Heat Being Repelled by Cold?

try the second law of thermodynamics

In seeking equilibrium,would the heat not "prefer" the coldest part of the rod,instead of being "repelled" by it?Could it be that the rapid cooling causes the excited molecules to slow down, and the metal to contract so rapidly that a collision occurs with the molecules behind the contact point, which expels some of the motion(heat) backwards, like waves bouncing off of a wall?There is not enough room in the suddenly cold metal for the excited molecules to move about freely,and they are squeezed out of the area like toothpaste when you squeeze the tube?(Actually, it would be a thermal wave,rather than the molecules themselves moving).I am thinking the water acts like a heat mirror on a molecular level.

Just speculation at this point.

your thinking on "suddenly cold" is quite misplaced. the hot end cools but doesn't get. cold, far from it

There's a science lesson here, somewhere. I'll find it in due time.

Titrate your study regimen by stopping when you get a headache.

Back off of the aspirin when you hear ringing in your ears.(unless your wife is yelling at you)

(That's a new chemistry word I just learned, not sure of it's correct usage here)

why don't you get a few rods made of various metals and a temperature recorder and conduct a few experiments on the outer and inner surfaces of the rods......maybe you'll sleep better at night once you've extrapolated some useful conclusions from your data and observations?..we call this science

Btu. once the water is suddenly caused to go from a liquid state to a vaporous state (steam) a huge number of btu's are required to achieve a state of change...they will be drawn from the water, the air, the rod, etc. actually 970 btu's per pound of water is required, don't forget to factor that in with your repelling molecules.

No need to condescend.

Science requires that results be repeatable by independent sources,so I challenge you to repeat the described scenario for yourself.I am certain you will get the same results.

If I could record with a thermal camera, I could take two rods,heat them to the same temperature, and immerse one in water, and leave the other in air,and watch the heat transfer in real time as it progressed up the rods.

I do not have the financial resources to obtain the required equipment to document diligently my results, but I am sure someone on CR4 has the resources on hand.

I was seeking a scientific reason for the observed results, and since no one had one, I advanced a few of my own, and as unscientific as they may be,they are as reasonable as the others I have seen here.Heat travels as a wave,does it not? And a wave can be reflected,can it not?So why could the heat not be reflected from the interface of the rod and water.Yes, I know about latent heat of evaporation,condensation, etc,but they are beside the point of the main question:Why does the heat flow away from a colder area to a warmer one?

I've grown tired of this game, good luck

Thanks for the good wishes, and thanks for your valuable input on this.

And likewise, good luck to you.

Fredski, woof!

Are you perched on that bike because you're too embarrassed to tell anyone that you've managed to get your arrogant-prick wedged between the tank and the seat?!

Friend,

Remember that heat is transferred by conduction, convection or radiation. When you say it travels like a wave, you are speaking of radiation, where heat is transferred from one object to another without any physical touch or intervening matter. In a rod, the heat is traveling by conduction--direct contact. This occurs in a bidirectional manner, so I doubt that the heat is being repelled by the cold. At the microscopic and atomic levels, it is possible that the sudden cooling is accompanied by attempts at shrinkage, which MAY decrease the conduction by a very small amount.

I agree with the suggestion earlier, to gather some samples of metal rods and instruments, then do experimental observations.

--JMM

You are correct of course, it does not get "cold" but rather much colder than before the contact with the water.The surface( in contact with the water) is cooling much faster than the interior of the rod,and progressing inward from the surface, creating a "squeeze effect" on the energy in the center of the rod,which would tend to reflect the energy from the center upward and away from the contact point.??

Just accept it.

Don't over think it, it'll give you a headache.

Some things I cannot accept,and cannot rest until I have a logical or reasonable explanation.It is in my nature to seek answers.I laid awake one night all night long,wondering where the sun came from.Finally, it dawned on me.

Here's my take.

The cold end is not as active, molecularly, so the heat can't transfer in that direction, due to less active molecules on the cold end.

This forces the heat to take the path of less resistance to the more active hot end, where the molecules are hopping and able to transmit the heat away from the lazy, cool molecules.

I'm sure there's a more scholarly explanation, having to do with atomic levels and potential energy something or other.

Maybe Tornado knows.

I don't have any explanation so far, but I wonder if some sort of illusion is involved. Too bad I don't have a thermal imager for some quickie experiments. An infrared thermometer might be a start, though, if I remember to bring mine home.

Your explains is too simplistic. There are allot of things happening. One of them, is you are creating boundary layers next to the rod. These boundary layers consists not of cool water but of steam, and with steam rises it can be heating your cooler end of the rod, making it only appear that the heat is moving....when in fact it's transferring...

It is not the steam.If you have not tried it, you simply do not understand.If the rod is held horizontal or vertical it makes no difference.Steam would rise vertically,but I can assure you it is not an illusion.Try it, you will see.

I have encountered this phenomena many times and have found it curious as well....We call it chasing the heat...if you cool from the ambient side toward the heat, it is contained....but a scientific explanation, I have none...

Well you can put me down as being on your and Hiteks side with being aware of this phenomenon as well.

I have been welding brazing and soldering since my mid teens, some 25ish years ago, and I too am familiar with this odd little thermodynamics quirk.

There is a neat little trick I learned from a old timer back in my teens about how to use this effect to drive heat into a metal shaft or bolt that is stuck in another piece of metal.

Neat thing is when done right the stuck inner part will in many instances fall right out of the piece it was stuck solid in to begin with. By driving the heat into the inner part that is stuck then cooling the outer part the outer part will set itself to the same dimensional measurement as the outside of the now hotter inner part. Once that inner part cools it contracts a bit and now that interference fit that bound it up is gone and the two pieces are free to move again.

However do it wrong and you can make the interference fit so tight that it sort of welds the two parts together rather permanently.

I had a former career as a welder and am very familiar with the phenomena you describe.

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I think heat transfer from the lower portion of the rod further up the rod is the main mechanism. (You can't really dip the piece in horizontally without immersing your hand in the water and throwing off your temperature sensation.)

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The superheated steam pocket stays attached to the metal and transfers heat up the workpiece.

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If the piece is red hot, the difference in heat between the super heated steam and the portion you are holding is extreme, and the temperature does not have to increase much before it cannot be handled without gloves.

.

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A simple test would be to heat two similar pieces and dip one in a bucket of water and stab the other horizontally into a bag of crushed ice.

That was mentioned in my earlier post....... :/..... But I was not in agreement due to a charge of not enough experience.

I am sorry but this cannot happen. I am not questioning your perception of what is happening. Only that heat does not get repelled by cold. It is possible that because one end was quenched suddenly the other end feels hotter by comparison. Heat always flows from hot to cold.

A properly instrumented experiment will clearly show this.

However physiological perception of hot and cold are mostly comparative and can give misleading signals to the brain. The situation described is related to transient conduction. The portion of the rod just away from the suddenly quenched end becomes hotter than both ends. Heat flows to both ends from this zone. That is all that happens.

" ...suddenly the other end feels hotter by comparison."

You're not holding both ends....Hold one end and heat the other, then dip the hot end in the water or a wet rag and the end you are holding will get hot instantly and you will have to drop the rod....Now do the same thing but take the wet rag and start cooling next to where you are holding and move it towards the hot end...the end you are holding remains the same temperature...

<...brought this up before...>

That would make this one a duplicate thread, then.

Is there a chance that the normal vibrations produced by the rapid cooling by water, somehow temporarily changes the metal's heat conducting property? In other words, can this paradox phenomenon be repeated without rapid water cooling (or other substanse) that vibrates long before boiling, when taking heat? S.M.

Heat should diffuse from a place where the rod is hotter to a place where it is colder. If you heat one end, the temperature varies from hot at one end, warm in the middle, and cold on the far end. If you quench the hot end, then the middle is the hottest. Heat will flow from the middle in both directions.

Heat a piece of metal on the end,for instance a long rod, until red hot. Move your hand down the rod until it is too hot to go any further.Now, immerse the hot end into cold water.The heat will rapidly travel up the rod,away from the water.
No it doesn't. What you are experiencing is the effect of heat transfer by convection from the heated water surface to your skin. As for the old tinsmith, he is affected by what doctors call the placebo effect - because he wants something to be true he convinces himself that it is true.

The experiment to convince you is simple and cheap. Take a good length of fine nichrome wire, which increases its resistance when you heat it, and wind it round the rod to be heated. Attach an ohmmeter to the ends and perform the heating and cooling.

For all of the sceptics, who write this off as an illusion, I call your bluff.TRY IT! Do not speak of which you do not know.I am very objective in my observations, and have eliminated personal bias from my results.

Perform the experiment as described, then offer an explanation instead of disparaging what you have not tried.As the Wright brothers said:"If everything that was thought to be true was true, there would be no hope for progress."

Until you have performed the experiment, your opinions are a very unscientific,uninformed, and unwarranted assumption with a basis on nothing but personal opinion.Opinions are ok, as long as they are framed as such, and not declared as irrefutable facts.

If I had the means and methods, I would record the events in real time with an infrared camera, attach a strain gauge to the rods to detect any ultrasound,record the reaction of the water from under the surface,including the liquid-vapor transition and temperature gradient around the hot rod as it enters the water.

Perhaps there is someone with curiosity out there that has the resources to explore and explain what is happening.

It is now up to the non sanctimonious scientific minds to have their turn at bat.

Er, no. You make a claim unsupported by the laws of nature. It is therefore up to you to publish your refutation, supported by a verifiable experimental process. We can help by designing an experiment, but I see no reason why the scientific community should be obliged to do anything except peer review the results.

"Chevrolet made that mistake with their Nova.They would not sell well in the Hispanic market.You,of course, know what it means in Spanish."

AAarrrrgghhh! BULL !!!

Shame on you for perpetuating such Internet-Initiated-Nonsense!!!

Doesn't ANYBODY check facts anymore, before "Forwarding" to millions of unsuspecting eyes (future readers of the thread)?!?

< ^{pik-a-link-above , any link} >

I realize you're absolutely adamant that your 'phenomenon' is, in fact, real (as attested by other observers, and your one-shot / melt-wax test).

However, you do NOT gain credibility by supporting hypotheses (such as yours) with atrociously deleterious apocryphal nonsense!

Based on info from your links, it appears I erred.However, this "rumor" was around in the early 1960's,long before the internet existed.

Insofar as George Washington and the cherry tree, however, I know it is correct,because I have the original hatchet that he used to cut down the tree.

The handle has been replaced three times, and the head wore out twice, and had to be replaced.Except for the repairs, it is all original.

You are right about the Mpemba effect being immune to decent scientific explanation. The reason for this is that the phenomena or supposed anomaly has not been described in acceptable scientific terms. . No falsifiable claims about fundamental properties are made. The 'effect' makes no specific claims about a decrease in specific heat capacity, or increase in heat transfer, or increase in freezing point of recently heated water. . The claim is too far from scientific to support a scientific response. The experiments I have reviewed, that attempt to provide a scientific response don't seem able to surmont that obstacle.

Dang! you are looking for sanctimonious and all I have available is snarky plus I am on your side as well.

BTW I am now taking claim of this effect and calling it the TCM effect before Lyn gets a hold of it and makes it a another part of Lyn------ industries something or other devices bla bla bla.

I know nothing of this but could it be as follows?

After the first heating, the outer layers are hot but there is a gradient towards a cool innermost layer.

That the outer layers shrink when cooled, resulting in pressure raising the temperature of the inner layers.

The inner layers now being hotter, the heat flows faster into the innermost layers and up the rod, cooling the inner layers for a replay.

This is replayed until there is no more gain. The gradient is flat.

I do not have an "answer" to this. What I have settled on is simply resistance.

Some theories (none to be taken too seroiusly)

The heat will move away from the cold as it is the path of least resistance to the temperature change.

The heat has already started "moving" the cold just heightens your awareness of the phenom.

The heat is afraid of the cold

My summer intern, (who happens to be female) tells me I forgot one.

The cold just doesn't understand the heat......

It's analogues to hydraulic flow through a pipe. Let us imagine a valve at one end and a pressure gauge at a distance. If we close the valve suddenly, the pressure gauge records a sudden shock/ kick, a momentary higher pressure. This is a real flow (however momentary it is) in the reverse direction, right?

In this comparison, what is equal to valve? The moment hot rod is immersed into water, heat stars to flow. But the steam generated at the rod's surface forms an insulator momentarily. This hampers the heat flow momentarily, which is like closing the valve in the pipeline. You can expect heat flow in the reverse direction for a moment, until the steam sheet gets away.

Re: Heat Being Repelled by Cold?

Initially skeptical, I thought about it and it occurred to me there might be a reason why this could be plausible.

The heat is not 'repelled' by cold, but thermal radiation can be reflected by a mirror.

There are 3 mechanisms for heat transfer: convection, conduction, and radiation.

In this case, we can ignore convection, since the iron itself is not moving (like hot air moves = convection). That leaves conduction and radiation. Clearly conduction is occurring, since the heat is moving through the iron.

But radiation can also be involved, as thermal photons can carry heat energy. Most people don't realize that ALL materials are 'optical' at some wavelength, and all materials are transparent (like glass) at some wavelength and thickness. So all materials have an index of refraction.

So - it may be that by quenching the end, you've temporarily changed the effective index of refraction. I.e., instead of 'seeing' super hot air at the tip of the iron, the thermal photons are suddenly seeing a cold, dense 'mirror' caused by the sudden drop in temperature and the thermal photons are reflected backwards.

Here's a simple sketch.

Yes, metals have an index of refraction, but only if we are talking very thin films, in the range 1-10nm. If the thickness is as much as 100nm then the transmission is virtually zero. Refraction is then no longer an issue, and is certainly not relevant to this hot rod. What the quenching does in your diagram is to limit the previous radiation from the end of the rod, and it also creates a new path for the conduction from hot area to cooler area.

Index of refraction is independent of thickness. That's the point. The attenuating properties of a material can be completely independent of the index of refraction.

Both ordinary soda-lime glass and obsidian have indices of refraction around 1.5. But an inch-thick piece of soda-lime is clear, whereas the same thickness of obsidian is opaque to visible light.

You can argue that the numerical value of the index of refraction is a property of a material which is independent of the thickness, but that value cannot be measured for metals in anything but a micrometer-thin film. If there is no transmission through a thicker slice there can be no refraction of that transmission, so the index of refraction is irrelevant to the discussion.

This sounds plausible....

I don't think you should ignore convection, as the steam surrounding the workpiece is very efficient at heat transfer and is being displace upward.

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More insight into both the hypothesis that steam is responsible for the heat transfer and the possibility of thermal radiation being reflected by a cooler area can be gained with a simple experiment comparing the effects of dipping in a bucket of water vs stabbing horizontally into crushed ice.

I have no explanation for the phenomenon of heat being repelled by cold. However, the case of the tinsmith 'packing heat' into the rod can be explained. When you heat the soldering iron and start using it to solder two pieces together the tip gets cooled because A) heat loss in the soldering operation B) heat loss due to convection by air surrounding the tip C) heat loss due to conduction to cooler part of the soldering iron. When initially 'packing heat' into the soldering iron you can heat the tip continuously only so much as otherwise the metal layer at the tip will get excessively hot and start to melt away. This could happen though Copper is a very good conductor of heat if the heat being put in by the flame exceeds that being carried away by conduction. So, if you heat the rod for a while till the tip is just hot enough and then dip it in water the tip is now ready to receive more heat and you can continue this heat / cool cycle till the whole of the rod is uniformly hot. Since it now holds more heat you can use it to solder more. Of course, this will hold good only for big rods.

I remember old soldering irons having a T shape end. They were constructed that way to make it easy to submerge the non active part in water.

Consider yourself that heat in the head.

Would you rather give yourself to a not very good heat conductor as water?

Or would you go and bring your heat up? (that part is also upright) Into the good metal heat conductor?

Same happens when you cool down a rod in water. You have been heating it up one one side just that long so that you can still hold it in your hand on the other side.

Once the hot side in the water, the heat moves to the part in your hand and you cannot hold it any longer.

What I have tried:Heating both rods to same temperature,at the same rate, and then timing how long it takes the heat to advance up the rod a measured distance up the rod, with both pieces side by side, neither rod being immersed in water.The time it took the heat to travel 1 foot up the rod was virtually identical in both cases.Now, I repeated the experiment,starting with both rods at same ambient temperature,and heated to same temperature, using a Templstik temperature indicator as a reference point. (Accurate to +- 1%, NIST traceable,see reference link below).I then immersed one rod end,2 inches of the hot end,at a 45 degree angle, into flowing water, from a water hose.Flowing water was used to prevent a steam pocket from forming around the end of the rod.

The rod was held at a precise 45 degree angle, as was the control rod,to eliminate other variables.

I did not immerse the second rod, it was left in the ambient surroundings.The difference in temperature was immediately noticeable.I had applied candle wax at a distance of one foot from the end of both rods.The wax from the water-immersed rod melted almost immediately,while the wax on the non-immersed rod remained solid for a very long (relatively) time.This experiment was performed with a very low budget,and will not survive,as is, to rigorous scientific criticism, but I feel confident that more precise methods will certainly verify my results.If I had the resources to control and monitor all variables,I would do so, but I feel that my results are worthy of a further time investment.More accurate results can be obtained, I am sure,using modern infrared photography,to show the real time progress of the heat up the rods.I will not give specific details on the timing or temperatures, or other controls of the experiment, as I may seek help to get my work published.I may have said too much already,but anything put on the internet lives forever,so this forum can document my first-at-bat here.As with the hot water freezes before cold water, it is an established fact, with no totally acceptable scientific explanation, but nonetheless,it is accepted as a valid occurrence. Perhaps this will be a similar assertion of a well known effect,that has been known for many years in metal working circles,but had not been scientifically verified,and as with the hot/cold water to ice, it was ridiculed by the scientific community as folklore.Those that laughed had to eat their words later.Thanks to all of those that critiqued my assertions,both good and bad, even those that ridiculed me; From them also I have learned much.I have never really learned much from those that always agreed with me.I was encouraged to develop a more scientifically palatable method,and finding a low budget way to do it. So, thanks to EVERYONE!

HiTekRedNek,

You know any kids who have to do a science fair experiment? Sounds like a good one to suggest.

--JMM

I do, and with HTRK's permission, I'll suggest this or a variation on it. How bout it, HiTek? Can I use it? I'll give you full credit, and report back here on the results.

Go for it.Anything that will help the next generation to think out of the box will ultimately help everyone.Permission granted.

I gave this some thought. Forgive me if someone has already suggested this (I didn't read all the posts ). Anyway, I think this may be a simple answer...

The Situation: You heat one end of a metal rod and then quench it, heat seems to go somewhat in the direction opposite from the part of the rod being cooled by the quenching liquid (water is assumed).

OK, remember that heat is conducted in any direction where there is a temperature differential. So, not only will heat be conducted toward the quenched end, but it will also be conducted in the opposite direction (the part you're holding) because that side of the rod is cooler than the heated part, as well.

Here's a possibility: Heat in the rod is being conducted by molecular motion-metal "atoms" banging against each other. Faster moving atoms bump slower moving atoms, making them move faster, and we see this as conducted heat.

However, if molecular motion in one part of the rod is being "actively" dampened by continued contact with a quenching medium, this might cause faster moving atoms to bounce elastically off the actively (continuously cooled) dampened atomic region. The motion of atoms that "have" bounced off would then be generally reflected in the direction of the rod's other end.

What do ya think?

Thank you, sir. With school being out here in the USA, it will be a long cycle. Assuming any of my students want to pick up on this next year, it will be next spring before I see any results. Don't try to hold your breath that long, but I'll be back to post results, if I get any of them to pick it up.

Good on YOU, and if you'd like to guest lecture my science fair students on how to develop a viable low-cost (student accessible) test method, and document the results, let me know. I'd love to have you demonstrate your thinking process, as that is the highest hurdle I face with most of my students. They love to learn, and don't mind thinking, but CSI and NCIS have convinced them that you can't do an experiment without pots of money.

Of course, I wouldn't mind pots of money. But learning something new on a shoelace is way more fun!

Wow...

For my part: 1. I know it happens, as I too have observed it. There is no misperception, trick, or illusion involved. For those that think so, they really need to try it. Hold the rod horizontally and jam it into cold water. Use a very long rod and a trough that can be entered from the side to clear all your doubts. It is not the steam that will burn you, just the metal grown insanely hot.

2. Convection involved? The heat is being moved by air?

No. I disagree. This is purely conduction. All of our materials are transferring heat by direct contact.

Radiation? No. No radioactive elements were used in my experiment.

Purely conduction.

3. Ideas why:

I agree that steam forms around the end being quenched. I agree that the steam acts as an insulator between the cold water and the red hot rod. I also agree that the metal very rapidly cools as it is quenched.

Metal is an excellent conductor. When the cold water becomes very hot steam from contacting the red hot end of the rod, the most cool area nearby is now the cold end of the rod. Previously, the cool room temperature air was a path for the heat to dissipate, as well as up the rod. Once the quenching began, the steam was a very hot, insulating are, and the heat moved up the cool section of the rod. It is still moving from hot to cold!! Just the other direction.

As more and more cold water is poured on, the heat would distribute throughout the rod - as it is a very good conductor, and eventually evenly cool.

I suspect the aforementioned tin smith's method worked similiarly- based on the distribution of the heat. In other words, the cool water allowed the heat to be distributed more fully through the iron.

Does heat move as a wave? I should probably google that- but I do not think that is necessarily important to the understanding. Heat is energy - excited molecules moving quickly. Materials all have a thermal conductivity. It's akin to the electrical resistance (though different) of materials.

The excellent thermal conductivity of the metal, I believe, is the culprit.

That's my bit. Flamers and trolls, flame on!

Anyone have some good thermal or multiphysics modeling software (COMSOL?) and the time/interest to do some analysis? It would be interesting to see a computer simulation of this phenomenon.

My latest theory of what is happening is:

When the hot metal contacts the cold flowing water,it immediately cools,and SHRINKS,from the outside inward,creating pressure on the inside,and with an increase in pressure,comes an increase in temperature of the inner layers.The compression also forces the molecules to shed some of their motion(heat) because there is not enough room to move about as freely in the now confined space.This results in a domino effect,that progresses up the rod like a wave travels down a whip.The added heat from compression and restriction make the end of the rod actually hotter,internally,that it was initially before applying the water.The basic laws of physics are not violated,because #1.: the heat moves from hot to cold.and #2: An increase in pressure results in an increase in temperature.

There was no steam boundary produced because the water was flowing.

This current theory is composed of several others that I have posted,and I feel is the best fit for the situation.As always, my mind is open for correction,and criticism.I only ask if you criticize, to provide a valid alternative theory.

If your steel rod is heated to red hot, you WILL have a steam boundary layer, and that steam will be attached and moving upward on large portions of the rod (especially the downstream portion).

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If you can feel the vibration from the quench then there is almost certainly a pocket of superheated steam transferring heat upward on the rod.

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Why not heat two similar steel rods to about the same temperature and dip one into a bucket at the same time you stab the other horizonally or slightly upward into a bag of finely crushed ice?

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If you can feel the vibration from the quench

That is just it, some states that that the steam acts like insulation, but that only happens when it's laminar...... it not, the vibration is turbulence.

You feel vibration when experiencing the Leidenfrost effect.

'Leidenfrost effect"

Thank you,

Back around 2007, I was called upon to design a convection tunnel pizza oven (100 pies/minute) for an OEM.

While I used fans to break up that insulating vapor area. A more aggressive and evenly spread technique is an impingement oven.

The physics involved was unbelievable interesting......... especially when you have several items to be baked with some being more heat sensitive than others.....

Hi HTRN!

As far as I can tell, look up or remember:
Heat moves more as a particle within a material, but on a high level scale, it looks like it is moving as a wave.

However - particles collide and reflect too! So that is not to say your previous comments about reflections are incorrect.

I do not think that pressure is the exaclty correct technical description, but I think your description above is at the very least an analogy for what is happening. The answer will, of course, be at the molecular level.

Someone said it before, but I think it was correct:
Then end that is cooled 'shrinks' - but also the molecules very rapidly slow. The fast moving hot molecules collide with the very slow ones, and reflect back toward the slow - but not as slow - other cold side, heating it up. As you say "progresses up the rod like a wave". Wave? Not sure - but maybe the exact description of motion isn't as important. I think particle (Pool balls colliding) - but we agree that it certainly moves up there!

I also agree that no laws of physics are, or ever were, violated - Even the dissenters early in this thread seemed to miss the obvious: The part of the rod held in the hand was always colder than the heated part! Lest we would be burning our hand right away, and the experiment end when we dropped it.

As to #2 - This is true, certainly, but I am not confident it applies here. I think focusing on the molecular collisions will be the best answer.

This:

"There was no steam boundary produced because the water was flowing."

I have to disagree. If the rod is heated to sufficient temperature, there will be steam. I agree that the boundary will not persist as water flows, and cooling occurs, but even a very brief microsecond of steam could be considered important when we are talking about molecular interactions and movements. However - I may simply be arguing wording here, hopefully not.

I would think:

Start - The highly excited (hot) molecules start in one end of the rod. The other end remains cool, since it was not heated. The air provides sufficient convection for heat transfer - so the heat continues to dissapate through the air.

Now we quench with flowing cold water:

The molecules in the hot end rapidly lose energy and become much more rigid. We create an elastic collision (like Vermin said!, ty). The pool ball like movement of the molecules sends the still ones both directions - toward the cold water, which continues to get slowed, and also toward our hand! The side toward our hand is cooler than the hot part, so heat moves from hot to cold still.

The movement of the heat may or may not be wave like instead. Either way - it "bounces off " the cooled end, and heads for the other.

Seem good?

I do not think that pressure is the exactly correct technical description,

I was thinking that stress is a better term....

The pool ball theory is analogous to my domino effect,of the molecular motion through the rod,where each molecule passes it's energy to the next lower-state molecule.The molecules themselves do not move, simply the energy moves between them.

Everything travels in a wave of one sort or the other.If you hit a steel rod on the end with a hammer, the force travels down the rod at a speed less than C.If it were instantaneous,it would have to break the speed limit of C.I know I am splitting hairs here,but it takes a sharp razor when working on the molecular level.

Heat is energy in the near-NIR,and NIR range (in this discussion.)Technically, it is molecular motion,which is present in all matter unless at absolute zero.

-----------------------------------------------------------------------------------

Which brings up another crazy idea of mine:The center of a black hole must be cold,for there is no molecular motion.In falling matter will emit heat, but once it reaches the singularity, all molecular motion ceases,(in fact, there are no molecules)and it builds up like snow on the surface of a sphere.In a sense, the black hole is laying down a chronological, serial-data stream recording of events.If we could unwind it,and play it back on some imaginary player, it would reveal everything that ever happened at the event horizon of the hole..The information is in effect, not lost,simply put into "cold storage". Hawking says that even a black hole emits energy,in what is called Hawking Radiation,due to one half of an entangled pair emerging inside the event horizon, and the other half outside of the horizon, which results in energy emission from the black hole,equivalent to the mass-to-energy conversion of the errant entangled particle, to" balance the books", so to speak.

Perhaps this should be marked off topic,for I have strayed a bit off of the main,so feel free to mark it as such if anyone feels the need.

I will try to substantiate my latest theory with some more experiments.

I intend to place a type K thermocouple in the end of the rod,in the center,so that I can detect the rise in temperature that I predicted when the end is quenched in running water. The problem I anticipate is the speed response may not be fast enough,or the A/D conversion quick enough to capture the event.It will take a while to round up all of the equipment needed,but I will let everyone know the results.

I would go with an infrared thermometer....instantaneous...here's one $23

http://www.amazon.com/Temperature-Infrared-Thermometer-Laser-Sight/dp/B002YE3FS4

Thanks for the link.

However,I want to measure the temperature at the core of the rod,which will be underwater,and this will not allow me to do that.

If heat can be defined as the amount of heat per unit volume,and the volume is suddenly restricted,the heat density increases,so it seeks a lower temperature, which in this case, is up the rod.I am pretty sure this theory holds water(pardon the pun). In this case, I would need to get a measurement at the core of the rod for maximum effect.The drilling of the hole, however, may affect the internal pressure during contraction and reduce the effect.If,however,I can show ANY increase in temperature, it will validate my idea.

Any ideas on how to make a good thermal bond between my thermocouple and the rod?

I would drill into the end of the rod, and use low temp solder to seal it...or maybe some of that conductive high temp paste used in cu-al connections...the thermocouple must be in good contact with the rod, the conductive paste may facilitate that....

The heat movement phenomena is the same in tubing.....

Thanks! I have some low-melt high silver content solder from 30 years ago,when silver was much cheaper than it is now.Silver is a very good heat conductor,so this will probably be the best solution.

I have an old digital temperature controller/indicator that still works,that is compatible with my thermocouple,so I can use it for this purpose.

When I get everything set up,I intend to test the rod with different temperature water baths to see if it affects the rate of heat leaving the hot end.

Going to be a while with the holiday coming up, but I will keep posting my progress.

Most steel has a coefficient thermal of expansion of about 0.0000006/deg F

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So if the piece was cherry red (~1400 F) and it cooled all the way to 200 F, the reduction in linear dimension would still be well short of 1%. My guess is that the heat lost in the quench would more than offset any increase resulting from less than 1% linear reduction (well less than a 3% reduction in volume).

Good Point! You may be right,and probably are,considering the info you just presented,so I may have to develop another scenario of what is going on.I am going to give it a rest for a while till I get more data from my next experiment.

If you are in the USA,have a happy and safe 4th of July.

Don't drink and drive, stay alive.

As my wise old uncle used to say:"He who goes forth on the fourth with a fifth may not come forth on the fifth!"

I can't help thinking the answer/explanation is in this page. I think it is basically a boundary issue. The boundary at the end of the rod changes from air to water, each with its specific heat flow, which, by changing, influences the heat flow in the rest of the metal rod. Sorting this out via the math and presentation on this page is daunting. I always disliked the formality of math texts.