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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
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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
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Sunday, May 1, 2016

If I were to drop an object, a bowling ball, down an infinitely long vacuum tube, what speed could it reach?

If I were to drop an object, a bowling ball, down an infinitely long vacuum tube, what speed could it reach?

If I were to drop an object, a bowling ball, down an infinitely long vacuum tube, what speed could it reach?

Posted: 30 Apr 2016 05:39 PM PDT

Given that an object can't travel faster than the speed of light and that there is no resistance which of these two overrides the other?

submitted by /u/FrenchButcher
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Why does my congestion go away when my body is in hot water?

Posted: 30 Apr 2016 09:34 PM PDT

I'm extremely congested most of the time and have found that immersing my body in hot water really alleviates my congestion. There's no real steam in the room, so what is it that's making it so much easier for me to breathe?

submitted by /u/burf
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How or why does moon sometimes appear bigger and in different colour?

Posted: 30 Apr 2016 06:16 PM PDT

Can sound be used as a catalyst for chemical reactions?

Posted: 30 Apr 2016 01:41 PM PDT

Is the Gravitational Constant "constant" as the Universe ages and expands?

Posted: 01 May 2016 06:42 AM PDT

Is the Gravitational Constant of today the same as that of the one from right after the Big Bang and will it be the same value in 10 billion years?

submitted by /u/sldfghtrike
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Would flames be shorter/taller under higher/lower gravity?

Posted: 01 May 2016 04:47 AM PDT

If I had a bio dome on the moon and made a bonfire would the flames be taller because of the lower gravity? Would you see a clear difference? What about on a huge planet? Or the sun? Does a bio dome bonfire on the sun have short little flames?

submitted by /u/cheeseismurder
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Why are alpha particles stable?

Posted: 01 May 2016 06:23 AM PDT

Why don't radionuclides emit particles of made 4 neutrons? What makes the alpha particle arrangement more energetically favourable than a neutron analogue?

submitted by /u/moisttoejam
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If the moon is geologically dead, how will we find metal ores and what will their concentrations be like?

Posted: 01 May 2016 12:54 AM PDT

Clarification:

On the moon, rocks tend to be about half silica with mineral impurities of aluminate (up to 30%), Ilmenite (up to 10%), and Ferrous oxides (up to 15%). The concentration of these minerals would not make them profitable to produce metals from by earth standards, where we tend to use ores like Magnetite (70%+) Goethite (60%+), and limonite/siderite (40%+) for pig iron production.

Hematite, Magnetite, and Goethite are mostly formed by interactions with water. Since the moon has no water to form sedimentary strata, would it stand to reason that the Moon's iron would not form concentrated ores like this?

Chalcocite and Chalcopyrite are mostly found in igneous rocks. Since the moon is not geologically active, would these crystal formations be present? Would veins of copper-bearing crystals have formed during the initial cooling after the impact even that created the moon?

Assuming the moon has no sedimentary deposits, we're excluding all alluvial and stratiform ores, all hydromagmatic deposits, all hydrothermal deposits, and all epigenetic deposits. This means zero metasomatic deposits as well, right?

Does this mean the only metals we will find are astrobleme related, or magmatic, I'm guessing?

Due to a lack of magmatic dynamism in the Moon's history, would this mean that the moon's metal deposits would have sunk to the core during formation, or would they have been left interspersed with the crust?

submitted by /u/PM_ME_JAR_JAR_NUDES
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How do we have pictures of Milky way?

Posted: 01 May 2016 01:15 AM PDT

What's the cardinality of negative infinity to positive infinity?

Posted: 30 Apr 2016 06:32 PM PDT

That is, the set of integers between negative and positive infinity. Is it equal to aleph-null? It seems like it should be bigger than the set of natural numbers.

submitted by /u/gprime312
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Why is it considered easier to hit a home run on a ball traveling faster rather than slower?

Posted: 30 Apr 2016 01:06 PM PDT

I watch baseball and I've heard them mention that the fact that it's a fastball made it go far enough to go over the wall.

submitted by /u/sixarmedOctopus
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A balloon filled with helium goes in the opposite direction of earth's gravity. Not only does it overcome the force, but it also travels up. What would happen to a balloon in deep space? Would the helium stay put or would the balloon split and the helium go in all directions?

Posted: 30 Apr 2016 08:23 PM PDT

What does a colorblind person see in a room with only red light?

Posted: 30 Apr 2016 11:10 AM PDT

For example, a darkroom for photo developing with only pure red light. Would the room appear to have the same amount of "lightness" but appear gray in color? Or would it be like there is no light at all? If the circumstances would be different for different types of colorblindness/different color light, I'm curious about that as well.

submitted by /u/soyouwannabeapanda
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Does it take more energy to heat liquid water or frozen water?

Posted: 30 Apr 2016 08:07 PM PDT

It's my understanding that water takes more energy to heat due to the increased density of atoms. So would that mean that ice takes less energy?

submitted by /u/LtDominator
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While under the influence of LSD, can you transfer the drug into that of an unsuspecting animals while petting it?

Posted: 30 Apr 2016 06:27 PM PDT

"Never pet animals while tripping" is something I have heard many times. The "logic" is somehow the sweat on your hands or through some other medium allows the drug in your system to be transferred into the animal's system. Does this have any actual scientific backing or logic?

submitted by /u/wikipediavalidsource
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