- 2879 - REDSHIFTS - seeing back in time. The redshift tells us how old it is? The age of the Universe is 13,700,000,000 years. The oldest galaxy we can see formed 13,000,000,000 years ago. The Universe was only 5% of its current age when this galaxy formed. If a human was 80 years old it would be analogous to her viewing a picture of herself when she was only 4 years old. The most distant quasar galaxy had a redshift of 7. That means the signal left the galaxy 770,000,000 years after the Big Bang
--------------------------- 2879 - REDSHIFTS - seeing back in time.
- Since 1676 astronomers have known that light travels at a finite speed. Using the moons of Jupiter as a pendulum clock, astronomers measured the difference in time for the moons to pass Jupiter’s horizon at six month intervals of the year.
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- In six months the Earth orbits at a point closest to Jupiter to a point furthest from Jupiter. That distance being the diameter of Earth’s orbit around the Sun. The time difference measured divided by that distance calculated the speed of light.
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- 336 years later our measurements put the speed of light at 186,282 miles per second.
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----------------------- 670,633,500 miles per hour
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---------------------- 5,880,000,000,000 miles per year
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- 5.88 trillion miles is the distance light travels in one year.
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- If astronomers observe a galaxy 1 million lightyears away, they are looking at that galaxy as it was 1 million years ago. That is how long it took for the galaxy’s light to reach us.
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- Through these observations astronomers have learned that the Universe in the past appeared much different than the Universe we see today.
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- In the beginning the Universe was only primordial gas, hydrogen and helium. It was only after the first stars formed out of this gas that nuclear fusion created the heavier elements.
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- The first stars were giants, 300 to 400 Solar Mass. Our Sun is 1 Solar Mass. These giant stars had short lives due to their immense gravity and rapid fusion of their hydrogen and helium fuel.
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- When they ran out of fuel they collapsed and exploded into a supernova with immense heat and pressure that fused the lighter elements into heavier elements. Stars that formed later out of the interstellar medium created from the first stars contained these heavier elements.
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- Each element is different. The light spectrum from stars contains absorption lines that are fingerprints for each element. Each absorption line pattern represents specific wavelengths of energy absorbed by an electron as it jumps to higher excited orbits.
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- Every element has its own unique set of electrons in orbit. Elements can be identified in the light spectrum using these “fingerprints” of absorption lines.
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- In 1950 Quasars were first discovered. “Quasi-Stellar Objects” had spectral absorption and emission lines that were unlike any known elements found on Earth. At first they were thought to be newly discovered elements.
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- It was not until 1960 that Caltech in Pasadena discovered that these fingerprints were really known elements that had their wavelengths “redshifted” to longer wavelengths due to the expanding space.
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- By 1980 Quasars were understood to be the central regions of galaxies that contained massive Blackholes. Billion Solar Mass Blackholes consume vast quantities of gas. The gas forms in an accretion disk orbiting just outside the Event Horizon. The rotating gas heats up and emits intense energy that astronomers see as a point source of light from a Quasar.
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- The earliest Quasar discovered so far has a redshift of 7.085 times, which means it exists just 770,000,000 years after the Big Bang. This tells us that galaxies first formed before this time.
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- Astronomers started using the fingerprints of neutral hydrogen to look even further back in time. Neutral hydrogen emits photons at a wavelength of 21 centimeters. The redshifts for these longer wavelengths require telescopes using low-frequency radio waves. Using this technique the most distant galaxy was found at 480,000,000 years after the Big Bang.
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- The table that follows lists some of these most distant discoveries:
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-------------------------------------------------------- Redshift ----- Years after BB
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--------- 1960 ------------- Galaxy --------------- 0.461 --------- 8.9 billion
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--------- 1965 ------------- Quasar --------------- 2.018 --------- 3.3 billion
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--------- 1974 ------------- Quasar --------------- 3.53------------ 1.8 billion
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--------- 1987 ------------- Quasar --------------- 4.01 ---------- 1.6 billion
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--------- 1997 ------------- Galaxy --------------- 4.92 ----------- 1.2 billion
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--------- 1998 ------------- Supernova ----------- 0.83 ----------- 6.7billion
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--------- 2001 ------------- Quasar --------------- 6.28 ----------- 0.9 billion
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--------- 2009 ------------- Supernova ---------- 2.357 ---------- 2.8 billion
--------- 2010 ------------- Galaxy --------------- 8.56 ----------- 0.6 billion
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--------- 2011 ------------- Quasar --------------- 7.085 ---------- 0.77 billion
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--------- 2011 ------------- Galaxy Cluster ------ 2.07 ---------- 3.2 billion
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--------- 2011 ------------- Gamma Ray Burst -- 9.4 ----------- 0.52 billion
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--------- 2011 ------------- Galaxy ---------------- 10 ------------ 0.48 billion
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--------- 2012 ------------- Supernova Type 1a -- 1.55 ---------- 4.2 billion
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- From the table above Gamma Ray Bursts have been discovered occurring 520,000,000 years after the Big Bang.
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- A Galaxy Cluster existed 3,200,000,000 years after.
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- The most distant Quasar at a redshift of 7 at 770,000,000 years after.
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- The most distant galaxy at a redshift of 10 at 480,000,000 years after.
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- Of course the greatest redshift object is the CMB at 1,100 redshift and 380,000 after the Big Bang. This object is the Cosmic Microwave Background Radiation that was emitted in the infrared wavelengths when hydrogen atoms first lost ionization and became neutral allowing the photons to escape. Today we detect their redshifted light in the microwave end of the electromagnetic spectrum.
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- To see backwards in time even further astronomers need to detect even longer wavelengths. This requires even bigger telescopes. A telescope planned for Chile is 24.5 meters in diameter. One planned for Mauna Kea, Hawaii is 30 meters. A European telescope also planned for Chile is 39.3 meters.
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- It is race to ever higher redshifts to see farther back in time. Only in astronomy do you get to do this sort of thing.
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- The age of the Universe is 13,700,000,000 years.
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- The oldest galaxy we can see formed 13,000,000,000 years ago. (see Review 1603)
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- The Universe was only 5% of its current age when this galaxy formed. If a human was 80 years old it would be analogous to her viewing a picture of herself when she was only 4 years old.
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-------------- 4 / 80 = 0.05 -------------- .7 / 13.7 = 0.051 = 5.1%
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- The time that light has been traveling towards is 13 billion years. Space has been expanding during that time. Expanding space stretches out the wavelength of the light. Longer wavelength are towards the red end of the light spectrum, thus the “ redshift” of light.
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- Light could leave the galaxy in the ultraviolet wavelengths and arrive at our telescopes in the far infrared. The time that has elapsed is a function of the amount of redshift.
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- Here is a formula that is given for calculating the elapsed time given the redshift. It is polynomial of the 5th order where “z” is the redshift.
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- time ( z ) = 0.0002 z^5 - 0.0072 z^4 + 0.1301 z^3 - 1.143z^2 + 5.014 z + 3.7677
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- A graph can be constructed with billions of years on the y-axis and redshift on the x-axis. The graph becomes a linear function at higher redshifts. The graph is from 1 to 15 redshift. The astronomers are working between 9 and 12 redshift.
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- Astronomers would like to be using a simpler equation for their calculations.
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------------------- Time (z = 9 ) = 13.11 billion years.
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------------------- Time ( z = 12 ) = 13.29 billion years.
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- Construct a straight line between these 2 points and construct a linear equation for that line that will give time as a function of redshift.
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--------------------------- y = mx + b, is the general equation for all straight lines.
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--------------------------- Time (z) = mz + b
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---------------------------- Where “ m” is the slope of the line and “b” is where the line crosses the y-axis, where x = 0. First let’s calculate the slope of the line connecting the 2 points:
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---------------------- slope = m = 13.29 - 13.11 / 12 - 9 = 0.18 / 3 = 0.06
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- Next we find the intersection of the line with the y-axis:
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----------------------- 13.29 - b / 12 = m = 0.06
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----------------------- 13.29 - b = .72
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----------------------- b = 12.57
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------------------ Time (z) = 0.06(z) + 12.57
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------------------ Time (8.6) = 0.516 + 12.57 = 13.086 billion lightyears
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------------------ Time (9) = 0.54 + 12.57 = 13.11 billion lightyears
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------------------ Time (11.9) = 0.714 + 12.57 = 13.1284 billion lightyears
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------------------ Time ( 12 ) = 0.72 + 12.77 = 13.29 billion lightyears
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- Note in a picture of deep field galaxies and the redshifts are ranging from 8.6 to 11.9. Their distances in billions of lightyears can be easily calculated with this equation.
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- I am puzzled by the 5th order polynomial when I us it to calculate the time.
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------------------- Time ( 9 ) = 15.7 billion years
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------------------- Time ( 12 ) = 24.7 billion years
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------------------- Time ( 15 ) = 48.3 billion years.
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- Apparently many more terms are needed in this equation to get better answers. Over the range of 9 to 12 our linear redshift equation works very well. An announcement will be made shortly, stay tuned, until I find the answer.
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- Redshifts less that 1.4 can use a much more intuitive formula that calculates the receding velocity of the galaxy. The further away a galaxy is the faster its receding velocity because there is more space between us that is expanding.
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------------------ The ratio of receding velocity, “ v” to the speed of light , “c” is:
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------------------ v / c = z^2 +2z // z^2 + 2z + 2
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- where z = 1.4 ------ v / c = 1.4^2 +21.4 // 1.4^2 + 21.4 + 2 = 4.76 / 6.76 = 70%
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- The ratio of the expanding velocity to the speed of light = 70%
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- The galaxy is receding at a velocity of 70% *c = 210,000 meters per second.
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- The lookback time = 9,000,000,000 years
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- The co-moving distance = 13,000,000,000 lightyears
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- The Universe’s age = 42% of its current age
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- The Universe age when the light left the galaxy = 5,750,000,000 years.
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- The Cosmic Microwave Background light has a redshift of 1,100. It has a lookback time of 13,700,000,000 years. A co-moving distance of 46,000,000,000 lightyears.
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- I hope all this does not make you feel old. You are made of very old stardust when you get right down to it
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------------------------------ Other reviews about redshifted light:
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- 2876 - REDSHIFT - found in orbiting neutron stars? A theory in physics and astronomy predicted by Albert Einstein in 1906 has been verified using a double star system about 29,000 light years from Earth. This phenomenon in physics, called a 'gravitational redshift,' has been well documented in our Solar System, but it's been more elusive for the stars.
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- 2698 - REDSHIFT - explains the Universe expansion? The Universe is expanding. How do we know that. We measure the wavelength of light and it is getting stretched out as it travels through space to reach us. As wavelength stretches the photons loose energy. If Gamma Wave wavelengths are emitted after the Big Bang by the time they reach us they have been redshifted, wavelength stretched out, into the microwave wavelengths.
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- 1713 - Colors change for far away galaxies. We can calculate their radial velocity by the amount of shift that happens to colors of light as it travels through expanding space. Using Hubble’s constant rate of space expansion we can calculate the distance to the galaxy.
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- 1695 - Measuring astronomical distances
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- 1603 - Finding the farthest galaxy. How spectroscopy is used to measure the distance to the farthest galaxies?
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- October 27, 2020 1500 1501 2879
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--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
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--- to: ------ jamesdetrick@comcast.net ------ “Jim Detrick” -----------
--------------------- --- Tuesday, October 27, 2020 ---------------------------
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