sci-lit

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Top 5 misconceptions about evolution: A guide to demystify the foundation of modern biology.

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From Superbubbles to Galactic Fountains

Nebula NGC 1929 contains just the kind of superbubble that Astrophysicists think could cause a Galactic Fountain. Even though this nebula is not causing a fountain, it is theorized that similar nebula are causing Galactic Fountains within our Milky way galaxy. The illustration bellow shows how massive Galactic Fountains spew hot ionized gas away from our galactic disk to form Galactic Corona:

Supernova explosions within the galactic disc drive hot gas out of the disc, creating so-called galactic fountains that contribute to the formation of a halo of hot gas around the Milky Way. As the gas rises above and below the disc, reaching heights of a few kiloparsecs (more than 6,000 light-years!), it emits radiation and thus becomes cooler, condensing into clouds which then fall back into the disc, in a fashion that resembles a fountain.

Credit: ESO VLT/ESA/Fountains and Pumps

The Anatomy of a Constellation

In a cave system at Lascaux, southern France, Paleolithic paintings span the walls, dating back 17,300. Within the rocky tapestry, a picture of two bulls is adorned with clusters of dots—Orion’s belt, Taurus, the Pleiades and the Hyades clusters… What is thought to be the first recorded representation of the stars. For as long as we’ve walked this Earth, humans have been looking up to the sky and finding meaning in the randomness. Nearly every culture on Earth created patterns in the stars and attributed their own mythical stories to them, giving birth to what we know as constellations. Though they look like neighbours from our vantage point, in reality the stars that make up constellations might be thousands of light years apart. They’re just a matter of perspective, but they serve an important purpose: helping us navigate our way across the vast sky. On a dark night you can see over a thousand stars, so by recognising patterns we can break the sky down and move among the stars more easily. Constellations become mnemonics. Because of the relative movements of the Earth and Sun, constellations are divided into two groups: circumpolar constellations, which are always in the sky, and seasonal constellations, which rise and set according to season. Constellations change groups depending on your latitude, hence why the different hemispheres see different stars. In the past, farmers would have known which constellations signalled the comings of certain seasons, and so knew when to plant and when to harvest. Sailors and explorers have also long since been dependent on stars for navigation, and different cultures have all had different uses for their own stars. But in 1929, the International Astronomical Union consolidated them, officially setting out “modern” constellation boundaries and defining the 88 ones we know today, pictured above.

Truth is sought for its own sake … Finding the truth is difficult, and the road to it is rough. For the truths are plunged in obscurity … God, however, has not preserved the scientist from error and has not safeguarded science from shortcomings and faults. If this had been the case, scientists would not have disagreed upon any point of science…

Therefore, the seeker after the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and deficiency.

Thus the duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.

— 

Ibn al-Haytham, Father of the Scientific Method - ‘Doubts on Ptolemy’

Ibn al-Haytham was a devout Muslim, and his theology influenced his outlook on science. He believed that God made the world difficult to understand and that skepticism and critical analysis were the only way to illuminate God’s creation. He is thus an excellent counterexample to the idea that religious belief necessarily stifles scientific thought.

“Scientific literacy is the vaccine against charlatans and con artists whom prey on the fears and gullibility of others. It’s no longer acceptable to passively dismiss science as merely a niche interest a certain percentage of the population are passionate about. Understanding science is not limited to those with whom it seemingly comes naturally. Those who have a passion for science have been typecast as nerds or geeks because of how they make us feel about ourselves and our own inability to love learning the way they do.

However, there’s no iron curtain separating them from us; nor do they have better genes, or brains, even. One’s propensity to embrace uncertainty and value knowledge is solely crafted by the environment they’ve developed within. Parents or caregivers who read to them, were seen reading themselves, and provided an enriching atmosphere where the fire of curiosity we begin this life with is fueled in such a way that questions are encouraged. Teaching a child how to investigate reality, fine tune their questions, and actively promote the perspective that education is not something you ever finish will create not nerds, geeks, or egg heads, but lifelong learners whose horizons are always expanding.

Each of us are the result of the environment we’ve been amidst the influence of. And we’re nearly at the point where all 7+ billion of us have access to resources and information which have the ability to disrupt the circumstances of wherever (and however) we were or were not raised, enhancing our respective ability to actually change ourselves. The implications of this are (to borrow a line from Carl Sagan’s book ‘Cosmos’) rich beyond measure.

The most impactful introduction I was ever provided regarding science did not come from my parents, family, coaches, or teachers; but from a Cornell professor of astronomy I never physically met or spoke to. He told me that "Science is more than a body of knowledge,” more than a series of facts and stale knowledge about what things are called. “Science” he said, “is a way of thinking. A way of skeptically interrogating the universe with a fine understanding of human fallibility.” Meaning, being humble enough, always, to understand that the easiest person to fool is ourselves.

Once I approached science in this way - as actual methods and tools - everything changed for me. “When you’re scientifically literate, the world looks very different to you” Neil deGrasse Tyson once stated in an interview, discussing his approach to parenting, and in my opinion, education at every level would benefit by having all subjects interdependently communicated and bridged together in this way. From tabloid headlines and magazine articles to mainstream “news” media and politics, science communication is essential - imperative - to a society desperately in need of critical thinkers.

“Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works.”
– Carl Sagan

io9.com
80% Of Americans Support Mandatory Labels On Foods Containing DNA. DNA!

“WARNING: This product contains deoxyribonucleic acid (DNA). The Surgeon General has determined that DNA is linked to a variety of diseases in both animals and humans. In some configurations, it is a risk factor for cancer and heart disease. Pregnant women are at very high risk of passing on DNA to their children.”

There are no dumb questions on this blog, my friend! I’ll bet a bunch of people are currently reading this thinking MAN I’D REALLY LIKE TO KNOW THAT TOO.

So, let’s talk CHEMISTRY. When onions are grown, they absorb sulfur from the earth, which creates a kind of volatile, organic molecule called amino acid sulfoxides. These form sulfenic acids in the onion cells, and they’re kept separate from enzymes (complex proteins that cause chemical changes). By cutting an onion, you’re actually breaking its cells–so enzymes are now free to mix with the acids. Together they form a sulfur gas called propanethiol S-oxide, and this wafts right up towards your eyes without mercy.

When it reaches them, the gas reacts with the water in your eyes and forms a mild sulfuric acid, which is what causes the REALLY irritating pain. As a defence mechanism, you reflexively tear up to wash the irritant away.

So when you cry, it’s not due to being emotional about cooking, it’s because you have SULFURIC ACID IN YOUR EYES.

That’s pretty badass.

Seriously though, I can’t emphasize enough how amazing Khan Academy is. Khan Academy is completely free, and teaches everything from Humanities to hard sciences. Khan Academy has delivered over 300,000,000 lessons, and its goal is to provide ‘a free world-class education for anyone anywhere’. Khan Academy has proven to be invaluable to me, as well as several of my peers, and I highly recommend it for anyone who is looking to expand their interests and their education. 

www.khanacademy.org

anonymous asked:

Can we talk about the double slit experiment?

Heck yes we can. HIGH SCHOOL PHYSICS COME AT ME.

Essentially, the double slit experiment shows that light exhibits dual wave/particle behaviour. It was first offered up by Thomas Young in the late nineteenth century, which is why it’s called the Young’s Double Slit Experiment.

Here’s how it goes down: A monochromatic (single colour/wavelength) light is shone towards a blank screen, and placed between them is a screen with two parallel slits cut into it. If light is just a particle, then it would simply shine through the slits and hit the blank screen in two lines, kind of how spray paint can follows the shape of a stencil. But it doesn’t. It shines on the screen as parallel bands, or fringes.

(Image Credit)

This is because in this instance, light is acting like a wave, so when it passes through the slits, it diffracts—i.e., it spreads out after passing through a narrow opening. This happens from both openings, so  instead of two straight beams of particles, the light becomes two diffracting waves, like this:

(Image Credit)

As they both hit the screen, at some points the waves will meet crest-to-crest, which increases the intensity of the wave (constructive interference), and at other points they’ll meet crest-to-trough, which decreases the intensity of the wave because they cancel each other out (destructive interference). On the screen, the bright lines correspond to the maximum intensities, and the dark lines correspond to the minimum intensities. The combination of these is called an interference pattern.

This experiment is important because it shows that photons can also act as waves, since particles don’t diffract, thus demonstrating the principle of wave-particle duality!

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Kihansi Spray Toad (Nectophrynoides asperginis)

…is a small species of toad that was once native to the spray zone around the Kihansi waterfalls in Tanzania. Unfortunately after the construction of the Kihansi dam, the species became extinct in the wild. Luckily the toads are surviving in captivity, as several zoos have taken up breeding programs with hopes to one day to reintroduce them. In 2012 scientists reintroduced a test population of 48 toads into the gorge, and hope to have 1,800 toads in the wild soon.

Phylogeny

Animalia-Chordata-Amphibia-Anura-Bufonidae-Nectophrynoides-asperginis

Image Source(s)

Scientific Literacy

Can you tell me why stem cells are so important, or why the moon has phases, or how old the universe is? Can you explain what carbon dating is, or the difference between nuclear fusion and nuclear fission, or why it’s hotter in summer than it is in winter? If you can’t, then you might not be scientifically literate. This is problematic, because science is not only really damn awesome, it’s also important. Today, tomorrow, or next week, you’re going to see a news headline about an advance in stem cell research or a warning about climate change, and even if you don’t understand what it means, it’s definitely going to affect your life. Science clearly isn’t being taught or communicated as effectively as it should be—sometimes even scientists themselves are scientifically illiterate outside of their specific field of study, which is ABSURD. Our world is becoming more and more technological and scientific every day, so everyone needs to have fundamental background knowledge in order to understand and be actively involved in scientific issues. This doesn’t mean you need to do what a scientist does—like, you don’t have to build a robot to appreciate the Mars rovers any more than you have to build a plane to appreciate flying. But the Mars rovers exist, and they impact your world, and they’ll impact the world of your children too. Becoming scientifically literate should be like learning how to read: everyone should be taught basic scientific facts, concepts, vocabulary, history and philosophy. Like reading, it’ll open your eyes and enrich your life, because science is exciting—our universe is beautiful and extraordinary and exquisite, and everyone should learn about it. For starters, check out Tumblr’s #science tag, my links page, and the #sci-lit tag, which I’m aiming to take over and use to build up a database of core concepts of science. Go forth and seek knowledge!

Have you ever stopped to think just how amazing the molecular machinery that is responsible for the variance of life on earth is? Here are just a few reasons why DNA is so cool:

  • It is responsible for the variance of all life on earth using only 4 bases. Every living organism uses the same code of A’s, C’s, G’s, and T’s to store their genetic code.
  • The complete human genome takes up 3 gigabytes of data
  • The DNA in one E. coli cell is over 1000 times as long as the cell itself
  • The DNA in one of your cells is about as tall as you
  • The DNA in all of your cells can stretch to the moon and back over 6000 times
  • It can replicate itself billions of times with an astonishing 0.000002% error rate
  • Humans replicate DNA at about 50 base pairs per second, and if you think that’s fast, E. coli can replicate DNA at 1000 base pairs per second
  • You share 99.9% of your DNA with all the other humans on the planet
  • The human genome isn’t even the largest on the planet. Corn and Salamanders have larger genomes than us, proving that we are wrong to think we are the most complex species on earth
  • It would take a human working around the clock over 50 years to type out the entire human genome
  • Only 2-3% of your genome actually codes for genes
  • Normally DNA codes for RNA, which in turn codes for proteins. This is referred to as the Central Dogma, and we have long since believed this process could only take place in that order. However we have since learned that retroviruses, such as HIV, can break this rule and code DNA from RNA.
youtube

The always charming Alex Danis of Bite Sci-zed has performed the ultimate act of science. She had her DNA genotyped! Using 23andme she finds out a dark secret from her past, Neanderthal blood. If you love SNPs, phylogenetics, and medical breakthroughs, then you’ll love this week’s episode. 

Celestial Pinball

It’s not very powerful or economical to propel solar-system-traversing spacecrafts by jet propulsion alone—they need help, and it just so happens that there are a few giant celestial bodies willing to lend a hand. In 1961 scientists proposed a technique that allowed the gravity of planets to give spacecraft a boost as they flew by, accelerating them and/or changing their direction. Basically, the technique relies on the relative movement and gravity of the planet to ‘fling’ the spacecraft on: the spacecraft first accelerates because it falls towards the planet due to gravity, then speeds past it—and as the planet moves in orbit around the sun, away from the craft, the spacecraft gets a kick and shoots off with added speed and often a new direction. It’s like celestial baseball: a ball is pitched and a bat is swung with as much force the batter can muster, and wham—the ball is knocked in a new direction with more speed. A planet and a spacecraft only interact with each other gravitationally, but the result is the same—an object that has lots of momentum transfers a little bit to another object. This means that the planet actually loses a bit of momentum, and therefore speed, due to the law of conservation of momentum. But planets are so comparatively huge that it nearly doesn’t matter. Both Voyager missions picked up over 64,000 km/h from Jupiter, and over the next five billion years, Jupiter will only decelerate just enough so that the planet’s orbit will fall a single millimetre short of where it would have been if the Voyagers had never passed by. This ‘gravitational slingshot’ saves time and fuel, and costs nothing but precise planning and a little bit of ingenuity. The main drawback to is that the planets have to be lined up just right, so missions have to fly within a certain time window. The Voyager 2 mission, for example, took advantage of a rare line up: it pinballed past Jupiter, Saturn, Uranus, and Neptune, and finally was flung it out towards the stars.

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The difference between frogs and toads? Nothing apparently.

  • by Henry Rothwell

“There’s a particularly fascinating dig going on at the moment. It’s an investigation into the Mesolithic archaeology around Amesbury, Wiltshire. Obviously every story generated about the excavations has to feature the word ‘Stonehenge’. There are two reasons for this – the first is that it is, undeniably, close by. The second is that UK journalists seem unable to cope with the concept of prehistory unless it includes a reference to Stonehenge, gold, or cannibalism. Some, I imagine, may dream of the day when all three words can be used in a single headline. Others, the older hacks, dread the idea, realising that there would be no way of topping it, bringing an end to easy page filling Stonehenge stories.

Damn you Stonehenge. It would have been better for British prehistory if instead of removing a section of the A344, we’d have crushed your useless rocks and used the gravel to build a new road. That way at least some lesser known archaeology would have got a look in.

Or would it? To illustrate the point (Stonehenge mentions aside) the press were recently given the opportunity to cover the Blick Mead excavation findings. There are many remarkable things to be pointed at and spoken of in tones of awe and wonder, but instead they picked up on the fact that a charred toad’s leg was part of an assemblage of animal remains from 8,000/10,000 years ago.

But even that’s not interesting. They had to change it to a frog’s leg. And then turn that into some faintly (faintly?) xenophobic guff about having beaten the French to the snack they’re so famous for. Or that we deliberately tie them to for some cheap borderline racist fun. So Mesolithic frog’s legs then. Anything else we need to cover?” (read more).

***Bring on the snark.

(Source: The Digital Digging Blog)