søndag 20. oktober 2019

The Big Bang theory

I have for many years wanted to visit one of the largest scientific instruments in the world. The Large Hadron Collider on the border between Switzerland and France. A giant accelerator that pushes protons up to nearly the speed of light. In fact, their speed is only 3 m/s or around 10 km/h below the speed of light.
The story goes that the famous Albert Einstein sat in a patent office in Austria in his youth. Probably bored stiff. At least he spent some of his time thinking and dreaming up what would happen if you moved at close to the speed of light. And weird things happen. At least from our more day to day perspective. Time itself changes (in a more fundamental way than the way it appears to drag out forever when you wait for your washing machine door to open). Dimensions get distorted. Suddenly, what you and I observe may be radically different. And in this realm of weirdness, the building blocks of all matter are whizzing around. More than 9 000 times around the semi-circle that makes up the collider, per second.
And now and then, a few millions of those protons are diverted into another tube. Facing protons going at the same speed in the opposite direction. And at this unimaginable speed, they smash together. Some head on. Others gracing eachother. From the energy released in each of these collisions, new particles are created. Shooting out from the mini-big-bang. Some of these live a "long" time. Others pop in and out of existence in such a short time that it is simply unfathomable. But their existence is recorded by giant instruments. Detectors the size of halls. Thousands of tons of metal, magnets, wires and electronics. Making sure that even the shortest living particles are registered as they play cosmic peekaboo with the scientist.
The closest city to CERN, the organization behind the collider, is Geneva. A city known for more than big bangs. But although it has its interesting spots on its own, my focus for this trip was the area in a small township west of Geneva.
The day I arrived, I walked down to the giant water fountain. Feeling all touristy. Set in the water and spraying a geysir of water 140 meters into the air. With an exit speed of around 200 km/h. I tried coming as close to it as possible, but the wind caused spray to cover my camera, and my self. So I stayed at a safe distance. It was a magnificent sight. I had gotten some information from a colleague of mine who used to work at CERN, for some sights in Geneva, but I had clean forgotten all of them. So I just spent the day walking around. Looking at people and houses. And eating ice cream. The day was sunny. It looked like it was going to be a warm weekend.






Anyways. I had a ticket for 12 o'clock on Saturday. But anticipation got the better of me, so I got on the CERN-tram in time to be there at 11. Just to check things out. The tram was packed to the rafters. As we landed at the stop at CERN Meyrin, it was obvious I wasn't the only one interested in the smashing of protons. In the massive amounts of people, I found a few with vests indicating they should know something. And they pointed me to a tent where they would scan my ticket. Much to my surprise, they didn't care about the time, and I got my wristband and could enter. My first stop was, of course, the Atlas instrument. It took waiting in line for almost an hour and a half in the warm sun before I was allowed, not into the abyss, but rather to get some information while waiting for my group to enter. Our guide walked us through how the detector worked, and some of its history. And how the collider worked. It is truly amazing that this smasher can accelerate particles to near light speed. And just the shear scale of this thing is impressive. Our guide pointed out the mountains in the background. "We are standing more or less above the accelerator here, and it stretches all the way over to those mountains". Just the thought that despite the size, the particles shoot through the circle in just over 100 microseconds, is mind-boggling.
Finally we were led down into the abyss in an elevator. We were warned not to enter if we had any claustrophobia. Luckily, I don't have that problem. 100 meters down we went. And the first thing you can hear when opening the door, are fans. Lots of them.
It is impossible to describe, neither by words nor images, what it is like to stand in front of this massive machine. With wires, magnets and supports. Hundreds and thousands of tons of it. Massive machines are needed both to see the super far away, and the super small. And I love standing in front of both of them. I have included some of the images I took, below.

Some info while waiting in line.

Painting of the Atlas instrument on the building above it.

Development history

No radiation now, luckily...

The detector, cut-through drawing

Seriously strong magnets present....

Need a lot of computers and network speed to process data

Going into the detector cavern

The muon detectors. As we walked through the cavern, we walked past these tubes. Looked like ordinary aluminium tubes. Until our guide told us they wer actually detecting muons. Suddenly, tubing became interesting...

Inconspicuous....

...but a real detector nonetheless

Do not touch!



Inside the Atlas, we see the huge hole they use for adding and removing stuff

The core of the Atlas.


A man for size comparison...
Phew! It is impressive! I wished I could climb the thing and take a closer peek. But with a gazillion people waiting in line, we had to move on. I was lagging behind the group. Taking as many pictures as possible. And just soaking in the view. And this video might give an impression.



After ascending to the surface again, I entered a tent that looked interesting. Lots of stuff to do for children of all ages. I looked at some board with a list if particles, when one of the guides came up to me and asked if she could tell me about the particles. I said yes. I assumed she was just a tour-guide with basic facts of the matter (pardon the pun..). But as we talked, I was impressed with her level of knowledge. She revealed that she had done some work of the Higgs boson for her PhD here at CERN. Euuukey! Suddenly I felt like the stupid one. We spent an hour going through how the Higgs was found, and her minor, but important piece of work in doing so. I learned more about particle physics in that hour than I did at the university for a whole semester. She let me pick her brain until mine was melting. I eventually told her I needed a break to prevent my head from exploding. "Oh, I'm so sorry!" she said with an apologetic look on her face. I waived her off. "No! No! No! I absolutely love this! This has been one of my most interesting convos in years! I guess I have given you a headache with all my stupid questions!" She laughed.
I will do my best to explain, in as layman terms as possible, what we discussed. If you feel like this is stuff that will make your brain melt, don't worry. It did the same to my brain... And if you don't feel like learning particle physics, skip this and just look at the images, and say "WOW" to yourself.
When we think of particles, we tend to think of them as solid objects, like billiard balls. And I have too, until my guide into the realm of the super small unwrapped the fallacy of such thinking. No particle is a ball of anything. It is a "probability distribution". The centre of the particle is the place where you are most likely to find an "incarnation" of the particle. We tend to think of the particle as something solid. But as she explained, she talks about mass and energy as equal terms. And that makes sense in light of the famous Einstein equation E = mc2. So all the masses of the particles she showed me, were expressed in eV, which is a measurement of energy. 1 eV = 1.6x10-19 joule. Or to make it more obvious to those not nerdy inclined, you need approximately 25 000 000 000 000 000 000 000 eV to make one kcal... The mass of the Higgs boson, for instance, has been measured to be 125 GeV, or 2x10-8 joules. Or approximately 130 times more mass than a proton.
So to get back to smashing. When the particles collide in the smasher, it is not like billiard balls, bumping into each-other. They are "clouds" of probability distributions. Like the following illustration (not an actual particle probability distribution).

https://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Gaussian_2d.svg/300px-Gaussian_2d.svg.png 

When two of these collide, they can collide peak on peak, or just barely grace each-other edge on edge. She explained that when they collided edge on edge, or edge on peak, all they got was "garbage". Less massive particles that had nothing to do with the Higgs. Therefore, it was imperative that they managed to focus the beam of particles as much as possible so that as many of the collisions happened as close to peak-on-peak as possible. Now this may seem like an easy task, but you have to remember, these particles are S-M-A-L-L. So even if you send millions of them on a collision course, and squeeze them tight, they will still have oceans of space between them. Its like when two galaxies collide. Stars crashing into eachother is actually a rare event.
Much to my surprise, the Higgs was never detected directly. It is so short lived that it more or less immediately decays into other particles. Which means that they have never actually seen the Higgs. Which I found very interesting. Its like if someone blows up a car with dynamite. And you arrive after it has happened. No matter where you look, you will only find twisted metal and peices of glass. But if you pick up enough pieces, you might be able to determine that it was a car to begin with. And if you are lucky, even the make and model. Something like this is happening when detecting the Higgs. Where there used to be a Higgs boson, there are now just "bits and pieces" flying through the detector. But if you wade through the insane amount of data collected, you are able to trace the different particles back to their origin, and figure out which comes from which decay. Or if they are just a result of a gracing collision. In other words garbage. This is, of course, by no means a walk in the park. But it is possible. And her work was part of this cosmic jigsaw puzzle. She was tasked with finding a certain type of decay. Where the Higgs decayed into a pair consisting of a W-particle and an "off-shelf" W... And this was the weird stuff. Or, dare I say, ANOTHER piece of weird stuff... The particles have their given rest mass. But they may still exist with other masses. And these weird half-breeds can exist as products of a decay of the Higgs. She explained me why they were called "off-shelf". It is like nature decides to produce a W-particle. It pulls out the mold and starts filling it with energy. But it doesn't have enough energy to fill the mold. Now, it is still a W, with all quantum properties of a W, since the mold is for a W. But it never really reaches "maturity". Nature then just throws it into the cosmic void where it goes "paphooey!" and in a fireworks display turns into other particles. Now what are these quantum properties? At this point, she had reached the limit of her explaing powers. Hah! Finally! It felt good to finally come up with a question she couldn't answer. But I was glad too. My brain was starting to melt at this point. But in her defence, when I took a class in quantum physics at uni, I felt like a moron most of the time. And in the words of Richard Feynman : "Nobody really understands quantum physics!" So yeah. There's that.

A rare image of the Higgs boson. From CERN

Soooo. Now we know (a little)  of how the Higgs is detected. But how is it formed? In a numerous ways actually. But I choose to pick up one of my favorite ways of those she showed me. Much because it also involves the closest thing you can get to magic in quantum physics. Although most of it sounds like magic anyway... But I am talking about energy lending.
Now, we are all familiar with the consept of "what goes in, must come out". The reason I am overweight, is because I stuff more calories into my body that what I burn. We tend to find other explanations for it, but that is the most reliable one. In the quantum world, however, the Universe can lend you energy, often massive amounts of it, to create particles that normally should not come out of an equation. So it reminds me of a cartoon I once saw in a science magazine. A student is doing some math for his exam, and have written some math on the left and on the right of the blackboard. And between the two, the words "..then a miracle occurs.." are written. The professor looks at the calculations and asks the student "can you be a bit more specific in step two?"
Let's look at quark-quark interaction. "What are quarks?" I hear you screaming. Since the beginning of time, people have pondered what the basic building blocks of the universe are. To a certain president, his ego. To a mason, bricks. But to a particle physicist, they are quarks. Protons and neutrons, the things that make up atoms, are made up of three quarks. So it feels like one can paraphrase the old world view : Particles all the way down...
Sooo. Get ready to dive into the realm of quantum magic. Two quarks interact, and nature goes "Awwwww, that's cute!", and decides to give them a baby. A Higgs boson. Problem is, the Higgs is 150 times more massive than the two quarks combined. Soooo. How does this cosmic interaction produce such a massive baby? Quantum weirdness. In a cosmic version of a bank, nature creates energy out of nothing and puts it into the mix. And Poof! In a hall of smoke and mirrors, the Higgs is born to loving quark parents. But, as I have already pointed out, the Higgs is a very short lived baby. So it quickly goes "Kapoooof!" and to the shock of its parents, and probably some of the audience of this terrible explanation, it turns into several other particles. Which flies off into certain oblivion, were it not for their origin. Their short existence is registered as a streak across a processed image on a computer screen. And their fame is only secured because they happen to be decendants of the more famous Higgs. Otherwise, they would have been erased from history as mere "garbage".
So where does the energy come from? Well....errrr...nowhere. It just appears to create a particle. And then disappears again into the cosmic void.
At this point, if you feel like your head is about to explode, no worries. So was mine. I told my excellent guide I would be back when my brain had cooled.
So I walked out of the tent, and found a food-wagon where they sold Pad Thai. Got me a bowl and something to drink. Sat down on some stairs and ate. Trying to process everything I had learned. As the spicy meal was tingling on my tongue, the thoughts were tingling in my brain. And like the Higgs, questions popped into existence. I wrote them down on my phone before they decayed into randomness. Teflon brain needs external storage...
After the meal, I decided to rest my brain and went to see the expo in the dome at the entrance.


 A short film was projected against several of the walls inside the dome. Giving a short presentation of the universe of particles. All set in a soothing blue light.


They also had several domes which contained pieces of the history of CERN, and particle physics and particle accellerators. Very interesting.

First ever accellerator. Real size.

The beam tubes in the accellerator at CERN





Now I was ready to pick me some brains again. I walked back into the tent and found a familiar face. "Ah! You have more questions?" she said and smiled. "Yup!" She saw my phone. "Oh! You have questions on your phone?" She looked almost scared. "Yeah. Teflon brain needs it to remember them"
Naturally, I thought I had my Nobel price figured out in my first question.
"You know the so-called 'dark matter'?"
"Of course!"
"Of course you do." (Kept forgetting she was not merely a guide...)
"What if this is just areas in space with a higher concentration of Higgs bosons, creating stronger fields there?"
"No"
"No?"
"No"
"Why not?" (seeing my Nobel price flying off into the distance)
"When the first Higgs bosons came into existence, they created the Higgs field. And this field permeated the universe. And it is stretched with the universe. Which means that it is everywhere. And has always been. And it is not dependent on the number of bosons. Just that they exist."
*Brain into overdrive*
"Soooo...errr....If the field is stretched, can it rip?"
She thought for a second.
"I guess it might"
"And we and everything would cease to exist in less than a blink of an eye?"
"Yes!"
Ooooo. Nice setup for a Hollywood movie!
Hero with loads of muscles: "The Higgs field is about to rip! Get everybody outta here! We need to get them to another universe! Bring out the cross-universe transporter!"
Somebody with more brains than muscles : "Excellent plan with only two minor flaws: 1) We don't have enough energy to power the cross-universe transporter, and 2) we don't actually have a cross-universe transporter!"
Hero with loads of muscles: "Wait...what?? We don't have a...aaaa forget it. Go about ur busin..... Rrrrrrriiiiiiiip!"
Everything disappears. The hero doesn't even get to slo-mo-shout "Nnnnnooooooooo!" All that is left is energy, bad ideas and baffled audiences feeling the Higgs field wasn't the only thing being ripped off. The end.
The answers to the rest of my questions are in the descriptions of the quantum physics above.
At this point I was sure I had given her a head-ache. I thanked her from the bottom of my heart for her patience and great answers.
I really hadn't checked what else was at the site, so I just walked aimlessly around. Bought some souvenirs and took the CERN tram back to the centre before they closed the site off to the public. Bought some crap at a store and went back to the apartment. I only had a ticket for this day, but wanted to see more. I had a few hours in the morning before I had to head to the airport. So while laying in bed, watching bad movies, I checked the website and found they still had tickets for the day after. But only for a 4 o'clock arrival. Given the fact they didn't check my time-slot when I arrived, I was hoping they wouldn't on Sunday either.
On Sunday morning, I got up, had a quick shower, and left the apartment. On to the CERN tram. There were a lot less people this day. And maybe time of day. When we arrived at CERN, I found a guy at the platform who was handing out wristbands. I walked over to him.
"Do I get one?" i asked expecting him to ask me for a ticket
"Sure" he said and tore off one for me and put it around my wrist. I was in!

A bit worn now. But still.


Like a boy in a candystore, I was off. This time, I wanted to see a lot of smaller stuff. Like the electronics shop, the power station and the primary accellerator. First, the electronics shop. When I arrived, there were nobody there. So I stood in line. A guy came up to me "English?" I nodded. "Come with me!" Hmm. Not many people wanted to see this???
He brought me a woman through the process from the first designs (which could come in the form of a literal napkin), to the finished product. Very interesting! And as a bonus, we left with some souvenirs! A small gadget produced at the site. Although not very advanced, I love that they are produced here. Ok, I'm a nerd! Get over it!

The biggest electronics they make. A detector.

Rows and rows of parts


Lotsa prints ready for...errr...printing
The printing of solder paste on the...errrr...prints...



Macgine for reflow of solder


After this, I got in line to see the first synchrotron at CERN. Its a form of simple accellerator that makes particles shoot around and arund while they pick up speed. Until they smash into something. Simply put. Much to my surprise, it was actually in use up until 1990! It was now relegated to a makeshift museum. With "interesting" lighting and a short information video, which was actually supercool! They had managed to project images onto the synchrotron itself that made it look like the whole shebang was transparent. Cooooool! We got to take a few selfies before we had to leave for the next group to enter.



I had read on the CERN Open Days app that they had a tesla-coil show at the power station. Of course I wanted to see that! Ok, No images here, but I recorded a video. They were playing music with lightning and demonstrating how the faraday cage worked. I love this!



My last stop were at the primary accellerator. Where the protons start they perilious journey towards a big bang. I got to see the previous version and the new. Both of them accellerate protons from more or less rest speed, to almost light speed before they are sent into other, more powerful accelerators to give them even higher speed. Until they are sent into the LHC, which brings them up to 99.999999% of the speed of light.
But the beginning is humble. A bottle of hydrogen. A small puff of hydrogen is led into an apparatus that turn it into plasma. At this stage, electrons are separated from the protons in the atom. And the protons are fed into the accellerator.

The humble beginning. A bottle of hydrogen.

We were told that the "pulse" of the system was 1.2 seconds. Every 1.2 seonds, a new batch of protons where accellerated down the LINAC and shot into the system. Which basically meant that every 1.2 seconds, it should theoretically be possible to create a big bang in one of the detectors in the LHC. Every 1.2 seconds, 24/7. Almost every heartbeat of a human, there is an explosion in the LHC. Producing new particles.

Some..err...advanced stuff accelerating the protons.

Whisking the protons to near lightspeed.

As we exited, I saw these two waste...err...something. They have obviously found good use of the black holes they are producing. Just lift the lid and drop whatever into it, and the garbage will be gone. Nice!...


A perfect ending to my visit. The pulse of the accellerator may have been one per 1.2 seconds. But as I realized I had little time left before my flight, my pulse was shooting. I zoomed back to the tram and got to the airport. Only to find I had remembered the departure time incorrectly. So I could have spent another hour or two at CERN... Oh, well. Maybe next time.

Ragnar
Aka "Low speed collection of quarks and electrons"

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