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----------------- 2706 - HUBBLE CONSTANT - for an expanding Universe ?
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- This expansion rate for the Universe leads to other calculations for the mass / energy in the Universe and the result is that 95 % of the universe is Dark Mass and Dark Energy. You can not say the graduating students in the sciences do not have enough to work on! We do not understand 95% of our home.
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- The expansion rate of the Universe is known as the “Hubble Constant” rate of expansion. To come up with this astronomers observe distant galaxies. Measure the distance they are away from us. And, measure the speed at which they are receding away from us.
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- In the 1980’s the measured value was accepted to be 55 kilometers per second per every mega parsec distance. A mega parsec is 3.26 million light years distance. Put in other more familiar units we are accelerating our rate of expansion by 49,300 mile per hour for every million lightyears distance.
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- This calculation was made by monitoring Cepheid Variable stars in distant galaxies. The luminosity brightness correlates with the periods of their brightness variations. (See reviews about Cepheid Variables to learn more about this)
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- Then, in beginning in 2001 the Hubble Space Telescope made measurements of Cepheid Variables in galaxies over 80 million light years away. These measurements came up with 72 km/sec per mega parsec.
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- Other astronomers used the Cosmic Microwave background radiation measurements to come up with 67 km/sec per mega parsec.
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- In 2018 measuring Type 1a Supernova explosions came up with 73.5 km/sec per mega parsec
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- Astronomers are still disagreeing about this real rate of universe expansion.
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- We have thought that the Universe was expanding since 1935. Ten years earlier in 1925 no astronomers believed the Universe was expanding, everyone thought it was static. But by 1935 almost all astronomers believed the Universe was actually expanding at an ever increasing rate.
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- Edwin Hubble at Mount Wilson Observatory provided the first data. He made no conclusions. He simply stated what he saw. He saw galaxies were not gaseous nebulae but actually groups of individual stars. He saw them to be more distant and outside our Milky Way Galaxy.
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- He saw a redshift in the starlight indicating that the galaxies were moving away from us in all directions. Further, the farther the galaxy was away the faster it was receding. The velocity of these receding galaxies became known as Hubble’s Constant - the rate at which the expansion velocity changes with distance.
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- The other convincing evidence was Einstein’s 1915 General Theory of Relativity. Astronomers began to measure Hubble’s Constant, its symbol was “H”. A value of 60 kilometers pre second per mega parsec means a galaxy at a distance of one mega parsec will be moving at 60 kilometers/ second away from us. A mega parsec is an astronomer’s distance measurement of 3,600,000 lightyears.
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- The inverse of Hubble’s Constant is the expansion age of the Universe:
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----------------------- 1/60 = 0.0167 seconds/kilometer/3.26*10^6 lightyears.
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----------------------- Lightyear = 9.461 * 10^12 kilometers. 0.0167 * 30.84*10^18 = 5.15 * 10^18 seconds / 3.16 * 10^7 seconds/year = 16.3 * 10^9 years.
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----------------------- Maximum age of the Universe is 16.3 billion years, using H = 60
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- A different average expansion rate yields a different age for our Universe:
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----------------------- H = recession velocity / separation distance = 72 km/sec/Mpc
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----------------------- Time since the Big Bang = separation distance / recession velocity
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----------------------- velocity = distance / time
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----------------------- Time = distance / velocity
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----------------------- Time since the Big Bang = 1 / H = 1 / 72 = 13.7 billion years
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- The Hubble Constant has not been constant over the life of the Universe because expansion was faster in the past and has decreased to today’s rate because of the mutual gravitational attraction of all the galaxies. So expansion age is the maximum age of the universe. H = 60km/sec/mpsc is an average believed to be “ constant”. But, today’s data also tells us that “H” is “accelerating” at an ever growing rate , hardly constant over time.
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- In the 1930’s taking this idea backwards in time lead astronomers to believe in the Big Bang Theory.
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- In 1967 two radio astronomers discovered the Cosmic Microwave Back ground radiation which was convincing evidence that the Big Bang really happened.
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- The Hubble Space Telescope was launched in 1990. “H” was estimated to be between 58 and 72 km/sec/mpc, setting the age of the Universe to be 13 to 14 billion years old.
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- One team studying Cepheid stars in 2001 narrowed “H” down to 72 + or - 8 km/sec/mpc, or 13 billion years old. Another team of astronomers studying supernova came up with 58 + or - 5 km/sec/mpc. A third team studying the Cosmic Microwave background came up with 72+ or - 0.05 km/sec/mpc, 13,700,000,000 years old.
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- Now, look at the palm of your hand. You see a flesh made up of atoms. You can not see the atoms, and you not see the quarks and electrons that make up those atoms. But, the quarks and electrons in your hand are 13,700,000,000 years old. They were created from energy in the Big Bang.
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- They are the beginning fundamental particles. As the Universe expanded and cooled these particles fused into hydrogen and helium atoms. Later these atoms fused into the higher level elements such as oxygen and carbon in the enormous explosions of stars that were fusing hydrogen and helium for energy.
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- Our Sun is medium sized and burns more slowly lasting 10 billion years. Giant stars 100 times larger than our Sun live only 10 million years then run our of hydrogen/helium fuel and as explode as supernovae.
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- The debris that blasts into the stellar space gathers as gas clouds and forms another star containing these higher level elements. The proteins that make up the flesh in your hand was made from these explosions from billions of years ago. You are older than you think. And, thinking is what discovered your true age. You owe it to the stars that you can think.
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------------------------ Other Reviews about the Hubble Constant of expansion:
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- 2607 - HUBBLE CONSTANT - leads to the age of the Universe? Once you figure out that the Universe is expanding, all you need to do is measure the expansion rate today and use the laws of physics to determine how the expansion rate must have changed over time. You do the calculating backwards and go all the way back until you achieve the conditions of the hot Big Bang itself.
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- 1739 - How fast is the Universe Expanding? This review explains Hubble’s Constant for the velocity of space expansion and how working backwards gives us the age of the Universe. Hubble’s Constant not only places galaxies in space, it places them in time as well. Edwin Hubble discovered that galaxies were all receding away from us. The further away the galaxy was the faster it was receding. His Constant was a velocity per every million lightyears of space between us and the galaxy.
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- April 13, 2020 773 2706
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--------------------- Wednesday, April 15, 2020 -------------------------
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