- 2988 - REALITY - what is it really? What is Reality and How Do Astronomers Deal with It? Is the Universe 3 dimensional? How did space begin? Why is there matter filling space? How were galaxies born? What is Dark Matter? Is all the matter found in galaxies? What is Dark Energy? Will the Universe expand forever?
-------------------------- 2988 - REALITY - what is it really?
- Reality means there is an external world out there whose properties are definite and independent of the observer who perceives them. However, there is no way to remove the observer from his perceptions.
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- According to the “model-dependent reality” it is pointless to as whether a model is “real”. Ask only does it agree with observation? Whenever we develop a model and we find it successfully matching what we observe we call that “reality”. So be it.
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- Astronomers have 3 major models for the evolution of the Universe, called “Cosmology“, the models include “Dark Energy, Dark Matter“, and “Cosmic Inflation“. Using these models raises some questions.
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---------- Is the Universe limited to 3 dimensions for space?
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----------- Or, 4 dimensions if you add time for spacetime.
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----------- Could more dimensions then these 4 explain why gravity is so much weaker than the other 3 forces.
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- One explanation coming out of String Theory is that an unknown particle called a “graviton” is a force-carrier for gravity. And, the gravitons live in a 5th dimension separate for the 4 that we know about. That is why gravity is so weak. Much it has leaked away into this 5th dimension.
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- However, to get the math to work in String Theory we can not stop a 5 dimensions, we need 11. None of this model is proven in observation. It is just beautiful math at this point in history.
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----------- How did the Universe begin? The Universe came out of a massive “eruption“, a single event, that occurred 13,700,000,000 years ago. A single point of energy expanded, as the expansion cooled matter froze out of the energy creating particles of quarks, gluons, neutrinos, and electrons.
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- When the expansion cooled enough these fundamental particles combined to form protons, neutrons, hadrons, and mesons. When the expansion continued just one second later neutrons, protons, photons, electrons and neutrinos filled the expanding space.
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- Sound waves rippled through this cosmic soup of particles. After 380,000 years of expansion this opaque plasma of particles began releasing photons of light. Electrons and protons cooled enough to begin combining into neutral atoms. This Gamma Ray radiation of photons was 3,000 Kelvin. Today it is 2.7 Kelvin and known as the Cosmic Microwave Background radiation (CMB).
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- In 1970 Alan Guth explained the uniform smoothness of the CMB in all directions and at opposite ends of the Universe. The opposite ends of the Universe could not be in contact because light could not have had time to travel between them. For the opposite ends to be the same temperature they must have one time been in contact with each other.
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- Guth proposed that a “Cosmic Inflation” occurred microseconds after the Big Bang. The expansion for an instant increased the size of the Universe faster than the speed of light. After that brief period of Cosmic Inflation the Universe returned to the slower expansion rate we see today.
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- A possible explanation for the Cosmic Inflation is that the 4 know forces in the Universe were once one single force. Gravity, then Strong and Weak nuclear forces, then the electromagnetic forces broke out of the single force releasing powerful energy to cause the expansion of space.
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- Because the Universe is much, much larger than our Observable Universe the geometry of Space appears “flat” to us.
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-------------- Why does matter fill the Universe? Actually Ordinary Matter is only 5% of the mass-energy that fills the Universe. 95% of the Universe is Dark Matter and Dark Energy. But, even the 5% of Ordinary Matter is a mystery.
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- Because matter created from energy comes in matter and anti-matter pairs. That is how the Conservation of Energy works. But, matter and anti-matter colliding would annihilate creating Gamma Rays back to energy again. Why did some “matter” survive? Theoretically the Universe should be filled with only energy by now. Go figure?
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------------- How did the galaxies form? When the expansion first occurred the sub-atomic particles experienced quantum fluctuations described by the ‘Uncertainty Principle‘. Single points did not exist. Only waves of probabilities can describe these particles. These waves of fluctuations created denser and rarefied areas in the expanding plasma.
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- Gravity worked to concentrated the denser areas even move. Eventually enough mass was condensed by gravity to create the first stars. Gravity continued to work with Dark Matter to condense the stars in to groups called galaxies. 3-dimensional maps of galaxies and bubbles of space and filaments of stars seen today match the quantum fluctuations at the beginning of the Universe.
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---------------- What is cold Dark Matter? Stars and galaxies comprise only 0.5% of the mass-energy in the expanding Universe. Add to that all the hydrogen and helium interstellar gas and you can get to 4% of the mass of the Universe. 23% more is cold Dark Matter. The rest, 73% is Dark Energy. (See Review 2497 to learn more about Dark Matter.)
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------------- Is all the Ordinary Matter found in stars and galaxies? Only 10% of the Ordinary Matter is in the form of stars. Where is the rest of the matter? In could be interstellar dust. But, that is an awful lot of dust that we can not see.
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------------ What is Dark Energy? To make the Universe expand and accelerate in its expansion there must be a balance between the pull of gravity and the push of Dark Energy. For the balance to work 73% of the mass-energy of the Universe must be Dark Energy. “Dark” because we have no idea what it is or what causes it.
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- All we have accomplished so far is to name it. It could be the energy in the vacuum of space itself. What is space, really? Is a vacuum really nothing? We think space is 3 dimensional, but, maybe there are extra dimensions that we do not know about?
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- Dark Energy is not a force because it does not act on particles of mass. It appears to act on space itself. Dark Energy is similar, but much smaller, to the Cosmic Expansion that happened seconds after the Big Bang. But, Cosmic Inflation lasted seconds, Dark Energy has lasted for over 13 billion years.
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- Recording the Universe expansion appears to show that Gravity was dominant for the first 5 billion years, a balance occurred then Dark Energy became dominant for the last 5 billion years. We need a new fundamental theory to explain Dark Energy.
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----------- Will the Universe expand into infinity? It appears that the Universe is not only continuing to expand indefinitely, it is accelerating in its rate of expansion. If it continues, the expansion will pass outside our Observable Universe.
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- The Observable Universe that we will see in 100 billion years from now will only be our immediate local group of galaxies that are gravitationally held together still overpower the push of Dark Energy in the space between our local galaxies.
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- These are only 8 questions that perplex us about our Universe. It becomes a religion of sorts. A faith that we can find the answers if we keep trying. We seem destined to keep trying.
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- It seems to be human nature. We desire to learn who we are, how did we get here, why are we here, where did we come from, how did it all happen , and who is in charge?
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January 20, 2021 REALITY - what is it really? 1214 2988
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--------------------- --- Thursday, January 21, 2021 ---------------------------
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