What is temperature?

[Kljoki]

?

[Xenophon]

It's a measure of the internal kinetic energy of something. IE how fast the molecules that compose a substance are moving around.

[Kljoki]

So there is no temperature if there is no substance?

[Snowflake]

The kinetic energy of the molecules in a substance. The faster they move, the higher the measured temperature and vice versa.

[Snowflake]

So there is no temperature if there is no substance?

Correct.

[Kljoki]

So if temperature is kinetic energy then there is no movement without substance?

[Snowflake]

Velocity and speed are metrics which are applied to matter or systems of matter.

[Xenophon]

So there is no temperature if there is no substance?

To explain this a little more. Human's don't actually feel temperature. They feel heat transfer. So, why does it feel colder on a day when there is more wind? It is because heat leaves our body quicker with more advection, the air temperature isn't actually colder.

[Xenophon]

So if temperature is kinetic energy then there is no movement without substance?

What would be moving?

[Kljoki]

What would be moving?Space.

[Snowflake]

Space.

Space doesn't move.

Space is space, is the area which matter is contained in.

[Xenophon]

Space.

No, Space doesn't move. There is no way that you could differentiate between one piece of space and another.

[Snowflake]

Correct, velocity is defined as the change in distance over a period of time.

This means you have to have a frame of reference with which the object is relative to, in order to measure the distance the object has moved.

[Hustler]

T = (PV)/(nR)

[Kljoki]

Correct, velocity is defined as the change in distance over a period of time. If you bend space, the distance changes. Isn't that a change of distance over time?

[Kljoki]

T = (PV)/(nR)More as an abstract concept.

[Snowflake]

If you bend space, the distance changes. Isn't that a change of distance over time?

No. The reference plain is linear. There is no way to know whether space is bent or not. Also, a bend in space doesn't necessarily corrolate to a movement of the object.

[Kljoki]

No, Space doesn't move. There is no way that you could differentiate between one piece of space and another.Are you sure?

[Kljoki]

No. The reference plain is linear. There is no way to know whether space is bent or not. Also, a bend in space doesn't necessarily corrolate to a movement of the object. Two point in space. One is a reference point. By bending space we move them closer. We perceive this as a change of distance over time.

[Snowflake]

Space is space, dude. Can you tell one piece of air from another?

[Snowflake]

Two point in space. One is a reference point. By bending space we move them closer. We perceive this as a change of distance over time.

Like I said, that isn't necessarily true.

[Kljoki]

Space is space, dude. Can you tell one piece of air from another? Just because I can't doesn't mean it's not different.

Also, a bend in space doesn't necessarily corrolate to a movement of the object.Bending space does. It changes the distances involved.

[Snowflake]

No, because space isn't used as the reference frame.

[Kljoki]

No, because space isn't used as the reference frame.And what is?

[Snowflake]

The imaginary construct which is created at a fixed point in space. From this point, you measure distance. This distance is always relative to the fixed point.

The point doesn't have to be stationary, for example, in the case of relative motion, where you might want to know the speed of one object relative to another. E.g., driving on a highway, the car in front of you would have a relative speed of roughly 0 km/h relative to you, while you would have a speed of say, 100 km/h relative to a "stationary" road sign that you pass.

The reference plane is assumed to be linear, which each axis orthogonal to the other two. For the above example, you'd only need to measure velocity in one dimension.

[Kljoki]

The imaginary construct which is created at a fixed point in space. From this point, you measure distance. This distance is always relative to the fixed point. Place two singularities as two reference points.


The point doesn't have to be stationary, for example, in the case of relative motion, where you might want to know the speed of one object relative to another. E.g., driving on a highway, the car in front of you would have a relative speed of roughly 0 km/h relative to you, while you would have a speed of say, 100 km/h relative to a "stationary" road sign that you pass. Now apply this to the two singularities.


The reference plane is assumed to be linear, which each axis orthogonal to the other two. For the above example, you'd only need to measure velocity in one dimension.You don't have to.

[Snowflake]

.

[Snowflake]

I deleted my previous reply, but I am confused as to what you're getting at.

[Kljoki]

I am confused as to what you're getting at. Imagine two (Mathematical) singularities. You can use them as reference points in space as they convey the curvature of space and have no substance (In space). If you twist space you "move" these singularities.

[Xenophon]

No, because mathematical singularities don't exist. Therefore they have no temperature.

[Kljoki]

No, because mathematical singularities don't exist. Therefore they have no temperature. [Have not been observed] But space does. If it has movement it has kinetic energy. The singularities would move *with* space.

[Snowflake]

[Have not been observed] But space does. If it has movement it has kinetic energy. The singularities would move *with* space.

Singularities don't have temperature.

Like I said before, temperature is the movement of molecules WITHIN A SUBSTANCE.

Space does not consist of matter, and therefore has no temperature. It is a vacuum.

[Xenophon]

Ok, this is the last time I'm gonna post unless you write something with a little substance in it.

What do you mean by a mathematical singularity? A Singularity in math is just a point where the derivative doesn't exist. Having a mathematical singularity in space doesn't mean anything.

Mathematically speaking, ke = m*v^2/2, ie kinetic energy is the product of mass and velocity squared. Does space have mass?

Could you just tell me the point of this thread? Are you trying to argue against our definition of temperature? Are you trying to prove that something without mass can have a temperature? I don't get it.

[Xenophon]

Singularities don't have temperature.

Like I said before, temperature is the movement of molecules WITHIN A SUBSTANCE.

Space does not consist of matter, and therefore has no temperature. It is a vacuum.

I think that Kljoki has just proved that a post without substance can generate heat. Incredible.

[Snowflake]

:rofl:

If a singularity by his definition is something like a black hole, then a black hole has a huge mass. But it doesn't fold space or anything like that. The temperature on the other hand, I'm not willing to estimate.

[Kljoki]

What do you mean by a mathematical singularity? A Singularity in math is just a point where the derivative doesn't exist. Having a mathematical singularity in space doesn't mean anything. I'm just using it as a way to show the contortion of space, like adding smoke to see the flow of wind.
Mathematically speaking, ke = m*v^2, ie kinetic energy is the products of mass and velocity squared. Does space have mass?Does a photon have mass? Your question is ridiculous.
Could you just tell me the point of this thread? Are you trying to argue against our definition of temperature? Are you trying to prove that something without mass can have a temperature? I don't get it.
Hmmm, there really is no point. I'm learning about the nature of temperature from your responses to my questions. Forming hypothesis along the way. Here's what I have so far

Let's say heat is kinetic energy. Everything that possesses heat would have kinetic energy. I'm wondering if space possesses kinetic energy. If it is a property of space.
You define kinetic energy as movement. Movement is a change of distance over a period of time. Matter moves, substance moves. But gravity distorts space and thus *moves* space. Because it changes the distances within space. We have a change of distance over a period of time. Thus movement. Thus kinetic energy. And possibly heat.

[Kljoki]

I think that Kljoki has just proved that a post without substance can generate heat. Incredible.More like a difference of opinion. But that is already known.

[Snowflake]

Let's say heat is kinetic energy. Everything that possesses heat would have kinetic energy. I'm wondering if space possesses kinetic energy. If it is a property of space.
You define kinetic energy as movement. Movement is a change of distance over a period of time. Matter moves, substance moves. But gravity distorts space and thus *moves* space. Because it changes the distances within space. We have a change of distance over a period of time. Thus movement. Thus kinetic energy. And possibly heat.

:rolleyes2

Have you been listening?

Heat is NOT merely kinetic energy. Kinetic energy is kinetic energy, not simply movement.

Gravity does not distort space, or cause kinetic energy.

Gravitational forces between two objects creates a gravitational force of attraction, which can be responsible for movement, but it doesn't have to be.

Heat is not related to the kinetic energy of a body. It is related to the kinetic energy of the molecules within the SUBSTANCE of the body. The substance being the molecules that make up the structure.

Space does not have mass, and hence no temperature. Space is a vacuum.

[Snowflake]

More like a difference of opinion. But that is already known.

If you want to disregard the laws of science, you are welcome to. But these are not debateable entities. Science is as science does.

[Xenophon]

Good point about photon. However, they are a wierd case, as they are constantly moving at the speed of light, due to relativity this throws a wrench into the whole damn problem. I don't really understand it, so I can't comment further.

Another point. Heat and Temperature are different things. Heat is the transfer of energy, temperature is the internal energy stored in something.

I don't think you really understand Einstein's theories when you are using them like this. However, I don't really understand them either, so I can't really correct you. This is always a problem when someone tries to explain a scientific theory like relativity to laymen like us. They have to use words that we understand, however while they use the term "bend space", that is not a literal description, it is figurative to help you understand intuitively what is happening. Trying to redefine energy based on a term like that is almost sure to provide you with incorrect results.

[Kljoki]

Heat is not merely kinetic energy. Kinetic energy is kinetic energy, not simply movement.Then what is heat other then kinetic energy?
Gravity does not distort space, or cause kinetic energy.Are you sure that gravity doesn't distort space? How do you explain black holes then?
Gravity causes movement and potential energy.
Heat is not related to the kinetic energy of a body. It is related to the kinetic energy of the molecules within the SUBSTANCE of the body. The substance being the molecules that make up the structure.Molecules would be the the body then.

Space does not have mass, and hence no temperature. Space is a vacuum.What if it has structure?

[Kljoki]

If you want to disregard the laws of science, you are welcome to. But these are not debateable entities. Science is as science does.What if they are wrong?

[Kljoki]

Good point about photon. However, they are a wierd case, as they are constantly moving at the speed of light, due to relativity this throws a wrench into the whole damn problem. I don't really understand it, so I can't comment further.

Another point. Heat and Temperature are different things. Heat is the transfer of energy, temperature is the internal energy stored in something.

I don't think you really understand Einstein's theories when you are using them like this. However, I don't really understand them either, so I can't really correct you. This is always a problem when someone tries to explain a scientific theory like relativity to laymen like us. They have to use words that we understand, however while they use the term "bend space", that is not a literal description, it is figurative to help you understand intuitively what is happening. Trying to redefine energy based on a term like that is almost sure to provide you with incorrect results. Wormholes are a prediction of his theory. Of changing the distance.

According to me, a changing gravity field would produce an energy field. Just like Maxwell's changing electromagnetic field.

EDIT: All I'm claiming is that distorting space causes energy.

[Snowflake]

What if they are wrong?

Perhaps, but they are in the hands of people far more capable than I am.

Besides that, it's really a poor excuse to just start changing things at whim.

[Kljoki]

Perhaps, but they are in the hands of people far more capable than I am.

Besides that, it's really a poor excuse to just start changing things at whim.:lol:

And what "excuse" would you use?

[Snowflake]

:lol:

And what "excuse" would you use?

The excuse I would use would be based on more evidence that the theories are wrong than simply wanting to change things around because I didn't understand how they worked in the first place.

Of course, this would make me guilty of being hypocritical, but what else is new?

[Kljoki]

The excuse I would use would be based on more evidence that the theories are wrong than simply wanting to change things around because I didn't understand how they worked in the first place.I never changed a single theory.

[Snowflake]

Wormholes are an prediction of his theory. Of changing the distance.

According to me, a changing gravity field would produce an energy field. Just like Maxwell's changing electromagnetic field.

EDIT: All I'm claiming is that distorting space causes energy.

Space does not create energy, sorry.

Energy is always conserved. No new energy is ever created.

[Melody]

we dunno if a 'photon' is massless


---------------------
the way i see it [and possibly what snowflake was sayin]:

picture 2 objects in space, we could say it looks like:

http://img.photobucket.com/albums/v259/tocca/ena/space0101010324242342.gif


now, assuming 'space' even allows distortion; when we compress it, it would look like:

http://img.photobucket.com/albums/v259/tocca/ena/space2341411123498777.gif


the 'distance' between the objects [from their perspectives] does not change

however, in relativity, gravitational waves are waves of spacetime, not just space, so the actual situation prolly isnt as simple considering spacetime is not euclidean. but im just getting seriously started in learnin these theories so w/e

is heat possible from this? iono. im hungry tho!

[Snowflake]

we dunno if a 'photon' is massless

A photon is a particle of energy, it has no mass.

[Melody]

u dare go against the legendary somethin or other????

lol; we dunno if its massless, or just incredibly light

[Snowflake]

mass isn't the same as weight, merely proportional to it.

[Melody]

so?

[edit]by light i do not mean 'of minimal weight,' i mean 'of minimal mass'

also, weight =/= mass is incredibly fucking trivial; who u think i am??!!! *pulls hair out*

seriously tho, dont take my statements lightly

[Snowflake]

so?

[edit]by light i do not mean 'of minimal weight,' i mean 'of minimal mass'

also, weight =/= mass is incredibly fucking trivial; who u think i am??!!! *pulls hair out*

seriously tho, dont take my statements lightly

Uhm, right.

:blink:

[Google Monster]

:rofl:

[Snowflake]

I never changed a single theory.

No, you're rabidly misinterpreting them and/or coming up with your own.

[Superstring]

Heat is a form of electromagnetic radiation....(etc)

[Melody]

Uhm, right.

:blink:for example, my statement about photons is not 1 i pulled out of my ass to talk bullshit. we really dont know if they are massless

[Xenophon]

Heat is a form of electromagnetic radiation with a wavelength just a tiny bit larger than its nearest relative in the EM spectrum; visible light (which is why you can see heat with the right kind of goggles). Heat waves cause vibration in atoms, which is what feels warm to us.

Actually, this is wrong. You are talking about the infra-red spectrum. Heat can be transferred through radiation, but you cannot classify it as a particular spectrum of radiation. In fact, all radiation is heat, as it transfers energy from one substance to another in the form of photons. Though, even if we expanded the definition of heat to include all radiation, it would still be incomplete, as you wouldn't be taking into account conduction and convection.

What probalby confused you is this: Things in a typical temperature range that you would find on earth emit radiation at a temperature lower than visible light. So, with special goggles, you can indeed see the radiation emitted from an animal. However, if something is really hot, you don't need goggles at all to see it. The reason we can see fire is because it is generally at a temperature where it emits radiation in the visible range. However, some things when burning are so hot that you can't even see them: like a hydrogen fire. It is completely undetectable for the human eye, but it would hurt like hell to walk into one.

[Superstring]

Oi! Thanks for the prompt correction Xenophon, don't I just suck..

[NoahFence]

Heat is kinetic energy, but it is a very specific form of kinetic energy. In particular, it is known as "random kinetic energy".

Imagine a boulder. Push it, watch it roll down the hill. What happened? All sorts of kinetic energy just went down. Your muscular contraction is not heat. The boulder rolling down the hill due to gravitational attraction is not heat. The shockwave of its impact at the bottom is not heat. Note that all of these things may actually add heat to the system, though.

Heat is the molecules within the substance "quivering". The hotter it gets, the more they quiver. At Absolute Zero, they stop moving altogether. If you can imagine a huge array of balls hung together by springs, you'll get some of the picture. If I take a baseball bat and smack the crap out of it, the balls all jump and jiggle and wobble for a while. Note that no matter whether the array is "hot" (jiggling like mad) or "cold" (little jiggling), I can still pick the whole thing up and chuck it off a cliff. When this jiggling becomes pronounced enough, i.e. more heat is added to the system, the molecules are so excited that they start breaking their springs and the substance either melts (if it was solid) or boils (if it was liquid).

Now, as for whether space can have temperature, the answer is no. Temperature is directly a measure of the random kinetic energy present in a sample of matter...it specifically deals with how fast the molecules are doing the jitterbug...no matter, no temperature. Unless you want to argue about dark matter being considered "space", the best you can hope for is some kind of energy which could impart heat should any matter swing by.

[Snowflake]

Oi! Thanks for the prompt correction Xenophon, don't I just suck..

To be honest, I almost did the same thing.

You weren't wrong, just not precise. Not that it really matters in this thread, heh.

[NoahFence]

It's also worth mentioning that "heat" and "temperature" are not the same thing.

Heat is defined as the total random kinetic energy of the molecules in a sample of matter.

Temperature is defined as the average random kinetic energy of the molecules in a sample of matter.

A cup of coffee has a notably higher temperature than the ocean, but has far less heat.

[lbloom]

Some remarks on NoahFence's posts:

"At Absolute Zero, they stop moving altogether"

Scientific trivia - not really. Can be shown to be a consequence of Heisenberg's uncertainty principle.

"Heat is defined as the total random kinetic energy of the molecules in a sample of matter" and "...but has far less heat" are incorrect - heat is an informal name for "heat transfer" and is energy in transit: a system (or substance, if you like) does not "contain" heat. You are thinking of "heat capacity" as used in high school science text-books. The use of the word "heat" in "heat capacity" is technically suspect: that quantity is related to internal energy and enthalpy, and is closer in spirit to temperature than heat, and it depends upon the state (or precise thermodynamic conditions) of the substance.


Nice physical explanation of molecular energy.

[Edmond Zedo]

Gravity does not distort space
Are you sure?

[Snowflake]

Are you sure?

lol :offtopic:

But seriously, nope.

[lbloom]

temperature is or might be more accurately determined by inherent environment than by any scientific simulation.
Given a pure substance, i.e. one with a uniform, known chemical composition, temperature can be simulated to a very high degree of accuracy. That's what statistical thermodynamics is all about.

[Nemesis]

To be quite blunt:

A few hours ago it was 80°.

Now its closer to 55°.

...Yeah. Wake me when the average tempurature is once again 75°<_<

[indie]

Given a pure substance, i.e. one with a uniform, known chemical composition, temperature can be simulated to a very high degree of accuracy. That's what statistical thermodynamics is all about.

"to a very high degree of accuracy"

:lol:

I deleted my post in this thread because I realized I wasn't attempting to answer the question of "what is temperature?" More like "what is a degree?" -- entirely contextual.

[lbloom]

;) Didn't notice that.

Interesting fact: space has a temperature signal (~2.72 Kelvin) that is a remnant from the big bang. This is the primary means for an estimation of the age and size of the universe.

[Snowflake]

How can space have a temperature if there is no mass?

[Melody]

prolly radiation, so not exactly temperature http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation

...tho, since theres no certainty about the masslessness of elecromagnetic waves... uniform-ish background radiation could have something like the formal definition of temperature if the thingies have mass

i wouldnt say that would make em much different tho, its still stuff in the background thatll create temperature upon interacting w/ mass either way

[Xenophon]

Yeah, things radiate energy at epsilon*t^4 or something like that (i forget the exact equation). So I suppose you could look at the background radiation of the universe as a temperature.

[ben from below]

there's lots of yummy fallacies going on in this post that I want to comment on, if anyone still cares about this old thread, but I'm so very tired.

a few quick things:

1. gravity doesn't distort space. Gravity IS distorted space. That's general realtivity.

2. A single unconfined object doesn't have a well defined temperature. Temperature, technically is defined as follows: 1/T = dS/dE, where S is the Entropy and E is Energy. Entropy is related to the number of distinct states an object can be in, so temperture has to do with how the number of available states changes with energy. A single, unrestrained object...uggh...i don't wanna think about it...

3. "Space" as in outer space, has a tempature due to the background radiation. While photons don't have mass as far as anyone knows, they do carry kinetic energy, and there's a bunch of 'em out there, so they have entropy, so dS/dE is defined...space has temperature.

If there's any more interest, I'll post more later...so...sleepy

[lbloom]

http://www.lhup.edu/~dsimanek/hell.htm

[NoahFence]

3. "Space" as in outer space, has a tempature due to the background radiation. While photons don't have mass as far as anyone knows, they do carry kinetic energy, and there's a bunch of 'em out there, so they have entropy, so dS/dE is defined...space has temperature.

I fail to see how space suddenly gains temperature by photons being present. Matter is present in space, too. Space is defined as the part of that volume you're measuring that is -not- photons. Coudl not a volume exist which had no photons or other particles present?

Ditto for the background radiation of the big bang. The radiation consists of particles moving through space, no? It is not space itself which has that temperature, but the particles.

[Xenophon]

I fail to see how space suddenly gains temperature by photons being present. Matter is present in space, too. Space is defined as the part of that volume you're measuring that is -not- photons. Coudl not a volume exist which had no photons or other particles present?

Ditto for the background radiation of the big bang. The radiation consists of particles moving through space, no? It is not space itself which has that temperature, but the particles.
No, it is called "background" radiation because it doesn't originate from matter. The frequency of the radiation (photons) emitted from something is proportional to it's temperature. They say that space (even with no matter in it) emits radiation at a very low frequency. I don't know how they determined this, but that is what they say.

[meshou]

EDIT: All I'm claiming is that distorting space causes energy.No, I believe that voilates several laws of thermodynamics. Nothing can create energy.

As I understand, heat is a measure of the total energy of a substance. Temperature is a number proportional to the average kinetic energy in the space taken.

So, patches space, which is anything but empty, may have astronomical heat, but be very close to zero Kelvin in temperature. Or, a log and a burning log's heat don't vary nearly as much as their temperature.

[lbloom]

So, patches space, which is anything but empty, may have astronomical heat, but be very close to zero Kelvin in temperature.

:huh: Care to try and articulate your thoughts on that better? Esp. astronomical heat.

[meshou]

:huh: Care to try and articulate your thoughts on that better? Esp. astronomical heat.Sure. Heat = ALL energy in a thing, including potential. Potential energy is like the energy locked in an atom, or a slinky at the top of a staircase, or an unburned log, or radiation in a space with no atoms to convert it to kinetic energy.

Since there's quite a lot of radiation in certain patches of empty space with few or no atoms to interact with (midway between the earth and the sun, say), it has a lot of heat, but low temperature. However, if we popped a chicken into existance there, it'd suddenly be a crispy critter.

The numbers we use to measure temperature aren't direct measures of anything, but are numbers proportional to the amount of kinetic energy being used in a given area. An atomic bomb goes off, the slinky falls down, we torch the log, light interacts with our atmosphere and excites the molecules in it. In all those instances, the temperature has gone up in the area where the work is being done (not much in the case of the slinky, but still).

[lbloom]

Ah. You're talking about detection of the radiation by placing a sensor (i.e., the poultry) in its path. Like you need dust particles to tell whether or not there's light streaming into a dark room.

The ~3K temperature that is talked about does not involve matter being in it's path.

A body at a certain temperature will emit radiation with a dominant frequency corresponding to its temperature. So that radiation, when detected elsewhere (even after it has passed through vacuum), will reveal the temperature of its origin. You don't need to fry an object for this, an antenna tuned to the right frequency range will allow detection, and then the exact frequency isn't hard to find. It's just radiation permeating all of space.

Now suppose there was this event called the Big Bang a long time ago. Based on the (really basic) chemistry that theorists believe existed at those early points in time, they have an estimation of the original temperatures. As the universe expands and ages, there has been an exponential decay of that temperature. If you could now "read" that barely-there signature of that temperature signal now, you could figure out how long it has been. Like the radioactive decay problems in school.

I've stuck to the classical wave nature of radiation since it's more intuitive, and quite sufficient in this case.

If you folks want to discuss the photon as a particle, I suggest you make your peace with this one, decouple and consider that issue separately.

[meshou]

...I was merely talking about the difference between temperature and heat while refrencing some things talked about in this thread. Yes, the temperature at the time of the big bang was both high and something that can be estimated. But I think that making the distinction between heat and temperature that there can be a lot of heat in a vaccum while the temperature hovers near zero kelvin is a good way to explain the difference.

[lbloom]

Heat is energy in transit. Things don't "have" heat in isolation, it's a mode of energy transfer.

[meshou]

Heat is energy in transit. Things don't "have" heat in isolation, it's a mode of energy transfer.Good lord. Re-phrase my phrasing to say "there can be a lot of energy transfer in one patch of space and not alot in another without any difference in temperature between the two," which is basically what I've been saying to illustrate the difference, and I am absolutely correct. Are you going to explain to me the finer points of sucking eggs next, or can I look forward to more nit picking of points I obviously understand?

[lbloom]

Are you going to explain to me the finer points of sucking eggs next, or can I look forward to more nit picking of points I obviously understand?

:smooch: Some more.

"there can be a lot of energy transfer in one patch of space...": between that patch and what other entity? If it's all at the same temperature, then there is no heat transfer.

[meshou]

"there can be a lot of energy transfer in one patch of space...": between that patch and what other entity? If it's all at the same temperature, then there is no heat transfer.Do "given" and "adjascent" look like the same word to you? Of course all of space can't be a uniform temperature, or else it wouldn't HAVE a temperature.

Let's use another example, since we're getting bogged down by the kiddie physics squad: semantics division. Ice and ice the moment after meltine are the same temperature (that is, they have the same average kinetic energy). Ice water has absorbed more heat. Temperature and heat are not the same thing.

[ben from below]

water after it has melted most certainly does not have the same average kinetic energy as ice. That's why it's liqiud. The free water molecules have greater average velocity than the molecules fixed in the ice crystals, hence greater kinetic energy

[Nemesis]

Space is space, dude. Can you tell one piece of air from another?
Air isn't space. Air is matter.

[meshou]

water after it has melted most certainly does not have the same average kinetic energy as ice. That's why it's liqiud. The free water molecules have greater average velocity than the molecules fixed in the ice crystals, hence greater kinetic energyUsing the magic of the internet, I will show you the wonders of Freshman Chemistry. Observe:


When ice melts, it absorbs as much heat energy (the heat of fusion) as it would take to heat an equivalent mass of water by 80 ?C, while its temperature remains a constant 0 ?C.

http://en.wikipedia.org/wiki/Ice

[In...TP]

0C+100: freezing-boiling point
32F+180 = 212: freezing-boiling point

[ben from below]

When ice melts, it absorbs as much heat energy (the heat of fusion) as it would take to heat an equivalent mass of water by 80 ?C, while its temperature remains a constant 0 ?C.


That is correct. Therefore the kinetic energy of the ice has increased by the amount of the heat of fusion.

[meshou]

That is correct. Therefore the kinetic energy of the ice has increased by the amount of the heat of fusion.No. Then the temperature would go up, since the temperature is directly proportional to the average kinetic energy. No temperature increase, no kinetic energy increase.

[ben from below]

where did the energy it abosrbed go then?

[lbloom]

@meshou: Okay, let me get this right: You are proposing that there are patches of space at different temperatures, with heat transfer occurring between them?

(Edit: By "space", I mean featureless areas of vacuum).

[meshou]

(Edit: By "space", I mean featureless areas of vacuum).No. I am working with my understanding that no patch of space ever reaches zero kelvin.

This means either featureless vaccum of space isn't all that common (something I understand to be true), and/ or that where it does exist, there is no temperature to talk about, since there are no atoms for the energy to be transfered to. Notice when I was being more careful, I always said "relitively empty space."

No matter, no heat, no temperature.

[meshou]

where did the energy it abosrbed go then?Into changing from a solid to a liquid.

[lbloom]

This means either featureless vaccum of space isn't all that common (something I understand to be true), and/ or that where it does exist, there is no temperature to talk about

Featureless vacuum does have a temperature to talk about. 'No matter' does not equal 'no temperature'. Radiation transmits through perfect vacuum, and my earlier post was all about how there's a temperature associated with a given frequency of radiation.

[ben from below]

Into changing from a solid to a liquid.

Right. The weaker bond between the water molecules in the ice phase is broken BECAUSE the molecules have more kinetic energy. When you add energy (heat) to the ice, and it melts, the energy doesn't then disappear. The total energy of the ice increases by the heat of fusion, and since there are no other processes, the kinetic energy of the ice, now water, has to increase by EXACTLY that much. Conservation of energy is a quite universal principle

[meshou]

Featureless vacuum does have a temperature to talk about. 'No matter' does not equal 'no temperature'. Radiation transmits through perfect vacuum, and my earlier post was all about how there's a temperature associated with a given frequency of radiation.OK, diagram:

(o)---------m

The intraweb nipple is a star, the dashes are the vaccum of space (no molecules in it), and the m is a random man.

At the nipple-star, there is a lot of heat and it is very hot.

In the featurless vaccum, there is a lot of ENERGY (which is not heat), but since that energy is not transfering or being used for work, there is no heat or temperature.

The man is a crispy critter, as the energy has acted upon his atoms increasing the amount of heat, and so causing them to either rise in temperature or change state.

Yes?

[ben from below]

OK, diagram:

(o)---------m

The intraweb nipple is a star, the dashes are the vaccum of space (no molecules in it), and the m is a random man.

At the nipple-star, there is a lot of heat and it is very hot.

There is lots of ENERGY at the star. The heat is being carried away from the star by its radiation.




In the featurless vaccum, there is a lot of ENERGY (which is not heat), but since that energy is not transfering or being used for work, there is no heat or temperature.

There is temperature. A collection of photons has temperature, even though there is no mass. Its...technical, but since they have energy, there is also temperature.



The man is a crispy critter, as the energy has acted upon his atoms increasing the amount of heat, and so causing them to either rise in temperature or change state.

Yes?
The HEAT has acted upon the man, increasing his ENERGY, and so crispifing him

[lbloom]

Okay, great example to work with. I hope you'll bear with my nit-picking (and try to understand that it's more than that) to reach a happy ending.


At the nipple-star, there is a lot of heat and it is very hot.

Replace "heat" with "energy" and you're golden. It *is* transferring heat into the colder outer space, by radiation alone beyond the point where matter ceases to be.


In the featurless vaccum, there is a lot of ENERGY (which is not heat), but since that energy is not transfering or being used for work, there is no heat or temperature.

There isn't any energy in the vacuum to discuss, save that of the weak radiation passing through. That doesn't really belong to the vacuum, since all the energy entering a given patch is also leaving it. Note that heat is still being transferred through the vacuum, and there's a temperature associated with the frequency of this radiation.

I don't really believe in remembering jargon, so you can call these things the "wrong" names and not get my goat at all - but there's a conceptual distinction between what I'm saying and your understanding.

Hint on the phase change thing: Is temperature during phase change constant irrespective of other conditions?

[lbloom]

@ben: damn, you beat me to it. :)

[meshou]

I don't believe I was technically incorrect, since there is matter in and around a star, and part of how it is raising the temperature is that it is spewing hydrogen into the surrounding space, yes?

Are we forgetting light in addition to the radiation? I know for a fact light passes through a vaccum. However, until light interacts with an atom, I would call it energy, but can you call it heat?

[lbloom]

I don't believe I was technically incorrect, since there is matter in and around a star, and part of how it is raising the temperature is that it is spewing hydrogen into the surrounding space, yes?

If you drew a boundary around the star based on its mass, you could consider the spewed hydrogen to still be part of the star. The space remains as it is. There is no hydrogen travelling through space carrying energy with it. Being matter, it would prefer to stay within the gravitational field of its origin.

Edit: If the momentum of the spewing was sufficient to cause the blob to break free, it would become an independent celestial body, like the star itself.



Are we forgetting light in addition to the radiation? I know for a fact light passes through a vaccum. However, until light interacts with an atom, I would call it energy, but can you call it heat?

Now you're talking! Light is radiation! You understand that last bit you wrote, you should have no issues with extending the concept to heat. "Light" is just that range of frequencies that our retinas are sensitive to. It's all the same.

[ben from below]

I was assuming by radiation, we meant heat. All the electromagnetic radiation emitted by the star should be considered heat.

edit...you beat me this time

edit(part 2). The first sentence should be : I was assuming by radiation, we meant LIGHT.

[meshou]

I was assuming by radiation, we meant heat. All the electromagnetic radiation emitted by the star should be considered heat.

edit...you beat me this timeNo, light (and radiation) is a self propogating partilce/ wave that can change the amount of energy in an atom. It seems to me a method of energy transferance, while heat is the process of it.

[ben from below]

OK. I see what you're saying. Regardless of whether somwthing is absorbing the radiation, the star is still losing energy because it's radiating light, so from the point of view of the star, the light is a type of heat.

[meshou]

OK. I see what you're saying. Regardless of whether somwthing is absorbing the radiation, the star is still losing energy because it's radiating light, so from the point of view of the star, the light is a type of heat.It is neat to see it as a matter of timing. :D

[lbloom]

It seems to me a method of energy transferance, while heat is the process of it.

Radiation heat transfer is a mode of energy transfer in the same way as any other.

[ben from below]

To answer the initial question of the thread, I would say that, intuitively, temperature is a measure of the readiness of a system to exchange energy with another system. There's a technical definition involving entropy that I gave in this thread a few days ago.

[Kljoki]

I think it is good that I have a poor, poor understanding of temperature so you good people can teach me :).
So far I've understood that there are two distinct, related maters relevant here, heat and temperature. My understandings of them are following:

Heat would be total energy released by means of radiation
Temperature would be average kinetic energy of a countable number of something

If these two assumptions are correct, how are heat and temperature linked?


In the featurless vaccum, there is a lot of ENERGY (which is not heat), but since that energy is not transfering or being used for work, there is no heat or temperature.
So energy cannot interact with space as no recipient = no energy transfer. So that would mean that if energy cannot "get into" space, it cannot "get out" of it? Would that mean that for matter, if it cannot interact with space, space has not energy?
From that it seems to me that space would be a medium for spreading of energy as matter.

Also what about interactions between space and other things. Are there situations where space would be capable of energy transfer, where you could "store" energy in space?

And are you saying that something has no temperature if you cannot measure it? What if an object has imaginary temperature, as in a square root of minus one? I'm guessing it would be perceived as nonexistent, immeasurable.


No, it is called "background" radiation because it doesn't originate from matter. The frequency of the radiation (photons) emitted from something is proportional to it's temperature. They say that space (even with no matter in it) emits radiation at a very low frequency. I don't know how they determined this, but that is what they say.I am intrigued by this.
How is this possible? Where does the energy contained in such radiation come from?
Also, how can radiation not originate from matter? If not from matter, from what?