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Wednesday, March 21, 2018

How do seeds know which way to grow?

How do seeds know which way to grow?

How do seeds know which way to grow?

Posted: 20 Mar 2018 05:00 PM PDT

Does epigenetics play a role in speciation?

Posted: 21 Mar 2018 06:57 AM PDT

I was thinking about how similar neanderthal and our DNA is, and wondered if there were more stark epigenetic differences between us that could explain some of the reduced viability of hybrid offspring.

In any case, it got me wondering if, in general, epigenetic changes like DNA methylation were in part responsible for reproductive isolation and the beginnings of speciation, i.e. differential methylation that gives positive fitness for two different groups in the same species but negative fitness when hybridized could result in less successful crossing between the groups.

I found a paper that I think supports this idea, but I'm not an expert in this field and also don't know how much of an outlier this paper is. Also, even if this happens, I don't know how common it is or how big a role it is thought to play in speciation.

submitted by /u/alphaMHC
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Why does South Africa have so many minerals?

Posted: 20 Mar 2018 10:10 AM PDT

I'm taking an intro to geology course on minerals/gems and there seems to be like everything in South Africa: PGE's, diamonds etc. What is it about RSA's location(?) that makes it so mineral rich?

submitted by /u/spacemonkey1990
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With all the advantages Solar Sails have over Fuel, why aren’t they being utilized more?

Posted: 20 Mar 2018 12:25 PM PDT

Do any scientific methods exist to detect old river courses and water paths?

Posted: 20 Mar 2018 10:45 AM PDT

Please elaborate on any methods(if they exist) to detect/predict river networks of olden civilizations (5000 years old).

submitted by /u/lachaar
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How does the checkbox captcha work?

Posted: 20 Mar 2018 08:47 AM PDT

Why do we use lasers instead of electron beams for data storage in things like cds/dvds?

Posted: 21 Mar 2018 05:57 AM PDT

I know that the wavelength of electrons is considerably smaller than that of visible light, which is why it is used for electron microscopy. Wouldn't the smaller wavelength mean that it could be used for higher-density storage than visible light? Why have I not heard of a an electron beam based storage device?

submitted by /u/itijara
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How are unknown chemicals identified?

Posted: 20 Mar 2018 08:56 PM PDT

As you may have heard, Russian president Vladimir Putin is once again projecting aggression to the world by murdering another ex spy in Britain with a chemical weapon.

The OPCW has stated it will take 2-3 weeks to identifythe chemical used in the attack. However, the British government was able to identify the chemical and where it came from just hours after the attack happened.

How are these chemicals identified? And why does the OPCW, the international body set up to do this exact task, not use the same advanced equipment that the British government to do their job in a fraction of the time?

submitted by /u/P0iS0N0USFR0G
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What is the smallest theoretical size a transistor could be?

Posted: 21 Mar 2018 05:39 AM PDT

I'm an electronics technician, so I wonder: how many atoms wide could we make computer transistors? It has to be larger than one to allow for doping of the junctions.

submitted by /u/crazywalt77
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What would the discovery of magnetic mono-poles mean mean for Maxwell's equations?

Posted: 20 Mar 2018 09:07 PM PDT

My understanding is that Maxwell's equations don't support the existence of magnetic mono-poles as they are (magnetic flux through closed surface is always 0). Could the laws be rewritten to describe mono-poles or would the discovery of such magnets change our understanding of EM completely?

submitted by /u/bfiffer
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What determines a sapphire color?

Posted: 20 Mar 2018 02:21 PM PDT

Is there any way to physically discover if a person has siblings by examining their anatomy, genetics, or any other experiment?

Posted: 20 Mar 2018 02:16 PM PDT

Obviously doesn't include asking the person :P Any other experiment could include some test of electromagnetic waves or wave response from some part of their body etc..

submitted by /u/hypumji
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Do animals suffer from motion sickness?

Posted: 20 Mar 2018 02:05 PM PDT

How do compiling errors get their messages?

Posted: 20 Mar 2018 03:24 PM PDT

When compiling a program in an IDE, how does it know where the error is and what went wrong? Does it use regex to look for common errors or something along those lines?

submitted by /u/SnicketBottom
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Did the potato mutate into the sweet potato or the sweet potato mutated into the potato? Or do they come from different spices?

Posted: 20 Mar 2018 09:01 AM PDT

What are some of the Eastern Gray Squirrel behavior and mannerisms?

Posted: 20 Mar 2018 03:26 PM PDT

There is a male squirrel (and sometimes a female) that I often see outside my window and for some reasons I love watching their behaviour and personality. I was wondering if anyone could give me some more info on there behaviour. I have watched and researched about them a bit but I was wondering if anyone could provide me with more detailed information such as their mannerisms and suddler behaviours or even some good artical about them.

submitted by /u/dre224
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Why do so many human tribes practice such painful rituals? (E.g. tattooing, piercing, scarification, bullet ants)

Posted: 20 Mar 2018 02:32 AM PDT

How are programming languages built?

Posted: 20 Mar 2018 10:49 AM PDT

How could I determine where the darkest area on a planet, that is tidally locked to a gas giant would be?

Posted: 20 Mar 2018 06:01 AM PDT

I am Trying to write a story that takes place on a planet that is tidally locked to a gas giant. My idea requires an area on the planet that is darker for longer then the other areas. Is there a way to determine where the darkest area of this planet would be, taking into account reflected light from the gas giant, as well as the sun?

submitted by /u/nuclearstroodle
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Tuesday, March 20, 2018

How significant is the genetic difference between the Northern and the Southern White Rhino?

How significant is the genetic difference between the Northern and the Southern White Rhino?

How significant is the genetic difference between the Northern and the Southern White Rhino?

Posted: 20 Mar 2018 03:19 AM PDT

With the last male Northern White Rhino dying today, and only two females left, chances for survival of the northern 'half' of this species is pretty much 0. Apperently they have enough sperm to keep the two remaining ladies getting pregnant, but it is not that straight forward of course.

To my surprise however, I read that there are thousands of their Southern counterparts left. I don't have a clue about the differences between the two though. Although the reasons they are still around might be really interesting, I am more interested in the biological difference between north and south. Could 'we' rejuvinate the northern species by using their southern brethren? How different are they?

submitted by /u/Thoarxius
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Do current carrying wires also create electric fields or only magnetic fields?

Posted: 20 Mar 2018 05:41 AM PDT

My textbook is rather unclear about this. Much obliged for any answers :)!

  1. Does the net charge density change in a wire in a laboratory frame as current is applied to it?
  2. Will it become electro-statically charged?
  3. And does it therefore generate an electric field?
  4. Or are only magnetic fields generated following the Ampère's right-hand grip/corkscrew rule?
submitted by /u/AlwaysUnite
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How does France get rid of nuclear waste from more than 60 nuclear power plants?

Posted: 19 Mar 2018 12:05 PM PDT

How did cells survive without a mitochondria?

Posted: 20 Mar 2018 02:24 AM PDT

There is a theory that the mitochondria was its own cell before being incorporated with another cell. If this theory is true how did the cells survive without a mitochondria?

submitted by /u/Rogocraft
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How do migrating species determine when it is time to migrate?

Posted: 19 Mar 2018 04:36 PM PDT

How many light years across is the sun’s magnetic field?

Posted: 19 Mar 2018 01:53 PM PDT

Since humans are drilling so much oil out of the ground, are there large empty caverns underground where the oil used to be?

Posted: 19 Mar 2018 09:17 AM PDT

Humanity has drilled a lot of oil since the late 1800's. What happens to all the empty space where the oil used to be? Is it just empty air pockets now or does it fill in with dirt?

submitted by /u/AvailableWrongdoer
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What would happen if someone not suffering from mental illness were to take a schizophrenic's drugs?

Posted: 19 Mar 2018 12:40 PM PDT

Does Quantum Field Theory rely upon one particular interpretation of quantum mechanics?

Posted: 19 Mar 2018 06:07 PM PDT

Is QFT an interpretation in and of itself? Is it contingent on one particular interpretation? Or can it be coupled with any interpretation, from many worlds to pilot waves to the Copenhagen?

submitted by /u/Jnicky69
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How energy intensive it is to generate gamma rays for sterilization?

Posted: 19 Mar 2018 02:35 PM PDT

I have heard that one of the ways to very efficiently use and dispose of bio-solids, is to use them as fertilizers, problem is, you have to disinfect it, and using anti-biotics would be a horridly bad idea.

Could maybe gamma rays used to sterilize it for good? Would it be too cost intensive?

submitted by /u/Doveen
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Why does the "bridge ice before road"?

Posted: 19 Mar 2018 05:00 PM PDT

Is this due to construction materials, elevation, what else possibly?

submitted by /u/DarkLunch
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Where do volcanic gas clouds rise from?

Posted: 19 Mar 2018 03:12 PM PDT

Does the gas just leave through small cracks or is there so sort of hole at the top of every volcano? If the volcano never steams is that when it erupts? Why does it steam at all?

submitted by /u/trouter2
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Is radioactivity a requirement for an element to be fissile?

Posted: 19 Mar 2018 08:08 PM PDT

I'm trying to understand some things about nuclear reactions. Radioactive elements fission spontaneously, whereas fissile elements can fission through the introduction of a low energy neutron. But are all fissile elements automatically radioactive? Is it possible for a large enough atom to fission easily without decaying on its own?

submitted by /u/LexHalycor
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How do all the zillions of cell phones and other types of transmitters not interfere with one another?

Posted: 19 Mar 2018 10:50 AM PDT

What happens when proton collides with an atom?

Posted: 19 Mar 2018 01:22 PM PDT

What happens to the energy of the proton? It is absorbed? If yes, fully or partially?

it's not necessary to explain. a few links that can clarify things would be good enough.

submitted by /u/Phayzeee
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Does epigenetics have implications for horticultural/agricultural seeds?

Posted: 19 Mar 2018 06:17 PM PDT

I thinking of this as I was saving seeds from my heirloom tomato harvest - would seeds from a plant that faced drought produce a different offspring than one that didn't?

What about seed storage conditions?

submitted by /u/kuhewa
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Why do each booster from the Falcon Heavy cause 3 sonic booms?

Posted: 19 Mar 2018 02:12 PM PDT

My understanding of sonic booms are limited. After watching (are more specifically listening to) the falcon boosters landing, there was clearly 3 definitive booms per booster. My question is why are there 3?

submitted by /u/Wattsits
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How do birds detect magnetic fields to know which way is north and south?

Posted: 19 Mar 2018 06:45 AM PDT

Why where the alpha particles expected to pass straight through the plum pudding model?

Posted: 19 Mar 2018 04:01 PM PDT

Everytime I've heard about this experiment, right from grade 5 upto my analytical mechanics exam today, they say how the alpha particles were expected to pass straight through the foil but not all did. And then using Binet's equation and central potential we derive the neuclus model of the atom.

But absolutely no one has ever explained why can't the same be explained through plum pudding model? Even if electons were embedded into a positively charge pudding, one can derive the same central potential equations assuming atoms are rigid and nothing can pass through them; which they should be because it was called the "Plum pudding model" not the "Corn soup model"

submitted by /u/arnavbarbaad
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Why is icing a 'sports' injury generally the first recommended go-to treatment and how does it promote healing?

Posted: 19 Mar 2018 11:20 AM PDT

As a lay person, rest and elevation make intuitive sense for a sprained ankle or whatnot, but icing seems weird. Like if you're not a professional athlete who needs to prioritize regaining mobility, why not let the injury swell, wouldn't an increased blood flow to the injury be helpful?

submitted by /u/Nurgle
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Monday, March 19, 2018

How do people colorize old photos?

How do people colorize old photos?

How do people colorize old photos?

Posted: 18 Mar 2018 11:55 PM PDT

I saw a post about someone colorizing a black and white picture and I realized I've not thought on this until now. It has left me positively stumped. Baffled if you will.

submitted by /u/PadstaE
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Are our bones sensitive to cold just like our teeth are?

Posted: 18 Mar 2018 01:43 PM PDT

Did matriarchies ever exist? If so, did they extend beyond the immediate tribe? What is the consensus in the anthropological community?

Posted: 18 Mar 2018 07:03 PM PDT

Have any megafauna specimens besides the mammoth been recovered from the Arctic? Any similar discoveries in the Antarctic.

Posted: 18 Mar 2018 06:22 PM PDT

I recall mentions of mega-viruses and fears of dormant microbial pathogens being revived. But oddly enough, no other (extinct) megafauna remains have made any headlines, at least not recently. In particular, it would be awesome if an auroch or two, in sufficiently good condition to provide genetic material, could be used to help the various de-extinction efforts underway. But I'll settle for any frozen corpse as long as its not another mammoth.

submitted by /u/StardustSapien
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Is a geostationary orbit above a place other than the equator possible?

Posted: 19 Mar 2018 03:57 AM PDT

Say you want a sattellite in geostationary orbit above your own house, is that possible?

submitted by /u/CoRe0412
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From the book E=mc2 and why should we care (Brian Cox and Jeff Forshaw). Why do they state that there are only two possibilities for measuring distance in spacetime and where does the act of flipping the sign in Pythagoras arise from?

Posted: 19 Mar 2018 03:48 AM PDT

Here is the text from the book(slightly abridged).

"We now have time and distance intervals in the same currency. For example, they could both be given in meters, or miles or light-years or whatever. Figure  illustrates two events in spacetime, denoted by little crosses. The bottom line is that we want a rule for figuring out how far apart the two events are in spacetime. Looking at the figure, we want to know the length of the hypotenuse given the lengths of the other two sides. To be a little more precise, we shall label the length of the base of the triangle as x while the height is ct. It means that the two events are a distance x apart in space and a distance ct apart in time. Our goal, then, is to answer the question "what is the hypotenuse, s, in terms of x and ct?" Making contact with our ear- lier example x = 10 meters is the distance in space from bed to kitchen table, and t = 1 hour is the distance in time. So far, since c was arbitrary, ct can be anything and we appear to be treading water. We shall press onward nonetheless. We have to decide on a means of measuring the length of the hypotenuse, the distance between two events in spacetime. Should we choose Euclidean space, in which case we can use Pythagoras' theorem, or something more complicated? Perhaps our space should be curved like the surface of the earth, or maybe some other more complicated shape. There are in fact an infinite number of ways that we might imagine calculating distances..........In our case, the simplest way to construct a distance is to assume that at least the space part of our spacetime should be Euclidean; in other words, space is flat. This means that the familiar way of working out the distance in space be- tween objects in the room in which we are seated reading this book is carried over into our new framework intact. What could be simpler? The question, then, is how we should add time. Another simplifying assumption is that our spacetime is unchanging and the same everywhere........these two simplifying assumptions, we are left with only two possible choices as to how to calculate distances in spacetime. The length of the hypotenuse must be either s2 = (ct)2 + x2 or s2 = (ct)2 - x2. There is no other option. Although we did not prove it, our assumption that spacetime should be unchanging and the same everywhere leads to only these two possibilities and we must pick either the plus sign or the minus sign."

submitted by /u/tehbagend
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Why do people with dementia experience hallucinations? In particular, why do the vast majority experience seeing children?

Posted: 19 Mar 2018 01:55 AM PDT

My grandmother has dementia and whenever I visit her she talks about seeing children in the room with us.

I'm particularly interested in this phenomena because she is blind.

submitted by /u/ZhenHen
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What are the main complications stopping us from having supercapacitors?

Posted: 19 Mar 2018 02:06 AM PDT

Since mountains are changing elevation due to plate tectonics is it possible to know what the highest mountain to ever have existed was?

Posted: 18 Mar 2018 12:31 PM PDT

For example the Appalachians are older then the Rockies and I've been told that at some point in history they were taller. Is it possible that the tallest mountain on earth was at one time in that mountain chain and if so is it possible for us to know what they highest peak ever was?

submitted by /u/airportlayovers
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Why do we use pillows now when we sleep? Did we need this during the prehistoric/ancient age? What changed?

Posted: 19 Mar 2018 08:27 AM PDT

If weather storms are due to air moving from high to low pressure areas until there's equilibrium, how come the storms on Jupiter last continuously for centuries?

Posted: 18 Mar 2018 11:10 PM PDT

What are the biggest efforts against climate change?

Posted: 19 Mar 2018 07:31 AM PDT

Is there any particular reason for the number of states of matter being what it is? Could we have an arbitrary number of states between those?

Posted: 19 Mar 2018 06:29 AM PDT

I'm not really worried about plasma or BEC here, since I don't know much about these. Also, I know the question sounds a bit speculative, but I'm not really interested in what another state of matter would be like, I just mention it for discussion purposes.

So, from Gibbs' phase rule we know that we can have, at best, three phases at equilibrium for a single component. Of course, this makes the solid/liquid/gas partition at triple point feel natural, since we can't have a fourth state there.

However, combinations such as solid I + solid II + liquid are possible and define a triple point also, so what is stopping nature from having something like solid + arbitrary intermediate phase + liquid, where the intermediate is an imaginary, whole different state of matter?

I mean, although solid I and II are both different phases, they are both solid, so it seems the phase rule can't "know" that the three states are meaningful or special. Is there something limiting the number of states of matter? Or is it a case of "well, that's what we have, I guess"?

submitted by /u/von_Monte_Cristo
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Is there a major difference between steam and fog? At a basic understanding, they’re both just water in a gaseous state right?

Posted: 18 Mar 2018 11:53 AM PDT

Why do we stop feeling hungry when we're nauseous?

Posted: 18 Mar 2018 04:43 PM PDT

I currently have some sort of stomach bug and I've been having diarrhea all day (TMI, sorry). All I've eaten today is a granola bar (and about half a bottle of powerade) and I don't feel hungry at all. I am just curious what's going on in my body - are the mechanoreceptors in my stomach cells somehow less sensitive? Are the signals trying to tell me that I'm hungry being interrupted? Is my immune response telling my body that I shouldn't eat or I'll throw up? If so, how?

TL;DR: How does being sick affect the body's ability to process information that might ordinarily tell me I should eat?

submitted by /u/thefool_thegrass
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What file format is the images and info that went along with the Voyager spacecrafts on the golden records in?

Posted: 19 Mar 2018 04:05 AM PDT

Are there instructions on how to read the records?

submitted by /u/00Jim
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What's the importance of rocket engine exhaust gas velocity in terms of forces acting on the nozzle?

Posted: 19 Mar 2018 03:42 AM PDT

I try to understand thrust of a rocket engine in terms of unbalanced forces ONLY (so please do not use Newton's 3rd law for explanation. I do understand it, however IMO it doesn't explain thrust, it just shows a relation between physical quantities). While I understand forces acting on a combustion chamber and a nozzle, I can't understand why exhaust gas velocity is so important. What's more confusing to me is that with increase of gas velocity in the diverging section of a nozzle the pressure drops. Wouldn't one want to have high pressure to get some additional pushing force?

submitted by /u/Angel-0a
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In cars, why do objects in the side mirror opposite the driver appear so much farther away?

Posted: 18 Mar 2018 04:00 PM PDT

What makes a material sticky?

Posted: 18 Mar 2018 08:05 AM PDT

Why does AM radio play with such lower quality compared to FM?

Posted: 18 Mar 2018 01:16 PM PDT

I've always noticed that between AM and FM radio, AM's sound has always been more scratchy and unclear than FM. Does anyone know why this is?

submitted by /u/qui505092
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