Except that water boils at different temperatures when exposed to different amounts of pressure.
So this works pretty universally on earth… Near the ground/ocean level (plus or minus a few hundred meters). Once you get outside of that specific condition the numbers move.
The nice thing about celcius and kelvin is that they’re the same scale, but celcius is just shifted 273.15 units. And it’s more intuitive for humans to work with smaller numbers with bigger relative differences. But yes, kelvin would be a lot better to work with, especially considering stuff like doubling temperature (doubling energy) would actually work correctly in kelvin.
But if there’s one thing that makes a lot of sense to base temperature enough for human use, I would indeed say it’s water, because all life uses water, we are completely surrounded by it, and it’s super important to nearly everything we do too.
Sure, but the vast majority of people live in low lying areas and even then it doesn’t shift that drastically. You need to climb a mountain to see the difference when it comes to applications of daily life.
Although now that I think about it. The same criticism applies to pretty much every definition of temperature that is based on the behaviour of matter. This also applies to Kelvin. Temperature is a property of matter and every type of matter behaves differently.
it can be just as strange to have to think in terms of adjusting for 273.15K for the misleading “freezing point of water” or 298.15K for STP, another arbitrary standard of measurement. Kelvin is no better than Rankine
This touches on something important, which is that Celsius is based on an arbitrary pressure. It’s based on an elevation that suits the region which defined it.
It is, but if you look at how Farenheit was conceived it’s absurdly nonsensical. 0°F is the freezing temperature or some mixture of chemicals, and 90°F is a guess at human body temperature lmao.
And the freezing/boiling points of water are arbitrary except in that they are used to actually define both scales. They provide easily measurable standards.
No, 0° was the lowest temperature recorded in the city Fahrenheit lived, and 100° was considered normal body temperature, with the quality of thermometer available at the time.
It’s quite arbitrary, but ends up mapping pretty nicely to comfortable ranges for humans.
Well TECHNICALLY it’s not based on the state change of water.
It’s based on the formula C = K - 273.15 where K = 1.380649×10^−23 / (6.62607015×10^−34)(9192631770) * h * Δν[Cs] / k where k is the Boltzmann constant (1.380649×10^−23 J * K^-1), h is the Planck constant, and Δν[Cs] is the hyperfine transition frequency of Caesium
Temperature isn’t a measure of entropy, but the internal energy of a system. Internal energy is the total energy sum of kinetic and thermal and gravitational energy.
You might wonder how that’s calculated, and the short answer? It isn’t. We rarely look at the actual value. This also goes for enthalpy and entropy. What matters most of the time is the difference in enthalpy/entropy/energy. If you take a look at various enthalpy numbers across textbooks and software and steam tables, you’ll see the value vary significantly depending on what they use as their 0 point. No matter where the scale starts though, the difference between two distinct points will remain the same.
I honestly am not sure what I made confusing. The definition I gave is the SI definition of Kelvin & Celsius since 2019. The formula I gave is more verbose than it has to be but it’s what you get when you expand it.
I’m not sure of the semantic difference. When I think “a meter is the distance travelled by light in X seconds” I think m = c/299792458 s, same with Kelvin.
Mixing unit definitions with formulae for things measured in those units is what’s confusing, I think. That equation doesn’t define kelvin, it defines temperature measured in kelvin.
Every scale and unit is, ultimately, arbitrary. We all do have a very good understanding of what freezing and boiling water is, though, we don’t have a good intuition of “coldest day in some random place in some random year” is. Then there’s a couple of other common points of orientation: 20C is room temperature, 37C body temperature and thus warm baths and “it’s too bloody hot outside” hover around that (you actually want wet-bulb temperature for that, but it’s still a point of orientation), another point is about 60C which is the hottest you can have a beverage and drink it without excessive slurping. Also a common temperature in cooking as that’s when a lot of stuff starts to denature, e.g. egg white is about 62-65C, the temperature you want to hit for carbonara to not get scrambled eggs.
Practically everything we deal with in everyday life (short of winter weather) is within that 0-100 range. Which is due, to, well, water being liquid in that range.
Isn’t basing a temperature scale on the freezing and boiling points of water a bit arbitrary in and of itself?
The reason they are arbitrary numbers in Fahrenheit is because they weren’t considerations when the scale was made.
Water is everywhere.
Cooking, weather, etc. You are also water.
Except that water boils at different temperatures when exposed to different amounts of pressure.
So this works pretty universally on earth… Near the ground/ocean level (plus or minus a few hundred meters). Once you get outside of that specific condition the numbers move.
So yes, fairly arbitrary.
Let’s all switch to Kelvin.
The nice thing about celcius and kelvin is that they’re the same scale, but celcius is just shifted 273.15 units. And it’s more intuitive for humans to work with smaller numbers with bigger relative differences. But yes, kelvin would be a lot better to work with, especially considering stuff like doubling temperature (doubling energy) would actually work correctly in kelvin.
But if there’s one thing that makes a lot of sense to base temperature enough for human use, I would indeed say it’s water, because all life uses water, we are completely surrounded by it, and it’s super important to nearly everything we do too.
Sure, but the vast majority of people live in low lying areas and even then it doesn’t shift that drastically. You need to climb a mountain to see the difference when it comes to applications of daily life.
Although now that I think about it. The same criticism applies to pretty much every definition of temperature that is based on the behaviour of matter. This also applies to Kelvin. Temperature is a property of matter and every type of matter behaves differently.
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This touches on something important, which is that Celsius is based on an arbitrary pressure. It’s based on an elevation that suits the region which defined it.
It is, but if you look at how Farenheit was conceived it’s absurdly nonsensical. 0°F is the freezing temperature or some mixture of chemicals, and 90°F is a guess at human body temperature lmao.
And the freezing/boiling points of water are arbitrary except in that they are used to actually define both scales. They provide easily measurable standards.
I think it’s the freezing point of brine
No, 0° was the lowest temperature recorded in the city Fahrenheit lived, and 100° was considered normal body temperature, with the quality of thermometer available at the time.
It’s quite arbitrary, but ends up mapping pretty nicely to comfortable ranges for humans.
Well TECHNICALLY it’s not based on the state change of water.
It’s based on the formula C = K - 273.15 where K = 1.380649×10^−23 / (6.62607015×10^−34)(9192631770) * h * Δν[Cs] / k where k is the Boltzmann constant (1.380649×10^−23 J * K^-1), h is the Planck constant, and Δν[Cs] is the hyperfine transition frequency of Caesium
So even MORE abstract and unrelatable
This makes no sense. K is not a constant. Is there a variable in there?
Temperature is a measure of entropy. It depends on the disorder in a system somehow.
Temperature isn’t a measure of entropy, but the internal energy of a system. Internal energy is the total energy sum of kinetic and thermal and gravitational energy.
You might wonder how that’s calculated, and the short answer? It isn’t. We rarely look at the actual value. This also goes for enthalpy and entropy. What matters most of the time is the difference in enthalpy/entropy/energy. If you take a look at various enthalpy numbers across textbooks and software and steam tables, you’ll see the value vary significantly depending on what they use as their 0 point. No matter where the scale starts though, the difference between two distinct points will remain the same.
I honestly am not sure what I made confusing. The definition I gave is the SI definition of Kelvin & Celsius since 2019. The formula I gave is more verbose than it has to be but it’s what you get when you expand it.
https://www.nist.gov/si-redefinition/definitions-si-base-units
From what I can tell, you’re using definition of the units? In that case K doesn’t equal that equation, but it is in units of that equation.
I’m not sure of the semantic difference. When I think “a meter is the distance travelled by light in X seconds” I think m = c/299792458 s, same with Kelvin.
Mixing unit definitions with formulae for things measured in those units is what’s confusing, I think. That equation doesn’t define kelvin, it defines temperature measured in kelvin.
Every scale and unit is, ultimately, arbitrary. We all do have a very good understanding of what freezing and boiling water is, though, we don’t have a good intuition of “coldest day in some random place in some random year” is. Then there’s a couple of other common points of orientation: 20C is room temperature, 37C body temperature and thus warm baths and “it’s too bloody hot outside” hover around that (you actually want wet-bulb temperature for that, but it’s still a point of orientation), another point is about 60C which is the hottest you can have a beverage and drink it without excessive slurping. Also a common temperature in cooking as that’s when a lot of stuff starts to denature, e.g. egg white is about 62-65C, the temperature you want to hit for carbonara to not get scrambled eggs.
Practically everything we deal with in everyday life (short of winter weather) is within that 0-100 range. Which is due, to, well, water being liquid in that range.
If you want to be radical, use Kelvin. At least it scaled identical to C so it’s easy to comprehend.