Text 555, 334 rader
Skriven 2004-10-28 06:18:00 av Michael Ragland (1:278/230)
Ärende: Re: Time without end: Phy
=================================



First of all Dr. Barnhill thank you for your thoughtful reply. Please
accept my most profuse apologies should a previous response I made to
you be posted. I informed the moderator of my grievous mistake (which
was caused by just getting up, not having a shower or any coffee so I
was muddleheaded). Hopefully, the moderator will delete it from the
cache. I just demonstrate my own ignorance and nastiness. 

[moderator's note: Of course, I saved a copy. One never knows when
one will need blackmail material, bwah hah hah! - JAH]

Michael Ragland

Michael Ragland wrote: 
Michael Ragland wrote: 
P.S. I thought I was alone in my belief intelligent life could modify
the physical laws of the universe for its own purposes. Many may
strongly disagree with Freeman Dyson but I don't think anybody would
justifiably consider him a crackpot. 

Maurice Barnhill again: 
                Dyson states that he
will discuss what life could do to use or ameliorate the effects of the
expansion of the universe within the known laws of nature. As far as I
can see he does just that. 
        He never uses an equation that is changed from
those we derive from observation. 

Michael Ragland: 
That is correct so I'm mistaken in my statement intelligent life could
modify the physical laws of the universe for its own purposes (at this
time). I equated it with life and intelligence can succeed in molding
this universe of our to their own purposes. Obviously no one in the
physics community would have even mildly entertained Dyson's thesis if
it were not based on human equations derived from observation. And this
should be the case and is. Here lies the strength of Dyson's argument
and alas also where the weakness lies. 

As he states, "Weinberg has here, perhaps unintentionally, identified a
real problem. It is impossible to calculate in detail the long-range
future of the universe without including the effects of life and
intelligence. It is impossible to calculate the capabilities of life and
intelligence without touching, at least peripherally, philosophical
questions. If we are to examine how intelligent life may be able to
guide the physical development of the universe for its own purposes, we
cannot altogether avoid considering what the values and purposes of
intelligent life may be. He states, "I shall make no further apology for
mixing philosophical speculations with mathematical equations." 

Dyson acknowledges, "In conclusion, I would like to emphasize that I
have not given any definitive proof of my statement that communication
of an infinite quantity of information at a finite cost in energy is
possible. To give a definitive proof, I would have to design in detail a
transmitter and a receiver and demonstrate that they can do what I
claim. I have not even tried to design the hardware for my
communications system. All I have done is to show that a system
performing according to my specifications is not in obvious
contradiction with the known laws of physics and information theory." 

He states, "The universe that I have explored in a preliminary way in
these lectures is very different from the universe which Steven Weinberg
had in mind when he said, "The more the universe seems comprehensible,
the more it also seems pointless." I have found a universe growing
without limit in richness and complexity, a universe of life surviving
forever and making itself known to its neighbors across unimaginable
gulfs of space and time. Is Weinberg's universe or mine closer to the
truth? One day, before long, we should know. 

Whether the details of my calculations turn out to be correct or not, I
think I have shown that there are good scientific reasons for taking
seriously the possibility that life and intelligence can succeed in
molding this universe of ours to their own purposes." 

You write, "Dyson states that he will discuss what life could do to use
or ameliorate the effects of the expansion of the universe within the
known laws of nature. As far as I can see he does just that." I could be
wrong (as I obviously was in misinterpreting Dyson) but it is my
understanding recent equations point to an ever expanding universe yet
many physicists believe the universe will ultimately collapse or go into
the "Big Crunch" and that entropy will increase and the arrow of time
will not reverse itself. 

Maurice Barnhill:
If our understanding of the laws is correct, the universe recollapses if
it has enough mass and expands forever otherwise. 
    If there is a so-called cosmological constant or a type of
matter that is functionally equivalent to a cosmological constant the
expansion of the universe can actually accelerate. So our prediction of
whether it is infinite in time depends on measurement of the density of
matter in the universe and the cosmological constant. At the present
time the density of matter appears to be small enough that the universe
should expand forever, and the cosmological constant seems to be nonzero
so the expansion seems to be accelerating. 

Michael Ragland:
If true, how could intelligent life "mould the 
universe to it purposes" without at least supplementing and modifying
our current physical laws or equations based on observation? 

Maurice Barnhill:
If a very powerful civilization found that the universe will collapse,
it might try to move matter around in such a way as to preserve at least
a local region that would not collapse. That effort would not
necessarily involve changing the laws. 

Michael Ragland:
That is interesting. 

Michael Ragland:
Dyson states, "I have found a universe growing without limit in richness
and complexity, a universe of life surviving forever and making itself
known to its neighbors across unimaginable gulfs of space and time. Is
Weinberg's universe or mine closer to the truth? One day, before long,
we should know. 
This "appears" to be reflective of an ever expanding infinite universe.
Dyson states, "These conclusions are valid in an open cosmology. It is
interesting to examine the very different situation that exists in a
closed cosmology. If life tries to survive for an infinite subjective
time in a closed cosmology, speeding up its metabolism as the universe
contracts and the background radiation temperature rises, the relations 
(56) and (59) still hold, but physical time t has only a finite duration
(5). He later states, " I return with a feeling of relief to the wide
open spaces of the open universe. I do not need to emphasize the partial
and preliminary character of the conclusions that I have presented in
this lecture. I have only delineated in the crudest fashion a few of the
physical problems that life must encounter in its effort to survive in a
cold universe. 

So it "appears" he doesn't subscribe to the collapsed universe theory or
closed cosmology. I've been trying to find out on the internet whether
the universe is truly a closed or open system. 

Maurice Barnhill:
I agree, although he seems to consider this as much a hope as a
conviction. 

Michael Ragland:
Perhaps the question 
itself is flawed. My understanding is that Hawking thinks the universe
is a closed system but with no boundaries or edges. I try to
conceptualize that. What does it mean to have no boundaries or edges?
According to entropy or the Second Law of Thermodynamics the universe is
a closed system which must increase in entropy. 

Maurice Barnhill:
In an infinite universe it is problematic to say the least to apply the
Second Law to the universe as a whole. That doesn't prevent applying it
to nearly isolated systems within the universe. 

Michael Ragland:
So you're saying its possible we are part of an isolated system of the
universe where the Second Law of Thermodynamics applies but the law
doesn't necessarily apply to the universe as a whole. If that is the
case what would be the implications for the universe? Would there still
be a partial collapse of the universe in certain areas and in other
areas there would continue to be an expansion?
This would seem to possibly fit the multi-universe bubble space time
model.

Michael Ragland:
Dyson's assumption of infinite life in the universe seems to be based on
an ever expanding and infinite universe. Doesn't this oppose increased
entropy of the universe in the "Big Crunch" assuming that takes place?
If I have misread Dyson again and his philosophical speculations and
mathematical equations suggest the possibility of life in a collapsed
universe then it is very apparent to me one has to have an understanding
of physics equations. 

Maurice Barnhill:
I think that Dyson is avoiding the discussion of any collapsing
universe. 

Michael Ragland:
I think you're right. As you stated his thesis for infinite life seems
to be based on hope as much as conviction and the two are interrelated.

Michael Ragland:
The basis for my statement of modifying the physical laws of the
universe was based on three things primarily, two of which are not
scientific at this time. I suppose that would be an oxymoron. First,
human knowledge of the physical laws of the universe is limited. Second,
given the billions of years the universe will be expanding and the
possibility there is already extremely advanced extraterrestrial life in
the universe it is not farfetched in my view such extraterrestrial life
could advance its understandings of the physical nature of the universe
where it could modify certain aspects of it. 

Maurice Barnhill:
I don't see any sign of this but obviously you can't eliminate the
possibility in principle. I suspect, however, that if this happened the
life would no longer call the changeable part a law and would conclude
that they were mistaken to consider it as law originally. 

Michael Ragland:
I agree.

Michael Ragland:
Third, if the universe is 
entropic and follows the law of the Second Law of Thermodynamics and the
universe ultimately does recollapse certain extraterrestrial life forms
could have the knowledge, science and technology to mitigate against its
effects. 

Maurice Barnhill:
You have an large amount of time to move things around. That might be
enough. You also might fail, and there is no way to tell what would
happen given a much more advanced civilization. 

Michael Ragland:
True! True! This is all philosophical and hypothetical and one could
argue its equivalent to discussing "thin air" but I find it stimulating
nevertheless.

Michael Ragland:
Non of this is obviously scientific and since you are a scientist I
doubt you have much use for it. But I really don't believe in an open
infinite expanding universe with the universe not recollapsing
eventually (if that is what Dyson believes) And many physicists seem to
think intelligent life will be extinguished in such an event. My
argument for infinite life in the universe isn't based on an ever
expanding open universe which gels with our observations or at least
doesn't contradict them as Dyson puts forth. My argument for infinite
life in the universe is based on my belief the universe will ultimately
collapse and increase in entropy and that in the billions and billions
of years before this occurs certain extraterrestrial life forms will
have scientifically and technologically in accordance with their values
and purposes (which may well be continued self survival if the universe
recollapses) to have the theoretical possibility of having much more
physical knowledge of the universe and being able to circumvent the
recollapse of the universe by modifying physical laws of the universe.
Who is to say that right now there isn't some advanced extraterrestrial
life form in the universe who is aware the universe will eventually
recollapse and isn't working on "scientific projects" to contain it,
limit it, mitigate against it, insulate from it, etc. Are we so arrogant
that we can project what extraterrestrial life as well as our own will
be like billions of years from now? 

Anyway, since you are a physicist I have a few questions. You are not
obligated to answer but I am curious. 

(a) What is meant by "multiple universes". "anti universes", etc. Are
they all a part of the same universe and if they are how. If there is a
collapse of the universe will these multiple universes and
anti-universes be equally effected. 

Maurice Barnhill:
I think that there are at least two meanings of multiple universes, and
I don't understand all the possibilities. One, however, is that we are
inside an expanding bubble of space-time which is only part of the
complete universe. There could be other bubbles that we will never be
connected to, and the "constants" of physics might even be different in
the other bubbles. In passing, it is pretty obvious that this idea can
easily fall prey to Occam's Razor. 

Michael Ragland:
That's true but the simplest explanation isn't necessarily the correct
one. I would think multiple universes would add more complexity to the
"universe" and if these other bubbles of space time had possibly
different constants than I wouldn't see that necessarily as merely
multiplicity in terms of number, amount and degree but a multiplicity in
terms of complexity.
I can understand the thinking of (KISS) keep it simple stupid because
there is only so much our brains can absorb in terms of physical
knowledge given their current level of complexity.

Michael Ragland:
(b) If there was a "Big Bang" singularity which created the universe why
couldn't there theoretically be other "Big Bangs' which create other
universes. 

Maurice Barnhill:
There could be. See (a). 

Michael Ragland:
(c) The human mind has a tendency to think of a beginning and an end.
Infinity is a hard concept to grasp but can be demonstrated
theoretically in the sense of numbers 1-infinity. But before the "Big
Bang" which lasted mere seconds there was "nothing"? Even zero stands
for something..a symbol. What existed before the "Big Bang" or the
materials which made up the "Big Bang". Infinity is a hard concept but
"nothing" is even harder. 

Maurice Barnhill:
Time begins with the Big Bang. Therefore there is no before for anything
to exist in. This is a concept to get reconciled to, not to understand
I'm afraid. 

Michael Ragland:
You're right. I don't understand it. This lends itself to metaphysics.

Michael Ragland:
(d) Is it true we don't know what over 90% of the universe is made out
of? 

Maurice Barnhill:
Sure is. There are guesses and speculations but no data, except that
whatever the 90% is participates in gravity but not electromagnetism.
Whether it participates in the weak interactions is not known, and much
of it may have rather strange gravitational effects (accelerating the
expansion of the universe for example). 
 
"It's uncertain whether intelligence has any long term survival value.
Bacteria do quite well without it." 
Stephen Hawking 

Maurice Barnhill:
We are dangerously close to the off-topic line, and I am not sure on
which side. I guess we should think of this as determining the
conditions that extremely persistant life would have to evolve under.
Dyson's article is certainly very interesting in that regard. 

Michael Ragland:
Yes, I agree.
 
Maurice Barnhill
mvb@udel.edu [Use ReplyTo, not From] 
[bellatlantic.net is reserved for spam only] Department of Physics and
Astronomy 
University of Delaware
Newark, DE 19716

"Tiny green men might have been a better experiment."

Stephen Hawking
(paraphrasing from a "Universe in a Nutshell".
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