# What is heat? **URL:** \ **Category:** Great Debates\ **Created:** [March 3, 2006, 1:28am UTC](https://boards.straightdope.com/t/what-is-heat/346850 "2006-03-03T01:28:10Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![smurfslappa](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@smurfslappa](https://boards.straightdope.com/u/smurfslappa)\ **Post date:** [March 3, 2006, 1:28am UTC](https://boards.straightdope.com/t/what-is-heat/346850/1 "2006-03-03T01:28:10Z")
We can measure it, we know it makes particles vibrate. What is it exactly, though? Discuss. ---
**Author:** ![Hostile\_Dialect](https://avatars.discourse-cdn.com/v4/letter/h/e495f1/32.png) [@Hostile\_Dialect](https://boards.straightdope.com/u/Hostile_Dialect)\ **Post date:** [March 3, 2006, 1:29am UTC](https://boards.straightdope.com/t/what-is-heat/346850/2 "2006-03-03T01:29:49Z")
The random motion of molecules. ---
**Author:** ![smurfslappa](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@smurfslappa](https://boards.straightdope.com/u/smurfslappa)\ **Post date:** [March 3, 2006, 1:39am UTC](https://boards.straightdope.com/t/what-is-heat/346850/3 "2006-03-03T01:39:57Z")
Riiiiight. I think it’s a little more than that… ---
**Author:** ![Tevildo](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Tevildo](https://boards.straightdope.com/u/Tevildo)\ **Post date:** [March 3, 2006, 1:44am UTC](https://boards.straightdope.com/t/what-is-heat/346850/4 "2006-03-03T01:44:00Z")
Not really. “Heat” is just energy that’s transferred at a microscopic level, rather than a macroscopic level (such as pushing on something). It’s only a question of size, “heat” and “energy” are identical otherwise. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [March 3, 2006, 2:03am UTC](https://boards.straightdope.com/t/what-is-heat/346850/5 "2006-03-03T02:03:47Z")
This is easily demonstratable too, heat up air in a balloon and it expands, same amount of molocules in the balloon, just moving faster and with more “energy.” It is also the reason why there are three of the forms of matter. Solid (motion is low), Liquid (motion is high, but not high enough to break away), and gas (motion is sufficient for molcules to break away from each other) ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [March 3, 2006, 2:09am UTC](https://boards.straightdope.com/t/what-is-heat/346850/6 "2006-03-03T02:09:52Z")
On the very lowest level of explanation I think heat is that form of energy that raises the temperature of physical objects. Temperature is a measure of the average kinetic energy of the molecules that make up the object. It seem clear then that heat is the motion of the molecules. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [March 3, 2006, 2:17am UTC](https://boards.straightdope.com/t/what-is-heat/346850/7 "2006-03-03T02:17:30Z")
> [@smurfslappa](#): > > We can measure it, we know it makes particles vibrate. What is it exactly, though? Discuss. Heat is a form of energy associated with the motion of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation. Heat energy is transferred from one body to another when it resulsts in a difference in temperature or a change in phase. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [March 3, 2006, 5:00am UTC](https://boards.straightdope.com/t/what-is-heat/346850/8 "2006-03-03T05:00:42Z")
And it’s very easy to transform macroscopic motion (what we think of as kinetic energy) to microscopic motion (what we think of as heat). Just rub your hands together. The friction caused by moving your hands causes the molecules in your hands to move faster…and they get warm. ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [March 3, 2006, 5:40am UTC](https://boards.straightdope.com/t/what-is-heat/346850/9 "2006-03-03T05:40:03Z")
And vice versa, although it’s not quite as obvious. Anything that “generates” electricity (i.e. electrical energy) has to do so by converting some other kind of energy. In some cases, this is heat energy. Thermal energy can also be converted into chemical energy (fire, photosynthesis, etc). I hope I didn’t make some glaring scientific error. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 3, 2006, 7:28am UTC](https://boards.straightdope.com/t/what-is-heat/346850/10 "2006-03-03T07:28:06Z")
> [@smurfslappa](#): > > Riiiiight. I think it’s a little more than that… No, that pretty much sums it up. Heat is a non-directional form of energy; the only way you can get it to perform actual work is by offering a volume of “heat” a low temperature reservoir in which to direct itself (and in the process, convert some of that energy into a vector form). When people speak of the heat-death of the Universe they mean the point at which there are no remaining temperature differentials by which to effect a thermodynamic occurance. It’s also, in metaphorical form, a rather good movie by Michael Mann. “Don’t let yourself get attached to anything you are not willing to walk out on in 30 seconds flat if you feel the heat around the corner.” Stranger ---
**Author:** ![Nancarrow](https://avatars.discourse-cdn.com/v4/letter/n/c37758/32.png) [@Nancarrow](https://boards.straightdope.com/u/Nancarrow)\ **Post date:** [March 3, 2006, 12:09pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/11 "2006-03-03T12:09:09Z")
> [@smurfslappa](#): > > We can measure it, we know it makes particles vibrate. What is it exactly, though? Discuss. I think your problem is a semantic one. Try this: Heat does not CAUSE particle vibration. Heat IS particle vibration. ---
**Author:** ![smurfslappa](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@smurfslappa](https://boards.straightdope.com/u/smurfslappa)\ **Post date:** [March 3, 2006, 2:42pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/12 "2006-03-03T14:42:32Z")
Nope, that’s a gross oversimplification of it. The vibrating particles are the observed effects of it, not what it actually is. Just like electricity isn’t necessarily electrons itself, but can flow through a column of electrons. There is more to this energy than meets the eye… ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [March 3, 2006, 2:51pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/13 "2006-03-03T14:51:05Z")
> [@smurfslappa](#): > > Just like electricity isn’t necessarily electrons itself What is it then, other than the flow of negatively charged particles called electrons? (And yes, I know about ‘holes’ in semi-conductors: they’re a gross oversimplification themselves). ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [March 3, 2006, 5:42pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/14 "2006-03-03T17:42:41Z")
Actually, electricity really is just electrons moving. Vibrating particles aren’t an observed effect of heat, they ARE heat. You asked for our input. If you disagree with the answers, you should at least try to explain why you think we’re wrong, rather than just assert we’re wrong. ---
**Author:** ![EEMan](https://avatars.discourse-cdn.com/v4/letter/e/a6a055/32.png) [@EEMan](https://boards.straightdope.com/u/EEMan)\ **Post date:** [March 3, 2006, 5:52pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/15 "2006-03-03T17:52:44Z")
To be fully technical… Electricty is simply the existance of different numbers of electrons at different locations… as described by voltage (or potential)… current is the flow of those electrons and is the ‘other’ aspect of electricty… But electricty doesn’t ‘flow through’ electrons… that is for sure… and the ‘effect’ of heat, isn’t vibrating particles… but rather temperature… or the ‘flow’ of heat… ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [March 3, 2006, 5:59pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/16 "2006-03-03T17:59:05Z")
How about: Heat is the energy that is left over in a system after all of the other forms of energy have been accounted for and it results in an increase in system temperature. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 3, 2006, 7:03pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/17 "2006-03-03T19:03:14Z")
> [@EEMan](#): > > Electricty is simply the existance of different numbers of electrons at different locations… as described by voltage (or potential)… current is the flow of those electrons and is the ‘other’ aspect of electricty… > > But electricty doesn’t ‘flow through’ electrons… that is for sure… There’s a nomenclature and semantic problem with “electricity”, insofar as people use the term to describe wildly varying phenomena. As far as electrical current in wires, the popular image of little electrons tunnelling their way through the wire is completely wrong, but very common. > [@EEMan](#): > > and the ‘effect’ of heat, isn’t vibrating particles… but rather temperature… or the ‘flow’ of heat… > [@David Simmons](#): > > How about: Heat is the energy that is left over in a system after all of the other forms of energy have been accounted for and it results in an increase in system temperature. Careful, guys. Neither of these statements is strictly wrong, but it’s a very common mistake to conflate the concept of heat with that of temperature; people get the notion that “temperature” is a measurement of heat in a system, which isn’t precisely true. Temperature is a relative measure of the thermodynamic equilibrium of two systems (or a system and the external universe). Without a referent–ultimately (in practice) the 2.7K microwave background of space–temperature has no strict meaning, or at least value, though it is true that at 0K a system is at its minimum possible energy level. Heat, on the other hand, is an absolute measure of the latent or nondirected energy of a system. One system can have more total “heat” but a lower temperature, and will therefore receive heat from a system with less energy but a higher temperature. That seems counterintuitive in terms of normal experience–things we encounter that have a high temperature are also very hot–but it is possible to have something that has a very high temperature and which yet contains little heat, like the Shuttle insulation tiles after reentry, which glow red-hot but can be held in an unprotected hand. Stranger ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [March 3, 2006, 8:02pm UTC](https://boards.straightdope.com/t/what-is-heat/346850/18 "2006-03-03T20:02:19Z")
> [@Stranger On A Train](#): > > … it is possible to have something that has a very high temperature and which yet contains little heat, like the Shuttle insulation tiles after reentry, which glow red-hot but can be held in an unprotected hand. > > Stranger Or the temperature of the atmospheric thermosphere at an altitude of about 60 to 125 miles where the temperature varies from around 600 C to around 2000 C depending upon sunspot activity. Nevertheless the addition of heat does result in an increase in temperature and the loss of heat does result in a lowering of temperature. Taking your case of something having a lot of heat but a low temperature let’s take a bucket of water weighing 30 lb. at 20 C. For the thing that doesn’t have much heat but a high temperature let’s take a 10 X 10 X 10 ft. room full of argon gas at 100 C. Put the bucket in the room and the water will warm up some while the argon will cool down quite a bit. The final temperature will be 44.41 C, the water having gained 24.41 C and the argon having lost 55.59 C. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [March 5, 2006, 12:35am UTC](https://boards.straightdope.com/t/what-is-heat/346850/19 "2006-03-05T00:35:55Z")
Heat is the interaction of a deniron and pacinon.