Half as Hot

30°C is 303 Kelvin. Half of that is 151 Kelvin, which translates into a fairly mild -122°C!
Takes out hockey stick
- New strategy to prevent global warming: just freeze all of the CO2 out of the air!
  
  I'm dreaming of a white Christmas
  
  That's one of the ways proposed for terraforming Venus. Put in a sun shield to freeze the planet, let the CO2 snow down, then process the CO2 into something that can sequester it away so it doesn't just go back into the atmosphere after removing the sun shield.
  Of course none of that is technically possible right now, but it's a lot easier on a planet that has no (known) life to destroy while working through the process.
  
  mmm, delicious carbonjack
  
  Dry snow doesn't sound like too bad of a proposition on its own.
- Aka a cool 272 Rankine for our US folks.
  
  I would be willing to bet there are more people in the US using Kelvin in their jobs than Rankine.
  Lb-mole? That one I'm not sure.
  To me, these wanna-be scientific units are weird, like, just use metric at that point 😅
  Also 1000th of an inch. Like, come on! You're just teasing us
- Wait, does it? Are joules in thermal energy per kelvin a purely linear relationship?
  
  For the most part, it varies by material and state of matter, but assuming the chemical composition doesnt change and no material changes phase, then it is pretty close to linear in most materials.
  
  Fun fact: gas pressure changes linearly with temperature. If you make one of these plots at mild conditions you can extrapolate the line down to zero pressure and measure where absolute zero temperature is
- 😱

Granted. Celsius now range from 0 to 50
Edit: ... or whatever unit you prefer. It's still the same
- Oh, it's way better than the alternative interpretation.
  
  Half Kelvins?
- wdym range from 0 to 50?
  
  0 is the freezing point of water 50 is the boiling point.
  If it's 30°c outside, it will be only be 15 after the wish, thus fit what the character said

Reminds me of a time one of my friends was happy that it was going to warm up and said something like "it's going to be twice as warm tomorrow". It was going from maybe 20F to 40F or something.
That led to an interesting discussion.

This knowledge comes in handy with marketing BS around CPU coolers. If an aftermarket cooler gets a CPU to 35C when the stock cooler is at 70C, marketing will sometimes claim it cut temperatures in half.
- I mean.... that's literally half though
  edit: I am not a science man and I am in over my head in this argument
  
  But it's not.
  Celsius and Faernheit are interval scales, not rational scales. The absolute change from one number to the next is consistent, but since you can go into the negatives, 1 is not double 2.
  Kelvin and Rankine are rational because they use an absolute zero.
  
  to make the argument even simpler, that phrase wouldn't even mean the same thing to an english person as it would to an american.
  In fahrenheit those temps would convert to 95f and 158f.
  
  If you convert those temperatures to Kelvin, they become 308K and 343K. Since Kelvin is absolute and we're measuring the same material, this tells you how much more thermal energy is there and their actual proportion to each other.
  
  308.15K is not half of 343.15K
  
  Do you also say "the temperature in the freezer has doubled" when it goes from -12°C to -24°C? Any thing else would be disingenuous.
- Usually that should mean it cuts the difference ambiant and CPU in half. Anything else would just be stupid or a lie.
- perhaps it cuts generated temperature in half, ie idle cpu is 50C, stock 70C, and aftermarket 60C
  
  That's not how it works, an "idle" CPU is already generating a not insignificant amount of heat. That why you measure the difference against ambiant air if you're at all serious about it.

I use this as an example for interval vs ratio; you can't halve Celsius because it's an interval scale where zero is arbitrary. Kelvin is ratio as it has an absolute zero-- you very much can halve it and doom near the entire planet next summer
- Doom near the entire planet
  Next Summer
  Coming to theaters near you
- arguably setting zero to absolute zero is just as arbitrary
  
  How so? Absolute zero is the coldest possible temperature, it's physically impossible for an object to be colder. Saying that's arbitrary is like saying it's arbitrary to define 0 m/s as not moving.

Careful, half of what, kelvin?
- That is indeed the joke.
- Absolute-ly

Obviously we'd all die but I wonder how exactly. This would make a good question for Randall Munroe.
- 90 F to Kelvin, halved and converted back, is approximately -190.
  It's difficult to find data on what exposure to that temperature would do, the threshold for an extreme cold warning (meaning absolutely do not go outside without heavy protection unless you want necrotic frostbite) is about 150 F warmer than that.
  
  It depends on conductive and convective transfer at that point. The atmosphere would be vastly different as that's well below the point where CO2 would snow out but you should still have enough gasses to flash freeze you.

A good genie would instantly invent a metric of "number of degrees in excess of room temperature"
- I think it's fairly well known that there are no good genies. But otherwise, true.
  
  For a present, I think it would be fun to have a contract lawyer draft up an ironclad 3 wishes contract
- Which room though?
  
  what, you never heard of the room temperature room?
- The indoor temperature is always at room temperature and vice versa. It's not constant though.

Is the temperature scale directly proportional to the heat energy? I think the amount of energy needed to raise water by 1 degree is the same no matter the starting temperature for example. Is 100°K double the heat energy of 50°K?
- Kelvin doesn’t have degrees btw you just say 50K or 100K because it’s an absolute temperature scale as opposed to an arbitrary or relative one like Fahrenheit or Celsius. I’d expect that the energy would be double though that’s more of a feeling.
  
  As long as the mixture of the substance remains constant and there are no phase changes, heat energy and temperature are linear and half the heat energy is half the temperature. In reality this only works for solids because otherwise, halving the heat energy would definitely involve phase changes.
- Well at some point you encounter a phase change, which complicates things, but mostly the heat capacity (how much energy it takes to raise the temperature) is fairly constant. In an ideal gas it is exactly constant, but that is a bit of an approximation, even if it works quite well for most gases.
- That wish just condenses the atmosphere of half of the planet for half of the time. How do you like your puddles of liquid oxygen now?

Could someone please explain?
- Let's say the summer average is 30⁰C or 303.15 Kelvin
  The absolute coldest possible temperature is -273.15⁰C, or 0K.
  Halfway between absolute zero and 30⁰C/303.15K is somewhere around -121⁰C/152K
  So if it were half as hot in the summer, it would be colder than ever recorded on earth.
  
  In short, you don't want to use a temperature scale with an arbitrary starting point for doing calculations like this. The freezing point of water is no more or less arbitrary than the freezing point of oxygen or sodium or anything else. It's just one that's somewhat useful for everyday use. When handling calculations for multiplying temperature, you want an absolute scale like Kelvin.
  Or Rankine if you're that kind of pervert.