How airplane wing really works.
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Ask HN: What scientific phenomenon do you wish someone would explain better?
91–100 of 839 posts
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#92Reactance.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#93The connection between elementary particles and group representations. I get the math, I just don't see in what way it corresponds to reality (i.e. in addition to being a bijection).
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#94I find most explanations of the Equivalence Principle that lies at the foundation of General Relativity to be very lax. To wit, the idea is that you cannot distinguish whether you are in an accelerated frame or in a gravitational field; alternatively stated, if you’re floating around in an elevator you don’t know whether you’re freefalling to your doom or in deep sideral space far from any gravitational source (thoug…
The elevator car is a thought experiment that draws attention to the equivalence in sensation of acceleration on one hand, and being in a uniform gravitational field on the other hand. As you correctly point out, this particular thought experiment breaks down when you consider that all of the gravitational fields that we are accustomed to are non-uniform, and have apparent tidal forces.
The real principle of relativity is a bit more subtle (sometimes called the strong principle): that the effects of gravity can be explained entirely at the level of local geometry, without any need for non-local interaction from the distant body that is generating the gravitational field. To describe the geometry of non-uniform fields, we need more sophisticated mathematical machinery than what is implied by the elevator car thought experiment, but nonetheless, the elevator example is a useful launching point for that type of inquiry.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#95Why a flat earth is impossible.
Gravity. Gather enough stuff, and you end up with balls (unless you spin things really fast).
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#96Orbital mechanics
Two words: Scott Manley:
https://www.youtube.com/results?search_query=scott+manley+or...
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#97Flight. Apparently "air flows faster on the top side of the wing, lowering the pressure" is an incomplete explanation; I even heard we don't completely understand why it works (?!?).
Flight is EXACTLY like swimming except in air and without any component of floating. You're welcome.
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Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#98Why a flat earth is impossible.
If you could make a disc shaped planet appear with a magic wand, and imparted it an initial angular momentum, over time the gravity differential between the middle and the edge would either tear your flat planet apart, or shape it into a blob, and eventually a sphere.
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#99Flight. Apparently "air flows faster on the top side of the wing, lowering the pressure" is an incomplete explanation; I even heard we don't completely understand why it works (?!?).
I've been informed that I'm part of the problem. Comment removed, sorry for the trouble, folks!
That's not how lift works, don't be part of the problem! http://cospilot.com/documents/Lift.pdf
Re: Ask HN: What scientific phenomenon do you wish someone would explain better?
#100Why does time slow down/go faster with movement compared to another object. The well known example that if you travel into space you'd gain let's say 5 years and people on earth 25 in the same time or so. I just don't get it and I can't find any logic explanation. For instance: Two twins who came to live exactly at the same moment in the year 2000 and both die on their 75th birthday at the same time. One travels into…
There are two effects here. One is special relativistic time dilation, and you can derive these effects with very little mathematics (high school is enough). The Wikipedia page has a simple proof, but it's important to realise that this is a result of the postulate that the speed of light is constant. If you travel at 0.99c and emit a photon, it still travels at c, not 1.99c. It's absolutely not intuitive why this should be the case.
The other effect is that time in a strong gravitational field runs slowly.