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---------------------- 2728 - UNIVERSE - is it the same everywhere?
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- Science's Grand Unifying Theory of Everything is on hold as astronomers are finding hints that one of the cosmological constants is not so constant after all. It may not be the same everywhere in the Universe?
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- New measurements of light emitted from a quasar 13 billion light years away reaffirm past studies that found tiny variations in the “fine structure constant“. (See several available Reviews on the subject of the Fine Structure Constant)
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- The fine structure constant is a measure of electromagnetism. It is one of the four fundamental forces in nature (the others are gravity, weak nuclear force and strong nuclear force). The fine structure constant is the quantity that physicists use as a measure of the strength of the electromagnetic force.
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------------------------------- FSC = e^2 / h * c
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------------------------------ FSC = 1 / 137
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- The Constant a dimensionless number and it involves the speed of light “c“, the Planck's constant “h” and the electron charge “e“, in a mathematical ratio. It is the number that physicists use to measure the strength of the electromagnetic force.
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- The electromagnetic force keeps electrons whizzing around a nucleus in every atom of the universe Without this force, all matter would fly apart. Up until now, it was believed to be an unchanging force throughout time and space. It is the same everywhere in the Universe.
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- But, astronomers have noticed anomalies in the fine structure constant whereby the electromagnetic force measured in one particular direction of the universe seems ever so slightly different than looking in another direction in the universe.
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- The differences seem to not vary as a function of time, but actually in the direction you are looking in the universe.
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- Astronomer were looking at some of the most distant quasars, massive celestial bodies emitting exceptionally high energy, at the edges of the universe. These anomalies were first observed using the world's most powerful telescopes. The quasars were all about 12 to 13 billion light years away.
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- These observation are as the Universe was near the very beginning. Studying the light in detail from these distant quasars, is studying the properties of the universe as it was when it was in its infancy, only a billion years old.
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- The universe then was very, very different. No galaxies existed, the early stars had formed but there was certainly not the same population of stars that we see today. And there were no planets. And definitely no astronomers.
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- Today’s astronomers were studying one quasar when the universe was only a billion years old. Measurements of the fine structure constant were made along this one line of sight to this one quasar.
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- The results resurfaced the question, could there be a directionality in the universe? The universe may not be “isotropic” in its laws of physics, that is the same, statistically, in all directions. But there could be some direction or preferred direction in the universe where the laws of physics change, but not in the perpendicular direction. In other words, the universe in some sense, has a dipole structure to it.
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- In one particular direction, we can look back 12 billion light years and measure electromagnetism when the universe was very young. Putting all the data together, electromagnetism seems to gradually increase the further we look, while towards the opposite direction, it gradually decreases. In other directions in the cosmos, the fine structure constant remains constant.
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- In other words, in what was thought to be an arbitrarily random spread of galaxies, quasars, black holes, stars, gas clouds and planets with life flourishing in at least one tiny part of it. The universe appears to have the equivalent of a north and a south.
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- This is something that is taken very seriously and is regarded, quite correctly with skepticism. But it's something you've got to test because it is possible we live in a different universe. A universe that has some sort of “directionality“.
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- For a long time, it has been thought that the laws of nature appear perfectly tuned to set the conditions for life to flourish. The strength of the electromagnetic force is one of those quantities. If it were only a few percent different to the value we measure on Earth, the chemical evolution of the universe would be completely different and life may never have got going.
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- This raises a tantalizing question: does this "Goldilocks' situation, where fundamental physical quantities like the fine structure constant are 'just right' to favor our existence, apply throughout the entire universe?
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- If there is a directionality in the universe, and if electromagnetism is shown to be very slightly different in certain regions of the cosmos, the most fundamental concepts underpinning much of modern physics will need revision. Our “standard model of cosmology” is based on this isotropic universe, one that is the same, statistically, in all directions.
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- That standard model itself is built upon Einstein's theory of gravity, which itself explicitly assumes constancy of the laws of Nature. If such fundamental principles turn out to be only “good approximations“, the doors are open to some very exciting, new ideas in physics.
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- So now are we living at the center of the universe? Does the whole universe revolve around us? Does this mean that there's something special about where we live?
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- This is a reasonable line of thinking, and it was how modern science got its start. The first astronomers assumed that the Sun, Moon, planets and stars orbited around the Earth. That the Earth was a very special and unique place, distinct from the rest of the universe.
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- As astronomers started puzzling out the nature of the laws of physics, they realized that the Earth wasn't as special as they thought. In fact, the laws of nature that govern the forces on Earth are the same everywhere in the universe.
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- As Isaac Newton untangled the laws of gravity here on Earth, he realized it must be the same forces that caused the moon to go around the Earth, and the planets to go around the Sun. That the light from the Sun is the same phenomenon as the light from other stars.
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- When astronomers consider the universe at the largest scales, they have always assumed that it's homogeneous, and isotropic.
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- The universe is homogeneous means that observers in any part of the universe will see roughly the same view as observers in any other part. There might be local differences. At the smallest scales, they'll be different. But as you move to larger and larger scales, it's all just planets, stars, galaxies, galaxy clusters and black holes.
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- Isotropic means that the universe looks the same in every direction. The observable universe, the galaxies, galaxy clusters and eventually the cosmic microwave background radiation in all directions looks the same.
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- This is known as the ”cosmological principle“, and it's one of the foundations of astronomy. If the universe wasn't homogeneous and isotropic, then it would mean that the physical laws as we understand them are impossible to comprehend. Just over the cosmological horizon, the force of gravity might act in reverse, the speed of light might be slower than walking speed.
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- However, our current observations, at least to a sphere 13.8 billion light years around us in all directions, confirm this cosmological principle..
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- While we don't live in a special place in the universe, we do live in a special time in the universe. In the distant future, billions or even trillions of years from now, galaxies will be flying away from us so quickly that their light will never reach us.
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- The cosmic background microwave radiation will be redshifted so far that it's completely undetectable Future astronomers will have no idea that there was ever a greater cosmology beyond the Milky Way itself. The evidence of the Big Bang and the ongoing expansion of the universe will be lost forever.
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- If we didn't happen to live when we do now, within billions of years of the beginning of the universe, we'd never know the truth.
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- We can't feel special about our place in the universe if it's probably the same wherever you go. But we can feel special about our time in the universe. Future astronomers will never understand the cosmology and history of the cosmos the way we do now after reading this Review.
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- In that sense, you are special.
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- May 2, 2020 2728
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--------------------- Saturday, May 2, 2020 -------------------------
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