Re: Dragging on

On Apr 21, 6:40 pm, "Daniel G. Emilio" <dge...@xxxxxxxxx> wrote:
On Apr 19, 3:20 pm, carlip-nos...@xxxxxxxxxxxxxxxxxxx wrote:



Daniel G. Emilio <dge...@xxxxxxxxx> wrote:

On Apr 16, 10:08 pm, Sam Wormley <sworml...@xxxxxxxxx> wrote:
Dragging on
http://cosmicvariance.com/2007/04/15/dragging-on/
<snip> Although I have been missing
the action down south, there is one press release which was
conspicuous in its absence. A measurement of frame dragging was not
announced by theGravity Probe Bsatellite (affectionately known as
GP-B), as originally planned. Instead, NASA issued an Interim Report
summarizing the state of the data analysis thus far. <snip>
It seems to me there are two possibilities.
The first possibility is that frame dragging was detected but there
was a large error and they needed additional time to clean it up. (If
detected with only small error, they would never be funded for the
extension to December considering how much this experiment has already
cost. Further, if that was the case then wouldn't they also not have
announced the results of the geodetic effect). But if they detected
frame dragging at all, then why not announce that fact. There would
be nothing to lose.
The second possibility is that frame dragging was not detected in any
amount. If that was the case, then their silence regarding any result
is totally understandable. They would need, and would get, extra time
and funding to eliminate all possibility that extraneous factors
contributed to the null result and they would never make such an
announcement of null result until after they did everything they could
to confirm it.

The third possibility -- which is what is really happening -- is that
they won't know whether frame dragging was observed, and if so, how much,
until they understand their systematic errors better. In particular,
the experiment has four independent gyros, which are observed separately.
At the moment, the differences among the gyros is larger than the predicted
amount of frame-dragging. So, being good scientists, the GP-B people are
not yet prepared to make a claim one way or the other.

IIRC correctly each of those 4 gyro's was able
to measure the frame-dragging to 1%. Now it
sounds like the error bars are being pushed out
to 100%, (100x) because they didn't find it.

According to the people I've talked to, there is a good chance that the
differences among the gyros can be understood, in part because the mission
had a long calibration run to see how the gyros responded to various external
perturbations. If the external torques can be modeled, the results should
be good enough to give a fairly good number for frame-dragging. If they
can't, the conclusion will be that the experiment simply wasn't accurate
enough to say.

This sounds like the null result of the MMX,
if you can't find the ether, blame the equipment.
One way or the other, an equipment malfunction
occurred causing an error rate of 100x design
specification OR the frame-dragging effect is
100x less than theory predicted.
Since the geodetic effect banged in well, and no
previous report of 100x equipment design specification
error is indicated, the experiment proves there is
NO frame dragging.
It appears to be the case for LIGO too which is related.

Steve Carlip

On the other hand, I suspect that even if they do understand the
differences in the gyros and yet still do not detect frame dragging
the results won't be accepted in any event. Maybe I'm wrong. But
after 100 years I doubt if any negative result would ever make any
difference. There's simply too much invested to
scrap current thinking. If frame dragging is detected by any amount
then case closed. But if it isn't detected by any amount then case
still closed - there would never be a repeat of this experiment.

There may be other ways to do the experiment,
but I've seen calculations where it nulls out always,
IOW's it's a CS figment.
Ken S. Tucker

.

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