I'll try my best to make this as straightforward as possible.

In each cell in your body, Oxygen comes in in the form of 2 oxygen's doubly bonded, the 2 oxygen atoms are split apart, and combined with a carbon atom bonded to hydrogens. This results in a free hydrogen, which is pushed through some protein machinery to force a phosphate group onto adinosine diphosphate, creating adisonine triphosphate, otherwise known at ATP. ATP is the source of energy in the body, used for everything from moving your muscles to digesting food. The resulting CO2 molecule is expelled through your lungs.

This is why we breathe in oxygen, eat carbon based foods, and breathe out CO2. It's all about creating ATP, which is the source of energy for all biological processes.

Edit: other organisms make ATP differently, using light or non-carbon based processes. This is just what humans and other animals do.

Source: Took organic chemistry and biochemistry in college and I at least remember this intersting chemical process.

Milk does not suddenly go bad on the expiration date. It could even be fine a week or two later if stored in the fridge.

Expiration dates are very conservative estimates of when the item will go bad.

For example, the method of preserving normal fresh milk - pasteurization - is to heat it to a certain temperature for half an hour.

Pasteurization will kill all or almost all the bacteria in the milk. Even if a tiny amount survives, if the milk is kept cold, it would not be able to reproduce enough to spoil the milk by the expiry date. If they get really lucky with the pasteurization, they may even kill everything and your milk will be OK 2 weeks AFTER expiry. But the manufacturers cover their asses and give you the shortest time, just in case.

There are situations that would seem to make that happen. Evolving underwater, for example. Without fire, it's really hard to imagine a species developing beyond the basic tool use we see in dolphins. Fortunately, it's not likely a species would develop much more than dolphin-level intelligence without fire, either. Brains, especially the complex, wrinkly brains we humans have, are really expensive to build and maintain. That's why so many species invest in claws and teeth instead. Dentin and keratin are pretty cheap. But if you use your brain to figure out how to get more nutrients (especially fats and proteins) from your food by cooking it, then evolution selects for that brain. That's part of how our brains evolved. It's hard to see how a species could leverage high brainpower to increase nutrition from food to that point without fire. Maybe they could do it by fermenting meat, but that would require other advancements that I just don't think are likely.

> Imagine holding a ball at arm's length

This is a little misleading, because a tennis ball at arm's length would be a closer analogy to the view from geosynchronous orbit. A tennis ball has a diameter of about 2.5 inches, and the average human arm is ~25, so you're viewing from ~5 radii away. The Earth's radius is ~4,000 miles, so you'd be viewing from ~20,000 miles away (geosync orbit is 22k).

The view from the ISS is more like holding a ball (250 miles / 4000 miles) * 2.5 inches = 0.16 inches sorry, twice that, 0.32 (since one of those is a radius and one is a diameter) from your eye, at which point it would be brushing against your eyelashes.

But it turns out the rotation's still pretty slow even that close up.

It actually usually restarts on it's own. Sometimes a mild electric shock is used to restore normal rhythm, or the surgeon may massage the heart to get it going.

Defibrillation uses an electric shock to convert abnormal heart rhythms, called fibrillations, into a normal heartbeat (called a sinus rhythm). Defibrillation causes much of the heart muscle to depolarize (a change in electric charge within a cell). This depolarization causes the sinoatrial node (your heart's natural pacemaker) to reestablish sinus (normal) rhythm.

With cardiopulmonary bypass, you're actually weaned off the machine. Your body is re-warmed (they cool you down, which actually reduces risks of brain damage and other issues that arise from being put on the bypass), and your arterial blood gas will be measured. Arterial blood gas is a measurment of how much oxygen is in your bloodstream. It is measured via a blood sample from the arteries. Then, the anesthesiologist turns back on silenced alarms (they don't want to hear the flatline (no heartbeat) alarm throughout the surgery, so the monitor is put on "silence"), adjusts monitor and ventilator settings, and adjust oxygen flow rate, as necessary.

After the aorta is de-clamped, the heart usually starts to beat without help, but sometimes drugs (called inotropes- they are drugs that "tell" your heart muscles to contract; some inotropic drugs "tell" heart muscles to contract with more force; other inotropes "tell" heart muscles to contract less forcefully) are needed.

Cardiac (the medical term for anything to do with the heart) massage may also be needed to get the heart restarted. The medical personnel will use their hand and directly massage the heart itself. It's basically direct compressions, like in CPR, but instead of using the force from your arms and hands over the sternum (breastbone) to "massage" the heart back to beating, it's directly to the heart muscle itself.

It does sometimes beat irregularly at first, and an electric shock directly applied to the heart muscle may be needed to restore sinus rhythm, much like in automatic external defibrillation. Sometimes, the heart will fail to maintain a normal rhythm, and an internal pacemaker (a device that shocks the heart into sinus rhythm) may be implanted.

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The funny thing is humans are actually terrible batteries. They should have come up with a better excuse for us in The Matrix (like parallel processing or something).

What the he will what?

Dang it, now I want to walk around with a lightbulb that is powered by me all day...

Damn you just answer everything lol. Thank you.

As someone who uses contemporary Penn weekly, thinking about the old structure makes me so sad. Penn Station is a dismal, depressing place. Even the improvements over by the LIRR suck. They set up a whole room of diffuse lights to simulate daylight, which sounds great... Walking through at 10:00pm at night and suddenly being in "daylight" is nauseating.

Considering we have driven the lizard people underground I'd say us warm blooded mammals are doing pretty good!

Earth rotates fast in the sense that the linear speed of the rotation at the equator is fast. It does not rotate fast in the sense that it makes a full spin quickly (it doesn't; it makes a full spin in - from a distant perspective - 23 hours and 56 minutes).

If you were floating just above the equator and not co-rotating with the Earth, you would see the land below you flying by at an extremely fast pace (about 1.5x the speed of sound). But if you're in space, you're quite far from the surface of the Earth - at least a hundred miles or so - so that speed doesn't look too too fast.

In the very best case, where you're 100 miles above the Earth, not in orbit, and not co-rotating at all, you'd see the Earth move at a speed of about 0.2 degrees across your field of view per second. That isn't nothing, and you probably would notice it if you were paying attention, but it's easily lost in other motion. For comparison's sake, a finger at arm's length covers about 1 degree, so an object directly below you would take about 5 seconds to cross the width of your finger at arm's length. Or, put another way, it would move across your field of view at about the same rate as a person walking slowly on the other side of a football field from you.

Fundamentally, it looks slow because of parallax: faraway objects don't move across your field of view very quickly even when they're moving very fast.

In practice, though, you never get even that much, because:

• If you're in orbit anywhere near the Earth, you're actually moving faster than the Earth rotates (by a lot!), so you mostly see your movement over its surface. You're also higher than the 100 miles in our example: both active space stations (the ISS and China's Tiangong) orbit at about 250 miles up.
• If you're not in orbit, you probably just launched from the surface of the Earth, and you still have the horizontal momentum you started with, so you're still more-or-less co-rotating with the Earth.

I, for one, like Kent Brockman, welcome our new lizard overlords.

It takes 24 hours for the earth to make one rotation on its axis- it's roughly 1000MPH. If you were to sit in the exact same spot in space for say, 6 hours, you would be able to observe the Earth make a quarter rotation - about 6250 miles.

For contrast, NY to Hawaii is about 5000 miles. Beijing in Eastern China to Istanbul in Western Turkey is about 7000 miles. You would be able to notice the change, but six hours is a long time to observe for, so you may not really perceive it.

Yep, this is the answer, pretty much. I think all misconceptions with Earth and space are directly linked to misconceptions of scale and size ratio.

I just read up on that actually, the pain has started to slow down but when it first started it felt like a million knives stabbing the side of my head. I appreciate the help. Thank you.

OP would love night sky timelapse videos or long exposure photos, really shows how quickly things do move even tho its barely noticeable from where we are

The part about humans making heat I already knew from the Matrix thanks

If you were experiencing a migraine, you would probably be too sensitive to light to post anything from a screen. It isn’t always the case, but light sensitivity is a very common symptom. You might also see “auras” around objects. The pain is generally much worse than a regular headache too.

The science of building engines has advanced significantly. Engines are mass produced at nigh higher tolerances these day. If an engineer wants a hole with a diameter of 4 inches today you get a hole with a diameter of 4 inches +/- a few thousandths of an inch. This means pistons of the cheapest mass produced engines today seal up much tighter than those built 40 years ago leading to less exhaust gasses escaping the combustion chamber that reduces efficiency. These tighter tolerances also allow you to run lower viscosity oil which is easier to pump.

Cars are now all fuel injected instead of carburated which means a computer can precisely deliver the exact amount of fuel into an engine, measure how much excess fuel is in the exhaust, how much air is going through the intake and make adjustments depending on throttle position and engine load. Engines also can make adjustments to advance or retard timing of the spark do adjust and when the intake and exhaust valves open in relation to each other. While at low RPMs the air flows slowly through your engine which doesn't promote swirling of the air fuel mixture leading to a less efficient burn. Modern engines can open the intake valve later or open them less to speed up the movement of the air then at higher RPMs it will gradually open the intake valve more and earlier when the air flowing through it is moving faster. The same principle applies to the exhaust side to harness the inertia of the exhaust gasses flowing through your pipes in order to clear out more air from the cylinders through a process called scavenging. At high RPMs you can leave the exhaust valve open during part of the the intake stroke and open the intake valve earlier. This means both valves are open at the same time which allows the inertia of the exhaust gasses to help draw in fresh air through the intake valve into the cylinder allowing the cylinders to have more air and fuel in it. Early muscle cars operated in this mode all the time leading to the distinctive burbling sound at idle which was basically the engine having trouble getting enough air to keep running make it inefficient at low RPMs. Modern cars can adjust valve timing so they operate efficiently at all engine speeds.

No, for several reasons:

1. The "expiration date" is not some hard-and-fast switch that gets thrown where what once was perfectly safe will now make you ill. Spoilage just doesn't work like that. For liability reasons the manufacturer almost certainly sets the date very conservatively, and if anything the date reflects the quality of the food rather than its safety (which is why the date is usually listed as "best before"). Stored properly, milk is likely to be safe to drink several days past its "expiration date," more if it is unopened. It will also start to taste and smell bad before it becomes really unsafe.

2. If you drink a gallon of milk, regardless of the expiration date, you will be sick; ask anyone who's been on the internet long enough to remember the "milk gallon challenge."

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Imagine holding a ball at arm's length and rotating it so slowly it would take 24 hours to rotate it. That's really slow, right? That's what the photo from space looks like.

It only sounds fast when we hear it in everyday units like miles per hour because the earth is really big.

McNamara terminal at Detroit.