Twice as Hot/Cold? What Does That Mean?

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Discussion Overview

The discussion revolves around the interpretation of the phrase "twice as hot" in relation to temperature measurements. Participants explore the implications of using different temperature scales (Celsius, Fahrenheit, Kelvin) and the conceptual challenges that arise from attempting to quantify temperature in a way that aligns with human perception.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants argue that using Celsius or Fahrenheit to express "twice as hot" is problematic due to the arbitrary nature of their zero points.
  • Others propose that Kelvin is a more appropriate scale for discussing absolute temperature, as it does not allow for negative values.
  • One participant suggests that the phrase is often not meant to be taken literally and reflects a more subjective interpretation of temperature.
  • There is a discussion about how different temperature scales can lead to different interpretations of what "twice as hot" means, with examples provided for Celsius and Fahrenheit.
  • Some participants express frustration with the ambiguity of the phrase and its implications in scientific contexts.
  • A later reply questions the meaningfulness of the expression if not using an absolute scale, highlighting the discrepancy in perceived temperature changes across different scales.

Areas of Agreement / Disagreement

Participants generally agree that the phrase "twice as hot" is ambiguous and can lead to confusion, particularly when different temperature scales are used. However, there is no consensus on a preferred scale or a definitive interpretation of the phrase.

Contextual Notes

Participants note that the discussion is limited by the subjective nature of human perception of temperature and the arbitrary definitions of temperature scales. The conversation reflects varying cultural and linguistic influences on the interpretation of temperature measurements.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics, physics, or anyone curious about the conceptual challenges of temperature measurement and human perception of heat.

Nick89
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Hi,

I was just wondering, if you say "The temperature today was twice as hot as it was yesterday", in which units are people usually referring?

Degrees Celsius doesn't make any sense, since it is perfectly possible for something to be twice as hot or cold as 0C... For the same reason I don't think degrees Fahrenheit make any sense...
So that leaves Kelvin I suppose? Twice as cold as 0 K would still mean 0 K since you can't go any lower, right?

So if today the temperature is 20 degrees C (roughly 293 K) and tomorrow it's twice as hot, would that mean it would be 293 * 2 = 586 K = 313 degrees C...? This doesn't really make sense to me either.

I suppose it's all about how humans physically interpret temperature? If we sense something to be twice as hot that doesn't mean the temperature is twice as hot in any scale we use, right?So yeah, I was just wondering, is there any 'convention' for this, or does nobody care what twice as hot means? :-p
 
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Nick89 said:
I was just wondering, if you say "The temperature today was twice as hot as it was yesterday", in which units are people usually referring?
When folks use that expression, I don't think it's intended to be taken literally. :wink:
 
Next time someone tells you "it's twice as hot as it was yesterday," ask them what they mean.
 
Here - and we are using Celsius scale only - that will mean something like "it was 10 yesterday, it is 20 today". Or "it was -5 but it is -10". Not exactly, but something like that. No idea how it works if you use Fahrenheit.
 
No reason why you couldn't do the same with Fahrenheit. It was 32 degrees yesterday; today it's 64 degrees. So--even though the units are arbitrary and the zero point is arbitrary--I guess it's OK to say the temperature has doubled! :smile:

(It would be more meaningful if you used the Kelvin scale.)
 
That it can be used same way with F is obvious, it is just beyond my experience - and cultural/language reflexes often cripple logic down :smile:
 
It's meaningless if you aren't on an absolute scale otherwise it would double from 10-20C in Canada but only go up by a third 50-68F in the USA.
 
For most people this meaniglessness doesn't matter, only some eggheads wring hands :wink:
 
only some eggheads wring hands
Thats me!
Our low temperature physics group used to have a sign over the door saying "1million times colder than room temperature" - which always slightly annoyed me as well.
 
  • #10
mgb_phys said:
It's meaningless if you aren't on an absolute scale otherwise it would double from 10-20C in Canada but only go up by a third 50-68F in the USA.

But that's exactly me point :approve:

If you wouldn't have any thermometer and someone asks you something like "how hot do you think it is", and you reply "it's nearly twice as hot as yesterday", then I can't imagine people using the celsius scale mean something completely different than people using the fahrenheit scale... While for your feeling, the temperature doubled, in reality, the temperature (depending on which units used) did not double at all...

I suppose you could look at the energy of the heat, just like you can look at the intensity of a soundwave (if the volume of sound doubles for your feeling, the soundlevel (in dB) has not nearly doubled)... Oh well, I think it's just one of those human things that don't really make sense :P
 

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