Jump to content

John Salerno

Senior Members
  • Posts

    94
  • Joined

  • Last visited

Everything posted by John Salerno

  1. Wow, the problem wasn't the password, it was the user name! For some reason a different user name (albeit one I use on pretty much every other forum) was pre-entered into the sign in page, and I needed to change it to my full name. So yeah, feeling a little foolish, but I appreciate the help!
  2. I don't understand what you mean. I am using a US keyboard, but why does that matter? I am typing in the proper letters one at a time. Not sure what else I need to check. I'm only able to respond to your post because once again I had to reset my password and re-login that way. I've also noticed that the sign in page is not a secure site, which doesn't seem especially safe to me.
  3. Hi everyone. I'm having some trouble logging into the forums. Every time I try, it says my password is incorrect. I've used Chrome to remember the password, and I've also typed it in myself to be sure it's right, but it never works. I have reset the password twice already and that usually automatically logs me in, but when I return later I'm logged out again, and logging back in results in the same problem, even though I know for sure that I am putting in the right password. I've now reset the password for a third time and am back in, but I know when I return later tonight, I'll be logged out and won't be able to log back in until I reset it again. Any ideas on how to fix this? Thanks! John
  4. Thanks! Just wanted to make sure I was learning how to do it the proper way, and not taking detours like you mentioned in the other thread!
  5. Hello everyone. I've got another probability puzzle that I actually did solve, but I feel like I may have taken a longer route than necessary to arrive at the solution. I'm wondering if there is a simpler, more elegant way to solve it than the "backwards" approach I took. Basically, the problem is that you have 40 cards remaining in a deck, with all four aces still in the deck. If you draw two cards, what is the probability that exactly one card will be an ace? I didn't know how to solve it directly, so I thought it would be easier to find the probability of *both* cards being an ace and the probability of *neither* card being an ace, and subtract those amounts from 1: 1 - ( (4/40) * (3/39) ) - ( (36/40) * (35/39) ) This works, and I understand why it does, but it feels like more of a brute force method. Is there a way to directly solve for the probability of only one card being an ace? Thanks!
  6. Thank you! After thinking about your comments for a few minutes, I finally figured it out! It was mainly your first sentence that led me to the answer! But I'm still a little confused about why it says to assume both events are independent. Isn't the second choice necessarily dependent on the first event?
  7. Hello everyone. I downloaded a puzzle app from the Play Store that has probability puzzles, and I hate to admit I'm already stuck on the second puzzle! But I feel like I'm doing it correctly, though it says my answer is incorrect. I'm just looking for some general guidance for if I'm on the right track. I don't want the answer or a direct solution. If I'm wrong, a suggestion for certain keywords I could search for and read up on would be helpful too. Here is the puzzle: First off, I'm wondering if the word "uniformly" means something that I'm not aware of. I've never studied probability, so perhaps that's one aspect I'm missing. Second, even though it seems like drawing the second sock would be a dependent event, I don't understand why it says "Assume the two choices are independent." Maybe this is another thing I'm getting wrong. At any rate, I figure the answer is: probability of drawing a sock of one color the first time * probability of drawing a sock of the same color the second time = 1/3 * 1/5 = 1/15 But that doesn't seem to be correct. Any advice or subtle hints? Thanks!
  8. Thanks. I've actually been searching for a good intro book to the subject of light, and so far I found this one: http://www.amazon.com/Introduction-Light-Physics-Vision-Color/dp/048642118X/ref=wl_it_dp_o_pC_S_nC?ie=UTF8&colid=2SSP0D0OTC6WF&coliid=I2KL719QS7RFGJ Feynman's book was an option, but I felt it might be a little too heavy for a basic introduction, although I do plan to read it eventually as well. I'll at least check out the videos for now, but I have to admit, as much as I've read about quantum mechanics, I still have a little "huh?" question mark over my head every time.
  9. I was reading about how rainbows are formed in Richard Dawkins' book "The Magic of Reality," and basically it was described as such: light passes through the upper part of the outside of the drop of water (that is in the air) and then reflects off the interior of the back of the drop and then exits the lower part of the drop. My question is, why does the light seem to react differently to different parts of the water drop? In other words, why does the light pass through (rather than reflect off of) the upper part of the outside of the drop? Why does the light reflect off the inside of the back of the drop (rather than pass through the drop, in the same way that it entered it)? Finally, why does the light then pass through the lower part of the drop (rather than reflect off of it, as it did off the back of the drop)? To put it one more way, why doesn't the light either always pass through the water drop, or always reflect off of it, rather than do both at different parts of the drop? Hope that makes sense! Thanks, John
  10. Well, I already said I saw an eye doctor. I'm going again Friday for a follow-up.
  11. Is that what it means when it says "Zincum Gluconicum 2X"? That it was prepared that way?
  12. That's why I asked my question. I don't understand why the word would be used on a box of throat lozenges that don't seem to be actual homeopathic medicine as I understand it in the technical sense.
  13. This was it: http://www.walgreens.com/store/c/walgreens-zinc-cold-remedy-lozenges/ID=prod6091086-product
  14. Yes, when I asked the pharmacist about the lozenges and mentioned that it said "homeopathic" on it, she said "That just means it's used to help prevent an illness." Clearly not the technical definition of the word. So I began to wonder if this is a secondary definition, or if perhaps it's a more palatable definition being used to "hide" the true meaning.
  15. I'm aware of the main usage of the word, i.e. alternative medicine based on the principle that a severely diluted substance which causes the symptoms of the disease to be cured will cure that particular disease. However, my eye doctor suggested I take some vitamins (A, C, and E) and some zinc lozenges to help with my current eye infection. The point was that the vitamins might help shorten the duration. But when I found the lozenges in the store, I noticed that the box said "homeopathic" on it, but it didn't seem like a regular homeopathic treatment like you typically see in those little bottles that contain pills. These were supposedly real throat lozenges that claimed to help prevent or cure the common cold. I was skeptical at this point so I decided to skip them, but I'm curious about the use of "homeopathic" in this case. Does it mean something different in certain contexts? It didn't seem to mean the same thing as the above definition about diluted substances. Thanks.
  16. According to the information I've read, it can even last longer than two weeks. But it's obvious that most of my symptoms are going away, like redness and irritation. I'm basically left with the swollen eyelids and discharge now, which my eye doctor said is normal at this point. It definitely took a while to START getting better at all, though.
  17. No, I didn't have any tests done to confirm it. I doubt most doctors think it's worth the effort. My sister and brother-in-law both seemed to recover within days of starting their antibiotics. The same with my nephew, so perhaps his was bacterial as well. I hope so since the doctor gave him antibiotics. I think my niece's condition lasted longer, about a week or so, so it's possible hers was viral. It's entirely possible that all cases in the family are bacterial and I was just misdiagnosed as viral (by one doctor, since their opinions were the opposite of one another), but all my symptoms seem to indicate viral (to my layman understanding, at least). So that's why I asked my question. I was wondering if the viral and bacterial versions are two completely separate conditions (which I would think they are) or if exposure to one can lead to the other. Because it confuses me why we would all have different types...
  18. I'm currently in week two of conjunctivitis, originally diagnosed as bacterial by my general doctor and then later diagnosed as viral by my ophthalmologist. Based on my symptoms and what I've read on WebMD, etc. I'm inclined to think it's viral. I took antibiotic eye drops (prescribed by my doctor) for about 3 days before seeing my ophthalmologist, who advised me to stop using them and instead prescribed corticosteroid eye drops meant to help with the inflammation and irritation. (Those don't seem to be doing much good either.) Anyway, all of that is just to ask my question. My niece had pink eye a week before I got it, so I assume I caught it from her. Shortly after I got it, it showed up in my nephew, and then both of their parents as well. As far as my sister and brother-in-law, they actually had tests done that determined their version to be bacterial. We don't know for sure which version my niece had. I assume she's the one who spread it to all of us. So I'm wondering, is it possible for the bacterial version to be caught from exposure to the viral version, and vice versa? If my ophthalmologist is right and I do have the viral version, then how could I have gotten that if my niece had bacterial? Or if my niece also had viral, how did my sister and brother-in-law get the bacterial version? I suppose we could have gotten it from two separate sources, but it seems likely that it was from my niece. Thanks.
  19. I'm reading this book right now. Just want to note the author is not Dan Barker.
  20. I don't know who that "authority" is, but thus far I'm finding the book to be very similar to A Briefer History of Time. It covers a lot of the same material, but it also discusses M-theory in more depth (which I think is the topic of the next chapter I have to read). I guess it depends on what is meant by "sell-out."
  21. Gah, I really want to wrap my head around this but it just doesn't make sense! I've read these replies, I've read Wikipedia, I'm currently reading "The Grand Design," but I still don't understand this concept (from Wikipedia): I just don't see how the uncertainty principle is anything other than a description of the problems with measuring techniques, rather than an inherent property of the system being measured. I fully understand how measuring a particle's position, for example, will affect it's momentum, but that still seems like a problem with current measurement technology rather than with the properties of the particle itself. Why isn't it the case the particle still really does have a specific position and momentum, and the problem is simply that we cannot measure them both simultaneously? I don't understand why the uncertainty principle HAS to mean that a particle never has a specific position and momentum at any given time. Finally, in reading "The Grand Design," a distinction seems to be made between the uncertainty principle and the idea that measuring something will necessarily change it. Are these two different ideas, or are they the same thing? I thought that the uncertainty principle was basically saying if you measure one thing, it changes something else. But the book seems to be suggesting these are two distinct ideas in quantum physics. Thanks.
  22. Hmm, but you seem to be framing the discussion of determinism (or lack thereof) within general relativity, which preceded the uncertainty principle. Are you suggesting that GR and the UP are saying the same thing about determinism? It seems to me that the UP is making a much stronger claim about uncertainty and non-determinism than the consequences of GR suggest.
  23. Hmm, very interesting. I know I need to read much more about QM than Hawking's brief summary, so that's a good start to get a sense of what it's saying. I need to find some other books for the general reader.
×
×
  • 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.