Jump to content

Genady

Senior Members
  • Posts

    5447
  • Joined

  • Days Won

    53

Everything posted by Genady

  1. This short article sheds more light on the OP question: OpenAI's ChatGPT Powered by Human Contractors Paid $15 Per Hour (gizmodo.com)
  2. Black holes are no more vacuums than the Sun, the Earth, any gravitating body. Their gravity is not different from other bodies. They are just more compact.
  3. Yes. No, because this ratio affects phenomena other than EM radiation.
  4. Let's start from the top of the tower. The longest the top plank can stick out without falling is 0.5m: In this case, x = 1.5m. Obviously, it can be made longer using more planks ...
  5. Aren't they just unit conversion constants? c is not a function of those values, but it can be calculated knowing those values. And, at the end of the day, c is just a unit conversion constant as well, the conversion between units of distance and time. All of these constants can, and are, set to 1 in appropriate units.
  6. The gravitational field, like other fields, assumes a configuration that makes a function called action, stationary: the principle of stationary, or least, action. Given the source of the field located somewhere and vacuum everywhere else, it assumes a specific curved shape whose action is stationary.
  7. You're welcome. I agree, and I also agree with your comments above regarding it.
  8. Spacetime is an arrangement of events. The structure and dynamics of the arrangement are determined by the events. The arrangement is quantitatively described as geometry, and the events are quantitatively described as distribution of energy, momenta, and their various derivatives.
  9. But you cannot do this, because you would be counting the same regions multiple times. Newton Shell Theorem is correct and valid in all cases. It is just that when we apply it to an infinite distribution of masses it gives a conditionally converging integral, and this leads to an undefined answer. The outcome of the homogeneously collapsing universe is fully symmetrical: each point is a center of the collapse in the same way as in expanding universe each point is a center of the expansion.
  10. I think this is it. The first 12 minutes is all we need to discuss. Lecture 6: The Dynamics of Homogeneous Expansion, Part II | The Early Universe | Physics | MIT OpenCourseWare
  11. No, it's not it. It just plain old Newtonian gravity.
  12. I also don't believe Allen Guth claimed Newtons Shell theorem as being incorrect. More likely he added some detail or scenario. If you can find the link we can examine it. It is a bit more subtle than this. First I saw this explanation in one of the Susskind lectures, but it will be easier for me to find the Guth's one. I will be happy to discuss it.
  13. This is incorrect. I remember us discussing it about a year ago. I gave you then a link to Alan Guth's MIT lecture where he shows that this is incorrect.
  14. In the observable universe. Diluted by the distances and by the redshift. So, the emission and absorption might be in balance.
  15. Yes, but not only. Massless particles are affected by gravity too. They also produce gravity through pressure. Also, massive particles produce gravity not only by their mass but also by pressure and stress, if these are present. These gravity particles of course are not known currently, but if they are hypothesized, this issue might not exist: a proton you mentioned not only emits particles to interact with everything else, but also absorbs particles emitted by everything else which interacts with it.
  16. I'd like to try before I give up. I'm sure I miss something because here, I pick numbers almost arbitrarily and get this: What is wrong with it?
  17. The OP is about creating something out of nothing, and you equate zero with nothing, so discussing zero is not off topic. Aren't you looking for an excuse?
  18. Equivalently, we know that not all humans speak Chinese and therefore speaking Chinese is an inborn ability. How are we humans imprinted at birth by neutrinos? Equivalently, I discovered the flatness of Earth before knowing anything about astronomy and therefore can't deny its accuracy. I disagree. Woo woo is not an accurate description of how this sounds.
  19. Was it? Let's see... 0oC = 32oF, right? Then, 0oC+0oC = 64oF, right?
  20. No, it was not a prediction. Homogeneity was an assumption long before the inflation idea. Inflation retrospectively explains it. It also retrospectively explains flatness, small non-uniformities, the absence of magnetic monopoles, and the power spectrum of CMB, IIRC. I am not aware of any experimentally confirmed predictions of it.
  21. This is correct AFAIK. Alternatively, one could say that we have tons of different ideas, which is also a problem.
  22. After the "singularity", a point on the time axis where the scale factor would be zero. There is only a low estimate for its duration. It could be as long as eternity as well. PS. If it was at all.
  23. Preceded. The BB starts with an almost uniform, hot, dense, expanding state. Inflation is a brief "prequel" (how Alan Guth calls it) that dynamically creates the BB's initial conditions.
  24. Not only helpful, but absolutely necessary. It is always done in science. This is impressed in scientists' mind endlessly in scientific education. It is rarely done in pop-sci media or youtube videos. E.g., I also stated here:
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.