By JOHN HEILPRIN and SETH BORENSTEIN
Associated Press
GENEVA (AP) — Scientists believe the “God particle” that might explain the underpinnings of the universe is real, and they are about to present their evidence to the world.
Physicists at the world’s biggest atom smasher plan to announce Wednesday that they have nearly confirmed the primary plank of a theory that could shape the scientific understanding of all matter.
The idea is much like gravity and Isaac Newton’s discovery: It was there all the time before Newton explained it. But now scientists know what it is and can put that knowledge to further use.
The focus of the excitement is the Higgs boson, a subatomic particle that, if confirmed, could help explain why matter has mass, which combines with gravity to give an object weight.
…
But two independent teams of physicists are cautious after decades of work and billions of dollars spent. They don’t plan to use the word “discovery.” They say they will come as close as possible to a “eureka” announcement without uttering a pronouncement as if from the scientific mountaintop.
full AP story here
Lobos Motl has more here and writes:
According to an incognito ATLAS member who spoke to Nature, they have a discovery without any doubts. Pure elation that will culminate on Wednesday morning.
A live webcast will be provided, though I expect it it will be so overloaded as to be useless:
Watch at webcast.cern.ch
Amazing? The science is way above my understanding, so if they were absolutely confusing the masses with the description of a ‘God particle’ I wouldn’t know if they were just spinning a lie, to support their own existence, let alone God. I’m sure there are scientists on this blog that can explain their hypothesis to lay people. And what would be the significance of their discovery? If it shapes up to have credible scientific facts and data?. I remember a Ph.D student giving a lecture re archaeological finds, and he said from the outset, we haven’t compiled our data yet. The answer was ‘then without the data how can you form a hypothesis’. Speculation?
Hi 🙂
I’ll try to clear up some concerns raised here:
The work is submitted to peer review. This sort of announcement is normally made prior to publication, but not prior to peer review of the analysis. If they announced the detection and then the formal paper failed peer review or none was released, the CERN physicists colleagues might eviscerate them. The only concern is that ATLAS and CERN are the only two experiments in the world capable of verifying each other’s results, and they are both at CERN. This is due to the practical constraint of there not being another very expensive LHC.
Here is how the Higgs Boson works and how its identity can be confirmed:
First, a little background is in order here: Under quantum mechanics, objects can be described both as particles and waves. Usually we think of them in terms of waves because the wave-form corresponds to a known energy and energy is conserved, so when dealing with a system over time, it makes sense to consider the wave-form, which is often given as a probability-distribution of the object’s location. (The location cannot be known exactly as the energy is a function of the wave-form, and a wave is spread over a region rather than at a single location. This is Heisenberg’s Uncertainty Principle.) When studying interactions, however, we know the relative position of the particles in question (they are in the same spot) and time of interaction, not the momentum or energy, so with this reduction in the degrees of freedom in position-space, we operate in position-space. The likelihood of interaction between two particles under specific conditions is measurable and constant, and that likelihood of interaction depends upon the types of particles in question and the relative position. Therefore position-space is equivalent to particle-type space. The framework for dealing with this is called Quantum Field Theory (QFT).
To work in QFT, we need to reinterpret the meaning of the Lagrangian equation. As we are now working with a position, we deal with Lagrangian densities, the energy at a location rather than the energy of a particle. A known quantity of energy puts the point in a single energy-state which, when considered in the parameters of position-space, is a superposition of all possible position-states. In a vacuum, we are not dealing with states where a single interaction-state and a single energy dominate, so while the masses of particle-types affect their weight in the superposition, it does not eliminate which would normally demand more energy than is available to exist (due to high masses). As a particle floats along, it passes through this vacuum populated with “virtual particles”, so it is constantly in a state with a superposition of all possible interactions occurring, each having different likelihoods. (This is a weird, but it’s quantum physics so if it weren’t, something would be wrong.) These interactions are each associated with some spectrum of possible energies of interaction (energy with which particles bounce off these virtual particles). The average energies of interactions, multiplied by their likelihood of interaction, give amounts of energy which depends on the particles present. For example, there are virtual photons near a charged particle, so bringing particle with the same charge near it will lead to a high likelihood of bouncing off those virtual photons while bringing an opposite-charged one would get it sucked in. That is the Coulomb potential. These “amounts of energy” are the terms of a Lagrangian.
Just one more level of complexity, and then things simplify: A particle’s “anti-particle” coming into a location considered in QFT, is the same as the original particle leaving it. A negative charge leaving an interaction is like a positive charge entering. All of the conserved quantities (except energy) change in exactly the same way. Now, finally, to simplify: If you just have one particle floating around, its conserved quantities (charge, spin-angular momentum, energy) will not change so any interaction, or set of interactions, which lead to such a change will have a 0 probability. However, even in a vacuum, you still have a mass-term which corresponds to the particle entering the space, having some energy, and then leaving unchanged. In QFT, having some energy means undergoing a series of interactions where, in total, conserved quantities are conserved. The way the math works out (no, I am not putting a whole math-class into this comment), the more kinetic energy (energy in excess of its mass) a particle brings into a space, the higher the likelihood of converting it into virtual particles and then having them rejoin back into the original. This changes the mass-term as energy increases (this is “renormalization”, not relativity). However, in the 0-momentum limit, this has no effect so a particle sitting roughly still should have no mass unless there is an interaction which does not demand that it split and rejoin, and changes no conserved quantities.
To get that interaction, you would need a possible particle which carries no charge and no spin. This is the Higgs Boson, the particle with which interaction has an associated energy, but no change to conserved quantities, and which has a non-zero associated probability of interaction everywhere. It is normally forbidden from forming in any lasting way because energy is conserved and there isn’t enough concentrated to create this thing, but if you put enough energy together, you can get one.
Now how do you confirm it? When you have just enough energy in a collision to produce a particle, the likelihood of its production jumps a lot. Remember that for elementary particles in vacuum, all of the usual methods of energy-dissipation in collision don’t apply. They only have momentum, no temperature, and no internal structure to crunch. They can only create new particles with that energy, so they do. If the particle is unstable (as nearly all are), it then breaks down. If you spot a spike in interactions of particles with total conserved quantities of 0 at some energy, and all particles going in and coming out appear to be interacting in exactly the same spot (one particle with quantities of 0 rather than a particle and its anti-particle), then you are looking at Higgs Boson-formation.
@Mark Luedtke
It is the tradition in this field to make an announcement when an experiment feels it has achieved an interesting result which will survive peer review. Furthermore, this is a field which traditionally wins Nobel prizes. Finally, the internal peer review on these experiments is usually far more rigorous than anything a journal can ever provide. Its difficult to describe this as pseudoscience :).
Pseudoscience can be characterised.as assertions not backed up by evidence-based reasoning, which brings us to your “prediction” of this all being a farce. What is your evidence for this ?
I can “predict” that the sun won’t shine tomorrow but unless I have a good reason for this it will be a pretty worthless statement.
@Bushbunny
One of the major open questions in modern physics is understanding the fundamental forces in the universe and the properties of the fundamental particles.
Starting back at the beginning of the last century, quantum mechanics was developed, a theory which has never been falsified despite 1000’s of attempts to the contrary. However, quantum mechanics described certain features of atoms but said little about how the forces operate.or the properties of the particles. Quantum field theory was the next development here. The so-called Standard Model is a quantum field theory which predicts the interactions of 3 of the fundamental forces. Like quantum mechanics it has never been falsified (although we’d love to be able to do this). There is one “missing link” in the Standard Model, the Higgs boson. The Higgs boson is a consequence of a part of the Standard Model theory which unifies two of the forces (the weak and electromagnetic force) and also explains why particles have masses. Finding the Higgs would provide experimental confirmation as to why the fundamental particles have masses as well as confirming the correctness of probably the most ambitious theory of nature in history..
One thing to emphasise is that the theories I’ve mentioned (quantum mechanics, Standard Model) are falsifiable. They make predictions up to just about arbitrary accuracy (up to the machine accuracy of a given computer program making a calculation or the accuracy of algorithms which solve the quantum equations).. Any deviation,, even 1 part per billionm, would be enough to falsify them and signal new physics. The experiments are highly accurate and have so far not falsified them. One on hand this is all a real success of modern science. On the other hand, we need to break a theory to go further. .
Tilo
The Dirac equation is an incorporation of special relativity into quantum physics.
The challenge is somehow getting gravity (general relativity) in a quantum picture. For various reasons (theoretical + weakness of gravity i.e. no observed quantum gravity effects which could guide us) this is very difficult.
Leif Svalgaard
You write that this all “doesn’t cut it in [your] book”. Can you point out what the experiments should have done here. An update is scheduled and the results represent a huge amount of progress in the investigation of a major open question in modern physics (the origin of mass). Do you think we should cancel the planned update ?
There is a lot of interest (justifiable in my opinion) and the results are interesting. The threshold for discovery (5 sigma) is arbitrary though something we’ll stick to since we decided this in advance. That said, there is now a wealth of strong evidence that the Higgs has been found. Are we to keep quiet about this ?
bottom line….god started infinity, so what?
Roger says:
July 3, 2012 at 10:01 pm
It’s an excellent point that you make. One of our core assumptions within the standard model is most likely false – and at the moment – no one can see it.
A noble prize and fame on the level of Newton and Einstein to the scientist who discovers the next paradigm.
Stephen Richards
This is how science is done. We make updates according to our fixed deadlines. All experiments do it. It allows the field to compare overall progress in a coherent way.
You write ” the worst possible reason to make an announcement of a non-discovery.”. I’m afraid you really don’t know what you’re talking about. The “non-discovery” is the reporting of the news of an extremely strong signal for the Higgs boson for the first time in history (after 40 years of searching). The “5 sigma” rule is arbitrary but we stick to it for ethical reasons i.e. don’t change the criteria. However, this does not effect the strength of the results. There is absolutely no reason to believe that a signal at 4.9 sigma is much more likely to be spurious than one at 5 sigma.
Perhaps you ought to acquaint yourself with some detail before commenting on a topic.
follow all the rules, but if you don’t get the catch on the scales…DQ means no trophy, no prizes…only belief of winning catch…faith!
That’s that.. Five sigmas in various channels and the CERN DG declaring we’ve got it. I was amazed by the cheering. This was a great moment in science.
Stephen says:
July 3, 2012 at 9:45 pm
Thanks for all of that. It is very informative, and fills in much of my lack of understanding of the subject. It is amazingly clear for such a complex topic.
Roger
Thank you for your many informative comments. As a non-scientist I enjoy trying to get a glimmer of a hint of what such research and discovery is all about, even if I can’t follow the serious details.
I do think that the sometimes harsh (and unfounded) remarks here about particle physicists etc. are in reaction to certain bad practices in climate science — it’s an indication that ALL good scientists across all other fields and specialties have a strong interest in seeing climatology cleaned up and straightened out. To so many of us “science” and “scientists” are broad brush strokes (of course there are many here with far more knowledge and experience than I have), and so bad actors in any field of science contributes to this unfortunate atmosphere.
Anyway, a hearty congratulations on such a major milestone in recent physics research!
Higgs particles are often found under beds.
We call them “dust bunnies” 🙂
Oops:
I made a big typo in my big comment above. I meant to say that only ATLAS and CMS could hope to detect it and verify each other’s findings. CERN is the overall institute which runs the LHC, not a particular experiment.
Stephen,
And thanks to you also for your exceptionally informative explanations. Very much appreciated by me and I’m sure many others.
p.s. I caught your typo on first quick read, which made me feel like a well-informed layperson, ha ha. But then I have physicist friends who have been talking about CERN forever, it seems like….
Thanks Roger for that.
The God-particle was an idea by gnostic quasi-Hindu sophists eight thousand years ago. They took difficult wisdom and decided it would be easier to think of it as a substance of some sort, easier to respect a thingy. They transferred the religious word meaning to that of a scientistic one: the word is still in use — prakriti. (God-particle).