How EM radiations propagate through the air and what is an EM field.
Ask HN: What scientific phenomenon do you wish someone would explain better?
521–530 of 839 posts
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#522The unification of electo-magnetism. I know the classical equation well, but never formally studied physics and have never been able to get my head around Maxwell's equations.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#523I would like to understand how cellular biology processes actually work. Like, how do all the right modules and proteins line up in the right orientation every time? Every time I watch animations, it seems like the proteins and such just magically appear when needed and disappear when not needed [0]. Sometimes it's an ultra-complex looking protein and it just magically flys over to the DNA, attaches to the correct sp…
They don't. This is a pet-peeve of mine, and it's reinforced by animation after animation. Everything is being jostled around randomly. The molecules don't have brains or seeker warheads. They can't "decide" to home in on a target. The only mechanisms for guidance are: diffusion due to concentration gradients, movement of charged molecules due to electric fields, and molecules actually grabbing other molecules. It's…
It would be great if they showed just one animation up front of the chaotic mess that actually represents reality. They could then show the simplified version so that we can actually see what is going on.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#524Flight. How can a plane fly when it's thrust to weight ratio is less than one? It's like, if you can produce 10 pounds of thrust, who would look at that and say "ah ha, we can use this to keep a 100 pound machine miles in the air indefinitely"? I understand flight from a mathematical point of view. I've actually read a few books on the subject, and I could explain how flight works to someone. However, I'm still fishi…
The 10 pounds trust is used to overcome the airodynamic friction, when the plane is in high speed. Because the "way" around the wing is longer on one side compared to the other this create a lower pressure on one side, and higher on the other. This pressure both lift and push the plane up. If there was zero friction you would hold the plane up with zero thrust ;) I build this at school, using the same principle: http…
See my question here: https://news.ycombinator.com/item?id=22993460
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#525Earlier quoted context omitted.
OK but this implies that you'll have to know beforehand what a result will look like. Which kind of beats the purpose of a general purpose computational device.
No it doesn't. You know that the result of the computation for an individual qubit will be either 0 or 1 (otherwise it would be useless -- measuring only gives you one bit of information), so you construct the system such that after the computation is done each qubit will be aligned with the |+z> or whatever axis. The key point is that you have to be clever about how you construct the system for a given QC algorithm,…
OK but we're back on square one. If you can't read info from qbits without breaking the state of the whole freaking system then what exactly is that you reading? Doesn't the alignment info collapses superposition?
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#526The Coandă effect [1] and how it applies to plane wings and sailboats.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#527Abiogenesis. I understand that this is not considered understood but I'd be interested in hearing a qualified scientist talk about how we get from "dumb" matter to self-replicating, goal-driven matter. The closest I've ever heard anyone get (in a personal conversation) is that chemistry is about transformation, so "dumb" matter isn't really dumb in the sense that it's static. Still lots of hand waving to get from bak…
This question interests me as well, and I've done some thinking about it over the years. In particular, what I'm interested in is a hypothetically simplest object that can reproduce in a solution of simpler components, along with some differentiating characteristic. For example, maybe you have toroids that pick up particules, grow the torus until its too big, and then splits - and the ends of both halves click together, forming a total of two toroids. Another characteristic that very simple life must have (I believe) is some level of circularity in the sense that the element is an "accumulation of experience" - we might say a reduction of its environment. In the same way Schordinger was interested in life thermodynamically[1] I am interested in speculating about the simplest possible mechanisms in the beginning. (NB I'd expect none of these very simple machines to survive to present day - in fact, I'd imagine there to be several generations of early life, each obliterating/consuming/sublimating the ones before.)
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#528Why bicycles stay upright. For every authoritative-sounding, in-depth explanation, there is an equally plausible, yet conflicting and contradictory alternative.
Two conditions are necessary for a bicycle to remain upright (at least with most riders.) One is gyroscopic forces. Ever picked up a spinning hard drive? Notice that it feels strangely hard to turn in some directions? Same idea. The other is the feedback loop consisting of the bicycle and its rider. If the bike is stationary, it's hard to keep it upright because you have no assistance from gyroscopic forces. At low s…
That is indeed one of the authoritative explanations, and in a few seconds of ad-hoc search we may find at least two refutations from authoritative sources.
For example, gyroscopic-forces-as-stabiliser don't need the Schwab paper's "ton of math" to be undermined. A simple counter-rotating wheel was used empirically at Cambridge to show as much, alongside notes that gyroscopic forces are relevant to the dynamics of a loaded bicycle, but misconstrued; far from assisting to hold it upright whilst ridden, they induce instability at the beginning of a change in direction, and more so at speed, a phenomenon (counter-steering) familiar to cyclists and relied upon by motorcyclists.
Then there's a simpler observation that can be made: people have to learn to ride a bicycle. The fact it stays upright when rolling unloaded, but not when loaded, is indicative of how small the gyroscopic effect is, not how significant it is. Ergo, that argument would suggest, it is tiny shifts body position that contribute all of the stability.
And then others, proposing further explanations, etc etc ad nauseum.
I have come around to the view that in fact they don't stay upright, and they are almost always falling over, but in a many-branched configuration of the universe our observer effect sends us preferentially down the vanishingly unlikely path where they didn't, and there are an uncountably many alternatives of Me that have nothing but knee scars to show for it.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#529Earlier quoted context omitted.
> Masks are for keeping your own particles from spreading far, not the other way around. Masks are for keeping your own particles from spreading far AND for lowering the probability of virions found in the environment from entering your respiratory system. Masks lower the probability when all other variables are held constant. If someone thinks wearing a mask grants invincibility and in turn chooses to increase their…
> Masks are for keeping your own particles from spreading far AND for lowering the probability of virions found in the environment from entering your respiratory system. Both of you may be correct. I think the person you responded to may not have been precise in their framing. I suspect that you had N95 masks in mind when you wrote masks, which doesn’t negate the point of the person you responded to, if they had surg…
Surgical masks do provide some level of protection against virus droplets and aerosol for the wearer they just are not as effective as N95. Even a teacloth or a scarf wrapped around your face will provide some level of protection to the wearer from virus particles entering their mucus membranes.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#530Lagrangian and Hamiltonian mechanics. That is usually presented in a very mysterious manner. Also I think most engineers do not get taught these.