Berkeley Lab Physicist Challenges Speed of Gravity Claim

spacedaily.com ^ | 23 Jun 03 | staff

[RadioAstronomer]

And Newton says that Gravity propagates at near instantaneous speeds.

Lets try a different tack.

If you have a flat sheet of rubber and you place a large ball on it, you will see a curve. If you roll a smaller ball near it the smaller ball will curve due to the bend in the sheet. This is a good analogy of a gravity field. This sheet is there all the time. However, a wave can be created in that sheet which will then propagate (but the original curve will still be there) along the sheet. If this is a gravitational field and a gravity wave, that wave will propagate at the speed of light according to General Relativity.

I am not sure I am saying this very well.

[RadioAstronomer]

What about chocolate and menopause?

Hmmmm... Not fond of chocolate and the wrong sex for menopause. Nope, not fundamental! LMAO! :-)

[Southack]

"It wouldn't matter, because even if the gravity that left the sun 8 1/2 minutes ago is what is effecting it, it would have the SAME effect no matter where the earth was in it's orbit"

Unless you think that Gravity can predict *where* the Sun and the Earth will be in the future, then Gravity must pull towards the center of the mass that originated it... where that center of mass was located when the Gravity wave first propagated away from that center of mass.

If the Sun didn't move, then this would yield us no useful information.

But the Sun does move, in fact it is moving rapidly (157 miles per second).

Light, for instance, takes 500 seconds to travel from the Sun to the Earth. In that 8.3 minutes, the Sun will have moved 78,186 miles. Thus, when you "see" the Sun, you are actually seeing where the Sun was located 8.3 minutes ago.

...And if Gravity travels as slow as Light, then the Earth is going to be orbiting in a plane that is centered around where the Sun was located 8.3 minutes ago, too.

And we *can* measure and observe the angle and center of the plane of the Earth's orbit around the Sun, FYI...

[Aric2000]

I seriously doubt it, you need something that is OUTSIDE the system, either moving towards us or away from us, in order to do such a measurement, because you need something outside the sytem to measure against.

[Aracelis]

So it is believed that all higher elements were formed in the vast energies of supernovae.

And thus, speculation is that our Sun is a third-generation star...because we have heavier elements.

[Southack]

You are stating the analogy just fine, but the limits of analogies come into play here because the sheet has no propagation speed and it has no movement of its own, either (nor does the big ball at rest in its center).

Your sheet even has bounds, something that we aren't trying (on this thread) to determine for Gravity.

What we want to know is how fast Gravity's influences propagate. If the Sun simply disappeared, would the Earth shoot off tangentally immediately, or would there be an 8.3 minute delay?

[Southack]

You doubt that we can measure the angle of the Earth's orbit around the Sun??

[Aric2000]

NO, because we can measure that, it is the gravity itelf that we cannot measure without an outside reference to measure against.

Within the system it is at equilibrium no differences, it remains the same,therefore you need something that is not in order to measure it.

[Aracelis]

wrong sex for menopause

Au contrair, mon ami...you gentlemen do indeed go through a similar "menopause". Mostly, it begins in your 40's, and often involves fast computers, younger women and radio telescopes. Telltale signs include (but are not limited to) spending long hours on message boards, stopping at every computer store within a 50 mile radius of home "just to look at what they've got", buying bigger dishes for that backyard radio telescope, jamming every possible new electronic gadget into an already crowded basement lab, and proselytizing others to join in a love of electronics and interferometry.

;^)

[RadioAstronomer]

the Sun simply disappeared, would the Earth shoot off tangentally immediately, or would there be an 8.3 minute delay?

It would take 8.3 minutes. Here is a good link:

http://itss.raytheon.com/cafe/qadir/q629.html

[Aric2000]

LOL!!!

Has she got your number or what?

[Southack]

If you can measure the angle of the plane of the Earth's orbit around the Sun, and if you know where the Sun and Earth are located and how fast they are traveling, what then would stop you from observing if the center of the Earth's orbital plane was focused upon where the Sun was located 8.3 minutes ago?

[Southack]

"It would take 8.3 minutes."

If so, then the orbit of the Earth's plane must be centered around where the Sun was located 8.3 minutes ago (78,186 miles from its present location).

Yet is that what we observe??

[Aracelis]

Hehe...I do indeed have his "number". :^)

[RadioAstronomer]

LMAO!!!!!!!!!!!!

[RadioAstronomer]

If so, then the orbit of the Earth's plane must be centered around where the Sun was located 8.3 minutes ago (78,186 miles from its present location). Yet is that what we observe??

The Earth/Sun SYSTEM is moving.

Its been fun, but I am way up past my bedtime. :-) See you tomorrow evening. Have a great night!

[Southack]

"The Earth/Sun SYSTEM is moving."

Indeed. Observing orbits would be pointless (in the scheme of determining the speed of Gravity) if our System was stationary instead of moving around at 157 miles per second.

[Aric2000]

Like I said, I am an amateur just using the knowledge that I have and a dose of common sense, I think that you are making it far more difficult then it has to be.

If Gravity travels at the speed of light, then the gravity that hits us now, left the sun 8.3 minutes ago. We are always in the same place relative to the sun, it takes us with it, therefore your question makes NO sense to me.

Because No matter what the NOW is, the earth is always on the same orbital plane, because the gravity that effects us NOW, is the same amount of gravity that will effect us 8.3 minutes from NOW. Now if the gravity had different strengths, then we could measure it, and we would bounce all over the place and be VERY uncomfortable.

It's been fun, but time for me to go to bed, have a very BIG 4 days ahead of me.

CQ Field day, CQ field day

Fort Flagler, Here I come!!!

[jwh_Denver]

"glued" to the wall with about 200 pounds of force."

Incredible. My brother had told me about what geckos can do but not how. Fascinating. So the geckos actually use "nuclear forces" to hang from a ceiling with one foot.

[jwh_Denver]

SORRY IF THIS IS GETTING COMPLEX

Fabulous simplification of a complex subject. You answered questions I didn't have before your post. I don't know how anybody could do explain it more simply. Great job!

If I may ask a question that has baffled me for years. My understanding is that the electrons circle the nucleus billions of times per second. That would create tremendous centrifugal force no matter how small the mass. Is it simply the the attraction of negative/positive forces or is there something else going on?