Sensei

Senior Members
  • Content count

    3947
  • Joined

  • Last visited

  • Days Won

    3

Everything posted by Sensei

  1. Uncontrolled decompression (e.g. caused by debris from engine) can force pilots to immediately decrease altitude from ~10 km to ~3 km, which decreases possible to flight range (on one or none engine).. Inability to decrease altitude can have tragic consequences like in Helios Airways Flight 522. https://en.wikipedia.org/wiki/Helios_Airways_Flight_522 (irreversible coma, damage of brain and organs, caused by lack of Oxygen)
  2. Time to rethink the Earth's motion?

    Jump inside of train.. Are you leaving train.. ? Jump inside of airplane.. Are you leaving airplane.. ? Particles, molecules, or objects which didn't reach escape velocity will be attracted toward Earth. https://en.wikipedia.org/wiki/Escape_velocity Planets are losing their atmosphere all the time, when highly accelerated particles from cosmos, and mostly from the Sun are giving them enough kinetic energy. Earth and Venus are leaving tail behind them. When Sun will start burning Helium-4 fuel, and other heavier elements, temperature will increase and even more energy will be reaching planets, and entire inner planets will be vaporized..
  3. Parallax of the stars

    I would start from drawing two right triangles on piece of paper. In small scale e.g. a=10 cm, b= 1.5 cm (and c=sqrt(a^2+b^2) obviously). You can check angle using simple protractor. If you will understand idea behind parallax in small scale, you should be able to solve it also with millions or billions of kilometers.
  4. Higher-ordered "quarks"?

    Did you check crackpot websites? Quark-model is a method to unify previously discovered "particle zoo".. When particle accelerators were created, new and new and new particles have been discovered, one by one, introducing consternation, confusion into quantum physicists community. "Particle zoo" in quantity a couple hundred of particles, mesons and baryons. https://en.wikipedia.org/wiki/Particle_zoo List of particles: https://en.wikipedia.org/wiki/List_of_particles The first was discovery of so many different particles, later there was attempt of reunification of them to smaller quantity (and introduction of quantum numbers which are conserved during creation (or not), and conserved during creation and decay). Sometimes particles differ just by half-lives and/or decay mode (like neutral Kaon long and neutral Kaon short, while their rest-masses are the same (at least according to current methods used to measure their masses))
  5. Units (split from What is Time?)

    Imagine following experiment. We start with object at altitude/height h=20m, then we release object, and while it's flying we record position of object on timeline (easily done with modern high speed cameras). We received graph h(t). It can be put to e.g. Excel or OpenOffice Calc Spreadsheet. They have simple unit meter m. One entry of table per single exact time. Altitude measured from the ground. If you subtract entries in spreadsheet, A2-A1, fill it down, you will receive distance traveled each second, you can (in memory) divide this distance by e.g. 1s time delay between them. Put it in column B in spreadsheet. First row will be empty because of lack of data (B2=A2-A1... B3=A3-A2... B4=A4-A3... and so on..) (h(1)-h(0))/(t(1)-t(0) = dH/dt = local velocity at 1st second (h(2)-h(1))/(t(2)-t(1) = dH/dt = local velocity at 2nd second (depends on initial altitude whether there will be 2nd second of flight) (h(3)-h(2))/(t(3)-t(2) = dH/dt = local velocity at 3rd second (depends on initial altitude whether there will be 3rd second of flight) dH/dt has unit m/s. Now imagine that you're interested in how this velocity changes over time. It's acceleration. You have to take B3 and subtract from it B2 (In memory you divide by 1s). You have dV/dt. With units (m/s) / s = m/s^2 = m * s^-2 And this is how such example spreadsheet could looks like: I used 0.1 time delay between entries to show how it changes. Initial A1 = 20 - 1/2*9.81*T1^2 and then Edit > Fill > Down
  6. Units (split from What is Time?)

    There is needed context in which they are used. e.g. If you have energy E0 at the beginning of experiment at time t0=0s and after 1s delay at time t1=1s there is energy E1, you can write equation (E1-E0)/(t1-t0) = dE/dt and then you use multiplication/division of units to find out what are new units of newly created power P. Energy was in kg*m^2*s^-2, subtraction E1-E0=dE and t1-t0=dt don't change units, but division by time does.. (kg*m^2*s^-2) *s^-1 gives you kg*m^2*s^-3.. Second to third power looks weird, but you have to remember how to get to this result knowing equations P=I*U=dE/dt .. It will help. Equation where energy has been multiplied by energy (J*J).. or where volume has been multiplied by velocity (V * v)... or where area has been multiplied by other area (A*A)... etc. ?
  7. God and the Big Bang

    It often ends up this way, when there is collapse of society, education, knowledge, trade. Such times are called now "Dark Ages" (because of lack of written information about what exactly happened) Ancient knowledge has been many times lost, forgotten, and remained just shreds of knowledge unable to be read, interpreted, understood by many generations of people living after collapse. Some day, somebody, priest of new religion, can repeat E=mc2 without even having any idea what each of these letters mean, in some temple (like this happened with YHWH).. I don't share your optimistic opinion. It can be very easy. At the moment, you can't even read data from tapes which were created 30 years ago. Knowledge gathered on CD/DVD/Blu-ray, won't be available when the last CD/DVD/Blu-ray reader/writer will stop working, and new one won't replace them. There is just a few people (perhaps less than per mille of per mille of population) knowing how to make these devices, how to fix them, and how to recreate them, if the all devices would be gone.. Couple thousands years ago knowledge gathered on stones was less vulnerable for loss.
  8. 1 000 000 Posts

    There is such a tool: webarchive... You can try going "back in time" to older version of website (as long as it was backed up by them.. this requires that site must be publicly available, so web crawlers added URL to their databases). e.g. https://web.archive.org/web/*/scienceforums.net
  9. God and the Big Bang

    I could dismiss iNow from his new, unexpected, god position, within seconds, asking some "wonky" questions about quantum physics.. (but putting into consternation Nobel prize winners in physics is even more amusing..)
  10. God and the Big Bang

    It used to be science forum... I miss that...
  11. incomprehensible

    Study quantum physics and science.. it will take you closer to the truth for sure.
  12. time?

    I know such smart sentence: "spend your time wisely".. Majority of people are wasting their time IMHO.
  13. time?

    In classic physics time is 4th dimension (with three spatial dimensions *) ). It allows positioning events or objects on timeline. e.g. position of object e.g. car A and car B is in 3D (xyz) 0,0,0 on parking.. So they would have to overlap without yet another parameter. Add time, and you will have: 0,0,0, today 17:00 and 0,0,0, today 18:00 (one hour difference between them), and objects A & B won't overlap anymore.. *) in some non-classical extensions it might be different number of dimensions than three. Thee dimensional space article: https://en.wikipedia.org/wiki/Three-dimensional_space Four dimensional space article: https://en.wikipedia.org/wiki/Four-dimensional_space
  14. problem about processing

    You declared fire parameters at the beginning as arrays: float[] fireX= new float[totalFireNum]; float[] fireY = new float[totalFireNum]; int fireSpeed = 15; float[]fireLeft = new float[ totalFireNum]; float[]fireRight = new float[ totalFireNum]; float[]fireTop = new float[ totalFireNum]; float[]fireBottom = new float[ totalFireNum]; ("fire" is inappropriate name. You rather meant "missile".. ?) but later you're treating them as regular scalar variables... e.g. image(fireShape, fireX, fireY, fireW, fireH); fireX = fireX+fireSpeed; fireRight = fireX + fireW; fireLeft = fireX; fireTop = fireY; fireBottom = fireY+fireH; (addition of float/integer to array pointer (address) ?!) You should make loop going through entire list of missiles, display them one by one, and change their positions independently, incrementing/changing array fields..
  15. A question about American politics

    Involvement of NATO (not just USA) was direct result of massacres and mass murders.. https://en.wikipedia.org/wiki/List_of_massacres_in_Yugoslavia https://en.wikipedia.org/wiki/NATO_bombing_of_Yugoslavia It was completely unacceptable for world community.
  16. Reason of somebody existence can be told after many years (usually hundreds, thousands etc. from eternal perspective) e.g. without father and mother of Einstein (go deeper and deeper in family tree, searching for older predecessors), he would not be born, and would not be able to influence science.. (and somebody else would have to take his role in other version of the Universe)
  17. In computers there are needed just 0 and 1, bit, to make the all other possible combinations, after using enough of bits together. But it's wise to have checksum, to be able detect damage in code. Damage in DNA is inevitable, simply because of some of radioactive Carbon C-14 will decay to Nitrogen-14, sooner or later: [math]_6^{14}C \rightarrow _7^{14}N + e^- + \bar{v}_e + 156 keV[/math] And such data is destroyed in unpredictable way.
  18. simple smoke bombs

    As always, John, you draw conclusions from words that have never been said.. "or other cooled solid substance which is sublimating at room temperature" means it's certainly not liquid Nitrogen.. (liquid Nitrogen is... hmm.. liquid, not solid substance....)
  19. simple smoke bombs

    Burning fuel creates various intermediate toxic compounds. But if you would use e.g. dry ice, liquid Nitrogen etc. etc. or other cooled solid substance which is sublimating at room temperature, it could pretend "smoke".. Search Google for "dry ice+water" e.g.
  20. Elementary electric charge e=1.6021766*10^-19 C is measured in oil drop experiment. Electric field created on metal electrodes keeps oil drop levitating (or even moving backward) against gravitation which tries to accelerate oil drop toward Earth. https://en.wikipedia.org/wiki/Oil_drop_experiment
  21. (let's assume that answer for premise "Every particle is an excitation of it's own field?" is yes).. Who said so that they're stable? e.g. Muon- decays to electron (and electron anti-neutrino, and muon-neutrino) e.g. Muon+ decays to positron (and electron neutrino, and muon-anti-neutrino) And this happens extremely fast.. Electron/positron can't decay anymore (at least according to current Standard Model knowledge..), but can e.g. annihilate with its anti-particle. And as a result, different set of particles (and eventually anti-particles) will appear instead. IMHO fields are mathematic models currently used to describe what particles and anti-particles are doing..
  22. More than half your body is not human

    That reminds me "zombie-ant fungus" ("Ophiocordyceps unilateralis") https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis (read Life Cycle at least)
  23. Stuff in Space

    Geostationary orbit.. https://en.wikipedia.org/wiki/Geostationary_orbit
  24. Pigmentation on one half of my stomach

    If it just appeared, it could be sign of internal bleeding. e.g. ps. Make photo and attach in reply. It'll be easier to analyze..
  25. E=h*f ?

    Because his understanding of physics is so weak.. ?