Wednesday, July 22, 2009

On Cosmology

A philosophical dialogue, discussing the nature of the cosmos. In the mold of Galileo.

Simplicio: So what if the stars one day was gone,
and what if the wind died to ask away.

Salviati: That sounds kinda neat.

Simplicio: not realty

Salviati: Why is it not neat?

Simplicio: becues
it would be
all the time

Salviati: But if the stars were gone, it'd get rather cold, wouldn't it?

Simplicio: no

Salviati: Well, no heat.
(The Sun is a star.)
So the Earth would begin to cool.
Radiating its finite supply of heat into uncaring space.

Simplicio: what
since when

Salviati: Since Copernicus?
Well, no. [This was an error. Kepler would have been a better choice.]

Simplicio: i dont believe

Salviati: Quick!
In which year did the Papacy admit that the Earth was not stationary?

Simplicio: what

Salviati: 1992!

Simplicio: it isnt

Salviati: Not really, no.

Simplicio: since when

Salviati: Since its formation?
(From the protoplanetary disc.)

Simplicio: ...
where is it going

Salviati: In an ellipse!

Simplicio: how do you know

Salviati: The variations in speed and direction of the apparent motion of the Moon, Sun, and planets!

Simplicio: what if they are moving
around the earth
did you ever thing of that

Salviati: Yep!

Simplicio: ?

Salviati: See, if they are, then things get really messy.
You have to add all kinds of arbitrary fiddliness to the orbital mechanics to accomodate them.

Simplicio: ok
do that

Salviati: Why, when the maths are so much cleaner for a heliocentric system?
It just makes more sense!

Simplicio: that just
you know
maht man
you know
cant prove

do you think
the earth
is round

Salviati: Hmmmmmmmm
Well, yes.

Simplicio: what
that doesnt
any sense

Salviati: Sure it does.
How else do you explain time zones?

Simplicio: like
one part
is closer
to the sonne
the other

Salviati: How would that cause one part to be dark, while the other remains light?

Simplicio: man
if you stond
in a dark
and then
you turn on
the light
the part
that was far
is still dark

Salviati: ..."The part that was far"?

Simplicio: from
the light

Salviati: Not really.
Not unless you're standing in the way.

Simplicio: its more dark
the close

Salviati: True; but the light is still clearly visible.
This is not so, at night.

Simplicio: it is

Salviati: You can see the sun at night?

Simplicio: the moon

Salviati: So your argument is that the moon and the sun are one and the same?

Simplicio: ya

Salviati: Then how do you explain those occasions on which you can see both at once?

Simplicio: its just
you know

Salviati: No, I don't.
Do explain.

Simplicio: ilke
if you lond you finger
to your nose
its like
you can see
a hot dog

Salviati: No you can't.
What are you talking about?
Are you hallucinating?
Have you had too much of the hashish?

Simplicio: ..

Salviati: Probably exploting the blind spot of the eye, I guess?
I can't really do it.

Simplicio: well
that is how
that works
if the world
is round
how can you live
on the bottom
you fall off
you know

Salviati: Look to the ancients, my friend.
Aristotle wrote that each object seeks its own proper place.
Rocks seek the ground; balloons seek the sky.
Thus, a person on the "bottom" of the earth would seek the ground just as we do on the "top", and percieve matters in the exact reverse way.
Does that settle your concern?

Simplicio: but then
if they camt
to the top
then they fall off

Salviati: Not so.
A person is not bound to where they are born; just as if you take a rock up from the ground, and carry it a hundred miles, it will not seek to roll back to its origin!
The ground is the ground wherever it should be, on the 'top' of the earth, the 'bottom', or anywhere in-between.
We seek but the nearest point.

Simplicio: man
you are crazy

Salviati: Pah!
Ad hominem!
And unsubstantiated, at that.
If I am crazy, what proof do you have for it?
We deal in logic here, my friend, not mud-slinging!

Simplicio: are you saying
there is like
some force
that draws
to the earth

Salviati: That could be the mechanism.
I offer no opinon on the matter.

Simplicio: then
why the sun
doesnt crash

Salviati: Well, we know that this hypothetical "force" obviously doesn't operate on all objects.
Recall, balloons seek the sky, not the earth.
Perhaps the Sun seeks its own position, instead.

Simplicio: but
if you put the air
out of it
it goes down

Salviati: True.
(Also, it'd have to have helium or hydrogen or such inside - a balloon filled simply with air, unless heated, will just be quite light... but I digress.)
I'm not sure what your argument is.
That if you take part of a balloon out, it ceases to be a balloon?

Simplicio: no
its still
a balon
it doesnt go up

Salviati: A problem with terminology, I suppose.
Call it a "filled balloon".

Simplicio: en
when you go to
the moone
you are not

Salviati: Ahhhhhhhhhhhhh.
A wise question!
Perhaps the attraction we feel towards the earth diminishes with distance; just as a wealthy merchant's loyalty to his wife varies as he travels.

Simplicio: .........

Salviati: Or perhaps we might feel such an attraction to any great body; the Earth, the Moon, even the Sun, could we somehow travel there.
Or both!

[A pause, as the participants in the dialogue break for croissants. On their return:]

Simplicio: how can the earth go around the sun
then it would have to move
and it have
no legs
or wings
you would feel
the wind
going fast
around it

Salviati: Give me a moment.
Firstly: Many things move without legs or wings.
Consider a hurled stone.
Has it legs? Has it wings?
Not unless you're abusing a piece of statuary.
(In which case you are to be chastised.)

Simplicio: but

Salviati: Nonetheless: it moves!

Simplicio: there is nothing
to hurl
the earth

Salviati: Let us consider a model, for a moment.
It will start seemingly unrelated; but hear me out!
It will come around to the matter in good time.
Let us consider a young solar system.
The Sun already burns; but no planets are in evidence.

Simplicio: that

Salviati: Instead, there is a wide, thin disk of matter, occasionally appearing to clump.

Simplicio: becuse

Salviati: Waiting.

Simplicio: becuse
created the earth
there was light

Salviati: Incorrect!
First God said, "Let there be light".

Simplicio: no

Salviati: Then he created the heavens and the earth.

Simplicio: In the beginning God created the heaven and the earth.
And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
¶ And God said, Let there be light: 2 Cor. 4.6 and there was light.

Salviati: Da[ng], I'm rusty on my scripture.
All right, two possible arguments here.
The first: Scripture does not accurately represent events.
I will keep this in reserve.
(Heh, amused at your copy-paste's linking.)

Simplicio: ?

Salviati: All right.
Note that God created the heavens and the earth - in that order!
That implies that the Sun, which is in the heavens, was created before the Earth.
So why was there no light?
The Earth was shrouded in dust and ash from the processes that formed it.
When they were done - voila - there was light!

Simplicio: huh

Salviati: May I continue with my model?

Simplicio: ok

Salviati: So, the Sun is surrounded by a thin disk of matter.
Ah - for this model, we must assume that matter attracts matter, like to like, in proportion to its mass and inverse proportion to the distance between the masses.
My apologies for the added proviso.
With this, though, we may see that clumps of matter will grow and grow; small lumps attracting others nearby and turning into larger lumps, and then larger lumps.
Eventually, nearly all of the original debris will be sucked into one lump or another.
Most of the lumps will have little momentum to begin with; they will be inevitably attracted to the Sun, and vanish therein.

Simplicio: but
why doesnt small things
clump together

Salviati: Because they are far too small for the effect to be noticed!
Let us say that I decide to push the side of a five-deck galleon with my finger.
There is a force exerted - but can you notice it?
Not so!
It would be the same here.
Oh, alternately - I'm going to continue with the model in a moment, but I just thought of a much better explanation for why the Earth doesn't fall into the Sun.
Who says the Sun is made of matter?

Simplicio: becuse

Salviati: Wait, no, that wasn't your original question.
Ah well.

Simplicio: it is hot

Salviati: Moving on.
On the subject of our increasingly-large lumps:
But a few of them will have some siginificant momentum perpendicular to the line connecting them and the sun; then when the Sun attracts them, their path describes a circle.
(For all that is needed to create a circular path is a force pointing to the centre of the circle, with magntitude equal to the current momentum of the object travelling the path.)
(Not sure about that, actually.)
(Let me think for a second.)

Simplicio: ...

Salviati: (...yeah, basically.)
So only a few of the lumps would 'survive', but those few would all spin around the Sun.
This accurately describes what we see.
So the model, barring further objections, appears valid.
(This is the anthropic principle, basically.)
Are you satisfied with this answer?

He was.


No comments: