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  • geedee

Gravity has a speed !

[updated:LAST EDITED ON 09-01-03 AT 09:52 AM (GMT)]In my last one on whats the speed of dark, the topic of speed of gravity was brought up.

apparently gravity does have a speed…an astonishing speed actually…read on…:

Einstein was right. The speed of gravity matches the speed of light, according to astronomers who took advantage of a rare planetary alignment to measure one of the fundamental forces of nature.

Edward B. Fomalout of the National Radio Astronomy Observatory and Sergei Kopeikin of the University of Missouri measured the amount that light from a distant star was deflected by the gravity of Jupiter as the planet passed in front of the star.

Albert Einstein, who formulated basic theories about space, time and relativity, had assumed that gravity moved with the speed of light, about 186,000 miles per second, “but until now, no one had measured it,” said Kopeikin.

“Einstein was right, of course,” said Fomalout.

The measurement is one of the last fundamental constants in physics to be established and Fomalout admitted, “gravity is not well understood.”

The researchers used 10 radio telescopes scattered across the Earth from Hawaii to Germany to precisely measure how light from a distant quasar, a type of star, was bent as it passed by Jupiter on its way to the Earth. Jupiter is in the precise position for such a measurement only once a decade.

To make the measurement, the instruments had to detect a minute deflection of the light. Fomalout compared the required precision to being able to measure the size of a silver dollar sitting on the moon’s surface, or measuring the width of a human hair from 250 miles away.

Craig Hogan, a University of Washington astronomer, said the achievement “is an important advance for physics,” but he predicted that new techniques will be developed that will measure gravity’s speed even more accurately.

“You can expect a series of experiments now,” he said.

Fomalout and Kopeikin said their results are accurate within about 20 percent.

Knowing the precise speed of gravity is important to physicists testing such modern ideas as the superstring, which holds that fundamental particles in the universe are made up of small vibrating loops or strings. It also affects some basic space-time theories.

So there you go !

This then raises the following question’s.

1. If a pencil was dropped in a 100%, totally blacked out room, from any height, would it drop at the speed of light ? (would you be able to see that it had dropped ?)

2.Would it drop cos if theres no light, it cant fall at that speed so it should hover !

3.If it did drop at the speed of light, would it create light, thus proving that it was in fact falling at that speed

4. Would it create multiple sonic booms while dropping or would it make one big bang ?

5.Would it burn up do to friction or explode as a result of the pressure wave at the speed of light

I’m just interested you understand ?

Cheers

Gary

And NO, I’ve not been at the C*rlsb*rg yet either !!!

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By: Arabella-Cox - 10th January 2003 at 00:52

RE: Gravity has a speed !

A potentially interesting discussion…

…until the silly questions. 🙁

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By: geedee - 9th January 2003 at 19:00

RE: Gravity has a speed !

LOL

Nice one Dave

BTW welcome to the Forum

cheers

Gary

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By: Arabella-Cox - 9th January 2003 at 18:58

RE: Gravity has a speed !

wait…don’t get mixed up with gravitational propagation velocity and gravitational force. The pencil question is all about gravitational force inside a local gravitational reference frame, beside the mass at speed of light issue.

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By: Bluetooth - 9th January 2003 at 18:20

RE: Gravity has a speed !

A black hole sucks in light so gravity is obviously faster.Does this also mean that gravity can move energy?

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By: Glyndwr - 9th January 2003 at 14:05

RE: Gravity has a speed !

Seeing as gravity is also dependant on mass, and once the pencil gets close to the speed of light, it reaches infinate mass, would the eraser on the end turn into a black hole? In which case, once the pencil reaches the event horizon, it would appear static to the observer, as time outside the event horizon appears to stand still, but not for the pencil! As the pencil is in a totaly blackened room this can’t be observed and as our uncle Albert once said. “Time is only relevant to the observer” would the experiment be void? Or would the pencil, along with the little rubber bit at the end turn into a singularity?
You just know this stuff will keep you awake all night!

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By: munnst - 9th January 2003 at 13:45

RE: Gravity has a speed !

Gravity is a constant.
Gravy however is a random unconstant.

The speed at which Gravy falls is governed by many factors. The cheapness of the Gravy boat, the size of the ladel, the clenliness of the table cloth, the expense of the shirt and the criticality of the relatives you have asked around for dinner.

This can be expressed as;

gravy=tablecloth/ladle*relative(^shirt)

Of course Gravity comes into play with the speed of the drip.
This is known as the Gravy Gravity Drip Criticality factor.

HTH.

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By: Hand87_5 - 9th January 2003 at 12:22

RE: Gravity has a speed !

Some people were sceptical when I brought this up , but I wasn’t kidding.

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By: KabirT - 9th January 2003 at 11:59

RE: Gravity has a speed !

yea this was in the papers here too.

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