Monday, February 19, 2018

Probing the God Particle

Almost six years ago headlines throughout the world declared the discovery of the "God Particle" at CERN's Large Hadron Collider (LHC). The name "God Particle" is not used by any physicists but is the popular name in the press for the particle that physicists call the Higgs Boson or simply the Higgs, named after Peter Higgs, one of the theoretical physicists that proposed its existence in 1964. In an earlier post, I discussed the discovery of the Higgs Boson and its significance within the standard model of particles and fields. Although the discovery of the Higgs made international news, there has been a lot of hard work that has been done since that discovery was made. In experimental particle physics the discovery of something new is often the easiest part of the process and the hard part is trying to really understand what has been discovered. Much of my research life since 2012 has been dominated by further studies of the properties of the Higgs Boson.

Why do physicists spend so much time and effort studying something that has already been discovered? What is the motivation and the expected outcome? There is a complex and comprehensive mathematical model of nature that particle physicists use. This model makes detailed predictions about what we should expect to find in our experiments. One of the most exciting possibilities is to discover something in the data that does not fit the models. When that happens, and the discovery can be confirmed and verified, it means that we have found something new that we did not know before. That is the most thrilling outcome for an experimental physicist. It is always nice to confirm something that has already been predicted. But it is even more exciting to find something not predicted and then have to figure out what previously unknown secret of nature has been discovered.

As far as the Higgs Boson is concerned, our model makes many precise and testable predictions about its properties. The Higgs is created from the high energy collision of protons at the LHC. However, the Higgs is very unstable and decays to other particles after only 10-22 seconds. The Higgs can decay in many different ways including to 2 photons, or 2 Z particles, or 2 W particles, or 2 b quarks, or 2 tau leptons, or to other possibilities. The theory predicts the fraction of times that the Higgs particle should decay to each of these possibilities. For instance, we expect that the Higgs should decay to 2 W particles 21.5% of the time, and to 2 photons 2.3% of the time. The plot at the right shows the Branching Ratio, or fraction of time, that the Higgs should decay to various particle combinations as a function of its mass (which is known to be about 125 GeV on the horizontal axis). It is more challenging to precisely determine how often the Higgs decays in these various ways than to simply discover the Higgs in the first place.

Suppose that we were to find that the Higgs particle decayed to 2 W particles more often or less often than predicted. That would mean the particle that has been discovered may be a lot like the predicted standard model Higgs Boson, but is not quite what is expected. This would be an exciting discovery for it would imply that there are things about this particle, and hence about nature itself, that we do not understand. We would have to probe the properties of the Higgs, and make many other complementary measurements, to try to figure out what we don't know.

Our theoretical calculations make other predictions about the Higgs Boson including the the angles at which the decay particles should be emitted and the ways in which the Higgs particle should be produced. It takes a lot of data and a lot of hard work to make measurements of these properties that are accurate enough to determine if the discovered particle is exactly as expected or not.

So what does it mean if a particle is not "exactly as expected?" It could mean many different things.  One option occurs because in the subatomic world, objects can be composed of a "superposition" of possibilities. It would be like having a piece of fruit that might be 95% an apple and 5% a pear. This doesn't mean that the fruit is some kind of an apple-pear hybrid, but rather that 95% of the time you ate that particular fruit it would be an apple and 5% of the time it would be a pear. You might have to eat the fruit many times to find out it isn't always an apple as expected. If the fruit is only 0.01% pear and 99.99% apple then only 1 time out of 10,000 times you ate the fruit it would be a pear and not an apple. It would take a lot of fruit eating to find that very slight deviation from the fruit being always an "expected apple."

It is possible that the Higgs particle is something like 99% what we think it is but 1% different. It will take a lot of experimental investigation to find that slight deviation. But if we do find that it were 1% different (or whatever), that would be extremely exciting! That would mean that we have discovered something about nature that is totally new. Then we would have to do the hard work to determine what it is exactly that we have discovered that is new. There are other ways that the Higgs could deviate from what is predicted by the theoretical calculations. So since 2012, and continuing for at least 15 years or more, particle physicists will be probing the properties of the Higgs Boson in excruciating detail, looking for deviations from the predicted outcome. So far we have not seen any indication that the particle discovered in 2012 has any properties that deviate in any way from the predicted standard model Higgs. But my collaborators and I will keep looking to see what secrets nature has yet to reveal.

I've thought about some possible ramifications of this post that might align with the goal of this blog—to discuss the relationship between science and Christianity. Any connection might be contrived but, as a scientist, I do get to see the soul of the artist, and I do see a parallel between the cause of excitement in research and the cause of excitement (or sometimes temporary angst) in my spiritual life. As I get to know God better, the unexpected discoveries about his character and his ways are often the most meaningful, just like the unexpected discoveries in the laboratory. Just when I think I have God figured out, he reveals deeper insights into his nature and character and I, once again, have to refine my understanding of who he is. As a human, I tend to "reduce God to manageable temrs" in the words of A. W. Tozer. But when I embrace the fact that my current understanding of God is incomplete and insufficient, then the new things he reveals to me will make my relationship with him deeper and sweeter. Like initially perplexing data that leads to a new discovery, new insights into God's character can be fraught with tension and confusion. But deeper insight and knowledge of God ultimately brings increased fulfillment, peace, excitement, and satisfaction. New discoveries have a way of doing that.

The opening pictures shows the ATLAS detector at CERN being assembled. This is one of the two detectors that discovered the Higgs Boson and is currently studying it properties. The author of this blog is a member of the ATLAS collaboration.


  1. Is it accurate to say that an underlying principle of this CERN project is that the experiments are sampling results from a population that the standard model writ large states is present reality for the laws of the universe. And that CERN has created that reality in a form that permits measurement of its operations.So as in any statistical sampling it surely requires humongous numbers of experiments, tons of data, extreme care in sampling, rejection criteria and due note of sampling error and clarity as to the confidence indicated in results. But is it a cosmic truth that the universe is at least quasi-stable as to its fundamental rules of operation, when did it become so in its history. If you set up such measurements in galactic space would you theoretically achieve the same results.

    Presidential election predictions certainty suffer from the inability to sample from an unchanging voter attitude universe right up to election day.

    Funny it seems there might be a parallel to our God and his declaration that "few are they that find the narrow way". Maybe each life is a mini experiment that under free will and over billions of lives bears out that statistic for our observation of a foreknown truth.

  2. The underlying assumption of physics is that the laws of physics are the same throughout the universe. We can test that by observing the laws of physics in distant galaxies. Nuclear decay rates and atomic line spectrum, for instance, are the same wherever we look throughout the universe. So we not only "theoretically" achieve the same results, but we can test that assumption for many cases.

  3. Thank you very much Dr Strauss, I wonder perhaps if you could further explain super-positioning and entanglement in a future post?

  4. I do not understand God either, nor do I believe I ever will. Because of my experience, I'm certain most of the words we use to describe God are qualities we ascribe to Him to personalize the relationship. Such as the use of the word Him, which is an absolutely rediculous proposition to attach gender to an entity that we have no way of knowing what form it takes. Doing so then has the inevitable consequence of humans attributing human traits to Him, usually in the form of a father that teaches us leasons. Those lessons, in turn, take the form of justice or vengence or love or patience. It is necessary for me that my understanding of God get boiled down to some pretty basic truths. God either exists or does not. I know for certain something does. I call it God because it is the English word used to describe a supernatural being that created the universe and it's laws. Everyone...and I mean EVERYone agrees with the statement God cannot be understood. I am aware some people, maybe most, are just saying God's WORKS cannot be understood. Nonetheless I can make a pretty solid arguement that if God's works cannot be understood, neither can God. Everone agree's God is not human, yet they persist in attributing human characteristics to it and I include myself in "they." It just comes naturally because it makes it easier to articulate the experiences I have that I feel God in. I have come to the conclusion in the last few years, that it is a lot easier than we think to hold seemingly conflicting view points or beliefs under the same set of hairs (or lack of in my case). That being said, here's what I've come to understand about God: it can only be explained to me THROUGH those experiences that redefine my understanding of it. I need to see God through a new pair of glasses every so often because for some reason my previous understanding of God somehow grows somewhat stale. I may still hold on to the understanding or I may not, depending. But it has the tendency to lose it's effect on me. And yet the concepts that the universe uses to grow my relationship with God are usually the same story, told slightly differently, so that the novelty of it refreshes my connection with God and the world around me. This is a somewhat frequent occurance but the really impactful ones happen maybe once or twice a year IF I'm seeking out what God's will is for me. If not, I can go a long time without feeling God's role in my life, and my experience has shown me that this is always disasterous for me. I do not doubt God anymore. I try to avoid "reducing God to managable terms" but it is extremely difficult. Even knowing what I know I still do it!! I've come to peace with this reality though. I think most of my life has been a struggle with reconciling those two conflicting truths but I have stopped fighting it. God is not a man or a teacher or a father, but He teaches me lessons and loves me unconditionally and cares about how I set about trying to set aside my will for His. I can only pray that my understanding of God continues to evolve and grow and deepen because it's the only way I seem to be able to keep that God sized hole full and appreciate life to the fullest, even during the most painful periods of it. Would you agree with this somewhat? How do you reconcile these conflicting facts? That God can be one thing and another at the same time...'super-positioning' as you related it.

  5. Great discussion, Neal. The Bible uses anthropomorphisms when referring to God. It uses the masculine pronouns and calls him Father. Of course, God is a spirit and doesn't have a gender but these descriptions help us understand a God who is not fully comprehensible. I think the reason we use human characteristics to describe God is because that is what the Bible does even though the biblical writers know that God cannot be contained nor does he literally have those characteristics.

    The way we know God is through his revelation in nature, in the Bible, and in the person of Jesus. These revelations give us insight into God in language we can understand, even knowing full well that nature and the Bible are incomplete revelations of God. I do agree that a relationship with God brings ultimately fulfillment in life and that relationship comes through Jesus and matures as we read and study God's letter to us, the Bible.

    I reconcile the various aspects of God's character by the fact that he is transcendent and incomprehensible. I'm content with living with an incomplete understanding of God, while at the same time, striving to know and understand him more.