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Thursday, March 22, 2018

What makes some materials like cat fur or velvet feel soft?

What makes some materials like cat fur or velvet feel soft?

What makes some materials like cat fur or velvet feel soft?

Posted: 21 Mar 2018 10:12 AM PDT

If the universe is expanding, what is it taking the place of?

Posted: 21 Mar 2018 08:16 PM PDT

I'm having a hard time wrapping my head around the concept of an ever-expanding universe. If the volume of the universe is increasing, then what is outside of it? Where can the edges of the universe go if there is nothing on the other side? Also isn't space just nothing? How can nothing expand? And if there's nothing on the other side of space then how do we differentiate that nothing from the nothing that is our space?

submitted by /u/chinchillada
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Why do "cold" and "wet" textures feel so similar?

Posted: 21 Mar 2018 08:28 AM PDT

Edit: thanks to the numerous commentors giving input on this question!

submitted by /u/octopusgreenhouse
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Why do most medicinal pills have "-HCl" added to the end?

Posted: 21 Mar 2018 08:34 AM PDT

How does Uranium Lead dating of crystals work?

Posted: 22 Mar 2018 04:28 AM PDT

Just watching Cosmos. It's the episode about finding the age of the earth. They explain that uranium decays to lead. We know the half life of lead. So if we measure the amount of lead and the amount of uranium, we can do some maths to find the age of a sample.

So far so good. But then they say that the original readings for lead were too high. But how could they know that?

Wouldn't the high readings for lead just mean that the age calculated would appear to be much higher?

How do we know the acceptable range for the values for lead? Any help would be gratefully received.

submitted by /u/fizdup
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Why do electron holes move 2x slower than electrons?

Posted: 21 Mar 2018 07:08 PM PDT

Electron holes are just places in the lattice where electrons aren't present, so why is the carrier mobility around 2-3x less for electron holes compared to electrons? I never quite understood why.

It obviously has massive effects in electronic design like VLSI gates and power electronics.

submitted by /u/mech_eng_lewis
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How do we know what the full milky way looks like?

Posted: 21 Mar 2018 07:19 PM PDT

Plants know which way to grow because of gravity , so what happens if we plant one in space ?

Posted: 21 Mar 2018 03:42 PM PDT

Do roots grow in all directions , or do they grow in a random direction which could make the plant grow in the ground , and the root going upward ( I consider upward is out of earth)

submitted by /u/appophiss
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Do blind people see visuals on psychedelics?

Posted: 21 Mar 2018 07:19 AM PDT

So if Lightbulbs are based on heating metal so that it gets excited and emits photons. Is the type of metal the difference between the type of photons? ex. xray vs regular light, or is it something like tungeston can emit any photon depending on weird stuff like heat and vaccum levels?

Posted: 22 Mar 2018 03:16 AM PDT

What effectively renders a volcano inactive?

Posted: 21 Mar 2018 08:23 PM PDT

Is there such thing as a double Gamma function similar to the Double Factorial?

Posted: 21 Mar 2018 01:25 PM PDT

After watching blackpenredpen's latest video I was motivated to try to derive an analytic function for double gamma that would extend the double factorial to non-integer numbers.
I came up with the following: (i don't see this in the wikipedia article

Define the Double Gamma Function Γ² (x)=( 2^((x-1)/2) *Γ((x+1)/2)*sin²(π/2* x) + 2^(1-x/2)*Γ(x)/Γ(x/2)*cos²(π/2* x) ) / √( 1+k*sin²(πx) ) where k~0.0127996745295915

This has all the properties we want of the double factorial including:
- Γ²(n+1)=n‼; (Double Gamma equals Double Factorial for integer values of n)
- Γ²(x+1)Γ²(x)=Γ(x+1); (same relationship as double factorial, n‼(n-1)!!=n!)
- expand double factorial to all real numbers except on the poles that are located at the negative even integers
- Γ²(0+1)=1; so 0!! = 1

Here are values of x, Γ²(x+1) and Γ²(x+1)*Γ²(x)=Γ(x+1) for 0 to 7 incrementing by 0.5

x Γ²(x+1) Γ²(x+1)*Γ²(x)=Γ(x+1)
0 1 1
0.5 0.9628 0.8862
1 1 1
1.5 1.3806 1.3293
2 2 2
2.5 2.4070 3.3233
3 3 6
3.5 4.8323 11.631
4 8 24
4.5 10.831 52.342
5 15 120
5.5 26.577 287.88
6 48 720
6.5 70.406 1871.2
7 105 5040
submitted by /u/Earthbjorn
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Do animals forget about their offspring over time?

Posted: 21 Mar 2018 02:10 PM PDT

Is there a scientific explanation for why children and even adults are so preoccupied with ‘fair’?

Posted: 21 Mar 2018 07:14 AM PDT

I'm a teacher, and children seem to spend such a huge chunk of their time concerning themselves with other kids' affairs and whether the distribution of reward/punishment/attention is fair. Is this just in the way we raise kids or is there something more complex at work?

submitted by /u/Lettuce-b-lovely
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I run a current through a solenoid and get a magnetic force. I stick an iron core in the solenoid and get a bigger magnetic force. How is conservation of energy preserved?

Posted: 21 Mar 2018 02:11 PM PDT

Are drought prone regions more vulnerable to wars and conflicts?

Posted: 21 Mar 2018 07:18 AM PDT

How and When does fetus/infant/toddler get its guts colonized by "good" bacteria?

Posted: 21 Mar 2018 05:34 AM PDT

Does it happen before the birth? Or the bacteria come with mother's milk or later (external food)? How the initial 'colonization' happens? How kid's organism assures that these will be the "good" bacteria?

submitted by /u/dge278
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how do you prove that 1+1=2?

Posted: 21 Mar 2018 03:05 PM PDT

in principia mathematica there are well over 100 pages explaining this, how exactly do you go on to explain 1+1=2 using hundreds of pages?

submitted by /u/MLPorsche
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What makes something smell “bad”?

Posted: 21 Mar 2018 09:14 AM PDT

How much more do we know about the 'ocean waves' on Titan?

Posted: 21 Mar 2018 05:13 PM PDT

Why do some Con trails(the clouds planes leave behind) last much longer than others?

Posted: 21 Mar 2018 04:57 PM PDT

I live just a few miles from Tampa airport(TIA). Sometimes the trails last forever, but most times they go away quick. What causes it to to linger. Its like it's making it own cloud.

submitted by /u/Tommy4uf
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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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