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Wednesday, May 4, 2016

PLOS Science Wednesday: Hi reddit, we’re Neelesh Patankar and Malcolm MacIver, and we published a paper in PLOS Biology showing a mechanically optimal method of swimming evolved independently in vertebrate and invertebrate swimmers – Ask Us Anything!

PLOS Science Wednesday: Hi reddit, we’re Neelesh Patankar and Malcolm MacIver, and we published a paper in PLOS Biology showing a mechanically optimal method of swimming evolved independently in vertebrate and invertebrate swimmers – Ask Us Anything!


PLOS Science Wednesday: Hi reddit, we’re Neelesh Patankar and Malcolm MacIver, and we published a paper in PLOS Biology showing a mechanically optimal method of swimming evolved independently in vertebrate and invertebrate swimmers – Ask Us Anything!

Posted: 04 May 2016 04:08 AM PDT

Hi Reddit!

My name is Neelesh Patankar, and I am the Charles Deering McCormick Professor of Teaching Excellence and Associate Chair of the Department of Mechanical Engineering at Northwestern University. Following my Ph.D. in Mechanical Engineering at University of Pennsylvania, I was a post-doctoral associate with Prof. Daniel D. Joseph at the University of Minnesota until 2000. I then joined the Department of Mechanical Engineering at Northwestern University as an Assistant Professor in 2000, and have been a Professor since 2011. My research area is developing computational methods for immersed bodies in fluids, applying computations to problems in biology (fish swimming, esophageal transport, rat whiskers), and designing textured surfaces for non-wetting, super-wetting, or anti-icing properties.

And my name is Malcolm MacIver, and I am a Professor with a joint appointment in the Department of Mechanical Engineering and Department of Biomedical Engineering at Northwestern University. I completed my Ph.D. in neuroscience at the Beckman Institute of Advanced Sciences and Technology at the University of Illinois, and my post-doc in mechanical engineering at the California Institute of Technology in Pasadena, joining Northwestern in 2003. My research includes the mechanical and neural basis of animal behavior, particularly the intersection of information harvesting and biomechanics, utilizing a variety of approaches spanning behavioral analysis, computer simulations, robotics, neurobiology, and mechanics.

We recently published a paper in PLOS Biology examining how diverse groups of aquatic animals, including vertebrates and invertebrates, evolved independently to exhibit a mechanically optimal method of swimming. Using computational modeling, measurements, and a robotic fish, we demonstrate that this "best way" to swim maximizes propulsive force and speed. There is some small amount of variability around the optimum in the many species we measured, but that variability is always within a relatively small zone where the decrease in performance is less significant. Our result touches on a long standing debate within biology about whether evolution is largely about chance, or about necessity. If we were to "rewind the clock" and restart evolution, would we get the same animals, or different ones? For example, birds evolved wings, and so did insects, but their last common ancestor did not have wings. This suggests that an aerial animal—on any planet with earth-like atmosphere—might have wings. The idea that evolution is therefore more about necessity than chance due to these kinds of repeated patterns is referred to as "convergent evolution." One of the unique contributions of our work is that we can quantitatively show where the optimum exists, while it has proven difficult to do so for other examples of convergent evolution.

We will be answering your questions at 1pm ET – Ask Us Anything!

@NeeleshPatankar, @malcolmmaciver

submitted by /u/PLOSScienceWednesday
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Why do the public keys for encryption using primes have to be prime? [Noob][Computing]

Posted: 04 May 2016 06:36 AM PDT

EDIT: WRONG TITLE!!!! I meant to say private keys.

I have just seen a post about the "illegal number" and began looking into prime number encryption.

My question is this:

Why do the private keys have to be prime?

Couldn't a bank, for example, just choose some random huge number as the public key and then say that unless you use the private key factors that they are using then you aren't able to get in?

What am I missing here?

submitted by /u/Skreaming
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How do braces and elastic bands correct an underbite or overbite without modifying the bone?

Posted: 03 May 2016 07:46 PM PDT

What Delineated The Periods of the Mesozoic Era?

Posted: 03 May 2016 09:01 PM PDT

Why are all the periods of the Mesozoic Era evenly divided? the Jurassic,Triassic and Cretaceous all seem to be roughly evenly divided.. Also what if dinosaurs hadn't been killed off? How would they have evolved?

submitted by /u/Jpf123
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What's the difference between connecting to a network with a Static IP and adding a static ARP cache entry?

Posted: 03 May 2016 07:25 PM PDT

Do they do the same thing? How do the consequences / behavior from the computer to router differ?

submitted by /u/flush_and_razer
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Do balloons filled with helium fly up inside of the iss?

Posted: 03 May 2016 03:19 PM PDT

Once a human reaches maturity, are there any cells left in the body that were there as an infant?

Posted: 03 May 2016 06:42 PM PDT

Just curious, since I read a discussion about the point at which someone/something is new (by replacement of parts).

submitted by /u/PM_ME_FUN_STORIES
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Evolution of Galaxies that have no Super Massive Black Holes in their centers?

Posted: 03 May 2016 01:13 PM PDT

It's still fascinating to me that such a HUGE galaxy like the A2261-BCG, which is 10 times wider than our galaxy, does not have a Super Massive Black Hole (SMBH) in its center. Will it form a new SMBH under gravity or will it eventually divide into smaller galaxies "dissolve"?

submitted by /u/n9s2cya
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Why electronic impact as ionization source doesn't produce multiple charged ions?

Posted: 04 May 2016 05:36 AM PDT

If photons are emitted/absorbed when an electron changes energy levels, how is it that light is constantly emitted?

Posted: 03 May 2016 08:06 AM PDT

In my college physics class we briefly talked about how photons are emitted when an electron loses energy by moving to a lower orbital. Similarly photons are absorbed when the electron gains energy and moves to a higher orbital.

OK, so how is it that atoms consistently generate light? Are electrons constantly gaining/losing energy, bouncing back and forth between orbitals?

submitted by /u/HoppyIPA
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A burning question: can bitumen catch fire during a forest fire?

Posted: 03 May 2016 11:04 PM PDT

The Athabasca oil-sands region is on fire. An entire city is being evacuated as I write this. People are wondering if the tar-sands themselves can catch fire if the fire decides to spread in that direction. There are (what I assume to be called) open-pit mines.

Is the apocalypse nigh? Will bitumen burn? If they do catch fire, how easy/or difficult would it be to put such a fire out?

submitted by /u/FATKIDfromFTWD
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What is a way to unfreeze liquid Nitrogen in an ice maker machine?

Posted: 03 May 2016 11:58 AM PDT

I form ice for snow cone machines and missed a day on one of them and now the liquid Nitrogen around the ice containers are frozen. I have a method, but was wondering if there was a quicker way to unfreeze the liquid Nitrogen.

submitted by /u/scifinotsyfyfan
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Why doesn't the Keplar space telescope focus on the area of space with our closest celestial neighbors?

Posted: 03 May 2016 11:55 AM PDT

As I understand it, the discoveries of habitable planets being made by Keplar are anywhere from 40 to over 1000 light years away. Since our closest star is ~4 ly away, and there's ~150 known stars within 20 ly, why wouldn't we focus our attention closer to home first? Does it have something to do with our vantage point within the galactic plane that makes it more valuable to take a long distance look or something like that?

submitted by /u/JimJalinsky
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What is in raisins and chocolate that makes them poisonous to dogs?

Posted: 03 May 2016 07:30 AM PDT

Why are low sodium diets suggested for high blood pressure when low sodium levels result in higher renin production and therefore higher blood pressure?

Posted: 03 May 2016 07:39 AM PDT

I've recently learnt at University about the renin-angiotensin system where low sodium levels result in increased renin production and therefore higher levels of angiotensin and aldosterone which result in more water conservation which ould lead to higher blood volume and therefore pressure. However, people always seem to suggest low sodium diets for those with high blood pressure issues. Why is this? Is my understanding of the renin-angiotensin system wrong or is there another mechanism in play?

submitted by /u/ZephrHD
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How effective are various lifestyle changes in improving mood, cognition, and reducing symptoms of mental illness, and how do we think they work?

Posted: 03 May 2016 03:28 AM PDT

By lifestyle changes I mean drastically improved diets, probiotics/supplements, mindfulness & meditation, introspection, exercise, etc.

Can we change our brains to a great extent with such interventions?

submitted by /u/gkjhkajshoeiwroiw
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What is Between Galaxies?

Posted: 03 May 2016 12:05 AM PDT

I'm not the brightest crayon in the box, but from what I've heard, galaxies are separated by large amounts of empty space. So I have a few questions.

Is there light in that space? I've been told that even when travelling between stars inside a galaxy, there is ambient light, but what about between galaxies? Or is it just completely dark?

Also, are there objects between galaxies? Rogue planets or stars maybe? I mean, i understand that statistically something must be there, but do we have any specific evidence of objects existing in these empty spaces?

If these are utterly stupid or, I don't know, not worth the time explaining to a dull boy like me, then let me know, I won't take offense. But, I do appreciate the answers, if any!

EDIT: I would just like to say thank you for all the answers coming in, you're all very knowledgeable and helpful people!

submitted by /u/CalbandPals
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Why does coke when heated with oxygen forms carbon dioxide and not carbon monoxide?

Posted: 03 May 2016 05:30 AM PDT

In the extraction of Iron from Haematite , why does Coke ,when heated with Oxygen ,only form Carbon dioxide and not Carbon Monoxide?

submitted by /u/ICSaturn
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How does sanitizer kill bacteria, and where does it go?

Posted: 03 May 2016 04:38 AM PDT

In the way we can detect a small change in temperature when running the tap, can we feel the same slight changes with extreme temperatures?

Posted: 03 May 2016 06:38 AM PDT

I understand that changing the temperature of water slightly can be felt but what about for example, the difference between my hand touching a 180C oven and a 220C oven? Will they just give that same burning pain or is there a vast difference between them?

submitted by /u/Stickyxo
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Tuesday, May 3, 2016

How can a maglev train be energy efficient?

How can a maglev train be energy efficient?


How can a maglev train be energy efficient?

Posted: 03 May 2016 06:20 AM PDT

According to Wikipedia, the energy used to keep the train stable above the rails is small compared to the energy used to counteract drag. With an object as heavy as a train, how is this possible?

submitted by /u/DrTobiasFunke23
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Why do some solvents separate from water when the solution freezes?

Posted: 03 May 2016 02:52 AM PDT

Like a bottle of lemonade made from mix for example. When it partially freezes there is a chunk of mostly just water ice, and a small amount of very concentrated solution. What is the process by which this happens?

submitted by /u/Smoked_Bear
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Why is it easier to feel the air blowing out of a fan than the air the fan is sucking in?

Posted: 02 May 2016 04:27 PM PDT

Is it possible to powerset a set infinitely many times?

Posted: 02 May 2016 10:54 PM PDT

and if so does that mean i have found a set so big that if i powerset it again it will still be the same set? because powersetting a set that have been powersetted infinitely many times one more time will not make it any bigger (because infinity+1=infinity duh!)

submitted by /u/N0TaCreativeUsername
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Can permanent magnets be explained through classical electromagnetism?

Posted: 02 May 2016 07:34 PM PDT

How effective is CPR for the immediate treatment of cardiac arrest?

Posted: 02 May 2016 05:50 PM PDT

Why did the black death just stop?

Posted: 02 May 2016 01:14 PM PDT

I know there are still a handful of cases that happen each year, but for the most part the plague just seemed to disappear. Why hasn't this also happened with other diseases like the common cold?

submitted by /u/xJavan
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Do bioluminescent creatures only produce light in the visible spectrum?

Posted: 02 May 2016 10:16 AM PDT

Is Calculus an on-going research area ?

Posted: 02 May 2016 10:31 AM PDT

Hi redditors ! I think the question speaks for itself but I'll try to be more concise, when I say 'calculus' I mean 'pure calculus', I know calculus is useful in plenty areas of maths but I was wondering if research is still going on about it.

submitted by /u/ThatSlowBerry
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How do superconductors work? What changes when they are super cooled?

Posted: 02 May 2016 06:05 PM PDT

What is the direct cause of them becoming electromagnets when they are cooled to really low temperatures?

submitted by /u/sauce49
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How does a satellite know its location in space, so as to adjust its thrust/trajectory to avoid collision with objects and find a stable orbit?

Posted: 02 May 2016 04:28 PM PDT

Can mass be relative?

Posted: 02 May 2016 04:22 PM PDT

Since velocity is relative based on frame of reference, Kinetic Energy is relative. Energy and mass can be exchangeable so does that mean that an object can have relative mass?

submitted by /u/SeryuSenga24
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How far out could we maintain a geosynchronous orbit?

Posted: 02 May 2016 03:22 PM PDT

Would it be possible to have a satellite maintain a geosynchronous orbit beyond our moon? I was thinking of this today in regards to having another lense that could magnify our current telescopes beyond what we have. Whether that be an earth based or space based like Hubble or in the near future Web.

submitted by /u/PurpEL
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Does being upside down have any negative effects on the brain due to the blood rushing to your head?

Posted: 02 May 2016 04:04 PM PDT

I've had this question for a while, it's extremely common for someone in gymnastics or gymnastics-like programs to do things like handstands or any other exercise that requires the body to be upside down for anywhere up to a few minutes at a time. While I'm pretty sure it's completely fine to do this every now and then, would doing this at a high frequency, say every day for months or even years have any negative impacts on the brain due to the large amount of blood rushing to your head?

submitted by /u/x_d_o
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Does our method of finding planets vastly restrict the amount of planets we discover?

Posted: 02 May 2016 04:05 PM PDT

I think somewhere in the nebula origin hypothesis for Solar Systems, planets tend to all "flatten out" onto the same plane orbiting a star. I've read that many planets are discovered in other solar systems by watching the newfound planet traverse the star and blocking a small fraction of the light emitted.

Wouldn't this method of finding new planets miss any planet that doesn't directly cross the star? From Earth's perspective, wouldn't this only reveal a tiny fraction of planets nearby? I know other planets can be found based on gravity, but isn't the star method the primary method, or am I missing something? Interested to hear what you guys think!

submitted by /u/Treebarks8
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Can it rain sand?

Posted: 02 May 2016 03:38 PM PDT

I live a few miles from the coast and sand is on everything. I know the winds are responsible for most of it but I was wondering if any of it comes down with raindrops from being evaporated out of the ocean.

submitted by /u/ChooseAUs3rnam3
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What are the "remnants" of Halley's Comet?

Posted: 02 May 2016 05:52 PM PDT

I read this article and it stated that two meteor showers, the Eta Aquarids and the Orionids both give us a chance to view the remnants of Halley's Comet. What does this mean, that Halley's Comet destroyed a bunch on space stuff that was in its trajectory and this is debris or that Halley's Comet was struck and is broken up/breaking down and the Comet's pieces are falling toward Earth creating the shower?

submitted by /u/ghasp
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Were there ever any aquatic dinosaurs?

Posted: 03 May 2016 05:04 AM PDT

I'm aware there were prehistoric swimming reptiles (plesiosaurs, mosasaurs, ichthyosaurs, etc.), but as I understand they belonged to class: reptilia, so they weren't dinosaurs proper.

It seems like the major classes of modern animals--reptiles, birds, and mammals--have all at some point gone back to the sea (e.g., sea turtles, penguins, wales). Are there any examples of aquatic animals belonging to class: dinosauria? In other words, are there any examples of aquatic dinosaurs that clearly evolved from a terrestrial dinosaur ancestor?

Sorry if this is a naive or out-of-date question. I'm not familiar with dinosaur phylogeny.

submitted by /u/fablong
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Did the Dust Bowl improve agricultural production in areas where top soil was deposited by winds?

Posted: 02 May 2016 01:14 PM PDT

Is air resistance at 80 mph the same as wind up to 80 mph?

Posted: 02 May 2016 03:45 PM PDT

I was in the car with a friend going about 80 mph, and he stuck his arm out the window. Would his body be subject to the same forces if he were just sticking his arm out a house window and winds were blowing 80 mph? If not, why are they different?

submitted by /u/geetar_man
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When an airliner flies by, there is a white cloud emitted just behind the plane. What is this composed of, and why does it only happen sometimes?

Posted: 02 May 2016 12:39 PM PDT

What physical properties make an object sharp?

Posted: 02 May 2016 09:27 AM PDT

Monday, May 2, 2016

What is the modern consensus in Psychiatry regarding the efficacy of anti-depressants vs placebo?

What is the modern consensus in Psychiatry regarding the efficacy of anti-depressants vs placebo?


What is the modern consensus in Psychiatry regarding the efficacy of anti-depressants vs placebo?

Posted: 01 May 2016 09:24 AM PDT

I didn't even know until recently that for at least a decade there has been something of a controversy over whether the effects of anti-depressant medications on depression can be chalked up entirely to placebo or not, sparked mainly by work by Irving Kirsch who seems to be on a bit of a crusade against anti-depressants. I had taken it for granted until now that obviously they must have some active effect.

I've tried to make sense of the controversy by reading what I can of Kirsch and the responses but a lot of it goes over my head. It seems like it's generally acknowledged that anti-depressants usually have a very modest effect except in extreme cases where they can have a serious effect? It's hard for me to find much actual sources on this to read however which are not the standard stuff about the evils of big pharma trying to poison our brains.

submitted by /u/Akton
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Can modern chemistry produce gold?

Posted: 02 May 2016 05:02 AM PDT

reading about alchemy and got me wondered.

We can produce diamonds, but can we produce gold?

submitted by /u/koreankiwitea
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In terms of "brain health", does reading, chess, and other "smart" activities actually do anything of benefit to the brain? Likewise, wouldn't cardio be beneficial to overall health for the brain?

Posted: 01 May 2016 06:48 AM PDT

As I understand, neurons in the brain die with age, and they don't come back (or if they do, in a limited way). As a kid, I always heard that playing video games/watching TV would "melt" my brain (which doesn't seem right). Meanwhile, activities such as chess, or card games, or reading are suppose to be "good" for the brain. How exactly are some activities good for the brain, and what is the mechanic within in the brain that makes these tasks helpful to the brain?

Likewise, in terms of overall brain health, wouldn't cardiovascular exercises help your brain? As I understand, parts of the brain receive blood from veins (capillaries?), and this provides oxygen to brain cells, which is important to their overall health. Do I have this right, and if so, do we know how cardiovascular exercises overall brain health?

Thanks!

submitted by /u/Reflektor18
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Einstein explained gravity as a distortion of space-time due to mass. Where does the graviton fit in?

Posted: 01 May 2016 07:29 AM PDT

A particle and a distortion of space-time continuum seem to be two opposing explanations for gravity.

submitted by /u/paleRedSkin
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If I were to analyse the DNA of a newborn baby, and then wait 80 years before analysing that person's DNA once more, how genetically dissimilar might I expect the two samples to be?

Posted: 01 May 2016 06:39 AM PDT

Why do adults need hormones like estrogen, progesterone and testosterone, but children can live with low levels of them all the way until puberty?

Posted: 01 May 2016 08:26 PM PDT

How does a boomerang work?

Posted: 02 May 2016 04:34 AM PDT

Do different languages compel native speakers to think in different ways?

Posted: 01 May 2016 07:50 PM PDT

Some linguists, such as Noam Chomsky, believe language is the basis of cognition. If language is the tool kit by which we think, is it possible that differences between languages give rise to differences in thought in native speakers? In other words, is it poosible that a Bantu speakers might have a better grasp on some concepts than English speakers or vice versa due to particular aspects of their respective languages?

submitted by /u/ienjoyapples
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Why do fans always always go off-high-medium-low and not off-low-medium-high?

Posted: 01 May 2016 01:07 PM PDT

I always hate that I can't tell if a fan is off or not and always end up pulling the cord like 20 times over and over again trying to figure out if it's off or not. Wouldn't it make the most sense to have it go from the loudest and most obvious setting (high) to the off position? Is there something with the design of fans that prevents this?

submitted by /u/StankCheez
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What does it mean to understand something or not understand it? What's going on in the brain and conscientiousness that allows this to happen?

Posted: 01 May 2016 07:55 PM PDT

When I look at a math problem and don't understand it, why don't i understand it?

When I look at a science problem i generally can understand it.

What goes on in the brain/inner thoughts that allow you to hit the wall or jump over it mentally?

submitted by /u/PuckTheBruins
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How does a bat construct its airfoil and is a fused clavicle beneficial for flying?

Posted: 01 May 2016 09:02 PM PDT

What accounts for the ability of slow cooker liners to not melt or stretch extensively under such heat?

Posted: 01 May 2016 07:12 PM PDT

New studies link anticholinergic drugs to increased risk of brain damage in elderly people... Is there evidence of similar effects in younger people? Is there any reason why these drugs would be fundamentally safer for non-elderly people?

Posted: 01 May 2016 07:33 AM PDT

How does a cloaca filter excretion waste and sexual fluids in Reptiles/Amphibians/Birds?

Posted: 01 May 2016 09:01 PM PDT

How does this little plastic piece make patterns when you shine a laser through it? Shouldn't the laser just be diffused?

Posted: 01 May 2016 12:36 PM PDT

What makes the Fibonacci Sequence so "special"? Couldn't you find similar patterns with any arbitrary set of operations between numbers?

Posted: 01 May 2016 04:40 PM PDT

I was watching this Numberphile video and it got me thinking. The patterns he talks about don't really seem all that surprising to me. If you started performing the same operations over and over again in a set manner with numbers, you're bound to start seeing patterns. What makes this particular set of operations (adding the previous two to get the next) so special?

submitted by /u/sts816
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How are we able to understand misspelled words?

Posted: 01 May 2016 06:28 PM PDT

How and why are we able to see past typos and understand what they originally mean, instead of pausing and asking ourselves what this new word is? For example if you see "spellig", you'll most likely think the original word was supposed to be "spelling", especially if it were in the context of a sentence. If we can differentiate between visual shapes (we know a square is a square, and not a triangle), then what is different in this case? And finally, to what extent would we no longer be able to recognize a typo from the intended word?

submitted by /u/Thegreatmochi
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If a baby were to be placed near the edge of a cliff, would it know not to fall off?

Posted: 01 May 2016 09:48 AM PDT

If so, how would it know? If not, when does this skill develop and how does it work?

I'm assuming this experiment hasn't been conducted before, and for good reason.

submitted by /u/preetcolors
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Why is it more difficult to move my fingers when they're cold?

Posted: 01 May 2016 03:40 PM PDT

For example: after jogging in the rain or walking around without gloves in winter?

My fingers are unable to grip as hard as they normally can and my motor skills aren't as precise. (I've noticed this while gaming, like this guy.)

submitted by /u/VladymyrPutin
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In the movies, when someone is shot directly in the head, they die instantaneously. How true is that? Also, why is it that we die so quickly from something entering our brain?

Posted: 01 May 2016 06:12 AM PDT

How well would a bird fly in zero-g?

Posted: 01 May 2016 06:39 PM PDT

How well would a bird fly in zero-g? Would smaller birds fare better than larger birds? Would hummingbirds be better or worse than other birds? Has this been done before?

submitted by /u/memercopter
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If we place a perfect sphere on a flat surface, how much of the sphere touches the surface?

Posted: 01 May 2016 04:13 PM PDT