Does Higgs boson discovery mean String Theory is dead?

Originally posted by TrueBrit
Someone said that they do not believe that the Higgs and its attendant feild actually exist. Others have said in this thread, that no one understands string theory.

The reality is that there has been a massive drive to discover the veracity of the Higgs boson, which has attained results which, according to those who actually worked at the project, and have reveiwed the raw data from the experiment, show the Higgs to be the real deal.

Where string theory is concerned, there has never been an experiment performed which showed any of its assumptions to be unassailable. Of the two then, I am more inclined to favour the Higgs because there is actual evidence for its existence.

One of the things that I love about science in general, but physics in particular, is that a premise which is posited, is only validated by evidence. String theory, interesting a concept as it may be, and educational in some areas as it most certainly is, has not been validated, nor indeed has any widely understood effort been made to do so, probably because the very essence of these strings is so intangible and mysterious, that the mind cannot begin to see how one might go about isolating and examining such a thing.

Sometimes theoretical physics, and those who are involved with it, become so caught up by an elegant idea, or an entertaining and exciting chain of thought. Like old time gold miners, they can get locked onto what looks like a seam leading to a motherlode, only to come up holding iron pyrite. Now, given the complexity of the subject that they deal with, one can understand them having the occassional flight of fancy, but the real sticking point for any idea is when it comes to the point that engineering skills, materials, and manpower come together, to allow a person to TEST these theories. When that happens, a theory can have itself, or its elements properly examined.

If string theory has any value what so ever, then mankind is currently unable, for one reason or another, to test for the presence of these strings, so to know for certain that string theory is dead we may have to wait a while. In the mean time, we have the Higgs boson, and all the possibilities that working with a particle which imparts mass on others, presents for the human race. I think thats more than enough for one species to be getting on with for the moment! Dont you?

While the possibilities inherent in the Higgs discovery are explored, there will be others seeking to delve into other fields. So it's basically a given that whatever our thoughts are on the subject, research and theoretical conjecture will continue.

Having said that, I suppose we could rest on our laurels and just believe we're done with our search for the makeup of the universe, but that's hardly been the human way, and I don't think it's what we should be doing.

I happen to be one for the "keep going" (cautiously) camp. Consider that theoretical work on matter/energy interaction is what gave rise to nuclear power. Also bombs. But thankfully the bombs have been few and the power plentiful. Yes, Fukushima an Chernobyl are examples of the power aspect going wrong, but there are many more examples of where we get plentiful power without much pollution otherwise. Who knows what further exploration can produce?

Every discovery opens the box for both good and bad applications, but given the problems humanity is facing I don't think we're at the Utopia we need to be in before we call it quits. We could also try to stuff that genii back in the bottle but I don't even know if it's possible, and considering all that it's produced (higher population, power demands, etc.), reverting back would take a global, concerted, and potentially disastrous effort.

As an experimental particle physicist I can tell you some of what i know of this field though I wont pretend to really deeply understand heavy theoretical physics. Anyone who has studied some QED, QCD and QFT will tell you that it just hurts your brain, and after you are done you want to take a spoon and scoop out the parts that remember it and throw them away.

The issue with alot of these theories is how people and the media present them (as has already been touched upon) The standard model is not complete, so we have a discovery (is it evidence or discovery? what was the sigma?) the last time i checked the predictions of cross sections around the probable higgs center of mass energy was not correct as per the standard model, thus a few things need to be changed/modified.

Furthermore the area of neutrino physics is kind of an open hole in the standard model, there are g-2 experiments that are showing that while we have the electron down and understood, what the theory predicts about the muon is not correct.

Anyway there are lots of gaps that are being slowly filled in.

Anyone who says scientists are not open minded obviously was not exposed to many scientists or was unlucky in their exposure. Yes we have our 'thinking inside the box' but it is outside the box where we all want to get, but the issue with theories such as string theory is that many of them have thousands of parameters, and the more parameters you have, you can tune to represent anything, because something is mathematically nice or eligant doesn't necessarily mean it is correct. It is like the maximal mixing in the neutrino sector, mathematically it has a very nice diagonal form that is roughly 0, 35.5, 45 across the diagonals. There is absolutely NO theoretical reason why it has to be like this, but it makes for some nice maths... Just so happens that though the reality appears to be almost tribimaximial it isnt exactly and that 0 is not 0, it is smalll but non-zero, which gives rise to possible CP violation in the neutrino sector and a window on lepto-genesis in the early universe.

The Higgs itself came around in a strange way too, it was added as a fix to the standard model because of the presence of mathematical divergences to infinity for a number of cross section loop calculations. It was added as a way of suppressing these mathematically ugly parts (and for other reasons too) At the time it was not accepted because at the time it was an expensive fix to a problem. That is the only reason why theory is not instantly adopted. Science doesn't like to just invent things that solve problems in imperfect theories. It is abit like continuously bolting on bits of metal on a ship to keep it floating, then to keep it balanced, then to say make it look nice.

Back to the neutrino this happened in that sector too, It was first postulated as a solution to beta decay. At the time scientists were honestly thinking of abandoning conservation of energy and momentum because beta decay didnt make any sense. Pauli came along and said... what if there is a light/massless particle that takes away some of the energy and momentum, and it is so weakly interacting that we cant observe it.

Mathematically it is wonderful, it solves the problem, but the reality is you just invented a particle that you cannot detect? (sure about 60 years after, it was detected but the point remains)

Many issues with string theory is that the energy oscillations are folded in on themselves within a plank length (oh and depending on the favourite theory, within 11 dimensions) , which means you cannot directly probe that space, and the observable effects that are different to what we have in the standard model are several (hundred? thousand?) orders of magnitude higher in energy than what we can easily achieve here on Earth currently. So while string theory might be great and be a fix for all ailments it is somewhat not given the same respect and research because currently it exists only on paper and has not been tested outside the realms of the standard model.

Furthermore, a little titbit. Ultra high energy interactions are occurring all the time on the atmosphere, the prediction that micro blackholes be produced and would rapidly destroy the Earth, came from a string theory paper. So this doesn't appear to happen? So sure we cannot say "String theory is wrong" but at least that one pet theory from that paper is wrong.

There is a saying "String theorists are to physicists, what physicists are to normal people" we look at them and think... wow they are crazy haha

reply to post by transmundane


No one is suggesting that we rest on our laurels. Personally speaking, I would deny that we have any to rest on, because we still arent colonising space, or anywhere near to it, despite the rampant clamour for seats on a few of the private space flights and moon walks that are being planned.

However, what I am saying, is that specifically regarding the string theory idea, there are more productive lines of enquiry right now. String theory is stuck in a difficult phase. It revolves around completely intangible things, which as of yet we have no way to run experiments on. Learning HOW to experiment cannot happen until scientists learn precisely WHAT to experiment on. Right now, the people who are thinking about strings have no way to confirm thier existence in the only important way, i.e. by proving thier physical reality.

Originally posted by Moduli


There's no "mechanism" it's just the usual relationship between mass and energy (the Higgs mechanism is actually doing the same kind of thing, too, just in a sort-of different way).

So why was the higgs needed at all? why can electrons and quarks not have their own mass related between energy levels and other particles?

A similar example is that quantum field theory is the most general theory of quantum mechanics without gravity you can write down, and the Standard Model, ordinary quantum mechanics, and special relativity are specializations of that general framework.

Do you have any personal thoughts on gravity? why there are "problems" if any for our view of it at the quantum level?

Originally posted by ImaFungi
So why was the higgs needed at all? why can electrons and quarks not have their own mass related between energy levels and other particles?

Well, without it, e.g., electrons would be massless and wouldn't form bound states with nuclei. Also, it's not that it's "needed," it's a mathematical consequence of the structure of the theory; similar things show up in other areas of physics that use the same math.

Do you have any personal thoughts on gravity? why there are "problems" if any for our view of it at the quantum level?

Well, none of the "problems" you hear about it from the popular media, or even from some of the better pop-sci books, are really what the issue is.

It's not difficult to combine gravity with quantum field theory, it was done as soon as quantum field theory was understood well enough to do interesting things (and even before that, it motivated the development of a lot of the theory). It was already known exactly at low enough energies in the 1960s.

The difficulty is that at high energies, quantum field theory plus gravity is not enough information to constrain the theory, it becomes unpredictive (technically, an infinite number of new constants show up, whose values are not predicted, and who show up in a way that you have to know all of them to make any predictions). This is a signal that some piece of information is missing, and what you're looking at isn't the full theory.

One can ask how to fix that problem (and people did!) and this is one of the ways that one is lead to come up with string theory.

Originally posted by Moduli

Well, without it, e.g., electrons would be massless and wouldn't form bound states with nuclei. Also, it's not that it's "needed," it's a mathematical consequence of the structure of the theory; similar things show up in other areas of physics that use the same math.

Why would electrons be massless? Why arent photons considered free electrons ( is it because electrons show different behaviors when out of an atom then EM radiation? could it be EM radiation is a form of an electron leaving the atom with high energy involved?) ..... could electrons really not have mass while traveling through a vacuum.. and the only reason they form bounds because of their charge? What is a quark made of and how did it form?

The difficulty is that at high energies, quantum field theory plus gravity is not enough information to constrain the theory, it becomes unpredictive (technically, an infinite number of new constants show up, whose values are not predicted, and who show up in a way that you have to know all of them to make any predictions). This is a signal that some piece of information is missing, and what you're looking at isn't the full theory.

One can ask how to fix that problem (and people did!) and this is one of the ways that one is lead to come up with string theory.

When you say at high energies infinite number of new constants show up... are you referring to particle collisions and the resulting debris? Is this much much different then doing a cannonball into the pool and then recording every water droplet that left the pool,, and trying to figure out how and why each droplet left where it did, traveled the height and distant it did etc. etc.? higher energy levels would equal fatter kid doing the cannonball?

my personal thought on quantum gravity...you can tell me how wrong this is.... is that the quantom nature acting exactly the way it does to form more macro structures and more macro stable structures... is the activity which allows macro gravity to exist at all.... that is to say gravity is the result of quantom mechanical particles and waves.. grouping together to form atoms, grouped together to form a planet.... when you take the tiniest part of the macroness and try to put it up against the largest result o the macroness (gravity) its very incompatible..
also my confusion continues,, when thinking that the main theory in physics of what gravity is, is the curvature of space-time... is this the same excuse physicists try to use on the quantum level? quantum particles curve space-time? and then is it thought that the experiment cannot be fully known,, because the space time that exists near and on earth is different then solar space time, galactic space time, and universal space time?
so if quantum particles did curve space time in labs... it would be curving the space time the planet has and does already curve... so it might be difficult to tell ... anything about the quantum particles gravity..

Originally posted by ImaFungi
So why was the higgs needed at all? why can electrons and quarks not have their own mass related between energy levels and other particles?

Well sorry I guess my post was too long, either that or here on ATS as soon as anyone says they have practical experience in a field of interest everyone just skips over it.

The Higgs was required as there is a problem of infinities in QFT, where calculating interactions would essentially give you infinity. This is a plague for a theory because 99.99999% of the time, the infinity is not physical. This was manoeuvred around with the introduction of virtual particles or gauge bosons that 'perform' the interactions, these have in the theory, properties that essentially cancel out these problematic infinities.

Electromagnetic as the Gamma
Weak has the gamma, W+/-, Z
Strong has the gluon,

All well and good, except there exists no mechanism which gives the particles mass, nor any hard standpoint that gives any predictions of exactly what mass each particle should take. This is were the higgs comes in.

This is why when we searched for the Higgs no one could say... yes the energy is exactly x... we essensially said, we need to build the most powerful collider possible, and ontop of that do it with Protons rather than e+/e- because that gives us the ability to push the energy further due to the biding of the quarks.

Originally posted by ImaFungi
When you say at high energies infinite number of new constants show up... are you referring to particle collisions and the resulting debris? Is this much much different then doing a cannonball into the pool and then recording every water droplet that left the pool,, and trying to figure out how and why each droplet left where it did, traveled the height and distant it did etc. etc.? higher energy levels would equal fatter kid doing the cannonball?

This is absolutely not the case, the issue is that in interactions at ultra high energy it isnt just that things break apart, things are actually created from vacuum (from the boson exchange). You cannot simply break apart the quarks, when you hit a quark it doesnt just give you a billiard ball scatter, it is different because the quark is a bound entity and has non integer charge.

At ultra high energies you create jets, these are high energy cascades of hadrons, the process is more empirically understood than theoretically calculated, in a way it is a pure conversion of collision energy to mass.

Originally posted by ErosA433

Originally posted by ImaFungi
So why was the higgs needed at all? why can electrons and quarks not have their own mass related between energy levels and other particles?

Well sorry I guess my post was too long, either that or here on ATS as soon as anyone says they have practical experience in a field of interest everyone just skips over it.

The Higgs was required as there is a problem of infinities in QFT, where calculating interactions would essentially give you infinity. This is a plague for a theory because 99.99999% of the time, the infinity is not physical. This was manoeuvred around with the introduction of virtual particles or gauge bosons that 'perform' the interactions, these have in the theory, properties that essentially cancel out these problematic infinities.

Electromagnetic as the Gamma
Weak has the gamma, W+/-, Z
Strong has the gluon,

All well and good, except there exists no mechanism which gives the particles mass, nor any hard standpoint that gives any predictions of exactly what mass each particle should take. This is were the higgs comes in.

This is why when we searched for the Higgs no one could say... yes the energy is exactly x... we essensially said, we need to build the most powerful collider possible, and ontop of that do it with Protons rather than e+/e- because that gives us the ability to push the energy further due to the biding of the quarks.

so virtual particles and gauge bosons are only helpful mathematical crutches... in physical reality there is no such thing as gauge bosons?

why does there need to be a mechanism which gives particles mass? why cannot the fact that a particle exists in space-time and can interact with others that exist,, be enough of a proof that these particles.. building up with one another increases mass?

Originally posted by ErosA433

Originally posted by ImaFungi
When you say at high energies infinite number of new constants show up... are you referring to particle collisions and the resulting debris? Is this much much different then doing a cannonball into the pool and then recording every water droplet that left the pool,, and trying to figure out how and why each droplet left where it did, traveled the height and distant it did etc. etc.? higher energy levels would equal fatter kid doing the cannonball?

This is absolutely not the case, the issue is that in interactions at ultra high energy it isnt just that things break apart, things are actually created from vacuum (from the boson exchange). You cannot simply break apart the quarks, when you hit a quark it doesnt just give you a billiard ball scatter, it is different because the quark is a bound entity and has non integer charge.

At ultra high energies you create jets, these are high energy cascades of hadrons, the process is more empirically understood than theoretically calculated, in a way it is a pure conversion of collision energy to mass.

ok so at high energy things like quarks which are fundamental which do not have components in and of themselves but are what they are..... they cannot break right? so it is the momentum of two quarks colliding.. converting that non material energy into "something"? do quarks lose any mass when they collide?

so now im picturing two "indestructible" bullets colliding... they have their rest mass and energy... and also the energy contained in their momentum when they are fired...... when the two bullets collide they do not lose any mass or material... but energy is released/converted..... we are familiar with bullets so we would imagine sparks of some kind? i am not familiar with quark collisions so i should imagine vacuum jets of some kind as you say?

but now im thinking if no mass leaves the bullets they wouldnt even spark... it would just be friction and heat released from their collision... and you are saying with particle collisions... the resultant heat energy released from the collision.... forms into semi stable "particles" of matter them self with the help of the vacuum (?),,, or just in the vacuum?

mmm ok so using the idea of bullets, its like if you saw two bullets collide head on, perfectly, you would then see collimated groups of say 100 bullets emerge extremely close to the interaction point (maybe a spark as you said) going back to back. The two original bullets would probably not exist by this point, and you would also get a few other bullets flying out in different directions.

So high energy interactions with quarks are truly a complete mess. e+/e- colliders are alot cleaner as you annihilate the electrons, rather that bouncing the quarks off of each other.

The best way I can describe it is that if you have a proton, it has 3 quarks, if you hit one of those 3 quarks with one of the 3 quarks in another proton (two protons collide essentially), assume for a moment that one quark has more momentum, the quark with the lower momentum is knocked out of the proton.

Now i think in QCD you cannot have an unbound quark, so as the gluons that bind the quarks get stretched out, eventually a quark is created, the energy required to do this is taken from the energy of the interaction, so the proton looses some energy and another quark is created and the two quarks move away as say... a meson of very high energy.
[edit]
You asked where the energy comes from, it is i believe the binding energy of the proton, as the quarks are held together by the strong force/gluon exchange. So as the quarks separate, some of the momentum is converted into a quark. It is hard to describe, it is like condensing mass out of energy, if you call this energy, a boson then i guess that would be correct. Where does the energy come from? Momentum energy.
[edit]

This kind of process can produce a high array of particles, and this quark that you create doesn't have to be of the same generation as the originals. What can happen in that interaction is enormous.


Needing the higgs to give you mass, well I am with you in a way, I always ask, why? why does the theory need it to allow mass? Well it is just how the theory is, without this boson/field, the model on its own does not contain mass as a predicable variable. You cannot look at the up and down quarks and predict what the masses of the strange and the charm. In fact you cannot take the theory at a fundamental level and predict the mass of any of the particles, and this is a little disconcerting given that the theory predicts what happens during interactions to a high degree of accuracy.

Originally posted by ImaFungi
Why would electrons be massless?

Because they're the kind of particle that the Higgs mechanism gives mass to.

Why arent photons considered free electrons

Because they're completely different particles. Photons don't have any electric change for example. They're described by completely different equations of motion. The unified theory that describes both is called electroweak theory.

When you say at high energies infinite number of new constants show up... are you referring to particle collisions and the resulting debris?

What I mean is, if you wanted to measure some quantity, say, "x", then you would find you would have to calculate something like:
x = a0 (stuff) + a1 (more stuff) + a2 (stuff again) + a3 (more stuff again) + ...

Where a0 is large and contributes the most, and is the "low energy" part, but all of the other a's are the same size, so the an (stuff) parts are all equally large, and so you're required to know them all to make any predictions.

In other words, to fully determine the theory you'd need to do an infinite number of experiments to determine all of the a's.

Is this much much different then doing a cannonball into the pool and then recording every water droplet that left the pool,

Yes, it's completely different.

my personal thought on quantum gravity...

I don't really understand what you're trying to say. But normal "macroscopic" gravity is just microscopic gravity averaged over the small distances. There's a well-defined procedure to do this that's been known for 30 or so years, it's an important part of modern particle physics (called "effective field theories").

Originally posted by ErosA433
The Higgs was required as there is a problem of infinities in QFT, where calculating interactions would essentially give you infinity.

This is a pretty dysfunctional explanation. It's one you sometimes hear from physicists because it's a small part of a much bigger picture, and pointing this out makes it obvious once you understand it, but by itself this is not an explanation of anything.

The Higgs mechanism is mathematically required in the framework of the standard model. It's not something that's added to the the theory, it's something that is derived from the theory. It's true that if you randomly deleted it, things would diverge, but that's because you made the theory mathematically inconsistent.

This was manoeuvred around with the introduction of virtual particles or gauge bosons that 'perform' the interactions, these have in the theory, properties that essentially cancel out these problematic infinities.

Everything about this sentence is wrong. Virtual particles have nothing to do with this, and nothing is "introduced" to the theory. I think you're confusing three or four issues you've had poorly explained to you together.

This is why when we searched for the Higgs no one could say... yes the energy is exactly x...

That's not really true, the Higgs determines masses, so having measured masses tells us what mass the Higgs can be. It wasn't known exactly before measuring it because of experimental errors and technical issues (such as which particular spectrum of Higgs particles is realized by the Higgs mechanism in this particular case).

Originally posted by ImaFungi
so virtual particles and gauge bosons are only helpful mathematical crutches... in physical reality there is no such thing as gauge bosons?

No, that's totally wrong. Gauge bosons are perfectly good particles. The photon, for example, is the gauge boson associated with electromagnetism. Virtual particles are perfectly good things, too, just ones that show up as intermediate states that you don't measure.

why does there need to be a mechanism which gives particles mass?

There doesn't need do be, there just is. It's just how nature works.

Originally posted by ImaFungi it is the momentum of two quarks colliding.. converting that non material energy into "something"? do quarks lose any mass when they collide?

Quarks don't lose any mass when they collide. Collisions produce extra particles because the total amount of energy is conserved, but can be converted from the initial kinetic energy into other particles.

so now im picturing two "indestructible" bullets colliding... they have their rest mass and energy... and also the energy contained in their momentum when they are fired...... when the two bullets collide they do not lose any mass or material... but energy is released/converted..... we are familiar with bullets so we would imagine sparks of some kind? i am not familiar with quark collisions so i should imagine vacuum jets of some kind as you say?

A classical collision is completely different than a quantum mechanical one. So you can't really try to understand one in terms of the other. You're only going to be mislead thinking that way.

Originally posted by ErosA433
Now i think in QCD you cannot have an unbound quark

That's true at low energies, yes, although at high energies you get a quark-gluon plasma which you can think of as made up of free quarks.

You asked where the energy comes from, it is i believe the binding energy of the proton

The energy to create the new particles comes from the initial kinetic energy plus the internal energy of the nucleons. It turns out it's not easy to estimate the details of internal energies of a real-life collider, and that's part of what makes it so difficult to analyze results from them (although it's easy enough to come up with idealized models where you can calculate that kind of thing, of course).

the model on its own does not contain mass as a predicable variable

That doesn't matter because that was never a requirement of the theory. And the Higgs doesn't determine all masses either, e.g., neutrino masses are probably determined by something like the seesaw mechanism. The Standard Model has many independent parameters whose values are only determined by experiment.

Originally posted by ErosA433
There is a saying "String theorists are to physicists, what physicists are to normal people" we look at them and think... wow they are crazy haha

String theorists are to physicists what inmates are to psychiatrists.

The stringed inmates think they understand the world better than the psychiatrists, and they think the psychiatrists almost understand what they're talking about but just don't quite get it.

reply to post by mbkennel


I think it is fairer to say that theoretical physicists, and those who participate in practical experimentation are different in several important ways.

The job of a theoretical physicist is to imagine new ways to describe the universe, and every function that it performs. The task involves little more than standing at a blackboard, or sitting in front of a computer, while comming up with mathematical constructs that could explain a system or function. They run models, they churn through data plans on thier iPads, and above all, they think. Also, they are generally incapable of speaking plain English when describing a premise upon which they are working, something that I loathe, since it is lazy minded of them, when you consider the feats of which thier minds are capable.

Then you have your common or garden physicist. His or her job is to actually interact with the universe directly, run experiments in the real world that may prove or disprove a theory, and lead to the formulation of new ones. They also deal with the hard point of applying physics to problems, like energy production and conservation, space flight, and so on. It is not unrealistic to say that they are people whose works actually become physically real, rather than remaining the stuff of mind. You dont tend to get theoretical physicists firing particles around a hadron collider, in the same way as you would not expect a prolific experimentor to be stood immobile before a blackboard, contemplating imponderables and talking in numeric riddles.

Originally posted by TrueBrit
Then you have your common or garden physicist. His or her job is to actually interact with the universe directly, run experiments in the real world that may prove or disprove a theory, and lead to the formulation of new ones. They also deal with the hard point of applying physics to problems, like energy production and conservation, space flight, and so on. It is not unrealistic to say that they are people whose works actually become physically real, rather than remaining the stuff of mind. You dont tend to get theoretical physicists firing particles around a hadron collider, in the same way as you would not expect a prolific experimentor to be stood immobile before a blackboard, contemplating imponderables and talking in numeric riddles.

Although you're post is generally accurate not all theoretical physicists do research in esoteric fields that never materialize. Perhaps, your description only applies to high energy theorists, but many theorists not in high energy do work on practical problems. Many theorists, for example, are employed in industry to work on cutting edge theoretical work in fields such as nanotechnology and quantum computing.

Originally posted by Moduli

Originally posted by ErosA433
Now i think in QCD you cannot have an unbound quark

That's true at low energies, yes, although at high energies you get a quark-gluon plasma which you can think of as made up of free quarks.

You asked where the energy comes from, it is i believe the binding energy of the proton

The energy to create the new particles comes from the initial kinetic energy plus the internal energy of the nucleons. It turns out it's not easy to estimate the details of internal energies of a real-life collider, and that's part of what makes it so difficult to analyze results from them (although it's easy enough to come up with idealized models where you can calculate that kind of thing, of course).

the model on its own does not contain mass as a predicable variable

That doesn't matter because that was never a requirement of the theory. And the Higgs doesn't determine all masses either, e.g., neutrino masses are probably determined by something like the seesaw mechanism. The Standard Model has many independent parameters whose values are only determined by experiment.

Yep pretty much how i was trying to explain each point though doing a bad job of it (typical scientist here lol)

My PhD was in neutrino physics, long baseline oscillation. And now Dark Matter. Thought id pop back onto the thread after the weekend and essentially say yep these points are correct for anyone else who might have doubt or be scratching their heads thinking mmmm.


The Quark Gluon plasma is essentially how we form jets, or get rapid hadronisation, the energy required to create the particles is essentially from the kinetic energy though I was trying to touch on that that energy is accessed via the mix of stuff that make up a particle rather than a simple billiard ball way of thinking. It can be imagined parhaps most classically if rather than a proton being a single ball, you had 3 balls bound together inside one ball, all 3 balls move with the net momentum of the whole, but also are semi-free to move with respect to each other, confined by a springy force that acts like a spring between all of the components. Hence as Moduli points out... its far more complicated than a simple billiard ball example. So naturally if you split this apart and you separate one of the quarks out, the energy it carries away is taken from the net kinetic energy, and the system assumes a quantum mechanically acceptable form, one that conserves required quantum numbers etc.

The mass as you said is not required by the theory though it can be determined by experiment via cross section suppression, in many ways in the 70s and 80s this is how the generations of particles were discovered and their mass first estimated. Though fundamentally the standard model does not contain mass. This is a blessing and a curse. An outside observer would look at it and say... well this is all well and good but, mass is sort of a gaping hole in the whole thing right? And they would be correct.

Also you are bang on about the neutrino, which according to current thinking requires a different mechanism. This is partly because the way that the theory is set up makes it tricky to have particles that have eV scale mass coupled to MeV scale masses. The seesaw mechanism comes in multiple types though basically requires a sterile/right handed/none interacting neutrino that couples at lower energies to give the observed small masses. The mass of this particle would be at the GUT scale. Once again, it is not a proven, but gives some interesting things to look for at low energies. This GUT scale particle is almost like a higgs for neutrinos... though the higgs is probably the mechanism for giving the particle mass in the end.


*sigh* While i said, QED, QCD and QFT are very interesting, anyone who has done it on paper... it aint pretty. I have several folders of that stuff and all of it sums up to one big brain melting headache.

Originally posted by ErosA433
*sigh* While i said, QED, QCD and QFT are very interesting, anyone who has done it on paper... it aint pretty. I have several folders of that stuff and all of it sums up to one big brain melting headache.

QED is pretty boring, QCD is messy, but QFTs in general are sexy. A lot of the structural things, especially, like Seiberg duality or BCFW are really cool. But, yeah, individual computations aren't too terribly exciting .

reply to post by transmundane


There's another school of thought that embraces the existence of "emergent systems" that do not possess the same physical attributes nor are they governed by the same natural laws as the systems that combined to cause them to emerge. One easy example of this notion is a ball. Not a manufactured ball, but a naturally formed ball (say of a ferrous material that formed as a result of molten material having gone through a rapid cooling event), since the specific material of the ball is unimportant.

What comes together to cause this ball to physically emerge as the material ball that it is, are atoms. This isn't controversial, so let's acknowledge that yes, the ball itself is made up of atoms. But atoms and the contributing particles and bosons that make up atoms are very different than this ball - even though the ball itself is made up of nothing but atoms. Atoms that are made up of nothing but particles and bosons. The laws that atoms, and the particles and bosons that make up atoms, obey are not the same natural laws that the ball itself obeys. They are completely different systems governed by completely different laws, and yet, they are not distinct from one another. The ball can't exist separate from the atoms (and particles and bosons) that create it and maintain its physical existence as the ball that it is. These are two completely different and unique systems that possess completely unique relationships with physical reality - an atom's relationship with reality is much different than an iron ball's relationship with the very same reality, and I think that we can all agree on that.

The ball is what physicists refer to as an "emergent system" since the systems that create it (the atom, which is a system unto itself) produce a system that is unique and in possession of its own physical characteristics, as well as its own set of governing principles relative to the reality that both systems share.

These "strings" exist as one system, and if they do exist, then they obviously exist as part of the contribution of systems that collect to cause the "emergence" of the kind of system that responds to what scientists have labeled The Standard Model. Obviously, there are many systems that respond to this Standard Model, and clearly these systems are much more readily identifiable than the systems that exist just beneath their emergence - bringing these identifiable systems into emergent existence.

So, if this Standard Model does exist (which is still open to debate) then String Theory isn't at all threatened. Emergence theory - which is much more represented in physics that most other theories - easily allows for both to coexist. Also, keep in mind that the Higgs Boson is only an indication - if anything - that only tacitly supports a specific interpretation (of why particles "slow down" enough to coalesce into larger collectives) that doesn't actually contribute much to what's known about the nature of physical reality, other than to be "the best guess we have" as to why only photons travel at the speed of light. And the Higgs Boson itself has repeatedly been redefined over the years, and that's a fact that has to be taken into account when anyone claims to have discovered it. In fact, what is meant by "discovering" it, is more a case of NOT discovering what theoretically should exist within certain parameters within a given collision, and even then, only for a split instance, before "disappearing" forever. So, given all that uncertainty, I'm kind of surprised that anyone has popped any champagne corks over what they think they might've NOT detected this last summer - after over a trillion collisions that revealed nothing (or rather NOT nothing, I guess).

All in all I wouldn't worry about String Theory. If it's true, it'll be just fine. If it's not true, then what difference does any of this make.

Originally posted by ErosA433
This is a plague for a theory because 99.99999% of the time, the infinity is not physical.

Actually 99.9999999 repeating, equalling 100%.