The use of a temperature in such a report has two purposes:
- it's expressing something in a way that appears understandable** to most humans, as we feel we know about temperature in a way we don't about kinetic energy;
- it gives a big number, which may not be the case if they were to use joules (and who knows what a joule is?).
** - Okay, all
I know is that a
million degrees is very hot, let alone a figure that's a million times that of the Sun's core (which is itself 15.7 million Kelvins), but it has so little relevance to my day-to-day experience, it's effectively meaningless. But it sounds good.
Well, If you must know... A "Joule", in physics, is a unit of work.
eek
Same thing as a "watt-second". One Joule was originally defined as the amount of work it took to move one Kilogram one meter. That assumed that you had a force trying to prevent you from moving it (like gravity) so the simplest explanation would be the work (mentioned earlier) to
lift one kilogram a distance of one meter (up) on Earth. Now, that doesn't sound like much work, and it isn't. In the other unit system, we all know that one watt isn't very much power. The work done is one watt for one second. That sounds smaller, but it is equivalent to the "Newton-meter".
Now how does this relate to temperature? In Physics, the units of heat are the same as the units of work, also known as Energy. A British Thermal Unit (BTU) is equal to 1055 Joules. So, when Chris says "the few terra-watt hours", we are talking about 7,000,000,000,000 BTU's in one hour, but I suspect Chris is referring to the total power used to get the thing to happen (to get the nuclei of lead near the speed of light right before they smash together.) The energy released would be less because the equipment (the collider) would lose some of that energy in the process.
Probably not much less than half the energy though, and the chambers the collisions occur in are in sizes ranging from 80 cubic meters to a chamber larger than a tennis court with a wall of detectors 3 meters thick. The collisions occur between particles about 100 times smaller than the radius of a human hair, and yet they manage to produce that much energy. What's really incredible is the computing power needed to "catch" a series of collisions for a period of only one second (For example - the muon spectrometer has roughly one million readout channels, and its layers of detectors have a total area of 12,000 square meters. This results in a data output of approximately 300 GigaBytes/second. Giga = 1,000,000,000 )
The energy that is used by the LHC could probably power the entire city of Geneva for several months, but that's a rough guess.
Let's put it this way: I wouldn't want to be inside one of those chambers when the particles collide.