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!

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”!

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
putstr: 
    ld a,(hl)
    or a
    ret z
    call putchar
    inc hl
    jr putstr

main:
    ld hl,#MsgHelloWorld
    call putstr
    halt

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

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

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

;subroutine to print inline strings
putstr_imm:
    ;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
put1:
    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
put_ret:
;restore the stack pointer which point to the code after the string
    ex sp,hl
    ret

 

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.

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!”

 

Nobody saw this coming

Nobody saw this coming.

I don’t know how all of this began and when. Trump was reelected with a surprising majority. Or maybe before, when flat earthers reemerged on the web, proclaiming the earth is flat, based on old unscientific books written long before modern science.

Or how the internet web was beginning to have shitty content of people mutilating themselves or attempting to do all sorts of crazy stuff. You may not know this, reader in the future, but the internet allowed us to share almost everything on cyberspace. It allowed all the computers of the whole planet to communicate with all others. And I’m not even talking about the dark web. Who knows what’s on this and I don’t even want to know. Considering the horrific things we get in the news, one can only think that there must be horrifying stuff beyond imagination. Anyway, enough of that.

There was also all that craze about the zombie apocalypse, but of course, it’s just fiction. There was a tremendous increase of violence everywhere. The radical islamists, the numerous shootings in the United-States, etc. The web was regularly predicting the end of the world each year without success, fortunately. The 4 Blood Moons (just a natural phenomenon), the Rapture (it never happened), the Angel Trumpets (fakes). There was so much conspiracies everywhere that nothing seemed believable anymore. Nasa, Moon landings, ISS, pictures from space, and so many more.
It may not be surprising that if the USA was a culture of fakes, US citizens grew tired of all this fakery. YouTube was merely a vent for all those frustrations.

Many virus appeared after the AIDS virus. Fortunately, with modern science, medicine could annihilate even AIDS. But this …

But all that was nothing, compared to that thing. Nobody knows what it is exactly, but it must not touch you in any way or you’re done (I don’t know for sure). The best comparison I can say is that it’s as if a hacker exploited all the biological backdoors of your body. It may rot you, or transform you into a zombie, or whatever else. Yet, I’m not sure, it’s still matter of speculations. We don’t know all the possible vectors of propagation of that horrible thing.
I don’t know how it looks like. The only thing I know is that your instinct kicks in and you have a feeling there is something horribly wrong going on. Pretty much like the suspense music when there is something about to happen.

I don’t know how this will end and if the readers in the future will even be humajkhlkgjjhvm   hgljgjhg    helpjgjklgjkghjkg     oi;lkj;ljlj            fdgsfsa54……………………………….

Spinning ball model

If we were to reproduce a spinning ball holding water, we should have gravitation exceeding the centrifugal acceleration (300 times stronger normally).

The gravity (acceleration) holding the water should be: g = Gm1/R².

Since we will scale down the model, we will need to know the limit to where we can go.
We need to convert m1/R² to use density:

density = mass/volume -> mass = density * volume.
volume of a sphere = 4πr³/3
m1/R² = d1 * 4πR³/3R² = d1 * 4πR/3 where d1 is the earth’s density (5.51g/cm³)

On earth and the scale model, the gravity is g = Gm1/R² = 4πGRd1/3

We can see here that the gravity at “sea” level is proportional to the radius (other values are constants) hence g = kR where k = 4πGd1/3

The centrifugal acceleration is also proportional to the radius: α = ω²r

To not fling everything in space we need to have g ≥ α, or kR ≥ ω²R or k ≥ ω²

So the rotational speed limit doesn’t depend on the radius. This means that we can make a model small enough for experiments.

The limit for the rotational speed is 1.24 mrad/s which is 17 revolutions per day.