ChatterBank1 min ago
Cern Lhc2 What Will Be Discoverned?
The press has been hyping the re-opening of the LHC at CERN this week with an effective doubling of the energy of the proton.proton collisions.
Yes it would be nice to think that the secrets of the cosmos will be finally revealed to us. I'm not holding my breath however. Surely the only way to find these things out would be to recreate the 'big bang' itself. There is no way we can even dream of creating anything remotely close to that here on earth so why the hype?
Yes it would be nice to think that the secrets of the cosmos will be finally revealed to us. I'm not holding my breath however. Surely the only way to find these things out would be to recreate the 'big bang' itself. There is no way we can even dream of creating anything remotely close to that here on earth so why the hype?
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Travelling at the moment. Will try to get a comprehensive answer together this evening. Short answer though is "don't know" -- which is really the main point of the experiment. We have expectations of what we might find. If we do then we learn our theories are right. If not then we learn they are wrong. Either way we learn a great deal.
the short answer is, we don't know but I'd have thought that now Higgs has been confirmed they'd like to verify other Bosons that are currently theoretical, eg the Graviton. But it's just a voyage of discovery really. Many great inventions and discoveries have been serendipitous so we may yet discover useful stuff without really looking for specific things.
To the best of my knowledge there is no reason to expect the graviton to show up at the LHC. If indeed it exists and is the quantum of the gravitational field then I'd expect it to be visible at energy levels equivalent to the Planck scale, or about 10,000 million million times more energy than the LHC is capable of.
* * * *
To try to answer the question more fully, the LHC is basically going to achieve two things. First, it will strengthen our understanding of the Standard Model, allowing us to perform more accurate measurements and with better statistics than ever before. This is an important task still as some of the Standard Model theory predictions come with a level of uncertainty that is really quite large, close to 30% in some measurements. Better experimental data drives the theorists to work harder at tightening things up -- and the overall effect is to make anything new easier to see.
Second, then, the LHC is going to find, or almost entirely rule out, New Physics that would be expected to kick in at around the energy scales it's capable of probing. There are plenty of reasons to expect that it has to show up sooner or later, because the Standard Model is just obviously "wrong" -- as in, incomplete -- and it also makes a bit of sense on certain theoretical grounds that the next level of physics needed to fix the problems can't be at too high an energy scale.
I think in essence that means that LHC Run 2 is expected to find pretty much exactly the same things that LHC Run 1 was expected to find. That it didn't turn up in the first run may be a sign that it isn't going to turn up now, but in fact there are some hints that the LHC may have found something new. Or not, depending on how you interpret the data. Since RUn 2 is going to be operating at a higher energy, and will provide much more data overall, then any of these hints should become more visible, or turn out to be just statistical noise after all. IN the meantime the experimentalists will have gained useful experience with their detectors and should be improving their statistical analysis techniques so that if new stuff is there it will be easier to find.
With the discovery of the Higgs -- or a Higgs-like thing -- already in the bag, the next run should also start to probe and confirm various of its properties eg mass, charge, spin, parity, couplings to other particles, hopefully some extra decays it can do -- all of which go to provide a better confirmation of the Standard Model, or a better chance of finding what is missing from our current understanding.
So, again, to cut a long story short: more of the same at last time it was switched on, only with a better chance of finding things if they are actually there. And if it still finds nothing then the ruling out of everything new at about TeV scales would be a major shock to the physics community and a call for more new ideas.
* * * *
To try to answer the question more fully, the LHC is basically going to achieve two things. First, it will strengthen our understanding of the Standard Model, allowing us to perform more accurate measurements and with better statistics than ever before. This is an important task still as some of the Standard Model theory predictions come with a level of uncertainty that is really quite large, close to 30% in some measurements. Better experimental data drives the theorists to work harder at tightening things up -- and the overall effect is to make anything new easier to see.
Second, then, the LHC is going to find, or almost entirely rule out, New Physics that would be expected to kick in at around the energy scales it's capable of probing. There are plenty of reasons to expect that it has to show up sooner or later, because the Standard Model is just obviously "wrong" -- as in, incomplete -- and it also makes a bit of sense on certain theoretical grounds that the next level of physics needed to fix the problems can't be at too high an energy scale.
I think in essence that means that LHC Run 2 is expected to find pretty much exactly the same things that LHC Run 1 was expected to find. That it didn't turn up in the first run may be a sign that it isn't going to turn up now, but in fact there are some hints that the LHC may have found something new. Or not, depending on how you interpret the data. Since RUn 2 is going to be operating at a higher energy, and will provide much more data overall, then any of these hints should become more visible, or turn out to be just statistical noise after all. IN the meantime the experimentalists will have gained useful experience with their detectors and should be improving their statistical analysis techniques so that if new stuff is there it will be easier to find.
With the discovery of the Higgs -- or a Higgs-like thing -- already in the bag, the next run should also start to probe and confirm various of its properties eg mass, charge, spin, parity, couplings to other particles, hopefully some extra decays it can do -- all of which go to provide a better confirmation of the Standard Model, or a better chance of finding what is missing from our current understanding.
So, again, to cut a long story short: more of the same at last time it was switched on, only with a better chance of finding things if they are actually there. And if it still finds nothing then the ruling out of everything new at about TeV scales would be a major shock to the physics community and a call for more new ideas.
jim360
Brilliant and disarmingly honest response to my question.
Would it be wrong of me if I suggested that the symbolism of what CERN now stands for could turn out to be a noose round it's neck, given that as the hype has built up CERN, will have to find a way of justifying it's 'discoveries'/measurements in a way that will appease their political quartermasters?
Where from CERN is the populist pay-off going to come from when the EU is having to politically correctly allow the entire population of North Africa to come and live in Europe with it's sky-high levels of youth unemployment?
Brilliant and disarmingly honest response to my question.
Would it be wrong of me if I suggested that the symbolism of what CERN now stands for could turn out to be a noose round it's neck, given that as the hype has built up CERN, will have to find a way of justifying it's 'discoveries'/measurements in a way that will appease their political quartermasters?
Where from CERN is the populist pay-off going to come from when the EU is having to politically correctly allow the entire population of North Africa to come and live in Europe with it's sky-high levels of youth unemployment?
I guess it's possible. Although a negative result for new physics overall* might in some ways be even more spectacular it's very hard to sell a negative result as an achievement. Thomas Edison knew it: "I now know 15,000 things that don't work", I think he said about his efforts to find a working light-bulb filament. In the same way physicists might know several theories that don't work -- and a very rich range of ideas they are, in many respects -- so again a failure of those theories marks some new level of understanding, of a sort. But perhaps it will not be seen like that. If so, it's a risk worth taking.
Not really sure what the migrant crisis has to do with the picture though.
*The picture is unlikely to be as clear-cut as "no New Physics after all". More likely, there might be a set of clear experimental signs that something isn't quite right with the Standard Model, a few anomalies here and there that have not disappeared, but no resolution as to what exactly is filling the gap. Because also it is not at all a trivial thing to disentangle what is actually new physics from what is just some other background you hadn't considered, it's possible that the lack of discovery will just mean that the experiment wasn't controlled enough after all. If so, then it's hard to see what to do about that beyond switching to an electron-positron collider rather than a hadron collider. By a curious coincidence, exactly such a collider is potentially about to be commissioned over in Japan -- the International Linear Collider. I'm just reading up on its intended physics programme now and then I'll be back.
Not really sure what the migrant crisis has to do with the picture though.
*The picture is unlikely to be as clear-cut as "no New Physics after all". More likely, there might be a set of clear experimental signs that something isn't quite right with the Standard Model, a few anomalies here and there that have not disappeared, but no resolution as to what exactly is filling the gap. Because also it is not at all a trivial thing to disentangle what is actually new physics from what is just some other background you hadn't considered, it's possible that the lack of discovery will just mean that the experiment wasn't controlled enough after all. If so, then it's hard to see what to do about that beyond switching to an electron-positron collider rather than a hadron collider. By a curious coincidence, exactly such a collider is potentially about to be commissioned over in Japan -- the International Linear Collider. I'm just reading up on its intended physics programme now and then I'll be back.
https:/
It's volume two you want. This is the report that will have been submitted presumably to those people who are about to pay the bills, so it is naturally written with more than a little bias in favour of electron colliders over hadron ones, but it is also true that a lot of the advantages are real. It's also well over a hundred pages long and very quickly gets super-technical -- if you do glance over it please do ask any questions and I'll do my best to answer them.
Anyway, the search for new physics could, possibly, continue with a different type of collider; while the measurements of properties of currently-known physics could always benefit from some retuning.
For the record, I'll also quote verbatim the report's view of the situation at the LHC, and how they justify a further experiment in light of the apparent lack of results:
* * *
"The LHC has not yet provided evidence for signals of new physics beyond the Standard Model
from its early running at 7 and 8 TeV. There are two distinct attitudes to take toward the current situation. The first is that it is premature to draw any conclusions at the present time. The LHC experimental program is still in its early stages. The accelerator has not yet reached its design energy and has so far accumulated only 1% of its eventual data set. The second is that the discovery of the new scalar boson—especially if turns out to have the properties similar to the Standard Model Higgs boson—and the deep exclusions already made for supersymmetry and other new physics models have already changed our ideas about new physics at the TeV energy scale. Our information from the LHC is certainly incomplete. We look forward to new information and new discoveries in the LHC run at 14 TeV [note -- currently just 13TeV, with 14 TeV runs expected later on] that will take place in the latter years of this decade. And, yet, we must take seriously the implications of what we have already learned."
It then notes that there are three broad types of model, the first (basically Technicolour, which I think I name-dropped in the other thread) is already almost dead, although some people are still working on it anyway. The second, the LHC should be able to see itself but if it does then you'll need a new collider to run precision tests. The third, the LHC might not be able to rule out for good -- and again a new electron-positron collider could do the job instead. So I guess that means that the LHC need not mark the end of New Physics as we know it if nothing turns up. We'll see.
* * *
Incidentally, the effort that goes into designing, building and running these things also creates plenty of jobs at all levels. It's not just scientists employed at colliders. And the global collaborative effort to make these things work and get useful stuff out of them is not insignificant either. Science can be a great unifier, and is also pretty good for the economy. Perhaps depends on your perspective I suppose. At the very least, if you have money to throw away on giving physicists fancy little toys to play with then things can't be all that bad.
It's volume two you want. This is the report that will have been submitted presumably to those people who are about to pay the bills, so it is naturally written with more than a little bias in favour of electron colliders over hadron ones, but it is also true that a lot of the advantages are real. It's also well over a hundred pages long and very quickly gets super-technical -- if you do glance over it please do ask any questions and I'll do my best to answer them.
Anyway, the search for new physics could, possibly, continue with a different type of collider; while the measurements of properties of currently-known physics could always benefit from some retuning.
For the record, I'll also quote verbatim the report's view of the situation at the LHC, and how they justify a further experiment in light of the apparent lack of results:
* * *
"The LHC has not yet provided evidence for signals of new physics beyond the Standard Model
from its early running at 7 and 8 TeV. There are two distinct attitudes to take toward the current situation. The first is that it is premature to draw any conclusions at the present time. The LHC experimental program is still in its early stages. The accelerator has not yet reached its design energy and has so far accumulated only 1% of its eventual data set. The second is that the discovery of the new scalar boson—especially if turns out to have the properties similar to the Standard Model Higgs boson—and the deep exclusions already made for supersymmetry and other new physics models have already changed our ideas about new physics at the TeV energy scale. Our information from the LHC is certainly incomplete. We look forward to new information and new discoveries in the LHC run at 14 TeV [note -- currently just 13TeV, with 14 TeV runs expected later on] that will take place in the latter years of this decade. And, yet, we must take seriously the implications of what we have already learned."
It then notes that there are three broad types of model, the first (basically Technicolour, which I think I name-dropped in the other thread) is already almost dead, although some people are still working on it anyway. The second, the LHC should be able to see itself but if it does then you'll need a new collider to run precision tests. The third, the LHC might not be able to rule out for good -- and again a new electron-positron collider could do the job instead. So I guess that means that the LHC need not mark the end of New Physics as we know it if nothing turns up. We'll see.
* * *
Incidentally, the effort that goes into designing, building and running these things also creates plenty of jobs at all levels. It's not just scientists employed at colliders. And the global collaborative effort to make these things work and get useful stuff out of them is not insignificant either. Science can be a great unifier, and is also pretty good for the economy. Perhaps depends on your perspective I suppose. At the very least, if you have money to throw away on giving physicists fancy little toys to play with then things can't be all that bad.
On another thread I discussed the creation of a working anti-matter bomb. My biggest disappointment with the LHC appears now to be the justification for the next extravaganza of particle physics.
The signals were always going to be too messy and hard to interpret because the particles involved a) are not fundamental particles like the electron and b) because only through annhiliation of a fundamental particle and it's anti-particle can scientists truly observe e=mc2 in action. Also, due to the non-linear path of the particles at CERN the set-up there was obsolete before they even started re-inventing it.
None of this is coming out in the press yet but it should, just like FIFA.
So now, what a surprise a huge linear accelerator firing anti-matter positrons at electrons as before but now linear and now in Japan!
Much as I'm curious to see what claims the spoilt brat bamboozelers will claim necessitates this huge expenditure I have to ask Japan (Ring of Fire) really, or is the money more important than the science?
The signals were always going to be too messy and hard to interpret because the particles involved a) are not fundamental particles like the electron and b) because only through annhiliation of a fundamental particle and it's anti-particle can scientists truly observe e=mc2 in action. Also, due to the non-linear path of the particles at CERN the set-up there was obsolete before they even started re-inventing it.
None of this is coming out in the press yet but it should, just like FIFA.
So now, what a surprise a huge linear accelerator firing anti-matter positrons at electrons as before but now linear and now in Japan!
Much as I'm curious to see what claims the spoilt brat bamboozelers will claim necessitates this huge expenditure I have to ask Japan (Ring of Fire) really, or is the money more important than the science?
I'm not sure what you mean by "obsolete". A bit bizarre. The LHC is the most un-obsolete experiment ever performed.
The backgrounds and general mess are huge but it is possible to isolate signals and extract meaningful physics. Most spectacularly of course you have the Higgs boson but the papers on these represent a fraction of the total and the various CERN experiments have been publishing something like 100 papers a year each since 2009 (I'll check the exact figure later but for whatever reason the site I was going to use to check this figure on has gone down). And the wider community has published a few thousand more papers of varying importance on top of all that. Because they are focused on the less eye-catching parts of physics they tend to get ignored, but much useful work has come out of the LHC all the same.
Nor is a Linear Collider meant as a replacement. The intention is to complement the work of the LHC. A somewhat crude analogy is that the LHC is great for discovering things and a high-energy linear collider is great for then measuring their properties.
The ILC isn't a surprise earlier. The technical report I linked to earlier was published two or three years ago, and the idea has been bouncing around for a while before that. All in the public domain, but because nothing had been decided (and still hasn't, we await a decision from the Japanese government) then it hadn't yet received much attention by the press. Not a secret project, though.
"Also, due to the non-linear path of the particles at CERN the set-up there was obsolete before they even started re-inventing it. "
The non-linear path is quite important really. To accelerate particles up to the energies required you could do it linearly but then you need a rather long tunnel. Wrap it around in on itself and you can make the particles to several laps, speeding up each time. Apart from the slightly annoying issue of synchrotron radiation this is a very good way of getting to the high energies needed for the next stage of discovery. Or not -- but we'll hopefully be finding out one way or another very soon.
The backgrounds and general mess are huge but it is possible to isolate signals and extract meaningful physics. Most spectacularly of course you have the Higgs boson but the papers on these represent a fraction of the total and the various CERN experiments have been publishing something like 100 papers a year each since 2009 (I'll check the exact figure later but for whatever reason the site I was going to use to check this figure on has gone down). And the wider community has published a few thousand more papers of varying importance on top of all that. Because they are focused on the less eye-catching parts of physics they tend to get ignored, but much useful work has come out of the LHC all the same.
Nor is a Linear Collider meant as a replacement. The intention is to complement the work of the LHC. A somewhat crude analogy is that the LHC is great for discovering things and a high-energy linear collider is great for then measuring their properties.
The ILC isn't a surprise earlier. The technical report I linked to earlier was published two or three years ago, and the idea has been bouncing around for a while before that. All in the public domain, but because nothing had been decided (and still hasn't, we await a decision from the Japanese government) then it hadn't yet received much attention by the press. Not a secret project, though.
"Also, due to the non-linear path of the particles at CERN the set-up there was obsolete before they even started re-inventing it. "
The non-linear path is quite important really. To accelerate particles up to the energies required you could do it linearly but then you need a rather long tunnel. Wrap it around in on itself and you can make the particles to several laps, speeding up each time. Apart from the slightly annoying issue of synchrotron radiation this is a very good way of getting to the high energies needed for the next stage of discovery. Or not -- but we'll hopefully be finding out one way or another very soon.
I was trying to remember the German word for it-Bremsstrahlung i.e. 'braking radiation. More of a hindrance in attempts to accelerate particles as close to c as possible, but useful for other purposes. Yes a ring allows bunches of particles to be built up and stored ready to be collided at the specific points around the ring where the massive detectors are located.
CERN is an engineering marvel and I personally have nothing but respect for it and the many discoveries it has made over it's long life. My concerns stem from anxiety about how the mass population of the participating states view the costly project when many of us feel beset with other more serious and pressing problems like the war and poverty driven- mass migrations of human populations as I touched on above.
The attitude of the metropolitan elite who control the 'quality' press and TV in this country is at best minimalistic and doesn't go deep enough to explain the experiments and give more insight into the fascinating history of particle physics. I remember when CERN was chasing down the quark generations and discovering the W and Z bosons the BBC actually did a two hour special on a Sunday afternoon. I had to go to a friend's house to watch it as the rest of my family wanted to watch the Muppet show on ITV!
It would be great to have a long linear accelerator with a ring at each end with bunches of tauons built up at one end and anti-tauons at the other. I hope it happens though Japan with it's earthquakes (approx. 1500pa) wouldn't be my choice. I imagine CERN could be turned into a pretty good all-year round running or cycling track when it's illustrious career ends!
CERN is an engineering marvel and I personally have nothing but respect for it and the many discoveries it has made over it's long life. My concerns stem from anxiety about how the mass population of the participating states view the costly project when many of us feel beset with other more serious and pressing problems like the war and poverty driven- mass migrations of human populations as I touched on above.
The attitude of the metropolitan elite who control the 'quality' press and TV in this country is at best minimalistic and doesn't go deep enough to explain the experiments and give more insight into the fascinating history of particle physics. I remember when CERN was chasing down the quark generations and discovering the W and Z bosons the BBC actually did a two hour special on a Sunday afternoon. I had to go to a friend's house to watch it as the rest of my family wanted to watch the Muppet show on ITV!
It would be great to have a long linear accelerator with a ring at each end with bunches of tauons built up at one end and anti-tauons at the other. I hope it happens though Japan with it's earthquakes (approx. 1500pa) wouldn't be my choice. I imagine CERN could be turned into a pretty good all-year round running or cycling track when it's illustrious career ends!
Not convinced it's realistic to expect a tauon collider at any time -- they decay rather to quickly to build up in any numbers -- but a muon collider, the middle brother in the lepton family, is sometimes mentioned as a real possibility and is currently being seriously investigated. If that could be realised it would have many advantages over electron colliders, including significantly less bremsstrahlung (or synchrotron radiation if it's a circular muon collider, which it probably will be). The main problem is that it's harder to set up, muons also being unstable. So far as I can tell, work on designing even the concept is ongoing.
Only the electron of the trio is stable at non-relatavistic velocities. In non-relatavistic hadrons the proton is stable but neutrons decay in around five minutes in isolation. Muons too, but the reason they can be detected in cosmic rays is because of the time dilating effect of travel close to the speed of light stopping their decay. The same would apply to the mighty tauon if they could be accelerated fast enough to become stable enough to be set on a near c collision course with their corresponding antiparticle. Now imagine what you could unambiuously discover from that little big bang!
True, and the discovery potential of a tauon collider would be interesting indeed. But the lifetime of the tau is about ten million times shorter than that of the muon so the challenge of keeping it stable enough to collide is about ten million times harder. It is an idea worth bearing in mind perhaps but probably something for the far future. By which time easier collider experiments should have been productive anyway.
One on my nieces is a physicist. A linear cascade reactor would do it maybe, but I need to ask someone much more knowledgeable than me. Gives me an excuse to ping her an email anyway.
Our semi-feral now neutered tom Billie is making slow progress as we tend his corneal ulcer having rubbed our hands with an appeasing pheromone spray called Feliway and an antibiotic injection that blessedly lasts two weeks called Convenia. Slow but undoubted progress, kind of like the matter under discussion!
Our semi-feral now neutered tom Billie is making slow progress as we tend his corneal ulcer having rubbed our hands with an appeasing pheromone spray called Feliway and an antibiotic injection that blessedly lasts two weeks called Convenia. Slow but undoubted progress, kind of like the matter under discussion!
They've already discovered it, and that is the need to build another more powerful particle accelerator in Japan! Jobs for the boys, the show must go on!
Not more to add on the Tuaon issue for now. At least the presence of relativistic Muons in cosmic rays arriving on Earth suggests a possibility they could be considered. How would you make anti-muons on demand though however? It's going to have to be as it was before namely electrons and positrons and the hope that they can push them closer to c than ever before.
Not more to add on the Tuaon issue for now. At least the presence of relativistic Muons in cosmic rays arriving on Earth suggests a possibility they could be considered. How would you make anti-muons on demand though however? It's going to have to be as it was before namely electrons and positrons and the hope that they can push them closer to c than ever before.
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