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------------------- 2555 - FORCES - and densities of the Universe?
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- “Understanding the Forces of the Universe” from 12 half-hour lectures by Dr. Neil deBrasse Tyson, let my know. To understand what’s happening in space exploration today you need a basic understanding of these scientific principles, to follow:
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- Nature’s natural state for things are to be in motion, not at rest, and to be round. Round because a sphere is the geometry of lowest energy. And, energy always tries to get to the lowest level.
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- The energy pulling something together, like gravity, gets the maximum volume with the minimum surface area when it is in the shape of a sphere. Planets, stars, soap bubbles, and the Observable Universe are all spheres.
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- To make a metal ball bearing you drop a bit of molten metal down a long tube. It cools as it falls and when it hits bottom it is a near perfect sphere, a hard ball. Raindrops are spheres, not tear drops.
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- If something is not a sphere than some other force is involved to make it so. Crystals are not spheres because of the electromagnetic forces. Same is true for you. Asteroids are not spheres because they are too small to have enough gravity to pull themselves into a sphere.
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- In the case of asteroids chemical bonds are stronger than the force of gravity. The Earth is a sphere plus or minus 12 miles. That is 12 miles out of an 8,000 mile diameter, or, within 0.15% We can not manufacture a sphere with better smoothness than that.
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- Tidal forces are gravity forces from an external mass. The ocean tides occur because of the difference of gravity force on the close side to the Moon to the far-side of Earth to the Moon.
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- Rotational forces are centripetal forces, which are really the result of the Conservation of Angular Momentum, which is really the result of the Conservation of Energy. As a radius decreases the angular velocity must increase in order to keep momentum constant. The forces of rotation flattens a system into a disk. This is how spiral galaxies form from a sphere to a disk.
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- Neutron Stars are the most perfect spheres. They are the mass of the Sun yet only 10 miles in diameter and spinning at 30 revolutions per second ( 1800 rpm). Extreme density allows them to stay together with extreme gravity pulling to the center. Neutron stars are the densest things we know:
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------------------ 10,000 grams / cm^3 is the density of a Neutron Star
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------------------ 1 gram / cm^3 is the density of water
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----------------- 2 - 5 grams / cm^3 is the density of rock
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----------------- 4 - 15 grams / cm^3 is the density of metals
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---------------- 12 grams / cm^3 is Earth’s core
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-------------------- 3 grams / cm^3 is Earth’s crust
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------------------- 5.5 grams / cm^3 is the average density for Earth.
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- The Sun, us humans, and water are all about the same density, about 1 gram / cm^3. The planet Saturn is less that 1 gram /cm^3 and would float in water, if there was an ocean big enough to hold it.
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- Density varies over a wide range in the Universe. The air at sea level contains 10^18 molecules / cm^3 and weighs 15 pounds per square inch. That is a column of air 1 square inch in area and 75 miles tall. That air weighs 15 pounds. If you go to the top of a 14,000 foot mountain the air weighs 10 pounds.
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- The density of matter in interplanetary space is 10 molecules / cm^3.
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- The density of gas in a comet tail is 10,000 molecules / cm^3.
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- The density of the Sun is 1.4 grams / cm^3. When it expands into a Red Giant 5 billion years from now its density will be only 0.0000014 grams / cm^3
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- The density of interstellar space is 1 atom / 1,000,000 cm^3 , or 1 atom / meter^3.
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- The Critical Density needed for gravity to halt the expansion of the Universe is 10 atoms / meter^3.
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- Empty space has a density of 0 atoms / meters^3. But, here is the theory how vacuum pressure, or Dark Energy, can create the expansion force in the Universe. In this vacuum particle pairs of matter and anti-matter pop in and out of existence. Their creation and annihilation are so fast that they can not be detected, but, they create the pressure in space that expands the universe at an ever increasing rate.
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- Outside our Universe is outside of space. Out there there is not even nothing. The density of nothing is nothing.
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- To escape the gravity of Earth you need a velocity of 25,000 miles per hour. However, you can escape from a comet surface with a velocity of only 2 miles per hour.
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-------------------- To escape from the Moon, 540 mph, or 1.5 miles per second
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-------------------- To escape from the Sun, 144,000 mph, or, 400 mps.
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-------------------- To escape from a Black Hole, 670,000,000 mph, or, 186,000 mps.
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- When the Universe was the size of an atom, 13,700,000,000 years ago Quantum Mechanics and gravity had to be the same. Gravity split off and the Universe expanded by 30 powers of 10.
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- The expanding space was a little lumpy, but not much. It was smooth to within 1 part in 100,000. Somehow there was 1 more particle of matter for every billion pairs of matter, anti-matter.
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- For the first 400,000 years free electrons scattered the light. You could see the surface but you could not see inside the expanding bubble. It was like a white cloud of water vapor. When you see a cloud you see its surface because you can not see inside due to the water molecules scattering the light.
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- The surface we see today of the expanding Universe is the Cosmic Microwave Background radiation. It is the instant when free electrons cooled enough to be captured by free protons and become neutral atoms.
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- The light then left this bubble as Gamma Rays. Since then the Universe has expanded by a factor of 1,000. The Gamma Ray wavelengths have been stretched to Microwave wave lengths. The 3,000 K temperature has cooled to 3 K.
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- The lumps have formed into 100,000,000,000 galaxies, each with about 100,000,000,000 stars. So, in round numbers the Observable Universe contains 10,000,000,000,000,000,000,000 stars in a still lumpy Universe.
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- After 10,000,000 years the largest stars in the early Universe exploded into supernovae. These explosions scattered all the elements in the periodic table into space as interstellar dust.
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- Planets and people evolved from this dust. Life needed energy, liquid water, and complex molecules. The Sun, comets, and space dust provided what was needed.
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- From the Big Bang to you reading about it is the “Greatest Story Ever Told“.
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- December 22, 2019 2555 931
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--------------------- Sunday, December 22, 2019 --------------------
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