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Saturday, July 29, 2017

Why is the human nose the shape it is? Why isn't it just two holes in our face?

Why is the human nose the shape it is? Why isn't it just two holes in our face?

Why is the human nose the shape it is? Why isn't it just two holes in our face?

Posted: 29 Jul 2017 03:59 AM PDT

How high could mountains on Earth grow? Is there evidence of higher mountains in the past?

Posted: 29 Jul 2017 04:55 AM PDT

Given what we know about plate tectonics, erosion and so on, is there a maximum height mountains could grow to?

Could a range like the Himalayas reach 5-10km higher in time and do we have any evidence of this in the past?

submitted by /u/trendyhipsterboi
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I saw a picture claiming that manhole covers are round because a circle is the only shape that can't be made pass through itself. Is it true?

Posted: 29 Jul 2017 03:11 AM PDT

I saw a picture on cracked.com claiming what I described in the title.

I wonder, is it really true?

submitted by /u/DaBeechees
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If I donate blood, then later need a blood transfusion, what are the odds that I'm receiving my own blood?

Posted: 29 Jul 2017 04:20 AM PDT

Why doesn't aluminum seem to glow orange when hot like other metals?

Posted: 29 Jul 2017 04:07 AM PDT

What produces the whistling sound you hear when a large bomb is being dropped or a firework is going off, etc?

Posted: 28 Jul 2017 05:54 PM PDT

Could someone please explain to me why quantum entanglement occurs?

Posted: 28 Jul 2017 11:16 PM PDT

From my understanding of quantum entanglement (it might be wrong) an electron in a pair will tell you information about the other electron in the pair regardless of the distance between them. Also manipulating one electron will affect the other paired electron. If all electron are exactly the same shouldn't one not affect another specific electron. Also when you manipulate electron does the the other electron get affected instantaneously or does it somehow have to communicate with the other electron. If so how fast do they communicate with each other and how do they do it.

submitted by /u/mapzv
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How does nucleation of crystals happen microscopically?

Posted: 29 Jul 2017 02:58 AM PDT

I am trying to purify a rather large batch of Rochelle salt by recrystallization.

I have observed some weird things concerning the nucleation of crystals, and as I want to grow one big single crystal, I want to minimize nucleations.

So my question is as the title says, what happens microscopically during nucleation of crystals?
And how exactly does it explain the following four points:

1) I used an clean old glass oven dish with a lot of scratches with my first batch. Even though there were a lot of scratches only 6 big crystals formed. Why didn't all the scratches form crystals (see also (3))

2) I got one crystal out with a toothpick. The next day, everywhere my toothpick touched the glass small crystals were growing. (I have seen a similar effect with escaping airbubbles in nearly boiling water after stirring with a spoon) How does a wooden toothpick alter the glass surface in such a way that crystals are nucleated wherever it contacted the surface?

3) After the first batch, while resupersaturating a new batch, I cleaned the oven dish with tap water, I dried it with a towel, and rinced it three times with distilled water. (first time I didn't dry it with a towel, I just rinced the dish) The next day the entire bottom of the dish was covered with a layer of small crystals strongly adhered to the bottom of the plate. How did the towel change the glass surface? Probably similar to (1)

4) Since that crystal layer was difficult to remove from the glass, my third batch was in big flexible tupperware(clone) pot. Also with plenty of scratches. Similarly to (1) there were a few big crystals growing.

5) Is there a procedure that minimizes nucleation in general? I want to grow a single, flat crystal with a specific crystal plane pointing upwards on a plane of glass. How can i be sure that I have replicated situation (1) so that I don't have to worry too much about random nuclations spoiling my big crystal?

Thanks!

submitted by /u/Soldersponge
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Do all animal species have reproductive cells with flagella?

Posted: 28 Jul 2017 09:16 AM PDT

How much energy does it take to make an average LED indicator blink?

Posted: 28 Jul 2017 03:25 PM PDT

What sends the original signal in logic gates?

Posted: 28 Jul 2017 04:46 PM PDT

So I was learning about logic gates and how when electrons can flow through it is true (or 1) and when they can't it is 0. now my question is what is the stimulus that makes this logic gates do it and where does it come from? e.g I want true so how does my computer know to send something to the logic gate to allow electrons to flow through and make it true? EDIT: in other words I know transistors are the ones that send true or false, but what sends the signal to them?

submitted by /u/johnlavolpe
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When you double the speed of a sound recording, the pitch doubles. When you double the speed of a video recording, why doesn't the light frequency double?

Posted: 28 Jul 2017 08:06 AM PDT

I got asked this by a student and I'm struggling to put forward a sensible explanation - it feels like it should be obvious, but for the life of me I can't put it into words.

If you play back a 48k audio sample at 96k, then the frequencies double, the length of the sample halves, and the perceived pitch is double. Easy.

If you play back a 30fps video clip at 60fps, then..., well the length of the video clip halves, but it looks the same. Reds are reds, blues are blues. The perceived light "pitch" hasn't changed. Why not? Where's the blueshift?

I'm getting annoyed with myself for not being able to give a sensible explanation. Help! I'm ready to facepalm, please point out the obvious to me :-)

submitted by /u/betamat
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In an X-ray tube, what exactly causes X-rays to be generated from the target? I understand a lot of the energy ends up being heat but what exactly causes the X-rays to be produced?

Posted: 28 Jul 2017 04:01 PM PDT

How does changing the position and/or angle of a laser source affect how the beam travels through a converging lens?

Posted: 28 Jul 2017 04:00 PM PDT

If I point a laser beam anywhere at a converging lens, will the beam always be redirected and reach (a line running through) the center of the lens after it has travelled the focal length of the lens?

For example, this question entails both deviation from the center of the lens, pointing the laser at an angle not perpendicular to the lens, and a combination of both.

Thanks!

submitted by /u/markmcckkenzie
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Why is there a reflective ripple on the pavement of the road when looking at it from a distance(noticeable when driving a car)?

Posted: 28 Jul 2017 07:04 PM PDT

Whenever I'm driving I can see the tires of the car reflected in the road as like almost silvery and wavering. It happens during the day time from what I've seen and only when looking from a considerable distance.

submitted by /u/krowzkore
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Can plasma electrocute you?

Posted: 28 Jul 2017 08:24 AM PDT
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Friday, July 28, 2017

Why do some people have good sense of direction while other don't? Do we know how the brain differs in such people?

Why do some people have good sense of direction while other don't? Do we know how the brain differs in such people?

Why do some people have good sense of direction while other don't? Do we know how the brain differs in such people?

Posted: 28 Jul 2017 03:54 AM PDT

Do all electrons, protons and neutrons have the exact same mass and volume or are there slight variations?

Posted: 28 Jul 2017 05:49 AM PDT

If the mass of an electron is said to be 9.10938356 × 10-31 kilograms, are there electrons that weight 9.10938356001 × 10-31 kilograms or 9.10938355999 × 10-31 kilograms?

Or are they all absolutly, 100%, without a doubt exactly the same mass and volume? Is there a way to tell them apart? can we know if the electron/proton/neutron that we are observing is the same one that we observed before?

submitted by /u/Vovabs
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Which is better for thermal protection/control, light colors or dark colors?

Posted: 28 Jul 2017 05:56 AM PDT

Videos online have said that commercial aircraft are white in order to provide thermal protection from the Sun, but the SR-71 flew much higher, thus exposed to far more radiation from the Sun than any other aircraft, and it was painted black, according to Ben Rich, for better thermal protection. So which is the true better option?

submitted by /u/ripplecutbuddha2
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Marine biologists use submarines with bright lights to film deep sea creatures, many of which have very large, sensitive eyes. Are the retinas of these animals damaged by these lights, and do they try to avoid the subs?

Posted: 27 Jul 2017 12:30 PM PDT

Why are security features in government documents and currency made to fluoresce in ultraviolet light as opposed to infrared light?

Posted: 28 Jul 2017 01:36 AM PDT

A group of my friends who were Canadian were travelling abroad and I remembered seeing an image of the national passport on the site, imgur and how the pages 'glowed' in comparison to other passports so I decided to buy an UV flashlight online and sure enough we were amazed.

But it brought me thinking about how more expensive ultraviolet lighting is and why would the government not cut costs by using features that fluoresced in infrared instead. Is it because of a practical issue involving science or a security issue?

submitted by /u/femmejean
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Why is it when people are completely paralysed, the only things they can move is their eyes? What makes the eye muscles different to any other muscles?

Posted: 27 Jul 2017 05:40 PM PDT

Why is the sky above me darker than at the horizon?

Posted: 27 Jul 2017 07:02 PM PDT

When exercising, why do they recommend to breath in through your nose, and exhale through your mouth?

Posted: 27 Jul 2017 03:04 PM PDT

Why do our breath stink when we are hungry?

Posted: 27 Jul 2017 06:31 PM PDT

How do marine invertebrates, like octopuses, show up in the fossil record if they don't have bones? Wouldn't they simply decompose and leave no evolutionary record?

Posted: 28 Jul 2017 02:04 AM PDT

What makes birds reptiles?

Posted: 28 Jul 2017 07:52 AM PDT

I am a biology major in college and it has been drilled into my brain that birds are reptiles, however many people don't agree. Surprisingly, many of these people have a scientific background. Their main argument is that birds are a completely different class from reptiles.

submitted by /u/AshleyNunez
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Does picking 4-leaf clovers have a selective breeding effect?

Posted: 27 Jul 2017 06:06 PM PDT

How do plants know when to start blooming?

Posted: 27 Jul 2017 07:32 PM PDT

Do plant hormones have something to do with it? Is it triggered by temperature?

submitted by /u/reallyageek
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How far does an average atom travel in one day?

Posted: 27 Jul 2017 11:10 PM PDT

A laser diode allows current to flow in the opposite way?

Posted: 28 Jul 2017 06:02 AM PDT

I know it works totally different from L.E.D.,but why it's called diode?

submitted by /u/Doctor-Jackall
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Can you get a sun tan/burn through glass?

Posted: 28 Jul 2017 04:30 AM PDT

For example if you sit inside and the sun shines on you through a window.

submitted by /u/pclpcl
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What happens as we approach absolute zero and how close can we get?

Posted: 27 Jul 2017 10:32 PM PDT

When you are in a dark room for some time, and get out into a bright room, your eyes/head hurts. What is the mechanism the causes this pain? Is it some muscle contracting next to your eyes? Is it some special pain sensor cell that has this only function (cause pain if too bright)? What is it?

Posted: 27 Jul 2017 06:25 PM PDT

If there is a little bit of time unaccounted for in a single day and single year on earth, why didn't we just create a unit of time that would have made everything accounted for?

Posted: 27 Jul 2017 07:15 PM PDT

For example, make the second just slightly longer to fill the gap.

submitted by /u/dw_junkie
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Are stages of past rockets (pre-Space Shuttle Columbia) still in Low Earth Orbit as flying debris?

Posted: 28 Jul 2017 12:12 AM PDT

I know that for many months, if not years, that separated rocket stages and so on will linger in LEO as flying debris, although there are exceptions to that. Is it possible that certain parts of the Saturn V that carried out the Apollo 11 mission is still in the Earth's orbit for example?

Not only that, but how dangerous will space debris be in the next 50 odd-years? I've recently been watching "Planetes", which inspired this question.

submitted by /u/SpartanOfThePast
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Why is the green background used for special effects?

Posted: 28 Jul 2017 12:06 AM PDT

And why not red, blue or any other colour?

submitted by /u/LUCASE07
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How do we get advanced notice on earth of astronomical events like solar storms or the recent gamma ray burst?

Posted: 27 Jul 2017 02:17 PM PDT

As far as I know, these two events travel at the speed of light, and we obviously don't have any way to transmit data faster than that. Are there precursors to these events that reliable tell us they are coming?

submitted by /u/elcapitanpdx
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What are those squiggly heat waves that sometimes radiate off hot stuff?

Posted: 27 Jul 2017 06:28 PM PDT

What is happening when those squiggly "waves?" appear? For example, when grilling and you shut the lid, you can see these things radiate off the top.

submitted by /u/pete_pirahna
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Thursday, July 27, 2017

Do microwaves interfere with WiFi signals? If so, how?

Do microwaves interfere with WiFi signals? If so, how?

Do microwaves interfere with WiFi signals? If so, how?

Posted: 26 Jul 2017 03:14 PM PDT

I've noticed that when I am reheating something in the microwave, I am unable to load any pages online or use the Internet (am still connected) but resumes working normally once the microwave stops. Interested to see if there is a physics related reason for this.

Edit 1: syntax.

Edit 2: Ooo first time hitting the front page! Thanks Reddit.

Edit 3: for those wondering - my microwave which I've checked is 1100W is placed on the other side of the house to my modem with a good 10 metres and two rooms between them.

Edit 4: I probably should have added that I really only notice the problem when I stand within the immediate vicinity (within approx 8 metres from my quick tests) of the microwave, which aligns with several of the answers made by many of the replies here stating a slight, albeit standard radiation 'leak'.

submitted by /u/SplimeStudios
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If a bottle is completely filled with water and I shake it. Does the water still move inside?

Posted: 27 Jul 2017 07:07 AM PDT

We seem to think of and display space as being very "horizontal." What would happen if you left Earth and flew "down"?

Posted: 26 Jul 2017 07:15 PM PDT

What process does a Quantum computer undergo, at an atomic level, to "read" Qubits, and how do the Qubits collapse into the state which solves the task?

Posted: 26 Jul 2017 09:47 AM PDT

I'm doing a project on Quantum Computing and I've hit a bit of a wall when it comes to Qubits being in the "right" state as it were.

As an example, if a Quantum computer were asked to find the two prime factors of a number (like in decryption/encryption), how would the Quantum computer read the selection of Qubits to give the correct solution?

The only way I can think of this happening is to have a selection of logic gates that somehow collapse the Qubit into the correct state when observed; however, I'm not too sure how this actually would work with Qubits.

Any overview/condensed answers would be as much appreciated as those which go into a more atomic/chemical depth about how it would all physically function.

Cheers!

submitted by /u/tooditoo
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If an infinitely powerful computer had a complete snapshot of the universe, by which I mean every possible datum about every bit of matter or energy, could a perfect simulation accurately predict the future, or is there some intrinsic randomness in the system?

Posted: 27 Jul 2017 03:32 AM PDT

[Computing] Why is Moore's Law predictably incremental?

Posted: 27 Jul 2017 05:29 AM PDT

Many people are familiar with Moore's Law, which states that the transistor count of high-end integrated circuits doubles roughly every 18 months. This, of course, is because the transistors themselves getting smaller and smaller.

Looking at the past quarter century, we've seen the process size of high-end circuits shrink from around a micron to just a few nanometers.

When you look at Intel's roadmap, they usually have a few die shrinks plotted out, years into the future.

My stupid question is: Why is this so predictably incremental? I know they sometimes run into barriers that must be overcome, but barring those, what prevents companies like Intel from releasing chips built on a 500 nm process one year to a 45 nm process the next?

If it's technological barriers, how are they so predictably overcome? Or is it just marketing, always wanting to give people a new, faster processor to buy?

submitted by /u/CardassianNeckTrick
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How can we tell which direction a sound is coming from?

Posted: 27 Jul 2017 04:59 AM PDT

what makes certain areas of the brain particularly suited to a task?

Posted: 27 Jul 2017 04:14 AM PDT

e.g. wernicke's area is associated with speech production. Why is it that this area rather than another is dedicated to this task? Is the reason structural?

submitted by /u/VeryWorriedPerson
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Does humidity effect Digital Over the Air TV reception?

Posted: 27 Jul 2017 03:47 AM PDT

I have only a roof antenna. When OTA went digital it changed for the worse. I have had 2 new antennas installed since then and it seems the best reception is on very dry days. Is this just in my head?

submitted by /u/lespaulstrat2
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Would being underwater help survive a nuclear bomb?

Posted: 26 Jul 2017 05:01 PM PDT

If I jump in my pool, on the river near my house knowing that a nuclear bomb, or atomic or H-Bomb exploded around 10 km from my house, would I survive?

The way I see it is that water will protect me from the heat, so then I will be able to surface up after the explosion and escape.

submitted by /u/pandoracube
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What is the smallest thing we can directly observe with any type of equipment?

Posted: 27 Jul 2017 01:26 AM PDT

Why is it that feces is almost always brown?

Posted: 27 Jul 2017 05:00 AM PDT

I am wondering why poop is so often brown in mammals. I know that it can be other colors, such as black or green, based off of certain factors. My question is, why is it usually brown regardless of the color of the food eaten?

submitted by /u/TimeCat27
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What effect does cannabis use during pregnancy have on the offspring? Are there any associations with development of mental illness?

Posted: 26 Jul 2017 08:30 PM PDT

It seems that the most current literature is limited, since the majority of research and studies were done back in the 1980s when the potency of cannabis was much lower than it is today. I am researching this topic for a paper and any help would be greatly appreciated!

submitted by /u/MsPoco
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Why does it take thousands of gallons of water to make a single pound of beef?

Posted: 26 Jul 2017 07:05 PM PDT

I have been looking into animal agriculture lately and I am bewildered by the amount of water it takes to produce beef. Some sources say it's around 5,000 gallons of water to produce one pound of beef. Why is that?

submitted by /u/Samwich008
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Based on the Voyager probe trajectories, is it possible to calculate where they will end up thousands or millions of years in the future?

Posted: 26 Jul 2017 05:55 PM PDT

Do more intense stimuli require more effort from our perceptual structures to observe?

Posted: 27 Jul 2017 05:10 AM PDT

What I really mean is, when a stimulus is more "intense", like when we're looking at a particularly bright scene or listening to something very loud, does the body have to expend more energy to perceive these high energy phenomena? I was thinking maybe your sensory neurons would have to go through/cycle neurotransmitters more rapidly, or that the neurons in the brain might have to fire more frequently, but I'd like to hear from someone who knows more about molecular cell biology than myself.

submitted by /u/arborescere
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How is the native origin of a plant determined?

Posted: 27 Jul 2017 04:50 AM PDT

For foods and plants that are cultivated globally, what is the methodology for determining their native origin?

submitted by /u/harlequinrose
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Why do you need uranium 235 and not uranium 238 to source weapons?

Posted: 26 Jul 2017 01:51 PM PDT

Should not be the 238 heavier, and therefor more unstable?

submitted by /u/the_HonZ
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How is the Dead Sea the lowest point on Earth ( 400m) if the Grand Canyon has a depth of 1800m?

Posted: 26 Jul 2017 10:03 PM PDT

On a chemical level, why are painkillers and other medications contraindicated with alcohol?

Posted: 26 Jul 2017 05:16 PM PDT

I understand that the effects of certain medications can be exacerbated by consuming alcohol. On a chemical and metabolic level, what exactly happens in these interactions?

submitted by /u/kazman101
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How fast is the air moving into a fan relative to the air moving out?

Posted: 26 Jul 2017 07:12 PM PDT

How can birds sit on the uninsulated cables on power lines without dying?

Posted: 26 Jul 2017 06:45 PM PDT

in our neighborhood there are two uninsulated live wires and then some other insulated cables below them on the power poles. How are birds and squirrels able to touch the uninsulated ones without being shocked?

submitted by /u/VideoGameLover
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