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Wednesday, February 3, 2016

What is the biochemical process in seeds that keeps track of cold temperature so that seeds germinate at the correct time?

What is the biochemical process in seeds that keeps track of cold temperature so that seeds germinate at the correct time?


What is the biochemical process in seeds that keeps track of cold temperature so that seeds germinate at the correct time?

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Many seeds require a period of cold (stratification) before germinating. How does the seed know that enough time below a certain temperature has passed before germinating? Obviously I realize that temperatures rise in the spring triggering germination but when people are trying to grow seeds they'll put them in the fridge for a certain period of time. The seeds will only germinate after they have spent that minimum amount of time in the cold. Removing the seeds early won't cause germination despite the fact that they went through a cold period.

submitted by /u/noodledoodle3
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Does the fetus absorb hormones such as cortisol or endorphins from the mother? Does the baby gets dependent and expects to receive it after birth?

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For example, if the mother is happy and cheerful throughout the pregnancy and releases fluxes of endorphins, does the baby absorbs it as fetus, and expects the flux of endorphins after birth?
Can lack of hormones be a reason for unrest in a baby - until they get 'rehabilitate'?

submitted by /u/am_i_here
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If you could use super slomotion camera that could see light move, what would you see, sitting in a room when you flipped the light switch off? A washing over of darkness, emanating from the light source- or just sudden darkness?

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Since E=mc^2, does a photon create a gravitational field ?

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Is a Single Measurement Precise?

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I just got back my science midterm and one of the questions I got wrong was bothering me. This was the question (not word for word of course, but same idea).

The actual mass of object A is 56.8842 grams. Which of the following is the most accurate measurement of object A __? Which is the most precise __?

A) 55.937 grams B) 57 grams C) 56.299104324 grams

I wrote in B for being the most accurate (it's the closest to 56.8842).

However for the second part I simply wrote "none" because I remember learning that precision comes from having multiple consistent measurements, and we were being asked about a single measurement. I was confident that I caught a trick question, since my teacher has done trick questions on previous tests, but they marked me wrong. They said answer C was correct because precision comes from having the most significant digits.

Am I wrong? I feel like the way this question was asked is a bit confusing, so please explain in detail whether or not I'm missing something or outright wrong.

submitted by /u/OhMyPasta
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Why does the derivative of acrtan(x) look like the normal curve?

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I looked up the equation for the normal distribution and I can't see any connections between it and 1/(x2 +1). Are they related somehow? Or are they not really that similar and just mildly resemble each other? Thanks!

submitted by /u/icebergelishious
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When did we become aware that there is no life on Mars?

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Back on a time before the space exploration, we didn't really know very much about our neighbous in the solar system. So there was a time when the scientific community didn't really know how was the conditions in Mars (and, why not, Venus).

My question is: when did we learn that these places are sterile? How did the scientific community react? Where they expecting something else?

submitted by /u/alvesjnr
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Are newborns just 'blank slates'? In other words, can you train a newborn to grow up to be anything you want (a doctor, hitman, mathematician)?

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Can Galaxies "Die" and What Might it Look Like?

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Could someone please give a scenario in which the cardinality of an infinite set becomes important?

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Could someone describe for me a case in which it would be necessary to denote the cardinality of one infinity as opposed to that of another, and what branch of mathematics this falls under? I'm having trouble thinking of a practical example other than the ring of natural numbers compared to the set of real numbers.

submitted by /u/c3n3k
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Is there evidence of a moon orbiting a moon orbiting a planet?

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Has there ever been evidence of a smaller object orbiting the moon of a planet?

submitted by /u/Retardhunter
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If the edge of the observable universe is 46.5 billion light years away, why is the most distant object ever observed (EGSY8p7) only 13.2 billion light years away and still considered to be 13.2 billion years old?

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Edit: The answer is, it isn't. The figure of 13.2 billion light years is "light travel distance" not "actual distance". "Actual distance" to EGSY8p7, being the distance as a result of universal expansion, is approximately 30 billion light years.

Thanks /u/adamsolomon

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

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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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How can a black hole emit x-rays when its gravity is so strong that even light cannot escape?

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What would happen if you frayed the ends of hundreds of small wires connected to two ends of a battery, and brushed them together?

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Would it be possible to use GFP to create glow in the dark tattoo ink?

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Why is it that some craters, notably on the moon, have a small elevation in the centre/point of impact?

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i've read that the central uplifts are due to gravity but I don't understand the role of gravity there.

submitted by /u/Legal_loophole
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Why is nitrogenase not used in industrial production of fertilizer?

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I was curious if there is a specific reason that we have not made a genetically modified organism that could secretes or at least produces nitrogenase. Is it more complicated, why is this not a practical why to produce fertilizer? Is this currently being researched?

submitted by /u/CausticCatalyst
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This reasoning shows that protons have no energy (or momentum). Where did I go wrong?

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Momentum is equal to the mass of an object*its velocity. A photon is massless, therefore it has no momentum. When you plug this into E2 = (pc)2 + (mc2)2, it would mean that photons contain 0+0=0 Joules of energy. Now, we all know that is far from the truth and that photons have both energy and momentum. So, where did my reasoning go wrong?

submitted by /u/MVP_Redditor
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Can the collision between two photons create two electrons?

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I have read that it can create an electron as long as the energy in the photons is bigger than the rest mass of an electron. Can we have photons whose energy is greater than the rest mass of two electrons?

submitted by /u/oTomas
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Is it possible to diffract bacterium?

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In a similar fashion to electron diffraction, is it possible to diffract bacterium?

submitted by /u/Branwolf
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Tuesday, February 2, 2016

What is the highest resolution image of a star that is not the sun?

What is the highest resolution image of a star that is not the sun?


What is the highest resolution image of a star that is not the sun?

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Why do enzymes have such a higher affinity for transition state analogues compared to the substrate or product?

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I've read the wiki page on it and other sources. I guess I understand the how, but I'm having a hard time with the why.

submitted by /u/WaterChemistry
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Why does pressure decrease as velocity decreases?

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Using the equation A1v1 = A2v2, we know that velocity and Area are inversely related. Using the pressure equation, we can say A = F/P. We can then say (F1/P1)v1 = (F2/P2)v2. Shouldn't velocity and pressure be directly related?

submitted by /u/firewall245
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How are satellite's able to broadcast hundreds of HD channels, given limited bandwidth, spectrum, and power?

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How is it that DirecTV and Dish network are able to broadcast so many channels? I am guessing since satellite's are primarily a one way connection, they are concurrently broadcasting all channels and streams down to earth at any given time. How is this done with limited bandwidth and spectrum? Also, how much power do these consume? It seems like these satellite's would require tons of power for receiving, processing and sending the signals.

submitted by /u/hoti0101
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¿What are your thoughts about the flat earthers?

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I've seen a lot of comments in videos arguing that the Earth is in fact flat, things like the government trying to make us think that the Earth is round, even saying that gravity isn't like what we are told. I don't follow that 'belief' (because as I saw it started mostly as a cult or a sect), because well, there are many proofs that the Earth is actually round, people have seen it from space, not CGI, nor false images or edited. And it really butthurts me when I see one of these guys out there making up data, facts, or having so called "valid arguments". You could put some facts on the comments...

submitted by /u/QueWeaHermano
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How do we mathematically describe the motion of ocean waves, or waves at a fluid-fluid interface?

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Do magnetic fields affects our brains connections?

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I learned that the Faraday-Lenz law tells that a conductor in a magnetic field will react in different ways (don't know how actually). So this question came out in my head, are our neuronal connections affected by a large magnetic field, despite if it is a variable one or a static one?

submitted by /u/hyperm36
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How much does the sun's gravity influence our pull towards the earth?

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I've included a picture to help my question.

Person B is pointing exactly at the sun. Person A is on the exact opposite side of the earth. Assuming person A and person B are exactly the same in mass, let's say 100 kilograms, does the sun's pull make person A weigh more than B?

If so, how big is this difference between them?

submitted by /u/Mc_Smack
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Instantaneous communication via quantum entanglement?

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I've done some reading about the nature of quantum physics, and have heard it explained how despite the ability for quantum particles to effect each other at great distance, there is no transfer of "information." Where the arbitrary states of "up" and "down" are concerned there is no way to control these states as the receiver sees them. They are in fact random.

But I got to thinking about how we could change what event constitutes a "bit" of information. What if instead of trying to communicate with arbitrary and random spin states, we took the change in a state to be a "1" and the lack of change to be a "0."

Obviously the biggest argument against this system is that sometimes a quantum state will not change when measured. Therefore, if the ones and zeros being transmitted only have a 50% chance of being the bit that was intended.

What if then, to solve this problem, we created an array of 10 quantum particles which we choose to measure, or leave alone in exact 1 second intervals. If we want to send a "1" to the reciever we first measure all 10 particles simultaneously. If any of the receiver's 10 particles change state, then that indicates that a "1" was sent. If we want to send a zero, we "keep" the current measurement. Using this method there could only be a false zero 1 out of 210 times. Even more particles in the array would ensure greater signal accuracy.

Also, we could increase the amount of information being sent by increasing the frequency of measuremt. Is there something wrong with my thinking?

submitted by /u/labowley
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Why is Seattle so much warmer than New England, both equally north?

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To change from D to L-Glucose, I've been told we switch the orientation of the last chiral carbon. However, D and L glucose are enantiomers, but switching the final carbon as instructed makes it not an enantiomer. How is this the case?

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My head hurts thinking about it for too long.

Thanks for your input!

submitted by /u/Neechevo
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Why are there different types of antennas?

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I mean, you could just use differently sized dipole antennas for everything, or could you? I am trying to get a hand on SDR but I can't find an overview what antenna would be good for what application

submitted by /u/D4nte188
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What animals, besides humans, have been observed teaching behavior rather than merely learning it, and to what extent?

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I can teach my dog a trick, but clearly he can't teach another dog tricks. Gorillas have been taught sign language, but can they in turn teach it to other gorillas or humans? Crows learn creative ways to crack open nuts, but do they deliberately teach their methods to other crows?

submitted by /u/WildBilll33t
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What temperature does water change from cold to hot to touch, on average?

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Why does water "feel" hot or cold at a specific temperature? Doesn't seem to have to do with body temperature as 98.6 degree Fahrenheit doesn't seem to be warmer than "neutral" temperature, can someone please explain?

submitted by /u/RandyScavenge1
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Are there any attempts to explain the cause/source of the existence of newton's laws, if so then how successful are they?

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Why aren't the Nitrogens on Methyl Azide bonded into a triangle?

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Methyl Azide (CH3N3) as far as I know the bonds between the nitrogens of methyl azide are a resonating triple bond with alternating negative formal charges on N(1) and N(3). Why wouldn't the nitrogens form a triangle shape with the two nitrogens not attached to the carbon forming a double bond two themselves and single bonds to the N that is attached to the carbon? Also wouldn't this theoretical molecule be more stable because no atom on it has a formal charge?

submitted by /u/Quinn94
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How effective are dialysis machines, and whats keeping them at that current effectiveness?

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Monday, February 1, 2016

Do bacteria change the nutritional content of milk when they turn it into yogurt?

Do bacteria change the nutritional content of milk when they turn it into yogurt?


Do bacteria change the nutritional content of milk when they turn it into yogurt?

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We make our own homemade yogurt, by heating milk in a slow cooker, then cooling it and adding a starter culture to sit overnight. This has led me to wonder whether the nutritional content of the resulting yogurt actually differs from the milk we put in.

Could the yogurt have more or fewer calories than the original milk? If so, where did the extra calories come from, or where did they go?

Is it possible that the yogurt has more protein, or different vitamins? What would be used up from the milk in order to produce these?

submitted by /u/Scrumpy7
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Assume I could travel 1000 years back in time...what foods/fruits I could ask for and not be surprised by it's appearance or taste?

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I know that the definition of a strawberry has changed a lot over the past 100 years so, what can I expect of fruit and food if I were to go back earlier?

submitted by /u/phrresehelp
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By the 3rd lifetime episode of major depression, there's a 99% chance of an episode happening again. Are there any scientific publications on the optimal way for someone to recover from a depressive episode and prevent another? Or the mechanisms behind recovery?

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Please link to publications. Thank you in advance.

submitted by /u/Grace-Tech
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Is it possible to start a fire with superheated steam?

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When scientists say "The fundamental forces were decided in a fraction of a second after the big bang", what does that mean?

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I apologize beforehand if this question is confusing, I'm having difficulty figuring our how to word this exactly.

I've heard this phrase said a number of times before, but I'm not entirely sure what exactly this implies. For instance, the ratio between strong and weak nuclear forces is included in this statement. Are there some conditions in which the ratio would have changed?

Essentially, I'm curious about the mechanics of "determining the fundamental forces". Can anyone give a better explanation for this?

submitted by /u/Raknarg
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If the universe is essentially a non-uniform vacuum, could the differences between these areas exert a force between them?

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Sorry if this is a dumb or basic question. I'm not very smart so I just want to be able to wrap my head around this. Blame Mythbusters for lifting a car with a household vacuum if you must. It all made me think of dark energy and how the vacuum of space actually works.

Would a complete vacuum in one region of space exert any influence over a non-complete vacuum right next to it? Would there be pressure differences that would equal out over time as one pulled matter towards it from the other? Do the variable parts of the vacuum of space have any interrelationship at all or is it all just passive without an energy source powering one part or another as there would be with a home vacuum cleaner creating the vacuum?

submitted by /u/Furry_Prick
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Electron Configurations & the Pauli Exclusion Principle - How can an atomic orbital (p,f,d etc) hold more than two electrons if the electron has only two spin modes?

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Do the other quantum numbers come into play to allow non-S orbitals to hold three or more? I'm definitely missing something here, it seems like what I've read about the PEP doesn't line up with, well, the entire periodic table.

submitted by /u/Aplabos
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Can the hardness of rubber change after being under cyclic loading (compression and tension)?

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I know that hardness is typically considered a material property but I also know enough stress will create changes in the molecular properties of rubber.

In the long run I'm trying to relate an easily measurable property of rubber to its lifespan under cyclic loading. Any fingers to point me in the right direction would be great however a simple answer to the titled question would be greatly appreciated.

submitted by /u/ColonelCo
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What's happening inside a propane cylinder when it's being filled?

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I understand that propane in a cylinder is kept in a liquid state at ambient temperature when the pressure in the vapor space reaches a certain level.

I'm just curious what's happening to the gas and liquid inside a tank that is being filled with liquid propane.

Are the pumps typically used strong enough to force liquid into the vessel and cause the vapor being compressed to condense, or is some other physical process happening?

Thank you.

submitted by /u/ShellAnswerMan
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Recently I read that recombination (the coupling of electrons and protons to form atoms) happened 378,000 years after the Big Bang. How can this estimate be so precise?

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Why do flashing lights cause seizures?

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I've never understood how epileptic seizures work. When I watch things that have a lot of brightly-colored flashing lights my eyes hurt at most, but my brain seems okay and everything else seems fine. I don't understand how exactly this can induce a seizure in people and would like to know more.

submitted by /u/Lqnc
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(Physics) why do space agencies not build a plane that can exit the atmosphere instead of shooting a rocket into space?

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My thought process is it is easier to walk up a hill then climb straight up.

submitted by /u/nomansnomad
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Why is easier for bacteria to develop in stagnant water than in running water?

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How can "It's current that kills not voltage" and V=IR both be true?

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What I mean is that if voltage is proportional to current (given constant resistance across the person) then it seems meaningless to say that it's current and not voltage that kills. Unless maybe what they mean is that in these high voltage/low current circuits as soon as the circuit across the person is made the effective voltage across the person drops dramatically. Like for instance if the circuit has a lot of resistance in it then it can nominally have a high voltage drop across an open switch but as soon as it's closed the voltage drop falls to nothing. Or maybe this has something to do with quirks of AC?

submitted by /u/nitram9
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Is it possible to create a solution with a net charge?

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Is there any way to isolate either an anionic or a cationic species in solution and then remove it? The only way I can think of removing a charged particle is by adding an equal amount of oppositely charged particles and reacting them out or by using a magnetic field and removing samples from one part of the solution.

submitted by /u/MIKE6792
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If I shone a very bright infrared or UV (non-visible EM waves) flashlight into my eyes, would I notice it? And could my eyes be damaged by it?

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Since staring at the sun or a bright flashlight can damage your eyes, I'm wondering if non-visible light will do the same, and if I would notice any immediate effects if it happened.

submitted by /u/Frederix_
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So its been over a year since Philae landed, have we learnt anything new?

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Was reading old archives and stumbled on this;

https://www.reddit.com/r/askscience/comments/2moow4/has_rosetta_significantly_changed_our/?

The top response was that we hadnt had enough time to analyze the data. Have we now?

 http://m.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions 

Just finished reading this FAQ which outlined some of Rosettas goals and objectives, keen for the results!

submitted by /u/jeffrey2ks
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How do we know what the milky way galaxy looks like?

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As in shape, size, density, etc. I know that we haven't sent any satellites or probes outside of our home galaxy, and seeing as how we cant look at our galaxy from the "outside" like we can do to other ones, how is it that we can tell what it looks like?

submitted by /u/craftycommando
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How does nutrition effect the cognitive functioning of the brain when blood is seperated from the brain?

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As far a I'm concerned the blood circulation transports the nutrients all over the body. But since the brain doesn't let any blood in I was wondering how food can effect the cognitive functioning. I've read stuff about omega fatty acids having positive effects, but don't really understand why.

submitted by /u/sii_rida
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If a molecule absorbs sufficient energy to be elevated to a vibrational level that is higher in energy than the first excited singlet state, is it possible for the molecule to remain in the ground singlet state? Or is it by default then in the first excited state?

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