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Showing content with the highest reputation on 11/10/18 in all areas

  1. Please refer to my very recent reply to studiot
    3 points
  2. Remember a time when robots were bound by three laws? Skynet remembers.
    1 point
  3. The counterexample is the integers. That is not a well ordering but each element has a unique successor. IMO this thread has veered off course in the sense that discussing the definition of a well-order, or the mysterious properties of the rationals inside the reals, doesn't really help us understand the Cantor set. But clearly everyone else is happy so I'll stay out of it.
    1 point
  4. Incorrect. g ( gravitational force) is zero at the center, but the Specific(per unit mass) Gravitational potential is -3GM/2R where M is the mass of the planet, and R is its radius. At the surface of the planet (or any point above it) the Specific Gravitational potential is -GM/r where r is the distance from the center of the planet ( on the surface r=R) Yes, agreed. Got it now, thanks.
    1 point
  5. It's indeed wrong, but I couldn't see a refutation in the thread. Classically (i.e. if heat was not subject to gravity), if you have a tall column of gas in a vertical gravitational field at equilibrium, the temperature of the gas is constant while its density (and pressure) decreases with height. Otherwise you could run a small perpetual motion machine using the difference in temperature.
    1 point
  6. Incorrect. g ( gravitational force) is zero at the center, but the Specific(per unit mass) Gravitational potential is -3GM/2R where M is the mass of the planet, and R is its radius. At the surface of the planet (or any point above it) the Specific Gravitational potential is -GM/r where r is the distance from the center of the planet ( on the surface r=R) Specific Gravitational Potential Energy tells us how much energy it would take to move a unit mass from one point in the field to another. It takes energy to lift a mass from the center of the Earth to the surface, just like it takes energy to lift the same unit mass from the surface of the Earth to a point above it. It is the difference in potential gravitational energy is responsible for gravitational time dilation, not the difference in g. An easy way to demonstrate this is to calculate the gravitational time dilation factor for the surface of the Earth vs the surface of a planet with twice the radius and 4 times the mass of the Earth. You will get two different answers even though the value of g will be the same at the surface of both planets. A clock at the center of the Earth is at a lower potential than one on the surface and thus will run slower than one on the surface, even though it feels 0g compared to the surface clock at 1g.
    1 point
  7. Even if this were true, (which it isn't due to the vast difference between Sagittarius A and the galaxy as a whole. Remove Sag A, and the galaxy would hardly notice it), your claim of a difference in weight for objects on the leading and trailing sides of the Earth is wrong. In this statement: The key phrase is "abruptly starts going fast". You feel pulled back due to the fact that the car is changing velocity in that direction. Once you reach speed, you no longer feel that pull. The Earth, is not abruptly changing is velocity in the direction it is traveling around the galaxy, it maintains a pretty constant pace. The only acceleration is has with respect to the galaxy center is towards the center. ( if you want to use the car example, it would like when you feel pushed to the side when you go around a sharp corner at speed.) But even then, the magnitude of that acceleration depends not only on the velocity, but the degree of "bend" in the curve. Even with the high speed that the solar system travels with respect to the center of the galaxy, the curve is so gentle, that the acceleration only works out to 0.000000000018 g (For a 175 lb person, this would result in a difference of 0.000000005 ounces). And even then, the other key word is "orbiting" Objects in orbit are in a free fall path. they may be accelerating but all parts are accelerating equally in response to gravity, so they feel no net difference between their individual parts ( other than that due to the early mentioned tidal force). So even that small acceleration in the above paragraph isn't felt. ( a falling elevator is constantly accelerating downward, but someone in it would not be pined against the ceiling, but would just float around like they were weightless)
    1 point
  8. I have some more (hopefully helpful) thoughts about this post but meanwhile can you say what is in conflict with this presentation of a light clock? No bastard triangles are needed. I did ask if you are applying your analysis to the wrong thing and I ask again as you did not answer. The point is that we should be comparing the second (unit of time) as measured by each observer, as each will observe a different number of units, but it is the relative length of those units that is being transformed (dilated). So to A, B's units will appear dilated (longer) so the square root factor being less than 1 is on the bottom of the fraction in the transformation from his units to B's. This is the usual formula. However when A considers the transformation from B's units to his the square root factor will appear on the top (Einsteins formula) as he need to shorten B's apparently longer units to match his own.
    1 point
  9. If you take having a university degree as a proxy for "intelligence" and you consider the two sides of the debate on the UK leaving the EU as "political factions". (both of which are very much debatable) then yes. http://www.theweek.co.uk/89378/fact-check-did-uk-s-better-educated-vote-remain But it's not clear to what extent "having a degree" is actually just a proxy for "being young".
    1 point
  10. I was thinking about all the vaccine shots one typically has throughout ones life; its quite a few. I've fairly recently had a pneumonia shot and flu shot and it won't end there. I think, ultimately, vaccines are the price we have to pay for living in such large groups.
    1 point
  11. I am not sure what in your point is? I already went over the whole article for you qoutinng full portions in order. I think that is more than enough. What you have highlighted isn't in full context or point of the article. The article has out lived it's usefulness. My initial point was centered around the Demographical breakdown and I referenced more than just the one article. I honestly don't know what you are attempting to dispute. The way Men, Women, Whites, Blacks, and Latinos voted is nearly indentical. That is indisputable and what I posted the numbers to show. Those broad strokes are incredibly consistent and that is undeniable. While Trump continues to brag about the Senate and some Progressive lament that things didn't go better I think it is working noting that Democratic candidates won more support across board in every type of race Tuesday night be it House, Senate, or Governors mansion.
    0 points
  12. Your opinion sucks, quite frankly. Conservatism is absolutely necessary just the way every other tool in our box of democracy is absolutely necessary. What are you, a hammer-only carpenter? I really hate it when People self-inflict limitations, since they vote to do it to us all.
    -1 points
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