xkcd

by **M.C.** » Wed Jul 04, 2012 10:18 am UTC

Spoiler:

http://m.theage.com.au/world/science/co ... 21hac.html

Wow. If this pans out, it's incredible.

by **Ghostbear** » Wed Jul 04, 2012 10:31 am UTC

That's pretty sweet. The article doesn't seem to cast any real doubt on the actuality of the discovery -- is this just a property of the source used, or does anybody know if this reflects the actual level of confidence that the scientists involved have in their conclusion?

Side note: as someone who is not particularly well versed in particle physics, I was really thrown off by the measurement of mass in GeV -- I had to think about that one a bit (and then double check to make sure) before it made sense to me. Also, what can we expect as ramifications for a discovery like this? I understand (or I think I do) what it means, but is there anything we expect to be possible / more possible or likely now through this kind of knowledge?

by **Hawknc** » Wed Jul 04, 2012 10:53 am UTC

Ghostbear wrote:is this just a property of the source used, or does anybody know if this reflects the actual level of confidence that the scientists involved have in their conclusion?

5-Sigma confidence, to the best of my knowledge, means a bit under one in a million chance that it's wrong. That's apparently the threshold for making an announcement about it.

by **Max™** » Wed Jul 04, 2012 12:02 pm UTC

http://www.physicsforums.com/showthread.php?t=618073

Joe Incandela wrote:the CMS Spokesperson, on CMS progress on the search for the Higgs Boson, 4 July 2012:

We've observed a new particle. We have quite strong evidence that there's something there. Its properties are still going to take us a little bit of time. But we can see that it decays to two photons, for example, which tells us it's a boson, it's a particle with integer spin. And we know its mass is roughly 100 times the mass of the proton. And this is very significant. This is the most massive such particle that exists, if we confirm all of this, which I think we will.

And this is very, very significant. It's something that may, in the end, be one of the biggest observations of any new new phenomena in our field in the last 30 or 40 years, going way back to the discovery of quarks, for example. We see very, very strong evidence of the decay to two photons, and a very very narrow peak in the distribution. We see also the evidence of the decay to two Z-particles, which are like heavy photons, in this particular theory of elementary physics. And then we've studied the number of other channels that have reported, but these are less sensitive and are therefore less conclusive at the moment. But we are very excited. I'm extremely tired at the moment, so I may not appear to be as excited as I really am, but the significance of this observation could be very very great.

It could be ultimately seen that its properties are very consistent with the Standard Model Higgs, or it could be found out that its properties don't exactly match the predictions for the Standard Model. And if that's the case, then we have something really quite profound here. It could be a gateway, if you like, to the next phase of exploring the deepest fabric of the universe, which is pretty profound when you think about it.

And the other thing I would like to say is that obviously all of this is extremely preliminary. What we've looked for is a few grains on a beach, in one sense. I did some calculations, and if you replaced every event, every collision of the beams that we've scanned or had take place in our experiment over the last two years, if you let each one of those be represented by a grain of sand, you'd have enough sand to fill an Olympic-sized swimming pool. And the number of events that we've collected that we claim represent this observation are on the order of tens, or dozens. So it's an incredibly difficult task, and it takes a lot of care and cross-checking. We're re-calibrating, and we'll have better results, even on the current data, when we release at the end of the month. But it's very exciting.

by **Tirian** » Wed Jul 04, 2012 12:12 pm UTC

I am amazed at the superposition of these news stories. It is simultaneously an amazingly historic event, another piece of evidence of a model that has been believed for thirty years that nobody doubted would be validated, and that we have to do more experiments to really know anything of value.

by **Max™** » Wed Jul 04, 2012 12:34 pm UTC

http://motls.blogspot.com/2012/07/why-1 ... .html#more
http://motls.blogspot.com/2012/07/higgs ... .html#more

Interesting paper referenced here: http://www.physicsforums.com/showthread.php?t=560031, prediction of a 126~ GeV Higgs and talk about minimal supersymmetry models.

by **Princess Marzipan** » Wed Jul 04, 2012 2:34 pm UTC

Callooh callay!

by **Diadem** » Wed Jul 04, 2012 3:06 pm UTC

This is pretty damn awesome! Yeah! Finally!

* Does a happy little physics dance *

Hawknc wrote:
Ghostbear wrote:is this just a property of the source used, or does anybody know if this reflects the actual level of confidence that the scientists involved have in their conclusion?

5-Sigma confidence, to the best of my knowledge, means a bit under one in a million chance that it's wrong. That's apparently the threshold for making an announcement about it.

Yes. 5-sigma confidence is the standard threshold in particle physics.

by **mike-l** » Wed Jul 04, 2012 3:40 pm UTC

It's more like 1 in 3.5 million assuming a normal distribution.

The other results were 4.9 sigma, which is about 1 in 2 million.

by **Zamfir** » Wed Jul 04, 2012 5:02 pm UTC

Are these odds before or after some correction for the number of events?

by **mike-l** » Wed Jul 04, 2012 5:22 pm UTC

Zamfir wrote:Are these odds before or after some correction for the number of events?

After, at least in terms of the events they looked at. It's before any other experiments though, so there's things like http://xkcd.com/882/ to consider. But this is a field where negative results are published, and I'm not aware of any negative results in this range.

by **AVIATOR** » Thu Jul 05, 2012 10:49 am UTC

At last we're getting closer to the fundamental reason why yo momma so fat.

by **Max™** » Thu Jul 05, 2012 11:33 am UTC

Yo momma so fat it took a team of 23 Astronomers 1500 hours of combined Keck and Hubble observations to determine her mass by calculating the deflection of light passing near her ass.

Yo momma so fat if she wears a belt she risks falling below her own Schwarzschild Radius.

Yo momma so fat that the time dilation from her mass makes her appear dumber than she really is.

Yo momma so fat that she has a noticeable influence on the solar system barycenter.

The solar system consists of the sun, jupiter, yo mommas ass, and some debris.

by **Princess Marzipan** » Thu Jul 05, 2012 3:10 pm UTC

I am woefully uneducated on the elementary particles, and the Higgs boson is exciting but I can't understand quite why.

I get that we have theorized the Higgs field as an explanation for mass, I get that the Higgs boson is a necessary part of that theory, but I have no found no understandable explanation for that relationship between the Higgs boson and Higgs field. Halp?

by **mike-l** » Thu Jul 05, 2012 3:14 pm UTC

IANAPP (I am not a particle physicist), but my understanding is that the Higgs Field is kind of like the air around us, or a pool of water or some other ubiquitous substance. When you perturb the air (say by clapping your hands) or water (say by throwing a stone in) you get waves. When you perturb the Higgs field, you also get waves. Those waves are the Higgs boson. This is obviously not an exact analogy, but http://xkcd.com/895/

by **SlyReaper** » Thu Jul 05, 2012 4:58 pm UTC

See, I think I understand what a boson is in the general sense. They're things like photons and gluons which are exchanged between fermions when they interact via one of the fundamental forces; photons for electromagnetic interaction, gluons for strong nuclear force, etc. But what's the fundamental force in play with Higgs? Do they get exchanged between fermions and this Higgs field? In that case, they'd have to be constantly created because they decay bloody quickly. But how are they created? They're 130 times heavier than a proton - where does the energy come from to do a thing like that? And how does the presence of this particle "give mass" to a fermion?

Actually, come to think of it, W and Z bosons also have mass. So it's not just fermions this would seem to apply to.

by **Sizik** » Thu Jul 05, 2012 5:34 pm UTC

See: viewtopic.php?f=18&t=86920

by **mike-l** » Thu Jul 05, 2012 6:01 pm UTC

It's not as clear cut as 'fermions are matter, bosons are force carriers'. It's somewhat like that for elementary particles, but anything with integer spin is a boson, eg the nucleus of a carbon-12 atom. I think that force carriers must be bosons, but not all bosons are force carriers.

by **Wnderer** » Sat Jul 07, 2012 10:07 pm UTC

Here is a fun video explaining the Higgs boson.
http://vimeo.com/41038445

by **Minerva** » Tue Jul 10, 2012 4:05 am UTC

Max™ wrote:http://motls.blogspot.com/2012/07/why-125-gev-higgs-boson-isnt-quite.html#more
http://motls.blogspot.com/2012/07/higgs ... .html#more

Interesting paper referenced here: http://www.physicsforums.com/showthread.php?t=560031, prediction of a 126~ GeV Higgs and talk about minimal supersymmetry models.

This guy does say some very interesting stuff, and he does a pretty good job of accessible everyman explanation.

But there are a few things that he does that cause me to get a little bit skeptical and suspect a slight degree of possible crackpottery:

- Everything he links to is on arXiv, and there is not one single actual peer-reviewed, accepted and published paper.

- You can "prove" nearly every speculative silly crackpot theoretical physics crackpot claim in a way that "looks and sounds sciencey" with a link to an arxiv manuscript or two.

- Calls other physicists and established good public science communicators like Lawrence Krauss liars and idiots, etc.

- Also, he uses blogspot?

by **SlyReaper** » Thu Jul 12, 2012 5:40 pm UTC

mike-l wrote:It's not as clear cut as 'fermions are matter, bosons are force carriers'. It's somewhat like that for elementary particles, but anything with integer spin is a boson, eg the nucleus of a carbon-12 atom. I think that force carriers must be bosons, but not all bosons are force carriers.

Okay I think I get it. Photons, gluons, W+, W-, Z and gravitons (if they turn out to exist) are gauge bosons which are force carriers, and the Higgs is a scalar boson which isn't a force carrier. Okay. It's still a mystery to me how it's all supposed to work. So there's this Higgs field which is a kind of all-permeating thing like The Force in Star Wars (or, heresy of heresies, like the luminiferous aether was hypothesized to be), and there's a massive particle (a stationary electron, say), and this Higgs boson sits somewhere in the middle. So I apply an electromagnetic field to the electron which causes it to accelerate, and it doesn't accelerate infinitely because it has mass, which is resistance to acceleration. So is the Higgs boson like some sort of glue that "sticks" certain objects to the Higgs field, and this resistance to being accelerated manifests as mass? I've heard the sticky melted toffee analogy before, and as oversimplifications go, at least that's visualisable.

And here's another thing that puzzles me. CERN needed ~126MeV of energy in a gigantic machine to conjure this thing up, so how does it appear in nature? If I'm using an incredibly weak electromagnetic field to accelerate my electron, where does the energy come from to create a Higgs boson and thus impede my electron's progress? It can't have "always been there" because it decays very quickly, so a new one has to come from somewhere.

Or am I just Wrong On The Internet? I'm Wrong On The Internet aren't I.

by **Sizik** » Thu Jul 12, 2012 5:51 pm UTC

The Higgs field works along the same lines as the electromagnetic field and the gravitational field. The Higgs Boson is an exicitation of that field, analagous to photons and gravitons, except that it has mass. When things interact with the field, there aren't any Higgs bosons around, just like how an electron doesn't emit photons just because it interacts with the electromagnetic field.

Disclaimer: I am not a physicist.

by **Dauric** » Thu Jul 12, 2012 5:58 pm UTC

SlyReaper wrote:And here's another thing that puzzles me. CERN needed ~126MeV of energy in a gigantic machine to conjure this thing up, so how does it appear in nature? If I'm using an incredibly weak electromagnetic field to accelerate my electron, where does the energy come from to create a Higgs boson and thus impede my electron's progress? It can't have "always been there" because it decays very quickly, so a new one has to come from somewhere.

Or am I just Wrong On The Internet? I'm Wrong On The Internet aren't I.

Assuming I understand it right (not always a good assumption...)

It's not so much "creating" it as it is "magnifying the detectable phenomenon that show that the Higgs Boson exists.

In an astoundingly terrible analogy, consider an apple in a dark room. You can use a flashlight to bounce photons off the apple and use your Mark I biological photon detectors (ie: eyeballs) to detect the photons that bounced off the apple. The flashlight does not create the apple, nor are you detecting actual parts of the apple (the light beam does not force particles of the apple itself in to your eyes), you are detecting particles (okay, okay, wave packets, I did say it's a horrible analogy) that is reacting to the apple to give you (IE your brain) clues to the existence of the apple itself.

by **SlyReaper** » Thu Jul 12, 2012 6:09 pm UTC

But the boson itself has a mass of 126GeV/c2 does it not (I said MeV in my last post by mistake)? That rest mass energy still needs to come from somewhere.

by **Dauric** » Thu Jul 12, 2012 6:48 pm UTC

SlyReaper wrote:But the boson itself has a mass of 126GeV/c2 does it not (I said MeV in my last post by mistake)? That rest mass energy still needs to come from somewhere.

Reading more my analogy is completely wrong.

One of the things I had heard on NPR shortly after the discovery was that among the theories about the Higgs Boson is that there may be multiple types of Higgs Boson particles.

Except from Talk of the Nation between the host Ira Flatow and Sean Carroll, theoretical physicist at Cal Tech and author of the forthcoming book "The Particle at the End of the Universe,":

FLATOW: Now, we always hear about the Higgs, we hear about the Higgs particle, but as we're talking, there could be different kinds of Higgs particles, correct? There may be other ones besides this basic one.

CARROLL: That's absolutely true, and that's going to be, you know, an ongoing project. This is not the end of the story. This is the beginning of 20 or 30 years of hard work ahead of us. If you believe in super-symmetry, which is a speculative theory moving forward, there's a very definite prediction you get from that theory, which is that there should be five Higgs bosons. So it could be we've only found 20 percent of the Higgs conglomerate.

FLATOW: There should be five of them. Do they do the same as this Higgs?

CARROLL: They do different things. There's one Higgs that is kind of giving mass to half the particles. Another one is giving mass to the other half, and a few are just flying around doing their own thing.

So it looks like it may be more complicated than just the energy of one particle field.

by **mike-l** » Thu Jul 12, 2012 6:52 pm UTC

In my limited understand, the Higgs boson itself isn't giving things mass. A quark with mass has mass because it interacts with the Higgs field. The Higgs boson itself has mass because it also interacts with the Higgs field. The Higgs boson is a 'wave' in the Higgs field. (Michael Spivak really needs to keep writing his physics for mathematicians books to the point where I can actually understand this stuff!)

by **Technical Ben** » Thu Jul 12, 2012 8:57 pm UTC

Sorry as this is me posting a link in 2 threads on the Hugs Bison, but this video seems to get a really complete picture for a layman.

http://youtu.be/9Uh5mTxRQcg

by **vega12** » Fri Jul 13, 2012 1:05 am UTC

SlyReaper wrote:But the boson itself has a mass of 126GeV/c2 does it not (I said MeV in my last post by mistake)? That rest mass energy still needs to come from somewhere.

In quantum field theory, "forces" and the like are mediated by particles, but usually these particles are virtual. For instance, two electrons repel each other by exchanging many many many very low energy virtual photons. Likewise, a particle has the appearance of mass due to self interaction with many many virtual Higgs bosons. The uncertainty principle permits the creating of particles that violate various conservation laws provided it is over a very short time.

As for the field vs particle distinction, I think most physicists would argue that there is no real meaningful distinction between the two. We tend to think in QFT of the field as the fundamental object. But "particles" are just excitations in this field, so in that sense they are also "field". So when someone says that "it's not the boson but the Higgs field that gives mass", they have the right idea, but are focusing too much and a meaningless distinction. You can think of the mass as being acquired through interacting with the field, or through the self-interaction with virtual particles. Both are equally valid views, so saying it's one or the other is not a fair statement.

by **Akamai** » Wed Jul 18, 2012 1:57 pm UTC

I must say, I was disappointed to see that the thread title was a little misleading. More bison hugs!

by **Max™** » Thu Jul 19, 2012 4:22 pm UTC

The Higgs explained through a cartoon:
http://www.exploratorium.edu/origins/ce ... rtoon.html

by **Diemo** » Thu Jul 19, 2012 6:48 pm UTC

Max™ wrote:The Higgs explained through a cartoon:
http://www.exploratorium.edu/origins/ce ... rtoon.html

Were you at the ESOF?

by **Max™** » Fri Jul 20, 2012 12:44 am UTC

I wish, nah, I saw that picture a while back on another site and just google image searched it and found that page.

by **mosc** » Fri Jul 20, 2012 8:05 pm UTC

My 400-level physics may be a few years out of date but you have to keep in mind a Higgs-Boson is an earlier state of matter from very shortly after the big bang. As the theory goes, the big bang created an expanding universe filled with all the matter that exists today. The early universe was incredibly dense, far denser than even the nucleus of an atom. Protons didn't exist yet, they would be crushed. The Higgs-Boson can be thought of, in some ways, as a super-dense state of matter that filled the entire universe for an incredibly short time until it expanded, they decayed, and we got closer to the forms of matter we're used to today (There are other steps along the way. You get a subatomic soup from a decaying boson. You're a long way from incredibly empty atoms with a circling electron cloud around a nucleus). Indeed, the mass of the particle (the word particle starts to become a complex term here keep in mind) well exceeds a proton and it's physical dimensions are bordering on unthinkably tiny if even physical in form. The things are far too dense to be stable for an observable period of time. They're looking for decayed boson subatomic soup more than they're looking for the particle itself. Even that fades quickly. The forces of the early universe were far different than the one we live in. We're trying to understand this incredibly brief period better because it helps us understand the mysteries of subatomic particles, wave and particle duality, unified force theory, etc.

by **Max™** » Sat Jul 21, 2012 12:44 am UTC

Uh...

The Higgs isn't a form of matter, it's an excitation of a field state which has collapsed into a lower energy state (the vacuum expectation value) which gives a broken symmetry which we observe as particle masses.

by **Thesh** » Sat Jul 21, 2012 2:48 am UTC

The higgs boson has mass, does that not make it matter?

by **Max™** » Sat Jul 21, 2012 2:53 am UTC

Matter is a terrible word to speak of when discussing particles.

Generally when you say matter you are talking about quarks (as protons/neutrons) and electrons.

W and Z bosons have mass but aren't "matter".

by **mosc** » Mon Jul 23, 2012 2:06 pm UTC

What a completely semantic comment. It's an "earlier state of matter". Maybe you would have preferred "earlier state of mass predating matter"?

by **Max™** » Mon Jul 23, 2012 3:10 pm UTC

mosc wrote:What a completely semantic comment. It's an "earlier state of matter". Maybe you would have preferred "earlier state of mass predating matter"?

No it really is not just a semantic comment.

W and Z bosons have mass, they are not what anyone would call matter, the Higgs has mass, it is not what anyone would call matter.

It is a very important distinction.

Mass is a property possessed by the particles that compose what we describe as matter, the components of hadrons and leptons mainly, baryons (protons/neutrons), and electrons. To be specific, when I say mass here I mean rest mass.

Mass is also possessed by other particles, neutrino oscillation requires a nonzero mass for neutrinos, yet you wouldn't call them matter, since billions of them are pouring through your left eye right now.

by **mosc** » Tue Jul 24, 2012 9:04 pm UTC

It is semantic because the definition of matter is very nebulous to begin with. In particle physics, I was using it to refer to any particle with mass. You're correct in pointing out that bosons don't really take up volume but they do have a physical location in space. Obviously, in explaining what a Boson is, I'm trying to give a more layman's description. It's more important that people understand that these things have a decent amount of mass and existed primarily in an extremely early and extremely dense state of the universe predating the matter we're used to observing.

The Higgs Boson is a key part of the cosmology timeline pushing as far back into the first moments of the universe as we can theorize. I wanted to add that point to the discussion. Sorry if you don't like the way I used the word matter.

by **Max™** » Tue Jul 24, 2012 11:55 pm UTC

mosc wrote:It is semantic because the definition of matter is very nebulous to begin with. In particle physics, I was using it to refer to any particle with mass. You're correct in pointing out that bosons don't really take up volume but they do have a physical location in space. Obviously, in explaining what a Boson is, I'm trying to give a more layman's description. It's more important that people understand that these things have a decent amount of mass and existed primarily in an extremely early and extremely dense state of the universe predating the matter we're used to observing.

The Higgs Boson is a key part of the cosmology timeline pushing as far back into the first moments of the universe as we can theorize. I wanted to add that point to the discussion. Sorry if you don't like the way I used the word matter.

Yeah, that's why I said using the term matter isn't helpful.

We're mostly empty space, but the various interactions between our constituent particles produce a convincing appearance of solidity, the properties which usually come to mind when the word "matter" is used are mostly nonexistent at the subatomic scale we're talking about.

As far as the densities of the early universe, there were all sorts of processes and changes taking place before the universe even got cold enough for quarks to be stable, much less the frigid conditions baryons such as ourselves require.

It is indeed fun to help others understand the nature of this vast thing we find ourselves hurtling around in, but there is almost no explanatory benefit regarding the Higgs to be gained from "it was very hot and dense when the universe was so young I can't even properly explain how short a period of time had passed yet", as opposed to explaining the relationships between symmetries and forces, and how something as simple as a clock operating if you turn it upside down is related to light and mass, and THEN you could point out the symmetries and known force carriers, with the Higgs filling in a part of the picture which everyone can relate to: having mass and dealing with little things like gravity.

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