More Science Stuff

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More Science Stuff

Postby Don_U » 05/05/11, 9:51 pm

I never look back, dahling, it distracts from the now -Edna Mode
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Postby bob » 05/06/11, 1:14 am

saw that. interesting.

Here's a fun mindbender -- visualize a sphere's gravity, sucking in space around it. And the mindbending part is the gravity asserts itself in every direction. (I.E., spherically (is there a word for that? 360 degree angle is not correct, since it would be 360 degree squared, n'est pas?))

Add a layer, and, as the recent experiment shows, a spinning sphere would spin the space around it, frame dragging, as they say. And don't forget that gravity's effect is never entirely depleted by distance, so that, albeit slowly, the entire universe is spinning around every spinning sphere/mass. Well, maybe... There are a lot of intervening forces too. (Partially quoted from an article -> "The farther apart two objects are, the lower the gravitational force between them, so gravity gets weaker with distance. To be specific, it decreases by the square of the distance. So if you double the distance, the force of gravity is 1/4 as strong. If you triple the distance, the force is 1/9 as strong, and so on." But no matter how fractional, the effect is never entirely depleted.)

I like to think about these things....

I've always hated the inaccuracy of the model of gravity as a heavy ball sitting in a depression on a mattress. it leaves so much out of the "equation." Gravity springs from all sides of any mass. To picture it on the mattress implies a unidirectional gravity. I.E. it's just on the bottom.

The crux of the article:

"Einstein’s theory relates gravity to the sagging of cosmic geometry under the influence of matter and energy, the way a sleeper makes a mattress sag. One consequence is that a massive spinning object like Earth should spin up the empty space around it, the way twirling the straw in a Frappuccino sets the drink and the whole Venti-size cup spinning around with it, an effect called frame dragging. Astronomers think this effect, although minuscule for Earth, could play a role in the black hole dynamos that power quasars.

"Empty space in the vicinity of Earth is indeed turning, Dr. Everitt reported at the news conference and in a paper prepared for the journal Physical Review Letters, at the leisurely rate of 37 one-thousandths of a second of arc — the equivalent of a human hair seen from 10 miles away — every year. With an uncertainty of 19 percent, that measurement was in agreement with Einstein’s predictions of 39 milliarcseconds.

"Likewise, the “sag” should alter the space-time geometry around Earth, warping it from the Euclidean ideal and cutting an inch out of the Gravity Probe’s orbit around it, so that the circumference is slightly less than the Euclidean ideal of pi times the orbit’s diameter, a fact confirmed by the Stanford gyroscopes to an accuracy of 0.3 percent."
Last edited by bob on 05/09/11, 2:45 pm, edited 1 time in total.
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Postby Don_U » 05/06/11, 3:24 pm

I think the pillow thing is easy for folks to understand.

heh heh try explaining that the only reality here is that our world, their lives, are built on events in time and that is it. Oh, and that there are complex distortions in time that effect that outcome.
I never look back, dahling, it distracts from the now -Edna Mode
Beware of men in white vans at the freeway off ramps selling discount America. It is defective,
contains lead, and is not made here.
Robotic Undertones
Don_U
Senior Member I Get Free Beer
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Posts: 766
Joined: 08/03/09, 10:33 am
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