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Various "black holes"[1] are simply solutions to the Einstein Field Equations, and, if the EFE are an accurate picture of reality, then "bent time" (nontrivial spacetime curvature tensor) is exactly what the Einstein Field Equations tell us. In particular, the EFE predict a situation where, if there is enough energy in a region of space, then the geometry of ...


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Your thinking about general relativity. Gravity actually changes time and the reason why we know this (other than our equations that tell us it is so) is because we have measured it. Time flows slower on earth than on our satellites. People who design satellites need to change their clocks so that they match up with earth. Even spending your life on a plane ...


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If you put your itty bitty magnet with the 1.4 tesla field at the North Magnetic Pole, and another identical one at the South Magnetic Pole, then you would have added 1.4 tesla at each pole. There would be zero effect on the Earth's magnetic field. Like all fields you're likely to encounter, magnetic field strength depends on the distance from the source. ...


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How strong is Earths magnetic field in space? At what distance? The Earth's magnetic field is roughly modeled as a tilted dipole (i.e., the magnetization axis is tilted with respect to the spin axis of rotation). The magnitude at the magnetic equator is given by the approximation: $$ \lvert \mathbf{B} \rvert \left( r \right) \approx B_{o} \left( \frac{R_{...


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There are four forces that describe matter and energy in the universe. These forces are much stronger than the expansion of space. The raisin bread analogue is also good to understand this: The raisins do not puff up as the bread does, because the electromagnetic cohesive forces of the raisin body maintain its volume since no yeast is working within the ...


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Your intuition is correct. There is no particular reason to assume any given region of space is not expanding, based on present data. However, measuring this on small scales is difficult. If we assume a very simplified version of expansion, we can get a numeric value for the expansion rate: $74.2 \frac{km/s}{MPc}$. Thus, a galaxy 10Mpc away from us would ...


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The gravity of the galaxy$^1$ holds it together; that is what keeps the distance between stars in a galaxy expanding. In other words, the gravitational pull of the galaxy overcomes the antigravity "pull" of the cosmological constant. A good image is that of a couple groups of, say, five people. Each individual group has everyone standing in a circle and ...


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Why does Light-years or Parsecs seem to be the standard rather than SI? In the solar system astronomy, the astronomical unit is much more widely used rather than meters for distance, days (86400 seconds), Julian years (365.25 days), or Julian centuries (36525 days) are used rather than seconds for time, and the solar mass is used rather than kilograms for ...


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SI units are created for everyday life and therefore convenient to use in everyday life. The following sentences makes sense in modern human mind; "I live 300 meters away from here" or "My new boat is 35 meters long" or "I am bust now please call in 5 minutes". Moreover the calculations with these numbers are easy. If you hear someone saying "I drove 50 km ...


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Light years and parsecs have been used since long before SI existed, so a lot of it is tradition. But using light years also makes it very obvious how long the light has traveled to get here, and thus which era of the universe we are seeing the object in. Something that is 11 billion light years away dates from the era of early galaxies, for example. If you ...


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First, I am going to provide a little background on equivalent pressures at different altitudes from Earth's surface. Layers of Earth's Atmosphere Troposphere to Mesosphere At sea level, the neutral atmosphere of Earth has a pressure of ~$10^{5}$ Pa (or ~1000 mbars). The below image from https://en.wikipedia.org/wiki/File:...



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