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Sensei

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Everything posted by Sensei

  1. Beta decay- and beta decay+ of radioactive element is the most common way neutrinos are produced on Earth. http://en.wikipedia.org/wiki/Beta_decay Double decay is one of neutrino-less nuclear transmutations. http://en.wikipedia.org/wiki/Double_beta_decay
  2. Slit for us is smooth and thin, but after large zooming it's more like tunnel with mountains (this can be seen in any microscope). Photon traveling close to the edge of slit is colliding with one or more "mountains" and is reflected. Similar thing happens when you shine laser pointer on wall- regardless of angle at which you look at wall, you see laser dot. How? Photons colliding with microscopic impurities in the wall are reflected in the all directions. From one steady beam of photons, they're spread everywhere. Modern military airplanes and u-boats are using similar impurities on the body to be undetectable by radio and sound waves. They are reflecting waves in the all directions, instead of like smooth body sending them back to radar.
  3. Do you want to find out where your magnet has N and where has S? You can do it using compass. http://en.wikipedia.org/wiki/Compass If you don't have it, you can create it in a couple seconds. You will just need f.e. glass of water and needle (in minimum version). Move your magnet in straight direction on needle to magnetize it. After that other needles will start attaching to it. Then carefully place on water. If done properly it won't sink (if sink use magnet to take it from water and repeat). Some people attach something unsinkable to needle, but IMHO it's degrading speed in which needle will react. Now you can rotate your magnet in hand, and see how compass is also rotating synchronously. The stronger magnet you have, from longer distance you will be able to rotate or change direction of compass. You can make array of compasses and see magnetic field lines. Once I had 20+ such homemade compasses in whole apartment Funny thing, none pointed the right direction to Earth's N-S. Too many electronic equipment. The only unaffected place is here balcony. You can verify this at 12:00 looking at Sun, compass should be pointing one end to Sun, and 2nd end in Earth's north.
  4. Why not use laser cooling to freeze water? It can be direct, or indirect. In indirect method, use f.e. helium with well known wavelength of photons, take energy from helium, helium atoms will take energy from metal box where it's stored, and metal box will take energy from environment. In our case, water. Another idea is utilizing Mpemba effect http://en.wikipedia.org/wiki/Mpemba_effect
  5. If you will use 3rd party library, you will learn how to link against linkable (or dynamic) library, not compression/decompression algorithm. If you want to learn something useful, try making compression/decompression algorithm by yourself. If it's job ordered by somebody, and you will use 3rd party library, you might break license agreement they want to maintain. Some 3rd party library authors disallow selling software made with them (only share, or only share with open source depending on lib). That's mentioned in their license.
  6. People don't understand how Universe works because the way teachers learn it in primary and high school, going in chronological order of discoveries (at least here), which confuse a lot of people when they finish learning at this level and no go further to quantum physics. And here is example of this. What do you think is electricity? In closed system, number of electrons is CONSTANT. So the same number of atoms,protons,neutrons in conductors (in f.e. wires) and isolators. In electric generator no single new electron is created. Electrons existing in system are accelerated. Ek = e*U v=sqrt(2*e*U/me) e is 1.6*10^-19 C me is 9.11*10^-31 kg both constant so velocity of electron is pretty much v=sqrt(3.512624*10^11*U) (for no relativistic speeds) When accelerated electrons are colliding with atoms in wire, they're decelerated, and wire metal atoms are accelerated. This is what we call heat. The simplest way to see it is plugging plain not isolated wire to battery- after a second it will be so hot, you won't be able to hold wire in hand.. It happens all the time, not just after plugging plain wire making short circuit, but it's remaining unnoticed, heating of wire is not significant (it's spread across time). If you see photons emitted by Tesla coil, they escaped system entirely, and energy is lost. In free device generator (if it would exists) you should see no radiation to environment. It's direct sign of lost of energy.
  7. If you will call somebody else linkable library function, you won't learn anything, no? If it's homework, and teacher ordered you to implement compression/decompression without using 3rd party library, you should better listen him..
  8. We can see particle traces in diffusion cloud chamber. http://en.wikipedia.org/wiki/Cloud_chamber I have build couple such devices. The simplest one cost me equivalent of ~15 usd (40x25x25 cm size). In USA/EU might be more. Single running cost (price of 1 kg dry ice) is ~3 usd here. Result is like in this video: http://www.youtube.com/watch?v=Efgy1bV2aQo In the video narrator is mentioning alpha particles thick traces. They are Helium-4 nucleus. Beta radiation mentioned is electrons (beta decay-) or positrons (beta decay+). Cosmic rays can be muons, pions, kaons etc.
  9. Conquest/colonization of galaxy is not a solution? No, I don't think so there is too many people yet. Food can be easily produced by changing DNA of bacterias to generate proteins, hydrocarbons, vitamins, fat etc. So if we would like to (or have to- because of too large population) produce a lot of food, there is open door for doing so. Artificial food, instead of natural. It will be also more efficient, less energy used to create 1 kg of substance, than f.e. cattle, or chicken, that waste of lot of energy on their own life.
  10. Yes, of course. Uranium after emitting Alpha particle will become Thorium element. You can see to what element will decay and probabilities on right side of the all elements websites f.e. http://en.wikipedia.org/wiki/Uranium (scroll to ~30%)
  11. The whole thread is speculative, so any answer to this thread must be speculative.. Otherwise you can't basically write anything. That was Richard Feynman who imagined positron to be electron going back in time. http://en.wikipedia.org/wiki/Retrocausality See Antimatter paragraph.
  12. If we would travel to the past in the same Universe (in no multi Universe solution), there would be two identical copies of the all atoms. Are you aware that you are made of the same atoms as were in dinosaurs and Cesar? You don't need to meet literally your younger version. When you're young you were in part made of completely different atoms. When you're eating, drinking, breathing, living, you're absorbing/emitting H2O, O2, CO2, food, etc. from everywhere- so after time travel you can find your atoms in f.e. rain or on Sun (f.e. protons are emitted by Sun, and then joining with Oxygen in atmosphere forming water that you can drink and they are becoming part of your body in some cell). If you and your old atoms would then go again to time travel machine, and travel to past again and again, there would be 3,4,5... etc. etc. copies of all same atoms, electrons... And Energy/Mass would start to go to infinity, the more objects/persons would travel to past. Violating the all known conservations, starting from Baryon number conservation. After time travel to past, even taking breath would violate the all physics. CO2 from your future body could be in some star as Hydrogen atoms before it even fused to heavier atoms C and O in the past.. In multi Universe solution, object traveling in time would appear in completely new Universe, and this would mean that original Universe is losing energy-mass and new one is increasing energy-mass. It would look like violating Baryon number conservation in one Universe solution, matter would appear from nowhere, and in other place matter would disappear.
  13. Nothing is at rest, just appears to be. You think you're at rest sitting on chair, just because your whole environment is moving together with you. When you're driving car, you're at rest relative to car, but at move relative to Earth. For observer at Sun, you're moving ~30 km/s together with whole Earth.. For observer outside of Milky Way you're moving ~220 km/s together with Sun orbiting galaxy center. So you're giving priorities to observers.. Why do you think your observation is more important than somebody else observation?
  14. What said Enthalpy is about SSE extension: it's used when you enable it in C/C++ compiler, and get used usually when you are using vector math, f.e. adding/subtracting/multiplying vector with 4 elements by other vector with 4 elements. Basically execute instruction doing multiple maths in one. http://en.wikipedia.org/wiki/Streaming_SIMD_Extensions Visual Studio 2008 Express is supporting only no-SSE, SSE1, SSE2. I am not sure how it's with newer Express and commercial Visual Studio. But you're using Java, not C/C++. From experience with very math heavy ray-tracing engine I can say you that speed difference between no-SEE and SSE1 compiled project was 8% and between SSE1 and SSE2 there was also 8% (no-SSE -> SSE2 ~15%). It was tested by compiling project after switching compiler option and trying it to render the same 3d scene. SSE are truly useful when you have a lot of data to process, and they are in very simple form, like adding-subtracting-multiplying one image from another image (so there is continuous array of RGB/RGBA pixels), and programmer will call SSE processor functions manually.
  15. You should write programs for YOURSELF. Simply what you need, require, write instead of downloading ready from websites or warez. Answer yourself "what program I would use everyday", design it, and write. If you don't know- make calculator. I was always annoyed by the fact that built-in Windows (at least in mine OS) calculator has no history, so there is not visible what I calculated minutes ago.. When you will write really useful stuff, you can make website, promote it, and start selling through f.e. PayPal. You will be able to show programs in your portfolio to employer (if you won't get enough sales). What are the most used programs made by me that I am using everyday? 1. Software for managing mine stock market shares. (With open API from broker it's even possible to make your own bots buying and selling automatically..) 2. Calorie calculator for showing how much fat, hydrocarbons and protein has been eaten (it has history and I can see f.e. 1 year ago what I ate ). Learning language, just to learn language, without writing programs at least every week is waste of time. You will most likely forget everything waiting for job. Nobody is learning what functions have operating system and what fields have some structure or object in advance. You will most likely forget that struct WNDCLASS has member hCursor or hInstance anyway. When you will need it, you will have to check msdn anyway.
  16. Pointer on 64 bit machine is 8 bytes, while 16 bit index is 2 bytes, so it's 4x less memory.
  17. The first and the most important question you should ask yourself- do you want compression without losing data (GIF,BMP,PNG,TGA,PSD etc), or compression with lost (JPEG,MPEG). The first group, lossless compression methods, are utilizing any binary compression method you can develop or find on Internet. If it'll be working with txt, exe, or whatever other file format, it might be tried to compress raw image data, to see how good it is with such kind of data. To improve compression ratio, you can simply add some pre-procession like grouping r,g,b so they're continuous in memory (instead of r,g,b,r,g,b, etc. there is r,r,r ... g,g,g, ... b,b,b...) Or subtracting them from left pixels of image. If r[x] is same as r[x+1] then after subtraction you have 0, regardless of gb components that might vary. Compression method might be bad for rgb pixels that are in chunk format, and might be much better after rearranging. You can change RGB to HSV (or other) format. Then lost some precision of one or multiple components, and compress them using regular binary compression method. f.e. if image is gray scale, HSV will have the all HS=0, and the only component that will be varying will be V.. That's immediately 33% of original raw data even without compressing it. Subtract RGB of original image from compressed and decompressed RGB image, then calculate absolute, or power of them, add together and sqrt(). unsigned char rgb[ 3 ]; unsigned char rgb2[ 3 ]; int dr = rgb[ 0 ] - rgb2[ 0 ]; int dg = rgb[ 1 ] - rgb2[ 1 ]; int db = rgb[ 2 ] - rgb2[ 2 ]; int d = sqrt( dr*dr + dg*dg + db*db ); For lossless image compression method d will be always 0, because what is compressed and decompressed is the same at binary level. The smaller d, the less data has been lost. Instead of power ^2 you can use other more powerful values dr = abs(dr); dr*dr*dr so if r=0 and r1=10 10-0 = 10 10*10*10=1000 Pixels with larger change will have higher weight than those with smaller.
  18. The problem is that Path and therefor PathList contain copies of the all Cities. If you have ArrayList<Object> it's taking count * sizeof( Object ) memory. sizeof( City ) = 20, so count * 20 for each Path at least. You really don't want whole structure of City copied there. What you need is just 32 bit index, 4 bytes long, to City from table of cities. It will reduce immediately memory requirement to 20% what you have now. Using unsigned short, 16 bit, would reduce number of cities to 16384, and memory requirement to 10% of now.
  19. If city has location x,y then distance between two cities is sqrt((city1.x-city2.x)^2+(city1.y-city2.y)^2) sqrt() operation is slow to cpu. It might be possible to get ride of it during the main calculation because sqrt(x)>sqrt(y) is returning the same as x>y We are interested what is greater after all, not what is exact value, isn't? sqrt() use in final calculation of path length for user, where speed is not important. pow(x,y) with any y is also slow. For such simple thing as ^2 I would never thought about using pow(), simply x*x private double mathOption(City city1, City city2){ double powerX = Math.pow(city1.x - city2.x, 2); double powerY = Math.pow(city1.y - city2.y, 2); return Math.sqrt(powerX + powerY); } Change to: private double mathOption(City city1, City city2){ double dx = city1.x - city2.x; double dy = city1.y - city2.y; dx *= dx; dy *= dy; return ( dx + dy ); } And try whether it's running faster. Did you thought about precalculating data? If you have x cities, you can allocate x^2 distance table and fill it at beginning And then reuse instead of calculating over and over again distance from city to city[j]. But this would require using index to city, instead of City object. distance=distances[ i*count+j ] i = 0...count-1 j = 0...count-1 Dynamic tables are slow, they require reallocating and copying data. In the worstest implementation of dynamic table, it's extended every added element to array. Inserting element at beginning must end up with copying and pasting the all elements (the only way to get ride of it, is using double linked lists. I doubt java uses them). If we know how many elements table will have (city count), better is to allocate static table and then fill, instead of relying on dynamic table/array. (I noticed this in Path class)
  20. GR predicts existence of gravitational waves. That were never observed and detected, even though there was pumped hundred millions dollars in building devices for detecting them for 53 years since 1960.. Just a thought.
  21. Caesium was chosen in 1967, because of great precision. Before that there was used other ways to calculate 1 second f.e. 1/86400 of Earth's day. If light speed is not constant, but variable, then airplane with v=1000 km/h emitting light in direction of flight should give us v= ~300,000 km/s + 1000 km/h/3600s/h=~300,000.277(7) km/s Instead there is Relativistic Doppler Effect observed, instead of greater speed. XX century new modern physics was developed to explain this observation.
  22. Why do you want to use Basic? They're interpreted, not compiled (unless something changed the last time I used Atari Basic). Math needs efficiency. Visual Studio Express C/C++ is free, and allows making the fastest code. http://www.microsoft.com/visualstudio/plk/downloads#d-express-web or simply enter "visual studio express" in google.
  23. 13 posts with science has more value than 10,000 with trash..
  24. Trolls don't survive long on physics forums.. What a nonsense showed in your video. It's never hitting Earth.
  25. People believe that we are emptying our planet. It's incorrect thinking. Atoms that were in oil are still in our planet. They just changed from one molecule of hydrocarbon to another molecule of hydrocarbon (e.g. plastic), or to water and CO2 while burning. These atoms nowhere go outside of our planet! The less will be oil, the more technologies of reusing old materials will be in common use. In capitalism, what is cheaper wins. If flying to asteroid and bringing it here would be cheap, everybody would be doing it. It's just a matter of money.. People that build Saturn V etc. didn't lost knowledge how to build them. They stopped building them because there was no more money from government to sustain conquest of cosmic space.
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