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Wednesday, September 27, 2017

AskScience Panel of Scientists XVII

AskScience Panel of Scientists XVII


AskScience Panel of Scientists XVII

Posted: 07 Aug 2017 01:16 PM PDT

Please read this entire post carefully and format your application appropriately.

This post is for new panelist recruitment! The previous one is here.

The panel is an informal group of redditors who are either professional scientists or those in training to become so. All panelists have at least a graduate-level familiarity within their declared field of expertise and answer questions from related areas of study. A panelist's expertise is summarized in a color-coded AskScience flair.

Membership in the panel comes with access to a panelist subreddit. It is a place for panelists to interact with each other, voice concerns to the moderators, and where the moderators make announcements to the whole panel. It's a good place to network with people who share your interests!


You are eligible to join the panel if you:

  • Are studying for at least an MSc. or equivalent degree in the sciences, AND,

  • Are able to communicate your knowledge of your field at a level accessible to various audiences.


Instructions for formatting your panelist application:

  • Choose exactly one general field from the side-bar (Physics, Engineering, Social Sciences, etc.).

  • State your specific field in one word or phrase (Neuropathology, Quantum Chemistry, etc.)

  • Succinctly describe your particular area of research in a few words (carbon nanotube dielectric properties, myelin sheath degradation in Parkinsons patients, etc.)

  • Give us a brief synopsis of your education: are you a research scientist for three decades, or a first-year Ph.D. student?

  • Provide links to comments you've made in AskScience which you feel are indicative of your scholarship. Applications will not be approved without several comments made in /r/AskScience itself.


Ideally, these comments should clearly indicate your fluency in the fundamentals of your discipline as well as your expertise. We favor comments that contain citations so we can assess its correctness without specific domain knowledge.

Here's an example application:

 Username: /u/foretopsail General field: Anthropology Specific field: Maritime Archaeology Particular areas of research include historical archaeology, archaeometry, and ship construction. Education: MA in archaeology, researcher for several years. Comments: 1, 2, 3, 4. 

Please do not give us personally identifiable information and please follow the template. We're not going to do real-life background checks - we're just asking for reddit's best behavior. However, several moderators are tasked with monitoring panelist activity, and your credentials will be checked against the academic content of your posts on a continuing basis.

You can submit your application by replying to this post.

submitted by /u/AskScienceModerator
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Why do we consider it certain that radioactive decay is completely random?

Posted: 26 Sep 2017 04:57 PM PDT

How can we possibly rule out the fact that there's some hidden variable that we simply don't have the means to observe? I can't wrap my head around the fact that something happens for no reason with no trigger, it makes more sense to think that the reason is just unknown at our present level of understanding.

EDIT:

Thanks for the answers. To others coming here looking for a concise answer, I found this post the most useful to help me intuitively understand some of it: This post explains that the theories that seem to be the most accurate when tested describes quantum mechanics as inherently random/probabilistic. The idea that "if 95% fits, then the last 5% probably fits too" is very intuitively easy to understand. It also took me to this page on wikipedia which seems almost made for the question I asked. So I think everyone else wondering the same thing I did will find it useful!

submitted by /u/Towerss
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Why don't freight trains use turbine engines?

Posted: 26 Sep 2017 03:15 PM PDT

Freight trains in the US use diesel-electric drive trains where the engines act as a generator that then drives electric motors. These trains are supposedly extremely efficient, with a commonly-cited figure of 400 mpg per ton.

However, I'm operating under the assumption that turbines are the most efficient way to produce electricity as they're used to produce electricity for the grid. If this is the case, then why aren't trains using turbines, since they're trying to turn fossil fuel into electricity at peak efficiency? If it's not, then why do power plants not use diesel?

submitted by /u/MrMannWood
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Do different isotopes (e.g. Carbon 12 and Carbon 14) have slightly different electron emission spectra?

Posted: 27 Sep 2017 02:53 AM PDT

Do isotopes of atoms cause the electrons to have slightly different energy levels and therefore slightly different emission spectra or do the electron levels remain the same?

submitted by /u/Moonkyled
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Would an impact on the moon during an eclipse allow us to do spectroscopy of the impact ejecta dust?

Posted: 27 Sep 2017 07:54 AM PDT

Could deorbiting a large spacecraft or meteor into the surface at a 90° angle to the Earth while the moon transits the sun allow us to do spectroscopy using the sun's light filtering through the dust cloud that results from the impact?

submitted by /u/brett6781
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Why do my eyes make a squeaking noise when I rub them roughly?

Posted: 26 Sep 2017 08:52 PM PDT

Why would a black hole with the mass of Jupiter trap light while Jupiter itself doesn't?

Posted: 27 Sep 2017 01:05 AM PDT

I'm a bit confused. One is a simple gas giant and the other a black hole of the same mass yet only the black hole traps light. Why is it that way?

submitted by /u/Pylon_Constructor
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Ask Anything Wednesday - Engineering, Mathematics, Computer Science

Posted: 27 Sep 2017 08:06 AM PDT

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Engineering, Mathematics, Computer Science

Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".

Asking Questions:

Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions.

The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.

Answering Questions:

Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience.

If you would like to become a member of the AskScience panel, please refer to the information provided here.

Past AskAnythingWednesday posts can be found here.

Ask away!

submitted by /u/AutoModerator
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When I reflected a laser off my phone screen, the reflection on the wall was many tiny dots in a grid like pattern, what is happening here?

Posted: 26 Sep 2017 08:27 PM PDT

Turbofan vs Gas Turbine?

Posted: 27 Sep 2017 02:45 AM PDT

I recently read about the Rolls-Royce MT30 gas turbines used in ships are based on Trent 800 turbofans with 80% part commonality. What are the mechanical differences between aircraft turbofans and Gas turbines and if none why the distinction in name from say a Turboshaft.

submitted by /u/C0RVUSC0RAX
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How would Earth's climate system respond to an increase in solar luminosity?

Posted: 26 Sep 2017 08:15 PM PDT

Could dark energy be used to harvest electricity using temperature differentials?

Posted: 26 Sep 2017 10:13 PM PDT

In a video I watched recently, it was theorized that empty space is not empty, but has a dark energy that is the reason for the expanding universe. Also mentioned was how that energy also gives empty space a radiant temperature. Sterling Engines run off temperature differentials, so if dark energy is a force that also creates heat, could it be harnessed to generate electricity? If not temperature differentials, are there better competing theories? (I'm intentionally ignoring the size such a system would need to be, and efficiency of the system, just asking if it's even feasible)

submitted by /u/halcyon918
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Why does Vancouver have two high tides per day?

Posted: 26 Sep 2017 09:59 PM PDT

I'm not exactly sure how I ended up looking at tide tables, but that's the internet for you. I noticed something that really surprised me: Vancouver BC has and extra high tide each cycle. As the tide is going out, it appears to change its mind and come back in a bit, before finally actually going out. Why?

Does it happen all year like this, or just some times?

I'm originally from Halifax, I didn't know about it being like that back there. Why is it different?

submitted by /u/djsunkid
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What would a sun spot look like if I were hovering directly above it?

Posted: 26 Sep 2017 09:50 PM PDT

Would it just be a giant black hole in the surface?

submitted by /u/willmcavoy
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Could someone explain what happens in this video? (And whether it is accurate)

Posted: 27 Sep 2017 05:16 AM PDT

If I was on a planet around a star between galaxies, would other stars be visible by the naked eye?

Posted: 26 Sep 2017 07:52 PM PDT

I've read there are only about 8,000 stars visible to the naked eye. I understand that there are some stars between galaxies that were ejected. If I was on a planet around a star in this area between galaxies, would there be stars observable with the naked eye or just the local sun?

submitted by /u/tailsfromretail
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How do colliding neutron stars create heavy elements above iron?

Posted: 26 Sep 2017 09:44 AM PDT

So im aware that supernova are the main source of our heavier elements. However neutron stars that collide also make them, my question is how.

Neutron stars no longer conduct fusion. So how does there act of colliding create heavy elements?

Does fusion restart by being fueled by shear gravity? Or is it another process.

If possible provide link to source.

Thank you

submitted by /u/WolfoftheNorth77
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How do warm blooded animals like rabbits survive a frigid winter?

Posted: 26 Sep 2017 04:27 PM PDT

Why don't highway tractors use electromotive diesel setups to pull freight similar to locomotive and mine haul?

Posted: 26 Sep 2017 08:53 AM PDT

Hello!

I'm not sure if this is the appropriate sub Reddit for this question, but hopefully there is an engineer kicking around that can shed some light.

I've worked in the trucking industry as a mechanic and I currently work as a mechanic for locomotives. I've always wondered why the trucking industry doesn't go the same way as locomotive and mine haul vehicles?

Diesel engines last longer when powering generators due to constancy of load and you no longer need a transmission, driveline and power-dividers. Also electric motors could be used to brake and they are very high torque.

Anyone have any experience in this subject?

Thanks!

submitted by /u/Tripydevin
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What is the cause behind the relationship between an atom being heavy and its propensity to decay?

Posted: 26 Sep 2017 09:00 PM PDT

Follow up: could we create an environment in which heavy elements that would normally decay remain stable?

submitted by /u/CraptainHammer
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How much energy does a tree consume in a day?

Posted: 26 Sep 2017 03:24 PM PDT

Hypothetically, there is an oak that is 80 ft tall, 24" diameter, and is 22,000 lbs (including roots). How much energy does that tree need from sunlight and nutrients in the soil on average to survive one day? I have read how much energy a tree can produce from being chopped down and wood burnt, but I haven't been about to find the energy it consumes in a day to live.

submitted by /u/Thomtits
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Why do electrons have kinetic energy?

Posted: 26 Sep 2017 05:55 PM PDT

The hydrogen atom consists of a negatively charged electron bound by a positively charged nucleus. Traditionally when we calculate the energy of the H atom we can partition the Hamiltonian into a kinetic energy part and a potential energy part. However when analyzing the ground state solution a cusp (singularity) appears at the position of nucleus since the potential energy goes to infinity. This cusp is "neutralized" by the kinetic energy which goes also to infinity at that point. Therefore it seems t that there is something fundamentally wrong with separating kinetic and potential energy at the quantum level. Can anybody with deeper quantum physics knowledge then me chime in?

submitted by /u/similus
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How do we determine how far away a distant galaxy is when the universe is expanding at an increasing rate?

Posted: 26 Sep 2017 01:58 PM PDT

The red shift given by a distant galaxy tells us how fast it was moving away from us a large number of years ago. But since the universe is expanding at an increasing rate, how do we determine how far away galaxies are?

submitted by /u/msief
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Does spacetime curve toward the event horizon nearest by or toward a central geometric point of the entire black hole?

Posted: 27 Sep 2017 12:59 AM PDT

Tuesday, September 26, 2017

What is a birth mark and why do so many people have them?

What is a birth mark and why do so many people have them?


What is a birth mark and why do so many people have them?

Posted: 25 Sep 2017 08:33 PM PDT

How can superconductors and superfluids be completely perfect?

Posted: 26 Sep 2017 03:58 AM PDT

So often in maths and physics we have to approximate the real world. Wires aren't perfect, they have some resistance; fluids have some viscosity but we assume zero friction... except when they don't.

Superconductors actually exist, and they have:

exactly zero electrical resistance

and certain isotopes of helium, when supercooled, flow without loss of kinetic energy.

How on earth is this possible? I'd understand negligible friction, or loss of energy, but precisely zero?

submitted by /u/sanguisuga635
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Why don't we have an exact number on the maximum mass of neutron stars?

Posted: 25 Sep 2017 07:17 PM PDT

A trail of reading wiki lead me to the page on the Tolman–Oppenheimer–Volkoff limit. It says the maximum is approximately 1.5-3.0 solar masses, which seems like a big window to me. One of the sources mentions composition and charge...but I thought neutron stars were uncharged and just made of, well, neutrons?

I imagine if the neutron star was spinning fast, centrifugal force would allow it to remain stable with a little more mass. Other than that, my instinct would be that calculating a maximum mass shouldn't be as complicated as it is.

submitted by /u/jammerjoint
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How does the hardware for quantum computers differ from classical computers?

Posted: 25 Sep 2017 06:26 PM PDT

Are they still largely silicon based or has the focus been on different materials?

submitted by /u/nottoodrunk
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Is there such thing as a "perfect whitebody"/reverse blackbody? i.e. something that absorbs and emits no thermal radiation at all

Posted: 25 Sep 2017 11:52 PM PDT

Is it possible for other planets with two stars to have star eclipses? Would the star get extra bright or would the star blocking the other star dim the light?

Posted: 25 Sep 2017 03:12 PM PDT

Why all satellites and space station orbit west to east and not north to south?

Posted: 26 Sep 2017 04:21 AM PDT

Can photons collide? What happens when we point two torches one at another?

Posted: 25 Sep 2017 12:39 PM PDT

When electrons give off energy to return to their ground state energy levels in the form of light (incandescence), where do the photons come from?

Posted: 25 Sep 2017 04:08 PM PDT

It's my understanding that the reason things visibly glow when heated is that the electrons have been excited to a higher energy level, and in order to return to their ground state energy level, they give off radiation, some of which is within the visible spectrum, causing the glow. Anyway, when electrons "give off" photons like this as visible light, where do the photons come from?

submitted by /u/danielj1632
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Why limit password length?

Posted: 26 Sep 2017 12:00 AM PDT

Heaps of banks do this. I don't see how it can provide any benefits.

submitted by /u/finlay422
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Why do trees shed their leaves and go dormant during fall?

Posted: 25 Sep 2017 04:25 PM PDT

In high school biology classes I've learned that photosynthesis is the process during which trees utilize CO2 and water to produce carbohydrates and oxygen, and the mechanism requires sunshine and chlorophyll.

There's some birch trees growing outside my house and for the past few years I've been observing that the onset of leaf shedding varies. Some years it's earlier in the season, late August-ish while other years it's later in the season, late September-ish.

I associate this with temperature, because some years I need warmer clothes earlier in the season and some years later.

However, according to the photosynthesis formula only water, co2 and sunshine are required so why don't trees keep photosynthesizing and grow during winter? Where in the plant would this temperature sensitivity be if not involved in the photosynthetic process?

submitted by /u/reekda56
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how can our ears tell us exactly the direction sound is coming from?

Posted: 25 Sep 2017 03:11 PM PDT

Are there any ways in which a lunar space station would be cheaper or have advantages over the ISS for science and research purposes?

Posted: 25 Sep 2017 11:23 PM PDT

How are studies on rat behaviour applicable on humans?

Posted: 25 Sep 2017 11:44 AM PDT

Rats brainsize is only a fraction of ours and I assume function very differently

submitted by /u/grappelz
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Do small "Cold Plasma" generators produce any harmful particles/ions/ozone?

Posted: 25 Sep 2017 10:38 AM PDT

I've come across such articles that state that small Plasma generators in certain Air Purifiers or AC units are very harmful to health.

However, most manufacturers nowadays have mid to high end devices that incorporate some sort of "PLASMA FILTERING" that uses "NEGATIVE IONS" to battle smoke, bacteria and dust or whatnot.

I have settled on an AC that has a small (~4 inches wide) cold plasma generator box shaped device in the inside mounted unit. So my question is can these small devices potentially be a health hazard in the home?

Does a cold plasma generator produce Ozone or Ions that can "survive" long enough to travel outside the unit and fill up the whole room and pose a health risk to people inhaling them? Does inhaling such negative ions and ozone particles cause health problems in the first place? And are these not particles that are supposed to exist in nature and aren't we already exposed to them?

submitted by /u/toshex
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Do we know how optical illusions affect animals? Can we learn about their sight that way?

Posted: 25 Sep 2017 11:13 AM PDT

Saw this gif and wondered...

submitted by /u/pando93
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In using directions in interstellar space, how are locations of objects tracked?

Posted: 25 Sep 2017 08:25 AM PDT

First, I figure there is some type of coordinate/grid system, so I am wondering about that and what we use as the x,y,z: (0,0,0) point of center for that system if we track objects in a three dimensional plane.

Second, how do we tell relative direction? For example, we use north, south, east and west on a theoretical plane (like on Earth) to tell direction, but in space, there is not only x and y axis, but z as well. Are there directions for this? Or would we just use up and down as the 3rd dimensional directions?

submitted by /u/icarustic
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Could Mars dust storms potentially contaminate category 5 areas off limits to the Category 4-B rated rovers?

Posted: 25 Sep 2017 05:42 PM PDT

I was thinking about this earlier today, and an earlier post on here prompted me to post. Basically, there are classifications for the cleanliness of spacecraft doing research looking for life on planetary bodies.

What I'm wondering is, although while the rovers (which are not rated clean enough to do research in potential water areas) are far away from water areas, could the global dust storms on mars potentially pick up microbes from the rovers, and transport them to the parts of mars that might have water?

Is this a problem that we have worried about?

submitted by /u/petlahk
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Monday, September 25, 2017

Nutrition Facts: Why is sodium listed instead of salt?

Nutrition Facts: Why is sodium listed instead of salt?


Nutrition Facts: Why is sodium listed instead of salt?

Posted: 24 Sep 2017 02:58 PM PDT

On nutrition facts they always list off sodium but never just salt. How come chloride content isn't listed as well, or all of the elements for that matter?

submitted by /u/Khannuuuuur
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When a baby is in the womb, what is the biological signal that lets the mother know the baby has reached full development, and what goes wrong with this signal when a child is born premature or late?

Posted: 25 Sep 2017 04:44 AM PDT

Is there just a biological clock in the mother's body that says 'times up' and then gives birth regardless of development, or is the signal sent from the unborn baby when they're fully developed?

submitted by /u/Mvnz
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The heart is just a basic two way pump. Why can't we just install two turbines and have a continuous flow of blood?

Posted: 25 Sep 2017 05:28 AM PDT

How do they determine the impact of a volcano that's about to erupt?

Posted: 25 Sep 2017 05:06 AM PDT

For example the one on Bali. How do they know that a radius of 12km will be enough?

submitted by /u/martijnvb
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What is the process of finding, extracting and containing helium for sale?

Posted: 25 Sep 2017 05:06 AM PDT

Considering that quantum computers may become a reality, how this will affect to programming languages?

Posted: 25 Sep 2017 07:06 AM PDT

I come to read this thread and I'm wondering if this could affect to programming languages such as C++, and then our ways to write software, or if it just would have and impact at the hardware level and/or assembly languages (like ARM).

submitted by /u/EuGENE87
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What gas is inside of unopened peppers? Or is it just air?

Posted: 24 Sep 2017 01:42 PM PDT

I'm assuming as a pepper grows its inside is never exposed to air on the outside.

submitted by /u/Driftinfisch
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How heavy is fire? If something catches on fire is it heavier or lighter?

Posted: 24 Sep 2017 07:06 PM PDT

How do we know how long the sun will burn for?

Posted: 25 Sep 2017 05:49 AM PDT

What would a circle look like if the ratio of its circumference to diameter was 3 instead of pi?

Posted: 24 Sep 2017 10:07 PM PDT

In Arthur C Clarke's series A Time Odyssey, there are spheres that have the ratio as 3 instead of pi and I was wondering what they might look like.

submitted by /u/747173
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What is a kilowatt hour, and why do electric companies charge based on this instead of kilowatts?

Posted: 24 Sep 2017 11:40 PM PDT

why are there Northern Lights but not Eastern Lights?

Posted: 25 Sep 2017 05:34 AM PDT

Is it because there is less rotation at the north and south pole's so the effect is condensed?

submitted by /u/detspek
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How does deodorant work?

Posted: 24 Sep 2017 01:44 PM PDT

I sweat a lot, but I never smell from it. How?

submitted by /u/puffymustash
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How much Asteroid mining/extra mass until it has an impact on earth's orbit?

Posted: 24 Sep 2017 04:41 PM PDT

How do scientists figure out how tall a mountain is?

Posted: 24 Sep 2017 08:49 PM PDT

How does a volume knob work?

Posted: 24 Sep 2017 10:36 PM PDT

If fluorine is bound into a diatomic molecule in which the octet rule is satisfied, then why is it still unstable to the point in which it violently reacts with just about anything else?

Posted: 24 Sep 2017 10:25 PM PDT

I have always been under the impression that in molecules in which the octet rule has been satisfied, each atom is "happy" with the eight electrons in its outer shell. Why, then, does fluorine prefer to bond with, say, sodium as opposed to itself? Why do hydrogen and oxygen prefer to be bound into H2O as opposed to their diatomic counterparts? In essence, why do atoms prefer some arrangements to others, even though the octet rule is fulfilled either way?

submitted by /u/Forestpotato
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In a magnetic hard disk, how are the servos that position the read/write head so accurate?

Posted: 24 Sep 2017 09:50 PM PDT

With the data tracks as narrow as they are (on the order of a hundred nanometers or so wide), these servos must be incredibly precise. How do they achieve that level of precision?

submitted by /u/dzScritches
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Why is drinking milk after spicy foods better than drinking water?

Posted: 24 Sep 2017 01:37 PM PDT

Google said that milk is non-polar which help to actually dissolve the capsaicin molecules in your mouth but I don't understand that.

submitted by /u/Theblankuser
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If we want to colonise mars, why don't we colonise it first with Cyanobacteria and then plants in order to create a habitable atmosphere?

Posted: 24 Sep 2017 02:40 PM PDT

In sending humans to Mars, what problems will need to be solved with respect to launching and returning astronauts from Mars' surface?

Posted: 24 Sep 2017 01:53 PM PDT

Even with the lower Martian gravity, will returning launch platforms/vehicles need to be in place before humans step foot on Mars for the first time? Also, with respect to the amount of time to travel to Mars and the differences between a Martian orbit and and Earth orbit, what is the minimum amount of time such a trip require?

submitted by /u/arachnids-on-parade
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