First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)

[Iroscato]

Well, for starters are you able to give this layman a brief explanation of the stong and weak forces? What they? What do? And why?

First of all you have to know that all forces can be seen as the exchange of virtual particles. the electrostatic and magnetic forces for example are communicated by the exchange of virtual photons, the same guys that make up light if you give them some more energy.
What is a virtual particle? Well, that's kind of a technical issue. Think of it as a particle for which there really isn't enough energy present to make one, but which for a short amount of time can defy this hindrance thanks to some sort of uncertainty principle, which allows particles to appear for a short time.
Now, there are many more types of particles in nature which can also cause forces when they are exchanged, but most of them have a much much shorter range than electromagnetism - for different reasons. There are the W and Z bosons, and when they are exchanged one talks about the "weak force". It is actually not weak, but of very short range, because the W and Z bosons are so heavy. This makes it more unlikely that they propagate spontaneously as virtual particles over longer distances, and hence the range is short. The most obvious effect of the weak force can be observed when W bosons are exchanged, because they change the type of particle. They make electrons out of neutrinos and vice versa, and protons out of neutrons, as an example. Therefore, the exchange of a virtual W boson can turn one type of atomic nucleus into another lighter one,  and produce an electron and a neutrino out of the spare energy. That's beta decay.

There are also the Gluons, and they have a somewhat longer range because they are actually massless like the photons, but since they bind to each other, they basically keep themselves from travelling long distances. These guys lead to a very strong binding force between particles which can interact with them - themselves and the Quarks, and the exchange of Gluons can therefore bind Quarks together to form Protons and Neutrons. This is often called the strong force.

But nit just elemdntary particles can cause forces. Pions which are actually pairs of a quark and an anti quark, themselves can be exchanged between protons and neutrons. This isthe force that holds the nuclei of atoms together - even overpowering theelectric repulsion between between protons. This effect is also calledstrong force.

Any clearer?

Wow.
...
Surprisingly, yes, that actually helps a fair bit. Thanks for taking the time out to explain it to me

[Alex K]

Well, I don't know whether I was really taking time out. I was sitting between some trees in a shady garden, birds chirping, a piece of cake and a glass of wine in front of me. Writing a treatise on forces was just the right dose of physics to enrich such an idle afternoon...

[Longhorn]

Was it your bday cake? Is it as hot in Germany as it is here (as fuck)?

[LastPoet]

What would you call hot?

[Longhorn]

+35 Celsius

[Iroscato]

Double figures celsius is where my 'hot' starts. I am VERY much a winter man. For starters snuggling doesn't result in immediate, irreversible heatstroke

[Alex K]

Was it your bday cake? Is it as hot in Germany as it is here (as fuck)?

It's hot, too hot to really do anything but sit in the shade and read and sip a cool drink. It was bday leftovers plus two new cakes

[JuliaL]

First of all...

OK, I'm lost already.
But I'll take a shot at demonstrating my ignorance.
Particles trade particles to other particles to make particles or to change particles or to hold particles together against other trades of particles.
But we don't know what a particle is, just how it acts, what it does.
Its sort of particle economics with trades of derivative products which are composite things that don't really exist except for the purpose of trading things to other things on the NYSE to eventually make real things like cash or land ownership.
Sorry, I can't do the math so I have to talk in metaphors.

So in these exchanges, do the 'real' particles know about each other in order to trade 'unreal' particles?
Do they find out about each other by 'fields' (other things whose only evidence of existence is what they do to other things.)
If all these interactions are by exchange of particles, how do the 'real' particles pick which virtual particles to exchange?
And why do you need so many of them to get any rock crushing done?

---

you have to know that all forces can be seen as the exchange of virtual particles. the electrostatic and magnetic forces for example are communicated by the exchange of virtual photons, the same guys that make up light if you give them some more energy.
What is a virtual particle? Well, that's kind of a technical issue. Think of it as a particle for which there really isn't enough energy present to make one, but which for a short amount of time can defy this hindrance thanks to some sort of uncertainty principle, which allows particles to appear for a short time.
Now, there are many more types of particles in nature which can also cause forces when they are exchanged, but most of them have a much much shorter range than electromagnetism - for different reasons. There are the W and Z bosons, and when they are exchanged one talks about the "weak force". It is actually not weak, but of very short range, because the W and Z bosons are so heavy. This makes it more unlikely that they propagate spontaneously as virtual particles over longer distances, and hence the range is short. The most obvious effect of the weak force can be observed when W bosons are exchanged, because they change the type of particle. They make electrons out of neutrinos and vice versa, and protons out of neutrons, as an example. Therefore, the exchange of a virtual W boson can turn one type of atomic nucleus into another lighter one,  and produce an electron and a neutrino out of the spare energy. That's beta decay.

There are also the Gluons, and they have a somewhat longer range because they are actually massless like the photons, but since they bind to each other, they basically keep themselves from travelling long distances. These guys lead to a very strong binding force between particles which can interact with them - themselves and the Quarks, and the exchange of Gluons can therefore bind Quarks together to form Protons and Neutrons. This is often called the strong force.

But nit just elemdntary particles can cause forces. Pions which are actually pairs of a quark and an anti quark, themselves can be exchanged between protons and neutrons. This isthe force that holds the nuclei of atoms together - even overpowering theelectric  repulsion between between protons. This effect is also calledstrong force.

Any clearer?

---

[Pyrrho]

Well, I don't know whether I was really taking time out. I was sitting between some trees in a shady garden, birds chirping, a piece of cake and a glass of wine in front of me. Writing a treatise on forces was just the right dose of physics to enrich such an idle afternoon...

That sounds lovely.  The only way it could be much better would be to have an entire bottle of wine, and someone to share it with and...

From The Rubáiyát of Omar Khayyám, as translated by Edward FitzGerald, fifth edition:

XII.


 A Book of Verses underneath the Bough,
 A Jug of Wine, a Loaf of Bread--and Thou
   Beside me singing in the Wilderness--
 Oh, Wilderness were Paradise enow!

https://en.wikisource.org/wiki/The_Rubai...h_edition)

[Alex K]

Brilliant questions, will try to address later. But yes, I talk of theory objects as if they are objects in nature. I don't know what is *really* going on, and that's possibly not a phtsics question