In Stephen Baxters book ''Time'' we find ourselves in
world where it becomes possible to detect messages traveling back
through time. Thereby making it possible to learn from distant
descendants how to transform the structure of our current space-time,
into structures even better suited for mind and intelligence.

--

Indeed, what is time, but something that can create minds?
And something minds use to make sense of the world?
? It seems to be an undercurrent in some of Baxters books,
and btw. also very much present when you read physicist Carlo Rovellis
books?

Still, setting your head around >>time<< is not easy though.
And too often, when an idea about >>time<< has been
presented, there is something not quite right,
something missing.
Are time making minds, or are minds making time, or?

Picking up physicist Carlo Rovelli's book ''The Order of Time''
helps create some order though...
Baxter was on to something in ''Time'':
The concept of time and is connected to the concept of minds.

Rovelli describes an experience he had as a student when taking LSD:
>>Among the strange phenomena was the sense of time stopping.
>>Things were happening in my mind but the clock was not going ahead;
>>the flow of time was not passing any more.
>>It was a total subversion of the structure of reality.
https://www.theguardian.com/books/2018/apr/14/carlo-rovelli-exploding-commonsense-notions-order-of-time-interview

Time is apparently something that is happening in our minds?

In ''The Order of Time'', Rovelli continues (In the section ''crumbling
of time''):
''If I were to ask: Are these two stones at the same height? In
interplanetary space, the correct answer would be, that the question
doesn't make any sense...
because there is no single notion of same height, throughout the
Universe. Similarly, if you ask whether two events are happening at the
same moment, the correct answer is that it doesn't make sense, because
there is no such thing as same moment throughout the Universe''...

In special relativity, we have that two events occurring far apart,
might even happen in one order when viewed by one observer, and in the
opposite order when viewed by another.

In the section of Rovelli's book called ''The World without Time'',
Rovelli describes physicist John Wheelers reaction to one of his own
equations in quantum gravity, where there was no time variable:
''Explain time? Not without explaining existence!
Explain existence? Not without explaining time!
To uncover the deep and hidden connection between
time and existence... is a task for the future...''

Sure... :)

Still, according to Rovelli, ''There is nothing mysterious about the
absence of of time in the fundamental equations of quantum gravity...
Such theories describe how things change,
one in respect to the others, how things happen in the world in relation
to each other...''
>>The movement of bodies is described in relation to other bodies.
>>Time holds no priviledged position. Change is more important.

According to Rovelli time comes because we can't see these many details.
''The physical interactions between the part of the world to which we
belong, and the rest are blind to many variables...''

>>It is not possible for us to register all the quantum fluctuations
>>going on at any one moment,
>>so our interaction with the world becomes partial; we see a blurred
>>version of it.
>>We take things that emerge at scale and think of them in terms of
concepts that are meaningful.
>>So in a world without time, we seem to create it
>>– and that process is highly personal.

According to Rovelli, ''this opens up the possibility that it wasn't the
Universe that was in particular configuration in the past...
Perhaps it is us, and our interactions with the universe that are
particular.
We are the ones who determine a particular macroscopic description?
The initial low entropy of the Universe, and hence the arrow of time
(springing from this), may be more down to us, than to the Universe?
....
If a subset of the Universe is special in this sense, then for this
subset the entropy of of the Universe is low in the past, the second law
of thermodynamics obtains, memories exists, traces are left - and there
can be life and thought''.

Indeed, ''What makes the world go around is not energy, but low entropy.
Where we belong to a part of the world where spacetime has a dimension
called time, and where entropy grows...''

Inside our heads this then becomes a new approximation,
an approximation on an approximation, where time is uniform,
universal and ordered.

According to Andrew Jaffe:
''Rovelli reconstructs how our illusions have arisen, from aspects of
thermodynamics and quantum mechanics.
He argues that our perception of time's flow depends entirely on our
inability to see the world in all its detail''.
https://www.nature.com/articles/d41586-018-04558-7

Time itself disappears at the most fundamental level.
But the world we see is a world through a filter.
We observe a Universe that is becoming increasingly disordered.
Where Rovelli tell us, that out experience of time comes from (this)
entropy, and the second law of thermodynamics?
Filtered by our position in our corner of the Universe, and our perceptions.
Other portions (parts) of the Universe might have given us a different
perspective of what time really is.

Indeed, again we are back to the relationship between Time and Minds.
Time creates minds, or is minds that create time,
in order to create more minds,
as Baxter said all along...