The Temperature tells how warm or how cold something is, this is taught to children at school. So far so good. In the 17th century came the first thermometer, because they recognized, that the sensitivity of temperature is very subjective.
For example: If you submerge your left hand in cold water and the right hand in hot water, and after a little while then both hands in bowl of lukewarm water the left hand will find this water warmer then the right hand.
Even then you knew that fluids that were heated, expanded and by cooling contracted and so it was a question of time only until someone thought of placing certains fluids in a small cylinder, defined two fix points, to see the space between equalled, to observe the grade temperature. Thats all was arbitrary: the choice of the fluid, the placement of the lines on the cylinder and the question of how many lines.
When Homer has no money and Bart double as much as Homer, then Bart has also nothing: two times zero is zero. But that an object gets warmer, when it's temperature is doubled, even if it's 0 or -10 °F, seems logical. Twice as warm as -10 °F should be -20 °F (so colder!)??? The problem is, that zero degrees of Fahrenheit does not mean a temperature of zero. So we are looking for a temperature scale where the zero point is really the zero point of temperature.
If you would say that the temperature is double so much when the fluid measurement is double so long, you would have very different answers for 0 °F.
Besides the physicists tried to measure the temperature and then temperature itself free from every arbitrariness.
All objects are made of particles, which oscillate around their rest position. The greater the temperature of a object is, the more its particles oscillate back and forth. One says: the temperature is a measure of the particle motion or exactly the temperature is proportional to the internal energy of an object.
By temperature rising the movement of the particles of an object is greater as when it dormant. They push each other out of the way. Therefore, they need more space and because in the object is no more space, the object has just become larger.
Now we have an absolute temperature unit. If not move at all the particles, the temperature is zero. The temperature can be not less than zero, since, according to the particles move less than not at all?
Kelvin and Rankine are the absolute temperature scales, that means that 0 K and 0 R (spelling without ° !) indicate the temperature of the absolute zero point. Rankinescale and Fahrenheitscale are a couple; a difference of 10 K for instance is also a difference of 10 °C. Similarly the kelvinscale and the celsiusscale.
Now we come to the double of zero Fahrenheit calculation. 0 °F is 459,67 R, the double of this is 919,34 R, and reversed 459,67 °F. Similarly is the double of -10 °F 439,67 °F. Really very warm! So be careful the next time the weather forecast speaks of a doubling of the temperature.