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March 15, 2013 8:56 AM Subscribe
"I'm confident that it's a Higgs particle. I don't need to call it Higgs-like any more...I may need to eat my words one day, but I think that's very unlikely.""Cern scientists believe newly discovered particle is the real Higgs boson. Results of analysis at Cern in Switzerland show particle behaves precisely as expected." Previously
I love that so many countries collaborated on this for the common good, and it actually worked.
Can someone simplify how scientists were able to predict the existence and properties of this particle?
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 9:06 AM on March 15, 2013 [2 favorites]
Can someone simplify how scientists were able to predict the existence and properties of this particle?
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 9:06 AM on March 15, 2013 [2 favorites]
And I'm going to take this opportunity to go back to a previous thread and re-read some excellent comments by physicsmatt and see if my poor brain is any more malleable now.
posted by mazola at 9:09 AM on March 15, 2013 [3 favorites]
posted by mazola at 9:09 AM on March 15, 2013 [3 favorites]
If there is a Vanilla Higgs, how far away is the Neopolitan Higgs?
posted by Mezentian at 9:11 AM on March 15, 2013 [1 favorite]
posted by Mezentian at 9:11 AM on March 15, 2013 [1 favorite]
From mazola's helpful first link:
Weight loss machines.
posted by notyou at 9:12 AM on March 15, 2013 [4 favorites]
"We hate calling it the God particle but the reason it picked that up is because it goes out and touches every other particle and gives them their property, which is their mass," Trischuk said.
Still, while the Higgs boson is fundamental to the universe itself, it's unclear what impact this discovery will have on the average person, DiStefano said.
"I don’t think that anyone can guarantee what type of outcome on any time scale," he said. "This is fundamental physics so it's hard to know in advance what, if any, of the outcomes will be."
Weight loss machines.
posted by notyou at 9:12 AM on March 15, 2013 [4 favorites]
Yo physicists, timemachines or GTFO
posted by Damienmce at 9:13 AM on March 15, 2013 [13 favorites]
posted by Damienmce at 9:13 AM on March 15, 2013 [13 favorites]
I hope the legislators who killed the Texas Superconducting Super Collider (SSC) are proud. This could have been our accomplishment much earlier with a much more powerful super collider.
posted by SollosQ at 9:13 AM on March 15, 2013 [18 favorites]
posted by SollosQ at 9:13 AM on March 15, 2013 [18 favorites]
Yo physicists, timemachines or GTFO
Just so you know, I'm turning this into a bumper sticker.
posted by Fizz at 9:14 AM on March 15, 2013 [7 favorites]
Just so you know, I'm turning this into a bumper sticker.
posted by Fizz at 9:14 AM on March 15, 2013 [7 favorites]
Yo physicists, timemachines or GTFO
How do you think they GTFO?
posted by eriko at 9:16 AM on March 15, 2013 [4 favorites]
How do you think they GTFO?
posted by eriko at 9:16 AM on March 15, 2013 [4 favorites]
I'll be willing to wait around for the time machine (but I guess one shouldn't have to?) as long as I get some cool antigrav stuff to play with in the meantime.
posted by TreeRooster at 9:17 AM on March 15, 2013 [1 favorite]
posted by TreeRooster at 9:17 AM on March 15, 2013 [1 favorite]
Here's a joke for you...
After the conclusion of the conclave, Pope Francis puts on his papal regalia and prepares for the formal ceremonies, including addressing the cardinals at St. Peters. As he's heading up the stairs, the Higgs particle appears, seemingly waiting for Pope Francis to open the ornate doors. "I'm sorry, Higgs, but this service is for cardinals only," admonishes the Holy See. "But Pope Francis," Higgs replies, "without me there is no mass!"
posted by carmicha at 9:17 AM on March 15, 2013 [55 favorites]
After the conclusion of the conclave, Pope Francis puts on his papal regalia and prepares for the formal ceremonies, including addressing the cardinals at St. Peters. As he's heading up the stairs, the Higgs particle appears, seemingly waiting for Pope Francis to open the ornate doors. "I'm sorry, Higgs, but this service is for cardinals only," admonishes the Holy See. "But Pope Francis," Higgs replies, "without me there is no mass!"
posted by carmicha at 9:17 AM on March 15, 2013 [55 favorites]
"I don’t think that anyone can guarantee what type of outcome on any time scale," he said. "This is fundamental physics so it's hard to know in advance what, if any, of the outcomes will be."
Figure out a way to siphon off and convert all the mass in the universe into energy in a crackpot free-energy scheme?
posted by saulgoodman at 9:18 AM on March 15, 2013
Figure out a way to siphon off and convert all the mass in the universe into energy in a crackpot free-energy scheme?
posted by saulgoodman at 9:18 AM on March 15, 2013
I hope the legislators who killed the Texas Superconducting Super Collider (SSC) are proud. This could have been our accomplishment much earlier with a much more powerful super collider.
*sigh* Every time I think about the SSC it just makes me mad and sad. (Smad?)
posted by kmz at 9:24 AM on March 15, 2013 [4 favorites]
*sigh* Every time I think about the SSC it just makes me mad and sad. (Smad?)
posted by kmz at 9:24 AM on March 15, 2013 [4 favorites]
"But Pope Francis," Higgs replies, "without me there is no mass!"
to which I would add, it's clear that this particle was discovered not in Cern, Switzerland, but deep in the catacombs beneath the Vatican within a moat of quicksilver, watched over by seven multi-headed Swiss Guards.
posted by philip-random at 9:30 AM on March 15, 2013 [2 favorites]
to which I would add, it's clear that this particle was discovered not in Cern, Switzerland, but deep in the catacombs beneath the Vatican within a moat of quicksilver, watched over by seven multi-headed Swiss Guards.
posted by philip-random at 9:30 AM on March 15, 2013 [2 favorites]
it's unclear what impact this discovery will have on the average person
Everybody does the Boson nova?
posted by It's Raining Florence Henderson at 9:31 AM on March 15, 2013 [4 favorites]
Everybody does the Boson nova?
posted by It's Raining Florence Henderson at 9:31 AM on March 15, 2013 [4 favorites]
But seriously, for physics people out there, what should be the interaction of the Higgs field with gravity as modeled in general relativity? Is it nothing more than another way to describe mass, so that general relativity absorbs it wholesale, or does the small scale interaction lie in that mystery zone where GR and and QM disagree and we need a theory of quantum gravity?
posted by TreeRooster at 9:36 AM on March 15, 2013 [1 favorite]
posted by TreeRooster at 9:36 AM on March 15, 2013 [1 favorite]
If there is a Vanilla Higgs, how far away is the Neopolitan Higgs?
You're thinking of Newtonian naming conventions; CERN uses quantum naming conventions. So the next eight subvariants will be East, West, Widdershins, Chocolate, Avocado, Riggs, Murtaugh, and Vichyssoise.
posted by Mayor West at 9:38 AM on March 15, 2013 [29 favorites]
You're thinking of Newtonian naming conventions; CERN uses quantum naming conventions. So the next eight subvariants will be East, West, Widdershins, Chocolate, Avocado, Riggs, Murtaugh, and Vichyssoise.
posted by Mayor West at 9:38 AM on March 15, 2013 [29 favorites]
Yesterday, I had some fun reading comments in my local paper's article about the Higgs confirmation. Some gems:
" Will it lead to the harnessing of matter or prove the existence of antimatter?"
"wow what a waste"
"another brick in the Tower of Babel..."
"Imagine pressing the "turkey" button on your home replicator and pulling a freshly roasted turkey from the previously empty space after a few moments. This is the beginning of the road that an invention like that might lie on."
"Absolute absence of anything--which doesn't actually exist because there are THINGS that are in existence under Hawking and others' preconditions--isn't a vacuum."
posted by COBRA! at 9:41 AM on March 15, 2013 [4 favorites]
" Will it lead to the harnessing of matter or prove the existence of antimatter?"
"wow what a waste"
"another brick in the Tower of Babel..."
"Imagine pressing the "turkey" button on your home replicator and pulling a freshly roasted turkey from the previously empty space after a few moments. This is the beginning of the road that an invention like that might lie on."
"Absolute absence of anything--which doesn't actually exist because there are THINGS that are in existence under Hawking and others' preconditions--isn't a vacuum."
posted by COBRA! at 9:41 AM on March 15, 2013 [4 favorites]
I'm really sorry, I have a talk to write for Wednesday that sort of... isn't written yet. At all. I'm coming off one week of conference travel and about to start another one, so I'm a bit strapped for time at the moment. If I have some spare cycles later, I'll work on another description. There's a bit of irony here, in that when exciting things happen in particle physics, there's usually a conference, and that means I have actual work to do.
In the meantime, I think most of your questions, TreeRooster, are answered in some of my previous comments on the Higgs boson in the earlier threads from around July 4. If there are specific things that don't make sense, leave a comment and I'll try to come back at some point and answer them at some point.
posted by physicsmatt at 9:42 AM on March 15, 2013 [4 favorites]
In the meantime, I think most of your questions, TreeRooster, are answered in some of my previous comments on the Higgs boson in the earlier threads from around July 4. If there are specific things that don't make sense, leave a comment and I'll try to come back at some point and answer them at some point.
posted by physicsmatt at 9:42 AM on March 15, 2013 [4 favorites]
I'm not made of time.
Let's get on that next.
posted by never used baby shoes at 9:46 AM on March 15, 2013 [1 favorite]
Let's get on that next.
posted by never used baby shoes at 9:46 AM on March 15, 2013 [1 favorite]
goddamn it people, I'm not made of time
r2
posted by It's Raining Florence Henderson at 9:46 AM on March 15, 2013
r2
posted by It's Raining Florence Henderson at 9:46 AM on March 15, 2013
CERN scientists believe. . .
I wonder if they are unionized like their rivals, the con-CERN scientists.
posted by Herodios at 9:46 AM on March 15, 2013
I wonder if they are unionized like their rivals, the con-CERN scientists.
posted by Herodios at 9:46 AM on March 15, 2013
sorry, I abused the edit button. My post originally started with "goddamn it people, I'm not made of time" but I thought I was sounding too annoyed at the prospect of discussing particle physics. And I wouldn't want to give that impression.
posted by physicsmatt at 9:49 AM on March 15, 2013
posted by physicsmatt at 9:49 AM on March 15, 2013
So you admit it, then - you are made of time. I knew it!
posted by It's Raining Florence Henderson at 9:51 AM on March 15, 2013
posted by It's Raining Florence Henderson at 9:51 AM on March 15, 2013
... aaaand this is how the Higgs Boson finally proved to Metafilter that edited particles are not massless.
posted by taz at 9:55 AM on March 15, 2013 [2 favorites]
posted by taz at 9:55 AM on March 15, 2013 [2 favorites]
I heard a quick NPR comment that finding the Higgs precisely where they expected is actually rather a disappointment for many physicists. It validates the existing model very strongly, but the existing model is incomplete and/or broken somehow, and we don't understand how. They were really hoping for a clue, and this initial result doesn't really give them one.
The commenter went on to say that there might be more Higgs-type particles at higher energy levels, and they're hopeful that maybe something will peek out as they keep ramping up at the LHC.
But, as of now, this is the worst possible success. It's too perfect.
posted by Malor at 10:09 AM on March 15, 2013 [7 favorites]
The commenter went on to say that there might be more Higgs-type particles at higher energy levels, and they're hopeful that maybe something will peek out as they keep ramping up at the LHC.
But, as of now, this is the worst possible success. It's too perfect.
posted by Malor at 10:09 AM on March 15, 2013 [7 favorites]
I was about to post to say exactly that, Malor. It's a little disappointing it isn't something unexpected. I mean I certainly expected the unexpected, and finding the expected is unexpected. If you see what I mean.
posted by edd at 10:24 AM on March 15, 2013 [3 favorites]
posted by edd at 10:24 AM on March 15, 2013 [3 favorites]
But, as of now, this is the worst possible success. It's too perfect.
God's having a laugh.
posted by philip-random at 10:29 AM on March 15, 2013
finding the Higgs precisely where they expected is actually rather a disappointment for many physicists. . . . this is the worst possible success. It's too perfect.
* Surely, they meant 29,000 ft tall. If it were 29,000 ft high it would be a flying mountain.
posted by Herodios at 10:30 AM on March 15, 2013 [10 favorites]
In March 1856, The Great Trigonometric survey calculated that Mount Everest was exactly 29,000 ft high*, but the figure released publicly was 29,002 ft -- to avoid giving the impression that their precision was no better that 1,000 feet; or worse, that they had merely guessed.
* Surely, they meant 29,000 ft tall. If it were 29,000 ft high it would be a flying mountain.
posted by Herodios at 10:30 AM on March 15, 2013 [10 favorites]
Having just got through Spin, I'm hoping this is the event that makes the Hypotheticals start puttin up their cloaky things
posted by angrycat at 10:31 AM on March 15, 2013 [1 favorite]
posted by angrycat at 10:31 AM on March 15, 2013 [1 favorite]
I was about to post to say exactly that, Malor. It's a little disappointing it isn't something unexpected. I mean I certainly expected the unexpected, and finding the expected is unexpected. If you see what I mean.
Nobody expects the spin is in the Higgs, son.
posted by It's Raining Florence Henderson at 10:40 AM on March 15, 2013 [3 favorites]
Nobody expects the spin is in the Higgs, son.
posted by It's Raining Florence Henderson at 10:40 AM on March 15, 2013 [3 favorites]
Surely, they meant 29,000 ft tall. If it were 29,000 ft high it would be a flying mountain.
I think 29,000 ft high implies that it's from sea level. How tall it is would depend on what you consider the "start" of the mountain.
...particle behaves precisely as expected.
My first thought was, how often does that happen?! It's the kind of thing that, if it happened to me, I'd assume I'm missing something.
posted by VTX at 10:55 AM on March 15, 2013
I think 29,000 ft high implies that it's from sea level. How tall it is would depend on what you consider the "start" of the mountain.
...particle behaves precisely as expected.
My first thought was, how often does that happen?! It's the kind of thing that, if it happened to me, I'd assume I'm missing something.
posted by VTX at 10:55 AM on March 15, 2013
...particle behaves precisely as expected.
My first thought was, how often does that happen?!
If you're a theorist, ALWAYS.
If you're an experimentalist, NEVER.
posted by kiltedtaco at 10:57 AM on March 15, 2013 [4 favorites]
My first thought was, how often does that happen?!
If you're a theorist, ALWAYS.
If you're an experimentalist, NEVER.
posted by kiltedtaco at 10:57 AM on March 15, 2013 [4 favorites]
notyou: "From mazola's helpful first link:"We hate calling it the God particle but the reason it picked that up is because it goes out and touches every other particle and gives them their property, which is their mass," Trischuk said.."
And here I thought it was because they wanted to call it the "Goddamn Particle".
posted by symbioid at 11:47 AM on March 15, 2013 [2 favorites]
And here I thought it was because they wanted to call it the "Goddamn Particle".
posted by symbioid at 11:47 AM on March 15, 2013 [2 favorites]
> "Will it lead to the harnessing of matter ... ?"
I am very much looking forward to the harnessing of matter.
I hope it can be harnessed for peaceful purposes.
posted by kyrademon at 12:32 PM on March 15, 2013 [3 favorites]
I am very much looking forward to the harnessing of matter.
I hope it can be harnessed for peaceful purposes.
posted by kyrademon at 12:32 PM on March 15, 2013 [3 favorites]
I am very much looking forward to the harnessing of matter.
Fool! Man was not meant to harness matter! You'll destroy us all!
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 1:04 PM on March 15, 2013 [2 favorites]
Fool! Man was not meant to harness matter! You'll destroy us all!
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 1:04 PM on March 15, 2013 [2 favorites]
So if this particle is as fundamental as they say - and we're swimming in the things all the time - why was it so goddamn hard to find?
I keed, I keed. No really. It's amusing to me, a colleague was saying today that the physicists are disappointed, because they were right and there are no more particles to find. That's science for you. Imagine coming up with a groundbreaking idea about the fundamental nature of the universe, and being DISAPPOINTED when it turns out to be true.
posted by caution live frogs at 1:11 PM on March 15, 2013
I keed, I keed. No really. It's amusing to me, a colleague was saying today that the physicists are disappointed, because they were right and there are no more particles to find. That's science for you. Imagine coming up with a groundbreaking idea about the fundamental nature of the universe, and being DISAPPOINTED when it turns out to be true.
posted by caution live frogs at 1:11 PM on March 15, 2013
I don't think any physicists are strongly asserting that 'there are no more particles to find', nor is that why they're a bit let down. Rather, they're disappointed because they know the "groundbreaking idea about the fundamental nature of the Universe" (the Standard Model) is incorrect. Somewhere.
They were hoping for evidence about where, but they didn't get that; the particle was exactly where the model predicted it to be. The Standard Model remains the best explanation, but because they know it's not the whole truth, that's a slightly disappointing result.
posted by Malor at 1:26 PM on March 15, 2013
They were hoping for evidence about where, but they didn't get that; the particle was exactly where the model predicted it to be. The Standard Model remains the best explanation, but because they know it's not the whole truth, that's a slightly disappointing result.
posted by Malor at 1:26 PM on March 15, 2013
Theology vs. Physics, Round MMMMCMXCIX: Church Finds Pope, Science Finds God (Particle)
posted by homunculus at 2:32 PM on March 15, 2013 [1 favorite]
posted by homunculus at 2:32 PM on March 15, 2013 [1 favorite]
I hope the legislators who killed the Texas Superconducting Super Collider (SSC) are proud. This could have been our accomplishment much earlier with a much more powerful super collider.
The problem is that the discovery neither confirms nor denies supersymmetry. Before the advent of the "standard model" they discovered oodles of new particles, which then were whittled down by theory into the ones we know and love. Confirming the Higgs mechanism isn't all that...
I mean, while the US is building billion dollar fighter-jets and spending trillions to make the rubble bounce in Afghanistan, I couldn't exactly say we couldn't spend 10 billion on a SSC. But, all told it's not clear to me that it would have been the best use of that money.
Fun fact: general relativity has become a marginal research activity in physics because there really isn't any funding for it outside of the other white whale of experimental physics: the gravity wave. The only way to do theoretical relativity is either in mathematics or to attach yourself to some gravity wave simulation group. Actually, I'd rather throw cash at that problem, all told.
In the end, what's being decided when these big projects get funded is which Phds win the research specialization lottery and get to have a productive career in pure science. It's just a terrible way to decide on priorities in science. But, the failure to fund the SSC punctured a 40 year bubble in particle physics Phds, pushing students into astrophysics, materials science, condensed matter theory, etc... which might not turn out so badly in the end.
posted by ennui.bz at 2:57 PM on March 15, 2013
The problem is that the discovery neither confirms nor denies supersymmetry. Before the advent of the "standard model" they discovered oodles of new particles, which then were whittled down by theory into the ones we know and love. Confirming the Higgs mechanism isn't all that...
I mean, while the US is building billion dollar fighter-jets and spending trillions to make the rubble bounce in Afghanistan, I couldn't exactly say we couldn't spend 10 billion on a SSC. But, all told it's not clear to me that it would have been the best use of that money.
Fun fact: general relativity has become a marginal research activity in physics because there really isn't any funding for it outside of the other white whale of experimental physics: the gravity wave. The only way to do theoretical relativity is either in mathematics or to attach yourself to some gravity wave simulation group. Actually, I'd rather throw cash at that problem, all told.
In the end, what's being decided when these big projects get funded is which Phds win the research specialization lottery and get to have a productive career in pure science. It's just a terrible way to decide on priorities in science. But, the failure to fund the SSC punctured a 40 year bubble in particle physics Phds, pushing students into astrophysics, materials science, condensed matter theory, etc... which might not turn out so badly in the end.
posted by ennui.bz at 2:57 PM on March 15, 2013
(actually, it also pushed physics students into "financial engineering" so maybe it was a disaster after all...)
posted by ennui.bz at 3:02 PM on March 15, 2013
posted by ennui.bz at 3:02 PM on March 15, 2013
(also, the goto place for scepticism within the HEP community is the blog: Not Even Wrong...)
posted by ennui.bz at 3:05 PM on March 15, 2013
posted by ennui.bz at 3:05 PM on March 15, 2013
The ssc was a huge boondoggle, and the us did contribute a bunch of money to the LHC.
posted by empath at 3:27 PM on March 15, 2013
posted by empath at 3:27 PM on March 15, 2013
I hope the legislators who killed the Texas Superconducting Super Collider (SSC) are proud. This could have been our accomplishment much earlier with a much more powerful super collider
Why Wasn’t the Higgs Boson Discovered in the US? Neal DeGrasse Tyson explains congressional stupidity
posted by homunculus at 3:50 PM on March 15, 2013 [1 favorite]
Why Wasn’t the Higgs Boson Discovered in the US? Neal DeGrasse Tyson explains congressional stupidity
posted by homunculus at 3:50 PM on March 15, 2013 [1 favorite]
OK. packed for the conference. Talk very much not written, but time for a beer and physics explanation.
As Malor pointed out, there is the undercurrent of disappointment that is being circulated around. Let me address the reasons behind that, which of course requires a refresher on the Higgs mechanism.
So, as I wrote here and here, we knew that there existed some mechanism in the Universe that the vacuum (empty space) to have a particular set of properties. This is for two reasons:
1) the observed weak force gets transmitted through massive particles, the W^+, W^- and Z^0 gauge bosons. According to our understanding of quantum field theory, gauge bosons that carry forces must be massless, or at high enough energy, bad things happen (bad things here being probabilities that go above 100%).
2) the observed fundamental matter fields, such as the electron, muon, quarks, etc, all appear to be "chiral." This means that their left-handed components (when the spin of these fundamental particles point opposite their direction of motion) interact with the weak force differently than their right-handed components (when their spin is parallel to their direction of motion). Because of this chirality, our understanding of QFT says these particles couldn't get a mass, yet clearly, they are massive.
The solution is to postulate some field that gets a "vacuum expectation value," that is, the field interacts with itself in such a way that it is energetically favorable for the field to not have zero value (like every other fundamental field we know of), but to sit at non-zero value everywhere in the Universe.
If this field has the correct charges under the weak and electromagnetic interactions, then we can solve both problems 1) and 2) simultaneously. What is going on is that the Universe really has the forces of "hypercharge" and "SU(2)_L" (ignore the strong interaction and gravity, as neither plays a role in this process). If there existed a Higgs field charged under both of these forces AND it gained a vacuum expectation value, then the Universe undergoes a phase change. Like water freezing into ice. Once this phase change occurs, the forces of hypercharge and SU(2)_L get mixed together; the force carriers combine: two combinations become the charged W bosons, one combination becomes the Z, and the final combination turns into the massless photon. So the electromagnetic force we know is actually a mixture of these two forces; we just live in a Universe where the "unbroken" forces are hidden. You can think of it as the higgs field forming a barrier to the propagation of the Ws and Z; the photon on the other hand has the right combination to "slip past" the barrier and so propagate at the speed of light.
To get this particular effect, whatever this "higgs field" is must have a very precise charge. Not that I'm expecting you to remember, but it turns out that it needs to be a "doublet of SU(2)_L and have hypercharge -1/2." Now, in a very surprising coincidence, it turns out that all the fundamental fermions have left- and right-handed components that differ from each other by EXACTLY this combination of charges. Well, that's not quite true. Half of them differ by hypercharge -1/2, the other by hypercharge +1/2. But that's ok, we can always take the antimatter version of the field, and then we get the right charge difference. (it also turns out that the combination of a doublet and hypercharge -1/2 contains just the right mixture to make an electrically neutral state; this is the combination that the higgs vacuum expectation value exhibits, which is why we see empty space as zero charge. Of course, if it was a different combination, that would be the one we cared about, because that would be the one the important long range force would couple to).
So, the fermions that propagate along keep knocking into this field with just the right combination of charges to let a left-handed particle turn into a right-handed one. So they do. Hypercharge and SU(2)_L are violated all to hell, but who cares, we live in the "broken phase" where these charges aren't conserved. In switching from left-handed to right-handed, these particles can gain a mass (look through my previous posts for more details). The stronger the interaction between the left- and right-handed fermions and the field, the bigger the mass. We measure the strength of that interaction in terms of a "Yukawa coupling," and the more massive fermions have larger Yukawas.
Incidentally, this whole mechanism has a 1-1 correspondence with superconductivity. Inside a superconductor, Cooper pairs of electrons cause a phase change where the "background field" of the metal has non-zero electric charge. So the photon gains a mass inside a superconductor.
So yay, we've explained why the W and Z bosons are massive, and how the fundamental fermions gain mass. Also, when we get to the high energies when we'd worry about non-unitarity (greater than 100% probabilities), we start to see the Higgs field directly, and that turns out to solve that problem. So physics is saved.
The most minimal version of this theory is "THE" Higgs field. A single field with non-zero vacuum expectation value that we knew ahead of time from measurements of the W and Z interactions. That field must have a well-understood set of charges, and therefore we can predict exactly how it will interact with the W and Z bosons (otherwise it could not do it's job). However, until we see the excitation of that field, the Higgs particle itself, we didn't know whether that minimal version of physics was correct.
For example, it was possible that instead of a fundamental field, the thing that did all this crazy stuff was a composite particle, like a proton or neutron. We've never seen a fundamental spin-0 particle, so maybe they don't exist (for reasons I'll explain in a moment, that would make our lives easier). This idea is called technicolor (in analogy to the color force that causes composite protons and neutrons), and we now know that it doesn't work, in pretty much every formulation of it I'm aware of (which isn't to say there can't be a composite Higgs, but it's harder to write a viable theory now).
Also, there could be multiple Higgs fields. Most obviously, maybe the fermions that get mass from the -1/2 and +1/2 hypercharge interactions aren't seeing the same particle, but two different ones. The theory of supersymmetry (which I'll get to) for technical reasons demands that this be the case, so supersymmetry has at least 2 higgs fields (and, it turns out, this results in 5 higgs particles altogether).
What we've just accomplished is to measure the W and Z couplings of this Higgs at 125 GeV to be close enough to those demanded by the minimal theory to say with a great deal of confidence that this particular boson is the excitation of a field that has a part of play in the breaking of hypercharge and SU(2)_L down to the forces we see at low energies (electroweak symmetry breaking). We have some good evidence that this particle decays to pairs of some fermions; certainly the b quark (and maybe the tau lepton). These are the fermions with the largest Yukawa couplings (that is, the largest mass and the largest couplings to the Higgs mechanism) that the Higgs is heavy enough to decay into (it'd love to decay into the top quark, but at 125 GeV, there isn't enough energy in a Higgs boson to create one 175 GeV top, much less two). But the errors there are large enough that maybe it's not decaying with the rate we'd expect.
So, it's important to remember, we've found a Higgs. Not the Higgs, and we won't know for certain for several years. The LHC is shut down for the upgrade to the original design energy of 14 TeV (rather than the 7 and 8 TeV that it's been running at now), and while there is data that hasn't been analyzed yet, we will have to wait 2-3 years for start-up again.
Now, the doom and gloom. We knew ahead of time that we had to find something at an energy of below 2 TeV (2000 times the rest mass of a proton) or our understanding of physics as we knew it would be very wrong. We found it. It has the right interactions as far as we can tell. It even has some very rare (but easier to see) interactions to photons that we predicted, and the rate there seems to be bang-on. This is a huge accomplishment, and we are pretty proud about that.
However, fundamental spin-0 particles are funny beasts. Every particle gets "quantum loop corrections;" corrections to their mass and couplings that depend on very energetic particles that pop in and out of existence on extremely short time scales. We've measured these changes in coupling that depend on energy, so this isn't just a bookkeeping trick. Fermions, when they get loop corrections, get corrections that go logarithmically with energy.
This means that, even if the particles that were correcting the mass of an electron could be as energetic as to be at the scale where black holes would appear (the Planck mass), the electron mass would only change by 15% or so. Logarithms are powerful like that. So we don't have to worry about the mass of the electron: there's a "bare" mass, and then you get a few percent correction and that's what we measure.
Spin-0 particles get corrections that go linearly with the energy scale. So, since we measured the Higgs at 125 GeV, if there's nothing around below the Planck scale preventing arbitrary loop corrections, this means that the bare mass is cancelled against a loop correction to insanely high precision. It'd be like you and me both picked separate 32 digit numbers, subtracted them, and got 5. It's possible, but it's more likely we'd end up with another 32 digit number.
So, when we see things in Nature that have this sort of tuning, we suspect that there's a symmetry going around we didn't know about. Something at forces those two big numbers to be exactly the same, and thus cancel. This leads us to supersymmetry. The idea is that, since these loops are so dangerous, we just add another set of loops with exactly the same magnitude, but opposite sign. Poof, the two numbers cancel, and the loop correction is zero.
We do this by giving every fundamental particle a partner with opposite spin-statistics (spin-0 gets a spin-1/2, spin-1/2 gets spin-0 and spin-1 gets spin-1/2). So there's a scalar electron to cancel the electron contribution (a selectron), a scalar top (a stop), a photino for the photon, a sstrange for a strange quark, a sup for an up, a wino for a w, and we need better names.
Problem is, we don't see superpartners in Nature. So ok, we say. The symmetry must be broken, but that just means the superpartners are somewhere around the Higgs mass, give or take. So the loops don't quite cancel, but they nearly do. If they were too heavy, we'd reintroduce the fine-tuning that they're here to prevent, so they have to be around. We'll see them at the LHC.
Except we don't. We don't even see big changes in the rare decays of the Higgs that would be solidly indicative of new physics (supersymmetry isn't the only game in town, just the best known). So, what if this is the end of new physics?
Well, we know it isn't. Or, we really really really suspect it isn't. However, the problem is that I could give VERY good arguments that the Higgs must have other new physics around it. If we don't see anything, I can't make a solid argument that there will be new physics visible at 10 TeV, or 100 TeV, or 1000000 TeV. To get money for a new collider, even in the best funding environment, physicists need to be able to go to Congress (or the EU governments, or whoever), look people in the eye and and say "we will find THIS." For the LHC, THIS was the Higgs, but we hoped to find other things as a bonus. If we don't, we have no idea where to look next. There is no THIS we can build a physics case. I could not, in good conscience, go and ask for $1 billion, or $10 billion, or whatever, to build a collider I don't know will make new discoveries, and that's with my belief that it's very important to have a strong fundamental science program in America.
So the worse case scenario is that this is it. We find the Higgs, it's exactly as we predicted, and no hints or anything for where to look next. It would be maddening, because we know there just has to be more going on, but would we ever get to see it? Maybe not. That's scary for us, because we like to solve puzzles, and to live knowing there's this enormous puzzle out there, that we could figure out if we only had a little more information, and never get that hint we need? arrrgh. Thus the paranoia and pessimism.
I'm not sure we're really there yet. As was pointed out at the conference I was just at on the Higgs results, we couldn't really realistically expect to see deviations from the Standard Model Higgs at the precision we're currently measuring at. Some things were ruled out, but they tended to be the easy things to see (because, you know, you hope that the Universe will yield it's secrets easily). However, the Universe has decided to be a bit more of a bastard. We're still in the very early stages, and the numbers are frankly jumping around a lot as new data and new analyses are finished. I'm still reasonable optimistic, if for no other reason than I know dark matter exists, and so there is new physics that needs to be explained. Maybe that new physics comes in at extremely high energies too, but again, there are separate good arguments to suspect that they'll be visible at the LHC.
posted by physicsmatt at 4:21 PM on March 15, 2013 [28 favorites]
As Malor pointed out, there is the undercurrent of disappointment that is being circulated around. Let me address the reasons behind that, which of course requires a refresher on the Higgs mechanism.
So, as I wrote here and here, we knew that there existed some mechanism in the Universe that the vacuum (empty space) to have a particular set of properties. This is for two reasons:
1) the observed weak force gets transmitted through massive particles, the W^+, W^- and Z^0 gauge bosons. According to our understanding of quantum field theory, gauge bosons that carry forces must be massless, or at high enough energy, bad things happen (bad things here being probabilities that go above 100%).
2) the observed fundamental matter fields, such as the electron, muon, quarks, etc, all appear to be "chiral." This means that their left-handed components (when the spin of these fundamental particles point opposite their direction of motion) interact with the weak force differently than their right-handed components (when their spin is parallel to their direction of motion). Because of this chirality, our understanding of QFT says these particles couldn't get a mass, yet clearly, they are massive.
The solution is to postulate some field that gets a "vacuum expectation value," that is, the field interacts with itself in such a way that it is energetically favorable for the field to not have zero value (like every other fundamental field we know of), but to sit at non-zero value everywhere in the Universe.
If this field has the correct charges under the weak and electromagnetic interactions, then we can solve both problems 1) and 2) simultaneously. What is going on is that the Universe really has the forces of "hypercharge" and "SU(2)_L" (ignore the strong interaction and gravity, as neither plays a role in this process). If there existed a Higgs field charged under both of these forces AND it gained a vacuum expectation value, then the Universe undergoes a phase change. Like water freezing into ice. Once this phase change occurs, the forces of hypercharge and SU(2)_L get mixed together; the force carriers combine: two combinations become the charged W bosons, one combination becomes the Z, and the final combination turns into the massless photon. So the electromagnetic force we know is actually a mixture of these two forces; we just live in a Universe where the "unbroken" forces are hidden. You can think of it as the higgs field forming a barrier to the propagation of the Ws and Z; the photon on the other hand has the right combination to "slip past" the barrier and so propagate at the speed of light.
To get this particular effect, whatever this "higgs field" is must have a very precise charge. Not that I'm expecting you to remember, but it turns out that it needs to be a "doublet of SU(2)_L and have hypercharge -1/2." Now, in a very surprising coincidence, it turns out that all the fundamental fermions have left- and right-handed components that differ from each other by EXACTLY this combination of charges. Well, that's not quite true. Half of them differ by hypercharge -1/2, the other by hypercharge +1/2. But that's ok, we can always take the antimatter version of the field, and then we get the right charge difference. (it also turns out that the combination of a doublet and hypercharge -1/2 contains just the right mixture to make an electrically neutral state; this is the combination that the higgs vacuum expectation value exhibits, which is why we see empty space as zero charge. Of course, if it was a different combination, that would be the one we cared about, because that would be the one the important long range force would couple to).
So, the fermions that propagate along keep knocking into this field with just the right combination of charges to let a left-handed particle turn into a right-handed one. So they do. Hypercharge and SU(2)_L are violated all to hell, but who cares, we live in the "broken phase" where these charges aren't conserved. In switching from left-handed to right-handed, these particles can gain a mass (look through my previous posts for more details). The stronger the interaction between the left- and right-handed fermions and the field, the bigger the mass. We measure the strength of that interaction in terms of a "Yukawa coupling," and the more massive fermions have larger Yukawas.
Incidentally, this whole mechanism has a 1-1 correspondence with superconductivity. Inside a superconductor, Cooper pairs of electrons cause a phase change where the "background field" of the metal has non-zero electric charge. So the photon gains a mass inside a superconductor.
So yay, we've explained why the W and Z bosons are massive, and how the fundamental fermions gain mass. Also, when we get to the high energies when we'd worry about non-unitarity (greater than 100% probabilities), we start to see the Higgs field directly, and that turns out to solve that problem. So physics is saved.
The most minimal version of this theory is "THE" Higgs field. A single field with non-zero vacuum expectation value that we knew ahead of time from measurements of the W and Z interactions. That field must have a well-understood set of charges, and therefore we can predict exactly how it will interact with the W and Z bosons (otherwise it could not do it's job). However, until we see the excitation of that field, the Higgs particle itself, we didn't know whether that minimal version of physics was correct.
For example, it was possible that instead of a fundamental field, the thing that did all this crazy stuff was a composite particle, like a proton or neutron. We've never seen a fundamental spin-0 particle, so maybe they don't exist (for reasons I'll explain in a moment, that would make our lives easier). This idea is called technicolor (in analogy to the color force that causes composite protons and neutrons), and we now know that it doesn't work, in pretty much every formulation of it I'm aware of (which isn't to say there can't be a composite Higgs, but it's harder to write a viable theory now).
Also, there could be multiple Higgs fields. Most obviously, maybe the fermions that get mass from the -1/2 and +1/2 hypercharge interactions aren't seeing the same particle, but two different ones. The theory of supersymmetry (which I'll get to) for technical reasons demands that this be the case, so supersymmetry has at least 2 higgs fields (and, it turns out, this results in 5 higgs particles altogether).
What we've just accomplished is to measure the W and Z couplings of this Higgs at 125 GeV to be close enough to those demanded by the minimal theory to say with a great deal of confidence that this particular boson is the excitation of a field that has a part of play in the breaking of hypercharge and SU(2)_L down to the forces we see at low energies (electroweak symmetry breaking). We have some good evidence that this particle decays to pairs of some fermions; certainly the b quark (and maybe the tau lepton). These are the fermions with the largest Yukawa couplings (that is, the largest mass and the largest couplings to the Higgs mechanism) that the Higgs is heavy enough to decay into (it'd love to decay into the top quark, but at 125 GeV, there isn't enough energy in a Higgs boson to create one 175 GeV top, much less two). But the errors there are large enough that maybe it's not decaying with the rate we'd expect.
So, it's important to remember, we've found a Higgs. Not the Higgs, and we won't know for certain for several years. The LHC is shut down for the upgrade to the original design energy of 14 TeV (rather than the 7 and 8 TeV that it's been running at now), and while there is data that hasn't been analyzed yet, we will have to wait 2-3 years for start-up again.
Now, the doom and gloom. We knew ahead of time that we had to find something at an energy of below 2 TeV (2000 times the rest mass of a proton) or our understanding of physics as we knew it would be very wrong. We found it. It has the right interactions as far as we can tell. It even has some very rare (but easier to see) interactions to photons that we predicted, and the rate there seems to be bang-on. This is a huge accomplishment, and we are pretty proud about that.
However, fundamental spin-0 particles are funny beasts. Every particle gets "quantum loop corrections;" corrections to their mass and couplings that depend on very energetic particles that pop in and out of existence on extremely short time scales. We've measured these changes in coupling that depend on energy, so this isn't just a bookkeeping trick. Fermions, when they get loop corrections, get corrections that go logarithmically with energy.
This means that, even if the particles that were correcting the mass of an electron could be as energetic as to be at the scale where black holes would appear (the Planck mass), the electron mass would only change by 15% or so. Logarithms are powerful like that. So we don't have to worry about the mass of the electron: there's a "bare" mass, and then you get a few percent correction and that's what we measure.
Spin-0 particles get corrections that go linearly with the energy scale. So, since we measured the Higgs at 125 GeV, if there's nothing around below the Planck scale preventing arbitrary loop corrections, this means that the bare mass is cancelled against a loop correction to insanely high precision. It'd be like you and me both picked separate 32 digit numbers, subtracted them, and got 5. It's possible, but it's more likely we'd end up with another 32 digit number.
So, when we see things in Nature that have this sort of tuning, we suspect that there's a symmetry going around we didn't know about. Something at forces those two big numbers to be exactly the same, and thus cancel. This leads us to supersymmetry. The idea is that, since these loops are so dangerous, we just add another set of loops with exactly the same magnitude, but opposite sign. Poof, the two numbers cancel, and the loop correction is zero.
We do this by giving every fundamental particle a partner with opposite spin-statistics (spin-0 gets a spin-1/2, spin-1/2 gets spin-0 and spin-1 gets spin-1/2). So there's a scalar electron to cancel the electron contribution (a selectron), a scalar top (a stop), a photino for the photon, a sstrange for a strange quark, a sup for an up, a wino for a w, and we need better names.
Problem is, we don't see superpartners in Nature. So ok, we say. The symmetry must be broken, but that just means the superpartners are somewhere around the Higgs mass, give or take. So the loops don't quite cancel, but they nearly do. If they were too heavy, we'd reintroduce the fine-tuning that they're here to prevent, so they have to be around. We'll see them at the LHC.
Except we don't. We don't even see big changes in the rare decays of the Higgs that would be solidly indicative of new physics (supersymmetry isn't the only game in town, just the best known). So, what if this is the end of new physics?
Well, we know it isn't. Or, we really really really suspect it isn't. However, the problem is that I could give VERY good arguments that the Higgs must have other new physics around it. If we don't see anything, I can't make a solid argument that there will be new physics visible at 10 TeV, or 100 TeV, or 1000000 TeV. To get money for a new collider, even in the best funding environment, physicists need to be able to go to Congress (or the EU governments, or whoever), look people in the eye and and say "we will find THIS." For the LHC, THIS was the Higgs, but we hoped to find other things as a bonus. If we don't, we have no idea where to look next. There is no THIS we can build a physics case. I could not, in good conscience, go and ask for $1 billion, or $10 billion, or whatever, to build a collider I don't know will make new discoveries, and that's with my belief that it's very important to have a strong fundamental science program in America.
So the worse case scenario is that this is it. We find the Higgs, it's exactly as we predicted, and no hints or anything for where to look next. It would be maddening, because we know there just has to be more going on, but would we ever get to see it? Maybe not. That's scary for us, because we like to solve puzzles, and to live knowing there's this enormous puzzle out there, that we could figure out if we only had a little more information, and never get that hint we need? arrrgh. Thus the paranoia and pessimism.
I'm not sure we're really there yet. As was pointed out at the conference I was just at on the Higgs results, we couldn't really realistically expect to see deviations from the Standard Model Higgs at the precision we're currently measuring at. Some things were ruled out, but they tended to be the easy things to see (because, you know, you hope that the Universe will yield it's secrets easily). However, the Universe has decided to be a bit more of a bastard. We're still in the very early stages, and the numbers are frankly jumping around a lot as new data and new analyses are finished. I'm still reasonable optimistic, if for no other reason than I know dark matter exists, and so there is new physics that needs to be explained. Maybe that new physics comes in at extremely high energies too, but again, there are separate good arguments to suspect that they'll be visible at the LHC.
posted by physicsmatt at 4:21 PM on March 15, 2013 [28 favorites]
I will stray from my usual pure-science commentary for a moment.
On the topic of the SSC and the LHC and physics funding; I don't have the figures and data to make an argument that will be convincing to certain people on this website, so I'm not going to bother. Talking to the people who were there, the SSC was killed due to the end of the Cold War and some poor political maneuvering on the part of some senior physicists. American physics would be in a better place today structurally if it was built, and I think the nation would have profited from the research and innovation on many levels, but so it goes. My pride and excitement in the Higgs discovery is not diminished because it happened in Europe. (and I guess I should be thankful, given my age, I would have not yet been in physics when the Higgs was discovered had the SSC not been canceled)
I do believe it is vitally important that science continues to be done, and pure science I believe pays critical dividends not just economically, but socially. A world-class science program is like any other piece of infrastructure: once you have it, it's cheaper to maintain it while it works than rebuild it from scratch later (and at this moment, America has the greatest program of university and national lab-level science in the world). I believe it is very important for us to continue to dream big and to build big, and to give the next generation of bright minds something to aim for. Scientists and researchers (and I include non-STEM here as well) are the people who train your engineers, who devise clever solutions to esoteric problems, and find real world applications for those solutions in our somewhat single-minded efforts to solve these bizarre puzzles. But when we build big, we must build with purpose: I would never go to Congress or to the public and ask for money to build something I didn't believe would advance science, and my biggest fear is that the LHC will not give me a convincing argument for where I should look next, or where the next generation of scientifically minded women and men should look next.
Because a world without big dreams in science is not just a more boring world, it's a poorer and less innovative one.
posted by physicsmatt at 4:46 PM on March 15, 2013 [11 favorites]
On the topic of the SSC and the LHC and physics funding; I don't have the figures and data to make an argument that will be convincing to certain people on this website, so I'm not going to bother. Talking to the people who were there, the SSC was killed due to the end of the Cold War and some poor political maneuvering on the part of some senior physicists. American physics would be in a better place today structurally if it was built, and I think the nation would have profited from the research and innovation on many levels, but so it goes. My pride and excitement in the Higgs discovery is not diminished because it happened in Europe. (and I guess I should be thankful, given my age, I would have not yet been in physics when the Higgs was discovered had the SSC not been canceled)
I do believe it is vitally important that science continues to be done, and pure science I believe pays critical dividends not just economically, but socially. A world-class science program is like any other piece of infrastructure: once you have it, it's cheaper to maintain it while it works than rebuild it from scratch later (and at this moment, America has the greatest program of university and national lab-level science in the world). I believe it is very important for us to continue to dream big and to build big, and to give the next generation of bright minds something to aim for. Scientists and researchers (and I include non-STEM here as well) are the people who train your engineers, who devise clever solutions to esoteric problems, and find real world applications for those solutions in our somewhat single-minded efforts to solve these bizarre puzzles. But when we build big, we must build with purpose: I would never go to Congress or to the public and ask for money to build something I didn't believe would advance science, and my biggest fear is that the LHC will not give me a convincing argument for where I should look next, or where the next generation of scientifically minded women and men should look next.
Because a world without big dreams in science is not just a more boring world, it's a poorer and less innovative one.
posted by physicsmatt at 4:46 PM on March 15, 2013 [11 favorites]
COBRA!: "Yesterday, I had some fun reading comments in my local paper's article about the Higgs confirmation. Some gems:
"Imagine pressing the "turkey" button on your home replicator and pulling a freshly roasted turkey from the previously empty space after a few moments. This is the beginning of the road that an invention like that might lie on.""
I would settle for the FeedLeeLoo machine from The Fifth Element.
Actually just dropped in to bring this up.
posted by Samizdata at 11:29 PM on March 15, 2013
"Imagine pressing the "turkey" button on your home replicator and pulling a freshly roasted turkey from the previously empty space after a few moments. This is the beginning of the road that an invention like that might lie on.""
I would settle for the FeedLeeLoo machine from The Fifth Element.
Actually just dropped in to bring this up.
posted by Samizdata at 11:29 PM on March 15, 2013
East Manitoba Regional Junior Kabaddi Champion '94: "I am very much looking forward to the harnessing of matter.
Fool! Man was not meant to harness matter! You'll destroy us all!"
Screw that!
Yes, I AM going to play God.
Suck it.
posted by Samizdata at 11:31 PM on March 15, 2013
Fool! Man was not meant to harness matter! You'll destroy us all!"
Screw that!
Yes, I AM going to play God.
Suck it.
posted by Samizdata at 11:31 PM on March 15, 2013
Wait, let me get the straight: If it has no mass, it doesn't matter. But that's okay because there's no charge.
See, this is why you science guys can't ever explain anything to the rest of us.
posted by mule98J at 10:25 AM on March 16, 2013
See, this is why you science guys can't ever explain anything to the rest of us.
posted by mule98J at 10:25 AM on March 16, 2013
Before more precious brain processing power is wasted in "Should I say it? Naaah" circles and get this over with, I'm gonna be that guy who's not staying a philosopher: If time machines were possible at some point in the future, something would have gone wrong and we would not exist. Apologies everyone, sincerely.
posted by dnial at 11:22 AM on March 16, 2013
posted by dnial at 11:22 AM on March 16, 2013
it's unclear what impact this discovery will have on the average person
And all for just thirteen billion dollars. What a bargain.
posted by DWRoelands at 1:44 PM on March 16, 2013
And all for just thirteen billion dollars. What a bargain.
posted by DWRoelands at 1:44 PM on March 16, 2013
I'd like to add to physicsmatt's remarks:
I'm completely unable to, but I'd like to.
posted by horsewithnoname at 2:52 PM on March 16, 2013 [2 favorites]
I'm completely unable to, but I'd like to.
posted by horsewithnoname at 2:52 PM on March 16, 2013 [2 favorites]
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posted by mazola at 9:04 AM on March 15, 2013 [3 favorites]