Neutrinos, the Superstars of particle physics.

Neutrinos are the superstars of particle physics.

Indeed they are the subjects of many news articles and succeed in maintaining the mystery around them which makes us wanna know more about them.

How can such a tiny particle creates so much fuss and excitement about it? What's so special about neutrinos? Why do they play hide and seek with us?

What are they?

Neutrinos are particles of matter. As I mentioned before there are two types of particles:

particles of matter called fermions

particles of forces called bosons cf article...

So, neutrinos are fermions and more specifically, they are leptons.

When were they discovered?

Neutrinos were discovered in the 1930s. It is quite a different story than other particles. They were discovered because of a bug.

At that time people were starting to understand more and more about particle physics.

Electrons wasn't a mysteries anymore, nor were protons, neutrons and a bunch of other particles.

One of their favorite experiment was the b decay (that tells us a lot about nuclear physics):

No, no, don't be like...0.0 what's that...
It's actually super easy to understand. The beta decay happens when a proton p meets and electron e-, those particles annihilate and create a neutron and?… but what is that? Let's take a look at that equation for a second.

One of the most important rules in Physics is that energy must be conserved.

That means that for any transformation, there has to be the same amount of energy at the beginning than at the end.

But here physicist could calculate over and over again, night long, there was always something missing. The energy was not conserved, but instead they realized there were more energy in the beginning than in the end!

JEZZ! Where did that energy go! 'Cause no, it simply cannot disappear!

Wolfgang Ernst Pauli postulated that this question mark should be an extremely light and neutral particle and in 1933 Enrico Fermi named it neutrino (which mean in Italian little neutral one). What a cute story!

The equation was finally completed!

Where do they come from?

Well they don't really come from your garden. Though they are everywhere and probably thousands go through you everyday! Don't worry you are totally safe. :) I'll talk about it in the next part.

They need cataclysmic event to be produced, event that are so powerful that they destroy everything around them.

Such event are Supernova, i.e. explosion of huge stars.

                                                                            Supernova

They are also produced by black holes.

Once they are produced they travel and meet us. They can travel for millions of years without meeting anything!

How can they be detected?

As I mentioned earlier thousands of neutrinos go through you and me everyday. And there's nothing to worry about. Why is that so? Because neutrinos barely interact with anything. They are so small that they go through the empty space between the nucleus and the electrons (pictures).

They rarely hit another particles. Now you must think, fiu, I didn't want to get a neutrino cancer. Well you won't! But the fact they don't interact makes them extremely hard to detect as well.

For that purpose, scientists worked out huge installation that look like big swimming pool hoping to detect neutrinos!

                                                                      Kamiokande

And it worked! They even detected almost ten neutrinos at the same time!

(Most of the time they are happy when they detect one neutrino a week...)

Why are they so strange?

They are strange indeed. Not because they are small. Not because they are light.

First of all some scientists thought neutrinos might be tachyon which means they can go faster than light! It turned out they are not.

But something else make them very interesting:

They change flavour. Basically there are 3 types of neutrinos: electron neutrinos, muon neutrinos and tau neutrinos.

And the weird thing is that an electron neutrino can decide all of a sudden to become a tau neutrino. It's like wearing a pink dress and decided all of a sudden to make it blue.

And no one can explain it so far!

What's so special about them?

If you're not convince yet neutrinos are hella cool, let me explain myself a little bit more.

Neutrinos are particles that we don't  really understand. We know they have a mass, but that mass seems to be smaller than anything we know, same for their energy (it is extremely low).

Beside their flavour oscillation has never been seen with any other particles.

Those particles are still a mystery to scientists. And that's awesome because studying them is going to help the scientific community unravelling some mysteries of the Universe such as the early ages of the Universe...

Sophie incognito

Want adventure?! Let's go to CERN!

Most of you have probably already heard about the CERN. For those who haven't, it doesn't mean Certainly Enormous Reason to Obey. Nah. It stands for Centre Européen pour la Recherche Nucléaire, yes, it's in french. It means European Center for Nuclear Research.

This adventure started in 1954 between France, the UK, Switzerland, Italy, Germany, Norway, and Sweden (now 21 countries are part of it) and billions Euros were spend during those years. Ok...you may think...lots of big words. And now what.

Well, I know humans have walked on the Moon and even sent stuff to Mars. But the CERN is from far one of the most exciting human adventure. It is the largest particle accelerator in the World. Yes you heard me, in the whole world !

Now, you may be like...so, how big is it ?

Well let me tell you right now !

It's a 27 km (16 miles) ring located 100m (328 feet) underground between Switzerland and France.

                                           everything is 100m underground

Like you take a lift to go down there ! And then you can skaterboard for like hours.

                                                 

                                                              parts of the ring

So remember we said that particles are hella small. So why do we need something that is that big.

What is the whole purpose of that gigantic installation ?

Without getting in detail let's take a quick look one of the most famous equation in physics. I name one of Einstein's equations: E = mc^2.

What does it tell us ? It tells us that energy (E) and matter (m) are kinda the same (c^2 is the speed of light squared...but let's forget about it now). So the more energy I have, the more matter I can create.

                                                                  Swag Einstein!

Now the next question is, how do I create energy ?!

Let's take an analogy : Do you feel like you have more energy when you run or when you stay at home watching TV ? I hope you do when you run...okay then you tired...but I mean, when you are running you feel energy right ?

It's kinda the same for particles. They have more energy when they are « running » and by that I mean when they are moving very fast.

                                                                   Run Baby run

So let's brainstorm: if we want to create lots of matter (aka particles) we need lots of energy which we can get by having other particles moving very fast. Here we are. This is the whole concept of the CERN. It is a particle accelerator where particles are accelerated so that they carry lots of energy and this energy can be converted into other particles.

And the particles that are accelerated are..protons. Remember. Protons are particles you find in an atome's nucleus.

Now let's focus on the following point : How can we accelerate particles?

I mean, it's not like we're gonna tell them to run, and then they're gonna run. No, they don't really listen to us... But remember when you were a kid and were playing with magnets. When you bring a magnet close to another one the second one usually rushes to the first one or gets away for in. In both case you created a movement of the second magnet without touching it.

                                                                       This kid got it

At the CERN there are hundreds of huge magnets alongside the ring. Those magnets make protons move faster and faster and faster... And the bigger the ring the faster you can accelerate protons.

Now, we are not really interested in protons since we know them (yes we do). We want to create wierd and unseen particles. So we need to convert the energy carried by those protons into matter. To do so, we are going to make them collide. What happens at CERN is that actually two beams of protons are created, accelerated on opposite direction and when they are ready, they collide producing many particles.

So this is what happends at CERN :

- A proton beams is produced.

-This beam is sent in a first small particle accelerator, then in second...

-Then it is sent to the big accelerator (the 27km one).

-When it reaches the maximum energy, it collides with another protons beam running in the opposite direction.

And this is what we get.

                                                               particles collision

So, Yes, the CERN IS FUCKING AWESOME!!!

                                                     Even Morgan Freeman thinks so!

Next part will be about the detectors at CERN, how they work, and what particles they can detect !

And we'll talk about Neutrinos very soon!

ps: Photos of the CERN were taken mars 2014 when I was there.

Sophie incognito

Why is Physics so sexy?

As you may have understood, those following few words aim to do two things: show how our fascination for Physics is natural, and how to raise that interest. However, let's first focus on our dear Hendrik

Kuldar Leement - Never Quiet

By a dark day of winter, Hendrik went back home and stepping into the darkness of his room, switched the light on. Miracle: and there was light! He reiterated the experiment successfully so many times that he gave up the idea of any divine intervention. He thought to himself: "that is only science!"

Nope! This wonder obviously comes from some very advanced technology, but is far from being science. Where technology  implement our knowledge for our everyday life, science is only concerned by that pure knowledge. For instance, Physics is not going to explain how to make the switch but it will explain how it is working and why the laws of nature make it so that it can be turned on. Enlightened, Hendrik said with passion: "so, it was divine".

Is Science a religion?

Here again the border between what is natural and what is a miracle gets thiner and thiner. Some would even say that Physics and its laws have almost completely erased their religious beliefs leaving room for a rational formalism closer to intuition. However those would have done nothing more than create another God, more logical, more palpable, more human… A 2.0 version of a God.

But the foundation of all demonstration and calculations always lies in primary axiomes and postulates. 

Science is not a religion.

The question is not whether or not to believe in the Big Bang. The aim is not to reach what is called real nor to say what it substantially is but simply to describe what we see. That big boom (we’re naming the Big Bang) Fred Hoyle was referring to, with sarcasm, is nothing more than a cosmological  model aiming to describe the origin and the evolution of the Universe. Yes, a model. One among others. That one working better than others: it is consistent with most of our current observations. The Big Bang is more of a geek equation than a creation at the origine of space-time. At the end of the day, the main goal in Physics would be to find the phenomena that can not be explained by the current model and would lead to a better one. (For sure the dude that finds that would get a Nobel prize.)...And so on and so forth. 

From that moment on, when Hendrik understood the ephemeral nature of our reflexion's base, he couldn't help thinking: "what is our science really worth?"

Physics is beautiful. That's indeed what makes it so sexy.

Let's take an example: rainbows. No one can claim to be insensitive to the beauty of the colors of the light spectrum (not even Hendrik). From the child to the old man, we all are mesmerized by its beauty.

Of course the physicist doesn't always think: "well, a rainbow is a phenomenon of optics that displays a spectrum of light due to the sun shining on droplets of moisture in the atmosphere." He just doesn't. However, be certain that his scholarly contemplation expands by a thousands times his imagination's horizon.

That way, free from any spiritual or metaphysical thoughts, let's curiosity be the fuel to unwrap the mysteries of the Universe and its phenomena; the link between that knowledge and beauty would come naturally. In the end, what matters is our ability to wonder, our ability to keep looking at the world the way we used to do as a child discovering the world around him…

NB: The man on the cover could not in any case be mistaken with our dear Hendrik…



Sophie incognito

Particles, myth or reality?

   If I ask you « How do you know trees exist? » you may answer « Well....because I can see them, I can touch them, I can hear the wind blowing in their leaves. My senses are telling me that this thing we call tree exist». Ok, the truth is that you're more likely to look at me and be like...shut up, you wierdo, do I ask you how you know your mother exist ?! Anyway...

My point is that you experience the world around you thanks to your senses.

Now how do you know particles exist ? I mean not you, you. I know you have other stuff to do in your life than looking for particles, and yes, some people called physicists get paid to do that.

So how do physicists know fundamental particles exist ?

And no, they are no superheros that can use ultraviolet vision to do exciting stuff!

That'd be awesome...the League of Superhero physicists version...

                                                   well, superheros or superheroïnes....

   First of all we may wonder how small those particles are. I mean if those were big enough we could answer by saying that we can see/hear/touch...them...But unfortunately, God, the mystery of the universe or whaterver is bigger, decided that those particles should be small. Like super small, like below 10^(-18) meter which is 0. 00000000000....01 meter (zero dot followed by 17 zeros and a 1).

A nucleus (which is already small) is 10 thousand times bigger than the biggest elementary particle ! It's like the size of a basketball compared to the size of a basketball field !

                                                                         an atom

So we would need some super microscopes to see them.

   The best microscopes nowdays are electrons microscopes and the smallest object they can see must be at leat 10^(-12) m (remember zero dot followed by 11 zeros and a 1). I'm so sorry to come up with the bad news. I hate doing that. Well, it's still a hundred thousand times the size of an electron. So even if you were planing on trading one of your eye and replace it by an electron microscope (I know...who would even think about doing that...), it would still not be good enough to see particles. 

                                        Nice try dude, but u'll have to work on it a bit more                                            

   So basically we are not able to see them. Moreover some particles (not electrons) usually have a very short life time. Not like when you think that you wanna make it 'til 250 years old 'cause seriously that's not even that long...I mean I also do wanna meet my grandgrandgrand children...maybe those ones will finally save the familly honour.

No, here I'm talking about fraction of fraction of second.

For example the tau t's life time is only 2.8 10^(-13) s

Like you don't even have time to begin wanting to think that it's already dead. It's like one day compared to the life time of the universe !

                                                 The tau is like a very massive electron

   And I am not even talking about the mass of those particles. Since they are super small, they are also very very light. The electron is 10^(-31) kg ! The ratio between an electron and a rabbit is similar than that of a mosquito and Jupiter !

   Too much numbers everywhere... All of it is too small for me to wrap my mind around it ! I know.

I mean seriously I am happy drinking my coffee in the morning and meeting my bed at the end of the day...(and knowing about the mysteries of the universe, sometimes..okay, let's keep on...)

   Hopefully all particles are not so shy and snobs. Some of them like to electrify us. I name electrically charged particles...i.e. particles carrying an electric charge. You know it's like when you meet someone who's super magnetic, like he attracts everyone. Here it's the same. There are two charges : + and -, same charges repulse each other and different charges attract each other. Like « opposite attract each other » quote thingy. Well those particles are pretty cool 'cause they bend, and leave traces when the right environment is created. Just like in a cloud chamber !!!!

Yes....I hear you...what is a cloud chamber, is it like the smoking room in a club ?..... Wo wo wo . We're still doing physics folks !

   In 1911 Charles Thomson Rees Wilson a Scottish dude invented the first cloud chamber! Basically it's a box filled with vapor of water or alcohol. When a charged particle crosses the mixture, ions are gonna be formed through its path and leave a trace, just like in the GIF below.

                                       cloud chamber: all the little traces are particles' path

                                            (in the beginning some gaz is being introduced)

HOW COOOOL !

                                                                 #feelingexcited

   That was just the very beginning of particles detectors history.

In 1952 Donald A. Glaser invented the Bubble chamber that kinda work the same with liquide instead of vapor, and in 1968 French physicist (feeling proud!) Georges Charpak built the first wire chamber that kinda doesn't work the same at all....

                                                 particles trajectories in a bubble chamber

And some years after the biggest particle physics facility as we know it today: The CERN!

Sophie incognito

Yes, even Particles have their own history !

   In 1909 two physicists, Hans Geiger and Ernest Mardsen under the direction of Ernest Rutherford made the following experiment : they sent alpha particles on a thin metal foil made of gold atoms and checked how alpha particles would bounce back. I know, who on Earth would wake up and be like, I'm gonna send alpha particles on a sheet of gold... 

                                                               Rutherford experience

Well those guys did and made a breakingthrough discovery : atoms are made of a nucleus positively charged and electrons graviting around this nucleus. You may think, how great...everybody knows that. How else could an atom be. 

  Well untill that time most physicists thought that atoms were like a pudding where negative and positive charges would happily swim around. Too bad for those physicists to realize that positive and negative charges are like cats and dogs. Now, your cat may like your dog, but you got the point right...They don't share the same room. When electrons race around the nucleus (pretty far away) in their own clouds, positive charges are happier cuddling in the nucleus. 

                               illustration of positive charges cuddling....(that dude looks creepy though)

So now, you may ask me... so there's a cloud full of electrons, a nucleus where positive charges cuddle (orgie...lol), so... What's in bewteen ?

Well Ladies and Gentlemen, be ready for the greatest answer ever.... There's nothing. Not like when you open your fridge coming back from holiday and have to make the following sad statement : « there's nothing in my f***** fridge », not that kind of nothing. I'm sure, there's a beer left, a rotten tomato, some left over of chinese food.

                                               Hum....what am I gonna have for dinner?!      

 When I tell you there's nothing bewteen the electronic cloud and the nucleus I mean the void, total void, not even the smallest, slightess particle. NOTHING.

That was something to admitt for those guys. Matter is made of molecules. Molecules are made of atoms. Atomes are made of an electronic cloud, and a nucleus with Nothing in between !

                                                              atome: electronic clouds 

Now we know that matter is made of electrons and a nucleus.

Cool, but let's take a look closer.

What is the nucleus (but an orgie, yes yes, we talked about it before...) or should I ask, what's in the nucleus ? Rutherford -yes that same dude who discovered the structure of atom, some have it all- realized that the nucleus was made of protons and neutrons. Protons carry a positive charge and neutrons are electronically neutral. So here it is. We know a lot about atoms. And we're not done ! We can zoom more ! How exciting, how far are we gonna go. Well, sorry guys, this is gonna be the last zoom for now. So we know that electrons are fundamental particles, which mean that they cannot be decomposed into smaller pieces. However protons and neutrons are not ! They are made of smaller particles called quarks. Those guys however are fundamental particles. Fiou....we're done zooming !

A proton is made of two up quarks and one down quark and a neutron is made of two down quarks and one up quark .

So now we have three elementary particles :

the electron and the up and down quarks.

And this is just a very small piece of the puzzle.

During the 20^th century physicists putting their brains together established the existence of no less than 16 fundamental particles !!!! Plus the Higgs Boson that was discovered three years ago.

Basically there are two kinds of particles :

-Leptons which are particles of matter. like you can touch them. I mean if you were really, like really small.

-Bosons which are particles of forces. They carry forces. Okay, now you're like...wait, what are you talking about 0.0 So imagine you're on a boat. One of your friend is on another boat. (I'm talking about small boat, not yatch and stuff). You throw a ball to your friend. Let's also say you know how to throw and your friend knows how to catch a ball. So, you throw this ball, and your friend catches it. What is likely to happend is that your friend's boat may move away a little bit. You see, your ball was carrying some energy, some force and carried it to your friend's boat. Bosons kinda work the same.

So here is the standard model of particle physics.

                                                   Standard model of particle physics

There are 6 quarks, 6 leptons and 4+1 bosons, each boson correspond to a fundamental force.
g: Strong force (the one that keeps quarks together)
W and Z: Weak force
γ (also called photon) : electromagnetic force

So now you can try to put them together the same way you used to do with your lego when you were a kid...(Well there are some rules...but same with lego right...)

                                          Haha...We're so happy swimming in legos!!!! x_x

After a century of intensive reseach, gigantic installation like the CERN, the puzzle is finally completed!

Sophie in cognito

Welcome!

Lovers of knowledge, Explorator of the world or simply  a human being facing the mystery of life,

here is a place where we should share our enthusiasm about learning.

We want to create a place where philosophy and physics would be at the center of the reflexion.

For too long those disciplines have been ignoring each other. Philosophers are having a hard time communicating with physicists and physicists, lost in their bubbles, sometimes forget the world that surrounds them. Thinking about the origin of those disciplines in Ancient Greece makes it obvious that philosophers and physicists are soul brothers. And that's what we want to restore.

In this blog, we are going to talk about the mysteries of the universe, the theory of the Big Bang, the fascination for particle physics as well as the notion of Existentialism, Humanism...  We are also interested in the intrinsic relation between physics and philosophy through topics such as quantum physics, the quest for the origin...

If there are some particular topics that you think should be discussed please let us know.

Thank you.

Sophie incognito

The philosopher to the physicist (or vice-versa)