists inside every atom if we can condense the whole universe into this size. This was a 1920 theory by Lemaitre, published in 1946.
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- Unfortunately this concept became interpreted too literally. It was seen as an explosion of mass and energy rather than the birth of space and time. All the scientists at that time were trying to use Einstein’s equations for relativity to calculate the Big Bang process and the true age of the Universe. Including Einstein himself.
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- Einstein’s equations included the cosmological constant that he added to keep the Universe flat and static with the equation results. He later called it his greatest blunder when he learned from Edwin Hubble’s work that the universe was not static but expanding.
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- It was not until the 1960’s that new knowledge was added to our understanding of the Age of the Universe. This was the discovery of the Cosmic Microwave Background Radiation. This radiation is the leftover heat that occurred when the Big Bang first released its radiation. The radiation has cooled to the point that instead of gamma ray radiation at millions of degrees temperature it is microwave radiation at 2.7 degrees Kelvin, -270.3 C.
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- The cosmic radiation may have started out uniform in temperature, however, as it spread out and interacted with galaxy clusters which contain interstellar gas at 100,000,000 degrees. This interaction boosts the energy of those photons to shorter wavelengths. That is the radiation passing through a galaxy cluster got a bit hotter. Counter intuitive to what we see the radiation gets boosted outside the range of our microwave receiver and it is effectively gone. It appears cooler rather than hotter in our microwave background picture. This apparent change of temperature in our picture is only .01%.
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- The math of how these temperature variations are interpreted is beyond me. It involves computer modeling and much error analysis and many assumptions (inspired guesswork) that is over my head.
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- This interpretation is also compared with several other methods used to date the Universe. As of the year 2000 the age was 13,400,000,000 years (+ or - 1.6 billion years). As of 2005 it is 13,700,000,000 years and waiting for the next new discovery. The time is incomprehensible to our lives. And, the fact that we can comprehend the age of the Universe is truly amazing.
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- December 3, 2018 612
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-------------------------- Monday, January 7, 2019 --------------------------
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