A good exposition. It doesn't address the questions of the alignment of thermodynamic,
radiation, and spacetime expansion though. This paper may be of interest:
Arrows of Time in the Bouncing Universes of the No-boundary Quantum State
James Hartle <http://arxiv.org/find/hep-th/1/au:+Hartle_J/0/1/0/all/0/1>,Thomas Hertog
(Submitted on 9 Apr 2011 (v1 <http://arxiv.org/abs/1104.1733v1>), last revised 16 Apr 2012
(this version, v3))
We derive the arrows of time of our universe that follow from the
of its quantum state (NBWF) in a minisuperspace model. Arrows of time are
four-dimensionally as properties of the four-dimensional Lorentzian
histories of the
universe. Probabilities for these histories are predicted by the NBWF. For
with a regular `bounce' at a minimum radius we find that fluctuations are
small at the
bounce and grow in the direction of expansion on either side. For
classical histories with big bang and big crunch singularities we find that
fluctuations are small near one singularity and grow through the expansion
recontraction to the other singularity. The arrow of time defined by the
fluctuations thus points in one direction over the whole of a recollapsing
but is bidirectional in a bouncing spacetime. We argue that the
thermodynamic, and psychological arrows of time are aligned with the
arrow. The implications of a bidirectional arrow of time for causality are
On 12/4/2013 3:37 AM, Alberto G. Corona wrote:
Yes there is no loss of information/at the lowest level,/ that is at the quantum level .
But at the lowest level, there is NO notion of HEAT. only speeds and momentums of
elementary particles. HEAT and temperature and entropy are statistical parameters,
words used in the macroscopical laws to define sum of energies and mean energies or
disorder of particles because the energy of each particle is not know at the human scale
but each particle carry all the information intact.
THe post is talking about the loss of information contained in a macrostate consisting
of a phisical bit of information stored in a macroscopical object. For example a gate.
The conservation of information on the laws of physics refers to the information of the
microstates. not macrostates, whose information can be lost. and loss of information in
a macrostate generate increase of entropy by the following reason:
in terms of state, an increase of entropy is produced when we pass from a macrostate
with less possible microstates to other with more possible microstates. At the
beginning we have one macrostate , for example 1 formed by all the possible
configurations of electrons in a gate when it stores a 1. when erased, we have a
macrostate that may be one of the possible configurations of electrons that may be in a
gate with a 1 OR a 0 or a neutral state. So the entropy has increased because the new
macrostate (erased) has more microstates than the original. the disorder has increased.
How that entropy increase is produced in the erase depend on the process. It may be by
means of a short circuit in the gate. The electrons circulate and hit the atoms
producing heat. the potential electric energy of attraction produces cynetic energy in
the atoms and heat.
The microstate-macrostate transition is the same case that happens when we have a gas of
different types confined in a room and other room empty. When we communicate the rooms,
the gas expand and fill both rooms, the entropy increased because the final macrostate
admits more possible configurations speeds and positions of particles in the two rooms
. Something similar, not equal, happens with gas of electrons in a gate. Measured in
termodinamical terms, the temperature decreased and the entropy measured in
termodinamical terms delta Q/T has increased. Q is the thermal energy or heat.
However the process is different. in the first case, potential energy is dissipated and
there is increase of Q, in the other the potential energy is dissipated against the
vacuum and produces reduction of T. Q/T seems to be proportional to the number of
microstates in a macrostate.
The availability of information in the form of macrostates when entropy is low is what
permits living beings to compute in order to anticipate the future and survive. That can
only happen in the direction of entropy increase. I wrote something all of this here:
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