Yeah the fun way Moravec's paradox was explained to me [1] is that you can now easily get a computer to solve simultaneous differential equations governing all the axes of motion of a robot arm but getting it to pick one screw out of a box of screws is an unsolved research problem.
[1] by a disillusioned computer vision phd that left the field in the 1990s.
Selective attention was one of the main factors in Hubert Dreyfus' explanation of "what computers can't do." He had a special term for it, which I can't remember off-hand.
I have seen a very similar (incorrect) argument used to justify the idea of a flat earth. A builder on youtube made the argument (with a similar out of scale drawing of the earth) that if he drops a plumb bob and makes a right angle so he has a straight horizontal line and then goes across that line for a bit and drops another plumb bob, the two lines he has dropped are parallel, "proving" that the surface of the earth must be parallel to the horizontal line and therefore flat and not curved. If the earth's surface was actually curved he argued then the two lines he has dropped should tilt slightly inward towards each other. Which of course they do. The earth is just much much much bigger than in the diagram so the effect is within the margin of error for the measurement he was taking.
As a meta point, our intuition often fails us hilariously when we are dealing with stuff that is out of the scale we have commonly seen in our lives. We joke about LLMs hallucinating but I'm not convinced we are so superior when we are outside our personal "training data".
Ah, but would they actually be parallel on a flat earth?
Say the earth is disc-shaped. Then the center of gravity is only directly beneath you if you're standing at the exact center. You get ever-so-slightly not parallel lines, just like on a round earth.
The fun part of a disc-shaped earth comes as you move towards the sides, and gravity, still pointing towards the center, makes you stand at an increasingly acute angle to the surface. The ground beneath you will then appear like one big endless mountainside, with an increasingly steep slope the further away from the center that you get.
Depends what causes things to stick to the flat Earth. IIRC flat earthers have various explanations for gravity, including the disc continuously accelerating upward; in that case you'd experience the same force everywhere on it.
My math might be wrong, but if we were accelerating at 9.8m/s/s for at least 4000 years (roughly as long as we have continuously recorded history and the minimum time “gravity” has been observed) then we ought to currently be traveling through space at over 1,000,000,000,000m/s.
Now I’m no physicist, but I reckon that might end up violating causality.
Standard flat-earther response is to scornfully deny the existence of gravity. It's all density/buoyancy you see... Gravity is a hoax promulgated by the notorious cabalist Newton, in service to his Illuminati/Papal masters, etc, etc.
I'm considering what flat-surfaced shape you could construct with equal gravitational pull at all points. Maybe something where the center is thin as a point, the edges have a lot of depth, and they curve towards the center either convex or concave. Might run some calculus to figure it out.
That way you should be able design a disc-shaped earth with constant strength of the gravitational force on the whole surface. But it would still have a center of mass (likely lying outside the shape you're describing, in the void beneath the center point), and the direction of the force should still be pointing towards that center, no? So the problem the GP has described, that you're starting to tilt as you move towards the edge, should remain in principle.
I believe the strength of gravitational force would not be constant either, as your center of mass would still have a fixed location, so every point on the disc have different distances to that center of mass (in addition to not being orthogonal to the surface). But maybe it might be approximated with an infinitely long cylinder, so the center of mass is infinitely far away below the surface ?
We actually model the earth as a very large spherical cow. This is approximately the same for most purposes but ends up being more convenient.
P.S. Not a physicist, but my child is studying maths and physics at Uni at present, so I have it on good authority that this is still going on. They told me in their first week one of their classes had a worked example where the lecturer used the phrase "Assume the penguin's beak is a cone".
> I have it on good authority that this is still going on
Do you mean making simplifying assumptions to make a problem tractable? Of course it’s still going on. It has to be, otherwise you just cannot do anything.
> Assume the penguin's beak is a cone
It is impossible to consider the true shape of a penguin’s beak for several reasons:
- you’d need to go all the way down to the electron clouds of the atoms of the beak, at which point the very concept of shape is shaky
- every penguin has a different beak so even if you describe perfectly one of them, it does not necessarily make your calculation more realistic in general.
There is a spectrum of approximations one can make, but a cone is a sensible shape at a first order. It’s also simple enough that students can actually do it without years of experience and very advanced tools.
I totally understand why simplifying assumptions are helpful in modelling and definitely don’t need you to explain that. It also is a bit ridiculous if you think literally about it which makes it something that is fun to laugh about as here.
Exactly. What I take away from that passage is "most of the time it's really not hard to figure out how to be a good person so you're better off actually taking some concrete positive action than spending further time navel-gazing".
Like in TFA. Just be kind to others. Be thoughtful. Be nice to people even when you don't have to be. Try to make life better for those around you. But also be kind to yourself. Don't worry about doing the best thing. Just try to do some good things. Everything will work out ok.
Those are all questions no clock can answer though. They require state from the physical world over and above knowing the current time.
It’s a wild misconception to think that a flooring clock is somehow more late than a rounding clock and it’s if anything an even more crazy misconception to think that a clock can tell you whether something in the physical world has or hasn’t happened.
Yeah so I imagine how this would work to steal people’s funds in this case is to take copyrightable brand assets from someweb3company.xyz. Use them to make a youtube video saying something like “someweb3company.xyz is doing a limited time offer of a free thing. Log in with your wallet details at someweb3company.totallylegitoffer.xyz to claim!” Or some variant on that. Logging in with your wallet gives them permission to steal all your stuff. Because “logging in with a web3 wallet” is actually signing something with your private key. That something can be a json token thing for logging in, but it can also be a transaction and the UX is so god-awful that people often don’t pay much attention to which they are doing and get ripped off.
[1] by a disillusioned computer vision phd that left the field in the 1990s.
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