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Less dense implies colder, as the volume is not constant, but expanding. Temperature and density are different things though - one is how much energy something
by count 15y ago
Less dense implies colder, as the volume is not constant, but expanding. Temperature and density are different things though - one is how much energy something has, the other is how far away from other things it is. Related, but different.
With respect to destroying energy - energy converted into matter is 'colder'. There's not the exact same amount of energy - it's not that it can't be destroyed, it must be conserved with matter (E=MC^2). Great example - kinetic energy is used in a particle accelerator to create new particles, and it takes a ton of energy to make even a tiny bit of mass, so the average temperature would go down as more mass is created (heat being the transfer of energy - once it's trapped in a particle, it's not transferred as freely).
(Caveat - I'm not a cosmologist...)
- lionhearted 15y ago> (Caveat - I'm not a cosmologist...) That was really informative, thanks. Man, physics is cool.
- 30thElement 15y agoHow does converting energy into mass make it "colder"? If you have 1 protons worth of energy in a volume, and you have 1 nonmoving proton in another area with the same volume, isn't there the same amount of energy in both regions? Or is it "colder" because you can't have a region with energy and nothing else, it must be something like kinetic energy, which gives heat?
- sp332 15y agoTemperature is the average energy of the particles in a space. So if the proton isn't moving, it is at absolute 0 temperature even though it has some mass-energy left.
- starwed 15y agoHere's a post from cosmologist Sean Carrol: "Energy is not conserved." http://blogs.discovermagazine.com/cosmicvariance/2010/02/22/energy-is-not-conserved/ http://blogs.discovermagazine.com/cosmicvariance/2010/02/22/... tldr: "Energy isn’t conserved; it changes because spacetime does."