Re: A thought experiment...

On Mar 1, 4:37 am, Jonathan Thiessen
<jjthies...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
PD wrote:
On Feb 27, 12:30 am, Jonathan Thiessen
<jjthies...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
PD wrote:
On Feb 25, 4:09 pm, Jonathan Thiessen
<jjthies...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Salutations,
I was thinking awhile back [as is customary], and I came up with a bit
of a thought experiment. I'm not interested in getting into debates,
and/or flame wars. Physics is my favourite science for the fact that it
has the greatest tendency of the physical sciences to be [surprise :P]
scientific [this is, methodical, and open/objective]. Mathematics is
completely objective, however, in and of itself, I wouldn't really
consider mathematics to be physical/tangible. But anyway... enough for
precursory ramblings. If you find anything straight-up wrong, or
otherwise questionable [that is phrased as being absolute], please bring
it up so that it may be reconciled [ie so that I can fix it [including
my understanding]].
----
Definitions:
D.1: Let the Universe be defined as being everything physical in
existence [ie all matter, and energy]
Assumptions:
A.1: Assume that the Universe has always existed [ie an
indefinite/infinite amount of time has already lapsed]
A.2: Assume that The Fundamental Laws of Thermodynamics are indeed correct
Implications:
I.1: By The First Law of Thermodynamics [A.2], there is nothing that is
being created, nor destroyed
Comments:
D.1 is inconsistent with the definition of Universe as physicists
presently understand it.
I see. I was defining the universe of discourse, or sample space. My
intention was to include... well... everything really. I must say, I'm
not really up on my physics jargon, I suppose [or modern physics, for
that matter]. What precise meaning would a physicist give to the word
"Universe"? Any also, what did I fail to include in my definition that
would have significance in this problem?

Yes, you see, the problem is *defining* to be the universe to be
everything conceivable or everything possible by definition. There are
actually several connected variants of definitions for physical
universe that are actually useful and meaningful. One is "observable
universe", which means those things that we could, in priniciple if
not in practice, detect. Another is "that which is causally related to
our observable universe", which broadens the scope to include what was
included in the big bang, though the subsequent expansion of spacetime
may have rendered some portions of that universe to be unobservable
from here, even in principle. Another softer definition is, the domain
over which the laws of physics as we understand them apply.

The distinction is illuminated by the idea of a "multiverse", which
contains several domains, each with their own different sets of
physical laws and each with their own observable subsets, and each
with their own dimensionality and possibly some meaningful beginning
and end --- our universe being one of these domains. The problem is
that it is impossible, even in principle, to acquire any information
from any other universe in the multiverse, though it is of course
possible to conceive of what some of them might be like. Since we
cannot get any observational evidence of any of these other universes,
any speculations about them are not scientifically testable; and so
lie outside the domain of science.

In a very real way, we cannot meaningfully *define* a universe to be
everything that exists, because some portion of what may exist will
forever be undetectable by us. And since we cannot then distinguish
"may exist" from "does exist" or "does not exist", it becomes
scientifically useless.

Stating that something is unobservable in theory, is equivalent to
stating that there exists no possible means of interaction with it. This
is equivalent to saying that it is closed wrt us/our existence. If
something is closed wrt us, would that not make it irrelevant? The
concept of a multiverse is a very nice mental exercise, but if we're
completely isolated from all other elements of this multiverse, for all
practical intents, and purposes, it/they don't exist.


Quite so, and this is a problem with multiverse "theories" in that
they are inherently untestable. If you read Dr. Randall's book,
though, it may be possible that gravitation is the one exception that
could traverse from one universe to the other, and if so, then this
connection might be testable. We'll see.

However, there is a converse problem. If you say that the other
universes for all practical purposes don't exist (because we can't
sense them), then the temptation for our sole remaining universe is to
say that the laws of physics as they are exhibited here *have* to be
the way they are, and that there is some fundamental reason that they
are this way and no other way. Well, that would be a mistake too,
wouldn't it?

I'll give you a loose analogy. Suppose we defined language as being
evidenced by effective communication. Well, if we went to another land
and encountered noises coming from other people's mouths, one *might*
conclude that it isn't a language at all, because the visitor is
unable to effectively communicate with it. Of course, this doesn't
happen in real life, because there is evidence that those people are
communicating with each other (if not with the visitor) and there are
some people who demonstrate that they can use both languages and so
forth. However, we are less likely to admit that there is a language
between, say, trees or bacteria -- simply because there is a stronger
barrier for seeing evidence that there really is effective
communication going on there. It would be a mistake, though, to
presume that their language simply does not exist and that there is
something unique about humans and language. Do you see my point?


A.1 is inconsistent with observation
This is the point of proof by contradiction. In fact, this was really
the point that I was trying to substantiate some sort of proof. If the
universe is finite in nature, how did it come into existence?
Admittedly, I am relatively ignorant of the finer points [and quite
possibly even general notions] of the Big Bang/singularity
theory/theories. Is the "not quite so big before the Bang" singularity
supposed to be it's own pre-existing entity? What caused it to become
unstable? If it was an internal disruption, then it obviously wasn't at
any sort of a equilibrium deadlock [in which case, wouldn't it also have
to have existed for a finite period as we already agreed that it did? In
which case, where did it come from].

A couple of comments
- Science doesn't get very far with proof. Physicis is not based on
axiomatic logic. It is based on *induction* -- that is, guesses --
formed from observation, and the guesses are extrapolated to
implications which are then compared again against observation. There
is nothing *proven* to be true in physics. Nothing.
- You assume that time is infinite in extent. Again you do this by
induction, noting that every moment you can think of was preceded by
another observable moment. However, you haven't compared that
induction against the right set of observations. There is ample
evidence that time itself had a beginning at the big bang. It is
somewhat pointless to ask what there was before the big bang, because
"before" time exists is a meaningless concept.

Given finite existence, and the fact the time is only detectable given
change [and thus there couldn't be a [measurable] difference in time if
nothing [physically] existed], I would fully agree that the concept of
time [as we know/understand/experience it] is meaningless "before"
[outside of] physical existence.

- You assume that the laws of physics were in place during the big
bang and in fact governed why the big bang happened, and that
therefore the big bang should be explainable in terms of those laws.
We know for a fact that the laws of physics as we understand them
could not possibly have been in operation at the moment of the big
bang. It's therefore difficult to account for the cause of the big
bang in terms of physical laws foreign to us.

The laws of physics haphazardly mutating is an interesting point.
Something I'll have to think more on.


I.1 does not follow from any of the Fundamental Laws of
Thermodynamics.
The first law of thermodynamics doesn't have anything to do with the law
of conservation of [mass and] energy? How so?

There is no law of conservation of mass. There at one time was
believed to be one, and that is still included in the historical
sections of chemistry books, but it doesn't appear to hold up in fact.
Secondly, there is a law of conservation of energy, but it *only*
states that the total energy of a closed system doesn't change. There
is a common misconception about being able to conclude something about
the total energy of the universe on some absolute scale; there is no
absolute energy scale. For example, it is improper to say "When there
was nothing, the total energy of the universe must have been zero." To
understand the importance of the irrelevance of the zero point to the
energy scale, it is useful to spend a little time working energy-
conservation problems and changing the scale arbitrarily.

I'm not actually concerned about some absolute scale, just that it
really is closed. I'm completely unaware of this invalidation of the
conservation of mass and energy. If you could point me towards a good
read on such, that would be appreciated.

Careful. I didn't say conservation of energy was invalidated, only
that conservation of mass has been. Conservation of mass was useful as
a *chemical* approximation, but quickly dissolves when moving into
nuclear chemistry. I'm sure you've heard of binding energy and
conversion between mass and energy.

To learn something about the global implications of the arbitrariness
of the energy scale, find a popularization that talks about the Higgs
mechanism (flip through until you see a picture of potential energy
that looks like a sombrero) and cosmological inflation. If you read
that section through several times and repeat to yourself that the
zero point on that potential energy axis is *arbitrary* -- it changes
*nothing* about the physics -- then you'll start to see what I mean.


Now what say you?

argc Matie, ISO be all ANSI to set about the open C again...

Hopefully I didn't make [m]any errors [although I'm sure you can
probably help me with that ;) :P]. And now for something, completely
different [I was originally just going to say that it's sleeping time
[almost waking time?], but alas, it's up to tangential thinkers like
myself to keep focus straight ahead... just like nero].


.

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