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Showing content with the highest reputation on 07/14/23 in all areas

  1. OK so we are going to work from general experience What holds up bouncy castles, lilos, air beds, bicycle tyres and the like ? I am going to answer this in a spoiler considering the circumstances and it is general science you will need to know something about. Now associated with the process we call osmosis, there is an increase in pressure of a fluid, which is not air. What do you think this fluid is ? You have obviously found your way round this site very well. Did you read any of the rules ? Two things. Firstly new members are allowed 5 posts in their first 24 hours. This is an effective impediment to the bad guys. Since you have one left, think very carefully before you reply. After one day you can have as many posts as you like and conversation can continue normally. Secondly, the homework section has some special rules. We are not allowed to just tell you the answer, as we could in the biology section. So is this actual homework or just part of your catching up. There are good folks here who would encourage that.
    2 points
  2. But you devise experiments based on what you expect from theory. You might see an unexpected signal, but if the mechanism isn’t right you just see nothing. How many there are correlates to the chance you will detect one. If you detect one in a billion and your flux is one per second, it could be years before you detect it. And you need to detect more than one, because you need statistics. Detecting one won’t be distinguishable from the noise. That’s not how you framed the thread
    1 point
  3. It is not. Quantum mechanics prohibits this. No technology overcomes laws of nature.
    1 point
  4. There was a time when desperate doctors would deliberately give patients a dose of Malaria, to try to kill the infectious agent of syphilis with the resulting high temperature. It might sound a bit drastic, but having syphilis in those days, with no other cure available, was pretty drastic itself. Maybe in the future, if syphilis evolves to be antibiotic resistant, they might need to try it again. Maybe somebody should be researching how to maintain a high temperature in humans, without damge or risk to the patients. Athough that might not turn out to be possible.
    1 point
  5. I'm not surprised. It is a very poorly structured question and the above post by @TheVat shows that much of it's premise seems to be factually inaccurate. So how do you tackle a question like this? The best results should be gained by reproducing verbatim the texts provided on the topic during your coursework. This is what the examiners will be expecting. However, if you have missed many of your classes, and have been unable to catch up for one reason or another, that option is unavailable to you. If you decide to attempt the question (a case could be made for skipping it), your first challenge is to decide whether the 'this' in the last sentence applies to only the preceding sentence, or the two introductory sentences as well. It isn't at all clear. The second sentence is a partial answer to the opening statement. But we can add a little to that and maybe gain an extra mark. Mainly we should focus on expaining the third sentence. I would present something like this: Probably, not exactly what the examiners were looking for but I'd be reasonably confident of getting a couple of marks for that.
    1 point
  6. Raised body temperature activates the immune system and helps it work more efficiently. It also creates a less receptive environment for bacteria and viruses that are very acclimated to a specific narrow temperature range and will replicate more slowly if it gets too warm. The trick is to get these good effects without driving the temperature so high that it harms or kills you. Which is why fever management, figuring out when to hold off on fever suppressing drugs and when not to, is an important part of modern medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7195085/ The Fever Paradox.
    1 point
  7. We still do sometimes; it's very effective.
    1 point
  8. You see, I read each as: u r joking - you are joking ur joking - you're joking
    1 point
  9. Here is why the total spin J for the sss baryon cannot be 1/2, AFAIU: The wavefunction for a baryon (a fermion) has to be anti-symmetric. In the ground state, this wavefunction is a product of the wavefunctions for spin * flavor * color. This product has to be anti-symmetric. Since all three quarks are of the same flavor, the flavor wavefunction is symmetric. Thus, the product of the wavefunctions for spin * color has to be anti-symmetric. Next, (Phy489_Lecture9a_2013.ppt (utoronto.ca)) Since the color wavefunction is anti-symmetric, for the product of wavefunctions for spin * color to be anti-symmetric, the wavefunction for spin has to be symmetric. The three 1/2-spin wavefunction is fully symmetric only in the case of all three spins being the same, i.e., J=3/2. It is not fully symmetric if one spin is different from the other two, i.e., if J=1/2. QED
    1 point
  10. Lol I get the offer to be a co author quite often. My reply is always the same. In that I have no issue with assisting someone with their models by pointing out better methods, supplying corrections etc I have no interest in receiving credits for doing so. The real reward is helping someone improve in their understanding. However thanks for the offer. You and I look at physics as a hobby a bit differently each week I try to find a new challenge or model to study as a good hobby to my way of thinking is something that has the goal of continual improvement. Yes I recognize that in regards to physics its not an easy task. Anyways I look forward to see how you handle the vacuum catastrophe.
    1 point
  11. "Simply a can of hydrogen", eh? To get 18g of water would require 45l of hydrogen at atmospheric pressure and room temperature. So for a litre of drinking water you would need 2.4 m³ hydrogen at STP. You would compress it, of course, perhaps to 200bar, in which case the volume per litre of water would be 12l. But you would then have the weight of the pressure tank and the conversion catalyst, or burner + condenser, to react the hydrogen with atmospheric oxygen. I find it hard to imagine the weight of all this kit would be less than 1kg, which would be the weight of a litre of water. So I don't see this working out in practice.
    1 point
  12. I found this: https://www.physicsforums.com/insights/a-beginners-guide-to-baryons/ “For all baryons, nature demands that the combination of flavor and spin must be completely symmetric” Spin 3/2 is completely symmetric, and spin 1/2 is antisymmetric. Three identical quarks is symmetric. I notice that the uuu and ddd particles are also spin 3/2, for the same reason. I don’t have a clear recollection, since I didn’t dive into such discussions.
    1 point
  13. You have to distinguish total spin J=3/2 from spin projection. A particle of total spin J has 2J+1 possible spin projections. Eg, a particle of spin 1/2 has 2*(1/2)+1=2 spin projections, which are -1/2, +1/2. In the case of omegas, we have 2*3/2+1=4 possible spin projections, which are -3/2, -1/2, +1/2, and +3/2. If omegas lasted long enough, we would be able to perfom a Stern-Gerlach experiment and separate them into 4 distinct beams, I'm sure. Omega- has spin 3/2 for the reason that these are isospin multiplets, so all the particles in the n-plet have the same spin. The ultimate reason for that is the concept of approximate symmetry iso-spin='same spin'. IOW, baryons with the same spin have approximately the same mass. Exactly. I wouldn't call it S, as that's reserved for strangeness. I particle physics it's traditionally called J.
    1 point
  14. That's absolute laughable rubbish. They are both clearly expressing my opinion. You would have to be a bit backward, to understand it any other way because it's clearly stated that way. Backward, or deliberately nit picking for it's own sake. Of course, I'm saying it's the second. If I say, "nobody's going to want to watch blah blah blah" this is how english speaking people give an opinion in english. Of course you can come along and nit-pick on the wording and say "how do you know NOBODY will want to watch it? " . At my school, we did that for laughs until we reached our teens. I did expect more adult posting on here.
    1 point
  15. That's it, it is escalator! Been a while since I've been on one. Mixing with Americans is messing with my language.
    1 point
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