Absolute High Temperature

[Martin]

I have read that the temperature at the "big bang" was nearly infinite.

 

1.4 x 10³² kelvin (the planck temperature) is nearly infinite

by any reasonable human reckoning

 

in technical articles that's apt to be equated with BB temp.

I've never seen any scientific artlcle that suggested it was higher than that.

estimated density at BB time is also about planck unit density (if you are interested)

[Martin]

Some scientists seem to have evidence that there are particles escaping from black holes' date=' implying that they travel faster than the speed of light.

 

Does this mean that time goes backwards (reverses) ?[/quote']

 

I believe you are talking about hawking radiation, which black holes theoretically give off

(never observed, but let's give it the benefit of the doubt)

 

the particles in hawking radiation do not go faster than light

and they do not escape from inside the event horizon

they escape from right outside the border, just barely outside the event horizon. so they dont break any rules of theory.

 

speaking locally (not about distant galaxies receding because of the expansion of space, but about things you could in principle see up close)

nothing you could call a particle would ever travel faster than light----

or at least this is the consensus view and no experimental observation has sofar contradicted it.

 

distant galaxies recede from us faster than c, but that is a different story

[Douglas]

I believe you are talking about hawking radiation' date=' which black holes theoretically give off

(never observed, but let's give it the benefit of the doubt)

 

the particles in hawking radiation do not go faster than light

and they do not escape from inside the event horizon

they escape from right outside the border, just barely outside the event horizon. so they dont break any rules of theory.

 

speaking locally (not about distant galaxies receding because of the expansion of space, but about things you could in principle see up close)

nothing you could call a particle would ever travel faster than light----

or at least this is the consensus view and no experimental observation has sofar contradicted it.

 

distant galaxies recede from us faster than c, but that is a different story[/quote']

If light can only reach the event horizon, and the Hawking radiation is barely outside the event horizon, why arn't they travelling faster ?

[jordan]

Hey Martin, what exactly is "planck temperature"?

[Martin]

Hey Martin, what exactly is "planck temperature"?

 

hi jordan, really glad you asked! one answer is just go to the NIST

"fundamental physics constants" site and look it up. It gives both the value in kelvin and the formula in terms of planck's constant and the speed of light.

 

then you can ask any theoretical physicist to give his or her interpretation of the "significance" of it, or the significance of the planck scale in general

 

but a good way to start is just get the value and formula, it is just a temperature that Max Planck first calculated in 1899 as "Natural Unit"

(he calculated natural units of mass, length, time, temperature in a paper on thermodynamics and radiation that he presented that year)

 

and the usual formula (in modern notation) is

 

[math]T_{Planck} = \frac{1}{k}\sqrt{\frac{\hbar c^5}{G}}[/math]

 

(there are better more intuitive approaches to it but that is what you'll see at the NIST website or most any textbook that has it)

 

and it is an absurdly hot temp of 1.4 x 10^32 kelvin.

 

Here is the link

http://physics.nist.gov/cuu/Constants/

you go "universal constants" and then you see Planck temperature on the menu, and you get the formula by clicking on the symbol T-sub-P

 

in the formula k is the Boltzmann constant that you see in so many formulas in first year College Physics, thermodynamics, kinetics, speed of sound, temperature/pressure law, Gas Law, you are always seeing things like E =kT where k is the Boltzmann. It associates a characteristic bit of energy to each temperature

[Martin]

Hey Martin, what exactly is "planck temperature"?

 

associated with any temp T there is a typical energy kT which is characteristic of photons of light at that temp and also of particles moving at that temp---it is not exactly the most probable or the aveage but it is a key energy characteristic of that temp.

 

A way to think of Planck temp is this way: It is the temperature at which photons typically have the Planck length as their wavelength and the Planck energy as their energy.

 

Also at that temperature, any particles like quarks which might exist have the Planck energy as a typical energy

 

If you know SI metric units then you know joule (raise a kilogram 10 centimeters) and you know Gigajoule. the planck energy is about 2 GJ.

this is roughly the fuel energy contained in a car's tankful of gasoline. It is a hell of a lot of energy.

In a box which is at Planck temperature, the photons inside the box will be monsters each photon carrying as much energy as in a tank of petrol.

One photon if it hits you delivers as much energy as burning a tankful of petrol. these are extreme conditions

 

but that is all OK and proper because they are big bang conditions, so they should be extreme

[brad89]

Absolute zero has been deifined.

 

 

Is there an established "Absolute Highest Temperature" in the universe?

 

I imagine this was at the Big Bang' date=' but is there a constant limit to matter and energy now?

 

[/quote']

 

That makes a lot of sense, because all of the energy currently existant was packed within one atom that was even smaller than a current atom. So, I guess the absolute highest temp. would have to be the point where all of the energy in the universe is concentrated into one point. This would be the maximum existant temperature, but the question is more of "can the energy of an object be maxed out so that it can't be filled anymore?" Some type of limit, and absolute heat?