Do you think there's an upper limit on temperature?

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darkxshade

Lifer
Mar 31, 2001
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Originally posted by: DrPizza
It's probably worth pointing out that the temperature of the surface of the sun is about 6000 degrees C; it's relatively cool compared to the rest of the sun - both the core, and the corona. Intuitively, people think that the surface of the sun is the hottest part of the sun. I don't know why, but it isn't. The core of the sun is 15.7 MILLION degrees C. The temperature of the corona is about 5 MILLION degrees C. So, 6000 degrees C at the surface is pretty cold; relatively speaking. Nonetheless, temperature is a somewhat meaningless statistic; or at least, misunderstood. For example, the thermosphere around the earth reaches temperatures of 1000 degrees C. But, because the air is so thin there, that really doesn't represent a lot of energy.

in my OP post, I only mentioned the surface because even if we were able to reach temps at the surface of the sun, it would be too hot that any experiment to test the upper limit would fail horribly.
 

darkxshade

Lifer
Mar 31, 2001
13,749
6
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Originally posted by: Eli
Originally posted by: BoomerD
IIRC, our sun is actually a fairly cool star. There are some stars which burn at a MUCH hotter temp than ours does.
Very much hotter. :Q

Hottest star's surface temperature = ~220,000ºK.

Our sun's surface temperature = 5780ºK.

Frigid in comparison..

what's our suns core temp? would be an interesting comparison to the surface of the hottest star
 

slugg

Diamond Member
Feb 17, 2002
4,723
80
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Originally posted by: finite automaton
Absolute zero means an object has no heat energy.

The opposite would mean that an object had an infinite amount of heat energy (obviously, not possible)

Edited for clarity.

This is exactly correct.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,419
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81
Originally posted by: darkxshade
Originally posted by: Eli
Originally posted by: BoomerD
IIRC, our sun is actually a fairly cool star. There are some stars which burn at a MUCH hotter temp than ours does.
Very much hotter. :Q

Hottest star's surface temperature = ~220,000ºK.

Our sun's surface temperature = 5780ºK.

Frigid in comparison..

what's our suns core temp? would be an interesting comparison to the surface of the hottest star
Roughly 16,000,000ºK as DrPizza says.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,419
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In fact, even during its life in the main sequence, the Sun is gradually becoming more luminous, and its surface temperature is slowly rising. The increase in solar temperatures is such that in about a billion years, the surface of the Earth will become too hot for liquid water to exist, ending all life.[30][31]
Well, geez. That's depressing. Thanks for ruining my day, Wiki.

:p
 

dullard

Elite Member
May 21, 2001
26,063
4,710
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Note: I have to assume you mean the American short version of trillion (10^12), and not the international long version (10^18). If you meant the long version, I am sorry, but you'll have to correct the math yourself.

The posters are on the right lines. Good and short article. I'll summarize it even further:

Temperature is related to the motion of the particles. The motion (speed) of the particles depends on their energy and their mass. If you could take the lightest possible particle and gave all the energy you could possibly give it, then its speed will approach the speed of light.

The planck's temperature is a reasonable approximation of that maximum temperature. At the planck's temperature, we can no longer see additional temperature increases, thus why bother considering higher temperatures? The temperature could exceed the Planck's temperature, but we'd never know it (the particle becomes a black hole).

Planck's temperature is 1.4*10^32 K.




The radiation heat question is even more complicated. Lets consider the case just before it is a black hole.

We need to know the black body properties of that particle (emissivity). That is, does the surface transmit all of the energy or does it absorb some of it? Assuming it is a perfect black body, then the energy it radiates per unit area is:

q/A = 5.67*10^-8 W/m^2K^4 * T^4 where T is the planck's temperature.

Thus, the body radiates 2*10^121 W/m^2 of energy. It would be really hard to maintain the temperature with this amount of energy radiating out of the body, but lets pretend we can do so.

Now, we just need to know the surface area of this black hole. The radius of a black hole is 2*G*M/c^2. Where G=6.67*10^-11 m^3/kg/s^2 and c is the speed of light. M is the mass of the particle, which unfortunately we do not know since mass increases with velocity. Rather than calculate it, I'll just assume the radius is 10^-15 meter. Someone else can come in and calculate that for me.

Thus, if the black hole is 10^-15 m in radius, the amount of heat it radiates is 2.7*10^92 W. At a trillion light years away, we would only receive a small fraction of that radiated energy. In fact, an adult human has only of 1 m^2 area (only half of the adult is facing this particle) and the heat radiating from the particle is passing through an area of 1*10^57 m^2 a trillion lightyears away. Thus, we only receive 1 W out of every 10^57 W radiated from the particle. Or, we'd each recieve 2.4*10^35 W of energy.

Since the sun gives the entire Earth 3.2 *10^13 W of energy, I'd say we'd be toast.

Note 2: Someone had better doublecheck my math.
 

yankeesfan

Diamond Member
Aug 6, 2004
5,922
1
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Originally posted by: Eli
Originally posted by: Psynaut
Isn't temperature determined by the movement of molecules? Absolute freezing would be when the molecules stop moving altogether. So conversely, if the speed of light is the fastest anytthing can move (which I guess is questionable) then the hotest anything could get would be the temperature achieved when the molecules move at the speed of light.

Admitedly, I am not a scientist and this is pure conjecture. I'm just trying to apply logic to a question I don't really know anything about.
Heat is energy.

When something becomes hot, its molecules have a lot of thermal energy. Keep adding energy and solids melt and liquids vaporize as their thermal energy exceeds the forces that bind their atoms together.

Add more energy and atoms become electrons and plasma. Add more energy, and the temperature will continue to rise.

Since there is a limit to the total amount of energy in the universe, there is a limit to how hot something could become.

They estimate that the temperature of the newborn universe was 10^32 K. That's hot.

Obviously we could never harness all the energy in the universe, so it is not possible to reach the highest possible temperature.
Fixed?
 

spidey07

No Lifer
Aug 4, 2000
65,469
5
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I "think" that at the actual big bang temperature was indeed infinite?

I'm not talking after it, the actual bang itself.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,419
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Originally posted by: dullard
<snip>
Note 2: Someone had better doublecheck my math.
What he said.

And um, looks good to me. ;) lol

 

DrPizza

Administrator Elite Member Goat Whisperer
Mar 5, 2001
49,601
167
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www.slatebrookfarm.com
Originally posted by: darkxshade
Originally posted by: DrPizza
It's probably worth pointing out that the temperature of the surface of the sun is about 6000 degrees C; it's relatively cool compared to the rest of the sun - both the core, and the corona. Intuitively, people think that the surface of the sun is the hottest part of the sun. I don't know why, but it isn't. The core of the sun is 15.7 MILLION degrees C. The temperature of the corona is about 5 MILLION degrees C. So, 6000 degrees C at the surface is pretty cold; relatively speaking. Nonetheless, temperature is a somewhat meaningless statistic; or at least, misunderstood. For example, the thermosphere around the earth reaches temperatures of 1000 degrees C. But, because the air is so thin there, that really doesn't represent a lot of energy.

in my OP post, I only mentioned the surface because even if we were able to reach temps at the surface of the sun, it would be too hot that any experiment to test the upper limit would fail horribly.

Wrong. Horribly wrong. Counter-example: The Tokomat Fustion Test Reactor (at Princeton) set a world record for temperature:
510 MILLION DEGREES C (fwiw, a temperatures like that, it makes no difference in using K or degrees C, since they always differ by a constant amount = to the the temperature (in degrees C) of absolute zero)

So, your 6000 degree C temperature (a little less actually) at the surface of the sun is pretty pathetic compared to the TFTR. Even the coronal or core temperatures of the sun are puny in comparison.

edit: oh, link
 

Train

Lifer
Jun 22, 2000
13,587
82
91
www.bing.com
Originally posted by: Psynaut
Isn't temperature determined by the movement of molecules? Absolute freezing would be when the molecules stop moving altogether. So conversely, if the speed of light is the fastest anytthing can move (which I guess is questionable) then the hotest anything could get would be the temperature achieved when the molecules move at the speed of light.

Admitedly, I am not a scientist and this is pure conjecture. I'm just trying to apply logic to a question I don't really know anything about.

Lets assume the speed of light is the upper limit of how fast a molecule can move.

Is there a function that can translate vibration speed of a molecule directly to a temperature? If so cant we compute what temperature molecules moving at the speed of light would be?

I have a feeling this might be different for each element.

 

darkxshade

Lifer
Mar 31, 2001
13,749
6
81
Originally posted by: DrPizza
Originally posted by: darkxshade
Originally posted by: DrPizza
It's probably worth pointing out that the temperature of the surface of the sun is about 6000 degrees C; it's relatively cool compared to the rest of the sun - both the core, and the corona. Intuitively, people think that the surface of the sun is the hottest part of the sun. I don't know why, but it isn't. The core of the sun is 15.7 MILLION degrees C. The temperature of the corona is about 5 MILLION degrees C. So, 6000 degrees C at the surface is pretty cold; relatively speaking. Nonetheless, temperature is a somewhat meaningless statistic; or at least, misunderstood. For example, the thermosphere around the earth reaches temperatures of 1000 degrees C. But, because the air is so thin there, that really doesn't represent a lot of energy.

in my OP post, I only mentioned the surface because even if we were able to reach temps at the surface of the sun, it would be too hot that any experiment to test the upper limit would fail horribly.

Wrong. Horribly wrong. Counter-example: The Tokomat Fustion Test Reactor (at Princeton) set a world record for temperature:
510 MILLION DEGREES C (fwiw, a temperatures like that, it makes no difference in using K or degrees C, since they always differ by a constant amount = to the the temperature (in degrees C) of absolute zero)

So, your 6000 degree C temperature (a little less actually) at the surface of the sun is pretty pathetic compared to the TFTR. Even the coronal or core temperatures of the sun are puny in comparison.

edit: oh, link

interesting... I'll admit, I know nothing about all of this but what was stopping whatever was generating this amount of heat from melting through and killing everything?

 

darkxshade

Lifer
Mar 31, 2001
13,749
6
81
Originally posted by: DrPizza
Incidentally, since no one's directly answered it (although temperature of the universe at the big bang is the answer), here's your answer.

actually dullard mentioned the Planck temperature but I'll def check this out, thanks
 

spidey07

No Lifer
Aug 4, 2000
65,469
5
76
Originally posted by: DrPizza
Incidentally, since no one's directly answered it (although temperature of the universe at the big bang is the answer), here's your answer.

But that didn't come about until AFTER the big bang. The actual big bang was hotter, infinity. Plank temperature is related to plank time which is AFTER the big bang.

What I'm trying to say is you can go hotter than plank temp.
 

MrPickins

Diamond Member
May 24, 2003
9,125
792
126
Originally posted by: yankeesfan
Originally posted by: Eli
Originally posted by: Psynaut
Isn't temperature determined by the movement of molecules? Absolute freezing would be when the molecules stop moving altogether. So conversely, if the speed of light is the fastest anytthing can move (which I guess is questionable) then the hotest anything could get would be the temperature achieved when the molecules move at the speed of light.

Admitedly, I am not a scientist and this is pure conjecture. I'm just trying to apply logic to a question I don't really know anything about.
Heat is energy.

When something becomes hot, its molecules have a lot of thermal energy. Keep adding energy and solids melt and liquids vaporize as their thermal energy exceeds the forces that bind their atoms together.

Add more energy and atoms become electrons and plasma. Add more energy, and the temperature will continue to rise.

Since there is a limit to the total amount of energy in the universe, there is a limit to how hot something could become.

They estimate that the temperature of the newborn universe was 10^32 K. That's hot.

Obviously we could never harness all the energy in the universe, so it is not possible to reach the highest possible temperature.
Fixed?

I was wondering that myself...

Also, I'm pretty sure it's not "degrees Kelvin", just "Kelvin."
 

dullard

Elite Member
May 21, 2001
26,063
4,710
126
Originally posted by: MrPickins
Also, I'm pretty sure it's not "degrees Kelvin", just "Kelvin."
It wasn't that long ago that it was "°K". I don't know why, but they moved the kelvin (lowercase is proper in this context) scale to just "K". I think the problems from the change outweigh the minimal gains.

 

Rubycon

Madame President
Aug 10, 2005
17,768
485
126
Originally posted by: spidey07

What I'm trying to say is you can go hotter than plank temp.

Happens everytime someone walks the plank. :laugh: