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Cheers! How the physics of fizz contributes to human happiness
The phenomenon that makes our favourite drinks bubbly is, alarmingly, the same one that causes decompression sickness in divers. Why do we still love it?
Think of the last time you had something to celebrate. If you toasted the happy occasion, your drink was probably alcoholic – and bubbly.
Have you ever wondered why it's so enjoyable to imbibe a glass of something that sets off a series of microexplosions in your mouth?
A glass of a bubbly drink is full of physics, history and culture. We probably first encountered fizz alongside the discovery of alcohol, since both ethanol and carbon dioxide (CO2) gas are byproducts of fermentation. Drinking carbonated substances for pleasure – rather than simply staying hydrated – appears to be something only humans do.
In 17th-century France, the Benedictine monk Dom Pérignon greatly refined what we now know as Champagne. It took him many years to perfect a bottle and cork design that could withstand the high pressures that the process required. In sparkling wine, part of the fermentation takes place after the liquid has been bottled. Since the CO2 can't escape the closed container, the pressure builds inside. In turn, this results in large gas quantities being actually dissolved into the liquid, in accordance with Henry's law – a rule stating that the amount of gas that can be dissolved in a liquid is proportional to the pressure.
Among other things, Henry's law explains why divers can get decompression sickness if they rush their ascent to the surface: at great depths, the body is exposed to a high pressure and, consequently, gases are dissolved in blood and tissues in high concentrations. Then, when surfacing, the pressure returns to the ambient level, such that the gas 'exsolves' and is released to form painful, harmful bubbles in the body. The same happens when we uncork a bottle of Champagne: the pressure suddenly drops back to its atmospheric value, the liquid becomes supersaturated with carbon dioxide – et voilà, bubbles emerge!
Over time, as liquid continues releasing gas, the size of the bubbles grows, and their buoyancy increases. Once the bubbles get sufficiently big, they can't stay stuck to the microscopic crevices in the glass where they originally formed, and so they rise to the surface. Soon after, a new bubble forms and the process repeats itself. That's why you've probably observed bubble chains forming in Champagne glasses – as well as the sad tendency of fizzy drinks to go flat after a while.
Intriguingly, Gérard Liger-Belair, professor of chemical physics at the University of Reims Champagne-Ardenne in France, discovered that most of the gas lost to the atmosphere in sparkling wine doesn't escape in the form of bubbles, but from the surface of the liquid. However, this process is highly enhanced by the way that bubbles encourage the Champagne to flow in the glass. In fact, if there were no bubbles, it would take weeks for a drink to lose its carbon dioxide.
The attractive bubbly character of Champagne can be found in other drinks, too. When it comes to beer and carbonated water, the bubbles don't come from fermentation but are introduced artificially by bottling the liquid at high pressure with an excess amount of carbon dioxide. Again, when opened, the gas can't stay dissolved, so bubbles emerge. Artificial carbonation was actually discovered by the 18th-century English chemist Joseph Priestley – better known for discovering oxygen – while investigating a method to preserve drinking water on ships. Carbonated water also occurs naturally: in the southern French town of Vergèze – where Perrier, the commercial brand of mineral water, is bottled – an underground water source is exposed to carbon dioxide at high pressure, and comes up naturally fizzy.
When a carbonated beverage is rich in contaminants that stick to the surface, known as surfactants, bubbles might not burst when they reach the top but accumulate there as foam. That's what gives beer its head. In turn, this foam affects the texture, mouthfeel and flavour of the drink. From a more physical perspective, foam also insulates the drink, keeping it colder for a longer time and acting as a barrier to the escape of carbon dioxide. This effect is so important that in the Dodger Stadium in Los Angeles beer is sometimes served with a head of artificial foam. Recently, researchers have discovered another interesting effect: a foam head prevents the beer from spilling when one walks with an open glass in hand.
Despite our solid understanding of bubble formation in drinks, a question remains: just why do we like drinks with bubbles? The answer remains elusive, but some recent studies can help us understand. The interaction of carbon dioxide with certain enzymes found in saliva causes a chemical reaction that produces carbonic acid. This substance is believed to stimulate some pain receptors, similar to those activated when tasting spicy food. So it seems that the so-called 'carbonation bite' is a kind of spicy reaction – and humans (strangely) seem to like it.
The presence and size of bubbles can even affect our perception of flavour. In a recent study, researchers found that people could experience the bite of carbonic acid without bubbles, but bubbles did change how things tasted. We still don't have a clear picture of the mechanism by which bubbles influence flavour, though soft-drink manufacturers have ways of adjusting the amount of carbonation according to the sweetness and nature of the drink. Bubbles also affect the rate at which alcohol is assimilated into the body – so it's true that a bubbly drink will make you feel inebriated more quickly.
As far as we're concerned, all this offers a great excuse to talk about physics. We enjoy bubbly drinks too, of course – but personally, we celebrate adding a touch of science to a subject so that most people can relate to it. What's more, bubbly liquids have many practical applications. They're essential to some techniques for extracting oil; for explaining deadly underwater explosions known as limnic eruptions; and for understanding many other geological phenomena, such as volcanoes and geysers, whose activity is strongly influenced by the formation and growth of gas bubbles in the erupting liquid. So, the next time you celebrate and knock back a glass of bubbly, be sure to know that physics contributes to the sum of human happiness. Salud!
This article was originally published at Aeon and has been republished under Creative Commons.
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Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.
- Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
- As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
- The film is perfectly timed for a world sheltering at home during a pandemic.
Richard Feynman once asked a silly question. Two MIT students just answered it.
Here's a fun experiment to try. Go to your pantry and see if you have a box of spaghetti. If you do, take out a noodle. Grab both ends of it and bend it until it breaks in half. How many pieces did it break into? If you got two large pieces and at least one small piece you're not alone.
But science loves a good challenge<p>The mystery remained unsolved until 2005, when French scientists <a href="http://www.lmm.jussieu.fr/~audoly/" target="_blank">Basile Audoly</a> and <a href="http://www.lmm.jussieu.fr/~neukirch/" target="_blank">Sebastien Neukirch </a>won an <a href="https://www.improbable.com/ig/" target="_blank">Ig Nobel Prize</a>, an award given to scientists for real work which is of a less serious nature than the discoveries that win Nobel prizes, for finally determining why this happens. <a href="http://www.lmm.jussieu.fr/spaghetti/audoly_neukirch_fragmentation.pdf" target="_blank">Their paper describing the effect is wonderfully funny to read</a>, as it takes such a banal issue so seriously. </p><p>They demonstrated that when a rod is bent past a certain point, such as when spaghetti is snapped in half by bending it at the ends, a "snapback effect" is created. This causes energy to reverberate from the initial break to other parts of the rod, often leading to a second break elsewhere.</p><p>While this settled the issue of <em>why </em>spaghetti noodles break into three or more pieces, it didn't establish if they always had to break this way. The question of if the snapback could be regulated remained unsettled.</p>
Physicists, being themselves, immediately wanted to try and break pasta into two pieces using this info<p><a href="https://roheiss.wordpress.com/fun/" target="_blank">Ronald Heisser</a> and <a href="https://math.mit.edu/directory/profile.php?pid=1787" target="_blank">Vishal Patil</a>, two graduate students currently at Cornell and MIT respectively, read about Feynman's night of noodle snapping in class and were inspired to try and find what could be done to make sure the pasta always broke in two.</p><p><a href="http://news.mit.edu/2018/mit-mathematicians-solve-age-old-spaghetti-mystery-0813" target="_blank">By placing the noodles in a special machine</a> built for the task and recording the bending with a high-powered camera, the young scientists were able to observe in extreme detail exactly what each change in their snapping method did to the pasta. After breaking more than 500 noodles, they found the solution.</p>
The apparatus the MIT researchers built specifically for the task of snapping hundreds of spaghetti sticks.
(Courtesy of the researchers)
What possible application could this have?<p>The snapback effect is not limited to uncooked pasta noodles and can be applied to rods of all sorts. The discovery of how to cleanly break them in two could be applied to future engineering projects.</p><p>Likewise, knowing how things fragment and fail is always handy to know when you're trying to build things. Carbon Nanotubes, <a href="https://bigthink.com/ideafeed/carbon-nanotube-space-elevator" target="_self">super strong cylinders often hailed as the building material of the future</a>, are also rods which can be better understood thanks to this odd experiment.</p><p>Sometimes big discoveries can be inspired by silly questions. If it hadn't been for Richard Feynman bending noodles seventy years ago, we wouldn't know what we know now about how energy is dispersed through rods and how to control their fracturing. While not all silly questions will lead to such a significant discovery, they can all help us learn.</p>
The multifaceted cerebellum is large — it's just tightly folded.
- A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
- The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
- This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.
Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).
A neural crêpe
A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.
So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.
The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."
Study's cross-sections of a folded cerebellum
Image source: Sereno, et al.
A complicated map
Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."
That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.
It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."
This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."
Bigger and bigger
The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.
"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."
As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."
Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."
What happens if we consider welfare programs as investments?
- A recently published study suggests that some welfare programs more than pay for themselves.
- It is one of the first major reviews of welfare programs to measure so many by a single metric.
- The findings will likely inform future welfare reform and encourage debate on how to grade success.
Welfare as an investment<p>The <a href="https://scholar.harvard.edu/files/hendren/files/welfare_vnber.pdf" target="_blank">study</a>, carried out by Nathaniel Hendren and Ben Sprung-Keyser of Harvard University, reviews 133 welfare programs through a single lens. The authors measured these programs' "Marginal Value of Public Funds" (MVPF), which is defined as the ratio of the recipients' willingness to pay for a program over its cost.</p><p>A program with an MVPF of one provides precisely as much in net benefits as it costs to deliver those benefits. For an illustration, imagine a program that hands someone a dollar. If getting that dollar doesn't alter their behavior, then the MVPF of that program is one. If it discourages them from working, then the program's cost goes up, as the program causes government tax revenues to fall in addition to costing money upfront. The MVPF goes below one in this case. <br> <br> Lastly, it is possible that getting the dollar causes the recipient to further their education and get a job that pays more taxes in the future, lowering the cost of the program in the long run and raising the MVPF. The value ratio can even hit infinity when a program fully "pays for itself."</p><p> While these are only a few examples, many others exist, and they do work to show you that a high MVPF means that a program "pays for itself," a value of one indicates a program "breaks even," and a value below one shows a program costs more money than the direct cost of the benefits would suggest.</p> After determining the programs' costs using existing literature and the willingness to pay through statistical analysis, 133 programs focusing on social insurance, education and job training, tax and cash transfers, and in-kind transfers were analyzed. The results show that some programs turn a "profit" for the government, mainly when they are focused on children:
This figure shows the MVPF for a variety of polices alongside the typical age of the beneficiaries. Clearly, programs targeted at children have a higher payoff.
Nathaniel Hendren and Ben Sprung-Keyser<p>Programs like child health services and K-12 education spending have infinite MVPF values. The authors argue this is because the programs allow children to live healthier, more productive lives and earn more money, which enables them to pay more taxes later. Programs like the preschool initiatives examined don't manage to do this as well and have a lower "profit" rate despite having decent MVPF ratios.</p><p>On the other hand, things like tuition deductions for older adults don't make back the money they cost. This is likely for several reasons, not the least of which is that there is less time for the benefactor to pay the government back in taxes. Disability insurance was likewise "unprofitable," as those collecting it have a reduced need to work and pay less back in taxes. </p>