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You've put into scientific terms what I can't cause it's been too long since I've done any physics. In layman terms, the molecules in hot water are bouncing ar

You've put into scientific terms what I can't cause it's been too long since I've done any physics. In layman terms, the molecules in hot water are bouncing around more and thus easier to form crystal structures because of the higher-energy state. Molecules at room temperature have to be forced into crystal structures which takes longer.

baddox 6y ago
A little more explanation is required, since the boiling pot still needs to pass through room temperature on its way to freezing, and it’s not clear how at that point it has a head start on the other room temperature pot.
- jhrmnn 6y ago
  Especially since there is no such thing as water memory.
  - iso947 6y ago
    I wonder how many kids watching frozen 2 will subconsciously accept “water has memory” as a fact and believe it in 20 years time, being unable to source why they think it, just something “they know”
    - thaumasiotes 6y ago
      That's something people have believed basically forever. The most modern example would be homeopathy, which is explicitly based on the idea that water has memory and significantly predates Frozen 2. So, the answer to your question is "a really large number", but it's not obvious that Frozen 2 would have influenced them.
      - stan_rogers 6y ago
        It would be more correct to say that homeopathy became explicitly based on water memory after atomic theory and the size of atoms achieved mainstream acceptance. And while Dalton and Avogadro had certainly made convincing arguments based on chemistry in the early 19th century, and thermodynamicists like Boltzman had models of heat and heat transfer that seemed to depend on particles, it wasn't until after Einstein's paper on Brownian motion and Rutherford's interpretation of the Geiger-Marsden experiment that homeopathic dilution just being dilution became an unsustainable notion. It was always a silly notion, especially when numbers like 30C - a dilution of one part in 10^60, or one molecule of the target substance in 3 × 10^34kg of water, after you understand what molecules are - were being thrown around, but there was at least a plausible explanation before, say, WW1.
  - cartoonfoxes 6y ago
    I think this is one of those "technically false, but there's a story behind it which makes sense" situations. For much of our history as a species, water most certainly did have "memory" if you consider our pre-modern experience with disease-causing pathogens.
- matt-attack 6y ago
  This is precisely what I’ve always wondered. Can it have momentum?
  - VLM 6y ago
    Convection currents absolutely do have momentum. If you want a very simple analogy, boiling water is strongly self stirring especially in a cold environment, whereas cold water in a cold environment does not self stir. This effect is very old popular science filler material, and in the 80s there was possibly a Mr Wizard or similar TV episode where the effect was demonstrated by taking aquarium air tubing and an "empty" mustard squeeze bottle (only worked with one specific brand, plochman's mustard I think) and fill the "empty" mustard bottle such that you've made free yellow food coloring, then stick the aquarium hose in the clear bucket of freezing water and squirt in some mustard food coloring and watch how the convection currents in the previously hot container are huge and the water turns uniformly yellow in seconds whereas the previously cold water the yellow diluted mustard-water just sits there, pretty much. Its easy to use the hose and a stopwatch to try and quantify the currents. Now a days kids would probably use a smartphone camera or ipad and then use a video editing program to quantify the actual water current speeds vs time/location, but its easy to miss the important overall qualitative interpretation by trying too hard to generate too much quantitative information.
- Tuna-Fish 6y ago
  The boiling pot will never pass through the state where it's uniformly room temperature. We did this in high school, and put 3 thermometers in both buckets. At the point when the water at the very bottom of the hot bucket reached ~6°C, the top of that bucket was still >60°C. This was in a 30cm tall 10 liter bucket, it really surprised us how strongly the water stratified. The top loses heat fast through evaporation, but the temperature of the water at the top does not fall very fast because the newly-cold water flows rapidly down the sides of the bucket. If you add constant mixing to both buckets, the hot one freezes slower than the room-temperature bucket.
yread 6y ago
It's not just individual molecules, the vortices that form in boiling water keep going even after it reached room temperature and help distribute the heat so that it can be taken away
- usrusr 6y ago
  In other words inertia. And while that surely winds down eventually, the same convective effect that created the movement during heating will continue while chilling, sustaining it longer than one would expect. In a typical pot, heat is added at the bottom and lost at the top (mostly through evaporation) and a bit at the sides. When heat isn't added anymore energy loss will still be mainly at the top and at the side, at least when not put on a cold surface. When suspended, e.g. on a gas stove, air convection will mage sir that the sides lose now energy than the bottom. So the direction of the convective drive remains the same in the switch from (usually more violent) heating to chilling, so it will sustain relatively well. On the other hand, while the inertia fades the energy contained in the movement is turned into additional heat that needs to be transported say, but that's a miniscule amount of energy compared to that contained as heat: try to heat up water beyond room temperature by stirring!
  - ricksunny 6y ago
    Ah, the model you articulate here suggests that the convective currents prevalent in an (initially) hotter pot of water as it cools, is what drives the higher rate of heat energy loss as compared with a pot of water initially at a uniform temperature matching ambient. As convection does indeed exchange heat faster than conduction, then so long as the differential temperature between top and bottom continues as the pot cools, (and yes the fluid flow does trivially have fluid momentum i.e. inertia mentioned above), then there is a case that it can continhe to lose heat energy faster than the relatively still flowing, initially room temperature, pot of water.

baddox 6y ago

A little more explanation is required, since the boiling pot still needs to pass through room temperature on its way to freezing, and it’s not clear how at that point it has a head start on the other room temperature pot.

jhrmnn 6y ago
Especially since there is no such thing as water memory.
- iso947 6y ago
  I wonder how many kids watching frozen 2 will subconsciously accept “water has memory” as a fact and believe it in 20 years time, being unable to source why they think it, just something “they know”
  - thaumasiotes 6y ago
    That's something people have believed basically forever. The most modern example would be homeopathy, which is explicitly based on the idea that water has memory and significantly predates Frozen 2. So, the answer to your question is "a really large number", but it's not obvious that Frozen 2 would have influenced them.
    - stan_rogers 6y ago
      It would be more correct to say that homeopathy became explicitly based on water memory after atomic theory and the size of atoms achieved mainstream acceptance. And while Dalton and Avogadro had certainly made convincing arguments based on chemistry in the early 19th century, and thermodynamicists like Boltzman had models of heat and heat transfer that seemed to depend on particles, it wasn't until after Einstein's paper on Brownian motion and Rutherford's interpretation of the Geiger-Marsden experiment that homeopathic dilution just being dilution became an unsustainable notion. It was always a silly notion, especially when numbers like 30C - a dilution of one part in 10^60, or one molecule of the target substance in 3 × 10^34kg of water, after you understand what molecules are - were being thrown around, but there was at least a plausible explanation before, say, WW1.
- cartoonfoxes 6y ago
  I think this is one of those "technically false, but there's a story behind it which makes sense" situations. For much of our history as a species, water most certainly did have "memory" if you consider our pre-modern experience with disease-causing pathogens.
matt-attack 6y ago
This is precisely what I’ve always wondered. Can it have momentum?
- VLM 6y ago
  Convection currents absolutely do have momentum. If you want a very simple analogy, boiling water is strongly self stirring especially in a cold environment, whereas cold water in a cold environment does not self stir. This effect is very old popular science filler material, and in the 80s there was possibly a Mr Wizard or similar TV episode where the effect was demonstrated by taking aquarium air tubing and an "empty" mustard squeeze bottle (only worked with one specific brand, plochman's mustard I think) and fill the "empty" mustard bottle such that you've made free yellow food coloring, then stick the aquarium hose in the clear bucket of freezing water and squirt in some mustard food coloring and watch how the convection currents in the previously hot container are huge and the water turns uniformly yellow in seconds whereas the previously cold water the yellow diluted mustard-water just sits there, pretty much. Its easy to use the hose and a stopwatch to try and quantify the currents. Now a days kids would probably use a smartphone camera or ipad and then use a video editing program to quantify the actual water current speeds vs time/location, but its easy to miss the important overall qualitative interpretation by trying too hard to generate too much quantitative information.
Tuna-Fish 6y ago
The boiling pot will never pass through the state where it's uniformly room temperature. We did this in high school, and put 3 thermometers in both buckets. At the point when the water at the very bottom of the hot bucket reached ~6°C, the top of that bucket was still >60°C. This was in a 30cm tall 10 liter bucket, it really surprised us how strongly the water stratified. The top loses heat fast through evaporation, but the temperature of the water at the top does not fall very fast because the newly-cold water flows rapidly down the sides of the bucket. If you add constant mixing to both buckets, the hot one freezes slower than the room-temperature bucket.

yread 6y ago

It's not just individual molecules, the vortices that form in boiling water keep going even after it reached room temperature and help distribute the heat so that it can be taken away

usrusr 6y ago
In other words inertia. And while that surely winds down eventually, the same convective effect that created the movement during heating will continue while chilling, sustaining it longer than one would expect. In a typical pot, heat is added at the bottom and lost at the top (mostly through evaporation) and a bit at the sides. When heat isn't added anymore energy loss will still be mainly at the top and at the side, at least when not put on a cold surface. When suspended, e.g. on a gas stove, air convection will mage sir that the sides lose now energy than the bottom. So the direction of the convective drive remains the same in the switch from (usually more violent) heating to chilling, so it will sustain relatively well. On the other hand, while the inertia fades the energy contained in the movement is turned into additional heat that needs to be transported say, but that's a miniscule amount of energy compared to that contained as heat: try to heat up water beyond room temperature by stirring!
- ricksunny 6y ago
  Ah, the model you articulate here suggests that the convective currents prevalent in an (initially) hotter pot of water as it cools, is what drives the higher rate of heat energy loss as compared with a pot of water initially at a uniform temperature matching ambient. As convection does indeed exchange heat faster than conduction, then so long as the differential temperature between top and bottom continues as the pot cools, (and yes the fluid flow does trivially have fluid momentum i.e. inertia mentioned above), then there is a case that it can continhe to lose heat energy faster than the relatively still flowing, initially room temperature, pot of water.