Globe earth and the horizon experiment

For a person with eye level at 6 feet, the horizon would be 0.0419° below eye level.

To do an experiment to test this, we need a way to measure very small angles. A very cheap and easy way is to use an ordinary ruler.

Let’s take a 30 cm ruler, place it at 57.296 m and voilà! The value in meter gives almost exactly the same value of angle in degrees within maybe 0.1% error (guesstimate). I.e. the 0.0419° value should be at 0.0419 m.

Next, we need to have a very precise level. An easy way to do this is to have a hose a bit longer than 57m. The hose should start at the reference point and end at the observation point. Both ends will serve as an horizontal reference.

The water level should be at the 0 of the ruler and a telescope should be at the height of water at the other end.


While you can rent a theodolite, not everybody is familiar with this and its principle of operation may not be recognized by flat earthers who will say most probably that it’s a free mason instrument.

This experiment is very easy in principle and works with easy to understand concepts, and it shouldn’t cost an arm and a leg. It can even be implemented in a permanent installation. Happy experimenting!!!

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The moon and the globe earth

I took this picture of the moon a few days ago. From the angle of the moon, we can see that the sun’s light comes from “below the flat earth disk”. This wouldn’t fit with a flat earth model, for which both the sun and the moon are always above the disk.


Moon around midnight a few days ago


Another flat earther claim is the discrepancy between the continents size.

There is an image explaining this discrepancy, but apparently, some flat earthers are not knowledgeable in photography.

Globe comparison with distanceGlobe comparison with distance

I reproduced this myself with a Canon Coolpix:


Photo of a globe from about 30 cm (1 foot)


Photo from about 1.3 m (4 feet)

On this photo, I zoomed in to bring the globe to the same size as the first picture. We can clearly see the “discrepancy” in size. The images are ‘as is’ from the camera. No photoshop, no fakery, no NASA, no freemasonry.

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Some (unsuccessful) experiments with magnetic bearings

In the confrontation of the globe earth and flat earth models, still believed by many religious oriented people or uneducated conspirationists, the flat earth supposedly doesn’t rotate, because we can’t feel it. It doesn’t occur to flat earthists that the speed of rotation is too small to be felt.

To prove the earth’s rotation, there are several methods; one of them is to use a gyroscope. Commercially available gyroscope available to the great public isn’t suitable for showing the earth’s rotation. They have too much friction and can’t sustain the rotation for very long. Other principles can be used, of course (laser ring, etc.) but are too expensive or inaccessible or hard to understand. There is the geeky Copernitron among other methods.

Ideally a gyroscope should have frictionless bearing and run within a vacuum. Frictionless bearings can be done with permanent magnet arranged in a specific way. There are several demonstrations on You Tube, but nothing was useful for a gyroscope.

I decided to do some experiments with magnets and bismuth. I bough some NdFeB magnets and a chunk of bismuth on ebay. The smaller magnet is supposed to be suspended within the bigger magnet, lined with a bismuth ring (homemade). The picture below shows the bismuth chunk, the two NdFeB magnets in the left, and the bismuth ring on the right.

Here are the dimensions:

big magnet: 3/4″ OD, 1/2″ OD, 1/4″ thickness

small magnet: 3/8″ OD, 9/64″ ID, 1/8″ thickness

bismuth ring: 1/2″ OD, 7/16″ ID, 1/4″ thickness


The bismuth ring was not easy to make; I’m not well equipped for working metal. I made it by melting the bismuth in a 1/2″ diameter mold. I then drilled a hole in the center, working it bigger with a small drill and increasing the drill size. At the end I used a file to get the ring’s final dimensions.


The magnets are magnetized axially. Once the bismuth ring is placed in the bigger magnet, the small magnet can be inserted in the center. When the magnets attract each other, the smaller magnet isn’t suspended in the center; it’s attracted to the side. When the magnets repell each other, the configuration is unstable.

Conclusion: it doesn’t work, yet!

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Water does stick to a “ball”!

Recently, NASA showed a video of an astronaut washing his head. While the guy was bald, this was an interesting demonstration often requested by flat earthers.

Flat earthers say ‘water seeks its level’ and so on. They don’t believe gravity exists, and find absurd that water curves around the earth. As attempts of experiment, they pour water on a ball expecting it to stick to the ball. The experiment simply fails because the gravity of the ball is much weaker than the 9.8m/s² acceleration of the real earth.

For these experiments to have any value, it should be repeated in space.

We know that surface tension is stronger than gravity at human scale. But for the purpose of the argument, water can be shaped into a ball, no matter what kind of force is involved.

Here is the link to NASA’s video below:

Water does stick to a “ball”!

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Assembler trick: inline strings

Quite often, we need to send strings to a computer. Usually, there is a section in your code where you define the message with a label:

;string is terminated with null
MsgHelloWorld: .asciz "Hello World!\r\n"

;subroutine to print strings
    ld a,(hl)
    or a
    ret z
    call putchar
    inc hl
    jr putstr

    ld hl,#MsgHelloWorld
    call putstr

With a bit of extra code, we can make some code with embedded strings.

    call   putstr_imm
    .asciz "Hello World\r\n"

    call   putstr_imm
    .asciz "Hello World again\r\n"

;subroutine to print inline strings
    ;this exchange the stack pointer (SP) with HL
    ex sp,hl

    ;at this point, HL points to the code after the call,
    ;but we placed data instead, terminated with a null.
    ;So we skip the data while printing it. 
    ;When done, normal code follows
    ld a,(hl)
    or a
    jr nz,put_ret ;if null detected we resume code
    call putchar ;else we print bytes
    inc hl
    jr put1
;restore the stack pointer which point to the code after the string
    ex sp,hl


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Can a rock reflect light?

Many flat earth advocates mention that the moon emits its own light because rocks “don’t reflect light”.  I’ve done an experiment.

Here’s a decent rock. Not black, not white, just a reasonable gray.


The experiment setup: a white melamin board as screen, the rock, and a laser pen at right directed at about 45 degree on the rock.


We don’t see much reflection on this picture, since the flash was used.


Now, without flash, we clearly see a diffused reflection.


So the moon reflecting the sunlight is plausible.

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AVR Man and Wasteman

For those reading my previous post, I’m still alive! (And human!)

While I’m tinkering with various processors, one of my favorites is the Atmel microcontrollers. A while ago, they had some comicbook style hero called AVR Man and his nemesis Wasteman. I came up with an amusing story here. If I was good at drawing, I’d make a comic strip:

1st picture:
Wasteman: “Hey, Batmel! There’s a contest for (something about microcontrollers)”

AVR Man: “It’s AVR Man, don’t forget this, Wasteman!”

2nd picture:
At the contest:
Wasteman: “Sure, with my old NMOS Z80, there is no way I’m gonna lose.”

AVR Man: “That’s what we’ll see, Wasteman! I’m participating too!”

3rd picture:
During the contest:
Wasteman: “Dammit! Now the battery’s dead!”

4th picture:
(Wasteman attempts to cheat by charging his dead battery, but it’s not allowed in the rules)
Wasteman: “But I’m not giving up this easily… A quick charge and I’ll make it to the end.”

5th picture:
(caugh red handed by AVR Man and contest officials)
(could use some shadow effects to make AVR Man look like Batman)
Wasteman: “BAT… er… AVR Man!”

AVR Man: “I’m afraid that your cheat was discovered, Wasteman!”

6th picture:
AVR Man: “Fortunately, it’s just a contest, otherwise, you’ll be convicted…”

AVR Man: “of battery charge! Ah! Ah!”


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