Like every tech, the concept is “we can just win every golf trophy by doing every hole in one shot”

But then you shoot and miss and you realize you forgot the wind, the grass type and so on.

Most technologies are not about getting from A to B, but going from A to B without stepping on some dog poo.

For example, at this level a spec of dust can totally destroy your chip or even your machinery. So you may start your journey thinking about chips and now you have a department that develops vacuum machinery, another department developing air cleaners that stop nano dust, and another developing optical lenses… and your final product is only as good as your “side quest score”. And every side quest opens new side quests.

I remember an architect saying:

The bridge is 20% a bridge and 80% how to put it there.

There are several ways, but can be grouped in:

Remove the water, literally temporarily reroute the river.

Redirect the water: build a dam around the future pillar location, drain the spot.

The floor is lava: rework the ground on the two sides to make it firm enough to place massive equipment, from which you launch the premade bridge over the gap.

The floor is lava but old school: you build a lightweight wooden/whatever bridge from the shore into the river, join with the same structure coming from the other side. Use this structure as a platform on which you build the bridge.

The pointy stick: you stick giant sticks in the water and put the bridge over those sticks.

The suspended thing: you build a cablecar-like thing, from which you deploy wire after wire until you have a “golden gate”thing. Then from those wires you work your way down to build the road part.

Ice is your friend: stick pipes in the water, run coolant in the pipes and create an ice wall. It can be done to help in any of the above methods, where applicable. Even to freeze the terrain to prevent water to filter into a hole/excavation/whatever.

In all cases, the problem is not being under water, most construction hate water or hate being jointed in water. So even if you are the chief of the scuba planet with millions of scuba soldiers, you probably want the structure to be built in a dry environment. Then you can flood part of it, but only after it’s assembled or cured.

The above methods can be mixed in many ways.

The problem was the horses were naturally smaller than the ones we artificially breed later.

So unless you happen to be in a place where horses are naturally big, you would look like a total idiot going around on a struggling pony that will have a broken back very soon.

Still totally possible there was an area where horses could grew stronger due to climate and people did profit of it way earlier. I mean, if 5000 years ago was possible, maybe it happen even earlier than 5000 year ago if there were big horses not man-breeded.

In Italy we call them “battiscopa” which means “broom guard” and that’s what it does. When you mop or broom the floor you need to work close to the wall most time because it’s where most of the dirt is.

Now, without “broom guards” you will stain and damage the wall during time. “Broom guards” can be replaced easily and at a way lower cost than a wall repair. Bonus point, you can repaint stained “broom guards” without having to repaint the entire wall for consistency.

Iron loves to incorporate stuff. Problem is that it tends to make small-ish crystals of iron surrounded by a coating of stuff.

Imagine the iron crystal is used chewing gum, and the stuff is sand, then your material is made of dirty used chewing gum balls sticking one another with sand reducing the stickiness.

The cheapest form of iron ally is cast iron, with a lot of carbon. Works like your chewing gum balls with a hard coating on each grain. It’s strong but brittle as you can break apart the grains by breaking the hard brittle coating between the grains. It’s still good for casting, but can’t be bent into a shape, or forged into a shape.

If you reduce the carbon amount you can thin the brittle coating of grains. Needs more processing. More cost but better iron. Still brittle-ish, a further process is to add some material that softens both the grain and the coating. Medium strength, but ductile enough to be shaped. It’s the iron you see for general low cost purposes.

If you process more you can remove the carbon, now you have the good steel.

The good steel then can be tweaked. One way is to heat it up until the coating melts and is dissolved in the grain, then quench (fast cooling) and you have “frozen” the structure into a grain with thin/nonexistent coating and the dirty stuff dissolved in a harmless way int he grain. Do this with carbon steel and you have a good sword or tool. Some processes allow to add carbon to the surface only, so when you quench you get a strong flexible core and a harder surface that resist abrasion, good for blades, gears, tools.

Another process is to add very strong things to the coating or the grains or both. Chromium, molibdenum, vanadium, and so on. This way you get “super steel”. It’s quite expensive but according to the mix, you can get something very strong and flexible to make springs. You can get something just strong, hyper strong, usually to make spanners, tools, and expensive mechanical parts. There’s special mix that can give the grains a “skeleton” and an armor as a coating. These last category can be used to make drill bits and similar cutting tool, able to cut almost as Diamond.

The fascinating part of iron alloys is that it’s a material that loves to mix with a lot of stuff and loves to change grain size and shape and grain coating thickness, or even having no grain coating, all of this for each mix and each temperature, and iron also can be “frozen” in its structure by quick cooling. So it’s one of the few metals that can be mixed, heated to a point it gets a special grain, then “frozen” in that state.

I think I spent 3 moths at school to learn the most common (but not all) iron alloys, while it took just a month to discuss ALL the other metals. That’s how much you can play with iron alloys.

Main factors:

1 Engine noise: you want the engines to be away from the people. Having them in the tail is a good solution.

2 Structural weight: above a certain size, you gain a lot by optimizing the aircraft structural load. Engines and fuel are heavy. Having fuel and engines strapped to the wings means they are directly supported in flight. On the contrary, if you put the engine in the tail, the wing has to support the fuselage that then supports the engine, which asks for more structure, so more weight.

Conclusion: as long as the plane is small enough, tail engines are more silent and not so heavy. On bigger planes wing engines allow for a lighter structure, and due to dimensions, noise-wise they are still far enough from people.

Perks: wing engine are closer to ground and this saves a lot of maintenance time, and increases maintenance quality (the more comfortable is the technician, the better he can check things)

-source: I’m an aircraft mechanic (but not the designer, so take this with a bit of salt, design is not my job, shouldn’t be my job, damn I hate when I have to decide where to put the engines myself, that’s a red flag for the company)

For snowboard you want a helmet with no holes, and ear protection, even when hot, snow will get in ears and is a pain, also snow melts so if it gets in holes it makes your helmet wet inside. Nice to have is a short one inch front ledge, if you are landing on your face that bit will hit the ground before your nose, I purposely turn my head into the fall to make it happen. Better a hit in the higher part of the face and helmet than landing jaw or nose first, is as bad as it sounds. It needs to be shaped in a way that doesn’t impede your goggles, no sun shader so you have a better field of view upward, in some jump tricks you need to look upward. Need to stop hits on ice at high speed and slide, smoother helmet surface is better. Hits come from any direction, including the rear of the neck, so the helmet cover the sides and the rear a lot. Finally it’s likely to be fitted with a plastic clip in the back to retain your goggles strap so when you hit hard goggles don’t fly away.

For bicicle you want a lot of holes to cool you down, nothing blocking your ears cause that’s where your sunglasses sticks go. Sticks go outside the helmet lace cause it harms less if you fall. Need big long sun shade so the sun won’t cause reflections on your sunglasses, you will not need to look upward aniway. But left-right it need a to give a good field of view. Need to stop car hits for life saving purposes, no need to protect the face as yo are not looking for continuous hits. Instead, it’s focused for the centerline hits, front, top, upper rear. Its way deeper in protection compared to a snowboard one.

For downhill bikes you want a full face helmet because tooth and face surgery is expensive. It needs to stop the big hits but also prevent the continuous face scratching done by tree branches, and light hits to the ground in light falls. It is generally designed to be connected to neck protection too.

To close it: street bike helmets can be one shot, you hit, you discard the helmet. This allows lighter and softer designs, and a in depth protection; that single hit will hurt less that in a reusable helmet. Most extreme sport helmets can retain shape after multiple light hits. If I had to replace the snow helmet every hit, I would be broke. This comes at the cost of the helmet being a bit more rigid, giving less comfortable, sharper hit feeling, and more weight.

Personally, I find very difficult to massage myself, let’s say I want to relax my legs: Mi have to stiffen my arm to apply the pressure, then my chest and abdomen and push onto the leg. It’s very difficult to let the leg relax while the rest of the body is stiffening. If you don’t relax the part of the body, the massage won’t penetrate the first centimeter of the body. Muscles must be relaxed in order to let the pressure go deep.

Plus all the right things o saw in the other comments.

Still, self massage is possible but the best way is to use objects and rest your weight on them.

Matter can be divided in Newtonian:

Solid: can’t flow, can’t be compressed*

Liquid: can flow, can’t be compressed*

Gas: can flow and be compressed.

Fluid is anything that can flow, eg gases and liquids

Non Newtonian materials are generally man made materials that “cheat” and behave in a way not strictly in one of these groups. The most common are for example padding for body protections, a sort of rubber like material that can flex with your body but stiffens when hit. Very handy as it feels like clothing but protects like a solid pad. Another example is wet sand or mud, as a whole, it does not behave like a classic solid or a classic liquid.

*compressed in the sense that if you give infinite room, the gas will take all the room, and if you change the space it is confined, it will evenly be squeezed in it. Non compressible means that if you try compress the material, it will change its volume by very very little and oppose a lot of resistance to it.

These categories are broad and used for broad description. There are applications in which you can force these categories of material to do weird things, in extreme circumstances. For example, air at supersonic speed is not compressible, or better, does not behave like a compressible fluid.

Ty, corrected. I skipped that cause I wanted to keep it short. I work in aviation and if I open my mouth about corrosion it can take few hours before I shout up again XD

Let’s put it like this:

It is abundant… but…!

But it’s one of the metal the loves the most to oxidize and react with all sort of things in nature. Once you make it pure, it stays pure and does not corrode past its surface, In nature however, it is four mixed with all sort of things to which it loves to stick.

So the process of getting new aluminum requires to melt and process a lot of rock, discarding the most of it and keep some aluminum oxide. This requires to melt a lot of stuff. Then you have to convince that oxide to let go the oxygen it loves to stick to, so you can get pure aluminum. This requires a lot of electricity.

Basically finding aluminum is not an issue, but the amount of energy needed to purify it (read it as coal, gas, oil to burn to get that energy) is very big.

Let’s chose as reference the a point on a road. And let’s accelerate a car. I assume you know the equations. Let them assume we use the car’s engine to generate the force, and this engine is a combustion one, and we never shift gear, fix gear ratio.

We start the reasoning with: Speed = time * force / mass.

It happens that the car will travel faster and faster while accelerating, covering more and more distance per second. Distance=time squared * force / mass.

I will keep using force/mass as a substitute for acceleration.

Now, let’s say you push ed the car with 1000force, for 1000 distance, it will get to 10speed. To get the same car to the speed of 20, it will take twice the time.

But how much distance it took? To get to 20 speed instead of 10 speed, we will need twice the time. Again, distance=time squared*force/mass. So we will cover 4 times more distance as 2time squared is gives 4time as a result.

Breaking it down to the combustion in the engine, while the car gets faster and faster, the engine spins faster and faster, burning fuel faster and faster. There will be a fix ratio between engine and wheel, for each revolution of the wheel there will be a fix number of combustion cycles, all burning the same fuel. Pause it at any point of the travel: you can see for each meter of road, you burn a fix amount of fuel.

If getting to twice the speed covers four time more road, therefore burning four time more fuel.

This means the car has received 4 times more energy to get to 20speed compared to the energy it takes to get to 10speed.

From energy pov, the time it took doesn’t matter, what matters is what you burn to get there and for how much distance you had to burn.

The car’s kinetic energy is nothing else that the burned fuel energy. And the amount is determined by how much force for how many meters It traveled under that force.

To recap: kinetic energy=“fuel used” to get the object to that speed.

(speed=force * time /mass, transform this you have:

force= speed * mass / time.

Distance= speed * time)

SO HERE WE ARE: Kinetic energy = “fuel used” = force * distance = (speed * mass / time) * (speed * time) = speed * speed * mass / time / time= mass * speed squared

Hope this example helped visualize it. The rest of your question is answered just by changing the reference point. Law applies the same.

Can you explain the cancer part? I recall that’s why it is way easier to use them on animals as the cancer risk is “less of a problem”.

I’m pretty curious, if you have the time, I thank you a lot.

A wolf can eat as much as it can and go on hunting the next prey. The day it is too fat to catch the prey he will skip the lunch, and this keeps a wolf as fat as possible while being always fit enough to hunt.

If you take that wolf and give it unlimited food it will eat until it dies.

You are the same. Problems are:

1 your heart can’t pump blood to feed the gigantic muscles you need to move your fat around. Your heart will soon or later collapse for fatigue.

2 fat piles up in your blood too, and can clog your arteries. This can give enormous pain when a clogged artery stops feeding some tissue, and that tissue dies. But this can happen to organs too. It can happen to your brain or heart with fatal results.

3 kidney & liver are sized to keep your body clean, if you increase your body size too much they won’t keep up properly. Long term diseases will come.

4 you rot. Yea your tissue needs blood to live and if you are fat enough to not move enough, some parts will simply be compressed onto the sofa, receive too little blood, die and rot. Skin is one of the most likely early part that will die and rot.

5 you can’t run. There may be a fire or some other hazard and you can’t simply escape.

6 good news, fat floats better than bones so you won’t drawn easily at least. Also you can resist cold a bit longer.

Basically, cars and trains have a simple autopilot rule: if things go south, brake, stop, wait for instructions.

Planes simply can’t be told to pull the handbrake and wait rescue. The airplane crew is a very well dressed rescue team.

(Drones don’t count as they won’t carry people, so you can apply the rule if things go south “soft crash in the place you took off from”, which is nice but it means strike a power cable on the way to the soft crash or land on a person head, and in fact, you’d hood let the drone take off place completely free for emergencies. Real life personal example: Dude sent his drone from a parking lot, and the drone came back for an emergency, I was parking in that spot, if I came a little earlier that drone would have landed on top of my car. Now imagine two airbus 380 emergency landing on the same runway at the same time. If you make it simple they gonna crash one in the other, if you make it more complex you increase the point of failure of the machine and autopilot… ultimately, the more you try to code different scenarios the more new scenarios you open in an infinite spiral. Then you are back to the old set brakes and wait, which a plane can’t do). Or you use a human pilot so multiple pilots on multiple planes can adapt and sort it out.

Yes and no.

It depends on what the plane speed, what direction you fly and if you are far or close to equator.

But sure, you can fly west and see continents passing below you while you stay always in daylight or night or whatever. You can easily fly as fast as the earth rotation (1000mph at equator, less and less towards the pole where it’s zero) meaning you will see the sun always at the same angle to you while they planet below you revolves.

This happens only if you fly west as you are chasing the sun going west. To land at exactly the same local time you need a very fast plane, maybe supersonic, or take a route in a northern region with a normal jet (works also south but there’s no destinations close to the South Pole to try this trick for cheap). For example Toronto-Vancouver is 5 hours of flight, and only 2 hours in local time. Meaning you lost your race with the sun but slightly, considering those 5 hours include the plane moving in the airport, you probably lost one hour out of four spent in actual flight. Similarly, London-Vancouver is 9:45 hour flight and 1:45 time difference, quite close to see the earth rotate below you while not moving relative to the sun.

You just need to match the earth rotation speed in your area. Which again can be between 1000 and zero mph. Altho standing still in the North Pole is a bit of a cheat.

Is effective.

A bear can smell food even if properly packed. But let’s say the smell of the at food is 10 times less, that’s the difference between drawing any bear to you in a radius of 1 km or 10 km.

The math may not be exact but I hope you get e point. If the smell is kept small, you basically alert the bears that are close enough to be encountered anyway.

As most topics, prevention does not guarantee success, but meeting one bear that happens to be close enough every 30 hike you do is way better than meeting a bear every hike.

Most importantly, never feed animals. You teach them human=restaurant. Imagine next time you get invited to a restaurant everyone gets food except you… you get angry, do you? Imagine how angry a bear gets being fooled that way.

Like throwing a cigarette into kerosene, one degree less and it’s all fine and one degree more goodbye room.

If you happen to go in a relevant museum, keep an eye to tools and fire related inventions. Ancients spent their whole life with fire and they did that for centuries. It’s impressive the amount of tricks they came up with.

A nice trick is to light a fire in a mine level above the working one, the fire updraft and fumes do escape from a vertical shaft purposely built on top of it, the updraft sucks air form the levels below.

You need to arrange it with doors so you can force the fire to suck from the area you like and the outside air to be sucked in the level you want.

But that’s a method doable even at Stone Age tech.

Idk if gas pockets were common, as, ancient digging was superficial and by the time you get the tech to dig further down I imagine they got the tech to protect themselves. In between these two era they just died. I mean, there’s plenty of mine horror accounts from the 1700-1900. The whole industrial era was a gigantic trial and error thing. I remember industrial ventilation devices like hand operated, animal operated, and later steam operated air pumps, and acetilene lamps made “flash proof” to an extent. Problem is, if you get to a gas pocket, even if it doesn’t ignite, you are still really dead. There is no way to replace that much gas with fresh air in time. Having a bird that dies earlier than you is a good warning system, but to escape you have to climb a lot and climbing with little oxygen is not an endeavor that is famous for its success rate. To conclude, early ventilation systems were more about getting enough air to breathe and evacuate the lamps fumes.

They don’t. A developed country does not need to keep growing.

A country that made debt needs to keep growing.

Usually countries make huge debt to buy infrastructures, invest in research, or education. This fields are very expensive but are what make you progress. Making debt for this is an investment in the country’s future. The problem is, you have to pay back the debt. Developed or not, if you make a debt and fail to progress, you will not get the extra profits to pay back the debt.

The fact that developed countries are also in debt, is a circumstance. A coincidence. Poor countries also may have a big debt, and same as developed ones, they have to grow to pay back the debt or end up more in debt.

It’s due to bad laws and information,

There is no set threshold or measure, all we get is “can” or “cannot” give cancer. And to be fair, bottle water can give you cancer.

The point missing in our information system and regulation system, is to give a measure to it. Like, bottle water causes cancer but it would take maybe 500 years on average to develop one. If you are still alive at 100+ years, I bet back pain is still a bigger issue than water cancer.

Whatever you cook until brown/black Is cancerous. But how much? If you eat overcooked steaks only, you will still die of other complications before colon cancer. You need to strike a good balance of bad food and good food to live long enough to care about colon cancer, then worse case it’s still less likely than a car crash.

So, ok, things can harm you, you should avoid them, but the information is a bit on the clickbait/boogeyman side. Which helps no one to make good decisions.

For comparison, something cancerous like asbestos, has a cancer rate of 10% of the people working sometimes with it, and almost 100% of the people working with asbestos the entire life AND being smokers. That’s pretty scary.

Cigarettes alone are not reaching a 30% cancer rate. In a lifetime.

Alcohol gives other life threats well before reaching cancer level.

Steaks? Way less a killer than air pollution.

You should worry about steaks a bit less than getting a flu or malaria. idk you, but I don’t wake up in the morning thinking “I’m gonna die if I get a flu”