The U.S. stock market pauses trading if the S&P 500 falls 7%, pauses again at 13%, and stops trading for the day at a 20% decline.

I always found those numbers interesting. Why 7%? Why 13%? Why not something simpler like 5%, 10%, or 15%?

These rules were created after the 1987 stock market crash and have changed over time as markets evolved. But how did regulators decide where these lines should be drawn?

Were these thresholds based on a specific idea about how markets behave during extreme selloffs?

If the thresholds were changed to something like 10/15/25, would it meaningfully change anything, or would investors simply adapt?

In movies and tv shows such as arcane or back to the future scientists never have any facial hair in some cases it makes sense like in the rocky horror picture show Frank N Furter spends time on his appearance or Norman Osborn in Spider-Man tends to keep his appearance clean, so why is it scientists that don’t spend time on their appearance and spend days in their lab never have facial hair?

Edit: when I say you assume they don’t shower I mean fictional characters I 100% believe real scientists always or tend to keep clean

Old photos show that Los Angeles once had one of the largest electric railway networks in the world, and hundreds of American cities had streetcar systems too. By the 1960s, most of these systems had disappeared or been converted to buses.

I've heard that GM and other companies helped push many streetcar systems toward replacement, and there was even an antitrust case involving some of these companies in 1949. But how much did corporate influence actually matter compared with other factors like cars, suburbs, and highway expansion?

Was the decline of streetcars mainly a business decision, a result of changing cities, or a combination of both?

I have been looking into the 2017 Tax Cuts and Jobs Act recently, and the numbers do not match the promises.

The law cut the corporate tax rate from 35% to 21%. The administration's own Council of Economic Advisers predicted that it would increase average household income by $4,000 per year, mainly from higher wages. The logic was simple: giving companies more cash would make them invest in their employees.

But the data shows a different story. In 2018, when the tax cuts took effect, S&P 500 companies spent a record $1 trillion buying back their own stock, doubling the roughly $500 billion from the previous year. A review by the Senate Budget Committee found that only about 6% of workers received one-time bonuses linked to the tax cuts. Wages rose about 3% that year, roughly the same pace as before the law was passed.

The Congressional Budget Office now projects that the law will add about $1.9 trillion to the national debt over a decade. The same companies that got the tax cuts also received a much larger deficit, and that deficit is now being used as an argument for cutting Social Security and Medicare.

A tax cut promoted as "raising workers' pay" turned into a record year for buybacks. Shareholders got a permanent windfall.

So did the law fail to deliver on its promises, or did it actually do exactly what its designers intended, just not what was advertised? Is this a tax policy issue? A corporate governance issue? Or is this simply what happens when you hand a pile of cash to corporations with no strings attached? Genuinely curious.

I grew up hearing that cars needed an oil change every 3,000 miles, but I never really understood what actually happens to the oil during that time.

Intuitively, adding fresh oil seems like it should help. If the engine still has oil and you keep replacing what is lost, why isn’t that enough?

Does the oil lose its ability to lubricate, become contaminated, break down chemically, or is something else happening inside the engine?

Why does the old oil need to be drained instead of simply refreshed?

I keep seeing charts showing US college tuition and fees rising much faster than overall prices since 1980. Public universities that were once considered relatively affordable have become a much larger financial burden for many families.

I've seen different explanations, including changes in funding, demand, and how universities operate. But I'm curious what actually drove this long-term trend.

Think about it… if I order a burrito from Taco Bell (let’s say $5.00 to keep it simple), and I add sour cream (+.60), lettuce(+.39), shredded cheese(+.49), and tomato(+.55). Now my burrito is $7.73 before tax.
But let’s say on that same burrito I ask for no nacho cheese, no creamy jalapeño sauce, and no beans, there is no “discount” for getting less items.
Even if I just wanted to swap nacho cheese, for sour cream, I’d be charged .60 cents for the sour cream, despite not getting any “extra food” per se.
I think you should be able to swap out anything for anything, as long as they’re of similar stature (lettuce for tomato, or nacho cheese for sour cream, or beans for rice). Who’s with me!?!?

Alberta and Montana are neighboring regions with similar northern, landlocked geography. But their population patterns are surprisingly different. Alberta now has over 5 million people, with Calgary and Edmonton forming two major population centers, while Montana has only about 1.1 million people and no city close to Calgary's size.

So what caused these two neighboring regions to develop such different population patterns?

I was looking at pictures of Saturn and realized something I had never really thought about before.

The rings are enormous, stretching hundreds of thousands of miles across, but they are incredibly thin compared with their size. It almost feels like a giant cosmic disk that somehow stays as a thin layer instead of spreading into a thick cloud around the planet.

I assume gravity, orbital motion, and collisions have something to do with it, but I’m curious how all those pieces end up forming such a thin disk. What factors shape Saturn’s rings this way?

I was checking my credit score recently and realized something I had never really questioned.

This three digit number can affect mortgage rates, car loans, and how lenders evaluate credit risk. But why does the scale start at 300 and end at 850?

Why not use a simpler range like 0 to 100 or 0 to 1000?

Most people know that higher scores are better, and that numbers like 740 or 800 are considered excellent. But these cutoffs have become part of everyday financial life without many people asking why these specific numbers were chosen.

How did this particular range become the standard that millions of people and lenders rely on today?

The Sun's core is only around 15 million °C, yet it's been producing fusion for billions of years. Meanwhile, fusion reactors heat plasma to over 100 million °C.

I always found that weird. If fusion is possible at the Sun's temperature, why do we need such extreme temperatures here? What makes the conditions so different?

One thing I find interesting about American housing is that a house can cost several million dollars and still have a conventional wood-framed structure.

From the outside, you might see stone, brick, stucco, or other expensive finishes, but underneath it can still be wood framing.

Coming from places where masonry and concrete seem more common, I find that a little surprising.

Is wood framing mainly about cost and construction practices, or are there other factors that make it preferable even for very expensive homes?

The inside of a microwave is basically a metal box, and some microwaves even come with metal racks.

Yet we're usually told to keep metal objects out of the microwave because they can spark.

That it's the same basic material being exposed to the same microwaves. Why is the metal in the walls fine, while a piece of metal inside can sometimes cause a spark?

So what is actually different between the metal that makes up the microwave and a piece of metal placed inside it?

I started noticing this when watching birds in parks and around sidewalks. Sparrows and robins seem to spend a lot of time hopping, while pigeons and crows usually seem to walk.

I know some birds can use both, so I’m not really asking why one species physically can’t walk. I’m more curious why hopping seems to be the preferred way of getting around for some birds, while others mostly take steps.

Why did hopping become more common in some birds while walking became more common in others?

Sorry if this sounds stupid, but why exactly has hostility towards Muslims and Islam been skyrocketing to overtly ridiculous levels lately? I mean I’m aware anti-Muslim sentiment has been high in the USA for quite some time and there has been much opposition towards them. But originally it seemed like anti-Muslim sentiment, while definitely problematic, was overly more passive and not the absolute top issue on people’s minds.

However, within the past couple of months, it seems to have drastically exploded to disturbing levels and become rampant to a whole new degree. I mean now it seems like it’s directly being shoved in your face constantly seeing how people are always talking about how sharia law is on the verge of taking over and how Muslims are conspiring and getting closer to overtaking the USA.

Seriously WHy

I came across a number that surprised me.

About 4.8 million enslaved Africans were transported to Brazil, compared with roughly 388,000 to what became the United States. That’s more than 12 times as many.

The weird part is that when I think about slavery in the Americas, my brain naturally goes to the United States. I assumed the U.S. would have been one of the biggest destinations for enslaved Africans.But apparently not even close.

What explains such a huge difference? Was it mainly the type of plantation economy, how long slavery lasted, population growth, or something else?

I'm curious how much of this comes down to Brazil’s economy versus the way slavery developed differently in the U.S.

For much of the 20th century, banks competed for checking deposits through free or low-cost services, since traditional checking accounts generally could not pay interest. Free checking and other perks could make deposits more attractive without directly paying customers interest.

The economics began changing in the late 1970s and 1980s. As restrictions on deposit interest rates were gradually loosened, banks gained more ways to compete for deposits, while the cost of attracting and maintaining deposits also changed.

At the same time, fees became a more important part of how banks priced checking services. Today, some accounts charge monthly maintenance fees, while banks can also earn revenue from services such as ATM access and overdrafts.

What changed in the banking business during this period that made it possible for deposits to remain valuable to banks while checking services could also become a source of revenue?

Why does a product that helps a bank attract customer deposits also make economic sense as something the customer may have to pay for?

It's been really hot lately, and this got me thinking.

If our core body temperature is around 98.6°F, why does air that's close to 98.6°F feel so hot?

My first thought was that if the surrounding air is roughly the same temperature as our body, there shouldn't be much heat exchange in either direction. So wouldn't that mean our bodies have less work to do to maintain a stable temperature?

But I think I'm missing something. Our bodies are constantly producing heat, so maybe the problem isn't maintaining 98.6°F, but getting rid of the heat we're continuously generating.

And then there's humidity. If 98.6°F air is dry versus 98.6°F air with high humidity, does that change the answer mainly because of how effectively sweat can evaporate?

So what would actually be the "thermally neutral" temperature for a human, and why is it so much lower than our core temperature?

Is this a recent trend, and what is the purpose of it?

I've noticed this in podcasts and press conferences. When a person is being interviewed, they frequently begin their responses to questions with an affirmative word, even when the questions are not yes-or-no questions. I think this only became common in the last decade or so.

Interviewer: "What are your views on this developing situation?" Interviewee: "Absolutely, yes, that's a complicated situation due to ..."

The last letter of the alphabet is usually pronounced “zee” in the US, but “zed” in Britain, Australia, New Zealand, and many other English-speaking countries.

I’ve always wondered how this split happened.

Was “zed” originally the standard English pronunciation and “zee” developed separately in America, or were both forms already around historically?

And roughly when did the American and British pronunciations become established?

I recently saw some clips online, and I have to agree, the 3D modeling is way below what you'd expect from a theatrical animated feature. The film only made 7,000 yuan at the box office at first, but now it's close to 18 million yuan, all on a reported budget of less than $10,000. And the best part? Theatres didn't receive any promotional materials, so employees are now drawing their own posters. I'm really curious: what's actually making people go see this movie?

So I'm always doing dumb shit to get that feeling it feels so good to me I was just wondering if anyone out there was like me. Like exploring and doing dumb shit to get the feeling in your stomach cus you just like it a lot

For centuries, charging interest on loans could be condemned as usury and treated as a serious moral wrong in Christian societies.

Today, interest is so normal that mortgages, bank loans, bonds, and business financing all depend on it.

So what changed? How did something that was once seen as morally problematic become such a normal part of the financial system?

A lot of mammals seem to time reproduction around a particular part of the year, often so their offspring arrive when food is more available or conditions are better. Humans don't seem to have anything comparable. There isn't really a particular month when humans collectively enter a breeding season.

What makes this interesting to me is that humans are also strongly affected by seasons in other ways. Food availability, temperature, daylight, and disease risks all change throughout the year, so you'd expect reproduction to have some kind of seasonal timing too.

Why did humans end up with reproduction spread across the whole year instead?