Scanning fidget spinner

Hi,

Its been about two weeks since I watched this video about rolling shutter and also this video by Matt Parker whom I mentioned last time. Matt was showing the effect on fidget spinner, the new gadget that you simply spin and there is nothing really special about it (except that it spins).FidgetSpinner


Rolling shutter is the effect made by any “picture taking device” (as far as I know). So, for example camera or scanner (in my case). When cameras take pictures, they do so by scanning from top to bottom and saving up line by line of pixels. Similarly, how scanners do it except much faster so that you do not notice it. Scanner on the other hand is slow enough that when something is moving the pictures won’t make any sense. If I would move an object with the scanner, at the same speed it would smooshed across the whole picture because it does not see everything at once, only a thin line.

FidgetSpinner2

Really interesting stuff starts to happen when you spin something so that it goes back and forth (around and around). I did exactly that and it produced for example image above or the ones to the side.

It is interesting how the twisted shapes change with the speed that the fidget is rotating. The fifth and sixth picture are part of the same thing, fidget spinner spinning and being moved by me at the same time. The first one on the collage is spinning really fast, the second one not so much the third one is changing directions and the fourth one is really slow which makes for quite “solid” fidget spinner.

I recommend to try this at home, great and easy “experiment” (of course unless you do not have fidget spinner, then I do not recommend buying (life at stake)).

Dragallur

Swap the numbers

Hi,
I am reading a book from Matt Parker now. It is called “Things to make and do in the fourth dimension” and the ~200 pages that I read are quiet amazing. The author is also YouTuber and it seems that he mostly does “Standupmaths” which is cool channel. I got inspired a bit and created this game that I started to call “Swap the numbers”.


I was thinking about battery on my phone and how it is going down and that it would be interesting, if the first and second number swapped with the first after subtraction of 1,2 or 3 or more percent at a time. I wrote down bunch sequences, beginning with 100 and going down by one digit numbers.

It is not finished since I want to find a way to predict how these sequences form and I have not figured it out yet. I will give an example and then show why this game is so peculiar.

Let’s say that we subtract the number four, that is the one that I started with:

100 (subtract four) 96 (swap both digits) 69 (subtract four) 65 (and so on…) 56 52 25 21 12 8 80 76 67 63 36 32 23 19 91 87 78 74 47 43 34 30 3 -1 10 6 60 56 65 61 16 12 21 17 71 67 76 72 27 23 32 28 82 78 87 83 38 34 43 39 93 89 98 94 49 45 54 50 5 1 10 6 60 56

If you quickly go through these numbers you will find out that they repeat. When the “10” appears for the second time it starts to repeat. (I also forgot to say that if there is negative number it will act as positive on the “swap” step.) For some reason, many of these “constants” that I start with, end in lapses of “tens” meaning that after “-1” there is “10” and then that is the cycle until new “10” appears. First few numbers have the length of the cycle or lapse “36” or “12” and so far, there seems to be only “1 and 10” as constants that will pull it down to zero. (Also 100 but that is trivial and I have not checked some that could be obvious.)

I have made a program in Delphi 7 to write for me all the numbers for any given constant, that is useful but I will still have to consider the mechanism itself to start to understand it.

Dragallur

I have 420 likes on FB and it is completely useless

Hi,
so today I reached 420 likes on my Facebook page. Page that connects directly to this blog. That is almost two times as many followers on the blog itself, after more than two years that is certainly not much but I am surprised how I got those likes on Facebook and how pointless they are anyway.

420

It says that I will soon reach 500 and that I should give them money so that I reach it sooner.


Since I do not post very often here, I am not preparing the posts very long time (like today), I do not get many more followers on WordPress. Most of the views come from some searches on Google and somehow people tend to be very interested in this post because it has about 7 or 8 times as much views as any other one, exactly 1,066 as of 17.7.2017. I guess most schools in USA learn about HClO4 and HClO in winter and that is why I have most views in that time of year even though it was such a long time since I wrote the post.
So, I have got 420 likes and it is completely useless. Why? Because when I share something on the page most people do not even see it on their “walls” (yes, I have an option to “market” my post for money so that more people see it which is completely absurd). Anyway 420 is a number that has something to do with cannabis and it is 42 times 10 which is nice.
420 is these numbers multiplied together: 2;2;3;5;7. Those can be accidentally also written like this:
a_0=2
a_n=a_(n-1)+ceil((ceil(√(n-1.5))^2)/3)
That took me at least half an hour to come up with. The function “ceil” takes the number and rounds it up. I hope it creates the numbers correctly. Well that reminds me that you can create a game from this. I am going to do that in school. Just pick few numbers and then try to write either sequence or equation that fits it. That is actually quite endless game with lot of possibilities and variations. Maybe one could say that they will use only exponents for example though I think that it is much easier with all those other fancy functions that make the numbers “nice” like rounding up.
Well I might try another number another day.
Dragallur

Why are cells so small?

Hi,
ever wondered why you have to use microscope to see cell? Well cells are small but why?

There is a simple geometrical reason for it and it has to do with volume and surface area. First let’s take the case of cell being very big and what it would mean for it.

Such a cell would have much greater volume because of greater diameter, that is quite logical, but if you compare it to the surface area (which also increased) the ratio between the two attributes increased, meaning surface area did not grow so much as volume.

Volume (no matter the shape) grows rapidly with the function d^3 where d is the diameter [1]. On the other hand, the surface area only with d^2. So, what this means for the cell is that the surface = the membranes, are going to need to work extra hard to feed and clean up the rest of the big cell. This has some limit and that is why cells tend to be rather small and only viewable with microscope.

If the diameter is 1 than both volume and area are 1. (ratio 1/1=1)
If the diameter is 3 than volume is 27 and area 9. (ratio 27/9=3)
If the diameter is 5 than volume is 125 and area 25 (ratio 125/5=5)

The cell also cannot be too small otherwise the “equipment” (organelles) would not fit in.

Dragallur

Source: https://www.youtube.com/watch?v=wuXSEOKNxN8

[1] Take a cube for example the equation for its volume is V=a^3 where a is the side.

What if the school was a RPG?

Hi,
imagine if one day you came into school and there would be 5 groups in the class. Each one of them had their own character sheet with an information about the character which they are in control of. You would pick the name, place in the world and what does he or she does. Some information might be chosen by the teacher if it would be needed, like the time in which the person lives.


I am thinking up some random rules that I thought would be interesting.

For example, the character would have certain amount of energy and it would sleep well only if you would solve some math problems. Teacher has in curriculum to talk about how the people lived? No problem, it is winter and they need to get clothes (maybe the sellers speak in English) but the groups do not have enough money so they can either teach the seller how to write (because for some reason that is exactly what he needs) or they must find how to get money, maybe by painting pictures about what happened so far or helping design a bow or even build a prototype. Because everybody needs to eat, they will go to forest and learn about plants that are useful for eating and maybe even cook a food and decide if the character liked it or not. On the road, they meet a traveler and they need a water from him because it is a dry season, he has it but needs information about the situation in kingdom. Because they are so far away they need to write a letter to their parents about what happened, of course it needs to be grammatically correct. Finally, after completing their quest they can use the time machine and move into different era, maybe they want to meet with people from their parent’s generation or see a tyrannosaurus rex.

My point is, I personally would be so much engaged in something like that! I am not necessarily proposing it as a true model for schools but I find it to be creative solution to many problems in school though some might still stay, what if a kid is not happy with the character or with the style of RPG? (Well not that many kids like the system these days.)

The thing is that it is an adventure, not just sitting in a school and writing down notes, you are living what you are learning and I would learn german if it was either my character lives or my character dies.

Dragallur

 

Should we ban poetry writing?

Hi,
so I was reading a lot of books for my school lately, roughly one a week which was quite a marathon for me. Of course since it is for literature, there are all kinds of books which I read. They were usually published in 19th century because my Czech class is learning about romanticism, naturalism and all kinds of Czech stuff (I do not want to say “weird shit” because that might be simply too offensive :D).


There were certainly good books and I do not even have time to review them (it would be quite boring), for example Pride and Prejudice (I had quite a prejudice against this one), Cosmic songs (best representative of poetry (Písně kosmické)), Wuthering heights and Boule de Suif were quite good.

What I want to get to, is poetry. From my perspective poetry does not really have much of a value, which should probably teach me something when I think that.

You know, when I read poetry I feel kinda dumb. My Czech is on quite fine level (as a native speaker) but it can so easily happen that I do not understand the poets, why would anyone write that if they can just tell the story in novel? Then, next level comes with poems in English that are FILLED with non-existing words, you will quickly accustom to “thou” and “thee” even though people probably seriously used it few decades back, but then it will step quickly on next level. I bet that if you copied them to Word and tried to check for grammar mistakes, your computer would break down.

Now lets go back to the lesson. I am pragmatic person, of course I would reduce it, so that it becomes more easily understandable but I know that for some reason lot of people like to read that stuff, people that definitely understand languages more than I do.. maybe they are just sentimental!

The thing is that I would gladly reduce all grammar in any language, even better, make a global language that does not have any exceptions, has 3 tenses and no y/i (that is really annoying in Czech).

Again people who actually understand this stuff and have the feeling for languages disagree with me, I have tried more than once and always got skeptical looks saying basically “you are cancer, go home”.

So it seems I should be more skeptical of my radical approaches to things regarding simplifying languages, as of now I am not in the position to change it, when I will be there will be some need for education. As with the poetry, I am almost done with what I have to read anyway!

Dragallur

PS: It might happen that I do not post next week because I am going to Berlin (and then Czech Republic!)

How slow can slow motion get?

Hi,
ever been wondering how slow can slow motion get? If you hang for a longer time on YouTube eventually you might notice the channel The Slow Mo Guys or Smarter Every Day, both of them feature „quite often“ slow motion videos, meaning videos that have many frames per second (FPS). If you then slow the frames down you will get very slow video showing detail of whatever you are filming, whether it is flame tornado or AK-47 under water.


The slowest I ever watched is this one: https://www.youtube.com/watch?v=xbuvcQrAOSk

It has FPS of 343 915. That is a lot and in the video they are cracking glass container with high temperature difference. The video is so dark because in the short amount of time, not much light can get into the camera and that is often the limit for such high speed filming. You can also see that even though the video is so slow, the crack still propagates through the glass in surprising speed.

MovieBut this is not the limit, you can go much slower but it requires whole different technique. With 1 trillion FPS you can actually see light traveling through medium, it looks pretty impressive but how can it be done?

The scientists use a laser to lighten up what they want to take photo of. They take a 1 dimensional pictures, basically line of pixels[1], couple hundred times and then with a smart mirror they move along the object that they photograph. This technique is called femto-photography and the event on stage has to be performed many times before one gets the picture.

To put it in different words, you take a titanium-sapphire laser. Lighten up the object for a short time. Capture the photons that bounce back to you. Repeat over and over again and with some mathematical reconstruction techniques you got your result:

https://www.youtube.com/watch?v=qRV1em–gaM

Interestingly enough this kind of device is able to see around corners and has very high potential for use in many technical fields if we are able to make it work faster and in smaller devices.

Post based on TED talk.

Dragallur

[1]It is not really line of pixels as you can read in the next paragraph. You are getting back couple of photons and through the mathematical analysing you get the picture.

Gif source. http://web.media.mit.edu/~raskar/trillionfps/

 

How do bearings lower friction?

Hi,
The first time I really encountered object with bearings and was wondering about what they really are was about 3 years back when I was on inline skates with a classmate. There was a nice long and smooth downhill and we both drove down without much beforehand added speed. Soon he was going way faster and was still moving many seconds after me. At that point when we started to talk about it, I thought than my inline skates do not have any ball bearings, which I now think is not true, he only had clean ones since his skates were new. Probably without bearings the skates would not work.


Ball bearing. See how they do not slide, they rotate.

Ball bearings are small balls (often from metal) enclosed between two spaces that are supposed to rotate, for example on some axis. It is possible to just leave the two surfaces touching but then they just rub against each other which causes high friction. The important part is that the balls as you can see on the left, rotate, they do not slide and when circular object is only rotating instead of sliding it does not experience much of a resistance. Try it yourself. Take a pencil and toss it across table so that it does not start to turn (parallel with the direction of the movement). Remember the distance where it got and try the same thing but this time perpendicularly and see how far it gets, that is exactly what the bearings are doing.

There are lot of types made for different purposes. Since the bearings have much lower area with which they are touching they do not distribute pressure so well, also they might need cleaning often or lubrication. In fidget spinners you will of course find bearings. The ones that spin very long time are the ones with ceramic bearings.

Dragallur

Habitable zone of a star

Hi,
habitable zone of a star. Sounds like a comfy place, right? Well it can be. It is at least on (tiny portion of) Earth which is an example of object in habitable zone. Such a „zone“ is important for astronomers, or maybe it’s just important for headlines in newspapers.


Habitable zone in a Solar System based on luminosity.

Habitable zone is an area around star where we, with quite limited knowledge on this subject, think that life could be. The simplest „definition“ is that it’s the area where satellite (such as planet) would be able to sustain liquid water. We cannot be sure of course if life needs it but it is the case for the one that evolved on Earth.

The true habitable zone is something a bit more complicated. The simplest case of a planet would be one that behaves as a black body, that means that it absorbs all radiation (light for example) regardless of its wavelength. This is immediately just an assumption because such a planet does not exist. Earth just as Uranus or Mercury reflect light, the planet’s albedo describes this. Albedo is an attribute telling us how much object reflects light. 0 means that it is a black body and 1 means that it is white body aka perfect mirror.

There are even more factors that one could consider. For example, when planet has thick atmosphere it can sustain liquid water (and life) even further out from habitable zone on the other hand if that happens to planet like Venus which is already pretty close, you have got hell. If satellite orbits with high eccentricity the conditions are again different.

It’s hard to combine all of this together which results in lot of different outcomes depending what model one picks. Estimates for Solar System are between 0.9 or even 0.6 to 1.3, 2 or 3 astronomical units. In most of them Earth is just on the inner edge. These numbers were pulled from Wikipedia.

When we hear in news that a new exoplanet was found in a habitable zone it might not mean much. This news usually come alongside the information that the planet has similar size that of Earth, it’s not like we could travel there or anything, now we are mostly collecting data and learning.

Dragallur

HZ picture: By Habitable_zone-en.svg: Chewiederivative work: Ignacio javier igjav (talk) – Habitable_zone-en.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8462897

Problems that we will have to face

Disclaimer: This is my opinion, not advised by anybody, feel free to comment below.

Hi,

There are two problems that we as humans will have to face. I will write about the two that I think are crucial and only now people start to appreciate them.


The first problem is Global warming. It poses a lot of threats not only to fragile ecosystems but to whole Earth. Some of the effects listed from Wikipedia are: extreme weather, sea level rise, ocean acidification, changes in agriculture, environmental migration and much, much more [1].

Global warming is the first problem that we need to address but in this post, I will concentrate on the next issue on the list. Humanity will eventually die out if we are not able to spread in the Universe [2].

First, we could of course ask the question when we should colonize other planets or even if it is good idea. Let’s take a scenario, when humanity successfully colonizes Mars and at the same time Earth is becoming more inhabitable. At some point, we simply leave it behind, maybe let it rejuvenate without ever learning how to live in a way that does not cause rest of life extinct. What would continue? Maybe we will be able to spread out in the rest of the Solar System and eventually leave it behind. In what state though? And does it even matter if Mars which is right now mostly empty wasteland suffers any damage if it is even possible? Maybe we would change into species that travels the Universe and leaves dead rocks behind? What if we encountered other life out there, would them await the same fate as Earth? We are authors of our own morality and clearly there does not seem to be objective one. Our values change, we are starting to really appreciate our surroundings, the question is, are we fast enough?

Picture of Mount Sharp on Mars, taken by Curiosity rover.

Dragallur

Note: I am aware that there are different things that could happen. I took time today to write shortly out what I thought about one of them.

[1] There are also problems not related to Global warming but are as well very global, for example what are we going to do with plastic.

[2] See also, gamma ray bursts, solar eruptions (big problem but probably no immediate deaths), huge asteroid collisions and other things that would wipe us out.