Eli5: I’m trying to find the best way to word this but how does one measure “negative degrees”, like in temperature, like how do you quantify the absence of something that isn’t tangible?


Eli5: I’m trying to find the best way to word this but how does one measure “negative degrees”, like in temperature, like how do you quantify the absence of something that isn’t tangible?

In: Chemistry

Temperature isn’t actually negative. The difference between -15 degrees Fahrenheit and 85 degrees Fahrenheit would be the same difference as 0-100 if the scale was moved down. There’s no objective basis for temperature besides Kelvin, where 0 means molecules stop moving and anything below it isn’t possible.

You set an arbitrary point to be 0, basically. In celsius, this point is the freezing temperature of water. Obviously things can get colder than that, so you get negatives.

There are no “negative degrees”. There is the lowest point you can go and everything goes up from there. Metric and imperial systems just count from a set point that works for them. Absolute zero is -273C or -459F. Kelvin is a scale that starts at absolute zero as 0K and goes up in degrees C (so 273K is the same as 0 degrees C)

Negative is just after water freezes for Celsius.
It’s like looking at years and there being BC and AD.
BC being before Christ.

Also there’s one actual temperature u can use to avoid having negative.
0 kelvins is absolute 0.

You aren’t measuring the absence of something. You might be able to look at “Nothing” in temperature as 0 degrees Kelvin. The negative measurements in Celsius just means “below eater’s freezing point”. Zero Fahrenheit was originally the freezing point of a specific ice and salt mix

Well, if your question is just for temperature, there is no negative of it. We just have units that are relative at some temperature and someone decided it started from at some point. If the temperature drop from that is negative in that unit (F or C). In fact, a negative temperature in celsius may be positive in farengheit (sorry if bad spell) For that reason we have Kelvins. Kelvin is a unit of meassure that starts from the absolute 0 which is the minimun temperature posible with no heat. There is no negative kelvins.

For temperature: 0 in Celsius is where water freezes, since temperature can be colder than that, it goes into the negatives. 32 in Fahrenheit is where water freezes so the concept is the same.

Kelvin is the measurement where there is not a negative degree. When you reach 0 Kelvin (which as far as I know still has not been achieved) this is the absolute coldest anything could theoretically be

Another way of looking at it is with left and right. Pick a random point. Everything left of that is left and everything right of that is right. You can pick any given point to do that with.

Instead of left and right, temperature does the same with with zero. Pick any random temperature and call that zero. Anything colder than that is negative and everything warmer is positive. You are just counting in opposite directions.

Same thing with dates. You can look at 2000 BC for example, as -1999 AD if you like. There isn’t a year zero, so that’s why it’s off by one.

Fun fact: the opposite of heat isn’t heat but the absence of heat. “Cold” isn’t really a thing, it’s a construct for helping us compare various temperature points. Temperature is a way of measuring energy. What’s being measured isn’t an absence of something but instead a reduction on a fixed scale with an arbitrarily defined zero point.

The problem is that we need common points of reference. As early scientists developed the ability to consistently measure and quantify temperatures and built thermometers to measure those temperatures reliably and repeatedly, they had to define what we were measuring it and the steps we were measuring it in. The first common scale was the Fahrenheit temperature scale, developed by a Dutch physicist named (shockingly) Fahrenheit. Per the official paperwork, he defines the zero point of his scale as the temperature which a mixture of water and ammonium chloride freezes, which really makes little sense as a zero point until you consider the unofficial reason of zero being the lowest temperature his hometown reached while he built his thermometers and then having to backwards justify a repeatable value. He defined 32 degrees as the temperature at which pure water freezes because why not, and 96 degrees as the temperature of the human body because at this point he was still developing a foundation on which temperatures would be measured in the first place.

After a while people realized that Fahrenheit was, well, very arbitrary in the values it set so they developed another scale – Celsius. It set the zero point at the freezing temperature of water with steps of 1 resulting in 100 being the boiling point of water, which is very useful in science but odd for daily use because half of the scale is very inhospitable for human life, but it gained traction due to its scientific adaptation and has been adopted in much of the world.

There’s also the Kelvin scale, which uses the same degree increments as Celsius but defines the 0 point as the point in which there is no heat energy to measure. In Kelvin there are no negative values because nothing gets colder than 0 Kelvin, and water freezes at 273.15 degrees.

Basically, there isn’t a singular correct way to measure temperature so various decisions were made to build a consensus on how we as a society would have common scales to measure temperatures, each with its advantages and disadvantages.