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Everything posted by Janus

  1. 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.
  2. 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 d
  3. 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 am
  4. 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)
  5. 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
  6. 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.
  7. First amendment of the US constitution: Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances. So the "right of Freedom of speech" pertains to the limits the US government has in this manner. It does not matter if the term "freedom of speech" already existed or who first coined it.
  8. The period over which tidal locking would occur is highly sensitive to the distance between the bodies, and varies by the distance to the power of 6. It is less dependent on the mass of the primary. The relationship ( assuming all else is equal) is T = a^6/M^2 So, if we take a very luminous red dwarf like Lacaille 8760 with a mass of 0.6 that of the Sun, and a Earth equivalent position in the habitable zone of 0.268AU, you get a time period for tidal locking of roughly 1/1000 of the the time it would take for the Earth to tidal lock to the Sun. For a smaller star like Proxima Cen
  9. That was the argument put forth by Galileo against the Aristotelian model of gravity that posited that heavier objects fell faster than lighter ones. It was not meant an argument against gravity itself, but against that particular model. He wasn't saying that gravity didn't exist, but that it didn't behave like Aristotle said it did. The model for gravity that replaced the old one didn't suffer from this feature.
  10. Of course no mention of the fact that if Mars had been at geostationary orbit distance from the Earth it would have pulled all the Earth's oceans into 6 km high tidal bulges.
  11. Growing up, we had a Siamese cat which had quite a reputation (It once chased a dog several times it size off our property.) Some people got to the point, that when they came over the first thing they would do was look around nervously and ask "Where's the cat"? And we had to warn people that if the cat came around don't reach down to pet her or your likely to pull your hand back bloodied. Now he wasn't that way with anyone in our household. (There were times when the cat would get under Mom's feet in the kitchen and she'd just pick her up with one hand and toss her out, and cat did no
  12. Right after I retired, I started taking morning walks for the exercise. My wife usually would join me, but a few weeks in she tweaked her back and couldn't, so I took my walks solo for a while. We had a cat at the time. Every day, when I got back from my morning walk, he come running, meowing, jump up onto the back of the sofa (which was near the front door), And wait for me to put my head down so he could give me a head bump. Then he'd jump down and go about his business. He'd already been fed, and my wife always fed him anyway, and It wasn't as if he had been lonely, as she had been
  13. My paternal Grandfather was 6 when the Civil war started (Born in Dec of 1854), though he didn't come to the US until 1883.
  14. You could set things up so that, from a given frame, the clocks started and ended "in sync", but this would require artificially adjusting the tick rate of the clocks. Thus you could get this as measured from the rest frame of the lower row of clocks. All the clocks in both rows remain in sync. However, when you transition to the rest frame of the upper row of clocks, you get this: The only moment when any two clocks read the same is when they are passing each other.
  15. Just after Thanksgiving, I finally updated my 7+ year old computer to a new "gaming"* computer. This has allowed me to upgrade Blender to the latest build, which has a number of new features and tools, as well as driving the render times down significantly. For example. One of the Star Trek matte paintings I tried to duplicate with Blender was of Stratos, the cloud city. While modeling the buildings wasn't that difficult, the clouds became problematic. In order to get the right look, you had to create a light scattering volume. This means that the render engine has to take into a
  16. There is a formula for this, it is the same one used to find synodic periods for planets etc. (for example, how long it takes between Earth and Mars passing each other as they orbit the Sun.) The formula is T = 1/(1/p1-1/p2) Where p1 id the time it takes for one plane to complete is orbit and p2 is the time for the other planet to complete is orbit. In this case we are not given times, so we will simply give B a complete circuit walking time of 1 time unit and thus A has a complete circuit walking time of 1/2 time unit. Thus for when they are walking in the same direction
  17. As swansot has already mentioned, it isn't quite that simple. There will be a gradient. Not only that, but there is the fact that the air in your ship will already be under pressure. If it is at 1 atm, this pressure is the same as caused by the weight of a column of air at constant sea level density which is 8.5 km tall.( at 1 g of gravity). So let's say your spaceship is 10 meters long and full of air at 1 atm. If you were to accelerate at 850 g, that air would be "pushed back" towards the rear of the ship. That 10 m column at 850g would act like a 8.5 km tall column at 1g. The
  18. Reminds me of the time when I was a kid in Northern Minn. My Dad was driving to work in the early AM. He began to feel cold, even though the car heater was going full blast, and was starting to wonder what had gone wrong with it, when the weather report came over the radio announcing that the present temperature in the small town he was passing through at the time was -50° F
  19. Maybe we should check between the sofa cushions.
  20. It's the second case. Elements that aren't stable, but relatively more stable than you would expect for such a heavy element.
  21. Janus

    Political Humor

    On the same topic: A reporter in a recent press conference asked whether Biden would hang a portrait of Trump in the White House ( something Trump refused to do for Obama) and along the same lines would he be inviting Obama to ceremony to finally hang his portrait. The answer was that no portraits hangings had been scheduled yet. But it struck me as a bit of a silly question. With everything on his plate right now, I doubt that Biden is giving much thought (or should be) to such purely ceremonial things.
  22. On the other hand, there are a number of past members of former Republican administrations that have begun to discuss forming an Anti-Trump party over their dissatisfaction over how the present Republican establishment have been too subservient to Trump. The party could be bleeding voters from both ends.
  23. I would put into consideration a different contribution made by Hubble prior to his Law. In 1924 he discovered Cepheid variable stars in Andromeda, which he was able to use to show that Andromeda was far outside our own galaxy, and not a part of it. While there had been debate about this., his observations were the first to provide exidence that the cosmos was much more vast than previously suspected and extended well beyond the Milky way.
  24. Just to build on what has already been said. "Everything" is not moving away from each other. The atoms making up the Earth aren't, The planets are not moving away from the Sun (or at least not due to reasons tied to universal expansion), the stars in the galaxy aren't flying apart... All these structures are held together by interactions that are much stronger than universal expansion.* Our galaxy, along with Andromeda and a few others are part of a local group bound together by mutual gravitation. Our local group is one of many in a larger cluster. You have to go to scales beyond
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