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Everything posted by Kedas

  1. Kedas

    How do we think?

    Try to be smarter than this neural net that has been learning for some time. http://www.boingboing.net/2005/05/10/cool_tools_on_20q_a_.html You can try it here http://20q.net/
  2. A general rule I know: longer than 5min. without oxygen is trouble. But I'm sure there are many parameters changing that. One that I know is the temperature of the body/brain, cold is better. One more thing, I don't think you can talk of an intact brain since it's changing all the time. or you will have to define that better. But some medical people will probably have a more correct answer.
  3. To give you a practical example: http://www.pewclimate.org/global-warming-basics/facts_and_figures/greenhouse.cfm
  4. I just want to add something to this discussion about what is assumed easy by most people but hard for everyone. some consider it an art http://www.amazon.com/gp/product/0721670113/102-5350392-8443362?v=glance&n=283155 I didn't saw it mentioned here but cultural differences are also a big factor in understanding and that is even assuming that there is only one truth. some experience We have a programmer in China that works for us. Communicating with him about problems that need solving is a lot harder than you would think. Here a recent article that is related to this http://www.sciam.com/article.cfm?chanID=sa003&articleID=00087E7F-7EC8-130A-8AB283414B7F4945
  5. I know permeability and permittivity don't change based on field strength etc. but they do change based on the material the field is in. Let me give you an simple example about what I mean: If you throw a ball in empty space it will have certain behavior properties. Now when you do the same in air it will be different. Instead of saying these are properties of air I say it are the properties of the ball when it's influented by the air. (the ball is the field) Why the little 'twist', because then you don't give 'nothing alias empty space' a property, because then you say a field property when it's not influented.
  6. Well if space isn't curved then the same effect can be reached if you curve the object in it instead of the space. an object is somethng so it can be curved. electric and magnetic field
  7. Is it then not more 'correct' to talk about 'curved objects' in a gravity field. I don't see this as a property of space but the property of a field when it isn't changed with matter.
  8. If we assume that gravity curves spacetime doesn't that mean that we accept there is an ether otherwise there is nothing to curve.
  9. Sorry for changing the subject a little but I was just thinking: is the force of gravity totally immune to time? With other words if an object moved at almost c to or away from a gravity field (other object). Wouldn't any partical/information exchange be slowed down and therefore decrease the effect(gravity) of the partical/information exchange. Has this been measured/tested in some experiment ? This would cancel out any gravity effect of an object if it reaches the speed of c. So a photon could have a mass but for al observers no mass can be detected due to it's speed. I'm sure I made a mistake somewhere
  10. Does someone know if a GPS system also include an electronic compas or is the compas software based (2 know positions in a street one after the other) Simple test: If you are standing somewhere with your GPS system and you turn around (on the same position) does your system notice it?
  11. The first thing they do is split the white light in to 3 colours, that isn't needed with led since they start with the three colours. hence they can be located at a different position so you already have a factor 3 of lm/mm² less to get the same effect. Secondly I don't think that having a bigger surface that generates the needed light is a disadvantage, maybe it's an advantage since they can modify the shape of that surface. In worste case they need an extra lens. A surface of 3cm*3cm (or 16/9 ratio) per colour should be more than enough to have enough lumen for your projector. Generating the natural colours is probably not a problem since they said this about those mini projectors: edit: some simplified math (http://www.luxeon.com/products/family.cfm?familyId=7) 2000lumen/3colours = 667lumen/colour red 667lm/140lm/led=5Leds price: 5*6.5dollar=32.5 blue 667lm/30lm/led=22Leds price 22*8.5dollar=187 green 667lm/80lm/red=8leds Price: 8*8.5dollar=68 Led price for about 2000lumen=287.5dollar so not more expensive than a lamp
  12. Give me numbers.... look at this:http://www.luxeon.com/pdfs/DS45.PDF Keep in mind that no one says that you only can use ONE LED like it is with lamps
  13. I don't think that's the case because there is no monopoly. The only reason I think is that they just need time to develope the new technology it's not like they just have to replace the lamp with the leds and done. They will probably use three different colour led's this way skipping the filtering of white light in to colours. The mini version are just there to show that it can be done they 'just' need to put more leds in it to have a more mature led based projector I would be surprised if there is no 2000lumen or more LED based projector on the market nex year. And I'm going to buy one
  14. You mean using leds would mean they wouldn't have a 'point' light source. I don't think that's a problem. I just found these mini versions. (not much data though) http://www.techtree.com/techtree/jsp/article.jsp?article_id=67373&cat_id=581 and http://www.akihabaranews.com/en/news_9790.html Some power LED info: http://www.theledlight.com/LuxeonLEDs.html price 16dollar/3W LED or 25*16=400dollar that is also the price of current lamps. 25LEDs*45lm/W*3W=3375lm
  15. Hi, Does someone know why they don't start using white leds in those projectors? You need only about half the energy and what is much more important the lifespan is about 50000 hours. For most projector lamps that is more than a factor 10 longer. So what is stopping them to use LEDs? some info Lamps: Current home theater projectors are all working with a lamp example of a projector: http://www.projectorcentral.com/projectiondesign-F3_SXGA+.htm Here you get 4000Lumen for an 250W lamp (16 lm/watt), lifespan 8000hours LEDs: White LEDs have in best case 80lm/watt http://www.lrc.rpi.edu/resources/news/enews/Apr05/general251.html (available now between 25 and 35lm/watt)
  16. A plant doesn't have a brain so it can't die because the brain doesn't get enough oxygen....
  17. velocity is a vector, speed isn't The scalar product velocity.velocity = speed² because Cos(0)=1 making KE not a vector.
  18. Earth is also a 'spaceship' you know (although without engine) It's just an alien race that figured out how to travel by moving their entire solar system. (this way they never have to worry about going back or getting lost) Well, for now it will just have to stay under pneudoscience LOL
  19. http://www.space.com/imageoftheday/image_of_day_051110.html It could be a spaceship with an engine failure.... Well, it can also just be a star that is traveling fast due to some unknown reason. What brought this star up to speed? A black hole seems to be the only explanation.
  20. Sorry I'm wrong forget that about the minus.
  21. It's c² = a² + b² - 2ab cosC (notice the minus) if C is increasing (0to90), cosC decreases, c is increasing.
  22. http://campus.northpark.edu/math/PreCalculus/Transcendental/Trigonometric/Geometry/ You will have to take the first derivative to 'the angle between them' of your solution. This will give you the ratio between the angle change and the lenght change.
  23. You can put a cylinder around the stream' date=' all the water that goes in the cylinder is also coming out of the cylinder and since the cylinder isn't collecting or creating water in any way the flow rate must be the same at the beginning and the end of the cylinder. Assuming that it would remain its column shape despite the collision with air molecules: The speed will increase and so also the 'flowrate', although we can't talk about a flowrate since we only have one object with certain dimensions. If you would have a lot of those 'columns' fallen after each other then the distance between them would increase together with an increasing speed making the amount of 'columns' passing per min. (flowrate) at any height constant.
  24. The constant collision with air made the water break up.
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