- 3090 - TIME - GPS, and Entropy? The rate that time flows is not a constant like the rate of speed of the electromagnetic energy, (i.e. the speed of light) or the force of gravity, or the mass of every electron. Light, gravity, and electron mass are “constant“, time is “variable“. The fact that time flows at different rates is not something that we encounter in our everyday lives
----------------- 3090 - TIME - GPS, and Entropy
- A gravitational field will retard ,or slow down, the passage of time. Therefore, there are different rates of time flowing at different altitudes above Earth and on different planets in the Solar System. Clocks on the Moon tick faster than those at Mission Control in Houston, Texas. Also, clocks on GPS satellites tick faster.
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- Rapid motion will retard, or slow down, the passage of time. If you were traveling 87% of the speed of light time would appear to have slowed to half its normal rate. Again this is not something we encounter in our everyday lives. However, space travel and technology is beginning to bring these differences to us. This speed in orbit has to be compensated in GPS clocks running slower. (That is also in another review on GPS that is available)
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- Astronauts are aging more slowly than the rest of us. Yes, the experience of less gravity makes their time run faster than it does for us on the surface of Earth. In a lower gravity the rate of time’s flow is faster.
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- However, to stay in that lower gravity orbit astronauts must be traveling at the escape velocity in order to be in orbit. They are traveling at 1/26,000 the speed of light, 4 hundredths of a percent of the speed of light. But, that rapid motion slows down the rate of time. At a few hundred miles altitude and traveling 25,000 miles per hour the speed wins out and the net affect is that astronauts age more slowly.
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- Astronauts would have to orbit Earth at an altitude of 2,000 miles for lesser gravity and slower orbital speed to average out and then they would age at the same rate as we do on the surface of Earth.
- Yes, these changes are small, but we are beginning to reach the technology where if we do not take these variations of time into account the technology does not work properly. Take for example the Global Positioning System, GPS.
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- This system of satellites measures distances quite accurately by measuring the time it takes for a radio signal to reach the receivers in other satellites and receivers on the ground. Simple triangulation and geometry is used to calculate a position when the distances are accurately known.
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- The speed of the radio signal is constant, 670,633,500 miles per hour. But, the rate of time is not constant and all of these mathematical compensations must be used for the GPS to give us accurate positions:
--------------- GPS compensates for the satellite’s speed in orbit which slows down the rate of time. Traveling at 17,000 miles per hour for 10 days will causes the clocks to be slow by 300 microseconds relative to those on the ground. If no compensation is used the GPS positions would be 55 miles off target.
-------------- GPS compensates for the lower gravity field in orbit which speeds up the rate of time.
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---------------- GPS compensates for the elevation of the receivers on Earth. Denver’s times is moving faster than San Francisco’s time because at 1 mile elevation its clocks are running faster.
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--------------- GPS compensates for the difference in the rotation speed of varies latitudes on the surface of Earth. The equator is traveling 1,000 miles per hour faster than the poles. Time runs slower for people on the equator.
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------------- GPS compensates for the satellites changes in speed in its elliptical orbits. Satellites speed up at low point is their orbits and slow down at higher point in their orbits in order to maintain a constant energy of angular momentum. Time runs slower when the satellites are speeding up and faster when they are slowing down.
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- All of these changes in the rate time passes must be accounted for accurately and continuously in order for the GPS system to work properly. Here we are dealing with microseconds in difference, but there are places in the Cosmos where a million years pass by while a single second simultaneously elapsed here on Earth. Wow!
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- All of the physical laws appear to scientists to be time symmetrical except one. Physical laws seem to work as well backward and forward in time. The only exception shows up in thermodynamics.
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- The second law in thermodynamics is that “Entropy” in a system always increases, it never decreases. Therefore, Entropy it is not symmetrical with time, it only moves in one direction.
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- The law of Entropy says that all systems tend to move towards disorder, or randomness. Only by adding energy from external to the system can you reverse this process and get order, structure, and complexity from disorder.
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- The ice cube in a glass of water will always melt if left alone. The crystalline structure of the ice will flow to the disorder of the atoms in the liquid water. Never the reverse, unless you add energy from external to the system.
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- We only get order when energy is added. And, we owe all the order and complexity on Earth to the energy added to our system by the Sun.
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- Complex life forms and modern technology do not contradict the law of Entropy. All of our order comes from the Sun. The Sun-Earth system increases Entropy, increases disorder, because the Sun looses mass and structure in the process of supplying us the energy.
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- Scientists tend to think that the direction of time is somehow tied to the direction of increased Entropy. The arrows of both Entropy and time flow in one direction. These too may be tied to the expanding Universe.
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- It looks like the ultimate fate of the Universe is total randomness of mass and energy. Entropy wins out in the end.
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March 12, 2021 TIME - GPS, and Entropy? 854 3079
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--------------------- --- Sunday, March 14, 2021 ---------------------------
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