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-------------------------- 2449 - STRANGE UNIVERSE - expanding forever?
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- If I would have known I was going to live this long I would have taken better care of myself. My education has been neglected and I am still trying to understand the strangeness of the universe? My expanding knowledge can not keep up with the expanding universe.
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- The current accepted estimate for the age of the universe is 13.8 billion years. Our galaxy, the Milky way, 13.5 billion years. The Sun, 4.6 billion years. Planet Earth, 4.5 billion years. Cosmic time scales are hard to make sense of. My 78 years is not even a blip on the screen.
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- The distances does not make it any easier either. The moon is the closest to Earth, 240,000 miles away. In other words, 1.282 light seconds away. The moon we see, is always around 1 second in the past. That is only a slight distortion. The further you look the more distorted it gets. .
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- The farthest galaxy observed is 13.4 billion lightyears from Earth. It is really not that many light years away. Instead, it is probably more than 30 billion light years away now due to the accelerating expansion of the universe. The galaxy we see is as it was 400 million years after the Big bang. The light has been traveling for 13 billion years to reach us. Everything we see in the sky, is the past.
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- Our Milky Way galaxy is part of the 100 to 200 billion galaxies that we estimate exist in the “observable universe“. There are definitely parts of the universe that have expanded away from us and the light has not had enough time to reach us.
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- All the matter that we do see, and all those galaxies, make up only 5 percent of the universe. We do not know what the other 95 percent of it is! If that is not strange enough you do not understand the situation.
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- According to Newton, gravity weakens as you go further from the center and the object moves slower. Stronger the pull, faster the movement. We see this in our solar system. This is why Mercury takes 87 days to go around the sun once while Neptune takes 165 years.
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- Unlike our Solar System stars at edge of galaxies rotate just as fast as the ones near the center. What we see is not obeying the laws of Newton. There is not nearly enough mass in the galaxies to cause this effect so astronomers came to the conclusion that there was something massive causing the gravitational field to extend and keep the stars moving just as fast.
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- Something we can not see so we call it “dark matter“. Dark Matter makes up 25% of the universe.
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- We can’t see it but we can measure its effects. It only interacts gravitationally. And so, some theories suggest maybe we don’t understand gravity and dark matter is not really there.
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- Astronomers measure the behavior of galaxies and the motion of the stars and we conclude we are missing something. We have found the Dragonfly 44 galaxy to have 99 percent dark matter. We have also found another galaxy with no dark matter in it. The fascinating thing is that the galaxy with no dark matter strengthens the case that dark matter exists, but, still remains a mystery.
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- The universe has been expanding since it all began but how does it end? Knowing the amount of matter and its gravity and the rate at which parts of the universe are expanding, we can answer this question. In a sense, it’s a fight between the expansion of the space and gravity of the matter in it. And , expansion wins.
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- There is not enough matter in the universe for the gravity to reverse the expansion. So it will go on forever. We had assumed that at some point, this expansion would slow down and stop. When it was actually measured though, it was shocking to see that the expansion was actually speeding up.
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- This is strange because there doesn’t seem to be a reason for this to be happening. If space was expanding at a constant rate, it would be the opposite of what we expected. But, something was making it go faster than it was in the past.
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- The cause of this accelerating expansion has come to be called dark energy. Other than knowing that it must be a property of empty space itself, we don’t know too much about it.
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- It makes up 70 percent of the universe. The biggest part of it. And as it stands it will continue to grow exponentially. Which means in a distant future everything will be spread out so much there will only be left a dark universe.
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- We know a lot about our world but the majority of it is still unknown to us. Words fail when you try to express how big the universe is. It came in to being and almost 14 billion years later, we showed up. Our existence may be just an accident. Irrelevant in the grand scheme of things.
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- We might not be around forever to witness the end of our planet or the death of the Sun. But we are here now to try to explain how strange it is. Everything remains intact for us to look up and wonder, where did it all come from?
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- Solving the unanswered questions in science may or may not lead to a deeper understanding of the precise nature of “reality“. If it is a good answer, it should lead to more questions. The kind of which we never even thought to ask. We may never really find out everything. But that has never stopped us from trying.
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- Searching for knowledge is like picking up little pebbles on the beach with the whole ocean of the unknown out in front of us. If you want to search more here are some other Reviews about the universe:
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- 2447 - UNIVERSE - how did it all happen? 13.8 billion years ago the universe started as the Big Bang when space itself rapidly began expanding. At the time the observable universe, which included enough materials to build at least 2 trillion galaxies, fit into a space less than a centimeter across. Today the observable universe is 93 billion light-years across and still expanding.
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- 2439 - UNIVERSE - discovering the expansion? One of the biggest scientific surprises in astronomy was the recent discovery that space itself is expanding. And, expanding the Universe at an ever increase rate. Distant galaxies recede from us and from one another more quickly than the nearby ones, as though the fabric of space itself is being stretched by some dark form of energy.
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- 2432 - UNIVERSE - expanding space. If you were born when the Universe was ten times its current age, our local group of galaxies would merge into one and would be the only galaxy you could see in the Universe for trillions of light years.
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- - 2419 - and - 2393 - Age of the Universe
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- 2412 - Comprehending the expanding Universe.
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- 2394 - Wrap your mind around the Universe.
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- 2348 - The Universe from start to finish. 13 pages.
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- 2347 - The Island Universe
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- 2335 - The Universe almost did not happen.
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- 2334 - How is it expanding?
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- 2262 - How fast is it expanding? List 21 more reviews about the Universe.
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- These Reviews are available upon request to learn more.
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- October 5, 2019 2449
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--------------------- Saturday, October 5, 2019 --------------------
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