Thursday, April 6, 2023

3947 - BIG BANG THEORY - how it all got started?

 

-   3947 -   BIG  BANG  THEORY  -    how it all got started?  The Sun and the Earth formed a solar system.  The Milky Way Galaxy is full of “suns”.  And we have discovered at least 5,000 other planets around some of these stars.  We know there are billions of galaxies in the Universe.  How did this all come to be?


------------  3947  -  BIG  BANG  THEORY  -    how it all got started?

-    The Big Bang Theory is the leading explanation for how the universe began. Simply put, it says the universe as we know it started with an infinitely hot and dense single point that inflated and stretched.   First at unimaginable speeds, and then at a more measurable rate over the next 13,700,000,000 years to the still-expanding cosmos that we know today.

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-    Existing technology doesn't yet allow astronomers to literally peer back at the universe's birth, much of what we understand about the Big Bang comes from mathematical formulas and models. Astronomers can, however, see the "echo" of the expansion through a phenomenon known as the “cosmic microwave background”.

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-   Around 13.7 billion years ago, everything in the entire universe was condensed in an infinitesimally small singularity, a point of infinite denseness and heat.

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-  Suddenly, an explosive expansion began, ballooning our universe outwards faster than the speed of light. This was a period of “cosmic inflation” that lasted fractions of a second, about 10^-32 of a second.

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-    When cosmic inflation came to a sudden and still-mysterious end, the more classic descriptions of the Big Bang took hold. A flood of matter and radiation, known as "reheating," began populating our universe with the stuff we know today: particles, atoms, the stuff that would become stars and galaxies and so on.

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-    This all happened within just the first second after the universe began, when the temperature of everything was still insanely hot, at about 10 billion degrees Fahrenheit.   The cosmos now contained a vast array of fundamental particles such as neutrons, electrons and protons which are the raw materials that would become the building blocks for everything that exists today.

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-    This early "soup" would have been impossible to actually see because it couldn't hold visible light. mThe free electrons would have caused light (photons) to scatter the way sunlight scatters from the water droplets in clouds. Over time these free electrons met up with nuclei and created neutral atoms or atoms with equal positive and negative electric charges.

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-    This allowed light to finally shine through, about 380,000 years after the Big Bang.  Sometimes called the "afterglow" of the Big Bang, this light is more properly known as the cosmic microwave background (CMB). It was first predicted by Ralph Alpher and other scientists in 1948 but was found only by accident almost 20 years later.

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-    This accidental discovery happened when Arno Penzias and Robert Wilson, both of Bell Telephone Laboratories in New Jersey, were building a radio receiver in 1965 and picked up higher-than-expected temperatures. At first, they thought the anomaly was due to pigeons trying to roost inside the antenna and their waste, but they cleaned up the mess and killed the pigeons and the anomaly persisted.

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-    Simultaneously, a Princeton University team led by Robert Dicke was trying to find evidence of the CMB and realized that Penzias and Wilson had stumbled upon it with their strange observations. The two groups each published papers in the Astrophysical Journal in 1965.

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-    Researchers investigated the split between matter and antimatter. In the study they proposed that the imbalance in the amount of matter and antimatter in the universe is related to the universe's vast quantities of dark matter, an unknown substance that exerts influence over gravity and yet doesn't interact with light. They suggested that in the crucial moments immediately after the Big Bang, the universe may have been pushed to make more matter than its inverse, antimatter, which then could have led to the formation of dark matter.

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-    The CMB has been observed by many researchers now and with many spacecraft missions. One of the most famous space-faring missions to do so was NASA's Cosmic Background Explorer (COBE) satellite, which mapped the sky in the 1990s.

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-    Several other missions have followed in COBE's footsteps, such as the BOOMERanG experiment (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics), NASA's Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency's Planck satellite.

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-    Planck's observations mapped the CMB in unprecedented detail and revealed that the universe was older than previously thought: 13.82 billion years old, rather than 13.7 billion years old.

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-   The maps give rise to new mysteries, however, such as why the Southern Hemisphere appears slightly redder (warmer) than the Northern Hemisphere. The Big Bang Theory says that the CMB would be mostly the same, no matter where you look.

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-    Examining the CMB also gives astronomers clues as to the composition of the universe. Researchers think most of the cosmos is made up of matter and energy that cannot be "sensed" with our conventional instruments, leading to the names "dark matter" and "dark energy."

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-   It is thought that “only 5% of the universe” is made up of matter such as planets, stars and galaxies, and us.

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-     In the first second after the universe was born, our cosmos ballooned faster than the speed of light. (That does not violate Albert Einstein's speed limit. He once said that light speed is the fastest anything can travel within the universe, but that statement did not apply to the inflation of the universe itself.)

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-    As the universe expanded, it created the CMB and a similar "background noise" made up of gravitational waves that, like the CMB, were a sort of static, detectable from all parts of the sky. Those gravitational waves, according to the LIGO Scientific Collaboration produced a theorized barely-detectable polarization, one type of which is called "B-modes."

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-   These waves, which are not B-modes from the birth of the universe but rather from more recent collisions of black holes, have been detected multiple times by the Laser Interferometer Gravitational-Wave Observatory (LIGO).    As LIGO becomes more sensitive, it is anticipated that discovering black hole-related gravitational waves will be a fairly frequent event.

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-   Although the Big Bang is often described as an "explosion", that's a misleading image. In an explosion, fragments are flung out from a central point into a pre-existing space. If you were at the central point, you'd see all the fragments moving away from you at roughly the same speed.

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-    But the Big Bang wasn't like that. It was an expansion of space itself.  Which is a concept that comes out of Einstein's equations of general relativity but has no counterpart in the classical physics of everyday life.

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-   It means that all the distances in the universe are stretching out at the same rate. Any two galaxies separated by distance X are receding from each other at the same speed, while a galaxy at distance 2X recedes at twice that speed.

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-   The universe is not only expanding, but expanding faster. This means that with time, nobody will be able to spot other galaxies from Earth or any other vantage point within our galaxy.

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-    Eventually, a distant galaxy will reach the speed of light. What that means is that even light won't be able to bridge the gap that's being opened between that galaxy and us. There's no way for extraterrestrials on that galaxy to communicate with us, to send any signals that will reach us, once their galaxy is moving faster than light relative to us.

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-     While we can understand how the universe we see came to be, it's possible that the Big Bang was not the first inflationary period the universe experienced. Some scientists believe we live in a cosmos that goes through regular cycles of inflation and deflation, and that we just happen to be living in one of these phases

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-     A telescope is almost like a time machine, allowing us to peer back into the distant past. With the aid of the Hubble space telescope, NASA has shown us galaxies as they were many billions of years ago,  and, Hubble's successor, the James Webb Space Telescope, has the ability to look even deeper into the past.

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-   NASA hopes it will see all the way back to when the first galaxies formed, nearly 13.6 billion years ago. And unlike Hubble, which sees mainly in the visible waveband, JWST is an infrared telescope which is a big advantage when looking at very distant galaxies.

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-    The expansion of the universe means that waves emitted from them are stretched out, so light that was emitted at visible wavelengths actually reaches us in the infrared.

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                   April 6, 2023       BIG  BANG  THEORY  -    how it all got started?          3947                                                                                                                         

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