Absolute zero, minus 273.15 Centigrade, is the temperature at which particle motion, and the heat that such motion represents, comes to a stop.d
Is there anything special about minus 273.15 centigrade (other than that it is the temperature at which particle motion and heat stops) or does absolute zero just happen to be minus 273.15 and could have been minus 300 centigrade or minus 150 centigrade?
I think it’s a case of a system of temperature measurement based around the freezing and boiling points of water at 1 earth atmosphere of pressure not fitting terribly well into the context of a zero-energy state, if that’s what you’re alluding to.
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This is why we have the Rankine and Kelvin temperature scales, which start with zero at absolute zero (Kelvin uses the same degree spacing as the Celsius/centigrade scale, Rankine the same as the Fahrenheit scale)
The number scheme used for temperature is ultimately arbitrary. I can come of with my own scale - with unit Ѫ - where Absolute Zero is -6189.173 °Ѫ and the triple point of water is 5826.923 °Ѫ. And then there will be simple, first-order equations to convert temperatures in Celsius, Fahrenheit, and Kelvin to my scale, and vice-versa.
It’s probably better to think of it as water freezes at 273.15 Kelvin and the Celsius system labels that point 0C
No… the melting/freezing point of water is no longer a defined point on the temperature scale.
There are two defined temperatures: absolute zero and the triple point of water. All other temperatures are measured, and with a certain degree of uncertainty. This includes the freezing point of water.
I realize that absolute zero can be stated in a number if different measuring systems that will give absolute zero different numbers.
But isn’t it true that the number in one measurement system translate to minus 273 in he centigrade In other words, if I understand, there is an absolute temperature to absolute zero, whatever it is called in whatever measuring system.
(as centigrade can be translated into fahrenhei).
My question: is this absolute point special in some way OTHER than that all particle activity and heats tops.
No.
Not a bit. It’s got that measured degree simply because that’s where the scale hit the extreme. No other reason.
Absolute zero is a defined, thermodynamic condition. On the Kelvin scale this condition is defined as 0 K. On the Celsius scale this same condition is defined as -273.15 °C. On the Fahrenheit scale this same condition is defined as -459.67 °F.
On my own, personal temperature scale (Post 4 above), I arbitrarily defined absolute zero to have a value of -6189.173 °Ѫ. Other than the fact I am the only one who uses it ;), it is objectively no better or worse than any other scale.
Perhaps you’re asking: why do we have so many temperature scales? Are the all necessary?
No.
We really only need one temperature scale. Having more than one temperature scale leads to confusion. We have more than one scale due to history. Ideally, we would get rid of the Celsius and Fahrenheit scales and everyone would use an absolute scale like the Kelvin scale. But I don’t think that’s going to happen soon…
Given that the Celsius (and Fahrenheit) scale already existed before Absolute Zero was known to be a thing, it had to have some value in those scales. If it were some other number, would you be asking about that, too?
And do you ever intend to return to your “high-level animal” thread to explain what the heck you were talking about in that one?
I believe it would be the lowest possible energy state, not that it comes to a stop. It’s still moving.
That is the “zero point energy” which is slightly above absolute zero. But yes due to the uncertainty principle there will still be some movement at the zero point energy, but because there is still movement and thus kinetic energy it is not absolute zero.
To confuse things more, while you cannot reach absolute zero you can pass through it to negative absolute temperatures, but that is more about modular math and does involve energy states and are the hottest temperatures ever; but absolute zero is about kinetic energy.
If it helps, the concept was first discovered by studying the properties of gases. If you have a sealed container of gas, held at some constant pressure, and you decrease its temperature, its volume decreases (alternately, if you hold it at constant volume and decrease the temperature, the pressure decreases, but the other way is an easier experiment to do). Now, you can’t take this all the way down to zero volume, because at some point before that happens, your gas ceases to be a gas… but you can take data before that point, and extrapolate the temperature at which the volume would go to zero (it’s a nice, easy extrapolation, because all of the data before you liquify is on a nice straight line). And if you repeat this experiment with many different gases, at many different temperatures, and so on, you’ll find that no matter how you do it, that extrapolated temperature of zero volume is always the same. Put another way, the volume of a gas is proportional to its temperature, if you measure temperature on a scale where that particular temperature is zero.
It also help to consider that “temperature” is really a measure of the kinetic energy of a confined system. You have to have more than one particle to even define temperature as you need relative movement.
Due to quantum effects, one cannot reach a point where there is zero relative movement, so you can never reach absolute zero.
Not to rehash the metric debates, but it would not be in anyone’s interest to be using a temperature scale based on nothing related to human life? Why have a scale that ranges from 260 to 303 (mostly) when describing outdoor temperature?
Well, most of the world doesn’t have a problem with -13 °C to 30 °C. So what’s wrong with 260 K to 303 K? True, each number is represented by three digits instead of two. But the advantage is that there are no negative temperatures to deal with. And of course, the biggest advantage is that we will never again have to convert between temperature scales, since there would only be one.
Is there anything different about the energy required to go up a degree from absolute zero? Is the energy the same to go from 0->1 as it is to go from 1->2 or 100->101?
You could call it “the temperature measurement formerly known as Kelvin.”
There is a fixed Boltzmann’s constant, but different substances have varying degrees of freedom and therefore different heat capacities, which can itself depend on temperature.
So the amount of energy will vary. Consider also the example of heating water from 0 to 1 degree Celsius…