ELI5: Don't password rules actually make brute forces easier? They can eliminate all attempts that lack letters in a row, that don't have numbers, that don't have weird characters. Seems like these rules shrink brute force dictionaries?

Let’s play a game called “guess the outfit before you see the person”. Every time you correctly guess the right outfit, you win $500.

The judges of the game noticed that a lot of smart players would default to “jeans and a solid black T-shirt, black shoes, white socks, no hat and no jewelry” over and over again, and they won a bunch of times. Not every time, but enough times to make some money. A lot of people wear this outfit very much like a lot of people have common passwords.

The judges start making more rules both visible to the players and the people wearing outfits. Now you must wear:
-a hat of some sort
-at least one piece of jewelry
-socks that don’t match
-a shirt that has at least two colors
Amazingly, it became harder for contestants to effectively guess the outfits, even though it was made clear of the requirements for the outfit (or password)

To reflect brute forces, imagine if you were allowed to guess until you got it right, move onto the next person whenever you like. In order to maximize the amount of money you could make every day, you would make a list of the most common outfits(less people wear hats and jewelry than those who choose not to wear them, so you’d just focus on the most common stuff: shirts of various popular colors, blue jeans or khakis, shoes of various colors. Wasting time guessing anything more complicated probably won’t win more games than sticking to the absolute basics, especially if people don’t like wearing jewelry or hats because it requires more effort on their level when getting ready in the morning(annoying tedious task similar to memorizing symbols and which letter is capital)

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ELI5: Why are shows like Dr.Oz allowed to give out health advice that isn't scientifically supported? How isn't this considered illegal?

He’s not really giving out health advice. Instead, he protects himself by merely reporting what others say. He’ll never say “Alice`s itchy feet will be cured by eating dryer lint.” Instead, he’ll quote a study like this: “According to a recent study by the Home Appliance Institute, 57% of people who eat dryer lint say their feet do not itch.” So it’s the authors of the study making the claim, except not really. The study authors are going to say something non-committal like “Although a positive correlation was found between dryer lint consumption and non-itchy feet, more study is needed and it will be several years before the production of dryer-lint based medicines.”

Dr. Oz can also shield himself by interviewing a guest about the problem instead of making any statement himself. “What options are there for people with itchy feet?” “Well, a recent study …” So, you’ll have to go through 3 or more layers of people to finally find someone who didn’t really say your itchy feet would be helped by the dryer lint anyway.

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ELI5: Why people say "pardon my French" right before/after they swear?

In the early 19th century, intellectuals and those well-traveled would often drop French words into the conversation to show how clever they were. They would then point out that the word they had just used was French, often to embarrass someone nearby who was less fluent in the language.

To counter this, the less well-traveled (often poorer) people would, after swearing, loudly proclaim, towards those that had previously used French in the conversation, “Pardon my French.” - The latter stuck.

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ELI5:Why does something cold and smooth sometimes feel wet?

It’s been proposed that your body doesn’t in fact have “wet” receptors,
but instead combines temperature, texture, and pressure to perceive
“wetness” and form a sort of “touch memory” based on that. Have you ever
worn a latex glove, then dipped your fingers in water? Feels wet, but
your fingers are dry inside the glove.

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ELI5: What happens to your body when you stay up for more that 24 hours?

24 Hour Mark

The consequences of sleep deprivation at 24 hours is comparable to
the cognitive impairment of someone with a blood-alcohol content of 0.10
percent, according to a 2010 study in the International Journal of
Occupational Medicine and Environmental Health.

36 Hours

Now your health begins to be at risk. High levels of inflammatory
markers are in the bloodstream, said Cralle, which can eventually lead
to cardiovascular disease and high blood pressure. Additionally,
hormones are affected — your emotions can be all over the place.

48 Hours

After two days of no sleep the body begins compensating by shutting
down for microsleeps, episodes that last from half a second to half a
minute and are usually followed by a period of disorientation. “The
person experiencing a microsleep falls asleep regardless of the activity
they are engaged in,” she said. Microsleeps are similar to blackouts,
and a person experiencing them is not consciously aware that they’re
occurring.

72 Hours

Expect significant deficits in concentration, motivation, perception,
and other higher mental processes after many sleepless hours, Cralle
said.
“Even simple conversations can be a chore,” noted Kelley. This is when
the mind is ripe for hallucinations. Kelley recalled a time he was on
guard duty and repeatedly saw someone standing with a rifle in the
woods, ready to sneak into camp. Upon closer inspection, he determined
he was actually looking at a branch and shadows.

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ELI5: Why is it magically ok to blatantly steal someone elses song and make money from it, just by slapping the "cover" label on it?

You still have to pay a licensing fee to the songwriter to record a
cover.  However, there’s a clause in copyright law that provides for a
“compulsory license” for recording covers, which means that the
songwriter isn’t allowed to refuse, and the fee that you have to pay is
fixed.

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ELI5: Why don't we already know everything that's inside the pyramids?

Two people have answered that the pyramids are “incredibly complex”- they aren’t- they’re giant piles of rocks, with narrow shafts and a few small rooms inside. We know about those because the shafts reach the surface. There may be other rooms, but it would require tunneling through tons of rock to access them, because there are no doors or hallways to these rooms, and millions of tons of rock on top of them.

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ELI5: How does the Voyager still have power after all the years it's been in space?

Take two pieces of metal and put them very close to one another. Then heat one of the pieces of metal. The resulting temperature difference between the two pieces of metal generates a very small electric current.

Voyager 1, 2, Cassini, Galileo, Curiosity, and New Horizons use a small pellet of Plutonium to create this heat difference. The radioactive decay is what generates the heat. It doesn’t provide very much electricity but is extremely long lasting.

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ELI5: How does a touchscreen work?

There are several different types of touchscreens. The two that you’re probably most familiar with are resistive and capacitive.

Resistive touchscreens, which are used in Nintendo’s products and pre-iPhone PDAs and smartphones have flexible plastic screens. When you push on the screen, you squeeze multiple layers together and this completes an electric circuit.

Most modern smartphones use capacitive touchscreens. These touchscreens are made of glass. When you touch the screen with your hand, you distort the electric field in the screen and it can measure where that change took place. Insulators, like plastic or most fibers, won’t distort the field so the screen won’t recognize them. “Smartphone gloves” have metal fibers woven into the fingertips to make the screen notice them.

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ELI5: How does a computer know how long a second is?

Your computer has a slice of rock in it that moves back and forth when you run electricity through it. It counts the number of times it moves back and forth, and it knows how many times it moves back and forth in one second. When it has moved back and forth the correct number of times, it knows one second has passed.

-

To answer the single most asked question: When the power is off, there is a small battery on the motherboard that provides enough power to run the quartz timer, which is known as the CMOS battery. When that battery dies or is removed, the time will reset to a default value every time the computer loses power.

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ELI5: Why does multiplying two negatives give you a positive?

I give you three $20 notes +3 * +20 = +60 for you
I give you three $20 debts +3 * -20 = -60 for you
I take three $20 notes from you -3 * +20 = -60 for you
I take three $20 debts from you -3 * -20 = +60 for you

and quick note - the result is the gain or loss from where you started.

ANOTHER GREAT EXPLANATION BELOW

Think about it like this: If you film someone running forwards
(positive) and then play the film forward (positive) he is still running
forward (positive).

If you play the film backward (negative) he appears
to be running backwards (negative) so the result of multiplying a
positive and a negative is negative.

Same goes for if you film a guy
running backwards (negative) and play it normally (positive) he appears
to be still running backwards (negative).

Now, if you film a guy running
backwards (negative) and play it backwards (negative) he appears to be
running forward (positive). Even if you speed up the rewind (-3x or -4x)
these results hold true. Backward x backward = forward. Negative times
negative = positive.

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ELI5: What happened to needing "www" in front of an address?

Explaining like If you were 5:

You know when you send a package in the mail, you write the address and maybe, If the package is “Fragile” you’ll stamp “FRAGILE” all over it.
Why don’t you also stamp “NOT FRAGILE” on the packages that are not fragile? Because It’s implicit. If you don’t say anything the mailman knows It’s not fragile.

Same thing goes for the WWW. Since you can have multiple services on your domain (ex: ftp .address. com which means you want to share files; or mail. address. com which means you want to access the mail server on that domain) in the beginning you’d also write “WWW. address. com” to state that you wanted to access the HTML of the server.

As the web evolved and 99% of the average user wants to access the HTML version of the website, website owners no longer require you to type “WWW. address. com” instead, If you type “address. com” they assume you want to access the HTML version.

Just like you don’t need to stamp “NON FRAGILE” on your package, you don’t need to type “WWW”. Everyone assumes that’s what you want If you say nothing otherwise.

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ELI5: When my cat sits on my touch lamp, i can use his nose as an on/off button. How does this work?

With a touch lamp you can make a daisy chain / train of people. As far as it goes all the people will act as the touch surface. So if 10 people are connected to the lamp the 11th person will be able to use any part of the 10th person as a button ;). Similarly, if the first person is electrocuted so will all the rest. Just saying.

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ELI5: Why are the words "eleven" and "twelve," so different from the pattern of thirteen, fourteen, fifteen, etc?

This is one of those complicated etymology studies without an altogether clear answer.

Eleven and twelve are structures which show up in other northern-European languages, but the divide between using those forms and using the -teen form after twelve likely comes from the utility of twelve for trades-people.

Dozens and gross (144 or a dozen dozen) were preferred over tens for many trades for quite a long time due to their more convenient divisibility–evenly divisible by 2, 3, and 4–and this is the likely reason that the more continental European form survived in English. However, the evidence for any of it is very poor with conflicting theories even of the origins of the words.

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ELI5: Do dogs recognize that their name is their identity or do they simply know to respond when a certain sound is made?

Dogs are capable of recognizing their names, and discerning it from other sounds. Recent animal behavior studies have found that dog’s brains behave in much the same way our brains do when someone says our name. It appears that they are able to recognize that their name is not just another sound that someone is making, but is meant to specifically identify them.

Fun fact – cats have been shown to do this as well. The research suggests that cats can also tell when you’re using their specific name. The reason they often don’t react? They don’t care.

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ELI5: Why does light travel? Why does it not just stay in place? What causes it to move, let alone at so fast a rate?

Since this is ELI5, here is the really simple version without bringing spacetime into it.

The speed of anything is basically determined by it’s weight and the amount energy that is pushing it. You can push your toy cars really fast but if you try to push a real car it’s a lot harder. That’s because it weighs more. Light weighs nothing, so it moves at full speed all the time with no push at all.

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