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Friday, August 19, 2016

Why do Cockroaches die on their backs so frequently?

Why do Cockroaches die on their backs so frequently?

Why do Cockroaches die on their backs so frequently?

Posted: 18 Aug 2016 09:14 AM PDT

Around my school I often avoid stepping on a dead roach, but for some reason these dead roaches are always on their backs. What would compel an insect with a microscopic brain to flip over before they die of natural or possibly otherwise causes? It seems a pointless habit and yet Every dead cockroach I have ever seen does that. Is there an evolutionary advantage to such a strange occurrence?

submitted by /u/arthursbeardbone
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Can a laser beam occur naturally?

Posted: 18 Aug 2016 07:55 PM PDT

Without human intervention, anywhere in the universe?

submitted by /u/canbeanyone
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In the average human lifespan, how many viruses do we contract, and overcome?

Posted: 19 Aug 2016 04:56 AM PDT

Are flies dirty?

Posted: 18 Aug 2016 01:52 PM PDT

Do flies actually carry disease/germs/etc in and on themselves? Does a fly landing on food contaminate it?

submitted by /u/quatch
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How many dimensions are there and can they be described or what do they look like and how do they work?

Posted: 19 Aug 2016 04:15 AM PDT

I know what the 1st, 2nd and 3rd dimension looks like but are there more?

I've seen some things talking about dimensions up till the 9th but i can't make my mind up on how what they look like or can they simply not be described?

submitted by /u/Supaaa_
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What is the probability of a star not having planets?

Posted: 18 Aug 2016 01:04 PM PDT

Can it be that all stars have/had planets at some point in their life-cycle? Or having planets is as unique as planets having satellites(moons)?

submitted by /u/Unstoppable_ego
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How long is the process of a supernova?

Posted: 18 Aug 2016 08:12 PM PDT

How long does the initial explosion take? One second? One minute? One hour? Several years? Also, how long does it take for a supernova to become a neutron star/black hole.

submitted by /u/HeilHitler_
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If you could actually hold liquid magma and it not burn you, what would it feel like in your hands?

Posted: 18 Aug 2016 08:21 PM PDT

How much does a virus have to change for our immune system not to recognize it?

Posted: 18 Aug 2016 01:19 PM PDT

I've always heard that old saying 'you never get the same cold twice.' And the flu needs new vaccines every single year. It makes me wonder, how different can the cold be? It's still a cold, but somehow different enough to bypass what my immune system 'learned' about all those previous colds.

submitted by /u/Cooleosis
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What was the Huygens camera made of?

Posted: 18 Aug 2016 03:48 PM PDT

The atmosphere and conditions of Titan don't seem like they'd be conducive to photography. Light amplification and such aside, it's bleeping cold there. What was the Huygens camera made of? Was it relatively ordinary and just well-insulated, or was it a bit special compared to the kind of camera I'm used to?

submitted by /u/macksting
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After the first initial moments after the big bang, why didn't the universe collapse in on itself and form a black hole?

Posted: 18 Aug 2016 11:23 AM PDT

If faecal transplants from obese donors can induce obesity in recipients, can living with an obese person increase risk of weight gain through other forms of bacterial transfer?

Posted: 18 Aug 2016 12:04 PM PDT

Is there any evidence that bacteria passed through primary and secondary contact can have the same effect as that from a faecal transplant?

submitted by /u/happy-little-atheist
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Is there a field associated with fermions?

Posted: 18 Aug 2016 02:26 PM PDT

This is my first question here, so let me know if it should be relegated to a different subreddit instead...

Struggling with understanding the foundation of the quantum nature of particles. After going through QED and The Quantum Universe, I gathered some random facts, but something is todavía missing. Please help me feel up this elephant from the different angles...

  • Is there a relationship between a photon's wavelength and the speed of change in its probability amplitude?
  • Is there a relationship between an electron's energy and the speed of change in its probability amplitude?
  • Photons and other bosons are required to have an associated field (right?...). Can it be thought of as a propagation medium of the probability amplitude, or the two are distinct?
  • If so, is there a relationship between electromagnetic properties of the photon (polarization?) and the quantum probability amplitudes?
  • If electrons (and other fermions) behave according to the same quantum rules as photons, is there a field associated with them? E.g. when we are talking about the wave equation for a fermion, what's the carrier of that wave?
  • If there is a field, is this field the same for all fermions or each of them would have its own?

Thank you!

submitted by /u/doloresclaiborne
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Why do the Heat and Wave Equations look so similar?

Posted: 18 Aug 2016 12:04 PM PDT

LaTeX: \alpha^ 2 u_ {xx} = u_ t Versus \alpha^ 2 u_ {xx} = u_ {tt}

The only apparent difference is that the Wave Equation has another derivative with respect to time on the right hand side.

submitted by /u/pipinpadlopsicopolis
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How did the separation of the American continents from Europe and Africa increase the planets oxygen levels?

Posted: 18 Aug 2016 04:02 PM PDT

Currently reading "The Universe Within" by Neil Schubin.

It states the separation of the continents and the opening up of the Atlantic Ocean led to a lot more new coastline that could erode, dumping sediment into the water covering up mud on the oceans floor that was filled with single celled creatures consuming oxygen as they decay. Because they were covered up, that oxygen became free for other uses on the planet. The book states that in the world before the continents separated we would struggle to breath sitting down vs afterwards a world existed where mammals could run around.

But I feel like I'm missing something. If the continents were connected, then there would be no ocean between them to even have an oxygen consuming mud floor. How does the creation of the Atlantic Ocean solve a problem that doesn't exist before there is an Atlantic Ocean?

submitted by /u/Bernwarning
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How does a ground/earth pin work on a plane?

Posted: 18 Aug 2016 12:13 PM PDT

I was on an American Airlines flight and noticed that there were power plug holes on the backs of the seats, 110v 60hz, they had earthing ports, how did they work?

submitted by /u/One_Nine_Three_Eight
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Why are there accretion 'disks', shouldn't they be accretion 'spheres' or 'oblates'?

Posted: 18 Aug 2016 11:58 AM PDT

I have always been quite confused by how black holes are represented to the layman. It seems the most common representation of black holes/gravity in general is to use a rubber sheet and drop a mass in it.

Using this model, it makes sense to have a 'disk' of materials. i.e. (forgive the oversimplification) if we just scatter some particles on top of the rubber sheet, then they would form a disk around the mass.

Naturally, the universe isn't a 2D rubber sheet, a black hole exists in many more dimensions. Since this is the case, wouldn't materials that that get drawn towards a black hole come from all directions? Thereby creating a sphere of materials rather than a disk?

To maybe be a little clearer, please see this image on wikipedia. The blue area is the accretion disk, but sure the black hole should be drawing the matter from the star from 'all directions' rather than on a seemingly flat plane?

Hope I made sense!

submitted by /u/SweetLordKrishna
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Theoretically, is it possible for an intelligent being living in the second dimension to 'discover' the third dimension?

Posted: 18 Aug 2016 08:29 AM PDT

Does encrypted communication "stack"? (HTTPS/VPN)

Posted: 18 Aug 2016 09:20 PM PDT

For instance, if I visit an https website such as my banking page while using a VPN that encrypts all communication, are there two layers of encryption?

If not, why not?

submitted by /u/UpvotesKnowledge
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Is there any interesting chemistry that happens with Lanthanides/Actinides?

Posted: 18 Aug 2016 09:04 PM PDT

I've never seemed to really talked about any chemistry that happens in this block of elements in any of my chemistry courses. What sort of chemistry goes on with this block?

submitted by /u/rando-m-crits
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Why are proteins often described as behaving like anions in cell membrane physiology?

Posted: 18 Aug 2016 08:30 PM PDT

I know there is a question of the permeability of the membrane (e.g. proteins not passing through membranes), but why are proteins often described as Anions in physiology textbooks.

submitted by /u/metropolispart2
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vào lúc No comments:

Thursday, August 18, 2016

How Is Digital Information Stored Without Electricity? And If Electricity Isn't Required, Why Do GameBoy Cartridges Have Batteries?

How Is Digital Information Stored Without Electricity? And If Electricity Isn't Required, Why Do GameBoy Cartridges Have Batteries?

How Is Digital Information Stored Without Electricity? And If Electricity Isn't Required, Why Do GameBoy Cartridges Have Batteries?

Posted: 17 Aug 2016 10:11 PM PDT

A friend of mine recently learned his Pokemon Crystal cartridge had run out of battery, which prompted a discussion on data storage with and without electricity. Can anyone shed some light on this topic? Thank you in advance!

submitted by /u/Rathayibacter
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Could you tell that camels have humps just by looking at their skeletons?

Posted: 17 Aug 2016 08:03 PM PDT

Like, say you had some archaeology students who were raised in a bunker and were taught everything about how to discern external anatomy from skeletal structure, but never taught that camels existed.

If they were given a camel skeleton, could they geuss that it had a hump?

submitted by /u/Bteatesthighlander1
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Is there a minimum mass to remain a black hole after it has already formed, or is this simply unknown?

Posted: 18 Aug 2016 06:28 AM PDT

If we know black holes emit radiation and would eventually evaporate given an absurdly long period of time, is there a point at which enough mass has left and it's no longer a black hole but just another very dense and potentially visible body of matter?

Say for example a star, with what we think of as the minimum mass capable of forming a black hole, is literally in the middle of nowhere and it collapses into a black hole. It would have no matter to feed on and would therefor be decreasing in mass immediately due to radiation.

It's my understanding that a black hole is finite mass in a volume approaching 0. Does this mean that once it collapses to that near infinite density, it will never cease being a black hole with an event horizon until the very last particle has evaporated due to it's near infinite density?

If this is the case, will we just end up with a black hole whose event horizon also gets incredible small? Would this mean there might be black holes out there that have event horizons a few feet in diameter or something crazy small like that?

submitted by /u/noone111111
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Does state of matter have an effect on the absorbtion spectrum of a material?

Posted: 17 Aug 2016 09:40 PM PDT

How do we know what color dinosaurs were when all we have to examine are their bones?

Posted: 17 Aug 2016 11:17 PM PDT

Why does ice have a lower resonance frequency than rocks?

Posted: 17 Aug 2016 06:46 PM PDT

Is it just because it's solid H20 or do other frozen substances have low resonance frequency as well?

submitted by /u/Psykofreac
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At what altitude above Earth do the effects of Special and General relativity cancel each other out?

Posted: 17 Aug 2016 07:43 AM PDT

First, if this question doesn't make sense, please tell me, because I am going under some very rocky understandings of special and general relativity.

So as I understand it, in special relativity, the faster someone moves, the slower time is for them, relative to someone who is stationary. In general relativity, the further away you are from a massive object, let's use the Earth, the faster time will move for you, relative to someone on Earth.

So astronauts on the ISS age slower relative to us because they are moving extremely fast, but aren't at a high enough altitude for the effects of general relativity to overcome the effects of special relativity. However, for GPS satellites which are in a higher orbit, the opposite is true.

THE QUESTION So at what orbital altitude do the effects of special relativity and general relativity cancel each other out so that no time dilation occurs relative to a man on Earth, assuming that the orbit is perfect, with the apogees and perigees being equal?

Or do I not understand something here?

Edit: Thanks for the gold, but I think agate deserved it more.

submitted by /u/Cheesewithmold
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Dopamine surges in the brain cause down regulation of dopamine receptors. Is this always true, regardless of what caused the surge? (Drugs vs. natural rewards like orgasm, food, ect)

Posted: 17 Aug 2016 04:43 PM PDT

Can overstimulation caused by abusing natural rewards be equally as "damaging" as the same amount of over stimulation caused a drug/drugs?

submitted by /u/ioncehadsexinapool
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Why does it cost so much to send trivial items to space?

Posted: 18 Aug 2016 04:21 AM PDT

I'm asking this because I was browsing /r/space and someone was talking about the statistics for the price of sending 1 kilo to space. They then claimed to send a pencil to space costs 550 dollars. How is this? Does this mean that if I accidentally have a pencil in my pocket when I go to space, someone will be out 550 bucks? Or will we just not make it to orbit?

submitted by /u/Wizzigle
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Cognitively speaking, why is it more difficult for adults to obtain a native accent of a foreign language?

Posted: 17 Aug 2016 04:03 PM PDT

Children, teenagers, and adults have different methods of learning that are effective for their brains, and they are all capable of becoming fluent in a foreign language. But it's often mentioned that children are able to obtain native accents whereas adults are not expected to. Ignoring things like not having as much time, is there any cognitive/psychological/neurological explanation for this supposed discrepancy?

submitted by /u/nullzor
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Does fusion ever happen in during an atomic bomb (fission) explosion?

Posted: 18 Aug 2016 02:44 AM PDT

Where do fish in high altitude/mountain streams and ponds come from?

Posted: 17 Aug 2016 07:20 AM PDT

I've been hiking in Europe and Asia and have seen fish even in tiny puddles at very high altitudes, close to the ice cap source of the river. How the hell do they get here? Surely both migration and reproduction is incredibly difficult against a current and in such isolated bodies of water

submitted by /u/islamicporkchop
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Would LIGO gravitational-wave detectors be able to more accurately detect the wave origin direction if a 3rd (vertical) dimension of measurement was added?

Posted: 17 Aug 2016 09:35 PM PDT

LIGOs such as those in Hanford, WA and Livingston, LA are currently able to detect gravitational waves by measuring the time it takes for two laser beams to travel through two 4 km perpendicular tunnels (let's call them x and y). If I understand correctly, when a gravitational wave is detected, the data from x and y can be used to narrow down the direction of the wave's origin, especially when data from both LIGO locations is considered. The current ability to calculate the direction of origin does not seem to be very accurate and has only a 90% probability according to the diagram on this page. Would adding a third laser detector in a vertical "z" dimension much improve the accuracy of their direction of origin calculations? Apologies if this is long winded, I just want to be as clear as possible. Thanks in advance!

submitted by /u/psahmn
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Why do stressed points on flexible plastics appear white?

Posted: 17 Aug 2016 02:40 PM PDT

Does the ocean have currents all the way down to its floor?

Posted: 17 Aug 2016 04:50 PM PDT

Is poor memory the result of inadequate registration of events, inadequate indexing and accessibility, or inadequate storage of them?

Posted: 17 Aug 2016 05:16 AM PDT

Inadequate registration of events example: a person who doesn't care enough about the topic that's being discussed, and just not 'absorbing' the information as memory.

Inadequate indexing: a person who does not store the memory with proper indexing or reference at the experience moment, or a person that's having problems retrieving the experience in retrospective due to poor indexing/accessibility.

Inadequate storage of memory is kind of self explanatory.

submitted by /u/am_i_here
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Why is heart cancer (primary cardiac tumor) so rare?

Posted: 17 Aug 2016 03:14 PM PDT

How does time reversal symmetry apply to quantum mechanics ?

Posted: 17 Aug 2016 07:51 AM PDT

I'm currently listening to an audiobook of Leonard Susskind's "The Black Hole War". In it, Susskind discusses the time-reversability of classical physics while introducing the idea of conservation of information.

That's all pretty straight forward, but he doesn't really get into how it applies to quantum physics, as the answer may be too math-heavy for the sort of book he intended.

If I've understood him correctly, he simply states that as long as you do not interact with a system before time-reversing it, any result that QM gives you is reversible.

I wanted to think about this in terms of the double slit experiment. If you attempt to time-reverse the experiment, your target emits a photon from some random spot, and the photon passes through the slits.

In a normal picture, the photon should interfere with itself at this point, just like the forward experiment, but in reality, it b-lines towards the emitter. Clearly not symmetric in time.

Which makes me think, collapsing the wave function at the target at the end of the experiment was the step that broke the reversibility. If you had the whole interference pattern intact, I'd bet you could reverse out the initial trajectory (slits -> emitter).

Is that right?

If it is, is wave-function collapse always non-reversible? Is there a larger context in which it is reversible? (e.g. Many-Worlds)

Also, why is it seemingly okay to pretend it doesn't happen and still claim that QM is still time reversible? Isn't wave function collapse destroying information all the time?

submitted by /u/PeterIanStaker
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Do flashlights and lasers have a recoil?

Posted: 17 Aug 2016 02:14 PM PDT

We know that light exerts physical pressure on objects in its path. But does the "launching" of light cause a recoil? If I were in a completely dark room and I turned on a flashlight or a laser pointer, would there by an (absolutely minute) amount of "backpressure" on the flashlight caused by the releasing of the photos in a single direction, in the same way that firing a bullet causes a recoil of the gun?

submitted by /u/bubonis
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Why is hydrostatic pressure only dependent on depth?

Posted: 17 Aug 2016 10:43 PM PDT

Hi AskScience,

I've proven this to myself mathematically (from P = F/A ultimately to P = pgD) but I can't fully grasp it conceptually. I've googled this question but I can't find a very eloquent answer

Conceptually, why is it that the pressure at depth D is the same in a cylindrical tube, a triangular container, and a container, for instance, like an upside-down T?

Thanks in advance

submitted by /u/AQueMola
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How does silicone stick to skin? (Like in strapless bras and medical pads)

Posted: 17 Aug 2016 05:53 PM PDT

I have a silicone pad for my foot to relieve pressure on a morton's neuroma. I'm curious how the silicone is able to stick so well and how it's able to be washed and reapplied. What is the specific mechanical action that's occurring on a microscopic level? There isn't a chemical aspect is there?

submitted by /u/Carbon234
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vào lúc No comments:

Wednesday, August 17, 2016

If I were to take a "frame by frame" video of a hydrogen atom and its electron, whould I find the electron moving along a trajectory or teleporting randomly throughout the cloud?

If I were to take a "frame by frame" video of a hydrogen atom and its electron, whould I find the electron moving along a trajectory or teleporting randomly throughout the cloud?

If I were to take a "frame by frame" video of a hydrogen atom and its electron, whould I find the electron moving along a trajectory or teleporting randomly throughout the cloud?

Posted: 17 Aug 2016 02:18 AM PDT

Are humans apes?

Posted: 16 Aug 2016 10:44 AM PDT

So humans are primates. And we evolved from apes. But are we considered apes from a taxonomy viewpoint?

submitted by /u/DarthDovahkiin5
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Is visibility much worse in Venus's atmosphere than Earth's?

Posted: 16 Aug 2016 02:52 PM PDT

I know the pressure on the surface of Venus is incredibly high, but does that pressure, gases of the Venusian atmosphere, and the cloud thickness significantly affect viability? If so, to what degree? If you were in some kind of super space suit that could withstand the hellish surface of Venus, would you even be able to see anything?

The pictures from the Soviet landers make it seem like the visibility is comparable to Earth on a cloudy day, but I have a feeling the camera and exposure settings might be compensating for Venus's atmosphere.

submitted by /u/RobertM525
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Why have we not used IVF to impregnate a elephant with a wooly mammoth yet?

Posted: 16 Aug 2016 07:54 AM PDT

What barriers are stopping us? Is it the science or the ethics of bringing back such an old animal?

submitted by /u/commi_furious
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Why has the "Great Red Spot" storm on Jupiter, unlike storms on Earth, lasted for so long?

Posted: 16 Aug 2016 08:54 PM PDT

[physics] Why do people say that laws of physics are time-simmetric when nothing can leave a black hole?

Posted: 17 Aug 2016 04:41 AM PDT

And what about the second rule of thermodynamics

submitted by /u/Hiephoohallo
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What does the electric field look like in a basic circuit?

Posted: 16 Aug 2016 07:33 PM PDT

Imagine a very basic circuit: a battery hooked up to a light bulb. From what I know, the battery, through its chemical constituents, creates a potential difference across its terminals, thereby generating an electric field. My question is, what does this field look like? If you were to sketch the field lines in the picture described above where would they lie? Would it only exist within the battery? and if so what keeps the electrons moving through the wire?

submitted by /u/FiresJ
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With CRISPR, is the solution to many diseases just a matter of more computer power and more efficient delivery of CRISPR?

Posted: 16 Aug 2016 03:44 AM PDT

With CRISPR, genetic material may be (somewhat) simply removed and replaced by other material. Some issues remains, such as how to get a uniform delivery throughout the organism, but that is being worked on by many teams at the moment, and will likely happen fairly soon.

So, my question is: Given enough computer power, wouldn't it be possible to analyze the DNA sequence of, say, a healthy cell's DNA and the DNA of a cancer cell, find the difference, and then use CRISPR to simply write trash DNA instead in the cancer cells, which will kill any "descendants" of the cell. I could see more or less the same method being used to kill off bacteria, simply find an unique "target" in the DNA, then thrash it with garbage DNA.

Now, I'm not a medical expert of any kind, I'm a programmer, but this is a solution which makes sense to my programmer mind. Conceptually, it's very straightforward, and mostly a matter of faster computers (which, in turn, is just a matter of time).

Am I making sense, or am I just finding a neat, but wrong, solution to a problem I don't understand? Could this be the silver bullet?

submitted by /u/ElMachoGrande
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Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology

Posted: 17 Aug 2016 08:05 AM PDT

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Economics, Political Science, Linguistics, Anthropology

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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What initiates meandering of a river channel?

Posted: 16 Aug 2016 03:54 PM PDT

Been doing some research, and the initiation on meandering seems extremely complicated and hard understand, and I was hoping someone with an advanced knowledge could help. So far 2 theories:

1) Alternation of convergent and divergent flow along the channel, combined with 2nd circulatory currents. Surface convergence at the pool induces a descending secondary current which increases the bed shear stress and encourages scouring, while surface flow diverges at the riffle producing convergence at the bed and thereby deposition - Keller and Melhorn

2) Macroturbulant flow and the bursting process envisages alternating regions of high-speed and low speed flow. Such stream-wise fluctuations in the velocity field could give rise to the necessary alternation of scour and deposition, the region of high-speed flow being associated with pools - Yalin/cliddord.

So is it a combination of turbulent flow from irregularities in either bank, resulting in a pair of surface-convergent helical cells becoming unbalanced and the forcing of the dominate cell to become reversed, resulting in the formation of a meander thalweg(erosion on one bend etc.), which ultimately has a negative feedback, inducing further meandering.

and

Macroturbulant flow and burst process, which cause differences in flow strength, thus erosion and deposition, causing the formation of pools and riffles, which in turn creates roller eddies and a thalweg.

EDIT 2: What I have on paper at the moment, but pretty sure its a mess!

Currently the initiation for meander is widely disputed, with no distinct explanation known and the idea remains speculative. Meandering is thought to occur, through the inherent properties of macrotubulent flow and burst processes (Yalin, 1992), where rivers are not perfectly uniform structures; due to localised differences in channel bank characteristics. As a result, flow will become spontaneous and turbulent, causing large scale roller eddies (Vortexis), which interact with the boundary walls. Large scale roller eddies (Vortexis) develop at both banks at an average spacing 2 π width forming pairs of surface-convergent helical cells (Figure ….). However, with the banks not having uniform boundary conditions and the flow being sporadic and turbulent, the surface-convergent helical cells will likely become unbalanced, causing a period reversal in the dominant cell, resulting in the formation of a meander thalweg and asymmetry in the channel cross-section (Thompson 1986; Knighton). Additionally the interaction between the flow and mobile channel bed, in which sediment transport is an essential element (Keller, 1973). A slight local irregularity on the bed surface causes flow deceleration and local curvature, which then leads to a relatively large local gradient in sediment transport that may grow into bed forms, bars, channels, sand waves and so on. This tendency is predicted even when flow and sediment transport equations are dramatically simplified and linearized. Linear stability analysis explores how this fundamental instability mechanism causes infinitesimal perturbations to grow to regular patterns (eg, Federici and Seminara, 2003). BAR/BEND THEORY - DISMISSED BECAUSE SUPRAGLACIAL MELT CHANNELS MEANDER WITH OUT SEDIMENT

Once meandering is initiated, positive feedback mechanisms is initiated. Water is super elevated against the outer apex, and lower water towards the inner bend, due to centrifugal forces and an in-ward acting pressure gradient. A transverse current directed towards the apex at the surface and towards the inner bar at the bed to give a secondary circulation additional to the main downstream flow, giving rise to helicoidal gradient forces which driven by the cross stream tilting of the water surface. Curvature induced not only secondary circulation but also large cross –sectional variables in the boundary shear stress velocity field. Means that a maximum boundary shear stress velocity, enters the meander at the bar head, cross the channel through the zone of greatest curvature, and intercepts the apex of the meander bend, causing an area of maximum erosion, and bank retreat (lateral migration) and pool development, whist the bar and riffle at inflection point experiences the lowest boundary shear stress velocity, where accretion of sediment occurs, causing a build-up on the point bar and riffle.

DON'T EVEN GET ME STARTED ON POOL-RIFFLE MAINTENANCE

I've been doing this s**t to long....and just need some clarification

submitted by /u/RowanHawker
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Why doesn't the neutering of animals affect their growth and development like being a eunuch does for humans?

Posted: 16 Aug 2016 03:44 PM PDT

According to Wikipedia regarding humans, "Males with testicular agenesis tend not to produce the reproductive hormone 5aDHT at any stage of their lives. As a result, they tend toward prepubescent appearance, with infantile skin texture, developing little body hair particularly in the crotch area, even vellus hair. ... Also muscular development is retarded and testicular agenetics are of rather frail build with short limbs and small hands and feet." Source: https://en.wikipedia.org/wiki/Penile_agenesis_and_testicular_agenesis

Why doesn't this happen to animals in their own way? How can male animals get neutered, and yet not suffer stunted development?

submitted by /u/gardener_in_a_war
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How do aquatic plants propagate?

Posted: 16 Aug 2016 04:02 PM PDT

To my knowledge aquatic plants don't "flower", like terrestrial plants do. Are underwater plants clones of one another, or huge colonies?

submitted by /u/s3gfau1t
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What do these parentheses mean in scientific notation? Ex: 1.616199(97)×10^−35

Posted: 16 Aug 2016 06:50 PM PDT

Follow up: Is this the most exact measurement/approximation of the Planck length?

submitted by /u/Vandechoz
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How much do we know about the sleep cycles of animals living without sunlight?

Posted: 16 Aug 2016 08:20 PM PDT

Either underground or underwater, for example bats or angler fish. They don't see the sun rise or set, so there's no reason to think they sleep and wake up every day.

Are there any animals that live exclusively away from the sun that sleep? What are those cycles based on, if not the sun?

submitted by /u/TurboChewy
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Do animals that naturally spend a lot of time high up, like birds or monkeys, ever exhibit a fear of heights?

Posted: 16 Aug 2016 12:21 PM PDT

How long did the epoch of recombination last?

Posted: 16 Aug 2016 09:56 PM PDT

I get that prior to recombination, the fully ionized plasma made it impossible for photons to travel far without scattering, meaning it was effectively opaque. But as the universe cooled, it allowed atoms to form, and opened the mean free photon path up. But how long did this process take? Everything I've seen makes it seem "sudden" but that is a very relative term when talking about universal time scales. Are we talking seconds? Years? Millennia?

submitted by /u/IGotsDasPilez
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If absolute zero is when it's completely stop moving, what about movement though space?

Posted: 16 Aug 2016 11:43 PM PDT

If something is moving through space, it can't stop moving, making it absolute zero. Are there different types of movement being described? If not, temperature must be relative right?

submitted by /u/FatGecko5
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Is there any species of mammal where there are not sex differences in behavior/temperament?

Posted: 16 Aug 2016 10:42 AM PDT

It's often thought that males are dominant and aggressive among all mammal species, but this isn't true. However, is there any species of mammal where there's not sexual dimorphism in behavior?

submitted by /u/Arca587
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Why does the observation of a qubit change it's superposition to a single state?

Posted: 16 Aug 2016 11:03 PM PDT

Could someone also define the meaning of observation in this context?

submitted by /u/iiskos
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Are Gravitational and Inertial Mass Always Perfectly Proportional?

Posted: 16 Aug 2016 09:14 AM PDT

Alternate phrasing of what I'm asking about would be: Is there any known condition under which the mass of an object with relation to accelleration is not identical to its mass in relationship to the gravitational force applied?

I know Newtonian gravity isn't quite accurate, but I never got far enough along in physics to learn the formulas for Relativistic gravity.

I guess the real question I'm asking is if there is any evidence that Gravity can be generated without classically understood mass.

Please let me know if the question I'm asking doesn't quite make sense or is being asked wrongly.

submitted by /u/Sand_Trout
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Why can't the Delayed-Choice Quantum Eraser be used for FTL communication?

Posted: 16 Aug 2016 10:00 AM PDT

The following is Kim et al. 's Delayed-Choice Quantum Eraser experiment:

A photon goes through one(or both) of two slits(A and B). Behind each slit there's a Glan-Thompson Prism that generates two identical entangled photons from one photon. One of them passes through a lens and is detected by Detector D0. The other one, depending on whether it passed through slit A or slit B, is sent to Beam Splitter 1 or 2. Each beam splitter has a 50% chance of ending up in a detector(D1 and D2) or a quantum eraser. The quantum eraser collects photons from both Beam Splitter 1 and 2, preventing anyone from knowing from which detector(and so which slit) the photon came from. The quantum eraser then sends the photon to Detector D3.

Kim et al. proved that detectors D0 and D3 don't collapse the wave function of the superposition (|slit A> + |slit B), so after sending a sufficient amount of time interference patterns can be osserved on detector D0). D1 and D2, however, collapse the wave function, so D0 doesn't detect any interference pattern. This is true even if D1, D2 and D3 are light years away from D0.

Let's say instead that I built a particular device containing D1, D2, D3 and the Beam Splitters and sent it to Proxima Centauri(distance from the Sun = 4.24 light years), where my friend John is currently living.

A certain amount of photons go through A or B(or both) and then are duplicated: one goes to D0 in my backyard, one to Proxima Centauri.

Meanwhile my friend John flips a coin and if it is head, he replaces the beam splitters with two mirrors pointed towards their corresponding detectors, if it is tail, he replaces them with two mirrors pointed towards the quantum eraser.

If John flipped tail, after a few seconds D0 will detect interference patterns. If John flipped head, it won't.

Didn't I just receive information 4.24 times faster than c?

Alternative version if you don't like FTL theories: the photons enter the LHC and 4.24 years later they are directed towards the device.

Thank you for your attention and sorry for my poor grammar (I'm Italian).

submitted by /u/smarro
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