This is a standard way to think of gravity:
represent a cross-
section in space
This dimension represents
the intensity of gravity.
In 1916 Einstein theorized that mass warps space, like a
heavy ball warps a sheet of rubber. That’s why this picture
is often used.
If the mass shifts, the warping follows, but can’t move faster
than “c” (the speed of light).
(There’s a heavy
A classic illustration (perfect for kids)
A ball rolling past a gravity “well” will be bent towards it.
I vividly remember seeing this demonstration,
at The Museum of Science and Industry, over
by the Coliseum. It’s the kind of thing that is
analytically sophisticated, yet visually sticks
in a kid’s brain.
I bet it’s still there.
The mass is moving
quickly, and the gravity
field is lagging a little.
Now the mass has stopped moving
This is the start of a
The mass isn’t moving anymore,
but its “gravity wave” continues
to radiate outward, like ripples
on a pond.
Just like a wave in water,
the farther the wave goes,
the weaker it is.
That’s why LIGO needs
very sensitive instruments
If an object were
oscillating back and forth,
waves would radiate
… but this doesn’t happen
easily (if at all)
But it is common for two
heavy objects to rotate
around each other
This will also create radiating
gravity waves, and that’s the kind
of thing LIGO is looking for.
Thoughts on LIGO:
The sequence of this package could be animated with
better-quality analysis software (giving smoother
The same method should allow modeling of the spiral
model I showed
It should look something like the waves left by two boats
as they spin around each other.
BTW, prediction of this phenomenon won a couple of
guys the Nobel Prize recently.
You should know this too:
According to Einstein, gravity is a warping of space, and the warping
of space is gravity. Gravity and space do not occur as two different
things (that’s what Newton thought) …the are basically the same
thing. Mass (what stuff is made out of) has “gravity”… more
properly, it warps space.
Oh, and… this space-warping is tied to mass, but not to light.
Scientists have been finding evidence for this warping effect over the
last 50 years. But there’s still a long way to go.
What LIGO measures is not “gravity” the way we’re used to thinking
about it. LIGO is a set of huge “yardsticks” that are constantly
calibrated by light. If/when a gravity wave passes, the yardstick
(made out of stuff) will be distorted, and the light beam (which is not
made out of stuff) can measure this distortion.
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