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Sensei

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Everything posted by Sensei

  1. I have deja vu.. Many years ago there was a thread about it..
  2. ...I thought it is called "fruit"... Some plants require/prefer to pass through animal stomach and gastrointestinal tract, and grow up with excrement (fertilizer), a few kilometers away from mother plant.. One could utilize reptile ability to regrow tail, to repeatedly eat part of animal every couple months, without having to kill it.
  3. Yes.. when you have to horizontally scroll text to be able to read them all.. Some prefer "reverse notation".. e.g. main_error_insufficient_permissions so other "main_" strings/variables/classes etc. are listed in alphabetically sorted order together in IDE, and other "main_error_" are listed in sorted order together in IDE, etc.etc. If you have human natural language order, they would be all mixed together. "main" is place where is used specified string (in Android app), "error" is what is subject of specified string. e.g. you have class which has name PasswordEditText, so prefix will be "passwordedittext_" and the all its strings grouped together in strings.xml This has to help them listed together due to sorting algorithm in IDE (auto-fill/auto-completion feature of IDE).
  4. Unless there are some interesting ores on them..
  5. Did you check how small they are? ~ 150 and 280 times smaller than the Earth's Moon..
  6. You can avoid most lung cancers by quitting smoking and giving up burning fossil fuels..
  7. W3Schools has Python tutorial https://www.w3schools.com/python/
  8. I think so, in our deliberations, we can safely exclude outermost layers of the Sun (where the density is less than water on Earth), and concentrate just on the solar core. Mass of the core is 34% of Msun = 0.34 * 1.9885×1030 kg = 6.761*10^29 kg Radius of the core is ~20% of Rsun = 0.2 * 696,342,000 m = 139,268,400 m So, using your above escape velocity from the center of object, we are getting: v2 = 3 * 6.67*10^-11 * 6.761*10^29 / 139,268,400 = ~9.714*10^11 v=sqrt( 9.714*10^11 ) = ~ 985,600 m/s = ~1 million m/s = ~1000 km/s
  9. Escape velocity equation (from surface and further) is: [math]v=\sqrt{\frac{2 G M}{r}}[/math] for any M, we can find any such so small r, after reaching it, escape velocity is equal or exceeding c. So, for the Sun, it'll be: [math]r=\frac{2 * 6.67*10^{-11} * 2*10^{30}}{299792458^2}[/math] approximately 2968 meters. Multiply by millions and billions of years sucking in any (hypothetical) DM, and these Msun and Mearth must already have it included.. I think so escape velocity equation has sense only from object's surface and further. If (electric neutral) particle is inside (passing through) of e.g. star or planet or other object, it's attracted from the all directions, and calculation which is just toward center of it, is at least "imprecise".. I said concentration, not quantity. Concentration requires both quantity and volume.
  10. Maybe you should make article and make it sticky what dimension means in physics.. so they won't confuse it with sci-fi vision of other dimensions..
  11. @John Cuthber Nope. In previous post, you mixed up Theresa May with Thatcher and now just pretending that during writing words ("It's not so long since we had a prime minister who studied quantum mechanics. (...)") you meant Thatcher, when you realized your mistake after I pointed out that education of May is geography.. Nobody would use "not so long" for something that happened over thirty years ago. https://www.merriam-webster.com/dictionary/not long ago
  12. 1) take checkered paper 2) pick up some random points x1,y1 and x2,y2 (integers to have easier the next step) 3) draw line passing through these points (single cell of checkered paper is 1x1 in x and y units) 4) think I think that visualization of this is essential to understanding what equation should be made..
  13. Who are you talking about? On neither Theresa May nor Margaret Thatcher Wikipedia profiles there is not a single word about "quantum", "physics" nor "mechanics".. On May's private website there is not a single word about it either.. Weird. https://www.tmay.co.uk/about Just Geography at Oxford. Physics is not mentioned any single time on the list of finished education of UK prime ministers either. Weird. https://en.wikipedia.org/wiki/List_of_Prime_Ministers_of_the_United_Kingdom_by_education Margaret Thatcher wiki "She studied chemistry at Somerville College, Oxford, and worked briefly as a research chemist, " ("not so long ago" for "30 years ago" is weird statement in the mouth of human being like you, even if you conflated (mixed up?) "quantum mechanics" with "chemistry") ..but that position is already taken by you..
  14. You can attach image in reply on this forum, if it is absolutely required. Below editor you have field with "Drag files here to attach, or choose files..."
  15. Decreased amount of matter (on the right side of equation) is accompanied by decrease of volume (on the left side of equation). Radius of sphere you know from mathematics.
  16. Any object with temperature T is emitting photons. How much energy have these photons depend on temperature of the body. Your biological body is also emitting infra-red photons (therefor one can use IR thermometer to remotely check temperature, or IR camera to detect people or animals from longer distance). If body is enough hot, there are emitted visible photons (and your eyes are able to detect them as light). Please read black-body radiation article on Wikipedia for more details about this subject: https://en.wikipedia.org/wiki/Black-body_radiation
  17. In the worst case scenario (opposite side of the Earth) it is 2 * 20,000 km / 300,000 km/s = 0.133 s... plus delays caused by hardware.. With satellite transmission (instead of underwater oceanic fiber wire) it would be even worse.
  18. That requires extremely well educated population, extremely well informed, extremely well understanding everything.. ..if population is intelligence, quantum physicists, you cannot lie to us... (one can try, but the only thing you will get is smile, which can be interpreted "I know you are telling BS") Merkel graduated quantum chemistry, her husband too... what UK have.. ? I said to somebody here, Merkel is the only politician who could speak with me... (the rest would not have idea what I am talking about anyway so waste of my time)
  19. @Raider5678 Absolutely. Descriptive variable names, descriptive class names, descriptive structure names, descriptive constants etc. etc. are essential for readable and maintainable in the future source code.. ps. Example from my yesterday project: context.getString( R.string.voiceedittext_speech_error_insufficient_permissions ); .... I don't need to comment, I hope so..
  20. I think, you are not entirely fair with them. Any (at high enough position) politician is liar.. Without lying to people, they would not get votes and sustain position.. Promising something which they cannot do, or don't want to do, or doing it would be plain stupid, I also consider as "lying to people".
  21. Charged fermions react to external electric and/or magnetic fields. Uncharged fermions i.e. neutrinos interact via weak-force (and gravity)..
  22. ...that is why in my previous response, not with a reason, I imagined black hole... i.e. escape velocity from black hole is >= speed of light..
  23. These "clumps of matter" are made of ordinary matter i.e. black holes, stars and planets.. Already.. i.e. they are source of gravity which should attract whatever else what reacts only to gravity.. You described situation in which DM is alone (and does not interact even with itself), without any ordinary matter around.
  24. If dark matter reacts only to gravity, the largest concentration of it should be inside of black holes, stars, and planets. In the core center...
  25. Thick atmosphere = large pressure of atmosphere at the surface.. Habitable for human being is the not same as habitable to any organic life form and even less for inorganic forms.. Supply of energy might be due to planet's internal activity e.g. volcanoes, tidal forces etc.
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