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Longest Lines of Sight on Earth

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Re: Longest Lines of Sight on Earth

#71

Post by coldtea »

seanmcdirmid wrote: post #52
kovek wrote: post #42

Earlier quoted context omitted.

I had this question worded differently asked to me when I interviewed to do an undergrad at Cambridge. If you have a rope that is wrapped around earth and you lift it off the ground as much as possible, and you see that it is 10km above the ground, then how long is the rope? I was not able to answer that question right away, and their hint to draw it helped a lot. I did not end up getting accepted.

It seems like one of those stupid brain teasers tech companies used to ask that are not very correlated with success but act as arbitrary filters.

Yes, because they don't want to measure "success" but knowledge of basic math.

Which is par for the course for an educational institution (and a business one could argue).

Re: Longest Lines of Sight on Earth

#72

Post by mrb »

flaie wrote: post #68
mrb wrote: post #21

And I thought seeing Mont Blanc from my town Le Creusot, France (a 216 km line of sight) was very long... not! Apparently it would only rank 6th from the bottom of this list!

You can see the Mont Blanc from the top of the Hohneck which is almost 250km. The first time when I was a kid, I couldn't trust my parents, it was like impossible to see something that far.

Thanks for sharing. I was curious and checked out the view from Hohneck:

http://www.udeuschle.selfhost.pro/panoramas/panqueryfull.asp...

Re: Longest Lines of Sight on Earth

#73

Post by seanmcdirmid »

BurningFrog wrote: post #70
anyfoo wrote: post #63

Earlier quoted context omitted.

In this case the "arbitrary filter" was filtering applicants to a university for very basic math knowledge, so I think assuming that it's correlated with success at that university is not very far fetched.

Sure, but it also filters for people like me, who have seen this problem at least a dozen times.

Ya, these also can totally be gamed with the right amount of prep.

Re: Longest Lines of Sight on Earth

#74

Post by coldtea »

kbenson wrote: post #32

Mt. McKinley (6.194 m.) What country uses '.' as the thousands separator but speaks English? Or is this someone mixing their native language thousands separator with English? Or is there some weird interaction between country and language that makes this the preferred, or at minimum an acceptable standard form? I'm actually hoping it's one of the latter options, that would be something new to me.

>What country uses '.' as the thousands separator but speaks English?

A better question is: how many non-native English speakers and writers neither know, nor particularly care about the english world thousands separator, and use what they regularly use whatever the language?

Answer: millions.

Especially when they are not writing in English to appeal to English speaking countries, but to appeal to a worldwide english speaking audience using english just as a lingua franca.

Re: Longest Lines of Sight on Earth

#75

Post by kbart »

polymatter wrote: post #38
ianai wrote: post #37

Earlier quoted context omitted.

Pretty sure England does.

Londoner here. Nope, we use a comma as a thousands separator. I believe some European countries use a period though.

Most of Eastern Europe and I think Russia use dot as thousand separator. Though it's rare to see these days, it's much more common to simply use whitespace for that, like "1 000 000 000". On the other hand, comma usage for fraction separation is still a norm, for example, 0,99.

Re: Longest Lines of Sight on Earth

#76

Post by kbenson »

hondadriver wrote: post #66
kbenson wrote: post #62

Earlier quoted context omitted.

I guess that makes sense. I was just confused for a bit because I wasn't sure if the height was in in thousands of meters or miles (but if miles, it was odd in comparison to the kilometer distances). I looked up Mt. McKinley and converted the foot rating to meters to confirm that it was indeed thousands of meters, but the process got me wondering if page was mixing locale formats, or whether the my assumption that it…

In mainland Europe we only use the metric system, even when speaking or writing English. Also it is common to stick to the comma as decimal separator and dot as thousands separator when writing English. This convention is independent of the language used. Same goes for date notation, dd-mm-yyyy is used (almost) always. In Windows or Linux for example you can select the English language with Dutch localisation. It's u…

That's a good explanation, and actually what I thought might be going on (which is why I included that example in my original question). It's interesting, because like date formats, it can sometimes be ambiguous without sufficient context. Thanks for the explanation!

Re: Longest Lines of Sight on Earth

#77

Post by kbenson »

coldtea wrote: post #74
kbenson wrote: post #32

Mt. McKinley (6.194 m.) What country uses '.' as the thousands separator but speaks English? Or is this someone mixing their native language thousands separator with English? Or is there some weird interaction between country and language that makes this the preferred, or at minimum an acceptable standard form? I'm actually hoping it's one of the latter options, that would be something new to me.

> What country uses '.' as the thousands separator but speaks English? A better question is: how many non-native English speakers and writers neither know, nor particularly care about the english world thousands separator, and use what they regularly use whatever the language? Answer: millions. Especially when they are not writing in English to appeal to English speaking countries, but to appeal to a worldwide englis…

> A better question is

Actually, I think my question was the more interesting one, because it led to confirmation that this is expected normal use in at least some instances[1]. That was news to me, and apparently the majority of people that responded since they didn't bring it up in their responses.

1: https://news.ycombinator.com/item?id=14862695

Re: Longest Lines of Sight on Earth

#78

Post by kijin »

YZF wrote: post #57
kovek wrote: post #42

Earlier quoted context omitted.

I had this question worded differently asked to me when I interviewed to do an undergrad at Cambridge. If you have a rope that is wrapped around earth and you lift it off the ground as much as possible, and you see that it is 10km above the ground, then how long is the rope? I was not able to answer that question right away, and their hint to draw it helped a lot. I did not end up getting accepted.

The version I got, in a tech company interview, was how much longer would you need to make the rope to allow a cat to go under it. They were basically just look for 2 x Pi x Cat in this case.

That question is ambiguous. If you only need a single cat to go under the rope at some point, you just add a small arch for the cat to walk through. This requires a length of rope somewhat less than twice the height of the cat.

2 x Pi x Cat would levitate the rope by the height of the cat along the entire circumference of the Earth, allowing a billion cats to go under it simultaneously.

You could even make do with no additional rope if you're allowed to take advantage of terrain.

Re: Longest Lines of Sight on Earth

#79

Post by codesnik »

YZF wrote: post #57
kovek wrote: post #42

Earlier quoted context omitted.

I had this question worded differently asked to me when I interviewed to do an undergrad at Cambridge. If you have a rope that is wrapped around earth and you lift it off the ground as much as possible, and you see that it is 10km above the ground, then how long is the rope? I was not able to answer that question right away, and their hint to draw it helped a lot. I did not end up getting accepted.

The version I got, in a tech company interview, was how much longer would you need to make the rope to allow a cat to go under it. They were basically just look for 2 x Pi x Cat in this case.

I'm not sure if I understood you, but 2pi(height of the cat) would allow to make two additional round loops, each sufficient for a very cylindrical cat to go through.

Re: Longest Lines of Sight on Earth

#80

Post by kbart »

URSpider94 wrote: post #61
jdironman wrote: post #53

Earlier quoted context omitted.

Laser powered ISPs anyone? I kid, but is this a possibility?

This exists already, from some pretty serious telecom companies, for distances of a few miles. The problem is that, in optical wavelengths, there's too much absorption and scattering in the atmosphere - fog, rain, storms, smog, smoke - that can disrupt the signal. But, in radio frequencies, this is how the microwave tower communications network works -- it's line-of-sight from tower to tower. https://www.wired.com/20…

Microwave LoS is still widely used to connect cell towers for example. Look at these circular dishes in this picture[1].

1. https://ssl.c.photoshelter.com/img-get2/I0000JUzapOxgCs0/fit...

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