However outdoors temperature is usually lower than 25C well it is in Cambridge at this time of year anyway If we use these two yardsticks then we can say that 40 is twice as hot as 35 or that is twice as cold as 0. Well that's what I think anyway Take a given volume of water say V and time how long it takes today to freeze say T. Tomorrow it will be so cold that, twice the volume V will freeze in the same time T. Any volunteer? How about when we're talking about 0 Fahrenheit or 0 Rankine?
Therefore I would approach the problem as follows. IMO, twice is cold means half the heat,therefore half the temperature above absolute 0. Hence in terms of Centigrade, it would be or thereabouts, Fahrenheit would be something, and Kelvin Take that to be 70 deg. Twice as cold would be twice as far from comfort, or deg F.
That's how I'd define it, at least for a first crack at it. A more refined definition of what it would mean might account for rate of heat loss from one's body - but at which temperature does one put on a coat and make the problem terribly nonlinear? I assume the poster of this Q. Well, my twopence worth is this: Zero degrees centigrade is 32 degrees Fahrenheit. Therefore 16 degrees Fahrenheit is twice as cold. Convert it back to Centigrade and the answer is But then, twopence doesn't go very far these days.
So does this mean that 'twice as cold' and 'half as hot' are synonymous? And where do the Brass Monkeys come in? I'm confused! The answer is a bit more complicated in Fahrenheit as 0 degrees is approx Twice As Cold as Zero.
Doug Chinnock. Reply to author. Report message as abuse. Show original message. Either email addresses are anonymous for this group or you need the view member email addresses permission to view the original message. Physics hasn't been able to cool anything quite this cold. Twice this cold is still 0 K.
Edward Best. It all started with a quote at the end of my auto-signature: "Today it is zero degrees, tomorrow it will be twice as cold. The answer HAS to be zero. When you say: "Today it's twenty degrees, tomorrow it will be twice as hot", you know that tomorrow will be 40 degrees--because you use zero as a baseline. You can double zero, but it's still zero. Tony Ventura.
The error in your logic is the assumption that 0 degrees represents no temperature at all, which is of course incorrect. Twice as cold would be the same thing as half as warm. If we were dealing with the Celsius scale, 0 degrees is equal to degrees Kelvin. Half as warm would be However, if we were talking about what temperature would feel twice as cold to a living organism, then there are different mechanics at work.
The feeling of cold is due to the heat escaping from the skin into the ambient surroundings. In this case twice as cold would occur at that temperature at which the escaping heat is at twice the rate as what occurs at the reference temperature, in this case 0 degrees.
I think I'll leave that piece of research up to you. Travis Murray. True, but what if you say "Today is 20 degrees, tomorrow will be twice as cold"? What do you use as your baseline?
Back in , however, Jacques Charles was able to prove that, for any given increase in temperature, T, all gases undergo an equivalent increase in volume, V. Rather handily, this allows us to predict gaseous behaviour without reference to the particular gas being examined. The Platonic ideal falls apart at very high pressures because of simple physical and chemical interactions. For the sort of pressures needed to use a gas as a thermometric medium ie measurer of temperature on earth, however, all gases exhibit the same, very simple behaviour described by the following equation:.
Which means if you keep the pressure constant, as the temperature changes so does the volume. One very nifty thing about this is the way it makes it possible to create a temperature scale which is independent of the medium used to delineate the scale. Back in , P Chappuis conducted studies using gas thermometers which used hydrogen, nitrogen, and carbon dioxide as the thermometric media at the International Bureau of Weights and Measures BIPM.
Regardless of the gas he used, he found very little difference in the temperature scale generated. If the temperature of the gases changed by a value T, and the pressure, P, was held still, the increase in volume, V, was the same regardless of the gas being used to set the scale. One of the most important consequences of this discovery is the recognition that there is a naturally defined absolute zero temperature value.
When the pressure exerted by a gas reaches zero, the temperature is also zero. In the International Committee of Weights and Measures adopted a scale system based on absolute temperature.
It is called the Kelvin scale and uses the same unitary value for single degrees as the modern Celsius scale. So a one-degree change as measured by the Kelvin scale represents the same change in temperature as a one-degree change as measured using the Celsius scale.
Absolute zero is, as it happens, equivalent to So 0 degrees Celsius is Using standard notation for each scale we can re-state this sentence thus:. Note there is no degree symbol used when denoting a temperature in Kelvin. Which brings us, finally, to explaining how I arrived at the temperature I listed at the beginning of this article. I know, I know, that has nothing to do with temperature. Bear with me, though, because I'll get back to temperature in a minute.
Suppose I was hired by a firm to do marketing and sales work. I was hired at the beginning of , and at the end of the year, I wanted to impress my bosses with how much I'd helped the company's bottom line. So I show my boss this chart:. It looks pretty impressive, doesn't it? My boss, if he's not paying attention, will say, "Wow! Look at how much higher the number is! You've quadrupled our sales, just in one year! But if he's paying attention carefully, he'll say, "Wait a minute! And the answer is You see, once we have a frame of reference for comparison, we realize that the difference between the number and the number isn't nearly as big as it looked in the first chart.
And I certainly didn't quadruple their sales, even though it looked like it in the first chart. The same is true with temperatures: if you want to make comparisons like "twice" or "half," you really need to have a "real" zero. Zero on the Celsius scale doesn't actually "mean" zero, because zero should mean "no heat at all" just like zero on my sales chart means "no sales at all".
We need to have a scale in which zero really means "no heat whatsoever. Fortunately, we have a scale like that. It's the Kelvin scale, in which zero is called "absolute zero" because it is the end of the line. There is no heat whatsoever at zero Kelvin.
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