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Longest Lines of Sight on Earth

beyondhorizons.eu

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Re: Longest Lines of Sight on Earth

#131

Post by titzer »

nerdponx wrote: post #119
btilly wrote: post #25

You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…

How can I use this calculation to convince my flat-earther cousin that he is wrong?

Tell him to watch a f'in sunset. Or the eclipse on Aug 21, which will happen exactly to the second predicted by astronomers. Or look through binoculars at a ship sailing away over the ocean. Or look at the stars rotating around the north/south pole at night. Or fly to Australia and measure the mileage between any two cities and ask him which map is more accurate. Make sure to have a return flight through South America and ask him how long the flight took. Or ask him why low tide is always when the moon is at the horizon. Or ask him what causes phases of the moon. Or ask him why the azimuth of Polaris is always equal to the observer's latitude on Earth. Or ask him where satellites are.

Or ask him not be a dumbass.

Re: Longest Lines of Sight on Earth

#132

Post by pitt1980 »

a12jun wrote: post #13

Surely the longest distance would be, from the top of the highest point on Earth (top of Everest), to the horizon?

Seems like Spain gets a large chunk of the entries due to the geographic phenomenon on a long plain w/o anything to block the horizon plus high peaks on either side of the plain which adds to the horizon

Re: Longest Lines of Sight on Earth

#133

Post by seanmcdirmid »

chrisseaton wrote: post #125
seanmcdirmid wrote: post #73

Earlier quoted context omitted.

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

So why doesn't everyone pass the interview? Either they can't be gamed, or they select for people who can at least be bothered to do the work to game them.

Depends on your resources for prep. Poor kids have less resources for that than rich kids, so they ultimately select for richer candidates.

Re: Longest Lines of Sight on Earth

#134

Post by pitt1980 »

btilly wrote: post #25

You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…

fwiw, this method doesn't seem to predict the list very well

as its not a list of just the highest peaks in the world

longest sightlines also depend on the surrounding topography that blocks or doesn't block a sightline

this seems to account for the numerous Spanish entries on the list, where the large Spanish plain with high peaks on either side, enables you to see from 1 peak to the other, w/o anything on the plain blocking your view

Re: Longest Lines of Sight on Earth

#135

Post by ivanbakel »

jnbiche wrote: post #117
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.

To be clear, they gave you the radius of the earth here, if you didn't already know it by heart? Otherwise, I'm not getting how you could solve this problem (assuming they didn't give you the angle that the arch formed, for example).

You don't need to know the radius of the earth unless you're asked for a numeric answer. The rope is 2 * pi * 10km longer than the Earth's circumference, since its radius is 10km more.

Re: Longest Lines of Sight on Earth

#136

Post by logfromblammo »

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.

It also seems to be a less coherent version of the chicken from Minsk puzzle.

Perhaps it's multiple choice.

  A.  Dreadfully sorry, but I'm afraid I haven't memorized the circumference of Earth.
  B.  What do you mean?  Over the poles or 'round the equator?
  C.  Is that 10 km above at all points on the rope, or just one?
  D.  What's the rope made of?  Jute?  Sisal?  Nylon?  How far apart are the supports?  Young's modulus...
  E.  I don't know about that, but I have inherited a rather large quantity of string in 3-inch lengths...

Re: Longest Lines of Sight on Earth

#137

Post by [deleted] »

btilly wrote: post #25

You can actually work out roughly how far away the horizon should be surprisingly easily. Just use the fact that if R is the radius of the Earth and you are at height h, then from you to the horizon to the center of the Earth back to you is a right angled triangle with one side of length R and the hypotenuse of length R+h. Therefore the distance to the horizon is sqrt(2Rh+h^2) which is roughly sqrt(2Rh). The Earth is…

[deleted]

Re: Longest Lines of Sight on Earth

#138

Post by logfromblammo »

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.

You don't need more rope; you need a shovel.

Re: Longest Lines of Sight on Earth

#139

Post by nprecup »

You can see the sisters from Mt Adams, which is ~230 km away. I'm guessing there are several more of these that the site didn't catch. You can probably easily see Mt Rainier from 300 km+ standing at the right place. How were these determined? It would cool to see a write up on how it was done.

Re: Longest Lines of Sight on Earth

#140

Post by logfromblammo »

titzer wrote: post #131
nerdponx wrote: post #119

Earlier quoted context omitted.

How can I use this calculation to convince my flat-earther cousin that he is wrong?

Tell him to watch a f'in sunset. Or the eclipse on Aug 21, which will happen exactly to the second predicted by astronomers. Or look through binoculars at a ship sailing away over the ocean. Or look at the stars rotating around the north/south pole at night. Or fly to Australia and measure the mileage between any two cities and ask him which map is more accurate. Make sure to have a return flight through South Americ…

All of these strategies are incorrect, as they presume that logic, mathematics, and rationality will have any impact on one who clearly places no value on empirical evidence whatsoever.

What you do is put up $10000 of your money against $1000 of his (10 to 1! You can't lose!), on a bet where the geographical mathematics ensures that you are 100% guaranteed to win. Or something--anything--that can demonstrate with real tangible consequences how being intentionally stupid can hurt you and those around you.

Build two identical UAVs, and run a race between two distant cities. One UAV follows a great circle. The other follows a rhumb line. Discounting adverse weather, the great circle route will win, every time.

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