Archives For standard model

hello monster

Oh for crying out loud, I’m gone for a Murphy’s Law kind of week and as soon as I can get back to blogging, the universe is supposed to explode. Well at least it’s all uphill from here. I mean if the end of the universe in a random fiery explosion of quantum fluctuations isn’t the worst thing that could happen to us, what is? You can blame the Higgs boson for all this because due to its effects on matter as we know it, we can extend the known laws of the Standard Model one way and end up with a universe that’s more or less stable as it is today, but could easily be brought down to a lower energy level, which is a theoretical physicists’ euphemism for "cataclysmic blast violent enough to change the fabric of existence." All that’s needed is a little quantum vacuum and next thing you know, fireballs will engulf the entire cosmos at the speed of light.

Or at least that’s one way to read that data which makes for an exciting headline from what’s an otherwise very specialized conference where scientists throw around big ideas just to see if any seem to catch the mass media’s interest. You see, we just found out that matter is stable over a very, very long period of time, and we’re also pretty sure that tiny quantum instabilities happen pretty much all the time, forming virtual particle/anti-particle pairs, so little quantum vacuums in the depths of space shouldn’t force matter across the cosmos to start radiating energy. And on top of that, as noted by Joseph Lykken, the originator of the hypothesis, if the tiniest change to our current models has to be made after the LHC performs its next round of experiments in the next three years, the entire notion of a universe on the brink of disaster from a quantum vacuum has to go out the window. Suddenly, doomsday doesn’t seem so imminent, huh?

Basically this idea is like forecasting that humans will be exterminated by an alien horde one of these days. It’s not entirely unthinkable and it could happen, but the odds aren’t exactly high in favor of this event and we have very little reliable data to be used to make this prediction with any sort of concrete authority. Sure, the Standard Model is incredibly well tested and underpins much of what we know to be true about matter, but when it comes to its predictive powers for all things cosmic, it’s not exactly a crystal ball, more of a murky lake with odd shapes twitching and slithering underneath. So why would Lykken make such a claim? Remember the media interest part about the purpose of the meeting where the idea was aired? There you go. Now the media is abuzz with doomsday fever and people are talking about quantum physics on the web, exactly what the meeting’s organizers were hoping would happen.

Again, this could all be true, but if we consider that the claim was made for the press and laden with enough caveats to make it more or less a wild guesstimate based on a hunch rather than a peer reviewed body of work on entropy with an attempt at the Grand Unification Theory, I’d say that it’s a pretty safe bet of be very skeptical of this one. Though it’s rather hard not to concede that "instantaneous death by quantum collapse of the cosmos" would be a pretty badass cause of death on your official paperwork because you could well claim that when you went down, you took the entire damn universe with you in a fiery explosion. Just a thought…

Share

particle decay at the lhc

Once upon a time, we looked at an explanation for dark matter involving a theory about how all matter around us could decay over 6.6 × 10^33 years and noted that there’s a controversy as to whether protons actually decay. To help settle this, astronomers took advantage of the fact that telescopes are relativistic time machines, and peered through them at a galaxy known as PKS 1830-211 — a name only a scientist could love — that just so happens to be a gravitational lens allowing us to see some 7 billion years back. To be a bit more precise, it lets us look at clouds of alcohol molecules formed eons ago in deep space and compare their spectrum to that of booze analyzed in a lab right here on Earth. Don’t worry, no hard liquor was harmed in the process as the alcohol in question is methanol, the kind used in fuel and manufacturing, and which causes blindness if ingested, not the ethanol in which we can indulge. But even if no buzz was killed for the sake of science, what exactly does looking at the light spectra of alcohol tell us about how our universe formed and its possible fate many quadrillions of years from now?

Well, the spectrum of a molecule depends on μ, the ratio of proton to hydrogen mass. That’s an extremely important metric because it lets us measure the strong force, one of the fundamental interactions of matter as we know it responsible for building atomic nuclei. Because the masses involved are created by interactions of elementary particles representing the strong force, if μ falls below or exceeds 1,836.15267245(75) and the difference is reproducibly recorded, we can say that something changed the effect of this fundamental force on matter. Hence, if the 7 billion year old methanol emits an appreciably different spectrum from methanol we create today, this would mean that one of the fundamental forces has changed as the universe grew and matter is decaying on cosmic time scales. Lucky for us, turns out that atoms are very much stable since the spectrum of methanol was for all intents and purposes identical over 7 billion years, which is just over half of the way back to the Big Bang itself.

This tells us a couple of things about the fate of the universe. First is that the Standard Model of physics is still accurate and can make viable predictions about atomic structure and decay. The second is that matter will continue to be matter at the end of the universe or decays so slowly it would only matter on time scales far exceeding the lifetimes of supermassive black holes. Finally, it allows us to rule out overly exotic explanations for the origins of dark matter involving decay of particular subatomic elements or quirky behavior of the strong force since these results match a number of previous experiments designed to find out the same thing. In a universe flying apart, churning with explosions, collisions, and radiation, it’s nice to know that you can rely on matter that makes you and the planet on which you live isn’t also slowly decaying on you like a ticking cosmic time bomb. And while space may be out to get you through GRBs, asteroids, and huge galactic train wrecks, it will at least spare the very fabric of your existence.

See: Bagdonaite, et. al. (2012). A stringent limit on a drifting proton-to-electron mass ratio from alcohol in the early universe Science DOI: 10.1126/science.1224898

Share

cern_detector_600

Apologies for the long silence but it looks like life and work has been interfering with the blogging. Oh well, all yours truly can do is grin and bear it, and take a moment when he can to write a post. Luckily for me, there’s a really big event that makes for excellent post fodder; the apparent discovery of the Higgs boson, the linchpin of mass for all known matter in the universe. The short version of all the press releases boils down to a bump in particle decay data showing a very heavy particle fitting right in the predicted range of masses and lifespan for the long-sought Higgs, a bump which hasn’t just been detected at the LHC, but replicated by the Tevatron with a lesser but still significant degree of certainty, indicating that this time, we’re really on to something huge and really heavy. Yes, pun intended. Of course not having a Higgs lurking in the data would make things exciting, but with it finally making a brief appearance means that the Standard Model of particle physics is as airtight as it could possibly be from a scientific standpoint and we can now proceed to study the boson in more depth.

So what can we find out when we study this boson? Well, by lucky coincidence, Just as we’re figuring out that our ides of how the universe works are along the right path, astrophysicists found a filament of dark matter shaping galaxy nodes and a thorough knowledge of the Higgs could provide us with clues about the ultimate makeup and fate of the cosmos. We may also study how the Higgs affects quantum particles to answer a few of our pressing questions about quantum mechanics. Practical applications like creating a relativistic rocket by canceling out the Higgs boson’s effects on matter with a finely calibrated device, allowing our spacecraft to cross the vast distances between stars within years rather than eons, are probably too far fetched at this point to consider seriously. However, who knows what we could accomplish when we understand the origins of all mass? That’s the fun of science and technology. You never know what you can discover or create until you set your mind to it and try. The current confirmation of the Higgs shows us how far particle physics has come in a century; from barely being able to define atoms, it can now define and model entire particle zoos.

And which physics keeps studying the Higgs, I hope that the media will quickly forget the bosons’ unfortunate nickname since calling it The God Particle misrepresents Leon Lederman’s original intention to convey how hard it was to find the boson despite its perfect fit into every other experiment and equation, and by letting his publisher change his phrase “the goddamned particle” into a pseudo-religious euphemism he earned a lot of cold stares from his fellow scientists. Yes, it is a critically important particle and yes, it has very profound effects on matter as we know it, but it has nothing to do with theology or a deity, and ultimately, all the particles defined by the Standard Model are important because they all play a role in the makeup of our universe. To go out of your way to pin the responsibility for making the cosmos as it is on a single particle and endow it with a highly misleading supernatural epithet just because it resonates with the faithful, it just plain wrong. We need to name it in a way that gives credit to Peter Higgs’ lifetime of work since it was his labor that made the LHC’s discovery possible and enabled us to keep extending the Standard Model to the dawn of the cosmos itself.

Share