------------------------------- 2737 - QUASAR - the most distant light?
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- That speed of light is an idea that is hard to wrap your mind around. Astronomers are always looking at “history“. And, at this most distant past they are looking at near the birth of the Universe. The radius of the visible Universe is 13 billion lightyears. Beyond that we will never see.
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- What we see is not only light that has traveled that far, it is light that is that old. The idea that the distant galaxy is today that much farther away does not mean that the galaxy is speeding away faster than the speed of light. It is the fact that all that space that is between us is expanding at an accelerating rate. The more space that exists between us the faster the acceleration that is occurring.
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- There objects that are farther away but we have to wait for their light to reach us. It is traveling over that greater distance in lightyears. Astronomers know there is a limit that is the “visible” universe and beyond it the light has yet to reach us.
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- If stuff and galaxies keep expanding beyond the boundary where light will never reach us, then how big is the total, invisible universe? Using this theory called “cosmic inflation” we can come up with the estimate that the total universe is 300, billion, trillion times larger that the “visible universe” But, that is theory about something we will never know.
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- Astronomers estimate that the visible universe has a density of 5 atoms per cubic yard. If that were a true average then there are 10^56 tons of matter (atoms) in the visible universe. And, there are 10^84 photons of light. You can check me on that.
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- If the universe is expanding what is the energy that is causing this expansion? It seems to be an inherent energy in “space” itself? It is the opposite of gravity being some kind of repulsive energy versus gravity’s attractive energy. Astronomers simply call this mysterious energy “ Dark Energy”.
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- It is causing the distance between galaxies to be constantly expanding. And, new evidence is telling us that this expansion is accelerating faster and faster.
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- Does this mean that all space is expanding? No, gravity over powers this expansion where distances between masses, or between galaxies is small enough. The strength of gravity decreases as the square of the distance between masses. Dark Energy is “space” expanding that has the same strength regardless of distance of separation.. When the distance is great enough, when there is enough space of separation, then, Dark Energy takes over from the weaker force of gravity.
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- There are other forces that overcome the forces of gravity and dark energy. At the smallest distance scales the electromagnetic force that holds electrons in atoms and the Strong and Weak Nuclear forces that hold the nucleus of atoms together overpower these other natural forces at their smallest atomic distances.
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- Where gravity is at its most powerful is at the center of galaxies. Quasars are “active” blackholes at the center of these galaxies. Our Milky Way Galaxy has an inactive blackhole at its center. We happen to be orbiting about 25,000 lightyears away from this center and are very happy that it is no longer an active quasar.
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------------------------ To learn more about Quasars see these earlier Reviews:
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- 2506 - QUASARS - extreme blackholes? How do astronomers see the brightest objects in the Universe that are the farthest away? It is the closest thing we have to a time machine. The expansion of space over cosmic distances stretches the wavelengths of visible light making the light redder and redder until is in the infrared part of the spectrum.
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- 2496 - QUASARS - blackholes with personalities. Quasars are high-energy sources in the heavens that astronomers discovered over 80 years ago. They have remained mysteries to this day, however we certainly know a lot more about them.
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- 2490 - QUASARS - light from distant past? - Quasars are blackholes with personalities. A lot of different personalities. Many of the different objects in the Universe that astronomers have identified are actually the same thing, Quasars that are different sizes, different ages, and viewed from different perspectives.
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- 2359 - QUASAR - the island Universe. Quasars are high-energy sources in the heavens that astronomers discovered 80 years ago.
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- 2286 - QUASARS - the hosts of super massive blackholes. Quasars are the most powerful radiating objects in the Universe. They are exceedingly bright while at enormous distances. Their distances are judged by the redshift of their light spectrum. Greater distances mean farther back in time. Today they are called Active Galactic Nuclei known to host super massive blackholes.
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- 2239 - QUASARS - The farthest stars. The Hubble Space Telescope has discovered the brightest quasar ever seen in the early Universe. After 20 years of searching, astronomers have identified the ancient quasar with the help of strong gravitational lensing. This unique object provides an insight into the birth of galaxies when the Universe was less than a billion years old.
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- 2063 - Quasars and Binary Stars. Quasars shine so brightly that they eclipse the ancient galaxies that contain them. Quasars are distant objects powered by blackholes a billion times as massive as our Sun. Most of the quasars have been found to be billions of lightyears away. Because it takes light time to travel, studying objects in space functions much like a time machine. More than 80% of all stars are members of multiple star systems containing two or more stars orbiting each other..
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- 1765 - Quasars take us back in time? The Universe was more dense and chaotic. Astronomers use this to discover an accelerating, expanding universe. Quasars are so luminous astronomers are seeing them at great distances, back in time to the earliest formation of galaxies after the Big Bang. Quasars, are “quasi-stellar objects“, first discovered in 1962. They appear as star-like points with energies that are the most powerful in the Universe.
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- 1381 - V381 - Our Mistaken Quasar. It was the brightest X-ray source in the sky. We thought it was a Quasar. V381 is the brightest, most distant, fastest star found to date. It was first discovered in 1967 using radio telescopes. It was then called a Quasi-Stellar Radio Object, or QUASAR for short. Since then astronomers have identified over 200,000 Quasars, but, all are far distant, billions of lightyears away. With this one exception Quasars appeared to only exist in the early Universe. The Universe is not creating Quasars any more?
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- May 12, 2020 2737
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