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

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

submitted by /u/grategatsby
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How much energy does it take to make an average LED indicator blink?

Posted: 28 Jul 2017 03:25 PM PDT

submitted by /u/blit
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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

submitted by /u/WHdrazzineddi
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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

submitted by /u/IonutRO
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