Correct.
The shutdown was originally planned to start a month or so ago, but the run got extended to make sure we had the maximum number of collisions to sudy the Higgs boson in detail. It could not be extended more, because of issues with contracts planned long ago for this shutdown.
The LHC performed very well this year, but not above its own expectations, and therefore we have now a dataset which is big enough to say a few words about how this boson really looks like the Higgs boson, but to really characterize it further we need more data. For instance, with the data still being analysed, we know that the spin will not be unambiguously determined - well, depends on the definition; at least not with the usual 5 sigma.
Cooling and magnets take the largest chunk. At full power it consumes about the power of a small-to-midsize city, like neighbouring Geneva, Switzerland.
I'm not sure I understand what you mean. But one way out of the problem is indeed that the universe is a little different than we think we are observing. The proposal of extra dimensions that make the apparent very high gravity scale much smaller in the theory removes the unnaturalness problem as well. However, this nor other solutions are fully satisfactory either, and supersymmetry remains to be one of the best possibilities - though nature might have something completely different in stock for us.
The standard model as a theory on its own needs extreme fine tuning to be valid all the way up to the scale where gravity becomes strong. Technically, there is a quadratic dependence on the upper scale of the theory when one calculates the quantum corrections to the Higgs mass. This leaves the theory very unnatural (even though mathematically not impossible).
Supersymmetry solves this naturalness problem by canceling the quadratic divergences. It cannot cancel exactly though (or we'd have observed supersummetry since long), so therefore a new unnaturalness problem arises when supersymmetry lives at an energy scale far above the scale of electroweak symmetry breaking (~the Higgs boson mass scale).
Bull shit. See my reply to the parent for the LHC black hole connection.
Here's a paradox for you. You say: If there's no reason to assume they are not equally likely, then they are. Equally valid must be: if there's no reason to assume they are equally likely, then they are not. Since there is indeed no reason to assume either, they are both equally and not equally likely. Oops, logic fail.
I found your comment amusing, until I thought: hey, this thought that physicists are crazy is why conversation so often stops when I say I'm a physicist.
This is reality we're talking about after all (except for the many worlds, that is philosophy). Nature may be bizarre, but it shapes our world so much (got a celullar phone or GPS?) that a "smoking dope" reaction is not helping.
Can we call it fascinating instead please?
Science education still has a long way ahead...
When I moved to the US, I didn't know I would pay to get a phone call. I found that out _after_ I got me a phone and plan and all. One of those things that made it a little harder to adapt than I expected. Because it just doesn't make sense:-).
And I never got used to it.
Actually, two independent experiments, with on purpose different technological choices, blinded their data until a little before the announcement. Once the box was opened, on both sides the evidence for a new particle emerged, independently. TFS mentioned there are 2 teams: ATLAS and CMS.
Btw, would you read my comment differently if you knew I had a PhD or not?
It's not about trust. The fact that irreproducible results happen does not mean that all science is bad (was that a computer full of quantum mechanics you used to type that comment?).
Well, to start with, there are two independent experiments.
And secondly, from experience, those few peer reviewers can still ask damn good questions, even about papers signed by ~3000 authors.
Nope, it isn't. It's a boson, that's for sure, but its properties are not very well established yet. It really looks like a Higgs boson, or something quite similar, but that will take more measurement to tell for sure.
Eg: we're not certain yet whether it has spin 0 (like a Higgs boson should have), or spin 2.
Oh, you get me wrong, I agree with you. The subtle difference is important (that's why it is made). Since you said that we "haven't seen of the other properties yet" (except mass and longevity), I'm just pointing out that we know quite a bit more (but not enough to claim it to be the Higgs boson, and not with enough precision yet). It even got modded informative; probably because it is.
No reason to start shouting. I'm not blaming nor arguing.
But since you got me a bit cranky, let me point out though, that "the mass and longevity are consistent with predicted values for the Higgs." is incorrect. First of all, we had no prediction for the mass, unless you assumed the Standard Model to be self-consistent, in which case the electroweak precision data predicted it to be light, at ~90GeV, with a big error bar. Second of all, we don't know much about the longevity, we can only place upper bounds. The decay widths of the states we see in the high-precision 2photon and ZZ decay channels are dominated by detector resolution, so we have no access to the natural width of the resonance, which carries the information of the longevity. The natural width for a standard model Higgs boson at the observed mass is actually very small, far out of the LHC's reach.
I have to bring it to the open: Scientific Linux sucks!
At least on the desktop.
It's so ancient, but then... also super stable. And that is crucial for all our online and offline computing needs.
Don't we all (at CERN) still have some SLC4, even SLC3, systems around? Upgrades are so painful, especially when hardware is in the game...
Ok, I should carefully re-read what I wrote; I'm new here;-)
Yes of course, he thinks finding it matters a lot; he celebrated so I read in my home-country newspaper.
So yes, it's the second - he was convinced it was out there to be found anyway.
And the prof is a theorist, post-doc'd with the pioneers of supersymmetry, and then drifted off into string theory. Yes, that gets close to math...
We do know some of its properties already. We know that it has integer spin, hence is a boson, or we wouldn't see it decay in two photons. We have good evidence that it is the first spin zero, so scaler, fundamental particle ever observed, from the way the signal builds up in the WW decay channel, where the analysis uses the 0-spin property to enhance sensitivity. We also know that the production x decay probabilities are close to what one would expect from a standard-model Higgs boson. Especially the latter is something strong: we set out to detect something very peculiar, and looked on a big sand beach for just a few very peculiar grains of sand - and it turned out we found something. You are correct, that we have to understand the properties, but it is not so much that we need to see if it is a Higgs boson, or something totally different, but rather whether it could possibly be a Higgs boson, or an imposter that looks very much like it and induces the same effects on nature. Theorists have already started to speculate: http://arxiv.org/abs/1207.1093
This is actually interesting. I got the electro-weak symmetry breaking theory in my 4th year of university (physics, of course). It was thaught as an essential ingredient of the Standard Model, which it is. But in a sense the absence of the Higgs boson discovery at that time was not considered so important. The underlying physics has effectively already been absorbed into the university physics curriculum.
Yes and no.
There was a lot of "that's how science works". Good.
However, I advise you to read: http://profmattstrassler.com/articles-and-posts/particle-physics-basics/neutrinos/neutrinos-faster-than-light/opera-what-went-wrong/ People resigned. That shouldn't happen if it's just science at works. Also, the dynamics in the authorlist of the Opera articles in question are interesting from the sociological point of view.
Another bad thing in my opinion was the CERN involvement, which I still don't understand. This was not a CERN experiment, nevertheless CERN chose to profusely communicate on the issue.
And, a scientific fuck up or not, that's how it will remain to be perceived by the outside...
Not so much we have ass-hats in our community (well, we do, of course;-)), but more that if we fuck up, like happened recently with the FTL neutrinos (not a CERN experiment), it might mean the end of the field, and the end of all of our academic and scientific careers. Going public with this is a big thing. Therefore our internal peer review is extremely intense: hundreds of people trying to shoot down observations from all sides. And what remains is rock solid. Science at its best.
We have two independent experiments, with different techologies, different people, even a different culture.
We were getting close because we had seen hints last year, which needed confirmation with more data. That's how it goes with a statistics.
It is false to say we just got to the end of the list. It was always clear that if the particle was there, we would first rule it out in all other mass ranges, before we would be able to establish it at its current mass. Again, that is how it works with statistics: we talk of exclusion when 5% chance remains we missed it; we talk of discovery only when we are really really damn totally sure statistics is not fooling us.
It is also false that it was a process of elimination. There was a perfectly viable option of not finding anything at all. It would have been a PR catastrophy, but a scientific breakthrough as well.
And if you're skeptical about statistics: quantum mechanics is all about probabilities, so live with it. Your phone works because of it.
You're wrong: it is established to be a boson, because it has been observed to decay to 2 photons. (because of spin)
You're wrong again: it cannot be something entirely different. Except for the mass, we knew exactly how it would be produced and decay. So, keeping only the mass as unknown, we went and search in those billions of collisions for very peculiar signatures, matching what we expected it to look like after decay. And guess what, we managed to find it exactly there, the decays kind-of matching with our expectation, across several channels and in two independent experiments. If you here a physicist say "we have to understand better the nature of the particle", it means we have to understand if it is the standard model Higgs boson, or something very much related, with properties slightly different because of new physics at higher enerrgy levels we don't know about yet. With what we have seen, noone in the field doubts about that we were and are on the right track.
Btw, we also almost certainly established it's a scalar (the only fundamental scalar we know), and not a spin-2 particle, because of what we see in the WW decay mode.
The existence of the scalar Higgs field as the explanation of electroweak symmetry breaking, implies the existence of the hierarchy problem:
http://en.wikipedia.org/wiki/Hierarchy_problem
So except for measuring all the particles' properties, which especially in case of the self-coupling will take many years, we will have to find an answer to the hierarchy problem. Hopefully that can come in the form of new physics, which is likely to also influence the Higgs boson properties like production and decay rates.
Slashdot Mirror
Correct.
The shutdown was originally planned to start a month or so ago, but the run got extended to make sure we had the maximum number of collisions to sudy the Higgs boson in detail. It could not be extended more, because of issues with contracts planned long ago for this shutdown.
The LHC performed very well this year, but not above its own expectations, and therefore we have now a dataset which is big enough to say a few words about how this boson really looks like the Higgs boson, but to really characterize it further we need more data. For instance, with the data still being analysed, we know that the spin will not be unambiguously determined - well, depends on the definition; at least not with the usual 5 sigma.
Cooling and magnets take the largest chunk. At full power it consumes about the power of a small-to-midsize city, like neighbouring Geneva, Switzerland.
I'm not sure I understand what you mean. But one way out of the problem is indeed that the universe is a little different than we think we are observing. The proposal of extra dimensions that make the apparent very high gravity scale much smaller in the theory removes the unnaturalness problem as well. However, this nor other solutions are fully satisfactory either, and supersymmetry remains to be one of the best possibilities - though nature might have something completely different in stock for us.
The standard model as a theory on its own needs extreme fine tuning to be valid all the way up to the scale where gravity becomes strong. Technically, there is a quadratic dependence on the upper scale of the theory when one calculates the quantum corrections to the Higgs mass. This leaves the theory very unnatural (even though mathematically not impossible).
Supersymmetry solves this naturalness problem by canceling the quadratic divergences. It cannot cancel exactly though (or we'd have observed supersummetry since long), so therefore a new unnaturalness problem arises when supersymmetry lives at an energy scale far above the scale of electroweak symmetry breaking (~the Higgs boson mass scale).
Even more interesting: is that Kelvin or Celcius?
Bull shit. See my reply to the parent for the LHC black hole connection.
Here's a paradox for you. You say: If there's no reason to assume they are not equally likely, then they are. Equally valid must be: if there's no reason to assume they are equally likely, then they are not. Since there is indeed no reason to assume either, they are both equally and not equally likely. Oops, logic fail.
Bang on.
In the days of the start up of the LHC, a certain Walter L. Wagner was estimating a 50% chance of the world collapsing into a black hole at LHC turn on.
Watch the daily show video linked here: http://blogs.discovermagazine.com/cosmicvariance/2009/05/01/daily-show-explains-the-lhc/
Walter enters at 2'30''. The probability lesson comes at ~3'30''.
I found your comment amusing, until I thought: hey, this thought that physicists are crazy is why conversation so often stops when I say I'm a physicist.
This is reality we're talking about after all (except for the many worlds, that is philosophy). Nature may be bizarre, but it shapes our world so much (got a celullar phone or GPS?) that a "smoking dope" reaction is not helping.
Can we call it fascinating instead please?
Science education still has a long way ahead...
When I moved to the US, I didn't know I would pay to get a phone call. I found that out _after_ I got me a phone and plan and all. One of those things that made it a little harder to adapt than I expected. Because it just doesn't make sense :-).
And I never got used to it.
Aye on the repeal request.
But I'm a Belgian, living in France. If you love fries in France, then you have never been to Belgium.
Now get off my lawn.
Actually, two independent experiments, with on purpose different technological choices, blinded their data until a little before the announcement. Once the box was opened, on both sides the evidence for a new particle emerged, independently. TFS mentioned there are 2 teams: ATLAS and CMS.
Btw, would you read my comment differently if you knew I had a PhD or not?
It's not about trust. The fact that irreproducible results happen does not mean that all science is bad (was that a computer full of quantum mechanics you used to type that comment?).
Well, to start with, there are two independent experiments.
And secondly, from experience, those few peer reviewers can still ask damn good questions, even about papers signed by ~3000 authors.
The choice of journal is very intentional.
Btw, a broader-scientist-public Science article is in the works.
Nope, it isn't. It's a boson, that's for sure, but its properties are not very well established yet. It really looks like a Higgs boson, or something quite similar, but that will take more measurement to tell for sure.
Eg: we're not certain yet whether it has spin 0 (like a Higgs boson should have), or spin 2.
Oh, you get me wrong, I agree with you. The subtle difference is important (that's why it is made). Since you said that we "haven't seen of the other properties yet" (except mass and longevity), I'm just pointing out that we know quite a bit more (but not enough to claim it to be the Higgs boson, and not with enough precision yet). It even got modded informative; probably because it is.
No reason to start shouting. I'm not blaming nor arguing.
But since you got me a bit cranky, let me point out though, that "the mass and longevity are consistent with predicted values for the Higgs." is incorrect. First of all, we had no prediction for the mass, unless you assumed the Standard Model to be self-consistent, in which case the electroweak precision data predicted it to be light, at ~90GeV, with a big error bar. Second of all, we don't know much about the longevity, we can only place upper bounds. The decay widths of the states we see in the high-precision 2photon and ZZ decay channels are dominated by detector resolution, so we have no access to the natural width of the resonance, which carries the information of the longevity. The natural width for a standard model Higgs boson at the observed mass is actually very small, far out of the LHC's reach.
I have to bring it to the open: Scientific Linux sucks!
At least on the desktop.
It's so ancient, but then... also super stable. And that is crucial for all our online and offline computing needs.
Don't we all (at CERN) still have some SLC4, even SLC3, systems around? Upgrades are so painful, especially when hardware is in the game...
Ok, I should carefully re-read what I wrote; I'm new here ;-)
Yes of course, he thinks finding it matters a lot; he celebrated so I read in my home-country newspaper.
So yes, it's the second - he was convinced it was out there to be found anyway.
And the prof is a theorist, post-doc'd with the pioneers of supersymmetry, and then drifted off into string theory. Yes, that gets close to math...
We do know some of its properties already. We know that it has integer spin, hence is a boson, or we wouldn't see it decay in two photons. We have good evidence that it is the first spin zero, so scaler, fundamental particle ever observed, from the way the signal builds up in the WW decay channel, where the analysis uses the 0-spin property to enhance sensitivity. We also know that the production x decay probabilities are close to what one would expect from a standard-model Higgs boson. Especially the latter is something strong: we set out to detect something very peculiar, and looked on a big sand beach for just a few very peculiar grains of sand - and it turned out we found something. You are correct, that we have to understand the properties, but it is not so much that we need to see if it is a Higgs boson, or something totally different, but rather whether it could possibly be a Higgs boson, or an imposter that looks very much like it and induces the same effects on nature. Theorists have already started to speculate: http://arxiv.org/abs/1207.1093
This is actually interesting. I got the electro-weak symmetry breaking theory in my 4th year of university (physics, of course). It was thaught as an essential ingredient of the Standard Model, which it is. But in a sense the absence of the Higgs boson discovery at that time was not considered so important. The underlying physics has effectively already been absorbed into the university physics curriculum.
And awful color choices...
Yes and no.
There was a lot of "that's how science works". Good.
However, I advise you to read: http://profmattstrassler.com/articles-and-posts/particle-physics-basics/neutrinos/neutrinos-faster-than-light/opera-what-went-wrong/
People resigned. That shouldn't happen if it's just science at works. Also, the dynamics in the authorlist of the Opera articles in question are interesting from the sociological point of view.
Another bad thing in my opinion was the CERN involvement, which I still don't understand. This was not a CERN experiment, nevertheless CERN chose to profusely communicate on the issue.
And, a scientific fuck up or not, that's how it will remain to be perceived by the outside...
Not so much we have ass-hats in our community (well, we do, of course ;-)), but more that if we fuck up, like happened recently with the FTL neutrinos (not a CERN experiment), it might mean the end of the field, and the end of all of our academic and scientific careers. Going public with this is a big thing. Therefore our internal peer review is extremely intense: hundreds of people trying to shoot down observations from all sides. And what remains is rock solid. Science at its best.
We have two independent experiments, with different techologies, different people, even a different culture.
We were getting close because we had seen hints last year, which needed confirmation with more data. That's how it goes with a statistics.
It is false to say we just got to the end of the list. It was always clear that if the particle was there, we would first rule it out in all other mass ranges, before we would be able to establish it at its current mass. Again, that is how it works with statistics: we talk of exclusion when 5% chance remains we missed it; we talk of discovery only when we are really really damn totally sure statistics is not fooling us.
It is also false that it was a process of elimination. There was a perfectly viable option of not finding anything at all. It would have been a PR catastrophy, but a scientific breakthrough as well.
And if you're skeptical about statistics: quantum mechanics is all about probabilities, so live with it. Your phone works because of it.
You're wrong: it is established to be a boson, because it has been observed to decay to 2 photons. (because of spin) You're wrong again: it cannot be something entirely different. Except for the mass, we knew exactly how it would be produced and decay. So, keeping only the mass as unknown, we went and search in those billions of collisions for very peculiar signatures, matching what we expected it to look like after decay. And guess what, we managed to find it exactly there, the decays kind-of matching with our expectation, across several channels and in two independent experiments. If you here a physicist say "we have to understand better the nature of the particle", it means we have to understand if it is the standard model Higgs boson, or something very much related, with properties slightly different because of new physics at higher enerrgy levels we don't know about yet. With what we have seen, noone in the field doubts about that we were and are on the right track. Btw, we also almost certainly established it's a scalar (the only fundamental scalar we know), and not a spin-2 particle, because of what we see in the WW decay mode.
The existence of the scalar Higgs field as the explanation of electroweak symmetry breaking, implies the existence of the hierarchy problem:
http://en.wikipedia.org/wiki/Hierarchy_problem
So except for measuring all the particles' properties, which especially in case of the self-coupling will take many years, we will have to find an answer to the hierarchy problem. Hopefully that can come in the form of new physics, which is likely to also influence the Higgs boson properties like production and decay rates.