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Janus

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Janus last won the day on September 28

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  1. While a Moon's tidal influence can dominate, the star will have a tidal influence. For example. Let's start with a planet-moon system tidally locked to each other, The star will still will still produce tidal effects that will produce drag on the Planet's rotation. If this were allowed to happen, then the Moon would orbit faster than the planet rotates. In this situation, the Moon would spiral in, transferring rotational energy to the planet, speeding up its rotation. So what happens is while the Moon does end up keeping the planet tidally locked to itself, it does so at the expense of it's own orbital energy. Both it's orbital period and the rotational period of the planet shorten. However, this can't be maintained forever, as eventually the moon would spiral inside the Roche limit and break up. How long this would take depends on the tidal influence of the star. For example, Proxima Centauri B orbits so close to its star that the stellar tidal forces on it are roughly 1000 times that of the Sun on the Earth.
  2. Magnetic fields have polarity. You have a North and South pole. Like poles repel each other and unlike poles attract. The poles always occur in pairs (a magnet will always have both North and South poles) Because of this, it is possible to arrange the poles in such a way that all the poles cancel each other out and you get no net attraction or repulsion. Gravitational fields have no polarity. They are purely attractive; mass attracts mass. The more mass, the greater the attraction. There is no way to arrange things to get a repulsion or cancellation. But, compared to magnetic fields, gravity is very weak, and it take a considerable amount of mass for this attraction to be easily measured. But, as swansont has already noted, we have measured gravitational attraction between relatively small masses. The earliest such measurement was done by Henry Cavendish in 1797. He took two brass* spheres which were placed on the ends of a long rod which, in turn, was hung from a piano wire at its midpoint. Two more larger Brass spheres were placed near the suspended spheres so that any attraction between them would rotate the rod and twist the piano wire. Then, by measuring how much rod rotated, and knowing how much torque it would take to twist the wire by that amount, he could work out just how much force was attracting the spheres to each other. And since he also knew the mass of the spheres, he was able to derive the constant of proportionality for gravity. This, in turn allowed him to work out the mass of the Earth. Up until then, while we could measure how much gravitational force there was between the Earth and an object of a known mass, and we knew how far the object was from the center of the Earth, we were still left with two unknowns: the mass of the Earth, and the gravitational constant of proportionality. Knowing either one would allow us to work out the other. Cavendish's experiment gave us the value of the gravitational constant, which meant he could now calculate the Earth's mass. Because of this, Cavendish has been referred to as "The man who weighed the Earth". *he used brass as it had no magnetic properties that could have skewed the results.
  3. When we say that gravity has an effect on time, it is important to understand, that is a difference in gravitational potential that is important and not any difference in local gravity strength. A clock at the top a mountain runs faster than one at sea level because it is higher in the gravity well of the Earth, not because gravity is a bit weaker there. If fact, if gravity didn't decrease with altitude, and remained the same at the mountain top as at sea level, not only would the mountain clock still run faster, but the difference between its tick rate and the sea level clock would be even larger. This is despite the fact that both clocks would experience exactly the same magnitude of gravity.
  4. I'm going to focus on this, Others have already explained that you would see the both the Moon and smaller Sun as they were ~8 min prior to the moment you see them. But, just because you "see" them that way, doesn't mean they are in a "different time-frame" from you. So, for example, if the Moon has large clock face on it, and you, from your position, see it reading 11:52, while your clock reads 12:00, you can't conclude that is is 11.52 on the Moon when your clock reads 12:00. The Moon clock ticked off 8 min in the time the light reflected off it left. So, When you see it read 11:52, it actually reads 12:00 just like your own clock. The reason I bring this up is that you mentioned Relativity, and many people get confused about this. They think time dilation etc, is all just related to what we visually see. This is not however the case. In Relativity, we factor out any time difference caused by the time it took the light to travel the intervening distance, and are only concerned with what is left over after that. With your Moon example, we, for the sake of making it simple, assume that the Moon is not moving relative to you, and are ignoring any effects caused by gravity. In this case, there is no net time difference between you and the Moon ( even though the image you see of the Moon is ~8 min delayed)
  5. I've seen a few YouTube videos discussing its release. It seems that the PC requirements for installing it are quite stringent. Only pretty recent CPUs are compatible. (Microsoft has release an "approved CPU" list). MS had also put out a "Health Checker" do you could see if your PC was up to the task, But the backlash from it telling so many people that their PC couldn't run Windows 11 caused them to pull it. Out of curiosity, I checked my CPU against the approved list, and it was on it (my PC is less than a year old), But like @StringJunky, I'll think I'll wait and see.
  6. This is what the Moon as a mirror would look like viewed from the Earth with a telescope. That small bluish dot in the center is the Earth's reflection.
  7. Hal Clement wrote a short story dealing with telepathic aliens communicating with Human. The basic outline was a spaceship containing renegades from their own race, has to do a forced landing on Earth. They are a telepathic race. They land in a remote place where they contact a single human, and they spend a good time learning how to read and interact with his mind. (The idea being that once they learn to do this they can use it to control all humans. And their plans were not good. Once they succeed with this one person, they try and implement their plan, only to have it fail. The problem was, that Humans, not being a naturally telepathic race, had thought patterns that varied from individual to individual. The mental link they had formed with the one human didn't translate into forming it with any others.
  8. Since a TASER doesn't use the Earth ground as part of its circuit, touching a metal pole while being hit by one will make no difference. If the TASER hits the pole: For one thing, the darts won't stick and would glance off, and even if they stuck, the circuit would be completed through the pole and not the person touching it, so they would not be effected by it.
  9. Your last fact is open to what definition of "day" you use. You are using the sidereal day or the rotation relative to the stars. However, the usual use of "day" refers to the Solar day which is the time it takes for the Sun to go from noon to noon. Since Venus' rotation is retrograde (its rotates in the opposite direction to that it orbits the Sun, it's Solar day is only 116 day, 18 hours long.
  10. The disparity between the clocks at any given moment fully depends on the the Frame of reference from which it is being measured. There is no "universal, actual" disparity. The importance of bringing the clocks back together is that this produces a situation where all reference frames agree on the exact amount of disparity between the clocks. In other words, all frames agree that the clocks read the same when initially separated, and all frames agree on the difference between the clocks when reunited, but they will not all agree as to how the difference between the clocks accumulated during the period between those two events.
  11. I just recently saw a video where someone examined an "experiment" done by FE proponents, Dealing with looking across a large body of water at a building. They worked out how much of the building "should" be hidden by the curve, and then pointed out that more of the building was seen than predicted by there being curvature. The examiner pointed out two things: 1. They failed to take into account refraction( as mentioned in earlier posts). 2. The ground floor of the building was not itself at water level, but several yards above it. Once these were taken into account, the amount of building they saw matched the predicted curvature. But the other more interesting thing he pointed out was that, In their own video, some of the building was hidden below the horizon. With a flat Earth, all the building should have been visible. They never even address this and sweep it under the rug. This is typical of the type of intellectual dishonesty they indulge in. Some of the other stuff I've seen makes me me wonder if they just competing to be the poster child for the Dunning-Kruger effect.
  12. By what experiment? Keep in mind that this statement refers to the speed of light in a vacuum ( and not while traveling in a medium), and measured locally ( not its coordinate speed)
  13. Sorry, that makes no sense. In a chemical explosion, the energy comes from the rearrangement of the molecular bonds. The difference in bond energies between the starting and resulting compounds is expressed as an increase of kinetic energy of the resulting compounds. These bonds involve the outer electrons of the atoms E=mc^2 would only come in if you were to very carefully measure the mass of the bomb before detonating, and were able to contain all of the resulting bomb material, let it cool back to the initial bomb's temp and then measure it ( and only it). Then you would notice a very, very slight decrease in mass. For acetylene, the difference works out to be in the range of 1 x 10^10 grams per gram you started with. E= mc^2 tells you how much energy you can get if all of m is converted to energy. But with chemical explosions, m( the mass converted to energy) is minuscule compared to M, (the total mass of the explosive) It is so small, that it is, for all practical purposes, immeasurable. You need a nuclear reaction, dealing with the bonds holding the nucleus itself together to get measurable changes between before and after masses.
  14. Antimony density as a solid: 6.697 g/cm^3. As a liquid: 6.53 g/cm^3. Another way of expressing this is that 1g would have a volume of 0.15314 cc as a liquid, and 0.149320 cc as a solid. Since the mass would remain the same while going from liquid to solid, it would take up less volume after doing so. Bismuth, as a solid has a density of 9.78g/cm^3 as a solid, and 10.05g/cm^3 as a liquid. It's density goes down going from liquid to solid, and this its volume per unit mass goes up.
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