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Tuesday, May 23, 2017

How did Max Planck calculate a Planck Length?

How did Max Planck calculate a Planck Length?


How did Max Planck calculate a Planck Length?

Posted: 22 May 2017 07:08 PM PDT

Is it possible for a moon to have its own moon?

Posted: 22 May 2017 04:06 PM PDT

Why aren't multi-electron orbitals significantly dynamic or chaotic?

Posted: 22 May 2017 04:42 PM PDT

The existence and shape of orbitals in a hydrogen atom is a straightforward consequence of spherical harmonics. But when an atom contains multiple electrons, why doesn't the many-body Coulomb repulsion between the electrons lead to chaotic or dynamic behaviour? Why do simple linear approximations work so well when there are so many interactions going on? Why is the behavior of each electron described entirely by a set of quantum numbers and contained in shells that do not change over time?

I have been told that the standard description of multi-electron orbitals using a 3n + 1 dimensional wave function in phase space is an ideal, linear approximation to a non-linear phenomenon. That's perfectly acceptable - I heard the same thing many times when I was studying electronics and signals. But a classical many-body system containing more than two bodies of equal mass and charge would behave in a highly chaotic manner (even in the presence of the nucleus). Obviously an atom is not a classical system but I do not understand which property of quantum mechanics is responsible for minimizing possible chaotic behavior to the point it can be almost ignored.

Here are some possibilities that I have considered:

  1. The Coulomb interaction is mostly canceled out due to the fact that individual electrons are delocalized.

  2. The Pauli exclusion principle prevents electrons from moving to close to each other, thus keeping the Coulomb force minimal.

  3. The Pauli exclusion principle forces each electron to take on a different, "orthogonal" quantum state.

  4. The confinement of electrons to a potential well means that they can only take on discrete energy levels which correspond to particular sets of quantum numbers.

  5. The (relatively) localized charge of the nucleus overwhelms the influence of the delocalized electrons.

  6. Atoms are generally not thermally isolated so any chaotic resonances are damped and time evolution does not take place due to decoherence.

I have no doubt that quantum numbers and shells are a very good approximation, I'd just like more clarity as to why.

submitted by /u/president_alien
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Why was such a massive, fundamental particle like the Higgs Boson so hard to find?

Posted: 22 May 2017 02:02 PM PDT

I mean, it seems kind of obvious for something tiny like the neutrino to have been difficult, because it's so tiny and barely interacts with anything.

But the Higgs, as I've heard described, is both massive... Like, much heavier than a proton or neutron, and also has to interact with all matter for it to have any mass at all. What's the issue?

Also, same question for gravitons I guess.

submitted by /u/willyolio
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Why is it that brake rotors don't technically warp but cylinder heads and blocks can and do?

Posted: 22 May 2017 02:52 PM PDT

I'm a mechanic by trade and I went to school for it for many years at night while I was in the early stages of my career but I just recently found out in another sub that brake rotors don't actually warp due to heat. I did some research and it appears from the few minutes I looked into it that brake rotors develop high and low spots due to uneven brake pad wear which causes the pulsation you feel as the driver if there is a problem. According to the research I did because the brake rotors are manufactured at extremely high temperatures they are impervious to the heat generated by the act of braking meaning that if there is an issue causing a pulsation it must be due to something other than a warped rotor. I like many other mechanics have been describing this issue incorrectly for my entire career according to what I read. That aside I got to thinking, why is it that brake rotors can't warp from the act of braking but cylinder heads can warp from overheating? The typical temperature of the coolant in the engine during normal operation is about 200 to 240 degrees Fahrenheit the actual temperature of the metal in the engine I'm not sure of but I would guess it's in the 300-500 Fahrenheit range. I would also guess that during a severe overheat the temperature might double or triple but not reach the temperature of the manufacturing process. Can someone explain how a big chunk of metal can actually warp due to an overheat condition but not a small brake rotor.

submitted by /u/greasyEUtech
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Should we be worried about SF6 as green house gas as it has ~20,000 time more global warming potential than CO2?

Posted: 23 May 2017 03:23 AM PDT

Are specialized AI chips (e.g. "TPU") only beneficial for training? Or are they needed for the actual use of the AI system even once fully trained?

Posted: 22 May 2017 08:38 PM PDT

How are antidotes and vaccines made? Additionally how do they work?

Posted: 22 May 2017 12:39 PM PDT

I know that antidotes for snake bites are made with the venom, but I don't know how exactly the process is. Similarly do vaccines use the a small portion of the disease or is that exclusively Homeopathy?

submitted by /u/SnowBabyJ
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Why are elements so magically different based solely on particle counts?

Posted: 22 May 2017 11:07 AM PDT

So I have a basic understanding of chemistry and physics, and I know that the fundamental difference between elemental atoms comes down to particles like electrons and further down like quarks. I know reactivity plays a large role in how elements behave and the number of electrons is relevant to how reactive an element is in relation to others via sharing electrons.

So my questions boil down to:

How is it that with just different numbers of particles in an atom, any given element can be so radically different? Helium is "smaller" than Lead, and it is a gas and makes your voice funny and Lead is a heavy metal that makes you sick. But iron is also "smaller" but it's also a solid and is a required part of the body as a mineral?

Based on this, is it possible that a theory could be put together to predict an elements properties just via information contained in the Periodic Table?

I'm aware of the Island of Stability. If we know of helium and iron with great certainty, and we understand how different they are, how much different might exotic superheavy elements behave? Do we have a hope of predicting this? From what we know currently, are any of those exotic materials anything more than radioactive death particles?

I know that Sci Fi likes to play with ideas about a universal source code and such, but if we were to understand the base make up of all things, would there be a limit to what we could do/understand?

Basically, it's amazing to me that the universe is built of tiny bits that can do anything we observe. That at the basest levels, we are all just particles doing what particles do. I would definitely love to have my understanding deepened and maybe my mind blown a bit more.

submitted by /u/Pyrothei
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How does the process of adding neutrons to an existing element to form a new synthetic element differ from the process of forming a new isotope of the same element?

Posted: 22 May 2017 08:16 PM PDT

How do we gather Quantum data?

Posted: 22 May 2017 08:08 AM PDT

Basically how do we learn the exact state of an atom or electron, and is there a way to do this for large groups of atoms at the same time?

submitted by /u/jamezmorrell
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Carbonaceous Chondrites, why did so many of them hit earth?

Posted: 22 May 2017 03:02 PM PDT

I was teaching my class a lesson on asteroids, comets, and meteors. I have a fairly good understanding on this topic until somebody asked me what condition made it so that so many of these Asteroids hit earth. I told them that I would get back to them, so here I am!

submitted by /u/DiamondDuck101
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Won't solar panels also contribute to global warming?

Posted: 22 May 2017 04:15 PM PDT

It just came to my mind that since most solar panels are black and they're made to absorb as much sun light as possible. If an area with no solar panels decided to add panels on every roof. Won't that decrease its albedo and warm that area even more?

submitted by /u/BroSofa
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How are wave signals generated? (Wifi, Bluetooth, etc)

Posted: 22 May 2017 09:40 PM PDT

Remotes, Bluetooth headphones, wifi, and countless other devices depend on waves. What mechanism or device creates the wave out of electricity? How does this work?

submitted by /u/Crypt_nrg
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What makes a reaction suitable for chain reaction?

Posted: 22 May 2017 05:23 PM PDT

For example, if I bombard an Aluminum atom with a neutron, how would I know if it would create a chain reaction or not? Why would it not (or maybe) behave like U-235 would?

submitted by /u/PoopsEveryday
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Have We Discovered Anything From Eco-Spheres?

Posted: 22 May 2017 01:19 PM PDT

With the popularity and widespread availability of eco-spheres, and even a large one at the America Museum of Natural History, is there anything substantial that we have actually discovered, solidified to a theory or fact or learned from the use of eco-spheres, and if so, what was it?

submitted by /u/TheJamaicanGamer
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Does the load bearing capacity of a shaft collar increase when there are more of them?

Posted: 22 May 2017 08:50 PM PDT

If I had a set screw type shaft collar like this on a rod, would adding another on top of it double the amount of force the system could sustain? In this instance, the shaft collar is sitting on a surface and the rod is in tension. Would two collars, equally clamped down, double the tension force prior to collar slippage, or does the force stay the same as it would for just one collar? Given that friction is mu*Normal, I am inclined to think that the force would stay the same, but is there an n term there for multiple friction surfaces?

submitted by /u/SF2431
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How does a pacemaker work?

Posted: 22 May 2017 11:05 AM PDT

Why can't a bare LED have a wide spectrum?

Posted: 22 May 2017 08:46 PM PDT

I ask this question because I was thinking about how white LEDs are made by secondary emission from a phosphor or multiple dies, and I thought why can't I have an LED that emits a smooth spectrum of light like a halogen bulb without a phosphor?

submitted by /u/TheSingularityEngine
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If we can see a star millions of light years away at night, does that mean that the light from the star has to have a direct path to earth with nothing in its way for the light to make it to us?

Posted: 22 May 2017 08:20 AM PDT

Can light go around the objects and still make it to us, or how can we see lights from stars millions of light years away?

submitted by /u/Meat-curtain
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If in a completely dark room a flashlight is turned on for a second why dont the photons move infinitely long so there would still be light in the room after its turned off?

Posted: 22 May 2017 08:50 AM PDT

Title says it all

submitted by /u/llHakarll
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Monday, May 22, 2017

Why does my shower curtain seem to gravitate towards me when I take a shower?

Why does my shower curtain seem to gravitate towards me when I take a shower?


Why does my shower curtain seem to gravitate towards me when I take a shower?

Posted: 22 May 2017 03:53 AM PDT

I have a rather small bathroom, and an even smaller shower with a curtain in front.

When I turn on the water, and stand in the shower, the curtain comes towards me, and makes my "space" even smaller.

Why is that, and is there a way to easily prevent that?

submitted by /u/DaftDrummer
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Does the volume of my headphones effect battery life, if so, what is the optimal listening volume for energy consumption?

Posted: 22 May 2017 01:19 AM PDT

The title says it all.

submitted by /u/deisidiamonia
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ELIMathematicianNotPhysicist: Quantum Bayesianism. What is it, and how is it different from all the other ways to look at QM?

Posted: 22 May 2017 12:58 AM PDT

Is there anything in space we can see at two different times because of the bending of light on the way here? How much of a difference could be expected?

Posted: 21 May 2017 09:11 AM PDT

I read something like this ages ago and it intrigues me. Can you really see the same thing in two places in the sky?

submitted by /u/hanoian
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What would happen if you shot a nuclear bomb?

Posted: 21 May 2017 05:40 PM PDT

Any gun, let's say like the kind of bombs used on Nagasaki or Hiroshima? Are the shells designed to withstand that? Because I'd guess a big drop has a larger momentum than a gunshot

submitted by /u/CameronBerry96
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When people take videos from older phones, why is it that the video itself will warp so that straight lines become bent?

Posted: 22 May 2017 01:11 AM PDT

How does brain control heart rhythm in people that are from neck down paralyzed?

Posted: 21 May 2017 04:28 PM PDT

If a person is paralyzed due to serious injury to their spinal cord around neck, how does the brain still control the heart or even simple breathing is possible?

submitted by /u/forexross
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Could living things sink or dive into lava? Or is it simply too dense?

Posted: 21 May 2017 05:07 PM PDT

This link is near the top of r/all right now: https://gfycat.com/GranularAnnualBactrian

The comments are full of people talking about diving in.

Would a human actually sink or even be able to get below the surface? Or is molten rock too dense for that? I've wondered this since I was a kid and saw Arnold lowering himself into molten steel at the end of Terminator 2!

submitted by /u/Madmartigan1
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Can you heat something beyond the critical point?

Posted: 22 May 2017 07:26 AM PDT

Let's say that you have water vapor at critical point, can you heat it beyond that and reach 1000 degrees Fahrenheit?

submitted by /u/clarkkentmaster
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Could someone please explain to me the incompleteness theorems?

Posted: 21 May 2017 02:00 PM PDT

I have a slight problem understanding Kurt Gödel's incompleteness theorems, as I don't have any higher education in such fields. It seems to me that it tells that math, and science by extension, can never describe the whole truth. Am I completely off the chart?

submitted by /u/Inri_magine
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Why are we unable to remember our baby memories?

Posted: 21 May 2017 04:44 PM PDT

Some dogs/cats watch TV. Do they understand what they see?

Posted: 21 May 2017 03:54 PM PDT

Especially the ones who can watch a nature program without "freaking out".

submitted by /u/Nafetsg
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What recording device can record 3D surround sound that are not just two-channel stereo?

Posted: 22 May 2017 02:26 AM PDT

The 3D surround sound I mentioned is that kind of sound that can be recognized sound changes including directions, distances and movements. It felts like what recorded is same as we hear in the real world. And we could locate sound even when we close our eyes.

submitted by /u/georgewillson818
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What Technology Would be Needed to Produce Element 119?

Posted: 21 May 2017 03:37 PM PDT

By "What technology" I mean: 1. How powerful would this tech need to be to produce element 119, and 2. What, specifically, would one need to produce element 119.

submitted by /u/SlimierPete
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Why does the liver produce superoxide radicals? My professor said it helps make hydrophobic substances more soluble in water, but I don't understand why.

Posted: 21 May 2017 08:06 PM PDT

Do pheromone sprays actually work?

Posted: 22 May 2017 05:23 AM PDT

I recently came across a pheromone forum where people talk about which sprays to use for certain occasions and the type of effects that they noticed people have when around them.

I then went to the site that the forum promotes and you have sprays that help you with attraction, help people feel good around you, make people open up to you, for trust & respect, for people to be more honest and more.

The members post great results but it feels too good to be true and the paranoid part of me thinks that what is happening is that when trying one of these sprays they're either giving their surroundings more notice to see if it's working or it's some sort of placebo effect where when they spray it confidence goes up and they report it as results.

The reason that I think that there maybe something to it is that it's not a forum with a small number of users, there are a lot of posts and threads on there and it's not like all of them can be because of the above mentioned effects.

So I'm really interested in what people on here know about this subject.

submitted by /u/nachospolsion
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How did someone work out the anatomical structure of tiny animals, such as worms, spiders and ants?

Posted: 21 May 2017 03:27 PM PDT

Why does moving air feel colder on our skin? Shouldn't it feel warmer due to friction?

Posted: 21 May 2017 09:44 PM PDT

When we burn fossil fuels, aren't we just releasing carbon that was once free?

Posted: 21 May 2017 01:24 PM PDT

I don't really understand how we can have the highest levels of CO2 in the history of earth if all this organic matter must have gotten the carbon from the atmosphere to begin with.

submitted by /u/Catdog_ywu
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Will a hair follicle that sprouted a grey hair permanently grow grey hair?

Posted: 21 May 2017 08:58 AM PDT

Let's say you consistently pluck grey hairs out if you're the type to deny it rather than embrace it.

If you pluck the grey hair, will another grey hair grow from that follicle, or could it return to your original hair colour?

submitted by /u/ThePeanut_KJD
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Does the human brain have a memory cap?

Posted: 21 May 2017 03:05 PM PDT

Do we ever reach a limit of the amount of information we can store in our brain?

submitted by /u/tuninzao
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Does "rotating artificial gravity" work in the vacuum of space?

Posted: 22 May 2017 03:01 AM PDT

Let's say there was a spaceship like in one of those science fiction films, where a part of the ship rotates to create artificial gravity.

Now what if an airlock blows out or some thing else happens so that all the air gets sucked out of the rotating disc-ring-thingy. Is there still "gravity" inside? What if a person in a spacesuit somehow enters the ring after the decompression through a hole on a wall or something like that.

Or lets say the tube isn't spinning at all, the astronaut positions him-/herself in the dead center of the pipe, then someone turns the thing on. How does the astronaut gain velocity? Or does he/she?

Some clarifications:

  1. The astronaut doesn't touch anything (walls etc.) and there's no air (no chained contact through air molecules to the structure)

  2. The astronaut is inside and in the dead center of the tubular structure moving around him/her, like the astronaut was going through a tunnel.

  3. Everything has a gravitational pull. How does this force behave in this situation since the object is all around the astronaut and constantly moving?

  4. English isn't my first language, but it's still a valid question.

tl;dr: is the artificial gravity depicted in scifi movies depended on air to function?

EDIT: Everything

EDIT 2: Oh and the ring isn't compartmentalized, it's hollow all the way

submitted by /u/UtopianKing
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On a typical electrical plug, What is reason for the little holes at the end of the two prongs?

Posted: 21 May 2017 04:20 PM PDT

Why is Isotope Fractionation important in Astronomy?

Posted: 21 May 2017 03:02 PM PDT

More specifically, isotopic fractionation in protoplanetary disks? And why is mass independent fractionation important in that context?

submitted by /u/HeavyMetalAstronomer
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Sunday, May 21, 2017

What would happen if the Earth's oceans were replaced with fresh water?

What would happen if the Earth's oceans were replaced with fresh water?


What would happen if the Earth's oceans were replaced with fresh water?

Posted: 20 May 2017 06:27 PM PDT

What does it feel like walking in areas with high radiation? Does it feel hot or something? Does it smell? Harder to breathe? Or is the only way you will figure it out (w/out a Geiger meter) is when you start to get sick?

Posted: 21 May 2017 05:55 AM PDT

EDIT: Sorry for the wrong flair. Not a science guy so I just kind of associated the elements involved with chemistry

submitted by /u/FangFingersss
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What happens to the gas inside a car's tires when it starts moving, while it's going, and when it stops after already moving? Does it stay stationary, or spin with the tire?

Posted: 20 May 2017 04:04 PM PDT

Does our atmosphere always stay a constant shape around Earth?

Posted: 20 May 2017 02:57 PM PDT

Or would it act like the water around the towel in this experiment done on the ISS by Chris Hadfield

submitted by /u/tehdubbs
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[Physics] If there are no states for an electron to occupy between conduction and valence bands, then what is the Fermi Level if it lies between the conduction and valence bands ?

Posted: 21 May 2017 03:23 AM PDT

[medicine] how come you can't just cut off a wart?

Posted: 20 May 2017 04:30 PM PDT

Which would be the problem of a supercritical helium turbine?

Posted: 21 May 2017 03:18 AM PDT

I was looking about molten salt reactors, the 3 of them sodium, fluoride and chloride salt reactors and, i did seen that in many reactor designs there's the reactor liquid fuel internal circuit, and a second circuit which exchanges heat with the primary salt, and then goes to a water heat exhanger that makes the turbine spin, thinked in deleting the intermediate circuit and send water directly to the reactor vessel with a heat exchanger. But then there's the problem of the reactions the sodium and water at those temperatures can make so i thinked why not changing water to helium at very high pressure? Is an inert gas, isn't flamable, and i think it doesn't react with salts

Which would be the pressures to mantain a supercritical or ultrasupercritical helium state at 500ºC? I would get problems trying to condesing it to delviering it to the reactor again?

submitted by /u/Comunismo_videlista
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Where does the number e come from?

Posted: 20 May 2017 02:27 PM PDT

By whom, how and when was it discovered and proved?

submitted by /u/MeatyOs
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Is there a limit to the density of matter?

Posted: 20 May 2017 04:36 PM PDT

For instance in a super massive black hole the density is greater than the density of the sun.

submitted by /u/Itrusteverything
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Efimov physics: could someone explain the significance?

Posted: 20 May 2017 09:59 PM PDT

I stumble on an article about the Efimov Effect. There were only a couple of posts on reddit about it and most of the comments were deleted.

I'm a lay person (ie. don't have a degree in physics) and was hoping someone might be able to explain why pairing three bosons is such a breakthrough. I've searched everywhere for an answer, but couldn't find anything that explained the potential applicability of this or how this alters the classical view of physics.

Is it just that it suggest things work differently at the quantum level than we think?

Thanks!

submitted by /u/joekerr37
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How can you tell if a solid ball of substance is uniformly dense?

Posted: 20 May 2017 07:47 PM PDT

Supposing that any places of lesser density are exactly centered within it, like a perfectly spherical truffle with perfectly spherical chocolate filling, and assuming you don't know what material it is so you can't just try displacement.

submitted by /u/PistachiNO
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Why is Vaseline, a petroleum derived product, good for your skin? Aren't petroleum and plastics bad for your body?

Posted: 20 May 2017 05:26 PM PDT

what is the strange pendulum effect called?

Posted: 21 May 2017 02:56 AM PDT

https://www.youtube.com/watch?v=dDU2JsgLpm4

what is the term for the effect where the sections start and continue to work independantly of each other?

submitted by /u/MattBlackG
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Can a known file be used to crack encryption?

Posted: 20 May 2017 05:45 PM PDT

With the "locker" viruses spreading around lately, I was wondering if having file with well known content, possibly very large, could be used to determine the code used to encrypt that file. TIA

submitted by /u/bobroberts1954
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[Geology][Physics] If we were to drill a hole that reached the core of Earth, what would happen?

Posted: 20 May 2017 04:15 PM PDT

Akin to electric field, does gravitational field store energy too?

Posted: 20 May 2017 02:30 PM PDT

How do LCD dispays work?

Posted: 20 May 2017 04:40 PM PDT

Is it true that one pound of body fat is equivalent to 3,500 calories?

Posted: 20 May 2017 03:57 PM PDT

How does rust affect a chrome spring?

Posted: 20 May 2017 11:19 AM PDT

I bought a grip strength trainer which uses (chrome) springs for resistance. It was secondhand and the springs are partially rusty inside: Picture

Does this weaken the springs and make them more prone to breaking or do I not have to worry about it as long as I get the rust off? I'm gonna put a lot of stress on them over time so I want to be sure here - if there's some concern, I'm going to send it back.

submitted by /u/Mithridates12
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When looking for test subjects for medicines they often ask for non-smokers. Don't they need to test how the drugs affect smokers?

Posted: 20 May 2017 07:07 AM PDT