Why do stars twinkle (and planets not)?

Hi,
I felt so embarassed that I finally had to find it out and now I am writing this short post about it. For few years, roughly, I am studying astronomy yet, I never knew why stars twinkle and planets not. I confess.


Stars twinkle because the light that reaches us goes through atmosphere and atmosphere is not very homogenous – smooth. Air refracts light and there is different temperature once in a while, humidity and so on, I think that lot of factors play the role. This causes the light of star to scatter a bit and creates the twinkling effect.

Planets do not do it. This is great because you can identify them extremely fast on the sky and you do not mistake them for some other bright star. Why? Their light still goes through atmosphere. Because they are not “point sources”. Stars are so far away that even with best telescopes we see them only as points. Planets with simple telescope on backyard already have shape. Some of their light scatters one direction, some the other and it basically cancels out creating nice image. This is also why it is better to go star-gazing in the winter, colder air does not create so much “noise” on the picture.

Dragallur

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Why golden trash bins do not help (modern equipment in schools)

Hi,
(few days back) I am sitting in a classroom, slightly bored by the teacher saying what I heard the day back. After few minutes I am being offered to do experiments alone. I agree with the hope that it is going to be more fulfilling. Instead of getting full access to the laboratory[1] I sadly accept white box, aka trash bin.

https://www.fdgate.com/photo-2/high-school-physical-optical-experiments-box-experiment-box-lens-optical-instrument-physics-experiment-equitment-m-0915.jpg

This is kind of similar, the fact that it is chinese[2] kind of fits the situation since my german is not so good yet.


Such a box contains “scientific” equipment for the study of electro-magnetism. This consists of few cabels, power source, resistors, capacitors, all properly laid on green boards. Function generator, some frequency and amplitude thing, two coils, magnet and some stuff to hold it together. This is probably almost perfect list of things that costs the school hunderds of dollars. I took it with the manual that contained roughly 15 experiments and decided to do one of them. I put components together as it said, found out the thing it said I am supposed to find out, it gave me the formulas to calculate it.. that is all.

So now the rant against these boxes (thrash bins as my host-brother pointed out).
The problem is that such a box with set up equipment and set up experiments does not enhance any creativity in students. Especially building circuits could be one of the cool things where you try what happens when you connect this and that. That is probably the biggest problem, you can just follow some manual and not understand what is going on. Also these components are totally dependant on each other and you can use only this box alone, there is no room for expansion or only limited. Not speaking about the cost, there is another trash bin like this for 800 euro. It had wagon, line on which the wagon could drive, two movement sensors and some things to hold it together and so on. We used it during physics class to demonstrate Newton’s 2nd law (F=ma). It took so much time to set it up, to measure it all to 3 decimal places. Actually it took 90 minutes and we did not get even to the formulation of the law. People were bored and I bet that if you asked half of them what was this whole about they would not have a clue.

This is modern equipment.. and it is useless. If they bought separate components boards to built circuits on, they even have those in the school but they are not used anymore. These days teachers probably think that they can not get better with chalk and a board.

Dragallur

[1] I do not think it would be a good idea to let me there alone though I go there anyway every monday with my host-brother.

[2] I do not know if it is chinese.

Book review 12) Harry Potter and Philosopher’s Stone

Hi,
I have read this book already in Czech and heard it many times on audio and I have seen the movie couple of times. Now in Germany I have finished it in German so I decided to leave it a review here. Of course everybody knows Harry Potter so I will make it little bit different.


Rant against Qudditich.

Despite the fact that the game is awesome, its rules do not make any sense. The obvious part is the snitch which gives 150 points and ends the game. There is no point in catching the snitch if the difference between your team and the other one is more than that. Viktor Krum in the national game in the Goblet of Fire for example, catches the snitch and they lose, good job 😀

Rant against Defence against Dark Arts.

While whole Harry Potter series shows us extremely low number of spells which part of are completely useless, Defence against Dark Arts is the best joke. Most of the time they are actually learning about some random creatures and how to fight with them or what is their weakness (this is not what happens in Philosophers Stone) while in 6th year you will learn how to apparate anyway, which is basicall,y how you can escape anything. There might be something said in the upcoming movie about magical animals so we might find out that it is actually useful a bit.

Rant against other stuff.

Somebody killed unicorn, very strong animal which is extremely fast and its blood has unique attributes. What are we going to do? Send bunch for 1st year students, dog and guy who is not allowed to do magic!
Did Hermione, Harry and Ron really thought that it is good idea to go after Snape/Quirell? They must have known that teacher would be able to wipe them out in matter of moment from the Earth’s surface.
The points for the Cup kind of lost most of its meaning after Harry, Hermione and Ron getting 160 points and next year Ron and Harry getting each 200, people would really hate Dumbledore for doing this (not mentioning the 250 in 5th year).
Quirell could use Avada Kedavra on Harry right when he came to the mirror instead of talking about stuff. Or use Legilimence or use Imperius to get the information, not so hard really..

I like this book still of course, though I have read or seen it so many times that I just can not unsee some paradoxes that are there.

Dragallur

Eating the spiciest natural chilli

Hi,
last Sunday I was at neighbors with my host family for dinner. We ate some pumpkin soup and then I noticed these nice small peppers piled up in the bowl. Already I heard that it is not good to put them in your food so I decided to take it as challenge and take one. People at the table noticed and warned me that I probably do not want to eat it. I was soon persuaded not to take it and rather wanted my host brother to try it and see how it goes.

Yup, this is what it looks like.

“These peppers are the spiciest natural growing peppers.”
“Oh, ok then.”

He said that he is going to split with me. I finally agreed and stuffed half of the pepper into my mouth with some milk next to me and bread with thick layer of “Philadelphia”

https://i2.wp.com/groceries.iceland.co.uk/medias/sys_master/root/h8e/h01/8830465802270.jpg

This is called lifesaver.

After few bites it started to burn a lot. It is quite nasty but the real pain came when I swallowed for the first time. When it hurts in the mouth you can just calm it with bread as it touches the sides of your mouth but when you throat starts to burn it is way more difficult. In something like 15 minutes it was over. Not so much because of pain but simply the pepper, I cried a lot but hey it was quite interesting.

If you decide to try it out, there is one thing to keep in mind. The pepper is going to burn more than one time, actually it might burn three times.. you will know what I mean after you eat it 😉


Anyway there is a chart called Scoville scale, I thought I already wrote about it but then could not find it so here you go.

Spicy peppers have inside neurotransmitter called capsaicin. It fakes your feeling as it bounds on the nerves that are responsible for you to experience heat. Capsaicin is not solluable in water which explains why it wont help you to drink it when you eat something spicy. Milk is better and dairy products generally help. HCl of course helps too.

Capsaicin itself has 16 million points on Scoville scale which is about 8 times as much as the spiciest pepper which is right now Carolina Reaper with individuals well over 2 million. The pepper that I was eating is 1.5 million almost (which is average) and it is called Trinidad Scorpion Butch T Pepper.

Dragallur

Jerks are even in physics

Hi,
the title is a pun. There are probably jerks yes, but what I want to talk about is physical unit[1] called jerk, it is named like this because jerk not only means, idiot or stupid, but also to move suddenly, because of surprise.


It will be nice, if we first recall that derivation describes the rate of change of something. For example, speed is the first derivative of position because speed describes the rate of change of position, the higher the speed the more position changes!

{\boldsymbol {v}}=\lim _{{\Delta t}\to 0}{\frac {\Delta {\boldsymbol {x}}}{\Delta t}}={\frac {d{\boldsymbol {x}}}{d{\mathit {t}}}}.

1st derivation of position “compared” to time

In the picture above you can see how speed is defined compared to position (x) and time (t). It is its derivative as I said before. Now of course you can define something, that describes how velocity changes over time. That is called acceleration.

\mathbf {a} ={\frac {d\mathbf {v} }{dt}}={\frac {d^{2}\mathbf {x} }{dt^{2}}}

Again, “d” simply means derivation and when it is “squared” it means that you need to derive it twice. Acceleration describes, how velocity changes over time.

This is all you might need for daily life. Of course though, scientists defined next derivations, the change of acceleration in time is called jerk. The change of jerk is called jounce the change of jounce is crackle, next follows pop and then possibly lock, drop, shot and put. The SI units of all of these time, position related things are similar. With each derivation you add one to exponent of time.

v=m/s¹
a=m/s²
j=m/s³

and so on..

Just to remind you, if you have lets say “pop”, which is 6th derivation, of 10 m/s^6 you will have a tremendous speed extremely fast. From this next equation it should be pretty clear:

{\displaystyle {\vec {r}}={\vec {r}}_{0}+{\vec {v}}_{0}\,t+{\frac {1}{2}}{\vec {a}}_{0}\,t^{2}+{\frac {1}{6}}{\vec {\jmath }}_{0}\,t^{3}+{\frac {1}{24}}{\vec {s}}_{0}\,t^{4}+{\frac {1}{120}}{\vec {c}}_{0}\,t^{5}+{\frac {1}{720}}{\vec {p}}\,t^{6}}

The power of the higher derivations is that the exponent does extreme changes in a moment. r is the position, v speed, a acceleration… p is pop and t is time.

This is probably not used much, if at all, even in engineering.. but hey, fun!

Dragallur

[1]It is not a unit. It is physical quantity or something like that. I do not really know how it is called in english.