Uncommon Descent Contest Question 13: The Large Hadron Collider is back up and running, but why?

First of all, I'd like to thank Vjtorley and Nakashima for their detailed explanations. While I hold nationalism a dangerous idiology, for once I am proud to be a European taxpayer. For centuries and until recently, our continent has been ravaged by wars. To see these countries now united in a noble and peaceful effort, spending money not on war but on research, gives me hope for our future. Kontinental

Wait, wait, I got it. 248? 42? What was the question again? toscents

How much time and money Babel spent on that tower? What did it tell us that was worth that time and trouble? Sorry, that's all I got. toscents

"Nine billion dollars and 15 years later, what is the Large Hadron Collider likely to tell us that is worth the cost and trouble?" Exactly what the LHC will tell us cannot yet be known but will fall into one of two broad categories. Either that our current understanding of space, time and matter is generally correct in which case the LHC will reveal detail never seen before. Or that our current understanding is wrong, in which case we'd better work to fix that and understand what's really going on. And either of those two outcomes is valuable because every other time we have peered deeper into the structure and behaviour of matter and the universe's fundamental forces we have learned things of direct practical use. Learning that matter was composed of different sorts of "atoms" spurred chemistry and metallurgy, further assisted when experimenters learnt that those atoms were in turn made of negatively charged "electrons" and a heavier positively charged part. Figuring out that the atom's positive charge was concentrated in tiny "nuclei" vastly smaller than the atom and subsequent discoveries that the nucleus was made of both protons and neutrons spawned all nuclear technology from power generation to cancer radiotherapy, while discovering the relationship between magnetism and electricity and developing a tested theory of "electro magnetic fields" gave birth to all the electrical infrastructure we take for granted. Discovery that the smallest particles of matter behaved in different ways than matter at everyday scales led to the quantum mechanics which underpins much of modern electronics and permits the design of more communications and computing technology. Antimatter, for a long time only a speculative possibility and a staple of bad science fiction books, is now a confirmed reality being put to work every day in medical imaging and could even lead to better cancer therapies. All thanks to painstaking and often slightly slow and expensive work in the arcane world of particle physics and field theory. Go, physics! A couple of centuries ago the bystander could have read about the work of those early experimenters and asked "what is studying these hypothetical 'atoms' likely to tell us that is worth the cost and trouble?" and nobody would have been able to give a satisfactory answer. Today we know better, that we can afford it and it'll pay off. And quite apart from the likely future technologies built on whatever the LHC uncovers we will also gain a deeper insight into how the universe really works, what stuff is made of and how it behaves. This is valuable in its own intangible way because nobody likes to be ignorant. waterbear

Having been a physics graduate student in 1970 and wondering then how there could be work for all the PhD candidates lurking around, plus being blessed with a bad economy that forced me to pursue a different life course, I had to wonder what would be the fate of my fellow contemplators of the most esoteric stuff ever know to man, quantum mechanics. It was about that time that mathematical physics began to take over from the real stuff, as I recall, but then that's what happens when real physics can't provide enough dissertation topics for the glut of future professors. Reading the series of quantum speculations spewing forth over the decades, I've always come to the same conclusion, one that is only reinforced with this latest fantasy on time travel: It's that many of those proto-PhDs I knew 40 years ago, and lately their disciples, are still infecting the labs and campuses with unphysical notions, such as that once something has occurred, it can somehow un-occur, a conclusion likely based on a misinterpretation of Feynman's and others brilliant but mainly utilitarian schemes. The best way to understand this conundrum is to look beyond its compendium of imponderable mathematics and apply the horselaugh of common sense. nilglew

The Large Hadron Collider could help answer questions that we would all like to see answered, for instance: (1) Is the Standard Model of physics actually true? The model predicts the existence of a mysterious particle called the Higgs boson, which gives other particles their mass. If the LHC experiments rule out the existence of the Higgs boson, that will ignite a revolution in physics. (2) What is dark matter? It seems that only invisible dark matter can account for the movement of clusters of glaxies, including the Bullet Cluster. But what is it? If dark matter consists of Weakly Interacting Massive Particles, a.k.a. WIMPs, then the LHC might be able to detect them indirectly. (3) What is dark energy, if it indeed exists? Recent measurements showing that the universe's expansion is accelerating suggest that some kind of mysterious energy permeates the cosmos, but according to quantum physics, the vacuum of space should contain a LOT more dark energy - in fact, 10^120 times more - than we actually observe. The LHC might tell us why. (4) Are the forces of nature all manifestations of a single force? Scientists would like to think so, for aesthetic reasons, but hard evidence is still lacking. (5) Why is gravity so much weaker than the other three forces? It’s about 10^32 times weaker than the next weakest force. Why? (6) Why is there more matter than anti-matter? (7) Are there extra dimensions of space? (8) Is God a master geometer? For me, this is perhaps the most interesting question of all. Surfer Dude and physicist Garrett Lisi once said, "I think the universe is pure geometry - basically, a beautiful shape twisting and dancing over space-time. Since E8 is perhaps the most beautiful structure in mathematics, it is very satisfying that nature appears to have chosen this geometry." Of course, I would say God. Nature doesn't choose anything, but from an aesthetic standpoint, I would expect God to make the most geometrically beautiful possible universe. According to Lisi's Exceptionally Simple Theory of Everything there should be 248 particles, corresponding to the symmetries of E8. 226 are known Standard Model particles, but some of the remaining 22 particles might be detected by the LHC. If the relations between the particles making up our universe turn out to reflect the structure of E8, then the Surfer Dude's hunch will have been vindicated. vjtorley

"Nine billion dollars and 15 years later, what is the Large Hadron Collider likely to tell us that is worth the cost and trouble?" Testing fundamental particles in a controlled environment is interesting to our curiosity. What is interesting to our curiosity may be good for science. If we learn nothing from the venture itself, we WILL learn not to expend billions of dollars in persuit of questions that may not have answers. But something tells me that's not likely to happen. I think we are likely to learn something, if not some profound insight into particle physics, simply by virtue of the fact that we have created artificially, conditions that we cannot observe naturally. We know that quarks exist, yet we cannot observe them physically - only by their percieved effect can we be relatively certain that they exist. What effects will we observe through this venture that might shed light on and/or confirm some theories that have already been posited, but not yet confirmed? CannuckianYankee

Nine billion dollars and 15 years later, what is the Large Hadron Collider likely to tell us that is worth the cost and trouble? While I haven't been able to check that $9 billion cost figure, lets accept it for argument's sake. Over 15 years, that's $600 million a year. Sounds like a lot? Not really. The US alone spends $5 billion a year on chewing gum. Or to look at it another way, Europe's population is over 700 million. The LHC cost the average European less than a dollar a year to build. Is the Higgs boson, supersymmetry and the other things that the LHC is supposed to test worth a dolloar a year? Easily yes. We'd pay more than a dollar a year if this was just entertainment. Heck, those of us that watched Angels and Demons have already done exactly that. "A billion here, a billion there, pretty soon you're talking about real money." The Senator who said that was right. But as we become too familiar with budget, bailout, and healthcare costs that each have trillion dollar pricetags, we should be thankful that Big Science actually costs so little. Nakashima

The Large Hadron Collider (LHC) is the world’s largest particle accelerator. Its stated purpose is to reveal what the precious few minutes and seconds just after the Big Bang were like. So far, the machine’s twin proton beams have been accelerated to 1.18 trillion electron volts, which falls far short of the anticipated 14 trillion electron volts that scientists hope to achieve. While the machine itself collides subatomic particles such as hadrons, protons and the like, it’s the elusive so-called “God Particle” (the Higgs-Boson) that scientists eagerly want to see. Ironically, as the colliders became bigger and more expensive, the particles they revealed became smaller. Atoms were reduced to subatomic particles such as electrons, protons, and neutrons, which then were reduced to quarks, which are formed by gluons. All these infinitesimally small particles form what we know as the universe. The Higgs boson particle is responsible for mass, and scientists want to understand why particles have mass and how that mass is distributed. Detractors claim that it is theoretically possible for the LHC to produce a (small) black hole which, being a black hole, could theoretically destroy the Earth in ways Roland Emmerich never dreamed of. What the LHC doesn’t try to answer, though, is the primary question: what caused the big bang itself? Barb