Re: Curved space

"Dick" <remdickhm@xxxxxxxxxxxxx> wrote in message
news:otk1e2hp1qc4enoe2mf8k8o193sljre714@xxxxxxxxxx
I am trying to imagine how space curves as a planet passes through. I
have seen the graph like grids curving away from the object/planet,
but nothing in 3D.

Is space rigid enough that it creates a "bow wave and wake?" If so how
far away from the local passage does the wave go? Does it extend into
space indefinitely setting up interference patterns as the curve
passes other curves?

Or, is space compressible like jello? Is the curve only local due to
space viscousness?

***


The universe is esstially two things, matter/energy and space-time.

Matter/energy is two forms. The cold, barionic, stuff we can see like
stars, planets, people... is only about 4% of the total matter. The other
96% is dark matter/energy that we can't see, but seems to be there based on
it's effects on the matter we can see.

Space-time appears to be litterally the "space" between different chunks of
matter. As this matter moves further apart, "space" is created.

Rather than think of space as "bent", imagine it as a "density". The effect
of matter/energy on space-time is to "increase" it's density in an r-squared
sort of way. Where there isn't significant matter, space is not very dense
or "spread out/stretched thin". Where you have a large object like a star
or planet, space gradualy get's more dense the closer you get. In a sense
it's "warped" inward toward the center of mass.

The result is an object passing by would appear to travel a curved path to
an observer. The appearance is that the original object "pulled" it out of
it's original trajectory. Where actually the object in motion's path was
altered as it incountered the "change in density"/"warpedness" of space
around the original objects.

The changes in the behavior of the different densities of space are what's
described by relativity. A yard stick in dense space would be shorter than
one in less dense space. A clock in dense space runs slower than in more
dense space. Of course if you yourself were to travel with a clock and a
yard stick from one point to another you wouldn't notice the difference
because you yourself, as in your physical dimensions in space and biological
clock are also subject to the changes along with everything else. So the
relativeness kicks in and you won't be able to tell the difference. You can
only measure from the standpoint of a neutral observer at a different
location.

If you're trying to imagine in 3D, picture spacial-density/"bentness" as a
color. Let blue represent normal space, so picture a empty cube filled with
blue representing a region of space. Now stick a planet in the middle. The
density of space at the survace of the planet is greater than the normal
blue space. Let red represent the higher density. Now just imagine a
transition through colors from red to blue, emminating from the surface out
and you have it. Not a perfect picture, but better than trying to convert a
bowling ball on a trampoline grid to 3D.

Now if you were paying attention, you may have picked up on something stated
from relativity that doesn't click with most folks. There is no such thing
as gravity. The "force of gravity" as we call it, is just the observed
illusion of one object "pulling" another. Where in fact the "pulling" as in
the thing that is affecting another object, is not really a force, but just
the behaviour of the objects as their motions are affected as a result of
the different density of space around them. The term "gravity well" lends
some clarity, but really it's a "spacial well".

You can even picture this as how gravity appears to work on the surface of
earth, keeping in mind that objects will move or be "pulled" from areas of
less dense space to areas of higher density. (Stuff flows downhill.)
Imagine yourself standing up and surround your body with an upright
rectangular box. Now to add in the effect of bent space just imagine the
square at the bottom of the box is smaller than the square over your head at
the top of the box. What you have is a box that's not all right-angles.
The space at your feet is more dense than the space at your head thanks to
the Earth. (It's the 3D equilivent to a bowling ball on a 2D trampoline
thing again.) Objects are "pulled" "down" not because of "gravity", but
because of matter's tendency to move in the direction of more dense space.

If you consider then what happens the more you bend space. Add more mass,
space bends more, keep going and you have a black hole. Black holes appear
then to be the storm drains of the universe. Matter (cold energy) bounces
around, interacts, forms stars, galaxies, etc... but ends up if it gets too
clumped together "vanishing" down a black hole. But now we know actually
that black holes aren't entirely black. They actually give off "Hawking
Radiation" in the form of elementry particles. They eventually evaporate
after having converted all the matter that fell into it. So rather than
storm drains, they're more like recycling centers.

As tricky as trying to imagine curved 4 dimensional space-time, if you look
into the latest varients of string theory that resulted when it and
super-gravity theories were combined, which now appears to be the most
promising attempt to merge the world of the big (relativity/gravity) to the
world of the small (quantum mechanics), it shows how the universe is
actually made up of 11 dimensions and not 4. Try to imagine that! Also the
latest thing is now "M-Theory", which is the first theory that seems to have
a chance at explaining what the big bang was.

Fun stuff.




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