Claim was made in STRAIGHT DOPE CLASSIC - 03/30/1984, from the Nov 30 email.
Untrue.
Light may be regarded as having a temperature, as can black holes.
Source: myself (PhD in theoretical physics, 1990)
Claim was made in STRAIGHT DOPE CLASSIC - 03/30/1984, from the Nov 30 email.
Untrue.
Light may be regarded as having a temperature, as can black holes.
Source: myself (PhD in theoretical physics, 1990)
What is the temperature of light then? Is it at all dependent on the medium (or lack of) that light is passing through? Does your argument depend on light being a particle or a wave? Or both?
How can a black hole have a temperature? How could we mesure such a thing when nothing can escape?
Without a particle’s energy to measure, how can we find that nothing has a temerature?
I always wondered what physicists do in their spare time. Do you swing bowling balls around on piano wire and stuff?
Just kidding–you’re going to be an extremely welcome presence on the boards, Dr. pjcamp!
Another randome thought: does anybody else thing that the guy’s nose in the accompanying illustration look extremely, um, phallic?
The concept of “monkey-loving” may be regarded as having a temperature.
Source: Me (BA Chemistry 2002).
You see why we need more info?
The temperature of an Adirondack lake during any time of year, even high summer, can be considered to be below absolute zero.
I’ll try this one…
One way temperature can be defined in terms of entropy. And a black hole does have a definite entropy – which happens to be directly related to its radius, believe it or not. And its radius depends upon its mass. Another way to define temperature is in terms of the temperature of the black-body radiation emitted by the black hole – which per Hawking also depends upon its mass.
For a black hole with mass m, the temperature is T = (hbarC^3)/(8pi*G k m).
So a black hole indeed has a temperature (its “Hawking temperature”), which depends on its mass.
Source: start with http://www.hawking.org.uk/lectures/entropy.html (Stephen Hawking, PhD Physics 1965, Cambridge)
-mok
Thanks for the cite Mok. At least somebody knows how to make an intelligent post.
A previous thread on what it means for light to have a temperature. Granted, my explanation therein uses the idea of the light interacting with particles, but that’s only because I was trying to explain the concept by relating it to a more commonly understood notion of temperature. The radiation has a temperature, regardless of whether there are particles there or not.
It might be worth noting that there’s nothing particularly quantum mechanical about light having a temperature and the concept was introduced in 19th century classical physics. Though it was just such questions that led to Planck’s Law and quantum physics.
As for the OP, I agree that the statement is a bit sloppy. But note that there are comments further on, about the CMBR, where Cecil implicitly acknowledges that space with radiation in it has a non-zero temperature.