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[OngBonga]

That stuff about quark tension is cool.

Light always travels at c

So we're back to the problem of the entire life of the EW universe happening before light can travel even a tiny distance. That really does bend my head. Certainly, I feel like our concept of time is redundant in this world. I mean, the best I can imagine is that the universe is so dense, that even though a photon only travels a tiny distance in during the entire EW epoch, it still interacts with a truly massive amount of energy. I keep thinking of particles colliding, but I know we're at a much more quantum level than that. Still, it's a reasonable metaphor for what I can't understand going on, so forgive me if I persist with it. When we talk of time, we have to think of space, too. I think a light cone (actually a sphere) one light second in diameter would be a fair spacial representation of a second in time. This is the range of causality. A light cone with a diameter of 10^-43 light seconds is practically a singularity, yet an enormous amount of stuff must be happening in this region. From a tiny universe in a fraction of a second came the hugest and most complex of systems. It really does make you wonder what the fuck time really is.

Time doesn't flow backwards, as far as we can observe. It flows at different rates for different observers, but always in the same direction. That reminds me of the second law of thermodynamics. Is time just the flow of entropy? Nature's eternal quest for equlibrium?

[MadMojoMonkey]

Time doesn't flow backwards, as far as we can observe. It flows at different rates for different observers, but always in the same direction. That reminds me of the second law of thermodynamics. Is time just the flow of entropy? Nature's eternal quest for equlibrium?

The "thermodynamic arrow of time" is directly related to the 2nd Law of Thermo.

[OngBonga]

The "thermodynamic arrow of time" is directly related to the 2nd Law of Thermo.

Something I was watching about entropy yesterday seemed to suggest that it's the result of probability. This confused me, because they kept saying heat NEVER spontaneously moves from cold region to warm. Surely if probability governs this, then we should expet to see it happen rarely?

[MadMojoMonkey]

Something I was watching about entropy yesterday seemed to suggest that it's the result of probability. This confused me, because they kept saying heat NEVER spontaneously moves from cold region to warm. Surely if probability governs this, then we should expet to see it happen rarely?

Thermodynamics describes systems with large numbers (greater than Avogadro's number) of particles.
The statements of thermodynamics came about to explain and understand experimental results prior to the quantum description of nature.
The statistical statement that heat never flows spontaneously from cold to hot is experimentally verified for systems of particles.
Statistically speaking, the "never" is an overstatement, but not a terrible one. The equipartition theorem states, broadly, that systems of particles tend toward thermal equilibrium, and not toward isolated regions of high and low temperatures. "Tend toward" is a statistical statement, and we generally look at the large ensemble of particles as a dynamic equilibrium.

A moving pendulum is in dynamic equilibrium. At any given time, it's total energy is constant, but whether that energy is kinetic or potential varies.
This is similar for temperature. At any given time, the individual atoms of a molecule can have dramatically different thermal energy, but the overall energy of the molecule remains relatively constant and in thermal equilibrium with its environment.


However, Quantum Mechanically, there is no such thing as entropy. All QM processes are time-reversible. I.e. any process that is observed to happen forward in time is also observed to happen in another experiment, but in the opposite order, and with particles and anti-particles swapped.

So entropy is a breaking of symmetry at some scale of particle interactions?