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.

 

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The riddle of DARK MATTER! (Part 2)

Hi,
about three days ago I was asked by the writer of “Oopsmymistake” to update about dark matter, so today I decided to write something more about it, here you go.

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Last time I talked about dark matter as stuff that fills about 25% of all matter in whole Universe but we can not feel it and the only way to observe it is by its gravitational effect, for example it is extremely important in whole galaxies.

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Now there are some things that I did not mention because actually there are more things that we can deduce from its behavior.

As I said, it is assumed that dark matter is composed of new kind of particle/s beyond standard model.

Lets assume that this is right, now this particle does not react much as we know, it has to be electrically neutral, otherwise it would react through electromagnetism and we would be able to observe the photons which would come out of the interaction.

Also dark matter still exists which means that it has to have half life at least the age of Universe (top and bottom quarks for example do not form anything because simply they are not here, they have too small half life).

We know that it does not interact much, otherwise it would concentrate in the middle of galaxies and not all around. So dark matter can not interact via strong nuclear force.

Now this kind of hypothetical particle is called WIMP – Weekly Interacting Massive Particle.

It is assumed that the mass of such WIMP is about 10-1,000 GeV which is roughly around Higgs boson and other bosons like W and Z.

The amount of WIMPs with such a energy almost perfectly corresponds to the real amount of dark matter. Also model of super-symmetry predicts such particle with the properties we know now. It is definitely more complicated but it is called the WIMP miracle, while it could be just coincidence.

Scientists think that with this model WIMPs should interact with Higgs boson which would create something we call: “The Higgs portal” because Higgs boson would be the particle through which we would be able to observe whole dark universe (the portal between standard model and dark matter).

Of course particle physicists designed special detectors to detect WIMPs. There are two main way to do that, first is cryogenic, which is the detection of heat made by WIMP interacting with some super cooled element and the second one is to measure flash of light during interaction of WIMP and liquid xenon or argon. Such detectors are buried deep under Earth so that normal radiation does not disturb it.

Approximately in the volume of cup of coffee is always one WIMP and it is assumed that they travel at the speed of hundreds of kilometers per second, which means billions of them whizzing through you every second. Also about 10 interactions of WIMPs happen every year with atoms in your body (this is kind of similar to neutrinos).

Dragallur

PS: if you did not understand some terms I will mention them in next posts: Standard Model, Higgs boson and so on..

 

 

The riddle of DARK MATTER! (Part 1)

Hi,
I can not believe it took so much time to finally write about dark matter since I knew about it such a long time and thought that I should write about it some time.
Now because dark matter has to do a lot with gravity (and only gravity) then I just have to share with you this meme:

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OK, enough fun for now, lets see what this dark matter is.

How did we find it?

Once upon a time one great scientist was born and her name was Vera Rubin. It happened in kingdom (federal republic) far far away, over one big ocean and no mountains. Vera wanted to be astronomer since her 10 years. When she signed up for some school they asked her if she does not want to draw space objects since she liked to draw, this was because in 40s female scientists were not very common.

Finally she was able to start to work and with new age of better telescope she began with huge observation. Most people used those telescopes to look at active cores of galaxies and such exciting places but Vera with her colleague[1] Ford rather observed the outskirts of galaxies and they saw very interesting thing, these outskirts were moving way too far.

As object get away from the thing they orbit (as in our Solar System) they tend to orbit slower.

1. Mercury 47.36 km/s
2. Venus 35.020 km/s
3. Earth 29.783 km/s
4. Mars 24.077 km/s
5. Jupiter 13.050 km/s
6. Saturn 9.638 km/s
7. Uranus 6.795 km/s
8. Neptune 5.432 km/s
9. Pluto 4,666 km/s (oops not a planet :D)

So as you see the orbit speed really decreases, this is because there is lower force of gravity so the planet does not need to be so fast to make these forces equal.

In galaxies this should happen too but it does not!

Now here comes the theory of dark matter which is spread over whole galaxies and there is tremendous amount of it making those stars in the outskirts to go faster than they should.

There are only 4% of ordinary matter the one which we know about a lot.
21% is dark matter and 75% is dark energy as you can see on the next picture:

The only thing we know about dark matter is that it interacts with ordinary matter through gravity. We can measure this and measure how much and where it is, also we know that it does not tend to create some piles like normal matter so it seems that there are no dark matter stars. As Sean Carroll says in his book Particle at the End of Universe, dark matter is a clear example of something beyond the standard model of particles.

Dragallur

[1] At first I wrote collieg instead of colleague, it took me a long time to figure the spelling out even using the corrector in Chrome, I think this will make one of my friends really really happy!

19.1.2016 I made second part so click HERE to read more about dark matter.

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

1) Four fundamental forces: Prologue

Hi again, for fourth time!
I am subscribing some science channels on youtube. SciShow, VSauce, MinutePhysics or Veritasium. They are all awesome and I would like to recommend them to you. Plus I would like to thank to them because I learned a lot of stuff from them.
Anyway, few weeks ago I watched serie from SciShow. There were videos about fundamental forces. Because I would like to write about what i learned on this blog it inspired me to do something similar and try to explain what are those fundamental forces.

This post will only be about what are they together and then I want to talk about them one by one.

So there are four fundamental forces. You could also say basic forces. They have some similarities and all of them have force carriers.
First one is gravitation. It is probably the most strangest one. Gravitation is strange because it only pulls things together. Gravitation is atribute of every particle with mass. It is also crazy weak. Electromagnetic pull between two particles with different charge is 10^42 stronger than gravitation between two particles!

Next one is electromagnetism. It occurs between two objects with some charge. On the beginning of 19th century electromagnetism was created by putting together electric force and magnetic force.

Another is weak interaction. It is (for me) far more complicated i think. It affects very small stuff like quarks. It is also responsible for beta decay. Its carrier is photon.

Last one, also very complicated is strong interaction. Strong interaction is very strong. It is that strong that it can create new massive particles! Again it works on small scale and its force carrier is gluon.

Well that was short overview for fundamental forces. I will talk about them later, one by one.
Thank you for your likes and comments, as I said before, I really appreciate them!
Dragallur
PS. something about radioactive decay is coming!