So, the magic number here was 5σ, the generally accepted "gold standard" for discovery, which would mean a 1 in 1.74 million chance that the results occurred by chance rather than being a signal. As other commenters have pointed out, the presenter originally announced a 4.1σ observation, then continued to add data from other experiments until the combined result was 5.1σ. However, right at the end, he added in some additional data which actually brought the significance down to 4.9σ... That's science - you can't ignore data just because it ruins your big presentation.
IANAPhysicist, but I'd be interested to know how strict the 5-sigma discovery rule is considered - for example, could they still get a Nobel prize for a 4.9σ announcement? I suppose it's not that big a deal - the LHC is still running, and I'm sure they'll have enough data for a true 5σ announcement soon. Regardless, hats off to all involved, it must be exciting to be at the forefront of human knowledge :)
To be explicit, since this comment is still top voted: This comment was made by someone who only watched the first of 2 presentations.
The second presentation showed a 5 sigma result.
I'm Incredibly disappointed by the trivial inaccuracy of comments on hacker news lately, and that corrections never get upvoted quickly enough to prevent the spread of misinformation.
> which would mean a 1 in 1.74 million chance that the results occurred by chance rather than being a signal
No!! It's the chance that randomness could produce a result that large. This distinction sounds pedantic, but misunderstanding this is widespread and leads to fallacies committed frequently by very smart people who ought to know better in many fields.
The 5σ convention is more about announcement than about discovery. No one can really say when a discovery is made. As more information comes in, the image can remain fuzzy or can get clearer and clearer. In the latter case, 5σ is a convention as a threshold for when you are entitled to announce a discovery without being blamed for jumping the gun. They'll collect data for many more years before passing the threshold of Nobel-worthy discovery.
5σ is not a rule. It's just a measurement of the probability that the result you observe is an accident. It means that it's very unlikely that it was just pure luck.
By the way, σ measurements are also used in many engineering jobs, and quality systems measurements. The kind of industry "goal" is to get 6σ (let's say when you manufacture consumer goods in large quantities, like millions every month). But for some other industries, 9σ is the benchmark - and from what I know, air companies have quality systems up to 9σ to ensure the lowest risk of something wrong happening.
>IANAPhysicist, but I'd be interested to know how strict the 5-sigma discovery rule is considered - for example, could they still get a Nobel prize for a 4.9σ announcement?
It's very much a HEP thing, and done that way because HEP is pretty much all statistical analysis these days. Other fields wouldn't treat the sigmas as the most important thing, and I've heard mutterings that it's not really the most accurate approach - but it is objective and easy to apply.
5σ seems like an unnecessarily high standard to this non-physicist; what's the rationale for that? At 5σ we could publish 1,000 major discoveries a year and have E[false discovery accepted] = 1,740 years.
I've given up. Considering how this is supposed to be a big announcement which is probably important for a number of reasons that may affect a lot of people. I am surprised he didn't start with:
"I know a lot of people are tuning in without degree's in Physic's. Let me break it down for you in Leymens terms. We are fairly certain we have discovered this. It is important because of that. Now let me get onto why we think this."
I get that this talk is not meant for me. However, it is important - apparently. Its on the front page of Guardian.
If this is an announcement of great importance and it is 98% mumbo jumbo aimed at high end Physicists or whatever then.. I don't know. Its another chance to get people interested in science that has been missed.
Note: I am not saying the whole talk should be dumbed down. I am just saying a 2-3 minute prefix for those who do not understand a single word for the first 20 minutes of the presentation.
I am a particle physicist. The most interesting point of this announcement for me is that this is a confirmation of predictions of a very exotic particle.
The properties of subatomic particles include something called 'spin' - that's a fundamental quantum mechanical property. The higgs boson is the first elementary (i.e. not made of other particles) spin-less particle that we've discovered; it's completely unlike anything that we've seen up until now.
That the model that we have constructed can accurately predict its existence and the way that it decays without having observed anything like that beforehand is a huge confirmation that we're in the right region of model space. Today seems to be a huge confirmation that out understanding of physics is not fundamentally broken.
That's why its important; the prediction is like attempting a 5-point dive and nailing it pretty much perfectly. It's an impressive confirmation of 50 years of theoretical work.
(The anarchist in me would have preferred them not to find anything, I must admit. That would have been much more interesting, as the standard model came tumbling down... :-)
Even the Guardian reporter has admitted that it goes over her head. Heck, I'm doing a Master's in condensed-matter physics and I don't understand much of the jargon.
What I can tell you is, the parts which sound the most intimidating are actually probably the simplest bits. CERN operates a particle accelerator -- this means that the LHC basically smacks subatomic particles into each other at absurdly high speeds to create infinitesimal explosions with tremendous amounts of energy (these are the TeV, GeV numbers that you see -- they're talking about the amount of energy that was concentrated in the explosion). The explosion essentially disrupts the underlying fields of the universe so much that new particles can be created or destroyed, but if you excite the Higgs field to its quantizing particle, it tends to immediately decay into other things.
The other things are subatomic particles, including quarks (the letters u, d, c, s, t, and b for up, down, charm, strange, top and bottom -- you may have heard him for example say 'bb') and bosons (he talked a bit about W W* and gamma-gamma; gamma rays are light while W bosons are, well, a little more complicated let's say).
All of the stuff he says about Monte Carlo and so on is about creating "expected" curves from the Standard Model. You want to have two curves, "expected" vs. "actual", so that you can compare them.
On the base axis usually there is energy -- this is the energy of the explosion. There are usually two curves from Monte Carlo which tell you what you expect to see. Then there are data points with error bars which tell you what's actually seen and what the statistical "counting" errors are, how weak the signal is. Usually there is then a follow-up graph where they have tried to "subtract out the noise" to see the signal more clearly.
This is for the scientific community. The scientific method is that all results should be scrutinized, tested and verified. If you want a 2-3 minute explanation. Wait for CNN.
The ATLAS lady has what I think must be the worst set of powerpoint slides I've ever seen. Epically bad. Pretty amazing.
Even if you are working at CERN running the equipment, there's no way you could absorb all the info on each of those slides in the 10 to 15 seconds she shows them. They might as well have pictures of frolicking kittens on them.
That'll happen, someone will explain it in "layman" terms about why/how this is fundamentally important. That's probably not going to be done at this announcement though, but hopefully in the aftermath by the media reporting on the announcement.
The error bars on the mass range are typically just 1 sigma, so there's considerable overlap between the two figures (the Atlas figure is within the 95% confidence interval for the CMS figure, for example).
I love how we're using Hacker News here -- this is definitely not what it was designed for. What we're really doing is something like a live chat room while watching a common talk, but unlike chat rooms it can be threaded and points can be allocated. Also unlike a chat room, HN does not automatically update when we get new discussion messages, but that's a constraint of the technologies at the time it was built.
It might be very interesting to try to use comet-casting or websockets to revolutionize chat in precisely that way, realtime threaded discussions. So, in addition to all of the chat constraints you have the ability to dynamically mark certain chat messages as replying to other messages, and as the noise in the chat room gets higher you can filter yourself to just "I want to follow this discussion."
Really striking what a large percentage of the words are jargon. Sometimes I understand less than 10% of the words in a sentence. I think I might now better understand how a non-programmer feels when seeing a talk related to programming.
If you're going to make an announcement that is going to be held up to the highest rigorous standards, figuring out exactly what to say is going to be a difficult issue. This presentation isn't for you, this is for the physics community.
Next time you do a major presentation on state-of-the-art high-energy physics experiments live to a world-wide community on what could be a Nobel Prize winning event, let us know and we'll watch you do it better. ;)
Sounds like the kind of content that is just very hard to condense into a reasonable amount of time. This seems super dense to me, but you can imagine to a physicist this is a high level overview.
I'm in a place with single-bar wifi signal and the livestream is really choppy.
Does anyone have something like a buffered stream on a delay so I can be sure I don't miss anything, even if I have to stop to buffer more of the stream?
I have a vanilla, chrome browser, and a fairly recent VLC.
[+] [-] dandelany|13 years ago|reply
IANAPhysicist, but I'd be interested to know how strict the 5-sigma discovery rule is considered - for example, could they still get a Nobel prize for a 4.9σ announcement? I suppose it's not that big a deal - the LHC is still running, and I'm sure they'll have enough data for a true 5σ announcement soon. Regardless, hats off to all involved, it must be exciting to be at the forefront of human knowledge :)
[+] [-] jasonwatkinspdx|13 years ago|reply
The second presentation showed a 5 sigma result.
I'm Incredibly disappointed by the trivial inaccuracy of comments on hacker news lately, and that corrections never get upvoted quickly enough to prevent the spread of misinformation.
[+] [-] Almaviva|13 years ago|reply
No!! It's the chance that randomness could produce a result that large. This distinction sounds pedantic, but misunderstanding this is widespread and leads to fallacies committed frequently by very smart people who ought to know better in many fields.
[+] [-] SiVal|13 years ago|reply
[+] [-] chime|13 years ago|reply
Edit: It is worth noting that 125GeV fits well within Fermilab's recent announcement: http://news.discovery.com/space/tevatron-data-detects-higgs-...
[+] [-] ekianjo|13 years ago|reply
By the way, σ measurements are also used in many engineering jobs, and quality systems measurements. The kind of industry "goal" is to get 6σ (let's say when you manufacture consumer goods in large quantities, like millions every month). But for some other industries, 9σ is the benchmark - and from what I know, air companies have quality systems up to 9σ to ensure the lowest risk of something wrong happening.
[+] [-] lmm|13 years ago|reply
It's very much a HEP thing, and done that way because HEP is pretty much all statistical analysis these days. Other fields wouldn't treat the sigmas as the most important thing, and I've heard mutterings that it's not really the most accurate approach - but it is objective and easy to apply.
[+] [-] mkramlich|13 years ago|reply
[+] [-] haberman|13 years ago|reply
[+] [-] raphinou|13 years ago|reply
[+] [-] bobsy|13 years ago|reply
"I know a lot of people are tuning in without degree's in Physic's. Let me break it down for you in Leymens terms. We are fairly certain we have discovered this. It is important because of that. Now let me get onto why we think this."
I get that this talk is not meant for me. However, it is important - apparently. Its on the front page of Guardian.
If this is an announcement of great importance and it is 98% mumbo jumbo aimed at high end Physicists or whatever then.. I don't know. Its another chance to get people interested in science that has been missed.
Note: I am not saying the whole talk should be dumbed down. I am just saying a 2-3 minute prefix for those who do not understand a single word for the first 20 minutes of the presentation.
[+] [-] nagrom|13 years ago|reply
The properties of subatomic particles include something called 'spin' - that's a fundamental quantum mechanical property. The higgs boson is the first elementary (i.e. not made of other particles) spin-less particle that we've discovered; it's completely unlike anything that we've seen up until now.
That the model that we have constructed can accurately predict its existence and the way that it decays without having observed anything like that beforehand is a huge confirmation that we're in the right region of model space. Today seems to be a huge confirmation that out understanding of physics is not fundamentally broken.
That's why its important; the prediction is like attempting a 5-point dive and nailing it pretty much perfectly. It's an impressive confirmation of 50 years of theoretical work.
(The anarchist in me would have preferred them not to find anything, I must admit. That would have been much more interesting, as the standard model came tumbling down... :-)
[+] [-] drostie|13 years ago|reply
What I can tell you is, the parts which sound the most intimidating are actually probably the simplest bits. CERN operates a particle accelerator -- this means that the LHC basically smacks subatomic particles into each other at absurdly high speeds to create infinitesimal explosions with tremendous amounts of energy (these are the TeV, GeV numbers that you see -- they're talking about the amount of energy that was concentrated in the explosion). The explosion essentially disrupts the underlying fields of the universe so much that new particles can be created or destroyed, but if you excite the Higgs field to its quantizing particle, it tends to immediately decay into other things.
The other things are subatomic particles, including quarks (the letters u, d, c, s, t, and b for up, down, charm, strange, top and bottom -- you may have heard him for example say 'bb') and bosons (he talked a bit about W W* and gamma-gamma; gamma rays are light while W bosons are, well, a little more complicated let's say).
All of the stuff he says about Monte Carlo and so on is about creating "expected" curves from the Standard Model. You want to have two curves, "expected" vs. "actual", so that you can compare them.
On the base axis usually there is energy -- this is the energy of the explosion. There are usually two curves from Monte Carlo which tell you what you expect to see. Then there are data points with error bars which tell you what's actually seen and what the statistical "counting" errors are, how weak the signal is. Usually there is then a follow-up graph where they have tried to "subtract out the noise" to see the signal more clearly.
[+] [-] antonioevans|13 years ago|reply
[+] [-] JonnieCache|13 years ago|reply
Even if you are working at CERN running the equipment, there's no way you could absorb all the info on each of those slides in the 10 to 15 seconds she shows them. They might as well have pictures of frolicking kittens on them.
[+] [-] unknown|13 years ago|reply
[deleted]
[+] [-] noselasd|13 years ago|reply
[+] [-] short_circut|13 years ago|reply
[+] [-] guelo|13 years ago|reply
Atlas comes in at ~126.5 GeV with 5.0σ. That would be a confirmed discovery!
Interesting that Atlas' mass is outside CMS's confidence range, though Atlas didn't have a range on theirs.
[+] [-] diminish|13 years ago|reply
[+] [-] InclinedPlane|13 years ago|reply
[+] [-] gorak|13 years ago|reply
[+] [-] Maro|13 years ago|reply
Clarification:
http://public.web.cern.ch/public/en/lhc/LHCExperiments-en.ht...
[+] [-] raverbashing|13 years ago|reply
Since this is apparently "only seen" through the Monte Carlo analysis I suppose they haven't seen one specific particle decay with it, I suppose?!
[+] [-] zethraeus|13 years ago|reply
(edit: The current ATLAS talk, not the first one on the CMS data)
[+] [-] drostie|13 years ago|reply
It might be very interesting to try to use comet-casting or websockets to revolutionize chat in precisely that way, realtime threaded discussions. So, in addition to all of the chat constraints you have the ability to dynamically mark certain chat messages as replying to other messages, and as the noise in the chat room gets higher you can filter yourself to just "I want to follow this discussion."
[+] [-] ehsanu1|13 years ago|reply
[+] [-] dmvaldman|13 years ago|reply
[+] [-] exolab|13 years ago|reply
[+] [-] gouranga|13 years ago|reply
Can people please stop posting intervals in headlines i.e. "20 minutes!"
It expired a long time ago and was probably too late by the time the first people read it.
Please use at 12:00 UTC or something (a time).
[+] [-] korussian|13 years ago|reply
Didn't he practice this before? Can't he just tell us what he wants to tell us, and skip over the rest?
[+] [-] jmcqk6|13 years ago|reply
[+] [-] mkramlich|13 years ago|reply
[+] [-] robryan|13 years ago|reply
[+] [-] waterlesscloud|13 years ago|reply
[+] [-] modarts|13 years ago|reply
I'm not exactly sure how you'd expect some sort of tldr; of potentially one of the most important scientific announcements of the last 100 years.
[+] [-] tomjakubowski|13 years ago|reply
[+] [-] lancefisher|13 years ago|reply
[+] [-] dgquintas|13 years ago|reply
[+] [-] Maro|13 years ago|reply
[+] [-] obilgic|13 years ago|reply
[+] [-] chime|13 years ago|reply
[+] [-] mkramlich|13 years ago|reply
And now it has been confirmed to 5 sigma. :)
[+] [-] timcederman|13 years ago|reply
[+] [-] trafficlight|13 years ago|reply
[+] [-] lancefisher|13 years ago|reply
[+] [-] JonnieCache|13 years ago|reply
[+] [-] Sukotto|13 years ago|reply
Does anyone have something like a buffered stream on a delay so I can be sure I don't miss anything, even if I have to stop to buffer more of the stream?
I have a vanilla, chrome browser, and a fairly recent VLC.
[+] [-] humbert|13 years ago|reply
If that's choppy, save it to disk with rtmpdump: rtmpdump -v -o cern1_900.flv -r rtmp://cern.fc.llnwd.net/cern/cern1_900
edit: alternate bitrates (thanks to Brajeshwar): cern1_900 cern1_600 cern1_300
[+] [-] Indyan|13 years ago|reply