There is no centrifugal force

Hi,
why do you feel the push in carousel? Or when you are in car turning and you feel pushed on some person which can feel pretty awkward. This is all because of centrifugal force right?

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YOU have been living in a lie

Your whole life was lie if you ever thought that there is something like centrifugal force.

So where is the problem? What causes us to fly from circle? There are three forces acting on you on carousel, gravity of Earth, the bench up so you do not fall through it and also towards the middle so you do not fly away. But still you feel the push from the circle, why if there is no force?

Your body wants to stay in the movement (it has some inertia) which is straight in direction and also in speed. This is Newton’s first law. But it does not because the bench goes in circle and you hold it so you go in circle too but your body does not want to do it so it would rather fly away in straight line which would be tangent to the movement. 

Above you can see that the line TP is what your movement would actually look like relative to the circle which is the carousel.

At every point of the movement you want to go tangent to the circle but you are holded by the force which has the tag of centripetal force. This is just a tag, all kinds of forces can be centripetal, gravity for orbits, friction of wheels for car in turn, ball on string or the bench of the carousel on which you are sitting.

Lesson: do not use the word centrifugal force anymore, it is not there and laws of physics would not work if it would be there.

Check out the video below showing when the speed gets way too big and the centripetal force simply is not able to hold it together anymore (here the centripetal force are the bonds holding the CD together):

Dragallur

Thanks my physics teacher!

Gravitational waves

Hi,
before I start to write about gravitational waves, let me explain how electromagnetic waves work.

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Electromagnetic waves are just light which we see from candle for example. The thing is that in such a candle atoms oscillate and in the process of burning electrons are jumping on more energetic levels, orbitals. When this happens they want to go back right away, so they emit photon and fall back on the lower orbital. Such a photon then travels towards you and you can sense it with your eye.

But all of those atoms oscillate because there is huge temperature in the candle (800°C). They move back and forth creating waves of photons because some photons are closer together as the atom moves to the maximum of oscillation. As it goes back the photons are more stretched apart creating the gap in the wave. This is called electromagnetic wave.

If you had really good eye and somebody would walk away from you with candle, the light would not stop but you would observe the light come towards you in wave, in quantum. The frequency would get smaller and smaller but it would never disappear and would always appear with the same luminosity.

Now when you have gravity this can happen too in what is called gravitational wave. Such a wave is a result of shaking with something that interacts with gravity. The problem here is that gravity is such a weak force that you just can not observe it on candle and you need some kind of star.

Here comes two neutron stars which were found to be rotating rapidly around each other. As they rotate they create the ripples in space time, gravitational waves. In 1993 the Nobel prize was awarded to two guys who were able to indirectly observe how this system of two neutron stars was losing energy emitting those waves, they were observed to be slowly getting closer and closer to each other.

Physicists are trying to observe gravitational waves directly with tremendously precise methods using lasers but it was not yet achieved.

Dragallur

Picture is from here.

 

Observing Supernova

Hi,
so what I just found was very very interesting and it is about observing of Supernovas which are those exploding stars or white dwarfs.

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The problem with observation of these very bright objects is that first of all there is not much of them and second, it is extremely hard to catch the start of the explosion so we do not have much data about it.

This problem seems to have really awesome solution that is based on nothing else than Einstein’s gravitational lensing.

Gravitational lensing is effect of very massive thing like black hole or galaxy or even galaxy cluster. It can increase the amount of light coming to us or bend the light. So actually when you are looking to star right next to Sun it may appear on different spot than it actually is!

Actually I am pretty sorry but not only that you see everything in past but you see it actually on the wrong place, DAMN! (And if you run it is bluer).

So because of this light bending it can happen that the light even comes from different directions.

The picture above shows how we could observe one event (one supernova type Ia) four times in different time intervals just because it was in huge super cluster which bend the light from supernova so much that it came to us in different directions.

This particular observation was done only by accident when one astronomer was looking at pictures from Hubble and he saw it.

Dragallur

Supernova picture
Gravitational bending

PS: today I have reached 400 visitors!

 

5) Four fundamental forces: Strong interaction

Hi there!
I am back again! I was very sick with great temperatures but now I am alright with idea what to write about so I am bringing probably the last post for four fundamental forces today with strong interaction as the strongest of all forces.

Again on the left I have here proton. There are two parts of strong interaction, first is color force which is the stronger one and it holds particles, like hadrons (particles made of quarks) together. You probably heard of colors of quarks, there is green red and blue (RGB) and in such particle like proton or neutron those colors always have to add up to white color. If it would be antiparticle it would have anti red, anti green and anti blue.

Again on left you can see how these colors add up to white. Well what happens is that there is gluon, particle which is carrier for strong interaction and it jumps from quark to quark and when it touches it changes its color. There is great animation in this video, I recommend to watch it: https://www.youtube.com/watch?v=BNDOSMqGLlg
This color force is extremely strong so it does not let quarks to go apart. It is even that strong that when you break it new quark will be created from that huge amount of energy! Scientist think that right after big bang when particles were really fast and close to each other there was state of matter called quark-gluon plasma which was kind of soup of quarks and gluons. It is hypothetic and it was not yet created in LHC or somewhere else.

There is that second part of strong interaction called: nuclear force. I am not really sure about it, but anyway you maybe wondered why does nucleas exists when protons(+) should repell each other and that is made by particles called pions which are carrying quarks around and they are creating reaction which is attractive.

On the end, pions are particles made up of two quarks but one of them has to be antiquark so they looks like this:
There are three types of pions and those are Pi+, Pi-, Pi 0. Their life time is incredibly short and they are decaying to neutrinos or gamma rays.

That will be all,
Dragallur
PS: Thanks for your likes and comments

4) Four fundamental forces: Weak interaction

Hi guys!
We are nearly finishing posts for fundamental forces. First I would like to apologize that I forgot to mention that force carrier for Electromagnetism is photon.

So weak interaction is pretty weak but still insanely stronger than gravitation. It works with quarks and their flavors and it is responsible for decay.
Here on left is picture of all six possible flavors of quarks. (There can also be antiflavors). Most of matter in universe is made up by up and down quarks. For example neutrons and protons.
Force carrier for weak interaction is w+ boson w- boson or z0 boson.

I was talking about decay so I will show you how beta decay is made by weak interaction.

There is proton with two up quarks and one down quark. It wants to change to neutron because that particle in which this proton is is not stable.
When proton touches neutrino which is carrying w+ boson, boson will move to proton and change one up quark to down quark which makes up neutron. Neutrino will lose positive charge of boson which means it will turn to electron which makes up beta decay!

For summary I would say that weak interaction is responsible for changing of quarks flavor which is many atributes of quarks.

Well that was quite short but that is probably all.
Dragallur
PS. here are links to previous episodes of four fundamental forces:
https://dragallur.wordpress.com/2015/03/20/1-four-fundamental-forces-prologue/
https://dragallur.wordpress.com/2015/03/21/2-four-fundamental-forces-gravitation/
https://dragallur.wordpress.com/2015/03/24/3-four-fundamental-forces-electromagnetism/

Eclipse, bus ride and theory of relativity

Hi guys!
It is two days since eclipse of sun.
First of all I will just remind you what eclipse is.
So, it is shadow of moon, because of its rare position between sun and you.
Imagine having lamp. It is your sun. Take your hand (moon) and move it between you and lamp. That is how eclipse works.

There few kinds of it. There is full eclipse.
This one on the left is full eclipse from year of 1999. Picture was taken in France. For full eclipse you usually need to go to some specific place which is calculated by some math quys 😀 . Because that is the only position you can change… you can not change position of sun, moon or earth but you can travel yourself.

Here on left is picture of solar eclipse. You can see that shadow of moon is not visible everywhere… only on very small spot (about 250km^2) is full shadow.
There are lots of things that have to work together if you want for example to have full solar eclipse visible from window of your house.
Because moon is 400x smaller than Sun, Sun has to be 400x further away. At same point your house has to point exactly towards sun and at the same moment moon at right distance has to orbit across your point of view when you are looking at sun.
Well that wont happen 😀 .

Because moon is slowly going away from earth and sun is gaining volume, last full solar eclipse we will be able to see will be 600,000,000 years from now.
You can see list of eclipses on wikipedia. Next total one will be March 9 2016. But it will be somewhere in pacific ocean.

Anyway, two days ago I was in bus by the time when eclipse was seenable. Luckily i was sitting in back seat from which you can see huge part of sky. Well I forgot to take some kind of black glass so I saw it for few seconds before I was too blinded, hope nothing happened to my eyes. Anyway I am looking forward to next eclipse and I hope that you guys did see it!

Eclipse was very important when Einstein wanted proof for theory of relativity. He was predicting that as huge objects bend spacetime, light will be curved if between sun and you is some object with huge gravitional field. Actually moon has too weak gravity so you cannot really see it but when you have quasar and black hole is between quasar and you, you can see that effect of bended spacetime. It is called effect of gravitational lens. http://en.wikipedia.org/wiki/Gravitational_lens On wikipedia page you can see short video of how it looks like, it is pretty amazing.

Thank you for your likes,
Dragallur