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Flat Earth General / Re: Is surveying an accurate science?
« Last post by hexagon on Today at 10:48:04 AM »
The level of accuracy you need scales with the problem you have. If you want to measure the distance between to points in a city something like a meter is quite ok, if you want to make an accurate drawing of something, maybe a millimeter is sufficient, a biologist investigating some cell material needs a micrometer scale, and in the semiconductor business you go down to some angstroms.   

If you do standard optics, you don't have to solve the Schrödinger equation for the photons involved, but if you're playing with single photons it could be necessary. 

There is no universal rule for the level of accuracy.
Philosophy, Religion & Society / Re: Am I right or wrong
« Last post by TheLordBarst on Today at 10:35:57 AM »
I didn't even read the OP so I'm going to guess wrong
I have asked about concave refraction here before, but no one has given a satisfactory answer.

What d you mean by "concave refraction"? "Concave" is a property of the lens, not the refraction. The refracted index difference of both sides of an interface determines if the angle of refraction is larger or smaller than the incident angle. But that effect you don't call "concave" or "convex".

A lens as it is used in a telescope or similar instruments is usually a spherical lens, that means it's surface is part of sphere. Therefore it's optical properties are isotropic with respect to center of the lens (the optical axis). There can't be just a vertical distortion. That would only be possible if the telescope as such is not well manufactured or misaligned. But this would be visible in the same way for objects close by or far away.     
Flat Earth General / Is surveying an accurate science?
« Last post by edby on Today at 10:12:20 AM »
This was questioned in an earlier thread. ‘Accurate’ is relative, of course. There is accuracy down to the molecular level, and there is accuracy for the purpose of everyday measurement.

With the help of my late father-in-law’s theodolite, which I am just beginning to understand, I can determine this. The first picture below shows the whole instrument. It was made by Clarkson and co Holborn, and the case says it was inspected 17th April 1962. Incidentally, my father-in-law worked for the British government, travelling to distant places to check the amount of land the government owned or controlled. I don’t know if he was in on the conspiracy, he never mentioned it.

You should just be able to see the bubble in the spirit level, which I set level before the photo was taken. This was done by turning the dial in the second picture. The idea is that when the bubble is in the centre, the optical tube is absolutely level, i.e. on a line perpendicular to the force of gravity, and any object appearing in the horizontal crosshair will lie on that line. It follows that if the horizon appears below the horizontal crosshair, it does not lie on that line. Rowbotham claimed that there were ‘collimation’ distortions in such instruments, but haven’t seen any evidence so far.

The instrument says that each division on the spirit level corresponds to 30''. I looked this up and this means 30 arcseconds, i.e. 0.3 of an arcminute, where an arcminute is 1/60 of a degree. If you think back to schooldays, one degree is pretty small, and 1/60 of a degree much smaller than that. I now need to work out how much difference that division would correspond to over 30 miles.

More schooldays. 30 arcseconds is 0.000145444 radians, 30 miles is 5,280 feet. Therefore to work out how much the 30 arcsecond division on the theodolite corresponds to, I use the tan function to convert the angle in radians to get the opposite/adjacent ratio. Then I multiply this ratio by the adjacent amount (30 miles in feet) to get the error in height. This works out to 23 feet. The question is whether we could live with that. Of course this is not a super high precision instrument. That said, when I levelled it, even a small pressure on the desk, even changing position in the room, caused a noticeable movement in the bubble.

Later on I plan to take the instrument to the North Kent coast where the wind farm and the Shivering Sand fort are a known distance from the coast.


Will you be deleting this thread if you get enough yeses? Otherwise it kind of gives the game away?

I wouldn’t mind butting in now and then when a RE’er was either wrong or being a dick and playing a flatty, but I don’t think I could do it for long, unless I could continually state, “because Sam says so” or ask over and over for proof we aren’t in a RE matrix, when does it become trolling if you are asking us to basically troll?
If I set up an Alt’ that was Inti-like or pasted reams of gobbledegook a la Sandy, would you ask me to represent more the position of this site? If so I have a few questions.

This just illustrated that the author does not have a good understanding of optics.  Denser mediums do not magnify light, the angle of incident between the materials is what causes magnification or contraction.  A convex lens will magnify, a concave lens will contract.  We can confidently discard this quote.

Indeed, it's the shape of the interface between the two media plus the ratio in refractive index that determines the path of the light through the interface. If you have no sharp interface, then the gradient in refractive index and his spacial dispersion determines the behavior of light beams.

By the way, can anyone explain what a "atmolayer" is? Never heard this before...

The best part is the analogy to the laser. The divergence of the freely propagating laser beam is a consequence of the aperture of the laser resonator. You can understand this if you treat the laser beam as a so-called Gaussian beam of zero order. But if you look into the beam, it is imaged by the lens of your eye on your retina and it appears in its original size. Beside, the intensity is too high and you have all glare effects. Just use proper filter and maybe a camera instead of your eye ;-)   
Flat Earth Debate / Re: Guide to Creating a Flat Earth Map
« Last post by edby on Today at 09:20:42 AM »
Common people. You are falling for a classic Tom Bishop play. Muddy the waters and divert attention away from the post flat earth tinking can't handle. This thread isn't about perspective.

I think there are enough people on this forum to measure the angles and direction of the sun from different cities. All observations can be posted in a thread created for that purpose. A rough estimation of distances can be taken to see if it matches what we have been "told".

If nothing else, it would show the inability of the flat earth community to produce a map is due to their unwillingness to be proved wrong by their own observations.
You are so right. Correct. It is all about the accurate measurement of distance between a set of points, and how to project them onto a flat surface.
Philosophy, Religion & Society / Re: Atheism.
« Last post by Jura-Glenlivet on Today at 09:19:22 AM »

 But that's just hazarding a guess.

Great. A guess.

And I said they were mistaken.

 If you go by the Bible, then it is painfully obvious that there is such a contract. The question is how much cherry-picking are you comfortable with?

Maybe God told me there was no such thing. ;)

And that’s the nub of it for me, seriously, when I was in my early teens I figured that if there was a god it was a bigger deal than just going to church every now and then, so I looked.

I read a great deal, talked to Christians and apart from the lack of any consensus on important (to me) things like hell, forgiveness, Hell, is the bible advice or instruction, HELL! I just found/felt nothing.

So then having been a bit put out at the injustice that our (Christian) hell was actually open to all the other religions but the heaven bit wasn’t, I looked at Eastern religions, loved the Buddhism but still nothing, long story short I then read Dawkins and Nietzsche and found my home. 
Now he claims that all lenses have what he calls “collimation” error which is caused by the lens, and makes the horizon appear below where it should, yet he makes no mention of why if this is true the manufacturers dont simply adjust for it, or even why it ALWAYS appears to be below the horizon.
That's the one that puzzles me. Suppose the lens makes every point whatsoever proportionately lower relative to the spirit level than it should be. Then that defeats the purpose of the instrument. You first twiddle the dial which adjusts the angle of the tube, until the bubble on the level is exactly in the centre. Then every point you can see on the horizontal crosshair, will be 'on the level', but this is because the instrument is carefully calibrated at the factory.

Or suppose that nearby objects are level, but distant ones are not, i.e. appear lower than they should be. This would not be explained by the lens, but by a property of the light, i.e. by concave refraction.

I have asked about concave refraction here before, but no one has given a satisfactory answer.
Even of he had a compass or a gyroscopic compass, if you are at what you think to be the South Pole on a Round Earth, you know that have to go North to go back to the coast.

We see from the diagrams of these explorers that they didn't continue in a straight line after reaching the pole. They turned in an angle. Show me an expedition where they continued in a straight line.

If your goal is to cross Austrailia, why woukd you change your angle mid journey?
What the others said. The map shows why. The highway has to cross a large ice with nasty crevasses. Then you have a detour to cross the Transarctic Mountains. Australia by contrast is pretty flat and presumably safe in the middle apart from boomerangs.