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ELI5: Why is hand-made stuff "better" than machine-made stuff? by rnjbond in explainlikeimfive

[–]PlaneHijacker 9 points10 points  (0 children)

Answer the Bone-A-Phone

Assault on a Friendly Weapon

Backstroke Roulette

Baiting your Hook

Batting Practice

Bash The Candle

Beat Off

Beating the Bait

Beating the Bishop

Beating the Dummy

Beating the Snake

Beating the Stick (Please no more "beat")

Beating your Meat

Being your Own Best Friend

Bleed the Weed

Blow Your Load

Bludgeon the Beefsteak

Boppin' your Bologna

Buckin' it

Buffing the Banana

Buffing the Wood

Burping the Worm

Butter Your Corn

Calling Down For More Mayo

Calling All ***

Carrying Weight

Cast Off

Changing your Oil

Charm the Cobra

Choaking Charlie 'till He Throws Up

Choke Kojak

Choke your Chicken

Civil War

Cleaning out your Rope

Clean the Pipes

Clean your Rifle

Clubbing Eddy

Couch Hockey for One

Cracking the Fat

Crank the Shank

Cranking

Cranking For

Crank Your Cordiano (for Joe - the man with forearms like Popeye)

Crown the King

Cuff the Carrot

Cuffing the Puppy

The Scum

Custer's Last Stand

Date Miss Michigan

Date Mother Palm and Her Five Daughters

Devil's Handshake (Catholic School)

Diddle

Dishonorable Discharge

Disseminating

Doddle Whacking

Doodle Your Noodle

Do The Dew

Drain the Dragon

Drain the Monster

Drain the Vein

Dropping A Line

Dropping Stomach Pancakes

Firm Your Worm

Fist ****

Fist your Mister

Five Against One

Five Finger Knuckle Shuffle

Five Knuckle Olympics

Flogging Your Dong

Flogging Your Log

Flute Solo

Flying a Kite

Fondle the Fig

Freeing the Willies

Frigging the Love Muscle (British)

Gallop the Antelope

Gallop the Maggot

Getting In Touch With Your Manhood

Getting In Touch With Yourself

Getting to Know Yourself Personally in the "Biblical Sense"

Getting Your Caps Peeled

Giving it a Tug

Giving the John Hancock

Grease the Pipe

Greasing your Bone

Hack the Hog

Ham Shank

Hand Job

Hands on Training

Hand to Gland Combat

Hand Work

Having a Roy (Australian)

Have it Off

Have One Off the Wrist

Hitchhike Under the Big Top

Hitching to Heaven

Hit the Ham

Holding All The Cards

Holding Your Sausage Hostage

Hone your Bone

Hump your Fist

Hump your Hose

Humpin' Air

Ironing Some Wrinkles

Jack Hammer

Jack Off

Jackin'

Jackin' the Beanstalk

Jag Off

J Arthur Rank (British rhyming slang - )

Jazz Yourself

Jelly Roll

Jerk Off

Jerk the Gherkin

Jerk the Johnson

Jiggle the Jewelry

Jimmying your Joey

Killing the Beast

Knock the Top Off

Knuckle Shuffle on your Piss Pump

Launching the Hand Shuttle

Leakin' the Main Drain

Loping your Mule

Making the Bald Guy Puke

Making Nut Butter

Making Yogurt

Mangle the Midget

Manipulate the Mango

Manual Override

Masonic Secret Self Handshake

Massage your Muscle

Massage your Purple-Headed Warrior

Measuring For Condoms

Milking the Bull

Milking the Lizard

Milking the Monkey

Milkywaying

Moulding Hot Plastic

Nerk your Throbber

Oil the Glove

Oiling The Pogo Stick

One Handed Clapping

One Man Show

One Man Tug-O-War

Pack your Palm

Paddle the Pickle

Paint the Pickle

Pain the Walls

Pam Anderson Polka

Pat the Robertson

Peel Some Chilis

Peel the Banana

Peel the Carrot

Petting Your Dog

Playing With Dick

Playing With Susi Palmer and her five friends

Playing With Your Noodle

Play Pocket Pool

Play the Organ

Play the Pisser

Play the Piss Pipe

Play the Skin Flute

Play the Stand-Up Organ

Playing With the Snake

Playing Your Instrument

Play With Yourself

Pocket Pinball

Pocket Pool

Polish the Chrome Dome

Polish the Rocket

Polish the Sword

Polish your Bayonet

Polish your Helmet

Popping the Porpoise

Popping The Purple Pimple

Pound Off

Pound Your Flounder

Pound Your Piss Pump

Pounding your Pud

Pudwhacking

Pud Wrestling

Puddin'

Pull the Root

Pulling The Wire

Pulling Your Goalie

Pull Off

Pulling The Piss Pump

Pull the Pole

Pull the Pope

Pull Your Pud

Pull your Taffy

Pumping For Pleasure

Pumping For Power

Pump the Python

Punchin' The Clown

Punchin' The Munchkin

Punishing Percy

Punishing the Bishop

Ram the Ham

Ride the Great White Knuckler

Rolling The Fleshy Blunt

Roman Helmet Rhumba

Ropin' the Long Horn

Rope the Pony

Roughing up the Suspect

Rounding Up the Tadpoles

Routin' for the Yankees

Rub One Out

Rub the Unicorn's Horn

Runka (Swedish)

Scraping Your Carrot

Scratching the Itch

Seasonin' Your Meat

See Mrs. Palmer & Five Daughters

Self Love

Sending out the Troops

Shaking Hands With Abe Lincoln (Please - no more "Shaking Hands")

Shaking Hands With the Governor

Shaking Hands With Shorty

Shaking Hands With the Unemployed

Shake the Snake

Shifting Gears

Shine Your Pole

Shining The Helmet

Shooting Enemies

Shooting Putty at the Moon

Shooting Sherman

Shucking Bubba

Slam the Hammer

Slammin' the Salami

Slappin' Pappy

Slapping the Clown

Slap Boxing the One-Eyed Champ

Slap My Happy Sacks

Slap the Salami

Slapping the Cyclops (Please - no more "Slapping")

Slapping your Chub

Slinging Jelly

Sloppy Joe's Last Stand

Sloppy Sign Language

Stroke the Stallion

Smacking your Sister

Snap the Monkey

Snap the Whip

Snapping Your Carrot

Spank the Frank

Spank your Monkey

Spear Chucking

Spreading the Mayo

Spunk the Monk

Squeeze the Cream From the Flesh Twinkie

Squeeze the Lemon

Squeezing the Tube of Tooth Paste

Squeezing the Burrito

Staff Meeting

Stall Clapping

Stir the Soup

Stroke Off

Stroking It

Stroking your Goat

Stroke your Poker

Taking a Shake Break

Tame the Wild Hog

Tap the Turkey

Tease the Python

Tease the Weasle

Tenderize the Meat

The Erky Jerk

The Sticky Page Rhumba

Threading a Needle

Throw off a Batch

Throwin' Down

Thump the Pump

Tickle the Elmo

Tickle the Pickle

Toss Off

Toss the Boss

Toss the Turkey

Tugging your Toobsteak/Toobsnake

Tug of War with Cyclops

Tuning the Antenna

Tussle with Your Muscle

Unwapping the Pepperoni

Varnishing the Cane

Wailing

Walk the Dog

Walking Willie the One Eyed Wonder Worm

(British)

Waxing the Dolphin

Wax your Jackson

Wax your Weasel

Wax your Willy

Whack Off

Whack Your Tack

Whip the Dummy

Whip your Dripper

Whipping the One-Eyed Wonder

Whipping the Pony

Whipping the Window Washer

White Water Wristing

Whizzin' Jizzim

Wiggling your Worm

Winding the Jack In The Box

Wonk your Conker

Working a Cramp out of your Muscle

Working your Willy

Wrestling the Eel

Wring Out your Rope

Wring Your Thing

Yahtzee

Yank My Doodle (It's a Dandy)

Yank Off

Yank the Yodle

Yank your Crank

Alright team, Where's 'Massage your octopus' gonna go?

ELI5: Why do LED lights look jittery or like they're strobing when you look at them quickly? by chickencereal in explainlikeimfive

[–]Agouti 105 points106 points  (0 children)

I've not seen a mains LED light without a bridge rectifier on the wild yet (fortunately!) And I think they are probably pretty rare outside the really cheap and nasty stuff.

The reason being full bridge rectifiers are only a few cents each and it means you need half the LEDs for a given lumen output.

Edit: thank you for my very first gold kind stranger!

ELI5: If light moves at a constant speed, does it never need to speed up? How can it be instantly at 300,000km/s? by electricp0ww0w in explainlikeimfive

[–]neanderthalman 571 points572 points  (0 children)

Reality is a little weird sometimes.

One phrase I always use when dealing with light is ‘all models are wrong, but some are useful’

It can be useful to think of light as particles (photons) travelling from point A to point B. It can be helpful to think of them as waves in other circumstances. But even these two contradictory models don’t really accurately describe reality.

What is light? In the simplest terms, all that ever really happens is an electron over here wiggles, and some time later, an electron over there wiggles. That’s it. That’s all that’s really happening.

There need not be anything in between them. Don’t get hung up on whether waves or particles of light “exist” in a conventional sense -you can’t have a jar of photons. But the wave/particle duality of light and all of our models are useful in predicting when and where and how much that second electron will wiggle in response to the first. Some of that interaction (where and when) is best described by waves, and some (how much wiggle) is best described as particles/photons. But light really is neither.

Anything in between the ‘start’ and ‘end’ cannot be seen or measured - because as soon as you make a measurement in between, that point of measurement ceases to be ‘between’ and instead becomes the end point.

So let go of the idea of ‘traveling’ for light, at least in the sense that it implies that the light somehow exists in transit between electron A and electron B. It doesn’t really. One electron wiggles, and it makes another electron wiggle at a distance. We talk in terms of ‘traveling’ because it is useful to predict when and where the second electron will wiggle.

ELI5: If light moves at a constant speed, does it never need to speed up? How can it be instantly at 300,000km/s? by electricp0ww0w in explainlikeimfive

[–]jrallen7 9 points10 points  (0 children)

I'm not an expert in relativity, but I'll give it a go.

Gravity doesn't actually act on mass, it's more that objects that have mass cause the spacetime around them to bend, and the severity of the bending is proportional to the object's mass. Then when other objects move through that bent space time, the bend alters their trajectory such that they follow the curvature. Here's a pretty decent demo on youtube:

https://www.youtube.com/watch?v=MTY1Kje0yLg

Now, since photons don't have mass, they don't actually cause curvature of their own, but they are still subject to the curvature that other objects (with mass) cause. So while nothing would ever be influenced gravitationally by a photon, the photon is definitely influenced gravitationally by other (massful) objects. Hence why light gets bent around massive objects in space (gravitational lensing).

ELI5: If light moves at a constant speed, does it never need to speed up? How can it be instantly at 300,000km/s? by electricp0ww0w in explainlikeimfive

[–]PaulsRedditUsername 5951 points5952 points  (0 children)

I'm really struggling with massless particles. If it truly is 0 how can it exist?

It's very natural here on Earth to equate the word "mass" with the word "weight." In fact, in our everyday lives, we can usually get away with using the two terms interchangeably. A massive thing is also going to be heavy.

It's actually more accurate to define mass as "how much work it takes to push the thing down the road." Again, very similar to "weight," just a subtle distinction.

If I'm trying to push an elephant on roller skates down the road, and attain a speed of, say, 35 miles per hour, I have to do a lot of work.

I can either do this work all at once, maybe by firing the elephant out of a cannon, or I can spread the work out over time, pushing the elephant gradually faster and faster until the desired speed is attained.

Later, I can calculate how much work it took to get my elephant up to speed. (There are measurements for this stuff like joules and newtons.) In the end, I will find that, regardless of my method--either shooting the elephant out of a cannon, or slowly pushing it-- the amount of work required to reach 35 miles per hour was exactly the same. It takes a certain, specific amount of work to get an object of a certain mass up to a certain speed.

With a massless object like a photon, there's no work at all required. The photon does not have to "explode" out of its flashlight as though it was shot from a cannon, it does not have to gradually accelerate over time, it's already there. The "work," in a sense, has already been done.

ELI5: If light moves at a constant speed, does it never need to speed up? How can it be instantly at 300,000km/s? by electricp0ww0w in explainlikeimfive

[–]HasFiveVowels 196 points197 points  (0 children)

this might help. Just consider, while watching that, that light moves in a straight line. It also might help to realize that gravity is caused by both mass and energy - light does have energy (though, really, that doesn't matter in this context)

edit: if you don't click the link (because of RES or whatever), just jump to 1 minute in. I despise the "rubber sheet" analogy and at 1 minute in he introduces a non-rubber-sheet-based demonstration.

ELI5: Why do some fabrics get softer when they're washed a lot, while others get rougher? by Ladybugoleander in explainlikeimfive

[–]seebeedubs 1302 points1303 points  (0 children)

Professional costumer and textiles worker here. This is a fairly thorough and accurate explanation. I would also add that the motion that fabrics experience in the process of machine washing and drying also stretches, pulls, and contracts the fibers, and The tensile strength of the fiber as well as its flexibility determines how it reacts to those processes as well. The other factor in how a garment reacts to washing is what it’s made of and how it’s produced.

TL/DR: RTFM. If your clothes say machine wash, dry flat on the tag, follow those directions if you like your clothes.

In-depth explanation:

Natural fibers like cotton, linen, and silk tend to be more resilient. This is partly because they have already evolved to survive the elements like heat, cold, and water, and partly because they are fibrous in their natural state.

Synthetic fibers, like nylon, rayon, and spandex tend to have more give because of the elasticity of their chemical makeup, however as they are manufactured from plastic, their natural state is one of a solid or liquid, and heat tends to break down the artificial bonds which have made them into a fiber. That’s why your rayon or spandex garments will often recommend an air dry or low heat.

The method of production also has an effect on a garment’s resilience.

Woven fabric, which is made on a loom in the way we tend to think of fabric being made (right? I’m not the only one who thinks about this stuff? I am? Okay, moving on), tends to be much stronger, and have a lot less give. It is many fibers laid flat and woven across each other to produce a number of different patterns and textures, and tends to be very strong and not very flexible. Your dress shirts, suits, formal dresses, and curtains are all (probably) woven. This means it has very little give in the fit, and if the fibers move too much, they tend to break rather than stretch. This is why these garments often say Dry Clean Only, because the act of subjecting the fibers to the motion of the washing machine will eventually destroy the garment.

Knit fabric, which is manufactured in a number of ways, from complicated knitting machines all the way down to grandmas with needles, takes a single, impossibly long fiber and wraps it in and around itself to create a much more flexible texture. Most modern casual clothing, from your sweaters and leggings, all the way down to your t-shirts and sweatpants, is produced in this way, making it stretchy and comfortable. The directions on these garments have a wide range, but most are machine washable, with instructions on temperature and drying method being variable.

This is where the material comes in. The more synthetic fiber in your garment’s content, the lower its tolerance for heat will be.

The exception to this rule is garments made from yarn, like sweaters, hats, and scarves. Yarn is many fibers spun together to make one thick fiber that is used to make the garment. Now matter how natural the wool used to make the yarn, it still won’t tolerate heat and twisting well. Think of a fiber optics cable, where the individual filaments are soft and flexible, but you really don’t want to twist and bend the cable too much or you’ll damage its fidelity.

If you’re still with me, thanks for reading. This is one of my areas of expertise and I’m glad someone on the Internet needed it today.

ELI5: What does iOS do differently to Android for iPhones to only need 1-2 GB of RAM? by georgewho__ in explainlikeimfive

[–]xilefian 20.7k points20.7k points x4 (0 children)

Eyy I actually know the answer to this one (game & app developer with low-level expertise in power and memory management - lots of iOS and Android experience and knowledge).


Android was built to run Java applications across any processor - X86, ARM, MIPS, due to decisions made on the early days of Android's development. Android first did this via a virtual-machine (Dalvik), which is like a virtual computer layer between the actual hardware and the software (Java software in Android's case).

Lots of memory was needed to manage this virtual machine and store both the Java byte-code and the processor machine-code as well as store the system needed for translating the Java byte-code into your device's processor machine-code. These days Android uses a Runtime called ART for interpreting (and compiling!) apps - which still needs to sit in a chunk of memory, but doesn't consume nearly as much RAM as the old Dalvik VM did.

Android was also designed to be a multi-tasking platform with background services, so in the early days extra memory was needed for this (but it's less relevant now with iOS having background-tasks).

Android is also big on the garbage-collected memory model - where apps use all the RAM they want and the OS will later free unused memory at a convenient time (when the user isn't looking at the screen is the best time to do this!).


iOS was designed to run Objective-C applications on known hardware, which is an ARM processor. Because Apple has full control of the hardware, they could make the decision to have native machine code (No virtual machine) run directly on the processor. Everything in iOS is lighter-weight in general due to this, so the memory requirements are much lower.

iOS originally didn't have background-tasks as we know them today, so in the early days it could get away with far less RAM than what Android needed. RAM is expensive, so Android devices struggled with not-enough-memory for quite a few years in the early days, with iOS devices happily using 256MB and Android devices struggling with 512MB.

In iOS the memory is managed by the app, rather than a garbage collector. In the old days developers would have to use alloc and dealloc to manage their memory themselves - but now we have automatic reference counting, so there is a mini garbage collection system happening for iOS apps, but it's on an app basis and it's very lightweight and only uses memory for as long as it is actually needed (and with Swift this is even more optimised).


EXTRA (for ages 5+): What does all this mean?

Android's original virtual machine, Dalvik, was built in an era when the industry did not know what CPU architecture would dominate the mobile world (or if one even would). Thus it was designed for X86, ARM and MIPS with room to add future architectures as needed.

The iPhone revolution resulted in the industry moving almost entirely to use the ARM architecture, so Dalvik's compatibility benefits were somewhat lost. More-so, Dalvik was quite battery intensive - once upon a time Android devices had awful battery life (less than a day) and iOS devices could last a couple of days.

Android now uses a new Runtime called Android RunTime (ART). This new runtime is optimised to take advantage of the target processors as much as possible (X86, ARM, MIPS) - and it is a little harder to add new architectures.

ART does a lot differently to Dalvik; it stores the translated Java byte-code as raw machine-code binary for your device. This means apps actually get faster the more you use them as the system slowly translates the app to machine-code. Eventually, only the machine code needs to be stored in memory and the byte-code can be ignored (frees up a lot of RAM). (This is Dalvik, not ART). Art compiles the Java byte-code during the app install (how could I forget this? Google made such a huge deal about it too!) but these days it also uses a JIT interpreter similar to Dalvik to save from lengthy install/optimisation times.

In recent times, Android itself has become far more power aware, and because it runs managed code on its Runtime Android can make power-efficiency decisions across all apps that iOS cannot (as easily). This has resulted in the bizarre situation that most developers thought they'd never see where Android devices now tend to have longer battery life (a few days) than iOS devices - which now last less than a day.

The garbage collected memory of Android and its heavy multi-tasking still consumes a fair amount of memory, these days both iOS and Android are very well optimised for their general usage. The OS tend to use as much memory as it can to make the device run as smoothly as possible and as power-efficient as possible.

Remember task managers on Android? They pretty much aren't needed any more as the OS does a fantastic job on its own. Task killing in general is probably worse for your phone now as it undoes a lot of the spin-up optimisation that is done on specific apps when they are sent to the background. iOS gained task killing for some unknown reason (probably iOS users demanding one be added because Android has one) - but both operating systems can do without this feature now. The feature is kept around because users would complain if these familiar features disappear. I expect in future OS versions the task-killers won't actually do anything and will become a placebo - or it will only reset the app's navigation stack, rather than kills the task entirely.

ELI5: What does iOS do differently to Android for iPhones to only need 1-2 GB of RAM? by georgewho__ in explainlikeimfive

[–]dont_forget_canada 715 points716 points  (0 children)

I believe the true answer to this question is fascinating, and that it's actually just one piece in a bigger scenario (playing out right now that started in 1993) and that all of us are about to witness a transformation in the personal PC space that a lot of people wont see coming.

First, lets focus on why the history of apple as a company put them in the position they're in today where they build everything in-house and it seems to work so well for them. Apple has the upper hand here when it comes to optimizing the software and hardware in a way that Google can never have, because Apple is calling all the shots when it comes to OS, CPU design, and device design. Google doesn't have that luxury.

Google builds one piece of the handset (OS) and have to make it work in tandem with many other companies like Samsung, Qualcomm and Intel (for the radio). This is a very difficult task and is why OEMs like Samsung often have to also contribute a lot on the software side when building something like the S8.

The reason Apple is in this position (where it can control the entire hardware/software creation of the device) is twofold. On the one hand Steve Jobs always wanted to control the software and hardware aspects of the Macintosh because he saw that it made it easier to provide users with better UX this way, and also the more control he could exert over the users the better.

The other fascinating and often overlooked but incredibly important reason why Apple can do what they do with the iPhone has to do with IBM, PowerPCs and a little known company called P.A. Semi. You see, up until around 2006 Apple used PowerPC CPUs (by IBM) instead of x86 (by Intel). It is believed by most that Apple switched to Intel because Intel made more powerful chips that consumed less power. This isn't actually completely true. IBM is who made PowerPC design/chips and by the time 2006 rolled around IBM had sold off thinkpad, OS/2 had failed and they were almost fully out of the consumer space. IBM was completely focused on making large power hungry server class CPUs and here was Apple demanding small power efficient PowerPC CPUs. IBM had no incentive towards making such a CPU and it got so bad with Apple waiting on IBM that they ended up skipping an entire generation of PowerBooks (G5).

Enter P.A. Semi. A "startup for CPU design" if there ever was one. This team seemingly came out of nowhere and created a series of chips called PWRficient. As IBM dragged its feet, this startup took the PowerPC specification and designed a beautifully fast, small and energy efficient PowerPC chip. In many cases it was far better than what Intel had going for them and it was wildly successful to the point where the US military still uses them in some places today. Anyway, their PowerPC processor was exactly what Apple was looking for, which came at a time when IBM had basically abandoned them, and Apple NEEDED this very bad.

So what did Apple do? they bought P.A. Semi. They bought the company. So at this point if you're still reading my giant block of text you're probably wondering but if Apple bought the company who could solve their PowerPC problem, why did they still switch to Intel? And that's where the story goes from just interesting to fascinating: Apple immediately put the team they had just bought in charge of creating the CPUs for the iphone. See, people always ask when is Apple going to abandon the Mac? well the real answer is that they abandoned the Mac when they switched to Intel, because this was the exact time when they not only gave up but abandoned a perfect solution to the Mac's CPU problem, and where they instead re-purposed that solution to make sure that they never have a CPU problem with the iPhone.

So what lessons did Apple learn here? That if a critical component to your device (i.e. CPU) is dependent on another company then it can throw your entire timeline off track and cost you millions in revenue lost (the powerbook g5 that never happened). Apple was smart enough to know that if this was a problem for the Mac it could also be a problem for the iPhone. When a solution arrived for the Mac they instead applied it to the iPhone instead, to make sure there was never a problem.

And that team from P.A. Semi has designed Apples ARM CPUs for the iPhone ever since, and they're at least two generations ahead of the chips Android devices generally use, because they were first to market with a 64bit architecture, and first to allow the use of "big" and "little" cores simultaneously.

And as for Mac users? Well, the switch to Intel allowed the Mac to keep living, but MacOS now comes second to iOS development, and new Mac hardware is quite rare. Apple has announced plans for app development that is cross compatible with iOS and MacOS. Apple has started shipping new Macs along with a second ARM CPU. The iPad Pro continues to gain MacOS like features such as the dock, file manager, multi-window/split support. All signs point to MacOS being on life support. When Steve Jobs introduced MacOS he said it was the OS we would all be using for the next 20 years, and guess what? Time's almost up.

And the irony of it all is that history has now repeated: Apple now has the same problem they had with IBM, but now with Intel. Intel is now failing to produce chips that are small enough and that run cool enough. Apple will have to redesign the internals of the MacBook to support 8th gen chips due to changes intel made. Even the spectre/meltdown bug. The Mac is yet again dependent on a CPU manufacture in a way that harms Apple.

So yes, the iPhone is something to marvel at in terms of its performance. You might be thinking Android is the big loser here, but really it's the Mac and it's Intel. I believe we at the cusp of an event that will make the IBM/PowerPC drama seem small. In five years from now we likely wont even recognize what MacOS and Windows are anymore, and Intel will either exit from the portable consumer space, or they will have to go through an entire micro-architectural re-design and rescue themselves as they did in '93 with the Pentium.

In '93 Intel almost got destroyed because their CISC chips weren't as powerful as RISC chips such as PowerPC. Intel then released Pentium, which is essentially a RISC chip (think PowerPC or ARM) but with a heavy duty translation layer bolted on top to support CISC instructions that every Windows PC required. This rescued Intel up until right now but the industry has evolved and Intel's "fix" in '93 is now their biggest problem for two reasons: 1) they physically can't compete speed/heat/size with ARM now because they have to drag along this CISC translation layer that ARM doesn't need; and 2) Windows is about to introduce native ARM support with a software translation layer. Remember, Microsoft has the same CPU dependency problem that Apple has. And Microsoft's software solution allows them to throw away Intel for something better. Users wont notice the switch to ARM because it's transparent, but they will notice the 20 hours of battery life and thinner devices they get in the future once Intel is gone.

ELI5: What does iOS do differently to Android for iPhones to only need 1-2 GB of RAM? by georgewho__ in explainlikeimfive

[–]RusselsChoccyTeapot 2251 points2252 points  (0 children)

Oyy, you got the vowel wrong ;)

  • Eyy I actually know the answer

  • Ayy, awesome response.

ELI5: Why is having a high bypass ratio on a jet engine more efficient? by eazyvictor in explainlikeimfive

[–]mmmmmmBacon12345 13 points14 points  (0 children)

The core of the engine has very high speed exhaust, it takes a relatively small quantity of air and speeds it up to high speed. This is a large change in momentum for a large amount of energy

The bypass fan takes a large amount of air and speeds it up just a bit. This gives a large change in momentum but doesn't waste energy accelerating the air up to high speed.

Momentum is mass*velocity while energy is 1/2 * mass * velocity2 The engine core is giving the fan a certain amount of energy to work with, but thrust is determined by how much momentum it can impart not how much energy. Thus taking a huge amount of air and accelerating it a little gives the biggest change in momentum for the smallest energy usage

ELI5: What is so different about their pathways that causes aspirin to be useful in anti-platelet therapy and Ibuprofen to be a detrimental factor regarding heart disease? by Tellano in explainlikeimfive

[–]Iamnotthefirst 9 points10 points  (0 children)

ELI5: Imagine you are having guests over and there is a room that you don't want anyone to go into. If you simply close the door that's ibuprofen. If you lock the door and throw away the key that's asprin.

More details:

Both asprin and ibuprofen affect the production of compounds that contribute to platelet aggregation (clotting). The difference is that asprin is an irreversable inhibitor (locked door, no passsage because people can't open door) while ibuprofen is a reversible inhibitor (closed door, some passage if people choose to open door).

Answers to your specific questions:

1) Both drugs act on COX enzymes (COX-1 AND COX-2) non-selectively. This just means that they affect both COX enzymes not that they affect them equally - that's the key point. COX-1 and COX-2 work together to regulate blood clotting. COX-1 promotes clotting (platelet aggregation) COX-2 inhibits it. Main side effects of COX-1 inhibition tend to be gastrointestinal. Main side effects of COX-2 inhibition tend to be cardiovascular. I feel like that answers your questions but I'm going to ramble.

Asprin acts significantly more on COX-1 (anti-clotting effect), and does so irreversably. Ibuprofen acts on both to similar degrees, or at least not nearly as different as asprin, but reversibly. Inhibition of COX-2 is what is associated with cardivascular risk because you are removing the inhibition of platelet aggregation (basically making platelets more sticky so they clot). That's why COX-2 selective NSAIDs like Vioxx were pulled.

2) It is the difference between irreversible and reversible inhibition as well as the difference in affinity for each COX enzyme. Since asprin acts more on COX-1 its effect is primarily anti-clotting. Ibuprofen acts on COX-1 and COX-2 but because it's inhibition is reversible the anti-clotting effect is lower than asprin but the pain killing effect greater since it acts on COX-2 more than asprin.

The main adverse effects of both asprin and ibuprofen are gastrointestinal like ulcers, stomach bleeding, stomach discomfort and upset. These are caused by inhibiting COX-1. The cardiovascular side effects of ibuprofen are related to COX-2, which asprin acts less on.

ELI5: What is this major security flaw in the microprocessors inside nearly all of the world’s computers? by wariozero in explainlikeimfive

[–]zoox101 1797 points1798 points  (0 children)

There are already some great answers here, but this is a really important issue for everyone to understand, so I'm going to do my best to ELI5 it even further.

At it's heart, your computer works just like a library. It's constantly reading and moving information just like students read and move books. And just like any good library, your computer has a friendly librarian: Ms. Kernel.

Whenever you go to check out a book, you give Ms. Kernel the title and she goes to fetch it for you.

However, this library may contain some pretty secret stuff, so Ms. Kernel always checks to make sure you've got permission to read the book you're asking for.

Back in the old days, Ms. Kernel had to do all the work herself, and as you might imagine, it was painfully slow. However, recently we've gotten better at designing computers that can do multiple operations at once, meaning that Ms. Kernel now has a bunch of assistants helping her out. Yay!

This is great for the library, because now it can handle more people than ever before. However, it also creates a weakness that was only just discovered.

Here's how it works...

You, a mischievous ne'er do well, want to read Suzie's diary, which she keeps in the library. However, Suzie hasn't shared her diary with you, so Ms. Kernel won't let you check it out. So you decide to do something rather clever...

Rather than asking for the diary directly, you ask Ms. Kernel to do two things...

  1. Fetch Suzie's diary

  2. Fetch a book where the first word in the title is the first word in Suzie's diary

Now, back in the old days this wouldn't have been a problem. The first thing Ms. Kernel would have done would be to ask Suzie if you could read her diary. When Suzie said no, Ms. Kernel would have stopped.

However the assistants make things more complicated.

To save time, Ms. Kernel asks one assistant to ask Suzie for permission while the other goes to find the two books you asked for.

When the first assistant tells Ms. Kernel that Suzie said no, the second one gives her the books which Ms. Kernel sets on her desk.

Ms. Kernel tells you that you can't have the books. However, because they're sitting on the desk, you can read the titles. The first one's called "Suzie's Diary" and the second one's called "The Cat in the Hat".

Because you asked for a book that has a title that begins with the same word as the first word in Suzie's diary, you know that the first word in the diary must be "The".

If you wanted to, you could repeat this process for every word in the diary, until you could read the whole thing.

The problem with this exploit is that it works in every library that has assistant librarians, which covers just about every modern processor out there.

The only real fix is to force the assistants to run the check before fetching the books, which will slow down the library as a whole.

The biggest issue is that the parallel processing (assistants) is leaving the cache (desk) in a different state than they found it, even though the permission check failed.

Thankfully, there isn't any known malware that exploits this bug, but the safest thing to do is to update your devices as soon as a fix is released, to prevent then from being affected in the future.

The performance issue shouldn't be a major problem for most personal devices (small library, few assistants) but will likely cause a performance decreases on larger machines (i.e. university supercomputers).

ELI5: How do aged spirit brands(whisky etc.) that grow rapidly manage to have enough stock if everything is aged minimum 10 years? by SchmodSchmooper in explainlikeimfive

[–]TournantDangereux 12.5k points12.5k points x2 (0 children)

You avoid as much as possible, making your name on aged single malts if you are a new distillery and are interested in expansion.

  1. You distill and sell spirits that don't need to be aged for years. A new distillery can turn out rum and flavoured vodkas in short order. That pays the bills while your new-make spirit is aging and becoming whisky.

  2. You buy up whisk(e)y from other distillers, blend it, bottle it and sell it under your label. A lot of US whiskey comes from one very large alcohol distiller who sells a dizzying array of ages and flavour profiles. You blend these to taste, perhaps aging them for a few months in a finishing barrel and then sell them, with or without an age statement, under your brandname.

  3. You try to find interesting new-ish barrels in your rick houses and release a no age statement (NAS) whisky. Ardbeg does this a lot with their Committee releases and their routine NAS releases (Uigeadail & Corryvreckan). In Scotland, NAS whisky still has to be at least 3 years old, but 3 years is better than 10 years both for space management and mitigating losses to evaporation.

  4. If you are "reviving" a defunct distillery, you may be able to buy aged stocks distilled at your distillery in years past that are held by other distilleries and blenders. Bruichladdich was able to do this as part of the offer to buy and revive that distillery at the turn of the millennium. If you can come up with the money, there may be thousands of barrels of 10 year old whisky available from past runs at your "new" distillery.

Later, once you are fully capitalized, have adequate inventory, sufficient warehouse space and have some feeling for the market, then you can start focusing on aged single malt releases. Those are some the most restrictive constraints though, so you generally want to avoid locking yourself into those while you are still raising capital and getting established.

ELI5: How do Adaptive Optics know how to correct for atmospheric distortion and give us Hubble-quality images from a telescope on the ground? by Shattered_Sanity in explainlikeimfive

[–]larryobrien 187 points188 points  (0 children)

First, there's the basic concept: the atmosphere distorts the light in the same way that a rippling surface of water will distort what's beneath. If you can physically distort a mirror such that it cancels out those ripples, you get a vastly sharper image at the imager.

You can figure out the distortions that are present by looking at how a point source such as a star is distorting. Most targets are "faint and fuzzy" and require very long exposures for enough photons to collect in the pixel sensors to produce data. So you cannot generally use the target as the point source. If there happens to be a natural star that's close to the target in the field-of-view, you can do AO on that. ("Natural Guide Star" NGS.)

But since the FOV is quite small, often AO involves shooting a laser into the sky. There is a layer in the atmosphere about 90Km up that is rich in sodium atoms. A laser that produces a 589nm light (a shade of yellow) at about 15-20W (which is a lot!) is directed into the sky alongside the target. Traditionally, these have been single point-source but a new generation of "multi-conjugate" AO systems are coming online that have multiple lasers (the artificial guide stars they produce look like the "5" pattern on a 6-sided die).

So these "artificial guide star(s)" are your point-source that are rippling according to the atmosphere. You insert a small pick-off mirror into the light path and direct the AGS image into a "wavefront sensor" (WFS). I'm going to hand-wave a little and just say "this measures the ripples / distortion and calculates the necessary corrections at about 1000 times per second." (/u/tatsuling does a good job explaining this in his answer.)

The corrections are sent to a "deformable mirror" that is downstream in the light path. The deformable mirror corrects the distortions and bounces the light into the instrument. (Fun fact: pretty much all the mirrors in the instrument are deformed at various frequencies to correct for gravity, vibration, etc. They're really amazing dynamic systems.)

How good is AO? Gemini Observatory's multiple-lasers GeMS instrument can produce "angular resolution (the size of the smallest detail that can be resolved) of 0.04 to 0.06 arcsecond over a field of 85 arcseconds squared, which significantly beats the typical resolution in "seeing" limited (non-AO) conditions of 0.5 arcsecond at good astronomical sites."

P.S. If you've returned some of your Christmas gifts for credit, you can buy yourself a kit: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3208

ELI5 why does the human body go into a "coma" and what is the body doing during this period? by PlataDePablo in explainlikeimfive

[–]Wordpotatosalad 51 points52 points  (0 children)

Sorry, this isn’t right...

In terms of the original ELI5:

Your brain is like a delicate machine, which needs a lot of things to be just right for it to work properly.

It needs things like oxygen, sugar, salts & minerals. It needs to be the right temperature. There shouldn’t be any drugs interfering with it.

If any of these things, or others, are wrong, then the brain won’t work properly, like a machine can malfunction.

One way it can malfunction is the bits that let you consciously think and feel might turn off. This would be a coma.

Edit: in terms of the questions about a ‘medically-induced coma’:

Sometimes, we might need to make patients unconscious on purpose.

This is common if patients need an operation, because it might be unpleasant for them to be awake during it, and because we need them to keep very still. This is a general anaesthetic.

Other times, someone might be so poorly that we need to make them unconscious. This is common if their treatment is unpleasant, like being on a breathing machine. It is also common if their brain isn’t working properly at the time, and they are very aggressive or agitated, and we again need them to keep very still.

Finally, sometimes if the brain is very damaged, we can put patients to sleep to help protect it - the brain uses less oxygen and other fuels when asleep, so it is less likely to be damaged if levels of these are low.

There are lots of medicines we can use to put people to sleep. They generally work by preventing signals from travelling in the brain normally, like turning off the WiFi connection to your computer. We can put people completely to sleep (a general anaesthetic), or just make them very sleepy (sedation).

Hope this helps!

Edit 2: thanks for the gold (I think that’s what the symbol means on Apollo..)!

Source: I’m an anaesthetist & ICU doctor.

ELI5: How does a phone can measure blood pressure and heartbeat with camera and flashlight? by zell-88 in explainlikeimfive

[–]AromaOfElderberries 2 points3 points  (0 children)

The camera monitors the color of the light that is diffused back out of the skin. From that, it can tell blood gas concentration in much the same manner that the little dingus they put on your finger at the doctor's office.

As blood moves through the capillaries, it is constantly refreshed, and the light changes color rhythmically.

It can't really tell blood pressure from that. Just pulse and O2 saturation.

ELI5:Can somebody explain the class divisions in England/UK? by dukenotredame in explainlikeimfive

[–]Hubble_Bubble 803 points804 points  (0 children)

I have to laugh at all the people saying ‘class divisions don’t really exist here any more’. My life has been a study of British class divisions. My family went from lower working class (both grandfathers were coal miners) to the lower rungs of aristocracy in two generations (my sister and I were privately educated, went to very good universities; she married name-on-buildings wealthy). I can safely assure you that class divisions are very deeply entrenched in the UK, but not in a glaringly obvious way to most people.

The working and lower-middle classes are relatively close together in wealth, education, society, location, etc. They intermingle pretty seamlessly, having gone to the same state schools, holiday destinations, restaurants, rugby/football games, pubs, etc -and in some cases universities. The major fork in society is found at true middle-class, where those who can afford it send their children to private schools.

This is the most obvious indicator of class and wealth. ‘Old money’ places like Eton, Harrow and Gordonstoun (expect titles and landed gentry), newer money but still very wealthy places like Charter House and Cheltenham Ladies’ (father is a CEO, CFO, Russian property magnate, mummy comes from old money), moving ‘down’ the ranks to Haberdashers’, Houndslow, etc. until you find yourself among the thousands of ‘no-name’ private schools that, despite not possessing massive endowments or educating peers of the realm, still act as the gate-keepers of social stratification.

Universities are slightly more egalitarian. Theoretically, anyone can make it to Oxford, Cambridge, UCL, St Andrews, etc. if they work super hard and have all the right extra-curriculars, but state schools capable of sculpting such a student are relatively thin on the ground (and generally located in high net worth areas anyway). In comparison, private schools exist to craft you into the perfect candidate. If a state school student does manage to make it to the British version of the Ivy League, they are immediately met with their first taste of social stratification: drinking port with tutors, rowing, lacrosse, punting, literal Old Boys’ and Girls’ networks, wine tasting, ski trips, gap years, summers abroad, polo, and so on. Having never experienced these things, it is very difficult to assimilate and learn the new language of wealth and privilege, even if you can afford to indulge such pastimes.

Upper-middle and upper class people don’t apply for jobs. They reach out through the previously established networks described above, secured and reinforced by a lifetime of shared experiences on their strata.

It is because of these literally exclusive experiences that the wealthy have their own language that distinguishes them from middle-class in a way that doesn’t ‘upset the proletariat’. Your average Brit wouldn’t be able to distinguish a casual mention of skiing in Corchevel from Klosters or St Moritz or Val Thoren, but these all mean different things to the initiated. The working and middle classes would just hear ‘I went skiing’; something that most can not afford to do either way. But to those in-the-know, these make a difference between networking with millionaires and networking with billionaires. This is just one example out of dozens to show how the upper-classes heavily stratify themselves in ways the lower classes aren’t privy to.

Where you shop, dine, drink, live, work, entertain and are entertained, holiday, golf, swim, play tennis, etc. mean little to those who don’t know the language, but everything to those who do.