How the Big Rip could end the world
16 December, 2018
Pixabay
- A cosmological model predicts that the expanding Universe could rip itself apart.
- Too much dark energy could overwhelm the forces holding matter together.
- The disaster could happen in about 22 billion years.
Perhaps it's not the most cheerful thought, but people have preoccupied themselves with how the world around them could end for millennia. Now in the scientific age, one such dire prediction comes from math and physics. The theory of the Big Rip says that at some point in the distant future, the universe could rip itself apart, with everything in existence from animals to atoms becoming shredded.
''In some ways it sounds more like science fiction than fact,'' said physicist Dr. Robert Caldwell of Dartmouth, who first proposed this dramatic idea in a 2003 paper he wrote with Dr. Marc Kamionkowski and Dr. Nevin Weinberg from the California Institute of Technology.
The cosmological model of the Big Rip is predicated on the notion that if the universe continues to accelerate in its expansion, it will eventually reach the point where all the forces that hold it together would be overcome by dark energy. Dark energy is the rather mysterious force that is predicted to make up 68% of the energy of the observable universe. If it overwhelms gravitational, electromagnetic and weak nuclear forces, the universe would literally come apart.
A new model of the Big Rip theory published in 2015 actually came up with the date when the Universe would meet its demise - about 22 billion years from now. The 2015 model was developed by professor Marcelo Disconzi of Vanderbilt University in collaboration with physics professors Thomas Kephart and Robert Scherrer.
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The timeline of how life universe ends up in a Big Rip.
Credit: Jeremy Teaford, Vanderbilt University
Disconzi's hypothesis says that a Big Rip can occur when dark energy will become stronger than gravity, reaching a point when it can rip apart single atoms. The professor's model shows that as its expansion becomes infinite, the viscosity of the universe will be responsible for its destruction. Cosmological viscosity measures how sticky or resistant the universe is to expanding or contracting.
If the Big Rip theory is correct, one day we could reach a moment when planets and everything on them will be torn apart. Then the atomic and molecular forces will be ripped open, electrons splitting from atoms, all the way down to the quarks and anything smaller. But until then, check out his video for more on the Big Rip:
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Surprising Science
<p>You know the drill. You're having dinner when suddenly a black nose appears under the table between your legs. You tilt back and there are those eyes. Those eyes. If you're a savvy dog owner, you resist sliding down there — eating from the table is a bad habit you don't want to encourage. Plus, this is your food. It's people food. We don't eat <em>animal</em> food. Dogs have their own food, specially formulated for their dietary needs. Right?</p><p>Well, maybe not. A new study from researchers at the University of Illinois (U of I) finds that not only is human-grade food digestible for dogs, but it's actually more digestible than much dog food. The proof is in the pooing.</p><p>The study is an accepted manuscript for the peer-reviewed <a href="https://academic.oup.com/jas/advance-article-abstract/doi/10.1093/jas/skab028/6123189?redirectedFrom=fulltext" target="_blank">Oxford Academic Journal of Animal Science</a>.</p>
Four diets were tested
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NjY0NjIxMn0._w0k-qFOC86AqmtPHJBK_i-9F5oVyVYsYtUrdvfUxWQ/img.jpg?width=980" id="1b1e4" class="rm-shortcode" data-rm-shortcode-id="87937436a81c700a8ab3b1d763354843" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
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<p>The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The <a href="https://frontierpets.com.au/blogs/news/how-kibble-or-dry-dog-food-is-made" target="_blank">ingredients</a> of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a <a href="https://en.wikipedia.org/wiki/Food_extrusion" target="_blank">pasta maker</a>. The resulting pellets are sprayed with additional flavor and color.</p><p>For four weeks, researchers fed 12 beagles one of four diets:</p><ol><li>a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe</li><li>a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe</li><li>a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe</li><li>another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.</li></ol><p>The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts. </p><p>(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)</p><p>Senior author <a href="https://ansc.illinois.edu/directory/ksswanso" target="_blank" rel="noopener noreferrer">Kelly S. Swanson</a> of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he <a href="https://aces.illinois.edu/news/feed-fido-fresh-human-grade-dog-food-scoop-less-poop" target="_blank">says</a>, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."</p>
Tracking the effect of each diet
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NjY1NTgyOX0.AdyMb8OEcjCD6iWYnXjToDmcnjfTSn-0-dfG96SIpUA/img.jpg?width=980" id="da892" class="rm-shortcode" data-rm-shortcode-id="880d952420679aeccd1eaf32b5339810" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
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<p>The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.</p><p>It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.</p><p>Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."</p><p>Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.</p><p>"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in <a href="https://academic.oup.com/jas/article/92/9/3781/4702209#110855647" target="_blank">previous studies</a>, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."</p>
How did kibble take over canine diets?
<p>Historically, dogs ate scraps left over by humans. It has only been <a href="https://www.thefarmersdog.com/digest/the-history-of-commercial-pet-food-a-great-american-marketing-story/" target="_blank">since 1870</a>, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn <a href="https://www.dogfoodadvisor.com/choosing-dog-food/animal-by-products/" target="_blank">human-food waste</a> into profit.</p><p>Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are <a href="https://www.nytimes.com/2014/08/03/magazine/who-made-that-dog-biscuit.html" target="_blank">overweight or obese</a>, and certainly their diet is a factor.<span></span></p><p>We're not so special among animals after all. If something's healthy for us to eat—we're <em>not</em> looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.</p>
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Surprising Science
<p> Our <a href="https://www.cell.com/ajhg/fulltext/S0002-9297(21)00013-6" target="_blank">new research</a> shows that a common genetic variant in the skeletal muscle gene, ACTN3, makes people more resilient to cold temperatures.</p><p>Around one in five people lack a <a href="https://www.nature.com/articles/ng0499_353" target="_blank">muscle protein called alpha-actinin-3</a> due to a single genetic change in the ACTN3 gene. The absence of alpha-actinin-3 became more common as some modern humans migrated out of Africa and into the <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0052282" target="_blank">colder climates</a> of Europe and Asia. The reasons for this increase have remained unknown until now.</p><p>Our <a href="https://www.sciencedirect.com/science/article/pii/S0002929721000136?via%3Dihub" target="_blank">recent study</a>, conducted alongside researchers from Lithuania, Sweden and Australia, suggests that if you're alpha-actinin-3 deficient, then your body can maintain a higher core temperature and you shiver less when exposed to cold, compared with those who have alpha-actinin-3.</p><p>We looked at 42 men aged 18 to 40 years from Kaunas in southern Lithuania and exposed them to cold water (14℃) for a maximum of 120 minutes, or until their core body temperature reached 35.5℃. We broke their exposure up into 20-minute periods in the cold with ten-minute breaks at room temperature. We then separated participants into two groups based on their ACTN3 genotype (whether or not they had the alpha-actinin-3 protein).</p>
<p>While only 30% of participants with the alpha-actinin-3 protein reached the full 120 minutes of cold exposure, 69% of those that were alpha-actinin-3 deficient completed the full cold-water exposure time. We also assessed the amount of shivering during cold exposure periods, which told us that those without alpha-actinin-3 shiver less than those who have alpha-actinin-3.</p><p>Our study suggests that genetic changes caused by the loss of alpha-actinin-3 in our skeletal muscle affect how well we can tolerate cold temperatures, with those that are alpha-actinin-3 deficient better able to maintain their body temperature and conserve their energy by shivering less during cold exposure. However, future research will need to investigate whether similar results would be seen in women.</p>
<h2>ACTN3's role</h2><p>Skeletal muscles are made up of two types of muscle fibres: fast and slow. Alpha-actinin-3 is predominantly found in fast muscle fibres. These fibres are responsible for the rapid and forceful contractions used during sprinting, but typically fatigue quickly and are prone to injury. Slow muscle fibres on the other hand generate less force but are resistant to fatigue. These are primarily the muscle you'd use during endurance events, like marathon running.</p><p>Our previous work has shown that ACTN3 variants play an important role in our muscle's ability to generate strength. We showed that the <a href="https://www.sciencedirect.com/science/article/pii/S0002929707620242?via%3Dihub" target="_blank" rel="noopener noreferrer">loss of alpha-actinin-3</a> is detrimental to sprint performance in athletes and the general population, but may benefit muscle endurance.</p><p>This is because the loss of alpha-actinin-3 causes the muscle to behave more like a slower muscle fibre. This means that alpha-actinin-3 deficient muscles are weaker but recover more quickly from fatigue. But while this is <a href="https://pubmed.ncbi.nlm.nih.gov/18650267/" target="_blank" rel="noopener noreferrer">detrimental to sprint performance</a>, it may be beneficial during more endurance events. This improvement in endurance muscle capacity could also influence our response to cold.</p>
<p>While alpha-actinin-3 deficiency does not cause muscle disease, it does influence how our muscle functions. Our study shows that ACTN3 is more than just the "gene for speed", but that its loss improves our muscle's ability to generate heat and reduces the need to shiver when exposed to cold. This improvement in muscle function would conserve energy and ultimately increase survival in cold temperatures, which we think is a key reason why we see an increase in alpha-actinin-3 deficient people today, as this would have helped modern humans better tolerate cooler climates as they migrated out of Africa.</p><p>The goal of our research is to improve our understanding of how our genetics influence how our muscle works. This will allow us to develop better treatments for those who suffer from muscle diseases, like <a href="https://www.nature.com/articles/ncomms14143" target="_blank">Duchenne muscular dystrophy</a>, as well as more common conditions, such as obesity and type 2 diabetes. A better understanding of how variants in alpha-actinin-3 influences these conditions will give us better ways to treat and prevent these conditions in the future.<img src="https://counter.theconversation.com/content/155975/count.gif?distributor=republish-lightbox-basic" alt="The Conversation"></p><p><a href="https://theconversation.com/profiles/victoria-wyckelsma-1213255" target="_blank">Victoria Wyckelsma</a>, Postdoctoral Research Fellow, Muscle Physiology, <em><a href="https://theconversation.com/institutions/karolinska-institutet-1250" target="_blank" rel="noopener noreferrer">Karolinska Institutet</a></em> and <a href="https://theconversation.com/profiles/peter-john-houweling-195466" target="_blank" rel="noopener noreferrer">Peter John Houweling</a>, Senior Research Officer, Neuromuscular Research, <em><a href="https://theconversation.com/institutions/murdoch-childrens-research-institute-1027" target="_blank" rel="noopener noreferrer">Murdoch Children's Research Institute</a></em></p><p>This article is republished from <a href="https://theconversation.com/" target="_blank" rel="noopener noreferrer">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/your-genetics-influence-how-resilient-you-are-to-cold-temperatures-new-research-155975" target="_blank" rel="noopener noreferrer">original article</a>.</p>
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Surprising Science
<p> While few people would contest that fruit and vegetables are good for you, there can be some confusion over how many servings of them you're supposed to eat in a given day. The USDA advises people to eat anywhere from five to nine a day, with international standards similarly converging around five or six, though some go much <a href="https://healthywa.wa.gov.au/Articles/F_I/Go-for-2-and-5" target="_blank">higher</a>. </p><p>Luckily, a new <a href="https://www.ahajournals.org/doi/pdf/10.1161/CIRCULATIONAHA.120.048996" rel="noopener noreferrer" target="_blank">study</a> that reviewed the health and diets of 100,000 people and combined it with meta-studies of the available data puts the debate over how many servings a day you should get to rest. </p>
<iframe width="730" height="430" src="https://www.youtube.com/embed/lW8C1W1Iefk" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> The researchers followed 66,719 women from the Nurses' Health Study and 42,016 men from the Health Professionals Follow-up Study to see how their diet affected their long-term health and mortality rates. Over the three decades of follow-ups, a clear, non-linear relationship developed between how many servings of fruit and vegetables people consumed per day and their risk of death. </p><p>That overall risk reached its lowest point at five servings a day—two of fruit and three of vegetables—with further increases having no additional benefit. What type of vegetable was consumed mattered as well, with starchy veggies like corn and potatoes having fewer benefits than other types. Fruit juices were also less helpful than just eating the fruit. On the other hand, leafy greens, carrots, citrus fruits, and berries all demonstrated health benefits. </p><p>The net benefits of this compared to only getting two servings a day (roughly what the typical American is <a href="https://www.ers.usda.gov/amber-waves/2019/june/americans-still-can-meet-fruit-and-vegetable-dietary-guidelines-for-210-260-per-day/" target="_blank" rel="noopener noreferrer">eating</a>) are notable. It averages to about a 13 percent lower risk of death from all causes, a 12 percent lower risk of death from cardiovascular disease, a 10 percent lower risk of death from cancer, and a 35 percent lower risk of death from respiratory <a href="https://www.sciencedaily.com/releases/2021/03/210301084519.htm" target="_blank" rel="noopener noreferrer">disease</a>. </p><p>To confirm the findings, the researchers conducted a meta-analysis of 26 other studies involving two million people. The results were similar, with the greatest reduction in mortality occurring at the five-a-day mark, though one study found that eating 10 servings a day offered some improvement on that.</p><p>For those who are <a href="https://www.eatforhealth.gov.au/food-essentials/how-much-do-we-need-each-day/serve-sizes" target="_blank" rel="noopener noreferrer">unsure</a>, a serving of fruit is one medium-sized fruit (like an <a href="https://www.heart.org/en/healthy-living/healthy-eating/add-color/fruits-and-vegetables-serving-sizes" target="_blank" rel="noopener noreferrer">apple</a>), half a cup of something canned, or a fourth of a cup of something <a href="https://www.halfyourplate.ca/fruits-and-veggies/what-is-a-serving/" target="_blank" rel="noopener noreferrer">dried</a>. When it comes to vegetables, a cup of leafy greens is a serving, as is half a cup of anything else which is fresh, canned, or frozen. </p><p>The study is not without issues. The dietary data is self-reported and could be inaccurate. Participants could also choose to eat better as their health declines, reducing the observed benefits. Above all, the study was observational, and causation cannot be proven. Despite these limitations, the study provides a great deal of support for the idea that eating more fruit and veggies is good for you.</p><p>Now to just settle the problem of getting them into your <a href="https://www.cdc.gov/obesity/downloads/strategies-fruits-and-vegetables.pdf" target="_blank" rel="noopener noreferrer">meals</a>.</p>
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