>Fields, as in scientific fields? Are there any that still commonly use imperial units at all?

More industrial fields, but it's still pretty common in engineering R&D in fields where the academic, scientific, and industrial lines get blurred.

Automotive and Aerospace engineering, for example.

>Are there any that still commonly use imperial units at all?

Aerospace is still overwhelmingly Imperial, at least until you get to space. Altitudes are measured in feet, speed in knots, thrust and payload in pounds, power in horsepower (particularly for piston-cylinder engined aircraft).

What you're describing isn't "the metric system," and is commonly done in Imperial/American standard units in some fields (e.g. kPSI or MPSI for large units of pressure). Prefixes in units aren't monopolized by SI.

Liter isn't an SI unit simply because it's not the base unit of volume. Volume is inherently just built on distance measurements, and the SI system already has the meter, ergo the base unit of volume is the cubic meter.

"Lack of coherence" means it isn't derived explicitly from a core SI unit. The fact that it can be expressed in SI units without rounding doesn't matter.

This also ties to a huge misunderstanding that people have about the metric system. The strength of SI isn't remotely related to the prefix units (i.e. the "moving the decimal point over"). Instead, the core power of the metric system is that more complicated units are all derived directly from other units; so, 1 Pascal is explicitly 1 Newton spread over 1 square meter. 1 Newton is explicitly 1 kg accelerating at a rate of 1 meter per second per second. Building on those basic units is what makes the SI system as powerful as it is, as it means you don't have weird constants that you have to factor into all of your calculations (e.g. the wonderful world of pounds-force vs. pounds-mass).

So, all air-breathing heat engines (from internal combustion engines in your car to supersonic aircraft engines) require the air to be compressed above atmospheric conditions before you add fuel and combust it. The more you can compress the air before igniting it, the easier it is to extract the energy from the reaction and use it for work or thrust.

For engines designed for really really high speeds this gets tricky as the physics behind how air flows get really wonky when you get up to the speed of sound or faster, which can make it really really difficult to compress the air (and, more importantly, make it really difficult to make a single kind of engine that can compress both subsonic and supersonic airflows).

Turbojets are just turbine engines, where the airflow is run through a series of compressor blades on the inlet of the engine. These are outwardly similar to the engines on most jet aircraft, although modern engines are turbofans, which bypass a significant portion of the air around the compressor for efficiency reasons (instead of in a turbojet where everything goes into the compressor).

Ramjets have no compressor blades, and instead are ducted in a special way to use the aircraft's forward momentum to compress the air as it enters the engine ducts. Scramjets are the same concept, but are used for even higher speed airflows (ramjets compress air to subsonic velocities inside the engine before combustion, scramjets allow it to remain supersonic). However, this poses a problem at low speeds, because without the forward motion of the aircraft, the ramjets don't work.

Because people don't want them banned, and because the negative effects are, for most of the population, controllable.

>Why haven’t they been banned for the sake of the population?

The effects of alcohol and tobacco on the overall population basically amounts to a rounding error.

>but would I be incorrect saying Catholicism was the first Christ based religion?

Absolutely.

The first Christians faiths were the original cults that sprang up in the wake of Christ's death circa 30ish AD.

Those cults then spread across the Eastern Mediterranean and started forming their own religions, and were only broadly unified into a single church a few hundred years later by the Council of Nicaea in 325 AD, which is broadly considered the origin of the original Christian "Church" as accepted by Roman Catholicism, the various Orthodox Churches, the Assyrian Church, and the Anglicans, and (as a result) by Protestantism further down the line.

The Catholic Church as it exists today was only really formed 700 years later, when the Greek Orthodox and Roman Catholic churches split from each other in the Great Schism. But even prior to the Schism there were tons of variant churches all following the Nicene Creed; the only reason the pre-schism Catholic Church was so large was because of it's relationship with the Roman Empire.

Honestly; if you're looking for the faiths closest to OG Christianity, that would be either the Coptic, Oriental Orthodox, or Assyrian Churches.

Judaism, Christianity, and Islam are all directly related. Judaism is the oldest by a few thousand years, and arose in the Middle East with some influences from Zoroastrianism. The important part is that the Jews believe in the idea of a Messiah, who will come to Earth at some point and uplift humanity.

Christianity is an offshoot of Judaism that arose in the first few centuries of the common era. Christianity is based around the idea that Jesus Christ, a Jewish religious figure from the Second Temple era, fulfilled the idea of the Jewish Messiah, and was the son of god.

Islam rose a few hundred years after Christianity in Arabia, and centered on the conquest of Arabia by Muhammad. Within Islam, Muhammad is considered the final prophet, overriding the scriptural rules of both Judaism and Christianity.

Buddhism is a completely separate religion that arose in India, and is slightly older than Christianity, centered on the teachings and philosophies of Siddhartha Gautama, who was enlightened and thus became the Buddha.

>I've no idea where you got this idea from. The zeroth law is not tautological, can't be derived from the other laws, and (like the third law) is often ignored in pedagogical contexts because of its relative subtletly and obscurity.

The zeroth law is absolutely tautological; it's not remotely needed because the phenomena described by the zeroth law are necessary consequences of the second law.

>Well, the entropy of what? If I put a glass of room-temperature water in the fridge, its entropy will certainly decrease.

I mean, I'm simplifying for the purposes of ELI5.

The correct description only applies to closed systems.

Enthalpy is actually closer to energy, and basically amounts to a slightly different methodology for bookkeeping of the total energy contained within a system. The only difference between enthalpy and energy is that enthalpy takes what we call "flow work" into account, or the additional energy extractable/storable in a medium via the combination of pressure and changes in volume.

Enthalpy ends up being used in place of energy in a lot of situations where pressure-driven flow is important (e.g. turbines).

Entropy is a separate thermodynamic quality that more or less describes the "desire" of concentrated energy/enthalpy to disperse.

Thermodynamics is the study of the motion and usage of energy, and is a critical aspect of all sorts of other scientific fields like chemistry and fluid dynamics.

Thermodynamics functions on three core laws. The first law simply states that energy must be conserved, and cannot be created or destroyed. The second law states that entropy cannot decrease, or (put more simply) that energy seeks to expand and flow from areas of high energy to areas of low energy. The third law basically just shows that entropy cannot remain constant. Thus, the second and third laws are typically bundled together to state that entropy can only increase over time.

There's also a tautological "zeroth" law, which isn't an actual law, but which is used as a teaching tool so as to sidestep some later issues in dealing with the relationships between entropy and energy. The zeroth law just states that heat always flows from hot to cold, which is true, but which is a consequence of the three laws of thermodynamics working together.

>The EU can make arbitrary changes very quickly if all member states are in agreement

And the US can make arbitrary changes very quickly if only 50% of the house and 60% of the senate is in agreement. That's a hell of a lot easier to do than the insane unanimity required for EU legislation.

>You could point to the sudden changes in economic and military policies in the EU following the invasion of Ukraine as an example of the EU reacting quickly to something.

It was still far too slow to matter.

>For example, it doesn't have a military or police force to speak of, and it has little involvement in public services and social policies.

And the only reason this isn't an immense problem is entirely because the US props up the EU from a defense perspective.

>Oh, so it’s like the US in short.

Again, not exactly. It has a lot of systems that are very similar to the US, but their central government is exceptionally weak and unable to actually function that well in a crisis, which is a huge difference in terms of why the US is more powerful than the EU despite the EU having a larger population and a larger economy.

They don't exactly "resolve" conflicts, they just attempt it. It doesn't always work, and even when it does it's glacially slow.

By comparison, in the US our government actually has two speeds; glacially slow, and lightning fast. Generally, Congress does nothing, but in genuine emergency situations consensus emerges pretty quickly and Congress can pass legislation in the blink of an eye. The EU has no such ability, because it's own bureaucracy and laws stand in the way of the EU central government by design.

>I also think that all their med schools are intertwined and it’s easier to get a job in other EU countries.

That's not exactly groundbreaking, though. The US has had similar systems for professional degrees in place for decades, whereby individuals in one state can have their credentials honored in other states.

The only difference is that the individual EU "nations" continue to pretend that they're independent from one another. Hence, the nations of the EU continue to call themselves separate countries, whereas that isn't done in the US.

In this case, it's the overarching EU that's weak, entirely because too much power is maintained by the nations of the EU.

It gets a little confusing because the EU isn't formally a confederated nation, they just functionally act in that manner.

The EU is effectively a confederation, organized similarly to how the US was under the Articles of Confederation prior to the current Constitution, as well as to the CSA during the American Civil War.

Confederations are, outwardly, very similar to Federated nations (e.g. the US, Russia), but have significantly weaker central governments, and a lot more legislative and executive authority is given over to the component states. The pro of this is that your local governments have quite a bit of leeway with respect to how they function, but the con is that if there are problems that are too big for your local government to solve, they have to be solved at the level of the central government...which is a huge issue, because of how weak that central government is. This means that confederations are pretty weak in crisis situations, which of course is absolutely not what you want from a central government.

Again; the US tried this system of government, and it failed pretty catastrophically.

About that...

Texas is no longer an exception. The SCOTUS resolved this in the wake of the Civil War.

Hawaii also isn't an exception, but culturally is probably the most distinct from the rest of the US (alongside Alaska).

>is it because wales and scotland self-indentify as countries and we want to respect their right to do so ?

Basically.

>what is it that makes something like wales or scotland a country, even though they are part of a larger country the UK, that would not also make something like a US State a country?

Because we kind of had this whole thing about 160 years ago where we decided no state within the US would call itself a country.

The Sun isn't "burning" in a conventional sense, but instead is going through nuclear fusion. It's a completely different process.

I mean, the idea is predicated on you standing precisely on the North Pole.

In such a scenario, all directions are, by definition, away from the North Pole, ergo they're all South.

The eye doesn't "process" in FPS. Instead, once a series of images reaches about 60 FPS, your brain stops interpreting them as individual images and instead interprets them as a continual "video. Above that, you can absolutely tell the difference in standardized framerates, but it's not as big as the difference in interpretation that happens at around 60 FPS.

This is entirely too big of a topic (pun maybe intended) to cover in a single ELI5, so unless you give us an idea of what your hangup with infinity is, this isn't going anywhere.

The effect is identical, but the economics of EVs are such that they barely make sense at the moment, such that it's much more important for them to stretch every single potential advantage in range they can get. One of those is reducing aerodynamic drag.